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Is there any way, shape, or form that ultraviolet light is recorded by a digital sensor? Ideally, this question is related strictly to the sensor, without even a glass lens in between which could cut or block UV light. But of course I don't take pictures with a bare sensor, I also have a lens, so I'd also like to know how much UV gets to the sensor to begin with.
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3 Answers 3
up vote 22 down vote accepted
Yes, digital sensors are indeed sensitive to UV light, as well as a considerable amount of the infrared spectrum. Most digital sensors are equipped with multi-coated, multi-layered filters that are designed to filter out the extended ranges of UV and IR. Generally speaking, filtered digital sensors are sensitive to a much broader range of light than the human eye, from about 250nm (the near-UV range) through visible light (400nm to 750nm), and down about 780nm (the IR range). Unfiltered, a digital sensor is sensitive to a far greater range, from deep UV (200nm, true UV) down to true IR (as far as 900nm) [#1]. It should be noted that sensitivity is not constant throughout this range, and falloff is fairly rapid and becomes significant the farther away from 380nm you go. Same goes for the IR range. Human eyesight ranges on average from about 390nm through 700nm, while some people are more sensitive and able to see from about 380nm through 750nm.
Despite the filtration applied to digital sensors, UV light is still a problem, and can affect color balance. In general, the ability to sense UV light is not a huge problem, as digital sensors have relatively weak sensitivity to blue, and the UV sensitivity is generally captured as blue. However, without proper filtration, UV dispersion can generate disruptive haze that can be captured by a digital sensor, which may result in a rather undesirable result.
It should be noted that optical glass filters out a considerable amount of UV light. Most UV wavelengths up to around 310nm are blocked by the glass of a camera lens, and the remainder from 310nm up through 380nm can be blocked with a UV/Haze filter. If one wishes to create images in the UV light range, special lenses are available. Non-standard materials such as quartz or calcium fluoride have a greater transparency to the UV spectrum. From a camera imaging perspective, most research shows the most interesting UV wavelengths probably lie between 250nm and 310nm [#2]. To get a clear UV shot, you may need to remove the UV filter that covers the sensor itself. This is similar to removing the IR filter when modifying a camera for IR work, or may involve removing the entire filter apparatus, which would remove both UV and IR filters at the same time (depends on the camera.)
 1. Infrared and ultraviolet imaging with a CMOS sensor having layered photodioedes
 - Introduction discusses unfiltered layered CMOS sensitivity range: 200nm - 1100nm
 - Layered CMOS (i.e. Foveon) tend to have a greater sensitivity range than bayer CMOS
 - Interesting discussion about the individual wavelength sensitivity of each color photosite (graphs included)
 - Seems a little out of date (2003/2004 period?), but still useful
 2. Digital Reflected-Ultraviolet Imaging
 - Older article from several years ago, covers reflected-UV imaging
 - Discussed the nature of UV imaging and how it differs from visual/IR imaging
 3. The Wratten 18A: A problematic filter for reflected-UV photography
 - Interesting article that uses an original Canon Rebel and a Wratten 18A filter to image UV
 - The Wratten 18A allows UV from ~290nm through 400nm
 - The older Canon Rebel CMOS sensor seems to image this wavelength range well
 4. Visible Light CMOS Sensors
 - Page 7 has a graph of CMOS vs. Human Eye sensitivity
 - Stops at 400nm, but shows that the CMOS sensitivity curve is still quite high at that point, and falls off at a moderate curvature (likely ends around 250nm-290nm)
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Wow, lots of good information here. Do you have any sources to cite? – jfklein13 Aug 9 '10 at 21:11
I do, however they are bookmarked at home. Also, sadly, most of them were PDF scientific papers. The best one had to do with scientific imaging in UV, and discussed alternative lens element materials like quartz and fluoride derivatives. I'll see if I can dig them up. – jrista Aug 9 '10 at 21:25
I am not sure I actually bookmarked any of the stuff I've read about IR and UV imaging with digital cameras. There is a moderate amount of information available on the subject, but I remember most of it being contained within PDF's, usually some scientific paper or official study of some kind. I will have to redo my searches to get you citeable references. – jrista Aug 10 '10 at 17:34
The widely accepted view is that they are not. However, see this description of empirical tests (from 2004) which seems to establish that the digital sensors tested were UV sensitive, albeit much less so than is film.
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This "accepted" view is generally only because most of the published specifications only provide sensor light absorption and sensitivity information from about 400nm through 750nm, the visible light range. Most of this information indicates that the blue photosites on a sensor peak at around 380-400nm, but do not show where they begin. Independent third-party studies show that the UV sensitivity of digital CCD and CMOS sensors starts much higher, from 250nm down to as low as 200nm. – jrista Aug 9 '10 at 18:30
Yes, they are as pointed out. But I want to add that sensors in digital cameras are not actually digital.
The Image sensor converts light into an electronic signal. Just because it's electronic, doesn't mean it has to be digital. There are analog signals and digital signals. both of which are electronic.
After this it goes through an analog-to-digital converter. Well, it actually goes through an amplifier before this but anyhow. This is where it then becomes digital and can be processed, compressed and all what ever else it's been programmed to do.
Just thought I'd put that out there.
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protected by John Cavan Apr 24 '13 at 17:30
Would you like to answer one of these unanswered questions instead?


text:
Use the following tips and techniques when you design a UML 2.0 Activity Diagram. Usually you create Activity Diagrams after State Machine Diagrams.
To design a UML 2.0 Activity Diagram, follow this general procedure:
- Create one or more activities. You can place several activities on a single diagram, or create a separate diagram for each.
Warning: You cannot create nested activities.
- Usually activities are linked to states or transitions on State Machine Diagrams. Switch to your State Machine Diagrams and associate the activities you just created with states and transitions.
Tip: After that you can find that some more activities must be created, or the same activity can be used in several places.
- Switch back to the Activity Diagram. Think about flows in your activities. You can have an object flow (for transferring data), a control flow, both or even several flows in each activity.
- Create starting and finishing points for every flow. Each flow can have the following starting points:
- Initial node
- Activity parameter (for object flow)
- Accept event action
- Accept time event action Each flow finishes with a Activity Final or Flow Final node. If your activity has several starting points, they can be used simultaneously.
- Create object nodes. You do not link object nodes to classes on your Class Diagrams. However, you can use hyperlinks for better understanding of your diagrams.
- Create action nodes for your flows. Flows can share actions.
Warning: You cannot create nested actions.
- For object flows, add pins to actions. Connect actions and pins by flow links.
- Add preand postconditions. You can create plain text or OCL conditions.
- You can optionally create shortcuts to related elements of other diagrams.
To add an activity parameter to an activity:
- In the Tool Palette, press the Activity Parameter button.
- Click the target activity. Or: Choose AddActivity Parameter on the activity context menu.
Result: An Activity Parameter
node is added to the activity as a rectangle. Note that the activity parameter node is attached to its activity. You can only move the node along the activity borders.
Note: Activity parameters cannot be connected by control flow links.

source: HuggingFaceFW/fineweb-edu


text:
Weed Seed: Linaria genistifolia (Broomleaf toadflax)
Canadian: Absent from Canada (Brouillet et al. 2016Footnote 1).
Worldwide: Native to central and eastern Europe and temperate Asia (USDA-ARS 2016Footnote 2). Introduced in France, Germany, Norway, and the United States, where it is present in Oregon, Minnesota, and some of the northeastern states (CABI 2016Footnote 3).
Duration of life cycle
Seed or fruit type
- Seed length: 0.6 - 0.8 mm
- Seed width: 0.4 - 0.5 mm
- Seed blocky, often with one tapered end
- Seed covered in ridges that form a wavy-wrinkled pattern
- Seed black with a bluish or silver sheen, immature seeds are greyish
- The seed edges are reticulated and winged, approximately 0.2 mm wide
Habitat and Crop Association
Pastures, roads and disturbed areas (Darbyshire 2003Footnote 4).
Dalmatian toadflax (Linaria dalmatica)
- Dalmatian toadflax seeds are a similar size, blackish colour, rough surface and sharp winged edges as broomleaf toadflax.
- The shape tends to be more blocky without one tapered end and the winged edges do not have a strong microscopic pattern compared to broomleaf toadflax.
Striped toadflax (Linaria repens)
- Striped toadflax seeds are a similar size, dark colour and rough surface as broomleaf toadflax.
- Striped toadflax seeds lack a winged edge and have a dull brownish surface compared to broomleaf toadflax.
- Date modified:

source: openbmb/Ultra-FineWeb


text:
What is The 90/90 Hip Lift?
The 90/90 Hip Lift is an integral and foundational exercise from the Postural Restoration Institute (PRI). It is often taught in the foundational courses from PRI, and it is often where many clients, patients, and athletes begin their PRI journey. As a practitioner, I find myself coming back to this piece quite often, as it allows me to see an individual's motor control in many specific areas and more.
The 90/90 Hip Lift is an exercise that begins in a supine position (on your back), with your feet on an elevated surface, and knees in a flexed (or bent) position.
Sometimes you can have something in between your knees, other times not. The following article will describe more beyond just the initial position. The execution of this movement may be the most underrated aspect of this exercise, as a well executed 90/90 Hip Lift can help teach foundational lessons for further exploration later on.
Background for Using This Exercise
There are lots of reasons why someone might want to use this exercise. Reasons may involve relieving a certain region of sensory pain, improving sensory awareness of the body, and perhaps improving injuries that are often re-occurring. More specifically, the science of postural asymmetry and its effect on the body is evidenced from the Postural Restoration Institute's multi-disciplinary approach.
At the end of the day, there are several internal and structural asymmetries that are present in the human body, along with hemispheric (or brain) asymmetries that can dictate varying function of the body. For example, there is a liver on the right side of the body, and the heart on the upper left side of the chest wall. Further, there are different attachments of the diaphragm, with the right crus of the diaphragm being stronger, broader and longer than the left diaphragm.
In the brain, there are different structures that are more neurologically active in the right vs left hemispheres. For example, Broca's and Wernicke's area are found in the left hemisphere for language production, but not in the right hemisphere. This has a great impact on asymmetry for communication and interpretation of language. (1)
With this said, the purpose of varying movements isn't necessarily to "eliminate" any asymmetries as a cause of this and be as perfectly symmetrical as possible, because this would need for you to move your heart, liver, re-arrange your physical brain, along with removing other key body parts, but rather understand and acknowledge the body's asymmetry with respect to performance on a daily or competitive level.
From a clinical perspective, I find myself utilizing the 90/90 Hip Lift from a foundational perspective, as it is often the first position that is introduced from a motor control position:
- It's easier to learn finer detailed movements, and adapt them from this position
- You can change multiple positions of limbs, such as legs in adduction/internal rotation or the opposite leg in abduction/external rotation, while still being in the base 90/90 Hip Lift position
- It's perhaps easier to feel and sense muscles activating
- It allows you to focus on breathing as well
Often I may progress from this 90/90 Hip Lift position to sidelying, seated, or even progressing to standing if it is necessary to do so.
Populations that May Benefit:
- Individuals who are placed into chronic positions (due to work, constant standing, etc.)
- Anyone looking to improve upon their body's musculature, particularly the hamstrings, abdominals, and gluteals
- Populations that find themselves "neurologically stuck" in an extended posture bilaterally
- Individuals who experience further symptoms secondary (or because of) a tight lower back, anterior hip pinching during squatting, or even hip discomfort during lunging, among other things
- Individuals who display excessive hip or femoral external rotation (barring osteoor bony adaptations), and are looking to improve hip internal rotation values
Instructions for the 90/90 Hip Lift
From the PRI manual verbatim
- Lie on your back with your feet flat on a wall and your knees and hips bent at a 90- degree angle.
- Place a 4-6 inch ball between your knees.
- Inhale through your nose and exhale through your mouth, performing a pelvic tilt so that your tailbone is raised slightly off the mat.
- Keep your back flat on the mat. Do not press your feet into the wall, instead dig down with your heels. You should feel the muscles on the back of your thighs engage.
- Hold this position while you take 4-5 deep breaths, in through your nose and out through your mouth.
- Relax and repeat 4 more times.
Understanding and Executing the 90/90 Hip Lift
It is my hope that if anything, you stick to the "algorithm" if you aren't comfortable moving beyond this level. However, this is my site, and I'd like to provide you with my interpretation of how to improve your execution of the 90/90 Hip Lift.
With Table A, there are 8 pieces that essentially need to take place before moving on. If they don't take place, can you really say you've achieved authentic muscular contractions in the correct manner?
- Can you say you've achieved a posterior pelvic tilt, if indeed you haven't achieved a posterior pelvic tilt without the hamstrings and obliques?
- Can you say you've achieved compression of the anterior superior and inferior ribcage if you haven't inhibited the pectoralis major/minor, and utilized the obliques and serratus anterior attachment on the ribcage?
- Can you say you've achieved an appropriate zone of apposition if you use accessory neck musculature to help with breathing, instead of the abdominals, thoracic diaphragm, and pelvic diaphragm?
Now, with the process of troubleshooting, it is definitely okay to miss key elements, because that is the point – you haven't learned the whole movement, so you'll be acquiring one piece at a time. It may in fact take 5-10 minutes (or even days, weeks, or months!) to teach the sensation of what posterior pelvic tilt means without using any musculature that does not contribute, for example.
One key item to not overlook is the bolded red mechanical action of ribcage compression on inhalation – the reason being that you don't want your ribcage to flare and expand upon inhalation, when you just achieved your position. This effectively loses the mechanical advantage that your internal obliques have on your ribcage and pelvis, along with utilizing the diaphragm to help improve upon thoracolumbar and ribcage positioning … which is the whole point of the exercise.
At the end of the day, learning the 90/90 Hip Lift will set the stage for greater stacking as we progress towards the 90/90 Hip Shift, and 90/90 Hip Shift with Integration.
So, if you only have 12.5% of Table A, that is fine, as long as you progress towards 25% the next time you practice it, then onwards to 37.5% while also retaining the original first piece to this puzzle in the process.
Cueing and Attention
A common denominator among many of these PRI activities is the attention to detail found in the movement itself, along with the execution of these exercises from the athlete's perspective.
When you have an activity that requires attention in more than one area, such as acquiring and maintaining sensation in hamstrings (back of your legs) and adductors (medial aspect of your legs) simultaneously, it quickly becomes apparent that some level of interoception, or a lesser-known sense that helps you understand and feel what's going on inside your body, is necessary. However, as a coach, how do you prioritize which piece of the movement to coach? How do you allow for ease of understanding? Is interoception detrimental towards performance (similar to internal attentional focus)?
Something familiar for coaches to recognize and coach is a back squat. At the end of the day, it is simple. It involves a level change (standing tall to sitting down) with a fixed torso (that does not fold nor bends during the movement), and there happens to be a barbell on your back. Initially it is as easy as that, but then eventually you'll need to pay attention to:
- Hand position
- High bar vs low bar
- Foot width and position
- Intra-abdominal pressure
- Visual gaze
… among many other nuances found in a wide variety of successful squatting.
However, despite all of these individual pieces that can be fine tuned in the back squat, how can any individual successfully back squat when there can be anywhere from 5 to 8 items to pay attention to in the squat?
This answer lies in the sensory processing and motor output associated with different movements and is analogously related to how the 90/90 Hip Lift can progress and advance beyond its simplistic nature.
Understanding Sensation and Sensory Processing
"… The nervous system extracts only certain pieces of information from each stimulus while ignoring others… Thus, we receive electromagnetic waves of different frequencies, but we see them as colors… Colors, tones, smells, and tastes are mental creations constructed by the brain out of sensory experience. They do not exist as such outside of the brain."(Kandel et al.) (3)
Writing a whole bit on perception in less than a paragraph would be a disservice since there are literally books upon books on the topic, so I'll save that document for another 3000+


text:
Spectroscopy and Unknowns
Sarah Madden, Matt Grandbois, Eric Nelson
October 31 and November 7 2000
Chem 120 H / Viste
The purpose of this lab was to identify an unknown using various methods of spectroscopy. The unknown could have contained any or all of these elements: carbon, oxygen, and chlorine. The number of carbon atoms in the unknown molecule ranged from one to six. The following methods of spectroscopy are various ways to obtain the spectrum of an unknown: FTIR (infrared), which relates to molecular vibrations; Raman, which relates to molecular vibrations; NMR (nuclear magnetic resonance); GC/MS (mass spectroscopy); and UV-vis (ultraviolet-visible). Other chemical characteristics that can help identify organic unknowns are the boiling point, refractive index, and the flame test.
The lab began with obtaining an unknown organic compound. The first test that was completed was the Beilsteinís flame test for the presence of chlorine. The next part of the labs involved observing different types of spectra through use of FTIR, Raman, NMR, GC/MS, and UV-vis. The refractive index and the boiling point of the unknown were also found. The results of these various tests along with the different spectra types were then analyzed and the unknown was identified.
Beilsteinís Test: no chlorine
Boiling Point: 139-141 o C
Refractive Index: 1.4504
Additional Raman Spectra
NMR (nuclear magnetic resonance):
GC/MS (mass spectroscopy):
Cyclohexanone vibration 27:
Vibration Spectrum 35:
Microscopic picture of the atoms.
In this lab various methods of spectroscopy were used to identify an unknown. Based on observations and analysis of the spectras the unknown of this lab was identified as Cyclohexanone.


text:
Blank rows aren't bad, but in most sheets, they're definitely undesirable. Excel uses blanks to determine data ranges, and a blank row in the wrong place will inhibit many built-in features. Fortunately, there's an easy way to remove blank rows from a data range, but this easy technique has the potential to destroy data, so you must be careful.
The first step is to select the data range. Using the simple sheet below (Figure A), you'd select A3:E14. As you can see, there are two blank rows (7 and 10). Admittedly, in a sheet this simple, you'd probably just delete the rows manually. That won't be as simple in a large data range that comprises thousands of rows!
After selecting the data range, continue as follows:
- Press [F5].
- In the resulting Go To dialog box, click Special.
- Click the Blanks option and click OK. Doing so selects the blank cells (what you might think of as rows) in the selected range. In this case, that's A7:E7 and A10:E10.
- Now you're ready to delete the selected cells. On the Home tab, click the Delete dropdown in the Cells group and choose Delete Cells. Excel will display the Delete dialog box, with the Delete Cells Up option selected. Click OK. Or, press [Ctrl]+-. Excel will delete the blank cells from the selected data range.
Choosing Delete Cells deletes only the blank cells in the previously selected range. If you choose Delete Sheet Rows in step 4, you could potentially destroy data (often unseen) to the right. Choose carefully when using this option to delete blank rows when you really want to delete just the blank cells. It's easy to think in terms of rows and choose the wrong option!


text:
Can chickens provide early warnings of wind turbine health dangers?
By Miriam Raftery
August 21, 2011 (San Diego's East County) – Like those proverbial canaries in the coal mine, chickens near wind farms may provide early clues to potential harm to health of humans and animals. That's the contention of Hamish Cumming, a farmer battling proposed wind turbines near his home in Australia.
He has written a letter to East County Magazine seeking help from people living near wind farms locally (and in other locations) to document cases of shell-less eggs, dead chickens, or other animals that suffer internal hemmorrhaging.
The "humble chicken" is common in rural areas near wind farms and can be easily monitored, Cumming says. Chickens under stress may produce a soft-shelled or shell-less egg that can't be laid, killing the chicken. Such incidents have been documented near wind farms, says Cumming, who has also collected examples of livestock and a dog that died from internal hemorrhaging near wind farms.
"There are reports from many wind farm locations that chickens within a 3 km distance from turbines exhibit shell-less eggs during some weather conditions," he stated. "Some locations have reported shell-less eggs or dead chickens that coincide with residents' complaints about "noisy nights" from turbines."
In fact, shell-less eggs are also known as "wind eggs." According to Broad Leys Publishing, which specializes in books for poultry owners, a yolk-less wind egg may occur in a young pullet, but "wind eggs can also occur in older hens if they are subject to sudden shock."
Chickens aren't the only species suffering ill health effects from living near wind farms, Hamish says.
"So far there are several records of dairy cattle in Canada and Australia reducing milk output by as much as 30%," he wrote.
The Discovery Channel ran a report on massive deaths among bats that suffered lung hemorrhaging when flying near wind turbines: _URL_
Goats in Taiwan, verified by the Taiwanese Department of Agriculture, have reportedly died due to stress-induced conditions within 2 km of turbines. "I have had reports of high levels of stillborn lambs and calves (up to 10%)…and stillborn horses in Australia and overseas, only after wind farms commenced operations," he claims.
Wind farms may even be damaging to the family pet, he believes. "A dog was verified by Werribee Veterinary Hospital as dying from multiple organ fibrosis, believed to be stress-induced—and it was also within 2 km of turbines."
Animals grazing near wind farms have also exhibited fibrosis, or hemorrhaging of major organs, when butchered, he observed. He believes this may explain why some native birds abandon habitat and cease breeding close to wind turbines.
That's of serious concern to Cumming, who has endangered bird species nesting on wetlands at his New Zealand farm.
There have also been claims around the world of human health impacts in some communities near wind farms. Dr. Nina Pierpont, a Johns Hopkin School of Medicine trained physician and Princeton University PhD, has authored a book titled Wind Turbine Syndrome documenting serious health effects in people living near wind turbines due to low-frequency sound waves:
_URL_ The wind industry has disputed her findings.
Cumming seeks residents in East County and elsewhere around the world who live within 5 km of wind turbines to create a large data pool. Participants may already own chickens, or be willing to acquire them for the study. Cutting open a dead hen will expose the shell-less egg, if that is the cause of death, he said.
He seeks the following data:
1. How close the nearest turbines are to your chickens or slaughtered animals
2. How many turbines are within 5 km
3. Brand and size of the turbines
4. Name of the wind farm
5. Your country
Data may be sent to _EMAIL_
East County Magazine is also interested in hearing about local cases of animal hemmorrhaging, wind eggs, or human health issues from people living near wind farms in San Diego's East County: contact _EMAIL_.


text:
Graph-based Semi-Supervised Learning in Acoustic Modeling for Automatic Speech Recognition
MetadataShow full item record
Acoustic models require a large amount of training data. However, lots of labor is required to annotate the training data for automatic speech recognition. More importantly, the performance of the acoustic model could degenerate during test time, where the conditions of test data differ from the training data in speaker characteristics, channel and recording environment. To compensate for the deviation between training and test conditions, we investigate a graph-based semi-supervised learning approach to acoustic modeling in automatic speech recognition. Graph-based semi-supervised learning (SSL) is a widely used semi-supervised learning method in which the labeled data and unlabeled data are jointly represented as a weighted graph, and the information is propagated from the labeled data to the unlabeled data. The key assumption that graph-based SSL makes is that data samples lie on a low dimensional manifold, where samples that are close to each other are expected to have the same class label. More importantly, by exploiting the relationship between training and test samples, graph-based SSL implicitly adapts to the test data. In this thesis, we address several key challenges in applying graph-based SSL to acoustic modeling. We first investigate and compare several state-of-the-art graph-based SSL algorithms on a benchmark dataset. In addition, we propose novel graph construction methods that allow graph-based SSL to handle variable-length input features. We next investigate the efficacy of graph-based SSL in context of a fully-fledged DNN-based ASR system. We compare two different integration frameworks for graph-based learning. First, we propose a lattice-based late integration framework that combines graph-based SSL with the DNN-based acoustic modeling and evaluate the framework on continuous word recognition tasks. Second, we propose an early integration framework using neural graph embeddings and compare two different neural graph embedding features that capture the information of the manifold at different levels. The embedding features are used as input to a DNN system and are shown to outperform the conventional acoustic feature inputs on several medium-to-large vocabulary conversational speech recognition tasks.
- Electrical engineering


, from a knowledge discovery point of view, the reproduction of known knowledge may not necessarily be the intended result.[32]
The F-measure can be used to balance the contribution of false negatives by weighting recall through a parameter \beta \geq 0. Let precision and recall be defined as follows:
 P = \frac {TP } {TP + FP }
 R = \frac {TP } {TP + FN}
where P is the precision rate and R is the recall rate. We can calculate the F-measure by using the following formula:[30]
 F_{\beta} = \frac {(\beta^2 + 1)\cdot P \cdot R } {\beta^2 \cdot P + R}
Notice that when \beta=0, F_{0}=P. In other words, recall has no impact on the F-measure when \beta=0, and increasing \beta allocates an increasing amount of weight to recall in the final F-measure.
 J(A,B) = \frac {|A \cap B| } {|A \cup B|} = \frac{TP}{TP + FP + FN}
 FM = \sqrt{ \frac {TP}{TP+FP} \cdot \frac{TP}{TP+FN} }
where TP is the number of true positives, FP is the number of false positives, and FN is the number of false negatives. The FM index is the geometric mean of the precision and recall P and R, while the F-measure is their harmonic mean.[35] Moreover, precision and recall are also known as Wallace's indices B^I and B^{II}.[36]
Clustering Axioms[edit]
Given that there is a myriad of clustering algorithms and objectives, it is helpful to reason about clustering independently of any particular algorithm, objective function, or generative data model. This can be achieved by defining a clustering function as one that satisfies a set of properties. This is often termed as an Axiomatic System. Functions that satisfy the basic axioms are called clustering functions.[37]
Formal Preliminaries[edit]
A partitioning function acts on a set S of n \ge 2 points along with an integer k > 0, and pairwise distances among the points in S. The points are not assumed to belong to any specific larger set or space; the pairwise distances are the only data the partitioning function has about them.[citation needed] We may label the points in S using the numbers \{1, 2, \ldots, n\}. The pairwise distances define a distance function d: S \times S \rightarrow R which should have the properties of a semimetric: for any i, j \in S, we must have d(i, j) \ge 0, d(i, j) = d(j, i), and d(i, j) = 0 if and only if i = j. In other words, the distances must be nonnegative, symmetric, and two points have distance zero if and only if they are the same point.
A partitioning function F takes a distance function d on S \times S and an integer k \ge 1 and returns a k-partition of S, a collection of non-empty disjoint subsets of S whose union is S. The sets making up the k-partition are the clusters. Two clustering functions are equivalent if and only if they output the same partitioning on all values of d and k.
Now in an effort to distinguish clustering functions from partitioning functions, we lay down some properties that one may like a clustering function to satisfy. Here is the first one. If d is a distance function, then we define \alpha \cdot d to be the same function with all distances multiplied by \alpha.
For any distance function d, number of clusters k, and scalar \alpha > 0, we have F(d, k) = F(\alpha \cdot d, k)
This property simply requires the function to be immune to stretching or shrinking the data points linearly. It effectively disallows clustering functions to be sensitive to changes in units of measurement - which is desirable. We would like clustering functions to not have any predefined hard-coded distance values in their decision process.
The next property ensures that the clustering function is "rich" in types of partitioning it could output. For a fixed S and k, Let Range(F(\bullet, k)) be the set of all possible outputs while varying d.
For any number of clusters k, Range(F(\bullet, k)) is equal to the set of all k-partitions of S
In other words, if we are given a set of points such that all we know about the points are pairwise distances, then for any partitioning \Gamma, there should exist a d such that F(d, k) = \Gamma. By varying distances amongst points, we should be able to obtain all possible k-partitionings.
The next property is more subtle. We call a partitioning function "consistent" if it satisfies the following: when we shrink distances between points in the same cluster and expand distances between points in different clusters, we get the same result. Formally, we say that d' is a \Gamma-transformation of d if (a) for all i,j \in S belonging to the same cluster of \Gamma, we have d'(i,j) \le d(i,j); and (b) for all i,j \in S belonging to different clusters of \Gamma, we have d'(i,j) \ge d(i,j). In other words, d' is a transformation of d such that points inside the same cluster are brought closer together and points not inside the same cluster are moved further away from one another.
Fix k. Let d be a distance function, and d' be a F(d, k)-transformation of d. Then F(d, k) = F(d', k)
In other words, suppose that we run the partitioning function F on d to get back a particular partitioning \Gamma. Now, with respect to \Gamma, if we shrink in-cluster distances or expand between-cluster distances and run F again, we should still get back the same result - namely \Gamma.
The partitioning function F is forced to return a fixed number of clusters: k. If this were not the case, then the above three properties could never be satisfied by any function.[38] In many popular clustering algorithms such as k-means, Single-Linkage, and spectral clustering, the number of clusters to be returned is determined beforehand – by the human user or other methods – and passed into the clustering function as a parameter.
Biology, computational biology and bioinformatics
Plant and animal ecology
clustering is used to build groups of genes with related expression patterns (also known as coexpressed genes). Often such groups contain functionally related proteins, such as enzymes for a specific pathway, or genes that are co-regulated. High throughput experiments using expressed sequence tags (ESTs) or DNA microarrays can be a powerful tool for genome annotation, a general aspect of genomics.
Sequence analysis
High-throughput genotyping platforms
clustering algorithms are used to automatically assign genotypes.
Human genetic clustering
Medical imaging
On PET scans, cluster analysis can be used to differentiate between different types of tissue and blood in a three dimensional image. In this application, actual position does not matter, but the voxel intensity is considered as a vector, with a dimension for each image that was taken over time. This technique allows, for example, accurate measurement of the rate a radioactive tracer is delivered to the area of interest, without a separate sampling of arterial blood, an intrusive technique that is most common today.
IMRT segmentation
Clustering can be used to divide a fluence map into distinct regions for conversion into deliverable fields in MLC-based Radiation Therapy.
Business and marketing
Market research
Grouping of shopping items
World wide web
Social network analysis
Search result grouping
Slippy map optimization
Computer science
Software evolution
Image segmentation
Evolutionary algorithms
Recommender systems
Markov chain Monte Carlo methods
Social science
Crime analysis
Educational data mining
Field robotics
Clustering algorithms are used for robotic situational awareness to track objects and detect outliers in sensor data.[39]
Mathematical chemistry
To find weather regimes or preferred sea level pressure atmospheric patterns.[41]
Petroleum geology
Physical geography
The clustering of chemical properties in different sample locations.
See also[edit]
See also[edit]
Related methods[edit]
 3. ^ Cattell, R. B. (1943). The description of personality: Basic traits resolved into clusters. Journal of Abnormal and Social Psychology, 38, 476-506.
 4. ^ a b c d e f Estivill-Castro, Vladimir (June 2002 2002). "Why so many clustering algorithms — A Position Paper". ACM SIGKDD Explorations Newsletter 4 (1): 65–75. doi:10.1145/568574.568575.
 5. ^ R. Sibson (1973). "SLINK: an optimally efficient algorithm for the single-link cluster method". The Computer Journal (British Computer Society) 16 (1): 30–34. doi:10.1093/comjnl/16.1.30.
 6. ^ D. Defays (1977). "An efficient algorithm for a complete link method". The Computer Journal (British Computer Society) 20 (4): 364–366. doi:10.1093/comjnl/20.4.364.
 7. ^ Lloyd, S. (1982). "Least squares


How a cup of tea can improve your negotiations
Wouldn't it be great if we could improve the way someone is feeling toward us before a negotiation, without them even knowing that we're doing anything? It turns out that there is something we can do, and it could be as simple as offering a cup of tea.
It may sound like an old fashioned way of solving problems. You've lost your job – tell me all about it over a cup of tea. You've had a big argument with your business partner – let's sit down and discuss it over a cup of tea.
While this might just seem like the kind of thing your mum would suggest to make things better, there's research to back up why that cup of tea (or any other hot drink) may well make a positive impact in your negotiations.
Negotiation and the importance of relationship
A key element of each and every negotiation is relationship. In fact, in our workshops, participants often comment that the biggest challenges they face are in managing the relationships with other parties in the negotiation.
The quality of the relationship is determined by the assumptions and perceptions we hold about each other. These fundamentally impact the way we approach a negotiation. If the other person is feeling hostile towards us, the result of the negotiation will be quite different to if they are feeling more positively towards us.
When we find someone to be a "warm" person rather than a "cold" person, we are more likely to have favourable perceptions of them. Psychological warmth is associated with traits such as trustworthiness, friendliness and helpfulness.
So, what can we do to improve the way someone is feeling towards us.
The neuroscience behind warmth and negotiation
puppet stringsResearchers from the University of Colorado and Yale University conducted two studies which demonstrated that it is possible to change a person's impressions and their behaviour, without them being aware of any external influences.
To understand these studies, it is important to know that neuroscientists have discovered that the part of our brain that is involved in processing physical sensations of warmth, is also responsible for processing psychological warmth.
In the first study, participants were primed by being given either a cup of hot coffee or a cup of iced coffee to hold. They were then given a description of a person. Based solely on the information provided, participants had to rate the person on a number of personality traits.
The researchers found that when participants were primed with a warm drink, they rated the person significantly higher in traits relating to warmth. For traits not relating to warmth there was no difference in ratings between the groups primed with hot or cold coffee. Holding the warm drink influenced participants' subsequent interpersonal judgments.
In the second experiment, participants were primed with either a warm or cold therapeutic cushion. They were then given two options:
 - get a bottled drink for yourself and a $1 voucher for a friend; or
 - get a bottled drink for a friend and a $1 voucher for yourself.
The results showed that the temperature priming impacted on how likely participants were to choose a gift for themselves rather than a friend. Twenty five percent of those primed with a cold cushion selected the gift for a friend compared with 54 percent of those primed with the warm cushion.
Put the kettle on for your next negotiation
boiling kettleSo, while we wouldn't recommend relying solely on this phenomenon as a strategy for your next negotiation, it does seem like a good idea so somehow prime your counterpart with a sense of physical warmth. So before your next negotiation, make sure you offer your negotiation counterpart a nice warm cup of tea!
Download our free Harvard-based negotiation planner here to get started. To learn more about interest based negotiation, we recommend the book "Getting to Yes by Roger Fisher & William Ury."
Read more blogs from our experts


09 Mar 2021
ESG seals of approval: navigating financial
sustainability labels
Not unlike the labelling of food products with 'organic' labels, financial investment products with sustainability objectives are now increasingly coming with ESG labels.
Lyxor ETF's Antonio Celeste, ESG Product Specialist, explains how these 'green' and 'ESG' labels can help investors navigate the crowded sustainable investments market with confidence.
How can investors navigate the crowded space of European SRI labels?
In recent years, there has been a strong proliferation of assets in the ESG market, which reflects growing investor sensitivity to ESG (Environment, Social and Governance).
Some European countries have created labels that provide clearer sustainability information for the benefit of investors who are keen to include sustainability factors in their portfolios.
These labels are a powerful tool for both asset managers and investors. Asset managers use them to reinforce their ESG credentials, while investors, who are often overwhelmed by the number of offers they have to screen, have more straightforward options.
Across France, Luxembourg, Belgium, Germany, Austria and Scandinavia, there are two main types of labels: "ESG" and "Green" labels, which focus on climate-related criteria.
The biggest European ESG label in terms of assets under management (at EUR 349 billion) is France's "Label ISR", which was created by the French Ministry for the Economy and Finance in 2016.
France also has the "Green" label – Greenfin (with EUR 14 billion AUM) – which requires funds to have a given percentage of assets directly linked to a set taxonomy of sustainable
activities, while specifically excluding fossil fuels and nuclear power. Greenfin-labelled funds must also have an inbuilt mechanism for avoiding ESG controversies, and must publish reporting and indicators to measure the environmental benefits of the invested assets.
What is the difference between the various European labels?
The French "Label ISR" is different from other European ESG labels. It is based on the ESG score improvement or the exclusion of ESG laggards, and requires that a fund performs better than its reference index on two ESG indicators (i.e. gender balance, carbon emissions, board independence etc…). However, product-related or controversy-related exclusions are not mandatory.
Labels in Germany, Austria and the Nordics do apply exclusions, for example for non-conventional fossil fuels, tobacco, weapons, and other criteria. These labels have a sliding-scale scoring system, showing the degree to which funds apply ESG criteria.
How are these labels evolving to meet growing investor expectations?
Asset managers are pushing for more harmonisation of the different national labels, given that the sustainability expectations of investors tend to be universal.
For example, 10 years ago sector exclusion in ESG funds was uncommon in France, while we now see more and more French asset managers (who tend to apply stricter criteria than demanded by labels) excluding tobacco, alcohol, and controversial fossil fuel-related activities such as coal, shale gas, tar sands and arctic drilling.
Labelled funds have grown significantly in AUM in recent years with the launch of new ESG funds, and will continue to do so. In 2020, the AUM of the French "Label ISR" grew by 153%, and we see similar levels of growth with the Belgian "Towards Sustainability" Label (+ 104%) and the German FNG Siegel Label (+97%).
Lyxor's labelling efforts
We're happy to report that two more ETFs in our ESG range recently received the official SRI Label:
This adds to our growing list of ESG credentials, including the SRI Label for our MSCI Europe ESG Leaders (DR) UCITS ETF and our MSCI EMU ESG Trend Leaders (DR) UCITS ETF, and the Greenfin Label for our flagship Green Bond (DR) UCITS ETF.
Watch this space as we continue with our ESG fund labelling programme throughout 2021 and beyond!
Risk Warning
Research disclaimer
Conflicts of interest


Are Iguanas Semi Aquatic?
Are Iguanas Semi Aquatic? Some marine mammals, such as the marine otter, the polar bear and pinnipeds, are semiaquatic, while others, such as the sea otter, cetaceans and sirenians, are fully aquatic. Marine iguanas and partly marine crocodiles (such as the saltwater crocodile and the American crocodile) are all semiaquatic.
? Other semi-aquatic lizards include the agamid water dragons Physignathus cocincinus (Green or Chinese water dragon), P.
lesueurii (Australian water dragon) and P.
temporalis (Asian water dragon).
Like some varanids, water dragons have a laterally-compressed tail and an opportunistic diet.
Why do iguanas spit? iguanas spit to take out all of the salts from the bodey and The green iguana is designated as least concern according to the International Union for Conservation of Nature (IUCN). They do not have gills, so they can not breath underwater.
Can marine iguanas stop their hearts? While underwater, the reptile's main predators are the sharks who can hear their heartbeats from up to 13 feet away. However, these iguanas are able to voluntarily stop their hearts for up 45 minutes to deter the sharks.
You Might Also Like: How Many Gecko Species Are There?
Are Iguanas Semi Aquatic – Related Questions
Similar words for semiaquatic:
What animals can live in a Paludarium together?
Paludarium Inhabitants
How Do You Talk to an iguana?
How bad is an iguana bite?
Answer: Amphibians utilize gills for breathing early in life, and develop primitive lungs in their adult life; additionally, they are able to breathe through their skin. Aquatic animals may breathe air or extract oxygen that dissolved in water through specialised organs called gills, or directly through the skin.
Is a aquatic?
Are humans still evolving?
You Might Also Like: Are Iguanas Protected In The Keys?
Can humans become aquatic?
Some scientists have hypothesized that humans were once on the cusp of being aquatic. In 1960, marine biologist Alister Hardy suggested a branch of human ancestors may have been forced by competition to leave the trees and live off shellfish by the sea shore.
Do iguanas like to be held?
Why do green iguanas spit?
Some people mistakenly think the iguana is spitting on them, but they should be pleased to know it's just a healthy body function.
Can iguanas learn their name?
They recognize their owners by sight and sound.
Can an iguana kill a cat?
Cats and Lizards or Iguanas
Do iguanas get lonely?
What do marine iguanas do all day?
So what does a marine iguana do in a typical day
How many marine iguanas are still alive?
The total population has been estimated at between 200,000 and 300,000.
The short, blunt nose is well-adapted to feeding on algae growing on rocks.
The flattened tail is perfect for swimming, propelling the iguana through the water while its legs hang useless at its sides.
You Might Also Like: How To Catch A Gecko With Your Hands?
Are moose semi aquatic?


Watch a Pig Decompose Underwater
By Casey Chan on at
Pork is absolutely delicious any which way you cook it, and it seems like sea lice, which are like ocean maggots apparently, would agree too. The sea lice do most of the heavy eating, before shrimp come in to finish the job. It's disturbingly exciting.
Why did scientists throw a dead pig in the ocean? Well, they wanted to get a better idea of how bodies decompose underwater. The experiment, led by forensic scientist Gail Anderson from Simon Fraser University in Canada, shows a pig carcass inside a cage and tracks its entire progress. New Scientist says:
Shrimp come into finish the job but when the scientists retrieved the bones, they were "strangely" jet black for 48 hours. They've never seen that before and are looking at what caused the turn in colour. Watch the video, it ain't pretty. [New Scientist via BoingBoing]


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Non-linear Simultaneous Fitting/Solution
Asked by Avigdor on 6 Sep 2012
 I am trying to model two vector data sets f1(x) and f2(x) using two non-linear equations with common variables.
 For example:
 f1(x) = a0 + a1(k1,t)*exp(-l1*x) + a2(k1,t)*exp(-l2*x)
 f2(x) = b0 + b1(k1,t)*exp(-l1*x) + b2(k1,t)*exp(-l2*x)
 I would like to simultaneously fit f1(x) and f2(x) to these two equations. Then graphically display the data and fits. The a1, a2, b1, and b2 are expressions which are different but contain the variables k1 and t which will be determined from the simultaneous fit. I would like to use matlab script to do this.
 Is fsolve the way to do this? If so, can somebody please give a little direction as to setting this up?
Edit: I have been trying fmincon, but need the minimization to output a global minimum for the vector data sets, not a minimum at each point. Is there a way around this in simple code?
No products are associated with this question.
1 Answer
Answer by Matt Tearle on 6 Sep 2012
Edited by Matt Tearle on 6 Sep 2012
You can treat this as a least-squares problem with 6 parameters: a0, b0, k1, t, l1, and l2. Then make your objective function the total square error ((y1 - f1(x))^2 + (y2 - f2(x))^2). So something like
function err = myerrorfun(c,x1,y1,x2,y2)
f1 = c(1) + [function of c(3) and c(4)]*exp(-c(5)*x1) +...;
f2 = c(2) + [function of c(3) and c(4)]*exp(-c(5)*x2) +...;
err = (y1-f1).^2 + (y2-f2).^2;
Then in your main program, call a minimization routine like fmincon:
x1 =... % enter/load
x2 =... % all
y1 =... % the
y2 =... % data
% make a function handle of one variable (the parameters), with the data embedded
objective = @(c) myerrorfun(c,x1,y1,x2,y2);
% do the fitting
c_fit = fmincon(objective,...);
Avigdor on 9 Sep 2012
Thank you for the information and concise code!
Do you have any suggestions as to estimation of goodness of fit, or error in fit from such a method?
Matt Tearle on 12 Sep 2012
In this case, myerrorfun is actually returning the sum of the squared error. You can get the function value as a second output from fmincon (or whatever minimization function you used). But if you want more detailed info, you could make functions to evaluate f1 and f2; call these with c_fit and x1 or x2; take the difference with y1 and y2 and now you have the residuals. Apply whatever standard analysis you normally would to the residuals of a regression -- hist, normplot, scatter(resids(1:end-1),resids(2:end)), etc. Or, of course, apply your favorite goodness-of-fit formula (eg adjusted R^2).
Matt Tearle
Contact us


Barge with CNG
We have converted several variable speed propulsion systems to dual fuel, often with removable gas storage systems. In the following example a barge with propulsion and auxiliary engines was converted to CNG + dual fuel while operating with jumbo CNG storage skids.
Variable speed engines present additional challenges while operating on Dual Fuel, and fuel performance has to be sacrificed to get proper engine response. However, that being said, Dual Fuel Gas with Diesel engines provide a higher level of fuel flexibility as well as better emissions performance.


text:
The city of Verkhoyansk is located in Yakutia, its north of the Arctic Circle. The city is the third smallest city in Russia. Its population is about 1,400. Temperatures usually can drop to -40°C. The lowest temperature was recorded, which is -69,8°C.
2. Oymyakon, Russia
Oymyakon village is located in Eastern Siberia, Russia. The population of about 600 people and they living literally in the ice caves. The average temperature is -40°C during the winter, which lasts nine months. Oymyakon is located in the taiga between the mountains, which is why there are such low temperatures. The temperature record was -71°C.
3. Yakutsk, Russia
Yakutsk is the capital of the Yakutia region in Siberia with a population of about 200.000. The average temperature in January is about -50°C.
4. Utqiagvik, Alaska
Utqiagvik is officially the City of Utqiaġvik and previously Barrow is the largest city and the borough seat of the North Slope Borough in the U.S. state of Alaska and is located north of the Arctic Circle. Absolute minimum of the tempurature is – 47 °C.
5. Ulan Bator, Mongolia
In Ulan Bator winter begins in November and warming occurs only at the end of March. The mark of the thermometer in this period of time is often fixed at — 50 °C.
The minimum was recorded at -32°C, and the average annual temperature in winter is kept at -8.1°C. From full freezing Nuuk save warm current, and the houses in the town are painted in different colors, which allows people to avoid depression during the long and cold polar night.
7. International Falls, USA
The city in the North of the United States in Minnesota, the administrative center of Koochiching County. The average temperature in the winter months is -21°C and the absolute minimum was -48.3°C.
8. Vostok Station, Antarctica
The place is a small town consisting of several complexes, including residential and research modules, as well as technological buildings. Absolute maximum od tempurature is – 14 °C. in January, minimum: – 90°C in July.
9. Snag, Canada
The lowest temperature was in 1947, and it was equal to -62.8°C. Interesting fact that the average temperature in winter is around -12°C, and in summer it does not exceed 1.2°C.
10. East Antarctica
Also known as Greater Antarctica, East Antarctica is the coldest region in the world. It constitutes the majority (two-thirds) of the Antarctic continent. It is colder than west Antarctica. It lies on the Indian Ocean side of the Transantarctic Mountains.


text:
SK181N Lasers and Applications 6.0 cr
KTH has developed a net based course in physics for those who want to know more about laser physics and its modern applications within optical communication, laser fusion, laser welding, lasers within environmental science. The course fits with those who have studied basic courses in physics and mathematics.
The development within the modern laser physics and its applications within front line research such as laser fusion, holography, optical communication, laser measurements of the ozone layer at the height of 30km, as well as ultra fast laser pulses with laser shots that are more than 1000 million times faster than modern digital cameras.
We, and our computers, communicate by using laser beams traveling through optical fibers. Modern home electronics often consist of solid state lasers. The development within laser technology is thrilling. You might also feel that it is fun to test your physics skills and investigate how it works to study via the internet together with thousands of other students.Perhaps you have started a technical/natural science education and want to broaden your knowledge within physics.
The course is divided into two parts and you can study them in a flexible way at your own speed. The course is completely net based.
|Weeks||Application code||Application on antagning.se||User account|
|02-13||V13_20043||Application closed||User account|
The course will not be given during summer or autumn 2012


Why do we go to church on Sunday LDS?
Why do we go to church on Sunday instead of Saturday?
Why do Mormons keep Sunday?
In The Church of Jesus Christ of Latter-day Saints, Sunday is a sacred day. It is the Sabbath day, a day that we worship the Lord. … And on the seventh day God ended his work which he had made and he rested on the seventh day from all his work which he had made.
IT IS INTERESTING: Where in the Bible does it talk about the Christmas star?
What can LDS do on Sunday?
Here are seven things to do with the extra hour not in church on Sunday.
 - Family history. Buy Now. …
 - Hiking in nature. Alexander Ishchenko. …
 - Visit family. Stock. …
 - Take a nap. Getting enough sleep is always important. …
 - Family games. …
 - Watch conference talks or Mormon Messages.
Is the Sabbath day Saturday or Sunday according to the Bible?
Is Sunday worship biblical?
What religions dont work on Saturdays?
Jews don't work on Saturdays and many Christians don't work on Sundays.
What day of the week is the Mormon Sabbath?
In most areas of the world, this means worship on Sunday, though there is adaptation for Israel and many majority-Muslim countries. In harmony with this revelation, members of the LDS church attend sacrament meeting each week.
Do Mormons celebrate Christmas?
What do the Mormons believe?
IT IS INTERESTING: What does the Bible teach about vulnerability?
What is the Mormon temple used for?
The temple is the most sacred space of the Mormon faith. It's used for ordinances, or events, for Mormon families who wish to become closer to God. The small rooms cater to baptisms, weddings, meditation and sealings, a ceremony in which a husband, wife and sometimes children commit to one another even after death.
What day is the seventh day of the week?
What does the New Testament say about keeping the Sabbath day holy?
The full text of the commandment reads: Remember the Sabbath day, to keep it holy. Six days you shall labor, and do all your work, but the seventh day is the Sabbath of the LORD your God. … Therefore the LORD blessed the Sabbath day and made it holy.
Catholic Church


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The Thomas-Fermi equation with dimensionless variables is identified as; $$ \frac{d^2\phi}{dx^2} = \frac{\phi^{3/2}}{x^{1/2}} $$ with the boundary conditions as $$ \phi(0) = 1 \\ \phi(\infty) = 0. $$ There are many series approximation solutions available to this equation. I am interested in finding the integral representation for the solution of this differential equation. Are there any literature sources available in this direction?
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Related: math.stackexchange.com/q/806472/11127 – Qmechanic May 26 at 18:00
1 Answer 1
You have lectures notes on Density Functional Theory by Andrei Postnikov that may answer your question, in particular chapter 1 eq (1.16) _URL_ it is
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Loren on the Art of MATLAB
Indexing Terminology 11
Posted by Loren Shure,
Someone recently asked me to discuss X-Y versus row-column indexing.
Two Conventions
When calling functions in MATLAB that create or reference arrays, there are two different conventions for specifying the first two dimensions of an array:
 - matrix indexing, i.e., rows and columns
 - Cartesian, i.e., X and Y
These different conventions get used depending on whether the array is strictly an array or when it has a probable physical interpretation in terms of Cartesian grid.
Matrix versus Cartesian Frameworks
In MATLAB, we index into matrices using row and column indices. That is, for matrix
A = magic(3)
A =
 8 1 6
 3 5 7
 4 9 2
I can reference the last element in the second row like this:
ans =
ans =
and to retrieve the first element of columns 1 and 3, I type this:
A(1,[1 3])
ans =
 8 6
Check out this post to get a fairly complete picture of indexing in MATLAB.
Plotting Matrices
The options xy and ij for axis allow us to control whether to view the data just the way the matrix is displayed (the (1,1) element is in the upper left corner):
or we can view the image/matrix as a top-down view of a physical "map" with the y-values now increasing along the vertical axis.
axis xy
In images, the matrices column values plot vertically. In line plots, the columns are plotted vs. their indices, making columns plot horizontally.
h = plot(A);
legend(h,{'Column 1','Column 2','Column 3'})
Creating an N-Dimensional Grid
ndgrid uses matrix indexing since it is designed to suit working in any number of array dimensions.
[ii, jj] = ndgrid(1:3,1:2)
ii =
 1 1
 2 2
 3 3
jj =
 1 2
 1 2
 1 2
Creating an 2- or 3-Dimensional Grid
On the other hand, mesh, interprets its first inputs in a Cartesian framework since it is used primarily for working with 2- and 3-dimensional plots, often depicting something over an area or volume.
[xx, yy] = meshgrid(1:3,1:2)
xx =
 1 2 3
 1 2 3
yy =
 1 1 1
 2 2 2
In the Remarks section of the documentation for meshgrid, you will find a discussion of this, especially with respect to inverting the first two input arguments compared to ndgrid. There is related discussion in the Description section for the function mesh.
Functions designed for two or three dimension, such as contour and quiver, usually work in Cartesian coordinates. Functions that are designed to work in N-dimensions generally work with a matrix indexing framework. Be sure to check the help for functions you use to see which convention applies.
Any ideas on what we can do, perhaps in examples or documentation (or eslewhere?) to help people out with this potential confusion? If so, please post here.
Get the MATLAB code
Published with MATLAB® 7.4
11 CommentsOldest to Newest
I encountered this ambiguity just this week using contourf(). My contours kept coming out just the opposite as what I expected. It wasn't until I tried plotting a non-square matrix before I realized something was wrong.
My suggestion to MATLAB is to pick a convention and stick with it.
Which convention to choose? And why that one? Both are natural in different situations. Hence the dilemma.
I personally usually think of "meshgrid" as the worst Matlab function – note that I do enjoy most of them.
I have my own imho-owell-oriented meshgrid function, with a different name, but some functions such as interp2 (TBC) require the grid to be meshgrid-generated!
This change of convention is a nightmare. As an image processing engineer, I find it so easier to keep the same convention : x goes with row index, hence row index is a natural discretization of x direction, while y goes with column index.
Obviously the obtained Cartesian grid is not in the usual direction (north to south for X and west to east for Y), but it makes a lot of computation so easier – especially when going from continuous to discrete representations, which is when hard things usually begin (think of a warping between two images, for instance).
I think it is easier to rotate the Cartesian coordinate system, in order to have a consistent (i,j) and (x,y) notation. It keeps both the axes direct (angles in the right directions) and the matrix multiplication (IDL convention is a nightmare).
Anyhow, this is my Humble Opinion – Keep the good work!!
(hi Loren, I am one of the Toulouse guy: it was nice meeting you!!)
I read and re-read this column several times over the past few days and I'm still confused. I regularly use indexing in MatLab and find that it very powerful tool in writing compact, easy to understand code.
But this xy option is very confusing to me. I had never previously noticed the xy option in the axis function and based on this column, I took some time to try to understand the value or benefit of that option. I also tried to follow your example regarding ndgrid and found myself bumping up against one of the few serious limitations within MatLab. That is MatLab's poor capability regarding table lookups. In the past when I've tried to figure out how to use interpn, I've been tripped up by the example in the function reference page that uses ndgrid. There is something fundamental about the ndgrid function that I'm not getting and I wonder if it is related to this ij vs xy concept.
I'm with Jessee above, pick a standard and stick with it. Just because MatLab can provide alternate ways to do things doesn't mean that there is a benefit to the alternate way. My experience is that the indexing method is widely used in MatLab so that should be the standard.
Maybe you need to write a detailed column that goes beyond the single example in the function reference page for ndgrid and also provides a proper description of the ndgrid function. e.g., the description says that it transforms the domain specified by the vectors into arrays. But, it doesn't say how they are transformed.
Anyway, after all this, I still don't understand what the significance is for this xy indexing.
I was most interested in the use of the commands image and imagesc to plot the values of items in matrices.
I had been using pcolor along with 'shading flat' to achieve almost the same effect. The problem with doing this is that in plotting the contents of an n x n array, you get a figure with an (n-1)x(n-1) array of elements, the last row and column being ignored.
I would like to use image instead of pcolor for my applications (using 'axis xy' to preserve orientation), but for one small hitch. pcolor treats NaN's as blanks whereas image and imagesc treat them as zeros. I need them to be treated as blanks, so I keep using pcolor. A further problem with using pcolor is that I don't find the ticklabels line up nicely with the centers of the colorblocks as they do in the magic square example above. Loren, please help. is there anything I can do?
I realize that one workaround is to add an extra row and column to my array of data, but this seems like an ugly hack.
More details: all the data in my matrix is positive integers, so another workaround is for me to convert all the NaN's to zeros before using 'image'. The problem now becomes that the zeros (which I want to ignore) show up in the colorbar.
I have exactly the same problem as Roy Goodman has. I'm surprised that Roy's email was posted only recently (I started using Matlab a year ago). Most of the matrix data I want to display have some NaN elements in them. Is it possible to add another 'property' and 'value' pair to specify the color for displaying the NaN elements in a matrix?
You might try this code (using the opengl renderer, which MATLAB will do automatically with the transparency – though there are bugs in various opengl drivers and they don't all look the same).
A = magic(3)
AA = A
AA(1) = NaN
imalpha = ones(size(A));
h = image(AA), colorbar
imalpha(isnan(AA)) = 0
If your picture doesn't look right, close your figure and use this command first:
opengl software
and then retry. The graphics will be a bit slower but will tend to overcome hardware opengl issues typically.
Glad to find this discussion: whilst meshgrid and its family are excellent starting points for regridding (2D) "images", when volumes or time varying volumes appear, then ndgrid must be used. OK, so far, but then we find that stream3, streamtube etc require meshgrid. Meshgrid for 3D data (e.g. look at "wind" in the examples)? Why oh why oh why?
So, here's the solution I request.
If GIVEN some volume data (e.g., "wind") which has mesh


text:
Date of Award
Bachelor of Arts (Psychology) Honours
School of Psychology and Social Science
Computing, Health and Science
Dr Ken Robinson
Dr Ricks Allan
Fluid intelligence and working memory has been improved by training on a visual working memory n-back task (Jaeggi, Buschkuehl, Jonides & Perrig, 2008). The present study investigated whether n-back training can improve visual memory using a test of visual recognition. A sample of 47 participants were trained for 20 days on either the single n-back task (n = 26) or a general knowledge and vocabulary task (n = 21). The results showed that training using the single n-back task did not significantly increase scores on a test of visual recognition when compared with general knowledge and vocabulary training. However, when initial scores were compared with final scores at completion of the training period, participants who had a high gain in scores on the vocabulary training task improved their visual recognition scores significantly more than those participants who had a low gain in scores on the vocabulary training task. This pattern was not repeated for those participants who were trained in the n-back task. During debrief, participants in the high gain vocabulary training group described shape recognition strategies which they used to improve their performance. It was concluded that the vocabulary task was more successful at training visual recognition than the n-back task which suggested the vocabulary task had a confounding effect on the results of this experiment.
Prandl, A. (2012). Visual memory improvement in recognition. Retrieved from _URL_


Artillery Row
Braving the woke mob is a prisoner's dilemma
Nicholas Shackel, a Professor of Philosophy at University of Cardiff, explains how to turn the prisoner's dilemma into the free speaker's game
In a discussion with Eric Weinstein, Douglas Murray said that if everyone stood up to the woke mob then its power would be broken. True, but there is a reason everyone doesn't: braving the woke mob is a prisoner's dilemma and consequently the rational choice is to keep quiet. This week, Eton beak Mr Knowland didn't realise that he was Head Master Mr Henderson's fellow prisoner.
A prisoner's dilemma is the name for a certain pattern that one may be confronted with in choosing under uncertainty where the outcome depends on both your choice and someone else's. Such patterns are called games in rational decision theory and this one gets its name from the choice that may face criminals.
The only solution to the prisoner's dilemma is to change the game by changing the outcomes
You and your fellow thief have been arrested and are questioned separately. You are both made the following offer: if you confess and your fellow doesn't, you will go free; if you don't but your fellow does, you'll go to prison for 16 years. If you both confess, you'll both get a reduced sentence of 8 years. If neither confesses then they will only be able to convict you on a lesser charge and you'll both go to jail for 4 years. You have no means of communication with your fellow thief. Plainly, you prefer freedom (A) to 4 years jail (B), which you prefer to 8 years jail (C), which in turn you prefer to 16 years jail (D). Moreover, in each case, since you prefer none to 4 and 4 to 8, you prefer none to 8, and so on, which means you satisfy the rational requirement of having transitive preferences.
We assume everyone involved is rational, so that they will choose to do what they prefer. So, what really matters here is the pattern of preference. Here is a table that shows the pattern, where the left-hand column lists your actions, be Silent or Confess, and the top row is your fellow's actions. In the body of the table the first outcome is yours and the second is your fellow's.
You can do nothing about what your fellow thief will do and you do not know what he will do. If he remains silent, since you prefer A to B, you prefer to confess. If he confesses, since you prefer C to D, you again prefer to confess. So, whatever he does, you prefer to confess. So you confess.
This reasoning is in accord a principle of rational decision called dominance. If there is a single choice which you prefer, whatever choice your partner makes, that choice is called the dominant choice and dominance says you should choose it.
The temptation at this point it to think about loyalty and threats. And that is quite correct, but the important thing to realise is that such moves are not, strictly speaking, solutions to prisoner's dilemma but ways of changing the game. For if loyalty and threats change your choice, they change outcomes by making confession worse than 16 years jail, for example, by calling confessors snitches and adding assassination to the outcome. This gives us an entirely different pattern and therefore an entirely different game:
Now, whatever your fellow thief does, you prefer to remain silent, so you remain silent.
There is a literature that attempts to prove it to be rational for both to remain silent but all such attempts amount to covert changes of the game. The criminals are right: the only solution to the prisoner's dilemma is to change the game by changing the outcomes, and so to prevent it being played against you by the police. That is why we strengthen the game by offering you witness protection: provided there is inadequate loyalty, it removes the threat and confines the outcomes to the question of freedom and jail alone. This is why it is important to ensure the outcomes are fully specified.
Strictly speaking, our analysis has confined itself to two people. From hereon, and without going into the additional complications needed for the strict treatment of many people, I shall be taking advantage of an ambiguity, that you may be individual or several and so may your partners. As will become evident, the pattern is sustained over pairs of peoples just as well as over pairs of people.
Now let us consider braving the woke mob. We all know the rules now: if you stand up, you'll be mobbed on Twitter, you will be vilified publicly, the lying slanders may be believed and your reputation destroyed, and you may lose your job. But exactly what the outcome will be also depends on how others act.
Democracy has freed us to take the transgressors to their inquisition in 280 characters
If you Stand on your own and those who are your partners chicken out, you will be the Heretic cast out. If you Chicken out while leaving, or even throwing, your Stand-up partner to the mob, you are safe or (thanking the mob, with perhaps some hesitations over their tone) Virtuous in your superior woke orthodoxy. If you and your partners all chicken out, checking your privilege and confessing to your sin, you are an orthodox Sinner who may hope for redemption. If you and your partners Stand together, you will be vilified as Blasphemers but may escape the penalties of heresy. So anyone standing up faces the unbeliever's dilemma:
Currently, our society has decided to reward people with this preference order: the Virtuous (A) are better than Sinners (B) are better than Blasphemers (C) are better than Heretics (D). On this ordering, the unbeliever's dilemma is the prisoner's dilemma. If the other stands, you prefer to chicken out and if they chicken out you prefer to chicken out, so whatever they do, you prefer to chicken out and chickening out is dominant.
This is the game Mr Knowland and Mr Henderson played: Mr Knowland Stood and Mr Henderson Chickened out and displayed his woke Virtue, and our society ruled the first the Heretic and the second the Virtuous. Of course, it is a little more complicated than that, but we know the list of recent players of this game. Whilst there are many who disagree with the naming and ordering of outcomes, it remains the case that the heretics were all successfully slandered, anathematised and lost jobs and the various authority figures they played the game with, being at best the useful idiots of the woke, Chickened out and displayed their woke virtue.
What needs to happen is for the game to be changed to the free speaker's game:
You may think it obvious what this game prescribes, but again, it all depends on the preference order. The religious have always, and, as we have just seen, continue to identify the truth seeker with the blasphemer and heretic and the dogmatist with the virtuous, which leaves us all chickening out with the dogmatists. The religious then add the extra burdens to the outcomes to get to the unbeliever's dilemma as a prisoner's dilemma.
We face the woke prisoner's dilemma and it remains rational to chicken out
The historical precedents do not give grounds for optimism about such a change: from Socrates' apology on, the record shows the religious imposing the prisoner's dilemma on the would-be free speaker. Nevertheless, were it to be widely recognised that this, rather than the woke prisoner's dilemma, is the true game to be played, Mr Henderson would have to resign. Unfortunately, so would the various authorities across the country, who have played this game for their own purposes. They are skilled at trimming and don't care to distinguish the falsehoods of the woke creed from the moral truths there are about freedom and equality. Whilst that remains the case, we face the woke prisoner's dilemma and it remains rational to chicken out.
Interestingly enough, the righteous also face a dilemma. Let us join them. All around us we see, or perhaps seek out, wilful transgression. Democracy has freed us to take the transgressors to their inquisition in 280 characters. You may Damn them or Bewail your injury. If you call down damnation but your partners bewail, you will have shown your partners to be Saintly Victims at the price of being a Bully. If you and they bewail, lacking the revelation of the transgressor's sin, you are merely Whiners. If, however, you and they call down damnation, you are the Virtuous joined in the righteous defence of the wronged. Thus we have the dilemma of the righteous:
Saints are better than the Virtuous, who are better than Whiners, who are better than Bullies. On this preference order, the dilemma of the righteous is, once more, a prisoner's dilemma. If your partner damns, you prefer to be a Saint than Righteous, so you bewail, and if your partner bewails, you prefer to be a Whiner than a Bully, so you bewail. So whatever your partner does you prefer to bewail, so you bewail. How is it, then, that the righteous ever turn damnation into a joint venture?
Of course, for any of the righteous who would rather bully than whine, and who are impatient of sainthood, they will prefer to damn whatever their partners do, so that might explain it. But unless there are enough of them, they are in danger of appearing as no more than a gang of extremist thugs. Few are willing to view or show themselves in that light and in general the righteous aspire at least to


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Mental Health First Aid
Mental Health First Aid (MHFA) is a 12-hour training certification course designed to give members of the public key skills to help someone who is developing a mental health problem or experiencing a mental health crisis. Research evidence demonstrates that participating in the course improves knowledge of mental health conditions, reduces stigma, and increases the amount of help provided to others—helping the public identify, understand and respond appropriately to signs of mental illness. Like CPR training helps a non-medical professional assist an individual following a heart attack, Mental Health First Aid training helps an individual who doesn't have clinical training assist someone who's experiencing mental health difficulties.
Mental Health First Aiders learn to apply a single strategy in helping someone through a panic attack, engaging with someone who may be suicidal, supporting a person experiencing psychosis and helping an individual who has overdosed.
The MHFA five-part action plan is known as A-L-G-E-E:
A ssess for risk of suicide or harm
L isten non-judgmentally
G ive reassurance and information
E ncourage self-help and other support strategies
E ncourage appropriate professional help
The National Council for Community Behavioral Healthcare, the Maryland State Department of Health and Mental Hygiene, and the Missouri Department of Mental Health worked with the program's founders to bring Mental Health First Aid to the U.S. and now administer its operation in this country.
DBSA is proud to offer Mental Health First Aid training courses by using teams of consumers—the ultimate experts in the experience of mental illnesses and substance use—and clinicians to train key members of the public in Mental Health First Aid skills. This partnership between those who live with these conditions and those who seek to support their recovery adds immeasurably to the legitimacy and power of this public education effort. For more information on Mental Health First Aid, visit _URL_
Two Ways to Participate
Join Our Peer Partnership Mailing List


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- To review colours and practise describing the colours of things.
- To practise describing a person's appearance.
Here are some of the frequent words used in this lesson that have appeared in previous lessons. Using the flashcards, check that you remember their meanings.
In Lesson 27 you learned the main words for colours. You are about to fine tune your command of these terms, so review Lesson 27 first to make sure you can automatically produce them. Here are two ways you can talk in a more nuanced, more precise way about colours.
1. In Indonesian, dark colours are "old" (tua) and light colours are "young" (muda).
|Blusnya kuning tua.
Her blouse is dark yellow.
|or||Blusnya berwarna kuning tua.
Her blouse is dark yellow in colour.
|Atap rumahnya biru muda.
His house has a blue roof.
Atap rumahnya berwarna biru muda.
2. In English you can use the suffix "-ish" to describe something that has a certain hue or tinge, for example "reddish", "greenish", "yellowish" etc. In Indonesian you produce a similar effect by 1 reduplicating the adjective and 2 nesting it between the affixes keand –an.
He has reddish hair.
Orang yang mempunyai penyakit hati kulitnya menjadi kekuning-kuningan.
A yellowish skin tone develops in people suffering from liver disease.
Here are some of the very common adjectives that can be used to talk about someone's appearance. (You have met and practised some of them already.) Check that you know the meanings of all of them.
|Someone's general proportions||tinggi, pendek, besar, kecil, biasa|
|Someone's general appearance||cantik, ganteng, jelek, biasa, kurus, gemuk|
|The appearance of someone's hair||botak, panjang, pendek, lurus, keriting|
|The colour of someone's hair||hitam, pirang, putih, kemerah-merahan, coklat tua|
|The colour of someone's skin||putih, kuning langsat, sawo matang, hitam manis|
|The colour of someone's eyes||hitam, coklat, biru, kehijau-hijauan|
Translate these sentences into good Indonesian. Remember two things: 1. with a tiny number of special exceptions, the adjective follows the noun in Indonesian, and 2. "to have" is often expressed with the possessive suffix –nya. First check the model below.
Cue sentence: She has very long hair.
You write: Dia itu rambutnya panjang sekali.
or (more commonly) Rambutnya panjang sekali.
Imagine that you are a police officer (polisi). You have to describe a fugitive criminal (penjahat) to journalists, to the public or to fellow police officers. Your description should cover sex, age, place of origin, height, whether the person is fat or thin, hair colour, eye colour, complexion and what the person is wearing. Your description might begin like this (as you repeat the role play, you should radically vary this opening):
Selamat pagi (siang/sore/malam) Bapak-Bapak dan Ibu-Ibu. Nama saya Ridwan. Saya kepala kantor polisi di sini. Kami sedang mencari seorang penjahat dari Wonosobo bernama Joko yang dicari karena mencuri mobil. Dia berumur kira-kira 25 (dua puluh lima) tahun. Tinggi badannya 170 (seratus tujuh puluh) sentimeter dan agak gemuk. Dia berkulit sawo matang dengan rambut lurus dan pendek. Ia memakai kemeja lengan pendek, (etc. etc. etc.) ….
The police officer should conclude by saying something like this:
Saya minta tolong kepada Bapak-Bapak dan Ibu-Ibu kalau melihat orang ini, segera hubungi kami di nomor _PHONE_ (dua empat lima tujuh dua tujuh delapan). Terima kasih. Ada pertanyaan?
The "audience" now quizzes the speaker, asking for clarification and more details. There are many kinds of questions you can ask, but two important ones that relate to recent lessons are:
1. use memakai to ask about what the fugitive is/was wearing. For example
2. Use –nya constructions to ask about what kind of personal features and clothes the fugitive has. For example
|Joko itu||rambutnya keriting?|
|Apakah||penjahat itu||berbaju biru?|
'Light Red' is, as we have learned above, merah muda. More common, however, is it to refer to a pinkish colour with the term merah jambu. Jambu air is the name of the fruit very closely related to the Malay apple, which in Hawai'i is known as the mountain apple. The fruit with the Latin name Syzygium aqueum is juicy and slightly sweet-sour and is often part of the spicy fruit salad called rujak.
Of course you should also try to re-cycle all the kinds of questions you have practised so far, for example questions beginning with:
Di mana ….
Siapa yang ….
Hari apa / Tanggal berapa / Jam berapa / Kapan ….
Apakah ada ….
and many more.
The prefix berforms intransitive verbs (that is verbs that cannot take an object) such as berangkat (to leave), bekerja (to work), berhenti (to stop), belajar (to study), berenang (to swim), bertemu (to meet), berpikir (to think), berdiri (to stand), berbelanja (to shop), bersiap-siap (to get ready), beristirahat (to rest), bersisir (to comb).
A large group of berverbs is based on nouns and has the general meaning "to have/own [base]":
bersuami to have a husband
berumur be aged
bernama be named
beranak have children
berguna to be useful
berhasil to have success, to succeed
A subgroup of this group means "to use, wear, travel by [base]":
bertopi to wear a hat
berdasi to wear a tie
bersepatu to wear shoes
berkacamata to wear glasses
berbaju to wear a shirt
berkuda to ride a horse
bersepeda to ride a bicycle
Adjectives or possessive nouns can be added:
berkacamata hitam to wear sunglasses
berbaju biru to wear a blue shirt
bertopi koboi to wear a cowboy hat
bersepeda balap to ride a racing bike
Instead of using berone can of course also use memakai or naik:
Anak itu berkacamata minus. / Anak itu memakai kacamata minus.
That child wears minus (myopic) glasses.
Toni setiap hari bersepeda ke kantor. / Toni setiap hari naik sepeda ke kantor.
Every day Toni goes to his office by bike.


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Aerodynamic drag is the resistance (retarding effect) applied to a body as it passes through the air. It is made up of two components, caused by pressure and by friction. Resistance caused by pressure occurs because there is a difference in air pressure between the front and rear surfaces of the body. This has to be overcome to keep the body moving through the air, and is particularly significant in the case of relatively flat-surfaced, bulky objects such as motor vehicles. If the body moving through the air is slim and streamlined, however, like a modern aircraft, resistance due to friction represents a higher proportion of total aerodynamic drag. It is caused by the airflow rubbing against the surfaces as it passes over them.
Aerodynamic drag increases at the same rate as the square of the air speed. In other words if the speed doubles, the drag increases fourfold; if it quadruples, it increases sixteen-fold. See also: cd value.


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Next Generation Blood Gas Monitors System Market: Overview
The next generation blood gas monitors are the devices that are used for observing the level of carbon dioxide tension, arterial oxygen tension, and acidity. By checking these parameters diagnosis of the disease becomes easy. The condition may be a shock, pulmonary disorder, overdose of certain drug, etc. The next generation blood gas monitors are fundamental devices that are present in the CCU and ICU rooms. There are many technological advancements done in this field.
Next Generation Blood Gas Monitors System Market: Segmentation
The global market for the next generation blood gas monitors system is fragmented into its product type, end user, and application. On the basis of the product type, the market is segregated into portable and bench top. On the basis of end user, the market is categorized into hospitals, clinical laboratories, cardiac centers, and others. On the basis of application, the market is divided into combined and single next generation blood gas monitors.
Next Generation Blood Gas Monitors System Market: Growth Factors
The major factors that are favoring the growth of the next generation blood gas monitors are the increased rate of the hospital admissions, the growing number of the geriatric population, and the rise in the prevalence of the chronic diseases. The other factors that are influencing the growth of the next generation blood gas monitors systems market in the coming years are the increasing healthcare expenditure and the development of the advanced technologies. The factors that are affecting the market growth in a negative way are the stringent regulatory protocols in some of the nations and the rise in the cost of the point of care devices.
Next Generation Blood Gas Monitors System Market: Regional Analysis
The geographical diversification of the global next generation blood gas monitors system market includes Asia Pacific, North America, the Middle East and Africa, Eastern Europe, Latin America, and Western European regions. The region that is leading the next generation blood gas monitors system market is North America. Europe is following North America in terms of market growth. The factors that are contributing to the market growth in these regions are the increased technological advancements, highly developed healthcare infrastructure, and the increased number of the market players. Increasing number of the product innovations that are made in this field is also supporting the growth of the market. It has been observed that the next generation blood gas monitors that are available in the regions of North America and Western Europe have the capability to incorporate with the EMR system of the hospital which helps in improving the work flow. The market in Asia Pacific will grow at a significant rate due to the increasing aging population and the rise in the cases of chronic diseases.
Next Generation Blood Gas Monitors System Market: Competitive Players
The key market players that are involved in the next generation blood gas monitors system market include Bayer, Convergent Technologies, Alere, Inc., Roche Diagnostics, Samsung Medison, Nova Stat, Alere, Medica, Radiometer Medical, Abbott Point of Care Inc., Nova Biomedical, Siemens Healthcare, Erba, Edan Instruments, and Dalko Diagnostics.
Next Generation Blood Gas Monitors System Market: Regional Segment Analysis
What Reports Provides


A subspace of $\mathbb R^n$ is compact if and only if it is closed and bounded in the Eulidean Metric or Square Metric or $l_1$ metric.
Is my statement correct?
Actually the statement - "A subspace of $\mathbb R^n$ is compact iff it is closed and bounded in the Euclidean Metric or Square Metric" was given in Mukresh. I think closed and bounded set in the $l_1$ metric would also be compact. As the topologies of three are same.
Am I correct? Please correct me if I am wrong.
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 $\begingroup$ Yes, the $\ell_1$ metric is equivalent to the euclidean metric. This follows from simple arithmetic inequalities. Moreover, there is only one norm-induced topology on R^n. $\endgroup$ – Lorenzo Quarisa Apr 8 '18 at 12:45
 - $\begingroup$ I did not get you _USER_...All I want to know is whether my statement is correct or not. $\endgroup$ – cmi Apr 8 '18 at 12:50
 - 1
 $\begingroup$ The only compact subspace of $\mathbb R^n$ is the trivial subspace (consisting solely of the zero vector, one point). I'm concerned that you meant to ask about characterizing which subsets of $\mathbb R^n$ are compact rather than which subspaces are compact. But the statement is true (what applies to all subsets certainly applies to subspaces). $\endgroup$ – hardmath Apr 8 '18 at 12:56
 - $\begingroup$ yes..You are correct..But why Mukresh used Subspace?_USER_ $\endgroup$ – cmi Apr 8 '18 at 12:59
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 $\begingroup$ Context matters. If one speaks of Euclidean space $\mathbb R^n$, most often one is thinking about it as a vector space that has a topology. In a general topology text one may instead think of the subsets of a topological spaces as inheriting a subspace topology, so I'm open to the author using "subspace" to mean topological subspace rather than vector subspace. $\endgroup$ – hardmath Apr 8 '18 at 13:04
As the topologies induced by the $\ell_1, \ell_2$ and $\ell_\infty$ metric are the same on $\mathbb{R}^n$, closedness under one of them is equivalent to closedness under any other of them.
Also, all these metrics are related by inequalities:
$d_1(x,y) \le d_2(x,y) \le \sqrt{n} d_\infty(x,y); d_\infty(x,y) \le d_1(x,y)$ etc. so that boundedness in one of them also implies boundedness in all others.
So the compactness characterisation holds in all 3 of the metrics, in fact in any metric derived from a norm. The topology being the same is not enough, as the truncated metric $d_{t}(x,y) = \min(d(x,y), 1)$ induces the same topology as $d$ does, but in $d_t$ all sets are bounded, while this need not hold for $d$. So one does require an argument to see that the combination of closedness and boundedness for a specific metric is preserved.
Your Answer


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Climate change poses the greatest threat to medium sized predators such as foxes as it forces them to spend more time hunting for food, British researchers found.
Medium-sized carnivores which generally weigh between one and ten kilograms, are more vulnerable because they spend the most time foraging.
As the climate affects their prey they must spend more time hunting to survive, scientists said.
And they found failing to diversify their prey could put the species at greater risk of climate change.
Ecologists had previously believed foraging time decreased as animal size increased, but the team discovered that wasn't the case.
Co-author Dr Chris Carbone, from the Zoological Society of London, said: "Medium-sized predators are forced to search for food for longer periods of time on a daily basis because they tend to feed on prey that are small compared to their own size.
"Prey that are much smaller than a predator are hard to find and catch, and therefore do not easily satisfy the predator's energy needs and provide insufficient 'bang for the buck'."
The research, published in the Nature Ecology and Evolution journal, looked at previous studies of 73-species of land-based carnivore.
Activity data was gathered using tracking methods including radio collars and GPS, then a mathematical model was used to predict the risk of climate change on each.
Species ranged from small predators like weasels to some of the largest, such as tigers, and the scientists found the medium-sized spent the greatest part of their day foraging.
Other examples of mid-size predators included the Malay civet and Iriomote cat.
Study co-author Dr Samraat Pawar, from Imperial College London, said: "We propose a simple mathematical model that predicts how foraging time depends on body size.
"This can help predict potential risks to predators facing environmental change.
"Habitat changes can mean that predators have to move more to find the same amount of food, causing them greater stress.
"This impacts the health of the individual, and therefore the health of the population.
"Our approach could be used to better understand the diets of other groups of species as well improving our knowledge of threats of climate change and habitat loss in a wider range of species."
Co-author Matteo Rizzuto, formerly a Master's student in the Department of Life Sciences at Imperial, said each species' vulnerability will also depend on the kind of prey they feed on.
He added: "If they are able to adapt their diet and diversify their prey, they may fare better."


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Ash tree
Ash is the name of three very distinct group of trees. In America and Europe, "ash" generally refers to trees of the Genus Fraxinus. In Great Britain, "ash" also refers to the mountain ash or Rowan, Genus Sorbus. In Australia, "mountain ash" refers to a type of eucalyptus, Eucalyptus regnans, one of the tallest trees in the world (perhaps second only to the coast redwood).
Table of contents
1 Ash Genus: Fraxinus
2 Cultural aspects
Ash Genus: Fraxinus
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Scrophulariales *
Family: Oleaceae
Genus: Fraxinus
 Fraxinus americana -- white ash
 Fraxinus angustifolia -- narrowleaf ash
 Fraxinus anomala -- single-leaf ash
 Fraxinus apertisquamifera
 Fraxinus caroliniana -- water ash
 Fraxinus cuspidata -- fragrant ash
 Fraxinus dipetala -- two-petal ash
 Fraxinus dubia
 Fraxinus excelsior -- common ash
 Fraxinus baroniana
 Fraxinus bungeana -- Bunge ash
 Fraxinus chinensis -- Chinese ash
 Fraxinus chiisanensis
 Fraxinus floribunda
 Fraxinus gooddingii -- Goodding's ash
 Fraxinus greggii -- Gregg's ash
 Fraxinus griffithii
 Fraxinus holotricha
 Fraxinus hubeiensis
 Fraxinus lanuginosa
 Fraxinus latifolia -- Oregon ash
 Fraxinus longicuspis -- Japanese ash
 Fraxinus malacophylla
 Fraxinus mandshurica -- Manchurian ash
 Fraxinus micrantha
 Fraxinus nigra -- black ash
 Fraxinus ornus -- flowering ash
 Fraxinus papillosa -- Chihuahua ash
 Fraxinus paxiana
 Fraxinus pennsylvanica -- green ash
 Fraxinus platypoda
 Fraxinus profunda -- pumpkin ash
 Fraxinus purpusii
 Fraxinus quadrangulata -- blue ash
 Fraxinus raibocarpa
 Fraxinus rufescens
 Fraxinus uhdei -- Shamel ash
 Fraxinus sieboldiana -- Chinese
 flowering ash
 Fraxinus spaethiana
 Fraxinus trifoliata
 Fraxinus velutina -- velvet ash
 Fraxinus xanthoxyloides -- Afghan ash
*Some botanists include the Oleaceae
in the order Lamiales.
The Genus Fraxinus is in the olive family (Family Oleaceae). Ashes are usually medium to large trees. Most have pinnately-compound, opposite leaves. Seeds are borne in keys, a type of fruit known as a samara.
The white ash is a particularly important timber tree in eastern North America, and is the source of wood for quality wooden baseball bats. The green ash is widely planted as a street tree in the United States. The inner bark of the blue ash has been used as a source for a blue dye.
Ashes of eastern North America include:
Ashes of western and southwestern North America include:
Ashes of Europe include:
Ashes of Asia include:
Ashes of Africa (North Africa only) include:
Cultural aspects
Norse mythology, the World Tree, Yggdrasil, was an ash tree, and the man, Ask, was formed from an ash tree (the first woman was made from alder). Elsewhere in Europe, snakes were said to be repelled by ash leaves or a circle drawn by an ash branch. Irish folklore claims that shadows from an ash tree damage crops. In Cheshire, it is said that ash could be used to cure warts or rickets.
See also; Trees of Britain, Trees of the world