Slimey Likes It! Studying Chemotaxis in Physarum Polycephalum
Time Required Long (2-4 weeks)
Prerequisites An introductory course in chemistry would be useful.
Material Availability You will need to order the "Chemotaxis in Physarum" kit online; see the Materials and Equipment list for details. This item may have to be ordered by your teacher.
Cost Average ($50 - $100)
Safety Be careful working with sharp blades. Adult supervision is recommended.
Explore chemotactic responses of P. polycephalum in culture exposed to various amounts of glucose.
David B. Whyte, PhD, Science Buddies
The procedure is modified from Bozzone, D. M. 2005. Using microbial eukaryotes for laboratory instruction and student inquiry. Retrieved December 18, 2009 from _URL_
Cite This Page
MLA Style
Science Buddies Staff. "Slimey Likes It! Studying Chemotaxis in Physarum Polycephalum " Science Buddies. Science Buddies, 4 Sep. 2013. Web. 28 July 2014
APA Style
Science Buddies Staff. (2013, September 4). Slimey Likes It! Studying Chemotaxis in Physarum Polycephalum. Retrieved July 28, 2014 from _URL_
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Last edit date: 2013-09-04
If you have walked through a wooded area that's still damp from a recent rain, you may well have seen a Physarum growing on a tree stump or among the fallen leaves. Members of the genus Physarum are also called slime molds. Slime molds are classified with protists. More than 700 different species of slime molds exist. They have a two-part life cycle. During warm, moist weather, a slime mold lives as a shapeless, growing blob called a plasmodium. The plasmodium may be gray, cream, colorless, bright yellow, or orange. A plasmodium slowly creeps across the ground, moving like an amoeba and consuming bacteria, fungi, and organic debris as it moves. When the environment dries out, the plasmodium transforms into many small, often stalk-like, fruiting bodies that are full of dust-like spores. The tiny spores can remain dormant in the soil for years, waiting for wet weather, at which time they release small, motile (capable of movement) cells. Two motile cells fuse together and grow to become a new plasmodium, starting a new cycle of life.
In order to survive, a Physarum plasmodium searching for food has to respond appropriately to environmental cues. It is constantly "deciding" which way to move: toward areas that will have food or away from areas that contain harmful substances. Part of the "input data" the plasmodium relies on to make this kind decision is based on chemical cues. If the organism senses chemicals that indicate the presence of food, it will move toward the area with more of that chemical. If it senses chemicals that are harmful, it will move to avoid further contact. Movement in response to a chemical signal is called chemotaxis.
Because chemotaxis is easy to observe and measure in Physarum, you can investigate various factors that affect it. In this biology science fair project, you will determine how the chemotactic responses of a Physarum polycephalum (P. polycephalum) plasmodium growing in culture depends on the concentration of glucose.
Terms and Concepts
 - Physarum
 - Slime mold
 - Protist
 - Plasmodium
 - Fruiting body
 - Environmental cue
 - Chemical cue
 - Chemotaxis
 - Physarum polycephalum
 - Millimolar concentration
 - To what other environmental cues do you think a moving plasmodium might respond?
 - How many species of Physarum are found in the state in which you live?
 - Based on your research, what are the various stages in the Physarum's life cycle?
 - If you go to the kitchen when you smell something cooking, is that an example of chemotaxis?
Materials and Equipment
 - Chemotaxis in Physarum polycephalum Kit. The kit contains the following:
 - Physarum culture, as plasmodium on agar plate
 - Petri dishes
 - Non-nutrient agar
 - Oatmeal flakes (Physarum "food")
 - Filter paper
 - Aluminum foil
 - Beaker, 250 mL
 - Graduated cylinder, 10 mL
 - Graduated cylinder, 100 mL
You will also need to gather these items:
 - Microwave
 - Oven mitt
 - Plastic knives (1 box)
 - Ruler, metric
 - Plastic cups (12)
 - Permanent marker
 - Distilled water (1 gallon)
 - Glucose tablets, 4 g/tablet; available at most drug stores or online at Amazon.com.
 - Scissors
 - Forceps or tweezers
 - Lab notebook
 - Optional: Digital camera
 - Graph paper
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Experimental Procedure
Working with Biological Agents
Important Notes Before You Begin:
 1. Be sure you thoroughly read the procedure before beginning so you know how much time each step will take and can plan your schedule accordingly.
 2. Follow the steps below to make culture plates of Physarum for your experiments. The cultures will be grown on agar, and then transferred to fresh agar plates when the Physarum covers the old plate. The goal is to establish a healthy stock of growing plasmodia for your experiments.
Culturing the Physarum
 1. Loosen the top of a bottle of non-nutrient agar.
 2. Heat the non-nutrient agar in a microwave until it is liquid. Use an oven mitt to remove it if the bottle is hot.
 3. Pour the agar into 10 petri dishes so that the bottoms are covered.
 4. Let the agar harden.
 1. For long-term storage, wrap the petri dishes in their plastic sleeves and store them in a refrigerator until you are ready to use them.
 5. Put on your disposable gloves. Count out 25 sterile oatmeal flakes for each agar surface and place them on top of the agar.
 6. Cut out a piece of agar with plasmodium attached from the Physarum polycephalum culture that came with the kit. Read the following before you begin:
 1. Use a plastic knife.
 2. The piece should be about 1 cm by 1 cm.
 3. Place the agar block, with the plasmodium facing down, on one of the agar plates (which are the petri dishes now containing agar) that you made in steps 3–5.
 4. Place a lid on the plate.
 7. Wrap the plate in aluminum foil.
 8. Monitor the culture daily, until you see enough growth. Use your judgment.
 1. To keep the culture healthy, transfer the culture to fresh plates (the additional ones you made in steps 3–5) every 3–4 days. To transfer to fresh plates, follow steps 6–8 of this section, except cut out a piece from your culture, not from the kit.
 2. To dispose of older cultures, wrap them in aluminum foil and place them in your regular garbage.
 3. Begin your experiments once you have established a stock of growing Physarum cultures.
Making Solutions with Varying Concentrations of Glucose
 1. Label five plastic cups: 100, 10, 1.0, 0.10, and Blank.
 2. Place a glucose tablet in the cup labeled 100 and add 222 mL of water using the 250-mL beaker.
 3. Let the tablet of glucose dissolve completely.
 1. This is a 100-mM solution.
 - mM stands for millimolar. It is a way of measuring the concentration of an ingredient in solution. For more information about molarity, see the reference by Uri Lachish in the Bibliography in the Background.
 2. The solution may be slightly hazy due to additives in the tablet. You can ignore this.
 4. Make a 10-mM solution:
 1. Use the cup labeled 10.
 2. Mix 10 mL of the 100-mM solution with 90 mL of distilled water.
 3. Use the 10-mL graduated cylinder and the 100-mL graduated cylinder to measure volumes.
 4. Mix the solutions in a clean plastic cup.
 5. Thoroughly wash the graduated cylinders between uses.
 5. Make a 1-mM solution.
 1. Use the cup labeled 1.
 2. Mix 10


A JOY-filled Christmas Visit – Deric Bartlett
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Sermon Notes
This week, Pastor Deric continues the series "Christmas Visits" with a message titled 'A JOY-filled Christmas Visit' based on Luke 1:39-45
 1. JOY in community (v. 39-40)
 2. JOY in the Holy Spirit (v. 41)
 3. JOY in the Good News (v. 42-43)
 4. JOY in His presence (v. 41, 44)
 5. JOY in believing (v. 45)
ICEBREAKER: What is the best pair of shoes you have owned?
1.What news prompted Mary to make the 3-day journey to the hill country town in Judah [Luke 1:39]? How did the report of Elizbeth's pregnancy [Luke 1:36-37] encourage Mary's faith [cf. Genesis 18:14; Jeremiah 32:17; and Matthew 19:26]?
2.What did the baby's leap in Elizabeth's womb signify [Luke 1:41]? How did this foreshadow the child's future [cf. Matthew 11:7-14; Luke 1:13-17; and John 1:6-8]?
3.What does it mean when someone is "filled with the Spirit" [Luke 1:41]? Is it a legitimate experience? Is it limited to certain special believers, or all believers [cf. Acts 6:5; Acts 11:23-24; and Ephesians 5:18-21]?
4.What does Elizabeth's question in Luke 1:43 indicate about her character, as well as her understanding of the true identity of Mary's Child [John 20:28; Romans 12:3; and Philippians 2:3]?
5.Why do you think joy was linked to the arrival of Christ [Luke 1:44]? Why is joy lacking in our world, and how does Jesus inspire it [cf. Isaiah 61:1-4; Luke 2:10-14; and Luke 24:38-41]?
6.What is the connection between believing the Word of God and being blessed by God [Luke 1:45]? Consider Joshua 1:8; Psalm 1:1-2; and James 1:22-25 for more insights.
7.What did you find helpful or challenging about this Sunday's message?


Ends in -PTION
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DefinitionWordLetter before the P
A title or explanation for a picture or illustrationa
An instance or case not conforming to the general rulee
The act or faculty of apprehending by means of the senses or of the minde
The quality or fidelity attained in getting radio or television broadcastse
A fit of hysterical excitement or angeri
A note, as a dedication, that is written and signed by hand in a booki
A direction by the physician to the pharmacist for the preparation and use of a medicinei
Outlawry, interdiction, or prohibitioni
The failure of a legacy because the subject matter no longer belongs to the testator's estate at deathm
Something taken for granted; a suppositionm
The using up of goods and services having an exchangeable valuem
DefinitionWordLetter before the P
The circumstances of a taxpayer that allow him or her to make certain deductions from taxable incomem
Courage; spunk; gutsm
The act or right of claiming or purchasing before or in preference to othersm
Belief on reasonable grounds or probable evidencem
Atonement for guiltm
The act or fact of taking up or going on with again, as of something interruptedm
The act of putting something into a more inclusive classificationm
To legally assume the role of parent to a childo
Something that may be or is choseno
A taking in or reception by molecular or chemical action, as of gases or liquidsr
The accumulation of gases, liquids, or solutes on the surface of a solid or liquidr
The movement of substances from the blood into the lumen of the gutr
Moral perversion; depravityu
An issuing forth suddenly and violentlyu
Cessation; intermissionu
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Think your children are bird-brains? You're right - our feathered friends outperform seven-year-olds in logic tests
- Eurasian jays outperform 7-year-olds in logic tests
- Birds do better than humans in two out of three tests
By Fiona Macrae
In two of the three tests, the birds ¿ Eurasian jays ¿ did just as well as the seven-year-old children
IT'S a suggestion that will give pause for thought to even the proudest of parents.
For no matter how bright they believe their son or daughter is, until the age of seven, children are, at least in some respects, no brainier than birds.
In simple experiments, birds did just as well as children up until the age of seven.
Researchers pitted birds against boys and girls using tests inspired by the Aesop's fable in which a thirsty crow is able to drink from a pitcher after using pebbles to raise the water level to within its reach.
In two of the three tests at Cambridge University, the birds – Eurasian jays – did just as well as the seven-year-old children.
After this, the human mind proved superior to the bird brain.
The experiments built on earlier work in which jays quickly learned that adding stones to a cylinder half-filled with water would bring a tasty treat floating on the surface within reach of their beaks.
In a second task the jays – colourful members of the crow family and about the same size as jackdaws – realised it was better to use pebbles, which sink, than corks, which float.
When Cambridgeshire children, aged four to ten, were set similar tasks, they did as well as the jays on the first, up to the age of seven.
Brainy boy? Up until the age of seven, children are, at least in some respects, be no brainier than birds
From the age of eight, the pupils
learned more quickly than the birds. The pattern was similar with the
second task – except four-year-old children did worse than the jays.
However, a third, more complex, task separated the youngsters from the birds.
It again involved dropping objects into water to raise its level. But this time, a U-shaped tube was used, with the join at its bottom hidden, giving the impression it was two separate tubes.
It meant dropping a stone into one 'tube' led to the water rising in the 'other' – a counter-intuitive result.
This appeared to confuse the birds. However, the children did as well as before, the journal PLoS ONE reports. The researchers said this shows children are better at putting preconceptions aside.
Lucy Cheke, a PhD student, said: 'It is a child's job to learn about the world. They can't do that if they're limited by a preconceived idea about what is or is not possible.
'For a child, if it works, it works. The birds, however, found it much harder to learn what was happening because they were put off by the fact it shouldn't be happening.'

source: HuggingFaceFW/fineweb-edu


text:
Too much residual starch in bran means foregoing profit for millers. Bühler offers two ways out of the 'residual starch dead end' with its online measuring technology: the NIR Multi Online Analyzer MYRG or the Online Color and Speck Measurement MYHB. Both methods measure and report an increase in residual starch without loss of time making prompt correction possible.
Bühler AG – Grain Milling
In the grain milling industry the term extraction rate describes the amount of flour that can be made from 100 kg of grain. In modern milling operations, yield calculators continually monitor production and determine the degree of extraction. The goal of every miller when producing white, low-ash flour is to separate as much of the endosperm from the husk (bran) as possible. Bran is considered a by-product in milling and can be used as an additive for feed or sold as is.
OPTİMUM EXTRACTION RATE
Flour particles that stick to the bran as residual starch in the separation process are considered a loss by the miller. The higher the extraction rate, the higher the yield and thus also the miller's profit. However, it should be noted that as the extraction rate increases, more edge and husk particles are released from the grain along with the flour starch. With a higher extraction rate, the flour becomes darker and has a higher ash content. Millers will do everything they can to achieve the optimal extraction rate based on the desired type of flour and customer requirements. This includes trying to avoid too high of a residual starch content in the bran which means lower yields. Of course, other parameters which influence the baking properties must also be taken into consideration.
But how can the miller determine whether 'his' bran has too much residual starch? An initial indication is that yield drops or the ash content in the flour is low. If the miller determines this is true, he can use polarimetric starch determination according to Ewers (ISO 105020:1997) in the lab to determine the residual starch content in the bran. This method dissolves the raw starch in the test sample in hot, diluted hydrochloric acid. After precipitation of the spurious substances, the optical rotation of the raw starch solution is polarimetrically measured and the starch content is calculated based on the rotation angle. This is an old method and has its pitfalls: A conventional value results because other optically active carbohydrates (particularly water soluble ones) can be detected as well. It is also time-consuming and requires chemicals which is why very few millers use this method regularly. Sometimes the samples are sent to an external laboratory. The reverse way is also a possibility: The ash in the bran is measured. Most millers simply eyeball whether there is too much starch in the bran - the lighter it is, the more residual starch it contains.
CHANGING THE GRINDING GAP
What should the miller do when he determines that there is too much residual starch in the bran? An immediate measure is to check the back passages in the grinding process and see if the rollers are too high and thus the grinding gap too large. If that is not the case, the overall settings for the passes are not right. For instance, if the grinding gap in the front passes is too big, then the back passages are overloaded. They will not be able to loosen the remaining residual starch. In this case, checking the overall settings of all roller mills becomes inevitable.
ONLINE MEASUREMENT TECHNOLOGY
Bühler offers two ways out of the 'residual starch dead end' with its online measurement technology: the NIR Multi Online Analyzer MYRG or the online color and specks measurement MYHB. Both online methods are suitable for determining the residual starch in bran. The quantitative NIR method aims for a high degree of conformity with the official reference method ISO 105020:1997. Its use is particularly recommended if a NIR Multi Online Analyzer MYRG is already present in the mill. In this case, an additional NIR sensor is sufficient. The color and specks measurement MYHB is used when there is no MYRG system available. It can be a cost-effective alternative to qualitative monitoring of the bran.
How much can the yield be increased if the residual starch in the bran is permanently monitored online? Statistics show: For a well-managed mill, yields can be increased by about 0.5%. For a poorly managed mill, improvements in yield can be up to 3%.
What does that mean from a financial point of view? Let's assume that the mixing bran has a residual starch of 19%. With proper intervention, this can be reduced to 16%. The 3% residual starch recouped corresponds to a total yield of 0.66% at a bran yield of 22%.
If a ton of wheat is ground, the final measurement is an additional 6.6 kilograms. These 6.6 kilograms, as part of the bran, have a value of 0.60 euros but, as flour, it can be sold for 2.64 euros. The difference for the miller is 2.04 euros per ton. If the mill capacity is 220 t/24 hrs., that is an additional revenue of 450 euros per day or 160,000 euros per year.

source: openbmb/Ultra-FineWeb


Using WeDo 2.0 Across the Curriculum
By Nick Acton
10 Topic Teaching Opportunities
It has never been more important for school's to get everything they can possibly get out of their chosen educational resources. When the budget comes in and the catalogue comes out, a budget stretching jigsaw puzzle begins to be constructed. We can buy that if we don't buy this. We can get more of those if we get less of these. We can't buy that all together! This mind-boggling budget battle can be beaten. Ultimately, any and every resource must be seriously analysed for its usability. The question is, how much can we get from this?
LEGO® Education WeDo 2.0 kits can offer more than you might think. Of course, the main reason for a WeDo 2.0 kit's existence is to provide meaningful Programming and Computing experiences. However, the functionality and usability of the technology can have an enhancing baring on all sorts of curriculum areas. Integrating the WeDo 2.0 into wider planning can enrich the curriculum and deepen a learners understanding of any given topic.
Amazingly, LEGO® Education offer an unparalleled amount of free lesson plans and resources. As part of this, they have released a 42-page Teacher Guide on Computational Thinking and 24 Guided/Open Projects available on the WeDo 2.0 app. I know what you're thinking… Who has the time to read through a 42 page PDF and 24 digital projects? As much as we would like to widen our understanding of using WeDo 2.0, we would never find the time to get through it all.
Not to worry! We've had a go at filtering through the fantastic free resources for you! In this blog, I will look at common Primary Teaching Topics and explain how the WeDo 2.0 can be integrated into them in a meaningful way. I'll point you directly to the Guided/Open Projects you'll need to visit and essentially, explain how you can get the most out of your technological resource.
1) Space
Exploring the deepest reaches of our galaxy can be an incredibly immersive experience. Imagine adding the experience of building a Moon Base with your own robot!! With WeDo 2.0, you can. Guided Project 17 (Moon Base) takes the children through how to build and programs their own Moon Rover that can complete simple building tasks. The links to science and mathematics are obvious. However, this stimulus could be the platform for historical space race learning. It could spur on some creative writing. Before you know it, the classroom can become a moon base!
Odoo • Image and Text
2) Dinosaurs
Another widely embedded topic concentrates on Dinosaurs! It can capture most children's imaginations. Open Project 11 (Extreme Habitats), explores the exceptional environment of the Jurassic era. Children can use WeDo 2.0 to explore how ancient reptiles evolved to survive. Using the Programming to spur on Geographical study and Biological understanding can provide another angle for a teacher to tackle the subject with.
3) Recycling
Recycling can be a hard subject to teach. LEGO® Education have provided you with an interesting route into the topic. Through Guided Project 8 (Sort to Recycle), learners can explore how rubbish is sorted to aid in reducing the amount of waste that is discarded by building and programming their own sorting machine. The scientific and mathematical links are fairly obvious, however, engaging in this task will also have barring on PSHE. The question of 'why' it is important to recycle can bring up all sorts of important discussions about society and citizenship.
4) Toys
Early on in Key Stage One, children will no doubt learn about toys. Whilst, I feel that anything you do with LEGO® would fit within this topic, the WeDO 2.0 kit can offer a more directly relatable task. Within the 'Getting Started' projects on the app, children can have a go a Milo's Tilt Sensor. This is a very simplistic task that will see the children build a basic robot (Milo) and make it move with a 'tilt sensor'. The result is a roaming robot that functions like a remote control car. In turn, this could be a spring board for conversations about old and new toys; the science of speed and friction; simple instruction tasks as well as the obvious mathematical links.
5) Natural Disasters
Amazingly, the WeDo 2.0 kit can provide meaningful educational experiences around the Topic of Natural Disasters in many different ways. Guided Project 3 (Robust Structures), enables the children to build earthquake simulators. Guided Project 6 (Preventing Flooding) gives the children a detailed understanding of how to reduce the impact of water erosion.
Guided Project 7 (Drop and Rescue) gives valuable insight into how rescue teams deal with the aftermath of a Natural Disaster and drop materials into dangerous areas. Open Project 13 (Hazard Alarm) and Guided Project (Volcano Alert) do exactly as you would imagine. Picking any of these projects can have meaningful links to Science, Geography and History as well as providing further awareness about the harsh reality of Natural Disasters.
Odoo • Text and Image
6) World War Two
The Second World War provides an enlightening backdrop for all sorts of learning. The WeDo 2.0 can make a good contribution to the topic by adding some morse code into the mix. By programming the little light on the WeDo 2.0 and adapting the speed of the flashing via a lever, children can send communication signals. Guided Project 19 (Send Messages) guides the children through the task and teaches them how to dot and dash out letters. Children can use this stimulus to translate messages that were sent during the Second World War. The subject of communication can then be a platform for wider social discussions around freedom of speech and so on.
Odoo • Text and Image
Odoo • Image and Text
7) Under the Sea
Another nice topic that many schools pursue revolves marine life. Learning about the unexplored depths of the sea can be enriched by Open Project 14 (Cleaning the Oceans). This project teaches children about the importance of keeping our oceans clean by tasking them to create a device that can collect rubbish from the surface of the water. Again, the scientific aspects of this project are fairly apparent. However, mathematics plays an important role in the task.
The device will have to size up the materials which will take a fair knowledge of shape and volume. Geography and Social Studies can also be meaningfully interwoven into this kind of project.
8) Animals
Like the topic of 'Natural Disasters', WeDo 2.0 provides many opportunities for cross-curricular learning within the subject of Animals. Guided Task 4 (Frog's Metamorphosis) teaches children about the life cycle of a frog through programming.
Open Projects 9 and 10 (Predator and Prey / Animal Expressions) teach children about the relationships between animals and animal communication respectfully. Finally, Open Project 24 (Animal Senses) deepens a learners understanding of how animals perceive the environment around them. Ultimately, this kind of learning can provide a higher level of understanding of animal biology. However, the subject has a baring on Geography as well.
Odoo • Image and Text
9) All About Me
Many schools opt to cover a very inward-looking topic, often called, All About Me. Key Stage One (usually), think about themselves and in particular their emotions. What makes them happy and what makes them sad. Open Project 22 (Emotional Design) might just provide a platform for many children to begin expressing themselves. The project tasks children to build and program a robot that can interact with people.
Through this, they will explore how robots can create positive emotions in everyday situations. This self-reflection has an obvious connection to PSHE but I would also say that it has a baring in Science as well as being a good platform for (even very young) children to discuss the advancement of technology within our world.
10) Ancient Greek
Finally, I want to visit the topic of Ancient Greeks. It's widely known that the Ancient Greeks are responsible for some of the most fundamentally important inventions and discoveries of our time. Some of the deepest thinkers of science, mathematics and philosophy are associated with Ancient Greek History. It's important to explain to children that programming is all about Problem Solving. Traffic Lights are programmed to solve the problem of traffic. Sat Navs are programmed to solve the problem of Navigation.
Odoo • Text and Image
I could go on. Inventing programs to solve problems is very similar to inventing devices or processes. Therefore, engaging children with a blank programming project and posing a problem is meaningfully linked to Ancient Greek thinkers. Can the children build a robot that moves an object from one side of the room to another? Can the children build a device that flashes at them every time someone walks into the room? Can they make a shutter that dispenses Hamster food to the classroom pet every hour? Being inquisitive and creative is the next logical step for any WeDo 2.0 use. Although all of the aforementioned projects incite creativity in some way, starting with a blank project demands the deepest thinking skills.
Nick Acton is a Trainer Specialist at JTRS as well as being a part-time Computing and Music teacher. Through the creation of bespoke training, Nick specialises in empowering educators so they can embed education technologies into their day-to-day classroom practice.
If you


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This web page contains links to documentation, source code, and input data for the stand-alone version release of CLM2.1. Links to the CAM2.0.1 (Community Atmosphere Model) stand-alone version release and coupled CCSM2.0.1 (Community Climate System Model) release can be found at the bottom of the page.!!NOTE!!: This code currently does not work with CAM2.0.1, however, a new release of CAM (CAM2.0.2) incorporating CLM2.1 is imminent.
CLM2.1 incorporates new hierarchical subgrid data structures and produces only roundoff level changes when compared to CLM2.0.
In what follows, we provide a brief summary of the new CLM2.1 data structures. The subgrid hierarchy in CLM2.1 is composed of gridcells, landunits, columns and plant functional types (pfts). Each gridcell can have a different number of landunits, each landunit can have a different number of columns and each column can have multiple pfts. This results in efficient memory allocation, and allows for the implementation of many different types of subgrid representation.
The first subgrid level, the landunit, is intended to capture the broadest spatial patterns of subgrid heterogeneity. These broad patterns include the physically distinct surface types that were treated as special cases in the previous versions of CLM2.0 (e.g. glaciers and lakes). In terms of CLM2.0 variables, the central distinguishing characteristic of the landunit subgrid level is that this is where physical soil properties are defined: texture, color, depth, pressure-volume relationships, and thermal conductivity. In CLM2.1, landunits are used to represent the special landcover types (e.g. glacier and lakes), with a single additional landunit for the gridcell vegetated area.
The second subgrid level, the column, is intended to capture potential variability in the soil and snow state variables within a single landunit. The central characteristic of the column subgrid level is that this is where the state variables for water and energy in the soil and snow are defined, as well as the fluxes of these components within the soil and snow. Regardless of the number and type of pfts occupying space on the column, the column physics operates with a single set of upper boundary fluxes, as well as a single set of transpiration fluxes from multiple soil levels. These boundary fluxes are weighted averages over all pfts.
The third and final subgrid level is referred to as the plant functional type (pft), but it also includes the treatment for bare ground. It is intended to capture the biophysical and biogeochemical differences between broad categories of plants, in terms of their functional characteristics. All fluxes to and from the surface are defined at the pft level, as are the vegetation state variables (e.g. vegetation temperature, canopy water storage, and carbon and nitrogen states for the leaf, stem, and roots).
In addition to state and flux variable data structures for conserved components at each subgrid level (energy water, carbon, nitrogen, etc.), each subgrid level also has a physical state data structure for handling quantities that are not involved in conservation checks (diagnostic variables). For example, soil texture is defined through physical state variables at the landunit level, the number of snow layers and the roughness lengths are defined as physical state variables at the column level, and the leaf area index and the fraction of canopy that is wet are defined as physical state variables at the pft level.
This subgrid hierarchy is implemented in CLM2.1 as a set of nested derived types. Extensive use is made of pointers, both for dynamic memory allocation and for simplification of the derived type referencing within subroutines. The use of pointers for dynamic memory allocation ensures that the number of subgrid elements at each level in the hierarchy is flexible and resolved at run time, thereby eliminating the need to statically declare arrays of fixed dimensions that might end up being sparsely populated. The use of pointers for referencing members of the derived data type within the subroutines provides a coherent treatment of the logical relationships between variables (e.g., the user cannot inadvertently change a pft-level variable within a subroutine that is supposed to operate on the column states and fluxes), and a more transparent representation of the core algorithms (it is easy to tell when the code is in a column or pft loop).


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The Tin Can Cooker is a homemade outdoor stove that really works. Generations of Scouts have learned to make and use "Buddy Burners" for camping and emergencies. Instead of wood or liquid fuel, the Tin Can Cooker burns a small can of wax and cardboard. A larger can fits over it and holds your cooking pot. Each wax can should burn an hour or more. Make several so you always have one on hand.
1. Curl up strips of cardboard and fit them loosely inside each of your small cans. Leave enough space for wax. Or you can cut short strips and arrange them to form a star that divides the can into pie-shaped slices. The cardboard will act as a wick to get the wax burning across the top of the can. Set the prepared cans on a protected surface, such as a cookie sheet covered in newspaper or aluminum foil. Place it close to where you'll be melting the wax.
2. Break up wax or candles to fit into the top pan of the double boiler. Fill the bottom pan about halfway with water. Fit the top pan into it so it sits above the water. If you don't have a double boiler, set a medium-sized saucepan so it sits over a larger saucepan of boiling water. Turn the stove on medium to heat the water to a steady boil. Let the wax melt until it is completely liquid.
3. Carefully pour the melted wax into the prepared cans. Leave the top edge of the cardboard sticking up above the level of the wax. If your wax starts to harden as you're pouring it, just reheat it to melt it again. Let cool until hardened.
4. Take the large can and remove the entire top with a can opener.
5. Hold the large can with the open end pointing away from you. Take the church key can opener and make 3 or 4 openings at the closed end, around one side, about 1″ apart.
6. Turn the large can so the opening is toward you. You have two options for letting air in at the bottom to feed the flames:
If you don't have tin snips: Use the church key can opener to punch holes all around the open end of the can, about 3″ apart. Take a pair of pliers and fold up the sharp points of metal created by each hole and squeeze them flat.
If you do have tin snips: Create a flap that acts like a fireplace damper to control the airflow. The more oxygen, the higher the flames. Put on heavy work gloves to protect your hands from sharp metal edges. Use the tin snips to cut 2 slits into the side, about 3″ inches long and 3″ apart. Then grab the edge of the can between the slits and bend it outward to make the flap.
7. To use your stove, place the wax can on a flat, nonflammable surface, like a stone paver. Light the cardboard strips, like lighting the wick of a candle. You want the flame to cover the entire top of the can.
When the wax can is lit, adjust the flap on the large can and place it over the smaller can so the holes on the top are facing away from you. (This keeps smoke from blowing in your face.) Now you can cook on top!
Safety Tips for Tin Can Cookery
Tin Can Cookers use an open flame. They can be dangerous, so be sure to follow these safety rules!
- Adult supervision is needed to make and use a Tin Can Cooker.
- Wear heavy gloves when handling cut-metal edges.
- Always keep an eye on melting wax and on the lit cooker. Do not leave them unattended.
- Do not melt wax in the microwave or directly on the stove. Always use a double boiler (or make one from two saucepans).
- Always use hot pads or oven mitts to handle hot pots. Use metal tongs to adjust the cooking can or the wax burner.
- Make sure to use your Tin Can Cooker on a level, fireproof surface, such as a flat paving stone. Watch out for hot liquid wax in the burner — avoid spilling it.
- Do not pour water on burning wax. Use a brick or a metal lid to cover the wax can and smother the flames.
- Tin can cookers can blacken cooking utensils with soot from the burning wax, so don't use them with your best pots and pans.
- Pick up a camping skillet and spatula or small, sturdy garage sale pots and pans and save them just for outdoor cooking.
- Use nonflammable oven mitts and a pair of pliers if you need to adjust the flap while the stove is in use.
- The entire tin can stove gets hot, so never touch it with bare hands while it is lit!
Your Tin Can Cooker is perfect for traditional outdoor fare like grilled cheese and egg-in-a-hole. Find those recipes and more in my book Edible Inventions: Cooking Hacks and Yummy Recipes You Can Build, Mix, Bake, and Grow.


Tuesday, March 31, 2009
Replacing Windows Applications – the Safe Way
[This post courtesy of Ian Prest]
Many folks are probably familiar with the System Internals Process Explorer, which enables users to see all the processes on the system, and provides much more detail than the built in Task Manager that comes with Windows.
One of the neat features of Process Explorer is the option to replace Task Manager so when you (or the system) launches Task Manager, Process Explorer opens instead:
You may also notice that once you have replaced it, that you can simply un-replace it. You might think that under the covers this is replacing taskman.exe with procexp.exe. It is not. Windows Protection will replace procexp.exe with taskman.exe at it's next available chance. What Process Explorer is actually doing, is "faking" to debug Task Manager.
This is a much better way to replace applications in Windows, because it doesn't actually touch the original executable. Instead it launches the "debugger" application and passes in the path to the original executable as the first argument. Process Explorer just swallows this argument and launches itself instead.
So let's say that you're more of a fan of Notepad2 instead of Notepad (due to the awesome text highlighting), and you'd rather windows launch Notepad2 instead of Notepad when opening things in clear text. You can manually do what Process Explorer does programmatically.
Warning: Editing the Registry can cause serious problems and the utmost care should be taken. I am not responsible for a broken machine.
Here is how we can do this. Assuming you downloaded and installed Notepad2, follow these steps:
 1. Open Regedit, and navigate to this location: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\
 2. Create a new KEY for the name of the executable, for example "Notepad.exe" (without the quotes).
 3. In this new Key, create a new string value called "Debugger" without the quotes, and give it the value of the path to Notepad2. E.g. "c:\Program Files\Notepad 2\Notepad2.exe"
At this point you can run "Notepad.exe" and you'll notice that Notepad2 opens with all sorts of garbage in it. This is because Notepad2.exe is passed the path of Notepad.exe, and Notepad2 is opening Notepad.exe for editing. Clearly we don't want this, so we can use a "/g" which is a Notepad2 command to go-to line.
 1. Change the "Debugger" string to "c:\Program Files\Notepad 2\Notepad2.exe /g"
Now Notepad2 will be launched with the command to go to line "c:\windows\notepad.exe" which it translate to line 0, and you have a blank document. Voila!
Moral of the story, if you can tell the application your launching to ignore the argument after it, you can launch the application instead of the built in Windows Application, such as Notepad.exe
Want to go back to the built in application? simply delete the "Debugger" string-value.
Why is this better than replacing the executable itself?
 1. You keep the original file, so you can always go back to it
 2. You don't have to worry about Windows Protection
 3. You don't have to reboot


y M))', or equivalently, '(\x. \y. M)', can be abbreviated as: (\x y. M) Similarly, '(\x (\y (\z M)))' can be abbreviated as: (\x y z. M) ## Lambda terms represent functions ## Let's pause and consider the following fundamental question: what is a function? One popular answer is that a function can be represented by a set of ordered pairs. This set is called the **graph** of the function. If the ordered pair '(a, b)' is a member of the graph of 'f', that means that 'f' maps the argument 'a' to the value 'b'. In symbols, 'f: a' ↦ 'b', or 'f (a) == b'. In order to count as a *function* (rather than as merely a more general *relation*), we require that the graph not contain two (distinct) ordered pairs with the same first element. That is, in order to count as a proper function, each argument must correspond to a unique result. The lambda calculus seems to be wonderfully well-suited for representing functions. In fact, the untyped lambda calculus is Turing Complete (see [[!wikipedia Turing completeness]]): all (recursively computable) functions can be represented by lambda terms. Which, by most people's lights, means that all functions we can "effectively decide" --- that is, always apply in a mechanical way without requiring any ingenuity or insight, and be guaranteed of a correct answer after some finite number of steps --- can be represented by lambda terms. As we'll see, though, it will be fun (that is, not straightforward) unpacking how these things can be so "represented." For some lambda terms, it is easy to see what function they represent: > '(\x x)' represents the identity function: given any argument 'M', this function simply returns 'M': '((\x x) M) ~~> M'. > '(\x (x x))' duplicates its argument (applies it to itself): '((\x (x x)) M) ~~> (M M)' > '(\x (\y (y x)))' reorders its two arguments: '(((\x (\y (y x))) M) N) ~~> (N M)' > '(\x (\y x))' throws away its second argument: '(((\x (\y x)) M) N) ~~> M' and so on. In order to get an intuitive feel for the power of the lambda calculus, note that duplicating, reordering, and deleting elements is all that it takes to simulate the behavior of a general word processing program. That means that if we had a big enough lambda term, it could take a representation of *Emma* as input and produce *Hamlet* as a result. Some of these functions are so useful that we'll give them special names. In particular, we'll call the identity function '(\x x)' **I**, and the function '(\x (\y x))' **K** (for "konstant": K x is a "constant function" that accepts any second argument 'y' and ignores it, always returning 'x'). It is easy to see that distinct lambda expressions can represent the same function, considered as a mapping from input to outputs. Obviously: (\x x) and: (\z z) both represent the same function, the identity function. However, we said [[in the advanced notes|week2_lambda_advanced]] that we would be regarding these expressions as synactically equivalent, so they aren't yet really examples of *distinct* lambda expressions representing a single function. However, all three of these are distinct lambda expressions: (\y x. y x) (\z z) (\x. (\z z) x) (\z z) yet when applied to any argument 'M', all of these will always return 'M'. So they have the same extension. It's also true, though you may not yet be in a position to see, that no other function can differentiate between them when they're supplied as an argument to it. However, these expressions are all syntactically distinct. The first two expressions are (beta-)*convertible*: in particular the first reduces to the second via a single instance of beta reduction. So they can be regarded as proof-theoretically equivalent even though they're not syntactically identical. However, the proof theory we've given so far doesn't permit you to reduce the second expression to the third. So these lambda expressions are non-equivalent. In other words, we have here different (non-equivalent) lambda terms with the same extension. This introduces some tension between the popular way of thinking of functions as represented by (identical to?) their graphs or extensions, and the idea that lambda terms express functions. Well, perhaps the lambda terms are just a finer-grained way of expressing functions than extensions are? As we'll see, though, there are even further sources of tension between the idea of functions-as-extensions and the idea of functions embodied in the lambda calculus. 1. One reason is that that general mathematical conception permits many *uncomputable* functions, but the lambda calculus can't express those. 2. More problematically, lambda terms express "functions" that can *take themselves* as arguments. If we wanted to represent that set-theoretically, and identified functions with their extensions, then we'd have to have some extension that contained (an ordered pair containing) itself as a member. Which we're not allowed to do in mainstream set-theory. But in the lambda calculus this is permitted and common --- and in fact will turn out to be indispensable. Here are some simple examples. We can apply the identity function to itself: (\x x) (\x x) This is a redex that reduces to the identity function (of course). We can apply the **K** function to another argument and itself: > K z K That is: (\x (\y x)) z (\x (\y x)) That reduces to just 'z'. 3. As we'll see in coming weeks, some lambda terms will turn out to be impossible to associate with any extension. This is related to the previous point. In fact it *does* turn out to be possible to represent the Lambda Calculus set-theoretically. But not in the straightforward way that identifies functions with their graphs. For years, it wasn't known whether it would be possible to do this. But then [[!wikipedia Dana Scott]] figured out how to do it in late 1969, that is, he formulated the first "denotational semantics" for this Lambda Calculus. Scott himself had expected that this wouldn't be possible to do. He argued for its unlikelihood in a paper he wrote only a month before the discovery. (You can find an exposition of Scott's semantics in Chapters 15 and 16 of the Hindley & Seldin book we recommended, and an exposition of some simpler models that have since been discovered in Chapter 5 of the Hankin book, and Section 16F of Hindley & Seldin. But realistically, you really ought to wait a while and get more familiar with these systems before you'll be at all ready to engage with those ideas.) We've characterized the rule of beta-reduction as a kind of "proof theory" for the Lambda Calculus. In fact, the usual proof theory is expressed in terms of *convertibility* rather than in terms of reduction; but it's natural to understand reduction as being the conceptually more fundamental notion. And there are some proof theories for this system that are expressed in terms of reduction. To use a linguistic analogy, you can think of what we're calling "proof theory" as a kind of syntactic transformation. The sentences *John saw Mary* and *Mary was seen by John* are not syntactically identical, yet (on some theories) one can be derived from the other. The key element in the analogy is that this kind of syntactic derivation is supposed to preserve meaning, so that the two sentences mean (roughly) the same thing. There's an extension of the proof-theory we've presented so far which does permit a further move of just that sort. It would permit us to also count these functions: (\x. (\z z) x) (\z z) as equivalent. This additional move is called **eta-reduction**. It's crucial to eta-reduction that the outermost variable binding in the abstract we begin with (here, '\x') be of a variable that occurs free exactly once in the body of that abstract, and that that free occurrence be the rightmost outermost constituent. The expression: (\x (\y (y x)) can't be eta-reduced, because the rightmost outermost constituent is not 'x' but '(\y (y x)'. In the extended proof theory/theories we get be permitting eta-reduction/conversion as well as beta-reduction, *all computable functions with the same extension do turn out to be equivalent*, that is, convertible. However, we still shouldn't assume we're working with functions traditionally conceived as just sets of ordered pairs, for the other reasons sketched above. ## The analogy with 'let' ## In our basic functional programming language, we used 'let' expressions to assign values to variables. For instance, let x match 2 in (x, x) evaluates to the ordered pair '(2, 2)'. It may be helpful to think of a redex in the lambda calculus as a particular sort of 'let' construction. ((\x BODY) ARG) is analogous to let


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My Snake Plant Yellowing
If the leaves on your snake plant yellowing and soft, you may be anxious for a cure. You've come to the proper location if that's the case. Overwatering and root illness can cause snake plant leaves to turn yellow and mushy. Underwatering, excessive sunshine, overfertilization, fungal infections, and insect infestation can all produce snake plant yellowing. I'll go over all of the various causes and solutions to the problem in this article.
Sansevieria is also known as mother-in-tongue laws and snake plant. Isn't it an intriguing name? It's possible that you're giving your plant proper care, yet the leaves are becoming soft and yellow. Some of the possible causes are:
When you overwater your snake plant, you're essentially laying the groundwork for its demise. Yes, it is that hazardous. If your plants begin to turn yellow, you are not doing something correctly! It's time to get serious about your watering routine and save the snake plant as quickly as possible. It's critical that you understand what's causing the leaves to become yellow. The leaves should be in good shape. If you notice a change in the color of your leaves, overwatering may be the first thing that comes to mind. The plant's healthy leaves would be dark green in hue.
There's no such thing as too much or too little! There will be a suitable habitat for fungal illnesses if there is any stagnant water. We certainly don't want it to happen. The snake plants should be watered every 2 to 6 weeks. You can also examine if the soil appears to be dry. You must look after the plant based on its need for water.
Lack Of Light
It's possible that you're exposing your plant to far too much light! Yes, you read that correctly. It produces sunburn in the same way that sitting out in the sun for too long does. It can happen to your snake plant if you leave it outside or in a spot where the sun shines brightly. You might be startled to learn that sunlight shining through your window can harm your snake plant yellowing.
Because the window glass can occasionally magnify the sunray, causing your snake plant to lose more water. As a result, the snake plant yellowing or brown at the tips. Snake plants are simple to maintain. People usually like plants like this for this reason. However, this does not negate the importance of the plant's primary factors. You don't want your plants to be overexposed to the sun. If you keep the plants in indirect sunlight, this is a good idea. You must offer appropriate solar exposure. You'll have to put in some effort to find the appropriate position for your plants if you want to provide indirect sunlight!
It's possible that you're too preoccupied with life! It's also likely that you've heard that if you don't water your snake plant, it will live for a long period. Or perhaps you were on vacation. In any case, insufficient underwatering will manifest some of the same symptoms as overwatering. Because the root system can't get enough water and nutrients if it's underwatered, it can't perform its physiological functions effectively. The nutrients in the soil are still in a soluble state.
You might not be sure if you're underwatering, just like you're not sure if you're overwatering! In fact, if you've heard that overwatering might harm a plant, it's possible that you're not watering it at all. In the winter, make sure you're watering less. It's critical to understand when and how much water your snake plant requires. Now that you've received a plant, it's up to you to take proper care of it. When your plant asks for water, pay heed to it. The outcome would be visible in the hue of the leaves. Are you sure you know what to do next?
Just avoid those things above, it will help you to save your snake plant!


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Ask MAKE is a monthly column where we answer your questions. Send your vexing conundrums on any aspect of making to _EMAIL_. If we don't have the answer, we'll scare up somebody who does.
Non-archival paper that has yellowed over time.
In the post November is Paper Month, Susan asks:
What makes paper archival … or how long will it last?
Paper in it's normal state is naturally acidic, leading to eventual degradation. However, most paper made today is acid-free due to a couple of factors. The filler used in paper used to be China clay, whereas now it's chalk, which naturally has a high pH, making the paper pH neutral. It's also often treated with magnesium or calcium carbonate, giving the paper an alkaline surplus. This protects the paper from further acidification, such as from sulfur dioxide that occurs naturally in the air.
Acid-free paper has a projected lifespan of 500 to 1000 years, depending on quality. As grades of paper increase to "conservation grade", the standards become stricter. Lignin levels are kept below 1% in archival paper (lignin causes paper to become yellow and brittle over time).
True archival grade paper is made from a different material altogether — cotton rag. Used in documents of exceptional legal or historic value, cotton is significantly more durable over time at a neutral pH when compared to paper made from wood pulp.
I hope this answers your question, and all are welcome to contribute to the comments with additional information.


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This term refers to the manner in which the possible vertical range of human hearing is characterised through the occupancy and evolution of the frequency content of sound.
The concept is key to Spectromorphological theory, and the composer and writer Denis Smalley introduces extremely detailed descriptive termninology in "Spectromorphology: Explaining Sound-shapes". Organised Sound Vol. 2, No. 2. Cambridge: Cambridge University Press, 1997.
It should be noted that it is difficult to separate this concept from the perception of pitch, harmonicity, timbre, sound quality and motion.
See also:Composed Space, Discourse within Electroacoustic Music, Frequency, Motion, Spectromorphology, Spectrum


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Square foot gardening
From Wikipedia, the free encyclopedia
Square Foot Gardening is the practice of planning small but intensively planted gardens. The phrase "square foot gardening" was popularized by Mel Bartholomew in a 1981 Rodale Press book and subsequent PBS television series. A full-length companion DVD, Square Foot Gardening (2010), was recently released in collaboration with Patti Moreno the Garden Girl. The practice combines concepts from other organic gardening methods, including a strong focus on compost, closely planted raised beds and biointensive attention to a small, clearly defined area. Proponents claim that the method is particularly well-suited for areas with poor soil, beginning gardeners or as adaptive recreation for those with disabilities.
The original square-foot-gardening method used an open-bottomed box to contain a finite amount of soil, which was divided with a grid into sections. To encourage variety of different crops over time, each square would be planted with a different kind of plant, the number of plants per square depending on an individual plant's size. A single tomato plant might take a full square, as might herbs such as oregano, basil or mint, while most strawberry plants could be planted four per square, with up to sixteen radishes per square. Tall or climbing plants such as maize or pole beans might be planted in a northern row (south in the southern hemisphere) so as not to shade other plants, and supported with lattice or netting.
The logic behind using smaller beds is that they are easily adapted, and the gardener can easily reach the entire area, without stepping on and compacting the soil. In the second edition, Bartholomew suggests using a "weed barrier" beneath the box, and filling it completely with "Mel's mix," a combination by volume of one third of decayed Sphagnum "peat moss", one-third expanded vermiculite and one-third blended compost. For accessibility, raised boxes may have bottoms to sit like tables at a convenient height, with approximately 6″ (15cm) of manufactured soil per square foot.
In this method, the garden space is divided into beds that are easily accessed from every side. A 4′ x 4′, 16 sq ft (1.5 m2) or 120 cm x 120 cm, 1.4 m2 garden is recommended for the first garden, and a path wide enough to comfortably work from should be made on each side of the bed, if possible, or if the bed must be accessed by reaching across it, a narrower one should be used so that no discomfort results from tending the garden. Each of the beds is divided into approximately one square foot units and marked out with sticks, twine, or sturdy slats to ensure that the square foot units remain visible as the garden matures.
Different seeds are planted in each square, to ensure a rational amount of each type of crop is grown, and to conserve seeds instead of overplanting, crowding and thinning plants. Common spacing is one plant per square for larger plants (broccoli, basil, etc.), four plants per square for medium large plants like lettuce, nine plants per square for medium-small plants like spinach, and sixteen per square for small plants such as onions and carrots. Plants that normally take up yards of space as runners, such as squash or cucumbers, are grown vertically on sturdy frames that are hung with netting or string to support the developing crops. Ones that grow deep underground, such as potatoes or carrots, are grown in a square foot section that has foot tall sides and a planting surface above the ground, so that a foot or more of framed soil depth is provided above the garden surface rather than below it.
The beds are weeded and watered from the pathways, so the garden soil is never stepped on or compacted. Because a new soil mixture is used to create the garden, and a few handfuls of compost are added with each harvest to maintain soil fertility over time, the state of the site's underlying soil is irrelevant. This gardening method has been employed successfully in every region, including in deserts, on high arid mountain plateaus, in cramped urban locations, and in areas with polluted or high salinity soils. It is equally useful for growing flowers, vegetables, herbs and some fruits in containers, raised beds, on tabletops or at ground level, in only 4 to 6 inches (150 mm) of soil. A few seeds per square foot, the ability to make compost, to water by hand, and to set up the initial garden in a sunny position or where a container, table or platform garden may be moved on wheels to receive light is all that is needed to set up a square foot garden.
Benefits of Square Foot Gardening
Much less work. Conventional gardening requires heavy tools to loosen the soil, whereas in this method, the soil is never compacted and it remains loose and loamy. Weeding takes only seconds to minutes, due to the light soil, raised beds, and easily accessed plants. Harvests per foot of garden are increased due to the rich soil mixture, well-spaced plants, and lack of weeds produced when following Mel Bartholomew's method.
Water Savings. The soil mixture that is advised has water-holding capacities, so that the garden needs water less frequently, and in much smaller quantities than when using other gardening methods. Water is also spared by hand-watering directly at the plant roots, so that there is very little waste and tender young plants and seedlings are preserved
Very little weeding. One benefit of this close planting is that the vegetables form a living mulch, and shade out many weed seeds before they have a chance to germinate.
Pesticide / Herbicide Free. Natural insect repellent methods like companion planting (i.e. planting marigolds or other naturally pest-repelling plants) become very efficient in a close space and thus, pesticides are not necessary. The large variety of crops in a small space also prevents plant diseases from spreading easily
Accessibility. A plywood bottom can be attached to the bottom of a box, which can then be placed on a tabletop or raised platform for those who wish to garden without bending or squatting, or to make gardening easy for wheelchair, cane or walker users.
Covers and Cages. Because all beds are small (4'x4′ or smaller), making covers or cages to protect plants from pests, cold, or sun is more practical than with larger gardens.
Andrew Vowles; Vern McGrath, Susan Todd (June/July 2002). "The Plot Thickens: Square-foot gardening offers bigger yields in less space". Techniques (Canadian Gardening (CG Online)): p. 96. Retrieved 2007-08-06. Note: Publication Information found in 2002 Article Index and is not available on-line with the article
Mel Bartholomew Interview – An Interview With the Creator of Square Foot Gardening
Official Site of Square Foot Gardening website of creator Mel Bartholomew, includes info on how to get started, tips and FAQs


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Carbon detonation is a characteristic event of Type 1a Supernova (EDIT: where an accreting white dwarf near the Chandrashankar limit of 1.4 solar masses explodes), an extremely important standard candle for cosmology. An area of active research is designing computer simulations to model supernova spectra and light curves and fit these to ones obtained observationally to better understand the effect of trace elements and characteristics of the explosion (asymmetry, companion star properties, etc) in order to provide better distance estimates to get more accurate constraints on cosmological parameters (Hubble constant, Dark Energy equation of state, etc).
But it would be very interesting (and extremely cool) if there was a way of generating carbon detonations in a laboratory situation in order to study these effects. What sort of temperature/pressure range is necessary to generate a carbon detonation? Would it be in the range of experimental apparati? Or, on the extreme sides of things, a large thermonuclear device?


What you can say when selling organic food
Since the beginning of 2013 the organic market has begun to show signs of recovery. We believe this is a crucial moment for everyone in the organic movement to come together with a clear call to consumers - organic is food you can trust, better for the environment and animal welfare. We believe that there is strong scientific evidence to back up most of the benefits that those of us involved in organic farming and food know it delivers.
For decades we have worked tirelessly to help prove the key tangible consumer benefits of organic food and farming and have regularly published guidance on approved statements. We have created a detailed PDF guide of 'what you can say when marketing organic' which is available free of charge to all Soil Association licencees.
Advertising Standards Authority and Copy Advice
In the UK, marketing statements are overseen by a voluntary system, funded by the advertising and related industries, and run by the Advertising Standards Authority (ASA). Businesses wanting to know if statements they make about their products will be found to be inaccurate by the ASA if a complaint is made about what they say, can check in advance with the Committee of Advertising Practice - called Copy Advice.
Copy Advice say they are 'responsible for writing and maintaining the UK Advertising Codes and providing authoritative advice on the rules'. They are funded 'by an arm's length levy on advertising space and a small amount of income raised from charging for some training seminars and premium advice services'.
The Advertising Codes are administered by the Advertising Standards Authority. Copy Advice are linked to but say they are independent of the ASA, and always take pains to stress that if they advise that a statement is acceptable, it still may be found to be unacceptable by the ASA. Nevertheless, Copy Advice's view carries some weight with the ASA, and certainly provides a useful guide to advertisers.
You can't say everything that is true!
The rules governing what you can say to sell a product, as administered by the ASA, do not simply rely on a statement being true. For example, you are
not allowed to say something that the ASA might feel 'denigrates' other products. Recently, the European Union introduced new, very strict, rules about any statements implying that a product has nutritional benefits or will make people healthier - such statements are now extremely difficult to make, and the new rules are still very unclear, and will remain so until they have been subject to rulings by the European Court.
The ultimate outcome is likely to reflect well on the organic movement, because whilst the number of nutritional/health claims overall will be reduced, some of the spurious claims made by elements of the food industry will be banned for good.
Using our guide
 1. Once you have decided to use a statement, we strongly recommend you then check your actual advertisement with Copy Advice. The context in which the statement is used, and any associated imagery, can alter the meaning of the words. Copy Advice can be reached via their website and proposed statements can be submitted via the website for free advice.
 Copy Advice always undertake to respond within 24 hours, and in our experience their staff are generally helpful, and willing to explain the basis of their advice. However, remember that Copy Advice will always qualify their opinion by stressing that it does not bind the ASA itself.
 2. You need to hold any evidence that might be required, to substantiate the statements you make, when you make them. We have a fully referenced version for the statements some referring back to our own organic standards, and where appropriate to the relevant scientific research.
The statements are available to Soil Association licensees on request. Please contact Katie Stinchcombe at _EMAIL_


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July 23, 2010
A happy number is defined by the following process. Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers, while those that do not end in 1 are unhappy numbers (or sad numbers).
For example, 7 is a happy number, as 72=49, 42+92=16+81=97, 92+72=81+49=130, 12+32+02=1+9+0=10, and 12+02=1+0=1. But 17 is not a happy number, as 12+72=1+49=50, 52+02=25+0=25, 22+52=4+25=29, 22+92=4+81=85, 82+52=64+25=89, 82+92=64+81=145, 12+42+52=1+16+25=42, 42+22=16+4=20, 22+02=4+0=4, 42=16, 12+62=1+36=37, 32+72=9+49=58, and 52+82=25+64=89, which forms a loop.
Your task is to write a function to identify the happy numbers less than a given limit; you should work at the level of a programming interview, taking no more than about fifteen minutes, and giving a short explanation of your work to the interviewer. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.
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Joanna has certified training in conducting custody and access assessments.
What is a Custody and Access Assessment?
A custody and access assessment provides information to the court on a parenting arrangement for the children, when parents are not able to agree on parenting time and decision-making. Custody and access assessments are typically court ordered under Section 30 of the Children's Law Reform Act or on consent of both parties. The purpose of the assessment is to determine the best interest of the child.
The process involves extensive interviews with the parents, the children, important family members and community contacts such as the child's school, medical doctors and therapists. Thorough observations of each parent and child will also be included in the assessment to determine the quality of the relationship between the parent and child. At the end of the process, a disclosure meeting is held where the assessor meets with the parents and/or counsel to communicate the findings and recommendations. This usually comes in the form of a parenting plan to help the families resolve their dispute. The family may choose to settle at this point. A detailed and comprehensive report can be provided to assist the court in determining the custody and access of the child(ren).


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همکاری نیمکره درونی برای تشخیص چهره اما نه برای حالات عاطفی چهره
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|37596||2003||8 صفحه PDF||سفارش دهید||محاسبه نشده|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Neuropsychologia, Volume 41, Issue 4, 2003, Pages 407–414
Abstract Interhemispheric cooperation can be indicated by enhanced performance when stimuli are presented to both visual fields relative to one visual field alone. This "bilateral gain" is seen for words but not pseudowords in lexical decision tasks, and has been attributed to the operation of interhemispheric cell assemblies that exist only for meaningful words with acquired cortical representations. Recently, a bilateral gain has been reported for famous but not unfamiliar faces in a face recognition task [Neuropsychologia 40 (2002) 1841]. In Experiment 1 of the present paper, participants performed familiarity decisions for faces that were presented to the left (LVF), the right (RVF), or to both visual fields (BVF). An advantage for BVF relative to both LVF and RVF stimuli was seen in reaction times (RTs) to famous faces, but this bilateral advantage was absent for unfamiliar faces. In Experiment 2, participants classified the expression (happy or neutral) of unfamiliar faces. No bilateral advantage was seen for expressions, although a right hemisphere superiority was seen in terms of higher accuracy for LVF and BVF trials relative to the RVF. Recognition of famous faces (but not of facial expressions) require access to acquired memory representations that may be instantiated via cortical cell assemblies, and it is suggested that interhemispheric cooperation depends on these acquired cortical representations
. Introduction The cerebral hemispheres develop specialisations for a number of tasks and. For instance, language processing has been attributed to the left hemisphere (LH), whereas face processing has been related to right hemisphere (RH) function. However, whereas traditional models tended to stress an absolute "dominance" of the LH or RH for a particular task, more recent work has emphasized that tasks should be considered as composed of separable task components, and that relative rather than absolute specialisation exists for a number of tasks. This leads to the important question as to if and how the two hemispheres collaborate in cognitive processing. One possibility to test hemispheric interaction is to present stimuli tachistoscopically either unilaterally to the left (LVF) or right visual fields (RVF), or to present the same stimuli simultaneously to both fields (BVF). The anatomy of primary visual pathways provides that LVF and RVF stimuli project directly to the RH and LH, respectively. Thus, unilateral stimuli initially project to only one hemisphere, but bilateral stimuli project to both hemispheres simultaneously. Many studies demonstrated better processing in the bilateral condition compared to the best unilateral condition. This effect (also called bilateral advantage or bilateral gain) has been found for words,, and and famous faces. In contrast, it has never been seen for meaningless pseudowords or unfamiliar faces. A bilateral advantage has been first observed in lexical decision, where participants discriminate between words and pronounceable pseudowords in a series of letterstrings by speeded keypress responses. A consistent finding in this task is that words but not pseudowords lead to a robust bilateral advantage,, and. Moreover, in a split-brain patient with complete commisurotomy in whom any (cortically mediated) interaction between the hemispheres was unlikely, the bilateral advantage was absent. These findings indicate four major theoretically important processing characteristics of the two hemispheres: First, redundant information facilitates processing, but only for previously learned stimuli (such as words or famous faces). Second, facilitation also occurs when information is divided across hemispheres, supporting the notion of hemispheric cooperation rather than independence. Third, hemispheric cooperation after bilateral presentation of a stimulus reflects cortical representation of that stimulus over both hemispheres. Fourth, the lack of a bilateral advantage in split-brain patients suggests that this bihemispheric representation includes excitatory connections via the corpus callosum, and. Several models have been proposed to explain the bilateral advantage. First, a bilateral advantage might reflect a simple "horse race" between two independently operating hemispheres, in which the hemisphere specialised for a certain operation "wins the race". Accordingly, this would cause a pattern in which performance for bilateral trials is always superior to unilateral trials for all kinds of stimuli (for discussion ). Thus, a horse race model fails to account for a bilateral advantage seen for some stimuli but not for others. A neurocognitive model can better account for this differential bilateral advantage. Based on Hebb's theory, it has been held that words are cortically represented by strongly connected cell assemblies (CAs). CAs may be distributed across both hemispheres, in line with findings of relative rather than absolute specialisation of the LH for language processing and. If a word is represented by a CA that is distributed across both hemispheres, there will be strong excitatory connections across the corpus callosum within this CA. If stimulated with only one copy via input through one hemisphere, the CA activation is relatively slow and less efficient than when stimulated with two copies via input through both hemispheres. This would explain a bilateral advantage for meaningful words. At the same time, no bilateral advantage should be seen for novel pseudowords which are relatively meaningless, and which are not thought to be represented by cortical CAs. Although the bilateral gain has been mainly investigated in language studies, it should be possible to extend this account to the processing of other stimuli. Faces seem a good candidate stimulus, because although many aspects of face perception seem to be lateralized to the RH,, and, both hemispheres contribute to it, and. We have recently demonstrated a bilateral advantage in a face recognition task. Participants performed familiarity judgements for famous and unfamiliar faces flashed to either the RVF, LVF, or BVF. A significant bilateral advantage was obtained for famous but not for unfamiliar faces. These results extend earlier findings beyond the verbal domain, and suggest that interhemispheric cooperation may depend on the recognition of stimuli for which a cortical representation has been acquired. Alternatively, interhemispheric cooperation might depend on the recognition of stimuli which are particularly meaningful or informative (e.g. "target" stimuli, such as words in lexical decision, or famous faces in face familiarity decision). The aim of the present study was to extend our initial findings on interhemispheric cooperation in face processing, by comparing two different face processing tasks (face recognition versus recognition of facial expressions). In Experiment 1, participants performed familiarity judgements for famous and unfamiliar faces presented to either the RVF, LVF, or BVF. In Experiment 2, we presented unfamiliar faces with different expressions (either happy or neutral), and the task was to recognise the expression displayed.1 The recognition of facial expressions, just like facial identification, is thought to rely more on the RH than the LH. Also, happy expressions can be regarded as informative target stimuli in this task, just like famous faces can be regarded as informative target stimuli in a familiarity task. However, we reasoned that the recognition of expressions does not require the contact with a learned cortical representation in the same way as recognition of face identity does. Identification of a face clearly requires the contact with an acquired memory representation, and one that is likely stored cortically, presumably in inferior temporal areas and. It is also more difficult to store and identify faces from other-race faces. In contrast, the ability to recognise facial expression is thought to be innate and universal across cultural and racial borders. Humans easily recognise expressions of someone they have never seen before, suggesting that recognition of expression does not require access to an acquired cortical representation. Instead, recognition of facial expression may be mediated by phylogenetically older limbic mechanisms, in particular the amygdala or basal ganglia. These considerations led us to propose the following hypotheses. If interhemispheric cooperation depends on whether recognition involves an acquired cortical representation, we would predict a bilateral gain for famous but not unfamiliar faces in the familiarity task. In addition, we would not expect a bilateral advantage for faces in an expression task. In contrast, if interhemispheric cooperation depends on whether or not the stimulus is an informative target stimulus for a particular task, one would expect a bilateral gain for affective but not for neutral expressions in an expression task.
نتیجه گیری انگلیسی


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Client: Department of Premier & Cabinet Victoria
– Multicultural Affairs and Social Cohesion Division
Context: Victoria is growing and becoming more diverse. Jobseekers from a range of backgrounds face barriers in finding work. Global research tells us that diversity is good for the workforce, the economy, and the community. Culturally diverse teams are more creative and solve complex tasks more efficiently than culturally homogenous teams. So why is there still resistance?
Recruit Smarter was created to address this issue. It is a multi-sector strategic initiative of the Victorian Government in conjunction with Universtiy of Melbourne, the Centre for Ethical Leadership and VicHealth. Its aim was to develop inclusive recruitment practices and address unconscious bias in recruitment.
It was run over two years around three priorities: trialling new approaches, designing best practice and sharing knowledge.
Crealo produced a series of small, simple infographics used in a 2017 social media campaign. 2018 saw the culmination of the research, and we were engaged again to produce a range of visual materials aimed at audiences from the general public to employers, as well as government officials.
We created three main pieces of collateral:
- A four page summary infographic, painting the context of the initiative and the findings from the two years of research. Findings centred around the trial of new approaches like CV de-identification, unconscious bias training, collaboratively developed best practice guidelines and knowledge sharing.
- Design of the Key Findings document, using a mix of graphics and photography to present the ideas and statistics in interesting ways
- The complete 70 page research report.
Various isolated infographic illustrations about Victoria's population:


Classi-Compare of Raster Satellite Images – Before and After
August 13, 2013
For my research on the effect of power outages on fertility , we study a period of extensive power rationing that lasted for almost a whole year and affected most of Latin America, but in particular, it affected Colombia. The key difficult was to determine which areas were exposed to the power-outage and the extent to which this was the case. This is not straightforward, since there does not exist householdor even municipality level consumption data.
But here is how R and Satellite Data can help. In particular, we study the night light series obtained from the Defense Meterological Sattelite Program, which has been discussed by Jeffrey before.
We simply look for abnormal variation in municipality level light-emitting intensity from 1992 to 1993.
Here is some code that generates some Raster-Maps using the package rasterVis, and uses jQuery to generate a fancy before and after comparison to highlight the year-on-year changes in light intensity of 1992 compared to 1993.
###load the raster images
f151 = raster(tif)
f152 = raster(tif)
##crop a smaller window to plot
e = extent(-78,-72,2,8)
_TAG_ = extent(-80,-78,-4.6,-2)
rn= crop(f151, e)
rn2= crop(f152, e)
### do a logarithmic transformation to highlight places that receive not much, but some light.
p <- levelplot(rn, layers=1, margin=FALSE,col.regions = gray(0:100/100))
p + layer(sp.polygons(COLPOB, lwd=.25, linetype=2, col='darkgray'))
p <- levelplot(rn2, layers=1, margin=FALSE,col.regions = gray(0:100/100))
Now with this together, you can create a fancy slider as I have seen on KFOR -- comparing satellite pictures of towns before and after a tornado went through them.
The code is essentially just borrowed from that TV station and it loads the javascript from their server; it is essentially just a clever use of jQuery and is maybe something that could or is already implemented in an R reporting package? Do you know of such a function?
Anyways, all you need is a slider.html page that contains the code referring to the two picture sources; the code is simple:

 .sample1 {width:725px; height:725px;}.sample2 {width:725px; height:725px;}.sample3 {width:725px; height:725px;}

This is how it looks -- I know the stuff is not perfectly aligned, partly because when cropping the picture I made a mistake and could not be bothered with fixing it.
Have fun!
Comments are closed.


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The summit is designed to provide information to the entire community to raise the level of awareness of education issues. The theme of this year's summit is "Preparing Our Children for Their Future."
Our students will be competing for jobs with others from around the world. Employers are now looking for 21st century skills such as creativity, problem solving, communication, innovation, and critical thinking. Kentucky has adopted new curriculum standards to address the new skills. The keynote by Gene Wilhoit will address the new standards and how these standards will prepare our students and the community for the future. I have heard Mr. Wilhoit speak a couple of times in the last year; he will inspire you about the future of education.
The Kentucky Department of Education must change to meet the demands of the future. Therefore, KDE Associate Commissioner for the Office of Next Generation Learners, Felicia Cumings Smith, will be discussing the Next Generation Learners concept. Mrs. Smith is overseeing much of the work related to the implementation of the new standards.
The process of preparing our children for their future must start with the early years. It is in those years that a child's brain is developing and habits are being formed. Therefore, there will be a session on the importance of laying a strong foundation to help students learn at high levels. There will also be a session explaining on how schools can help each and every student learn.
Active parent involvement in education raises student achievement. Many times parents simply do not know the opportunities for involvement. As a parent you will be able to attend a breakout session where a local parent will share how he became involved in Trigg County Public Schools.
Even if you are not an educator or a parent, education is important to the local community as a whole. Ultimately, the quality of education our students receive affects the wellbeing of the community and the life we all enjoy. A strong education system will help to recruit new business and industry which in turn creates new jobs. As a community member, we need you to be involved to help make a difference in our schools, no matter your role. While the entire summit will help raise your awareness, local business members will share how they have become strategic partners with the schools.
The Education Summit will be held on Saturday, February 5, 2011 from 8:00 a.m. until 12:00 p.m. at Hopkinsville Community College, 720 North Drive, Hopkinsville, KY 42240
We want to see you at this year's Regional Education Summit. It is a tremendous opportunity to learn more about public education in our area and how you can be a more active participant in improving education for our kids. You can register online at _URL_


Turbine efficiency equation
How do you calculate turbine efficiency?
Calculate steam turbine efficiency by dividing the theoretical pounds per hour of steam by the steam actually consumed. This is 44,855.58 pounds (theoretical) / 52,462 pounds actual = 0.855 or 85.5 percent operating efficiency.
What is the efficiency of turbine?
How do you calculate isentropic efficiency of a turbine?
Hence, the definition of isentropic efficiency of turbine is the ratio of the actual work output of the turbine to the work output of the turbine if the turbine undergoes an isentropic process between the same inlet and exit pressures. Compressors and pumps, when undergo a steady-flow process, consume power.
Why is steam turbine efficiency so low?
A decrease of the steam pressure pt in the condenser causes a decrease of the steam condensation temperature and consequently increases the temperature difference in the cycle. The efficiency of steam-turbine units increases when regenerative extraction of steam from the turbine is used.
Which turbine has highest efficiency?
Large Francis turbines are individually designed for each site to operate with the given water supply and water head at the highest possible efficiency, typically over 90%. In contrast to the Pelton turbine, the Francis turbine operates at its best completely filled with water at all times.
What are the formula for power?
The standard metric unit of power is the Watt. As is implied by the equation for power, a unit of power is equivalent to a unit of work divided by a unit of time. Thus, a Watt is equivalent to a Joule/second.
Why is gas turbine efficiency so low?
The decrease in the thermal efficiency is due to the decrease in the compressor efficiency and pressure ratio. Trends in gas turbine power and thermal efficiency due to compressor fouling when operating at low power.
Are turbine engines efficient?
Latest generation gas turbine engines have achieved an efficiency of 46% in simple cycle and 61% when used in combined cycle.
What is turbine and how it works?
What is an ideal turbine?
The ideal (theoretical) steam turbine is considered to be an isentropic process, or constant entropy process, in which the entropy of the steam entering the turbine is equal to the entropy of the steam leaving the turbine, with isentropic efficiencies ranging from 20–90%.
Why is a turbine adiabatic?
Two general classes of turbines are steam and gas turbines depending on the working substance used. Usually, changes in potential energy are negligible, as is the inlet kinetic energy. Normally, the process in the turbine is adiabatic and the work output reduces to decrease in enthalpy from the inlet to exit states.
What is compressor efficiency?
Compression efficiency is usually defined as the adiabatic efficiency also known as isentropic efficiency and so is the ratio of the adiabatic power to the PV card indicated power: EFF = AP / IP × 100 %
How do you increase steam turbine efficiency?
Tips to improve steam plant efficiencyStep 1: Do a Steam Trap Survey. First, a steam trap survey can easily identify leaking or faulty traps and provide significant potential savings. Step 2: Understand the Value of Condensate. Step 3: Insulate your Steam System. Step 4: Look for Steam Leaks. Step 5: Start Steam Metering.
You might be interested: Harmonic wave equation
How efficient is a water turbine?
Efficiency. Large modern water turbines operate at mechanical efficiencies greater than 90%.
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Equation for decibels
Convert to an exponential equation
How do you convert a logarithmic equation to exponential form? How To: Given an equation in logarithmic form logb(x)=y l o g b ( x ) = y, convert it to exponential form. Examine the equation y=logbx y = l o g b x and identify b, y, and x. Rewrite logbx=y l o […]


Light-Camera-Glitter Simulation
In one of my last blog posts, I discussed the preliminary results of trying to optimize for both the camera & light locations simultaneously. I have been working on a simulation of our geometry to try and understand this better. To recap, it seems that there is a slight ambiguity in the position of the light and camera, in that they can move slightly along two rays and still give a lower error. One thought is that it is an error in how we are modeling the light and the gaussian receptive field of the glitter. Another thought is that it may have to do with the fact that our light is not a point light source, but rather a small square; so we don't quite know what part of the light a glitter piece sees. More likely is that it some combination of these two issues.
In this blog post I want to highlight where I am in the simulation, and what it shows so far. I simulate 10,000 pieces of glitter that lay on a place, each with a surface normal corresponding to some random screen location. 500 of them (chosen at random), however, have surface normals that allow the glitter to see the simulated point light and the simulated camera. For those that 'see' the light, I give them intensity values of 1, and give intensity values of 0 for all of the rest.
I then compute the predicted intensities for each glitter pieces using a few different gaussian values for the light and the glitter receptive field. Below, the non-yellow rays are the pieces of glitter that have actual intensity values of 0, but predicted intensity values between 0.1 and 1.
The above images are made using a light gaussian size of 5 and a glitter receptive field of 40. As the predicted intensity gets higher, the rays getting lighter (and farther away from the camera), which is exactly what we would expect to happen in this system.
Next, I am adding in the actual 'optimization' part of the simulation. As a first pass, I will just optimize for everything (including light and camera) and see what happens. In doing that, I hope to understand what parameters to tune, and I can start fiddling with the way in which I am predicting intensities and how I am modeling receptive fields.
Exploring 3D Light Location as an Optimization Parameter
The second thing I am spending time this week working through is adding the light location as a parameter that can be optimized over in the calibration. This involved adding a new flag indicating if we treat the light location as known or not, and if we treat it as unknown, then we optimize for the light location in steps 1 & 3 of the 3-step optimization.
In order to make this task as 'easy' as possible, I am only optimizing for translation, rotation, focal, gaussian and light location (everything I did for WACV + light location), and I have not changed the RANSAC protocol to include the fact that the light is unknown. I also initialized the light location to be the correct light location. This blog post will focus on the results of this calibration run.
The main thing I notice is that the camera and light seem to be able to both move slightly, as if they were each attached to a string, one on each end, that was on a pulley in the middle.
The upper image shows a birds-eye view of the setup, with the monitor on the left and the glitter on the right. The bottom image shows the view of the setup looking at it from the side of the table (looking towards the drones). The dotted-line frustum is the GT camera location and zoom, while the red-outlined frustum is the optimized camera location and zoom. The blue circle is the GT location of the center of the square of light displayed on the monitor, and the magenta circle is the optimized location of the center of the light.
The main thing I notice here is that the optimized camera is millimeters closer to the glitter, along the axis in line with the lens. Meanwhile, the optimized light is millimeters farther from the glitter, almost straight back (and slightly lower).
Here we can maybe see why this is the case (again from a birds-eye view of the setup). We are treating the light location as a point light source with some gaussian (which may not be the most accurate representation of our light). So, while all of the rays may fall within some small 'square of light' on the monitor, they actually more-or-less intersect close to a point a little further behind, and in this case even below, the point on the monitor where the light actually was.
This leads me to believe that I need to take a look at the method by which I am using the gaussian representation of our light, and think about how we can represent our light more accurately. Or maybe we need an even smaller light source (more like an actual point light). Something to think about for the re-implementation of the setup!
Correcting for Checkerboard Thickness
One of the potential (definite) sources of error that we found in our exploration of camera calibration over the last several months is the thickness of the checkerboard – the checkerboard does not lie in the same plane as the glitter sheet, even when we place the checkerboard directly on the glitter. This is a factor that I had not considered at all, and it was brought to my attention recently. This is something that we will address in the next iteration of the calibration setup, but for now I want to try to correct for this in the measurements I have. In order to compute the camera location in 3D world coordinates, we implement the following process…
 1. Take ~25 pictures of the checkerboard in various/random orientations, 1 of which is a picture of the checkerboard sitting straight and flush against the glitter:
2. Find 3 orthogonal points on the checkerboard in order to establish a coordinate system for the checkerboard, shown in green/red (red just to help me know which is the upper left):
3. Map these 3 points into our glitter coordinate system using a homography:
4. Compute the 3D world coordinates of these 3 points – now these 3D coordinates are in the plane of the glitter, which is ~3mm behind the plane of the checkerboard. Herein lies the problem.
Gut Check: We know the squares are 24.5mmx24.5mm. When I compute the 3D locations of the 3 points shown above, I get the x-distance from upper left to upper right to be 98.8 (that actual distance on the checkerboard is 98). I get the y distance from upper left to lower left to be 74.0653 (that actual distance on the checkerboard is 73.5). I also compute the dot product between the two 'axis' vectors formed by the 3 points, and get -0.0021 (so they are almost orthogonal).
The MATLAB Camera Calibration Toolbox gives me a location of the camera relative to the checkerboard. I then do a change of coordinate system in order to get this camera location in world coordinates. So, if the checkerboard is being treated as being in the plane of the glitter sheet (which it is), then my relative location of the camera will be computed to be ~3mm closer to the glitter sheet than it actually is.
I think I can just subtract ~3mm from the x coordinate of the 3D location of the checkerboard points, and then compute the camera location in 3D world coordinates as I was before. The y-coordinate and the z-coordinate don't change since the checkerboard is flush with the glitter sheet (and the glitter sheet lies flat in the y-z plane). So then this effectively gives a camera location that is ~3mm behind where the checkerboard gives as the location.
My understanding then is that I will need to re-run characterization using this new camera location, and then use this new characterized data to run calibration. This seems too simple — I'll end my post here and leave it open to comments about my reasoning.
Full Camera Calibration
 - Translation: Ray intersection of consistent glitter
 - Rotation: Looking along the world coordinate system x-axis ([\frac{\pi}{2}, \frac{-\pi}{2}, \frac{\pi}{2}])
 - Focals: [10000, 10000] — this is the middle of the range of the lens we are using
 - Image Center: The actual center of the calibration test image
 - Distortion: [0, 0] — different idea is to do a quick & dirty grid search over possible distortion values and choose the best as the intialization
 - Skew: Trying various fixed values…the next portion of this post focuses on this
Below is a table with results for the calibration run using a different fixed values for the skew. All other initializations are as described above.
As you can see, the values for translation, rotation, focal and gaussian (all of the parameters from the original calibration) are relatively consistent for each experiment. However, there is quite a bit of variation in the skew and the distortion parameters.
During the second and last steps of the optimization, I am computing the 'CALTag Error' in which I compute the reprojected image coordinates of the caltags and the consistent glitter, undistort them, and then compare these to their actual image coordinates. This is where the distortion parameter gets used. During this same 'CALTag Error' process, I am using the calibration matrix, K=\begin{bmatrix}f1 & s & cx\\0 & f2 & cy\\0 & 0 & 1\end