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1nm * DataAnalysis * nCNC * PSM * YourResearch
New data post-analysis tools for A11 nCNC data released
Quite often during a measurement campaign, there is not enough time to really focus on the data of an individual instrument. Sometimes you would for example like to change the settings of the inversion, like the number of size bins or the estimate of diffusion losses in the sampling lines, after the measurement campaign. This is why the Airmodus A11 nCNC system saves both the online inverted data and the raw data.
Airmodus offers free data post-analysis tools that make it possible to invert the A11 nCNC scanning mode data with different settings still after the measurements. As the platform for data analysis, we chose an open source software called Scilab (_URL_ It is a tool that can be used for numerical analysis and data visualization.
Airmodus uses GitHub (_URL_ to distribute the data analysis tools for A11 nCNC data, in order to have fully see-through data analysis—and to have the chance to work with the whole user network on new methods and tools to better use the A11 nCNC data. Every user is free to suggest new functions, methods etc. to the code, and can make their own codes available for other users as well.
The latest version of the scanning data inversion tool has many updates to the data analysis process, including:
- Better utilization of the calibration data
- The fitting is now based on linear interpolation, and thus follows much better the calibration data.
- Better data visualization
- The data bins are visualized for individual size distribution scans. Also, the total number of particles above the largest size bin is plotted.
- New optional data quality check before the inversion is implemented
- This option prevents inversion errors by not inverting unqualified data. Please see the Airmodus GitHub page for more information.
- Improved error handling


Tuareg (Tamasheq, Tamajaq, Tamahaq)
Tuareg is a Berber language or a number of closely-related languages spoken in parts of Mali, Niger, Algeria, Libya and Burkina Faso by the Tuareg people, and by some Kinnin people in Chad. The total number of speakers is about 1.2 million.
Tuareg is traditionally written with the Tifinagh alphabet, which is now mainly used to write magical formulae, writing on palms when silence is required, and for letter-writing. The Arabic alphabet is also used in some areas, and has been since the Middle Ages, and different versions of the Latin alphabet are used in Mali and Niger.
Tuareg alphabets and pronunciation
Tamasheq alphabet
This is the official alphabet for Tamasheq in Mali. It was adopted in 1967 and modified in 1982.
Tamasheq alphabet as used in Mali
Tamajaq alphabet
This is the official alphabet for Tamajaq in Niger and it was adopted in 1999.
Tamajaq alphabet as used in Niger
Sample text in Tamasheq
Mdan ddunt tiwen llullin, ulan s lhəq. Ǧrawən tayətte d man full ed nmərtayən s taññət.
Tamasheq sample text in the Neo-Tifinagh alphabet
Sample text in Tamasheq in the Neo-Tifinagh alphabet
Source: _URL_
Tower of Babel in Tamasheq
Information about Tuareg languages and people
Berber languages
Ancient Berber, Guanche, Kabyle, Tamazight, Tuareg
Other languages written with the Latin alphabet
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USGS Multimedia Gallery
Title: Endangered Hawaiian Hoary Bat
An endangered Hawaiian hoary bat, a species that is sometimes killed by wind turbines. USGS scientists from Hawaii and Colorado are devising a way to directly observe bat occurrence and behavior at wind turbines using a video system composed of high-powered illuminators and near-infrared cameras. This new approach images the full rotor-swept areas of wind turbines for entire nights and long durations, and then uses advanced image-processing software to automatically find flying bats and birds in the copious amounts of recorded footage. This a significant step in developing a feasible method to enhance our understanding of how wind turbines affect bats and nocturnal migratory birds, with the ultimate goal of finding new ways for wind-energy development to continue expanding while reducing the harmful effects of this renewable energy source on wildlife.
Photographer: Frank Bonaccorso, USGS
Usage: This image is public domain/of free use unless otherwise stated. Please refer to the USGS Copyright section for how to credit the photo.
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source: HuggingFaceFW/fineweb-edu


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Link to publisher version (URL)
Over the years, there has been fierce debate about the definition of numeracy and literacy for Academic Language and Learning (ALL) practitioners and at times, we seem to work in parallel universes, but on reflection, we have more in common than is originally supposed. For students enrolled in mathematics courses in higher education, especially those in Education fac-ulties or schools, previous experience of studying mathematics does not al-ways equal competency with, and confidence in dealing with numeracy at tertiary level. McNaught and Hoyne (2011) argue that these concepts are co-dependent. Also, our diverse student population often struggles to achieve confidence and competency with academic language and literacy. This paper discusses our similar approach to teaching and learning where initially con-fidence is generated before challenges are issued and where explanation is privileged over discipline knowledge transference. Through our shared teaching in an ALL-focused program developed at our university, we are able to find common ground and greater understanding of each other's expertise.

source: openbmb/Ultra-FineWeb


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near the base of the tree. Slowly turn the compass until the needle is again pointing in the same direction as the N on the compass.
- Place the fourth stick at the base of the tree so that it is perpendicular to the compass needle and pointing east from the base of the tree. This will be your east stick. If desired, use another stick to scratch out an "E" beside the east stick to help you remember its direction.
Figure 6. This photo shows how to make the east stick perpendicular to the compass needle.
- You will now have four sticks pointing out from the base of the tree in each of the four directions, as shown below.
Figure 7. This photo shows a tree with the four directions marked around its base.
Go to each stick and take a photograph of the base of the tree, using the following instructions:
- Kneel down so that your camera is parallel to the ground as you take the photograph (but it doesn't need to be on the ground).
- Use the stick as a guide for each photograph. As you look through the viewfinder, make sure the stick will be in the bottom center of each photo, as shown below.
- Try to stay the same distance away from the tree for each photograph. You can use the measuring tape to help you stay approximately the same distance away.
- You may want to take a couple of photos just in case your first photo doesn't work out.
- Write down in your lab notebook which stick you photographed first, second, third, and fourth, so that when you take the photos home and print them out, you will know in which direction you were looking.
Figure 8. This photo shows two example photographs taken of a tree from different directions.
- Repeat steps 2–11 for two other trees.
Analyzing Your Photos
- Print out your photos onto graph paper.
- If desired, shade in the moss with one colored pencil and shade in the bark with a different colored pencil to make it easier to distinguish the two on the graph paper.
- Count up the approximate number of squares that are covered by moss. For partial squares, estimate how much of the square is covered by moss, for example, if it looks like one-fourth of the square is covered, add 0.25; if it looks like half of the square is covered, add 0.5; if it looks like three-fourths of the square is covered, add 0.75. For each tree, enter your counts in a data table, like the one below:
Tree 1 Square Counts Data Table
|Direction||Number of moss-covered squares||Total number of tree base squares. (Count up all the squares in the tree base, whether they are covered by moss or just bark.)||Percentage of the tree base covered by moss = (Number of moss-covered squares divided by the total number of tree base squares) x 100|
- Count up the total number of tree base squares (any square that falls within the tree base, whether it is covered by moss or just bark), and enter your count in the data table.
- Calculate the percentage of the tree trunk base that is covered by moss for each direction by dividing the number of moss-covered squares by the total number of tree base squares and multiplying by 100.
- Combine your three data tables into one by entering the last column of each table into a new data table, like the one below.
Percentage of the Tree Bases Covered by Moss Data Table
- For each direction, calculate the average percentage of the trees that were covered by moss and enter your calculations in the data table.
- Make a bar chart showing the four directions on the x-axis and the average percentage of the tree bases that were covered by moss on the y-axis. You can make the bar chart by hand or use a website like Create a Graph to make the graph on the computer and print it.
- In which direction did you observe the most moss growth? In which direction did you observe the least? Do you think moss growth is useful as an indicator of cardinal direction?
If you like this project, you might enjoy exploring these related careers:
- Try using mushroom growth around trees, instead of moss. Be careful not to touch the mushrooms, as they could be poisonous.
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Embark on a mysterious puzzle journey with "LOST" on English Quiz. Test your knowledge of the enigmatic characters and intricate plot twists that captivated audiences worldwide. From the determined Jack to the enigmatic Sawyer, each character adds a layer to the island's compelling narrative. Enhance your vocabulary and problem-solving skills while navigating through the thrilling mysteries, time travel, and unexpected alliances that define this iconic series. Whether you're a devoted fan or a puzzle enthusiast, "LOST" promises an immersive blend of entertainment and intellectual challenge. Join the survivors, unravel the island's secrets, and embark on this thrilling puzzle adventure today!
LOST Word Search Puzzle Online Free [With Answer Key]


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This story is especially for my students. We use two types of cameras, the red Kodaks, and the black Olympus ones. Both have strengths and weaknesses. The red Kodak cameras do not have earphone jacks, and the internal microphone is quite poor. The black Olympus camera instead has both a mic and earphone jacks, and has excellent stereo microphones.
Red Kodak cameras: Through the year, someone will forget to do a sound check, and record their speaking test with the microphone either switched off or pointed away from the speakers.
Black Olympus cameras: The video does not play with sound on Windows Media Player. WMP is a cheap simple player, and so it lacks some important codecs, including the one used by the Olympus cameras. Consequently, you'll need to download and use either:
If you still have problems, please ask.


How To Measure Pressure with Pressure Sensors
Publish Date: Nov 15, 2012 | 159 Ratings | 3.46 out of 5 | PDF
Return to the NI Measurement Fundamentals Main Page
Table of Contents
 1. What is Pressure?
 2. The Pressure Sensor
 3. Pressure Measurement
 4. Signal Conditioning Used To Measure Pressure
 5. References
 6. Next Steps
1. What is Pressure?
Pressure is defined as force per unit area that a fluid exerts on its surroundings.[1] For example, pressure, P, is a function of force, F, and area, A.
P = F/A
A container full of gas contains innumerable atoms and molecules that are constantly bouncing of its walls. The pressure would be the average force of these atoms and molecules on its walls per unit of area of the container. Moreover, pressure does not have to be measured along the wall of a container but rather can be measured as the force per unit area along any plane. Air pressure, for example, is a function of the weight of the air pushing down on Earth. Thus, as the altitude increases, pressure decreases. Similarly, as a scuba diver or submarine dives deeper into the ocean, the pressure increases.
A pressure measurement can be described as either static or dynamic. The pressure in cases where no motion is occurring is referred to as static pressure. Examples of static pressure include the pressure of the air inside a balloon or water inside a basin. Often times, the motion of a fluid changes the force applied to its surroundings. Such a pressure measurement is known as dynamic pressure measurement. For example, the pressure inside a balloon or at the bottom of a water basin would change as air is let out of the balloon or as water is poured out of the basin.
Head pressure(or pressure head) measures the static pressure of a liquid in a tank or a pipe. Head pressure, P, is a function solely on the height of the liquid, h, and weight density, w, of the liquid being measured as shown in Figure 1 below.
Figure 1. Head Pressure Measurement
The pressure on a scuba diver swimming in the ocean would be the diver's depth multiplied by the weight of the ocean (64 pounds per cubic foot). A scuba diver diving 33 feet into the ocean would have 2112 pounds of water on every square foot of his body. That translates to 14.7 PSI. Interestingly enough, the atmospheric pressure of the air at sea level is also 14.7 PSI or 1 atm. Thus, 33 feet of water create as much pressure as 5 miles of air! The total pressure on a scuba diver 33 feet deep ocean would be the combined pressure caused by the weight of the air and the water, that would be 29.4 PSI or 2 atm.
A pressure measurement can further be described by the type of measurement being performed. There are three types of pressure measurements: absolute, gauge, and differential. Absolute pressure measurement is measured relative to a vacuum (Figure 2). Often times, the abbreviations PAA (Pascals Absolute) or PSIA (Pounds per Square Inch Absolute) are used to describe absolute pressure.
Figure 2. Absolute Pressure Sensor [3]
Gauge pressure is measured relative to ambient atmospheric pressure (Figure 3). Similar to absolute pressure, the abbreviations PAG (Pascals Gauge) or PSIG (Pounds per Square Inch Gauge) are used to describe gauge pressure.
Figure 3. Gauge Pressure Sensor [3]
Differential pressure is similar to gauge pressure, but instead of measuring relative to ambient atmospheric pressure, differential measurements are taken with respect to a specific reference pressure (Figure 4). Also, the abbreviations PAD (Pascals Differential) or PSID (Pounds per Square Inch Differential) are used to describe differential pressure.
Differential pressure sensors measure pressure are taken with respect to a specified reference pressure.
Figure 4. Differential Pressure Sensor [3]
Back to Top
2. The Pressure Sensor
Because of the great variety of conditions, ranges, and materials for which pressure must be measured, there are many different types of pressure sensor designs. Often pressure can be converted to some intermediate form, such as displacement. The sensor then converts this displacement into an electrical output such as voltage or current. The three most universal types of pressure transducers of this form are the strain gage, variable capacitance, and piezoelectric.
Of all the pressure sensors, Wheatstone bridge (strain based) sensors are the most common, offering solutions that meet varying accuracy, size, ruggedness, and cost constraints. Bridge sensors are used for high and low pressure applications, and can measure absolute, gauge, or differential pressure. All bridge sensors make use of a strain gauge and a diaphragm (Figure 4).
Figure 4. Cross Section of a Typical Strain Gauge Pressure Sensor [3]
When a change in pressure causes the diaphragm to deflect, a corresponding change in resistance is induced on the strain gauge, which can be measured by a Data Acquisition (DAQ) System. These strain gauge pressure transducers come in several different varieties: the bonded strain gauge, the sputtered strain gauge, and the semiconductor strain gauge.
In the bonded strain gauge pressure sensor, a metal foil strain gauge is actually glued or bonded to the surface where strain is being measured. These bonded foil strain gauges (BFSG) have been the industry standard for years and are continually used because of their quick 1000 Hz response times to changes in pressure as well as their large operating temperature.
Sputtered strain gauge manufacturers sputter a layer of glass onto the diaphragm and then deposit a thin metal film strain gauge on to the transducer's diaphragm. Sputtered strain gauge sensors actually form a molecular bond between the strain gauge element, the insulating layer, and the sensing diaphragm. These gauges are most suitable for long-term use and harsh measurement conditions.
Integrated circuit manufacturers have developed composite pressure sensors that are particularly easy to use. These devices commonly employ a semiconductor diaphragm onto which a semiconductor strain gauge and temperature-compensation sensor have been grown. Appropriate signal conditioning is included in integrated circuit form, providing a dc voltage or current linearly proportional to pressure over a specified range.
The capacitance between two metals plates changes if the distance between these two plates changes. A variable capacitance pressure transducer (Figure 5), measures the change in capacitance between a metal diaphragm and a fixed metal plate. These pressure transducers are generally very stable and linear, but are sensitive to high temperatures and are more complicated to setup than most pressure sensors.
Figure 5. Capacitance Pressure Transducer [4]
Piezoelectric pressure transducer (Figure 6) take advantage of the electrical properties of naturally occurring crystals such as quartz. These crystals generate an electrical charge when they are strained. Piezoelectric pressure sensors do not require an external excitation source and are very rugged. The sensors however, do require charge amplification circuitry and very susceptible to shock and vibration.
Figure 6. Piezoelectric Pressure Transducer [4]
A common cause of sensor failure in pressure measurement applications is dynamic impact, which results in sensor overload. A classic example of overloading a pressure sensor is known as the water hammer phenomenon. This occurs when a fast moving fluid is suddenly stopped by the closing of a valve. The fluid has momentum that is suddenly arrested, which causes a minute stretching of the vessel in which the fluid is constrained. This stretching generates a pressure spike that can damage a pressure sensor. To reduce the effects of "water hammer", sensors are often mounted with a snubber between the sensor and the pressure line. A snubber is usually a mesh filter or sintered material that allows pressurized fluid through but does not allow large volumes of fluid through and therefore prevents pressure spikes in the event of water hammer. A snubber is a good choice to protect your sensor in certain applications, but in many tests the peak impact pressure is the region of interest. In such a case you would want to select a pressure sensor that does not include overprotection. [3]
Back to Top
3. Pressure Measurement
As described above, the natural output of a pressure transducer is a voltage. Most strain based pressure transducers will output a small mV voltage. This small signal requires several signal conditioning considerations that are discussed in the next section. Additionally, many pressure transducers will output a conditioned 0-5V signal or 4-20 mA current. Both of these outputs are linear across the working range of the transducer. For example both 0 V and 4 mA correspond to a 0 pressure measurement. Similarly, 5 volts and 20 mA correspond to the Full Scale Capacity or the maximum pressure the transducer can measure. The 0-5V and 4-20 mA signals can easily be measured by National Instruments Multi-function Data Acquisition (DAQ) hardware.
Back to Top
4. Signal Conditioning Used To Measure Pressure
As with any other bridge based sensor, there are several signal conditioning considerations in order to accurately measure pressure. It is important to consider the following:
 - Bridge completion
 - Excitation
 - Remote sensing
 - Amplification
 - Filtering
 - Offset
 - Shunt Calibration
Each of these considerations are addressed thoroughly in the Measuring Strain with Strain Gauges tutorial linked below.
Once you have obtained a measurable voltage signal, that signal must be converted to actual units of pressure. Pressure sensors generally produce a linear response across their range of operation, so linearization is often unnecessary, but you will


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You are at: CarrTracks website Library section.
Railroads made great strides during the early part of the 20th Century in adding automatic block signal systems to their lines to improve safety. The Southern Pacific was one of the leaders in installing automatic block signals. The first automatic block signals on the West Coast were installed on the SP in 1904 between Oakland and Port Costa. SP only had automatic block signals on 3% of its main lines in 1902 (102 miles). By 1912 it had 75%, over 3,000 miles. In 1907 the US railroads installed automatic block signals on 2,005 miles of single track and 1,424 miles of two or more main tracks. The top company was the SP which installed automatic block signals on 991 miles of single track and 87 miles of double track that year. Second on the list was the UP with 431 miles of single track and 191 miles of double track. Subsidiary lines OSL installed 301 miles of automatic block signals and OR&N with 118 miles. Between 1905 and 1914 the US railroads had been installing an average of 2,448 miles of automatic block signals per year. This dropped to 1,748 miles per year during the 1915 to 1918 period.
This is a list of the number of miles (single or double track) protected by automatic block signals and the type of signals used on some of the major railroads in the West as of January 1, 1931. Total is the total mileage for the railroad: mainlines and branches.
SSW had just 1.6 miles of color light signals.


Electrical Energy: The Negative Effects Of Electrical Power Plants
983 Words4 Pages
A long time ago, people lived in harmony with nature. By using the natural resources modestly, they lived in accordance with nature laws. But the civilization development, growing population on earth and the industrial revolution, results in humankind domination over nature, and produce unseen technological and economical progress that has negative environmental impact. Besides the technological advancement, mother earth still suffers and loses her potentials. Man of today is faced with enormous environmental problems which creator is he and only he. Man is victim of his own technological prosperity. This progress needs more and more energy, especially electrical. Electrical energy can be produced in different types of power plants, such as coal and fossil fuel plants, nuclear, hydro, wind and solar plants. Furthermore, the usage of power plants is very contradictory because on the one hand, it satisfies the increasing humankind's needs for electrical power, but on the other hand, the manufacturing output harms the environment. So, which power plant generates larger amount of needed electrical energy and has most negative environmental influence and why? We have the responsibility to minimize that negative impact on the environment and people should produce electrical energy with renewable power plants.. According to the level of negative influence on environment, generally there are three groups of electrical power plants. The first group consists of thermo power plants
More about Electrical Energy: The Negative Effects Of Electrical Power Plants
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A space is $F_\sigma$-discrete space if it is the countable union of closed discrete subspaces. Is it true that every subset of an $F_\sigma$-discrete space is of the type $G_\delta$?
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The answer is yes. Suppose that $X$ is an $F_\sigma$ space as you have defined it, so that $X=\bigcup_n X_n$, where each $X_n$ is a closed discrete space. Suppose that $Y\subset X$ is any subset. For each $n$, note that $X_n-Y$ is closed in the discrete space $X_n$ and hence also closed in $X$, and so the complement $U_n=X-(X_n-Y)$ is open in $X$. Furthermore, $\bigcap_n U_n=Y$, since $Y\subset U_n$ and anything not in $Y$ is in some $X_n$ and hence thrown out of that $U_n$. So $Y$ is a countable intersection of open sets and hence $G_\delta$.
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Yes, since closed discrete sets are hereditarily closed. Let $X$ be the space and $E_n$ the closed discrete sets, so $X = \bigcup\limits_{n=1}^\infty E_n$. Then given $S \subseteq X$, each $E_n \setminus S$ is still closed, so $S = \bigcap\limits_{n=1}^\infty (E_n \setminus S)^\complement$ shows that $S$ is a $G_\delta$.
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As an elementary teacher, I often took the whitest sand which I could buy. Then I mixed food coloring with sand in a baggie. After that I dried the sand on a metal tray in the oven at 225 degrees. Stir a couple of times to make sure it all completely dries.
Use plain table salt & colored sidewalk chalk. Pour the salt into a shallow container, "rub" the chalk over it, before you know it you have colored "sand". My Girl Scouts loved doing this sand art craft.
You take regular "play sand", put it in a plastic bag, add food coloring, shake to color.
Back when I was a kid, we did a similar project making colored salt. Using colored chalk, put a small amount on some paper and rub the salt with the side of the chalk. Continue rubbing the salt until it is the color you desire. Then we used the colored salt the same as you would use colored sand.
I know its not sand but I would imagine you could try this with sand and see what happens.
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Are you nervous about proposing a contract to your client? Among the many importance and values of having one are as follows: a contract provides a well-written detailed agreement of each party's responsibilities. It binds both parties to their duty as stated on the agreement as well as agreed schedule or time frame. It ensures secured payment for virtual assistant services rendered. During recourse moments when relationships between client and VA falter, you can use the said agreement to demand payment.
A virtual assistant agreement is a document between two parties, the virtual assistant and the client for a contractual working relationship. Virtual assistants can help with almost anything an in-person assistant can. Information such as required hours, can be included if applicable. In an arrangement like this, standard contractual clauses are also included, like choice of law and place.
In this document, basic identifying info regarding the parties will be entered, like names and address details. Then, details about the actual work and the virtual assistance services, like what the projects are, deadlines, milestones, fees info, etc., will be included. After this document is filled out, it must be printed in order that both parties can sign it. Then, a best practice is for both parties to keep a copy.
By setting out a clear agreement between you and the client, both parties know exactly where they stand, what's expected, who has the rights to what, when payment must be made, how to terminate the agreement, and so on.


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Know how to use "fewer" and "less"? Find out.
Systems or components, possibly from different origins, working together to perform some task. Interworking depends crucially on standards to define the interfaces between the components. The term implies that there is some difference between the components which, in the absence of common standards, would make it unlikely that they could be used together. For example, software from different companies, running on different hardware and operating systems can interwork via standard network protocols.


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Creative chldren's story about the relocation of gopher turtles. This story is written in the turtles perspective - entertaining and educational. Great for kids ages 4-12.
Monsters in the Meadow
By Amy Sellers
32 Pg Picture book: grades 1-4
Pg 1- George was excited about the rainy season approaching. This meant the dry and tasteless grass just outside of his hole would soon turn lush, tasty and tender. His goal every season would be to eat as many of the new sprouts as he could before the grass grew tall, tough and seedy.
Pg 2 -He spun around in the cozy hole he dug which caused a dust cloud to rise. All of the little creatures sharing the tunnel leading to his hole scurried up and out to escape the spoiled air. First Edgar, the cranky squirrel popped his head out of the hole to make sure there were no wolves or snakes lurking near.
Please email to request the remainder of the story. amycsellers.yahoo.com


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Fly masks paired with an insect repellant, can greatly reduce the amount of stress faced by your horse during fly season. An alternative to traditional insect repellants, we also carry feed throughs which when ingested can help ward off pesky insects without the use of sprays.
Dr. Timothy Gibb, Clinical Professor of Entomology at Purdue Agricultural University in Indiana, explained: "Fly masks are used to relieve the stress that a horse deals with when continually fighting flies – primarily the face fly. Face flies are persistent and annoying while they feed around the eyes and nose of horses. They are capable of transmitting eye-worm to horses but this is not common. The mask simply acts as a physical barrier between the horse and the flies."


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What does square waves in the ocean mean?
Square waves are the result of two sets of wave systems blending with each other at differing angles. They usually form when two different weather systems meet up and their winds cause the wave grids to form. The resulting currents can wreck ships and pose a threat to people in the water.
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The Ditto Machine
A spirit duplicator (also referred to as a Ditto machine ) was a low-volume printing method used mainly by schools and churches. The term "spirit duplicator" comes from the alternative term for alcohols, which is "spirits." Alcohols were a major component of the solvents used as "inks" in these machines. The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld. The best-known manufacturer in the United States was Ditto Corporation of Illinois, hence that name.
A ditto machine used a solvent like methylated spirits or ammonia to transfer ink from the master copy (the template, if you will) onto other pieces of paper.
The master copy was a smooth, waxy piece of paper which was thickly inked when printed. The procedure for printing on a master was like the reverse of a carbon-copy; instead of writing on the normal paper and having the carbon underneath, the text and pictures were printed onto carbon paper of varying colours to transfer print to the master. If you want to know exactly how thickly a master was inked, put your printer on the best quality and print about two or three passes onto the same sheet of paper (so that you are printing over the previous printing, I mean).
The master was then wrapped around a drum, and the solvent was applied as the drum rotated. The solvent either softened or melted the ink so that just enough of it would stick to the blank sheets of paper. A lot of the copies produced in this way came out with purple ink because purple "provided the best contrast" As you can see in the following photo Ditto copies were far from easy to read.
Both the isopropanol and the methanol found in ditto solvents are toxic substances. These chemicals can cause a host of medical problems when humans are improperly exposed. Material Safety Data Sheet (MSDS) guidelines recommend the use of personal protective equipment during exposure to methanol, however, most chemists work with methanol and isopropanol wearing only medical exam grade gloves, goggles and a working fume hood as the chief, no-ingested or inhaled reaction with methanol is limited skin irritation.
Ditto machines were popular in schools and churches as no electricity was needed to make quick stinky copies. Nothing smells quite like a fresh slightly wet Ditto copy.
They have gone the way of the typewriter and the dictaphone.
They Always Come Back:
Thanks to the efforts of this site they are not forgotten.


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- More Labs
There exists one test project for each cultivate project. Additionally you need to checkout the cultivate.test project, which contains common files for all tests. The following directories may exist in each project:
For writing prolog tests take a look at the MisnamedTestCaseTest example in cultivate.basic.test:
Creation of a new test consists of 4 steps:
First you need to write your testdata. Do this by creating a new testdata-* src folder and adding it to the build path. Now write your packages and classes. Afterwards you must run the generator-factbases-project.launch via the eclipse launcher menu. This will create the file *.qlf in the factbases directory. Now you can write your test by extending the AbstractPrologTestCase. It will automatically consult the prolog file prolog/load.pl of your project. Additionally you have the following helper methods to use:
For executing predicates in a changing context, the
ContextualPredicate class is provided. it supports the following methods:
IMPORTANT: Before you can run your tests with JUnit you have to alter _URL_.cs3.cultivate.test.framework/test.properties to match the correct paths.


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by Tierra M. Ragland
In the past couple of months, the rights and issues of Trans* students have made it to the forefront of mainstream news and social media. Facing an issue common to many transgender youth, the highest court in Maine ruled that a transgender student would be allowed to use the bathroom in accordance with her gender identity, an issue faced by many transgender youth. Right here in Charlotte, East Mecklenburg High School crowned the first ever transgender homecoming King. These stories address gender identity, cis-gender privilege, and the struggle of Trans* youth for equal rights, visibility, and legitimacy in mainstream society. Although these issues have made national news, many people are unaware of the inequality in treatment of Trans* students. This issue prompted two student organizations at the Charlotte School of Law to organize a panel on Trans* student rights to promote awareness of these social justice issues and provide students with the tools to get involved.
On Tuesday, February 4th, the LGBT Legal Society and the ACLU at Charlotte Law hosted a panel on Trans* student rights. Presenters for the event included Attorneys Kelly Durden and Sarah Demarest from the Freedom Center for Social Justice LGBTQ Law Center and Josh Burford, Assistant Director of Sexual and Gender Diversity at the University of North Carolina at Charlotte.
The purpose of the event was to educate the Charlotte School of Law community on the issues faced by the Transgender[i] community, specifically in a school setting; there were nineteen students in attendance. The event started with an interesting icebreaker wherein the students broke into smaller groups and answered a series of questions about one person in the group based on their car keys. The icebreaker addressed the problem with stereotypes and the importance of self-identity. Josh Burford's presentation educated the audience on queer history and language. The beginning of the presentation addressed the importance of language to illustrate how, during different points in history for the purpose of identity and visibility, the LGBTQ community has adopted different words to define or redefine their sexual orientation and gender identity. Burford also addressed the tension within the community with the use of the word "queer" as a term of agency or term of negativity. He also addressed how marriage equality being the "main" issue in the LGBTQ community does not address the issue of Trans* people in an effective way. Mr. Burford's presentation was a great lead-in to the attorneys' presentation on Trans* student rights within the academic setting.
Durden and Demarest educated students on the issues facing Trans* students in schools. The following issues were addressed during the presentation: access to restrooms congruent with gender identity, legal name change, housing stability, exclusion from nondiscrimination policies, a dropout rate twice that of cis-gender students, sexual assault, and the criminalization of Trans* women. Almost all of the problems faced by the transgender community are centered on transphobia.
Bathrooms are an issue for the Trans* community only when they are denied access to facilities that are not consistent with their gender identity. For example, if a student is assigned the sex of male at birth but identifies as female, she then should be allowed to use the bathrooms designated female. Denying Trans* students access to facilities can lead to fear, threats, self-harm, and violence. This problem can also be solved with gender-neutral bathrooms.
Legal Name changes are available to everyone but are exceedingly important to the Trans* community for two main reasons: safety from being outed in a classroom setting and allowing Trans* individuals to choose a name aligned with their gender identity. If a student has not taken the steps to legally change their name, many schools do not have policies to protect students from being outed or allow students to use of preferred names or pronouns. Trans* students are often not protected in schools' non-discrimination policies because such policies lack protection for sexual orientation or gender identity.
Attorneys Kelly Durden and Sarah Demarest not only educated on Trans* student rights but also provided the audience with ways to effectively advocate for Trans* student rights. The first step is continuing to educate ourselves by attending events similar to the Trans* student rights panel. Charlotte School of Law students as future attorneys or advocates can advocate in formal ways by working to change polices in the community to make them more Trans* inclusive. Students can get involved by joining local social justice organizations in the school and throughout North Carolina. Last but not least, students can volunteer at Freedom Center of Social Justice LGBTQ Law Center and other professional organizations working to improve the lives of the Transgender community.
The lesson from both presentations is that the laws and policies within the education system and many other parts of societies provide no protection, inclusion, or safe space for Trans* youth. In a world of people struggling to find themselves, to tell their own story, to be seen as legitimate, the existence of Trans* people are legitimate not because we as a society make it so, but because they say so and that is really all that matters.
 I hesitate to use the words "transphobia" and "homophobia" because I do not believe that "phobia" or fear of a group of people properly addresses the everyday reality of the violence, discrimination, and hatred experienced by members of the LGBTQ community.
[i] Within this blog there may have been be words unfamiliar to the reader. The following definitions are provided for clarity:
LGBTQ: An abbreviation for "Lesbian, Gay, Bisexual, Transgender, and Queer" A term often used to be more inclusive of the diversity within the community.
Transgender: An umbrella term that encompasses people who experience and/or express their gender differently from conventional or cultural expectations. Transgender people can be any race, age or sexual orientation. Often written as "Trans*" to be inclusive of the diversity within the transgender community.
Sex: Gender marker assigned at birth.
Gender Identity & Expression: How one self-identifies and chooses to express their gender often through dress, grooming, or social interaction. This may or may not be connected to the sex assigned at birth.
Cis-Gender: When one's gender identity and sex assigned at birth are congruent.
Gender Binary: The classification of sex and gender into two distinct, opposite and disconnected, forms of masculine and feminine.


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An ancient Italian town, which disappeared after its abandonment 1,500 years ago and now lies buried underground, has been mapped by researchers, revealing the location of its theatre, marketplace and other buildings.
Originally founded as a Roman colony in the 4th century BCE, the site of Interamna Lirenas lies in the Liri Valley in Southern Lazio, about 50 miles south of Rome itself. After it was abandoned around the year 500 CE, it was scavenged for building materials and, over time, its remains were completely lost from view. Today, the site is an uninterrupted stretch of farmland, with no recognisable archaeological features.
Now, researchers have successfully produced the first images of the ancient site, using geophysical methods that allowed them to look beneath the surface of the earth and map the layout of the entire settlement, which spans 25 hectares.
The resulting pictures have already thrown up a few surprises. Earlier scholars had previously imagined that the Roman town of Interamna Lirenas was something of a sleepy backwater, but the large marketplace and theatre instead suggest that, in fact, it was a bustling economic and social centre in its own right.
"Having the complete streetplan and being able to pick out individual details allows us to start zoning the settlement and examine how it worked and changed through time," Martin Millett, Laurence Professor of Classical Archaeology at the University of Cambridge and Fellow of Fitzwilliam College, said.
"It shows that this was a lively and busy place, even though most scholars have reckoned that it was marginal and stagnating. We have also carried out research in the surrounding countryside which adds to the picture because it shows that the nearby farmland was thriving as well."
The images are the result of a project which began in 2010 that aims to understand more about what happened in towns established by the Romans as colonies in Italy following her conquest. This research is led by Millett and Dr Alessandro Launaro (British Academy Postoctoral Fellow and Fellow of Darwin College) in collaboration with Dr Giovanna Rita Bellini (Director of the Archaeological Area of Interamna Lirenas, Italian State Archaeological Service), the British School at Rome and the Archaeological Prospection Services of Southampton University. It has been generously supported by the British Academy, the Faculty of Classics (University of Cambridge), the McDonald Institute of Archaeological Research (University of Cambridge) and the town of Pignataro Interamna.
Interamna Lirenas is an enticing case study because, in spite of its size, it did not expand significantly during the high point of Rome's Imperial age, meaning that it retained much of its original colonial shape and features.
Thanks to antiquarian research, archaeologists have long since known that a town existed on the site, but it has never been excavated. One reason is that until relatively recently, experts believed that all Roman colonial settlements followed the same template – something which the new pictures from Interamna Lirenas are now helping to question.
Knowing that a full-scale excavation of such a large area would be impractical, the research team decided to carry out a systematic geophysical analysis instead.
The main techniques they used were magnetometry and Ground Penetrating Radar (GPR). Magnetometry measures changes in the earth's magnetic field caused by different features beneath the surface, and allowed the researchers to identify the town's overall layout, many individual buildings and a wide open area in the settlement's centre – its forum or marketplace.
GPR sends electromagnetic radar waves through the soil to search for changes in its composition and the presence of structures. It does this by measuring the time in nanoseconds that elapses between a radar wave being sent and the reflected wave returning.
This technique was applied after the initial survey revealed the existence of a large building at the northern corner of the forum that the researchers could not make out. GPR analysis revealed that the building had several walls arranged in a radial pattern, creating a semicircular seating area. This conclusively proved that they were looking at the remains of a Roman theatre. Judging by its structure, it is believed to date from some time around the turn of the First Millennium.
Major public buildings of this type strongly suggest that, far from a backwater, Interamna Lirenas was in fact an important urban centre in its own right. In addition, the images add to growing evidence that Roman colonial settlements were more varied than some scholars have previously believed. As such sites are uncovered, it is becoming clear that even two colonial towns in close proximity to one another could often be quite different.
The site of Interamna Lirenas itself, for example, lies close to the remains of another settlement, Fregellae. Both were built astride the Via Latina, the principal road running south-east from Rome. Yet despite certain similarities, the new results from Interamna Lirenas reveal important differences, including the position and plan of its market-place which includes a dominant temple and adjacent theatre.
These features matter, Millett argues, because the traditional view was that each colonial settlement had a standard template so that Rome could project a certain image of itself for the benefit of a subject population. Yet the new pictures from Interamna Lirenas show how different towns were designed according to equally different ideas about how a colonial town should look, and what the community's priorities should be.
The Cambridge team is now about to embark on a five-year project which will try to confirm this conjecture, and answer other questions, using further geophysical analysis. The first proper archaeological excavation at Interamna Lirenas is now also being planned.
Further studies should also help to confirm how many people lived in the settlement at different times. "Part of our analysis involves trying to say which areas were used for housing and what types of houses they were," Millett said. "Until we have been able to do this it will be difficult to put a firm figure on the population. However, we are talking about a community of a few thousand people."
The original article has a little slide show of the work in progress and those maps that geophysical surveys provide …


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Definition of national bank in English:
1 another term for central bank.
- In Serbia 1992 the national bank issued single bank notes of 500 billion Serbian dinars.
- Of course national banks cannot file for bankruptcy.
- A supporter of the Glorious Revolution, he was engaged during the Nine Years War in government finance and pressed upon the government the establishment of a national bank to help finance the war.
1.1(In the US) a commercial bank which is chartered under the federal government and is a member of the Federal Reserve System.
- All national banks and member banks of the Federal Reserve System are required to join.
- The second major feature of campaign finance regulation is bans on contributions by corporations, national banks, unions, Federal government contractors, and foreign nationals.
- Calling itself the Federal Reserve, so as to seem official, it replaced the national bank system.
Definition of national bank in:
- US English dictionary
What do you find interesting about this word or phrase?
Comments that don't adhere to our Community Guidelines may be moderated or removed.


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Shaul Stampfer (1948–) is a researcher of East European Jewry specializing in Lithuanian yeshivas, and Jewish demography, migration and education.
Shaul Stampfer, born in Atlanta, Georgia, graduated from Lincoln High School in 1965, received his BA from the Yeshiva University in 1970 and his Ph.D. from the Hebrew University of Jerusalem in 1982. Prof. Stampfer currently resides in the Ramot neighborhood of Jerusalem.
In _PHONE_ Stampfer was a head of the Institute for Jewish Studies in Moscow and helped to establish the city's Jewish University. Stampfer is currently a professor of Soviet and East European Jewry at the Hebrew University. His book on Lithuanian yeshivas (published in Hebrew in 2005) has been translated into English and is scheduled for publication by the Littman Library of Jewish Civilization.
- "The Pushke and Its Development," Cathedra 21 (Oct. 1981): 89–102 (in Hebrew).
- "The 1764 census of Polish Jewry," Bar-Ilan 24–25 (1989): 41–147.
- "The Geographical Beckground of East European Jewish Migration to the United States before World War I," in Ira A. Glazier and Luigi De Rosa (eds.), Migration across Time and Nations: Population Mobility in Historical Contexts (New York & London, 1986), pp. 220–230.
- "Literacy Among East European Jewry in the Modern Period: Context, Background and Implications" in: S. Almog (ed.), Transition and Change in Modern Jewish History: Essays Presented in Honor of Shmuel Ettinger (Jerusalem, 1987), pp. 63–87 (in Hebrew).
- "The Social Implications of Very Early Marriage in Eastern Europe in the Nineteenth Century," in Ezra Mendelsohn and Chone Shmeruk (eds.), Studies on Polish Jewry: Paul Glikson Memorial Volume(Jerusalem 1987), pp. 65–77 (in Hebrew).
- "Heder Study, Knowledge of Torah, and the Maintenance of Social Stratification in Traditional East European Jewish Society," Studies in Jewish Education 3(1988): 271–289.
- "Remarriage Among Jews and Christians in Nineteenth-Century Eastern Europe," Jewish History 3,2(1988): 85–114.
- "L'amour et la famille chez les Juifs d'Europe orientale a l'epoque moderne," in Shmuel Trigano (ed.), La Societe Juive A Travers L'histoire, vol. 2 (Paris 1992), pp. 435–468.
- "Gender Differentiation and Education of the Jewish Woman in Nineteenth-Century Eastern Europe", Polin 7 (1992): 459–483.
- "Patterns of Internal Jewish Migration in the Russian Empire," in Yaacov Ro'i (ed.), Jews and Jewish Life in Russia and the Soviet Union (Ilford, 1995), pp. 28–47.
- "Dormitory and Yeshiva in Eastern Europe," in Religious Dormitory Education in Israel (Jerusalem 1997), pp. 15–28 (in Hebrew).
- "Hungarian Yeshivot, Lithuanian Yeshivot and Josef Ben David," Jewish History 11,1(1997): 131–141.
- "The 1764 Census of Lithuanian Jewry and What It Can Teach Us," Papers in Jewish Demography 1993 (Jerusalem 1997) pp. 91–121.
- "Aspects of Population Growth and Migration in Polish-Lithuanian Jewry in the Modern Period," in The Broken Chain / Polish Jewry Through the Ages (Jerusalem 1997) (in Hebrew).
- "Jewish Population Patterns in Pre-Partition Lithuania and Some of Their Implications," Scripta Hierosolymitana 38(1998)/ Studies in the History of the Jews in Old Poland in honor of Jacob Goldberg, pp. 189–223.
- "What Happened to the Extended Jewish Family? Jewish Homes for the Aged in Eastern Europe," Studies in Contemporary Jewry XIV (1998): 128–142.
- "Hasidic Yeshivot in Inter-War Poland", Polin 11(1998): 3–24.
- "What actually happened to the Jews of Ukraine in 1648?" Jewish History 17,2 (2003): 207–227.
- "Did the Khazars Convert to Judaism?" Jewish Social Studies 19,3 (2013): 1–72.


You are here:
Groups of SYNC type allow you to apply the same effect to two or more strings simultaneously. (ex: two 250 LED strings placed on two columns of a porch). The applied effects will be synchronized and visually identical even if the two strings are arranged differently. The app will handle the mapping of each of the two strings separately.
 1. Access the "Devices" menu.
 2. Make sure they are all on, marked with the Green status icon.
 3. Recommended: perform the mapping of each individual device PRIOR to include it into the SYNC group
 4. Select all the devices you want to add to the group.
 5. Give your group a name
 6. The group will appear in the device list
Here you can find an useful tutorial:
Previous Scene Group Step by Step Procedure
Next Tips for a perfect mapping


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Have your say on bylaw changes
Auckland Council wants to make sure that Aucklanders can enjoy our region's public places, while keeping safe.
The council is proposing changes to the Public Safety and Nuisance Bylaw to minimise nuisance and safety risks to people when using public places.
The bylaw includes a wide range of issues that Aucklanders encounter daily: from using a drone, activities on a park or a beach, set netting, graffiti and car window washing.
The proposed changes won't alter the council's levels of service to safety and nuisance complaints, but will ensure that the most appropriate legislation is used, and that the bylaw is easier to understand.
"Many Aucklanders may not be aware of this bylaw, but it is wide-ranging and covers many activities that people interact with every day," says Councillor Linda Cooper, Chair of the Regulatory Committee.
"We have recently checked how well the rules in the bylaw are working and identified some improvements."
"The proposed changes aim to remove any unnecessary aspects of the bylaw and streamline regulation, so we don't have multiple rules for one issue. They also help to make the bylaw easier to use and understand."
"We encourage people to have their say, so that we can put in place these changes to make sure the bylaw stays fit for purpose in future," she says.
Some parts of the bylaw are proposed to be revoked or removed (as they are dealt with better by other legislation or Auckland Council bylaws), and other parts are proposed to be amended to improve their effectiveness.
The main proposed changes include:
- clarifying expected behavior and restrictions on people using public places
- prohibiting people from leaving or storing construction materials, shipping containers, consumer goods, and boats in public places
- clarifying how the council sets controls and gives approval for activities on public places
- clarifying which public places the bylaw applies to and enabling organisations in control of those places to approve bylaw exceptions.
Regulation would be streamlined by:
- using national legislation rather than bylaws for car window washing, mind-altering substances, graffiti, noise, fish offal, and street naming and numbering
- moving issues about animals, signage, stormwater and vehicles to existing council bylaws.
Request to government to ban the public sale of fireworks
The council intends to ask the government to ban the sale of fireworks to the general public and wants Aucklanders' views on whether or not they support a ban. Public firework displays would still be allowed. Aucklanders are also able to provide their views on this as part of the bylaw consultation process.
Have your say now
You now have an opportunity to tell us your views. This consultation is seeking public feedback from now until 5 December.
Have your say events are also being held across the region over the next month.
Make a submission and find out more at the Auckland Council website.
What are bylaws and why do we review them?
- Bylaws are rules made by local councils that affect the way we live, work and play.
- As a statutory requirement, bylaws are reviewed every five to 10 years. This process involves public consultations to make sure our bylaws are useful and reflect what Aucklanders need.
- Some of these bylaws are no longer needed as other legislation has become operative.


Psychological Implications of Motherhood and Fatherhood in Midlife: Evidence from Sibling Models
Pudrovska, Tetyana
Working paper no. 2007-02
Using a sample comprising full, twin, half-, step-, and adopted siblings, I examine psychological consequences of motherhood and fatherhood in midlife. My analysis includes between-family models that treat siblings as independent observations, and within-family models accounting for unobserved shared genetic and environmental endowments that may confound the relationship between parenthood and well-being. Further, I examine whether the psychological impact of parenthood varies based on siblings' genetic similarity. The findings reveal that parenthood has similar psychological implications for middle-aged mothers and fathers. The main differences arise from specific structural contexts of parenthood. The association between parenthood and mental health at midlife partly reflects shared and nonshared genetic influences. In contrast, shared early-life environment does not explain the psychological impact of parenthood.


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ST. JOHN'S, N.L. - Genetic tests confirm that a large canine shot on Newfoundland's Bonavista Peninsula in March was a wolf that probably made it to the island on ice, provincial officials said Friday.
The province's Environment Department said DNA testing carried out by Memorial University and the University of Idaho has verified that the 37-kilogram animal was a Labrador wolf.
Wolves became extinct on the island around 1930. They have been known to occasionally arrive from Labrador, though there is no evidence of a breeding population.
"We can only speculate on how this wolf arrived on the island of Newfoundland, but most likely it travelled from Labrador on sea ice to the island," Environment Minister Terry French said in a statement.
"Wolves are known to travel long distances and with the number of polar bears coming ashore in Newfoundland this spring, sea ice was plentiful enough to provide a travel route for a Labrador wolf."
Earlier this month, genetic testing confirmed that an animal shot in April in northern New Brunswick was a wolf, marking the first confirmed wolf sighting in that province in 150 years.
Officials said that animal could have arrived on an ice floe or was someone's illegal pet.


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noise is random. According to this argument, if the VBW is 1Hz then we should NOT subtract the correction for 30Hz Resolution Bandwidth (RBW, see above on the calculation method), because this averaging procedure undertaken by the VBW process is already taking into account the correction; effectively the displayed value is already normalized to 1Hz if we use VBW = 1Hz.
2) A counter-argument says that what the display is actually showing at each lit pixel, is the noise power in the 30Hz resolution bandwidth. If you average the noise power over multiple readings, then the average of the noise power will improve (have less uncertainty) which will make the measurement of the noise power less noisy - but the average level itself will not be changed. So effectively: averaging decreases the noise on the noise power measurement, but doesn't affect the noise power measurement itself; then the correction factor for the 30Hz RBW Is still needed.
I wasn't entirely convinced and wanted to see for myself on the screen by actual observation, to prove it one way or the other. The measurements in the three photographs below are with the equipment unchanged, the ONLY change is the VBW setting which is changed from 1Hz (left) to 10Hz (middle) to 100Hz (right). If the former theory is correct (no correction required for the RBW because VBW already takes care of it), then changing from 1Hz VBW to 10Hz VBW will increase the level of the noise by 10dB (10 x log 10). A further increase of 10dB will apply when we increase the VBW from 10Hz to 100Hz.
To make this clear I have drawn a white line on each of the photos, to indicate where the argument (1) would expect the noise power measurement to be. The white box in the center is also drawn on by me, and indicates where the passband of the crystal filter lies. Here are the photographs:
What can clearly be seen is that as the VBW is changed from 1Hz to 10Hz and then 100Hz, the line becomes much more messy (noisy). But the LEVEL of the line remains completely unchanged. The center (average) of the "grass" height doesn't change. This supports entirely, the counter-argument (2) that the noise power measurement is not affected by the averaging inherent in the VBW selection; it only reduces the uncertainty, not the level. Therefore, the correction for the Resolution Bandwidth 30Hz to the normalized standard value 1Hz *IS* still required.
Kevin ZL1UJG also made a similar comparison and reached the same conclusion.
The work of OE3HKL _URL_ also uses 16x averaging and no adjustments are necessary for this in his phase noise calculation, indicating again the same conclusion.
Back to the concern over the crystal filter
Now compare the two images below.
On the right, this image is at 5kHz carrier separation. You can clearly see the noise power line slopes down from left to right. My interpretation of this is that the level of carrier leakage through the crystal filter, due to the stop-band attenuation of the crystal filter simply not being good enough, means that reciprocal mixing of the residual carrier leakage and the phase noise of the spectrum analyzer's own internal local oscillator, is raising the noise floor too much. It makes an accurate measurement close to the carrier impossible; but here even 5kHz away from the carrier is clearly not enough. The filter skirts are thereby suspected of not being sharp enough.
By contrast the second photo (left) shows 20kHz separation. There is a clear pedestal of phase noise at the crystal filter passband and the noise floor is really flat outside that; outside this, the noise floor is the noise floor of the spectrum analyzer. So the measurement can be trusted.
More crystal filters
Refer back up the page to the photo of the 9MHz crystal filters I had in the junkbox. There are 6, all the same size, but three of them had unidentified part numbers on them.
Therefore I made a sweep of each of the crystal filters on the spectrum analyzer, using the 5:16 transformers for matching the spectrum analyzer and tracking generator's 50-ohm ports to the filter's 500-ohm ports. The results are as follows (all frequencies measured in Hz):
|Part number||Center frequency||3dB Bandwidth||Purpose|
|XF-9A||8,999,690||2,350||SSB centered on 9MHz|
|XF-9D||8,999,570||4,460||AM centered on 9MHz|
|Z14-A1||8,998,040||2,400||Lower Sideband (LSB)|
|Z15-A1||9,001,435||2,730||Upper sideband (USB)|
It is evident that of the unknown crystal filters, one is intended for CW, one for LSB and one for USB (or vice versa depending how you look at it). I thought I should hit the carrier with the sharpest filtering possible and so I chose to further investigate the CW filter.
Now I used the QCX "Signal Generator" to generate a signal and sweep it through the filter slowly, recording one measurement at a time (amplitude on the spectrum analyzer screen) to plot the filter shape in a spreadsheet. This is the result:
Compare this to the trace obtained earlier (see above) for the ZF-9A (SSB) filter and you can see immediately that whereas the stop-band attenuation of the ZF-9A filter was around 60dB, this CW filter is much better, at least 90dB. A huge improvement in out-of-band attenuation as well as a narrower filter; this should allow both more accurate measurements as well as closer in measurements (smaller separation from the carrier).
Tests with the new filter
I removed the ZF-9A from my little PCB-boxed project containing the amplifier and filter; and replaced it with the Z13-A1 CW filter. Now admire the resulting trace below. The span is only 5kHz (a zoom in, compared to earlier sweeps above), and the carrier separation is only 1kHz. You can see the width of the noise pedestal is about 500Hz which corresponds to the observed width of the Z13-A1 CW filter. FINALLY this looks now, like the pictures in Kevin's document, with the attenuated peak offset to the side, and the phase noise pedestal coming through the crystal filter in the center. :-)
The CW filter is so narrow and its skirts are so steep, that even at 1kHz spacing, there is no interference from the limitations imposed by the spectrum analyzer's internal phase noise. In fact, I am able to measure even at 500Hz separation and still obtain accurate results.
Testing QCX Phase noise
Now comes a very large number of very tedious time-consuming measurements. For each measurement, I set the QCX signal generator to the desired frequency offset, assuming that 9,998,300 counts as Zero (this is the measured center frequency of this crystal filter). So for example, I set the signal generator to 9,997,800 to measure the 500Hz phase noise. Then I wait for a complete frequency sweep to fill up the display. Then move the cursor to the middle of the 500Hz filter passband, and try to take a measurement. There is some level of estimation involved because from one pixel to the next there is some uncertainty - the "grass" on the spectrum analyzer. I tried to estimate a level which is both at the center of the filter passband and also in the center of the noisy trace. Then recorded that in a spreadsheet and plotted it on a graph.
Measurements are taken at intervals:
- every 500Hz from from 500Hz to 2kHz
- every 2kHz from 2kHz to 10kHz
- every 10kHz from 10kHz to 100kHz
Seven different scenarios were investigated:
1. Standard QCX, with no modifications; a 4,700uF electrolytic capacitor is connected at the QCX power supply terminals
2. Adds a 10uF tantalum capacitor (low Equivalent Series Resistance ESR) at the supply pins of the Si5351A, i.e. parallel with capacitor C2
3. A 470uF electrolytic capacitor in parallel with C2 instead
4. A 300uH inductor in series with the Si5351A supply line, AND a 10uF tantalum capacitor
5. A 300uH inductor in series with the Si5351A supply line, and this time a 470uF capacitor across C2
6. A 300uH inductor and 470uF capacitor at the Si5351A supply (as 5), plus, a 10uF tantalum across the supply of IC4 the QSD FST3253
7. Unlike all of 1-6, this scenario is a standard unmodified QCX with 1m cable to the PSU and NO 4,700uF capacitor at the QCX power terminals
Here are the results:
What is very clear, is that there are no significant improvements available by playing with further cleaning the Si5351A supply: not a tantalum capacitor, not a large electrolytic, and not a series inductor as well or an additional capacitor at the FST3253 supply


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When a bakery found an important part of its cake-icing equipment had been discontinued, it could have caused a major problem. But Freed's Bakery, based in New Hampshire, got in touch with 3-Dimensional Services and got a replacement part 3D printed, instead.
The bakery uses an industrial icing machine, which has a two-colour part that dispenses just the right amount of two different colours of icing onto each of their cupcakes. But the part was beginning to show its age, and the supplier had stopped making them, so 3D printing was the next obvious answer.
First, 3-Dimensional Services had to create a CAD file for the part, since it's not something that many people on Thingiverse tend to make models of. But during the design process, the bakery realised something. Using 3D modelling and printing techniques, they could actually improve their machinery tool, rather than just repairing it. The 3D printing company set to work, changing bits and pieces of the icing machinery - making it lighter, more flexible, and fixing the occasional leakage problem.
Thanks to the quick turnaround of the 3D printed equipment, there was no interruption in the supply of cupcakes with two-toned icing, which means we can all sleep soundly tonight.


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|PostgreSQL 8.2.23 Documentation|
|Prev||Fast Backward||Chapter 31. ECPG - Embedded SQL in C||Fast Forward||Next|
This section explains how ECPG works internally. This information can occasionally be useful to help users understand how to use ECPG.
The first four lines written by ecpg to the output are fixed lines. Two are comments and two are include lines necessary to interface to the library. Then the preprocessor reads through the file and writes output. Normally it just echoes everything to the output.
When it sees an EXEC SQL statement, it intervenes and changes it. The command starts with EXEC SQL and ends with ;. Everything in between is treated as an SQL statement and parsed for variable substitution.
Variable substitution occurs when a symbol starts with a colon (:). The variable with that name is looked up among the variables that were previously declared within a EXEC SQL DECLARE section.
The most important function in the library is
ECPGdo, which takes care of executing most
commands. It takes a variable number of arguments. This can
easily add up to 50 or so arguments, and we hope this will not be
a problem on any platform.
The arguments are:
This is the line number of the original line; used in error messages only.
This is the SQL command that is to be issued. It is modified by the input variables, i.e., the variables that where not known at compile time but are to be entered in the command. Where the variables should go the string contains?.
Every input variable causes ten arguments to be created. (See below.)
An enum telling that there are no more input variables.
Every output variable causes ten arguments to be created. (See below.) These variables are filled by the function.
An enum telling that there are no more variables.
For every variable that is part of the SQL command, the function gets ten arguments:
The type as a special symbol.
A pointer to the value or a pointer to the pointer.
The size of the variable if it is a char or varchar.
The number of elements in the array (for array fetches).
The offset to the next element in the array (for array fetches).
The type of the indicator variable as a special symbol.
A pointer to the indicator variable.
The number of elements in the indicator array (for array fetches).
The offset to the next element in the indicator array (for array fetches).
Note that not all SQL commands are treated in this way. For instance, an open cursor statement like
EXEC SQL OPEN cursor;
is not copied to the output. Instead, the cursor's DECLARE command is used at the position of the OPEN command because it indeed opens the cursor.
Here is a complete example describing the output of the preprocessor of a file foo.pgc (details may change with each particular version of the preprocessor):
EXEC SQL BEGIN DECLARE SECTION; int index; int result; EXEC SQL END DECLARE SECTION;... EXEC SQL SELECT res INTO :result FROM mytable WHERE index = :index;
is translated into:
/* Processed by ecpg (2.6.0) */ /* These two include files are added by the preprocessor */ _TAG_ ; _TAG_ ; /* exec sql begin declare section */ _TAG_ 1 "foo.pgc" int index; int result; /* exec sql end declare section */... ECPGdo(__LINE__, NULL, "SELECT res FROM mytable WHERE index =? ", ECPGt_int,&(index),1L,1L,sizeof(int), ECPGt_NO_INDICATOR, NULL, 0L, 0L, 0L, ECPGt_EOIT, ECPGt_int,&(result),1L,1L,sizeof(int), ECPGt_NO_INDICATOR, NULL, 0L, 0L, 0L, ECPGt_EORT); _TAG_ 147 "foo.pgc"
(The indentation here is added for readability and not something the preprocessor does.)


text:
Family Science Investigation - Algae to Ethanol
Alternative fuel sources are a popular area of discussion in the science and engineering communities. Never before has so much money and research been devoted to the development of alternative fuel sources. This class is designed to teach students about the benefits of alternative fuel sources, specifically the area of biofuels. The Algae to Ethanol class offered by the Natural World Investigate Lab will teach students everything they need to know about the processes of growing algae, harvesting it, and extracting ethanol. We will cover the development of algae ethanol from photosynthesis to alcoholic fermentation and give students hands-on experience using density measurement sticks, fractional distillation systems, spectrometers and pipettes.
Family Science Investigations programs offer families an opportunity to participate together in monthly science classes related to Museum research, including topics in ecology, paleontology, geology and biology. These classes are especially useful for homeschoolers looking for additional reinforcement to curriculum goals, or any family group that simply enjoys learning together!
Program Instructor: Bob Alderink and Colin Brammer, Coordinators for Natural World investigate Lab.
For more information contact Debbie Huston, scheduling coordinator, at _PHONE_.


text:
Why use niobium to make the cavities?
Each one of Jefferson Lab's 338 acceleration cavities cost about $30,000. A good portion of this expense comes from the use of niobium, a relatively rare and expensive metal. Why were the cavities made from niobium when they could have been made from a less expensive metal, such as copper?
Most metals are good conductors of electricity, but they aren't perfect. A property of metals, known as resistance, opposes the flow of electrical currents and converts electrical energy to heat. Unless the metal is part of something that is suppose to get hot (an oven, toaster, space heater or similar device), the heat is a waste product and adds to the expense of operating the device.
Jefferson Lab's cavities work by moving charges back and forth over its surface. This movement of charges is an electrical current. If Jefferson Lab's cavities were made from copper, the cavities would heat, expand and eventually melt. This would not be good for the accelerator.
There are two ways to avoid this problem. The first is to run the accelerator for very short periods of time and allow much longer periods in between for the cavities to cool. Unfortunately, this greatly increases the amount of time it takes to conduct an experiment. The second way is to eliminate the electrical resistance within the cavities. This is why Jefferson Lab's cavities are made from niobium.
Niobium, at room temperature, has electrical resistance and behaves just like copper. If, however, niobium is cooled to very low temperatures, it loses all electrical resistance and becomes what scientists call a superconductor. Since superconductors have no electrical resistance, electrical currents flowing through them do not lose any energy and do not produce any waste heat. If no heat is created, the cavities can not heat up and the accelerator does not need to shut down to allow them to cool. The use of superconductive niobium cavities allows the accelerator to provide a continuous beam of electrons to the experiments.
In order for niobium to become superconductive, it must be cooled far below the freezing point of water. The cavities are immersed in a bath of liquid helium at a temperature of -271°C (-456°F). This is only 2°C above absolute zero, the coldest possible temperature. The cavities and liquid helium are shielded from the heat of the outside world inside large, very well insulated containers called cryomodules.


text:
Schoenberg's Verklärte Nacht: history, editions and analyses
Gustafson, Kirk, 1953-
MetadataShow full item record
This dissertation completed in 1989 is a study containing information surrounding Arnold Schoenberg's original composition of Verklarte Nacht in 1899, his arrangement for string orchestra published in 1917, and his Revision published in 1943. This document is the culmination of the following research: biographical information; a comparative study of the editions listed above; manuscripts; and recordings. A survey of twenty-one different analyses is included along with a chapter regarding the ballet "Pillars of Fire," which was choreographed to the music of Verklarte Nacht.
- Music


matrix theory
for matrix theory in the sense of string theory see at BFSS matrix model and IKKT matrix model
Let AA be a Lawvere theory with generic object TT. For nn \in \mathbb{N}, the full subcategory of AA generated by the cartesian powers of T nT^n is also a Lawvere theory, which we denote by M n(A)M_n(A). In the case of an annular theory (the theory of modules over a ring that we also call AA), this is the construction of n×nn\times n matrices over AA. If we denote by M nM_n the application of this construction to the initial theory (the theory of sets), then we may identify M n(A)M_n(A) with the tensor product theory M nAM_n\otimes A.
It is an amusing exercise to present M nM_n in terms of generating operations and relations between them.
Revised on August 8, 2015 08:27:09 by Urs Schreiber (


text:
The Mission of St. Alegis
The Mission of St. Alegis is to work with nation and local officials, New Testament 'Thought Leaders' and any and all humanitarian groups to build sustainable living cycles for the people that live in and reside within: The Bahamas, The Caribbean Region and the Eastern African Nations.
St. Alegis presses into its efforts via the following Work Flow Diagraph:
- Works with Thought and Community and Church Leaders
- Develops Relationship with Local Pastors in Each Setting
- Emphasis is for the Local Pastor to Become the Local and Regional "Hero"
- Develop Teaching and Instructional Curricula
- Purchase Products and Goods and Send to Local Pastors
- Local Pastors Distribute these Products and Goods as "Seed" Entrepreneurial Projects
- Locals 'sell' the Products and Goods and Build Sustainable Income Sources
- Key Initial Product: Water Filtration and Water Purification Containers and Systems
Hand-in-Hand and Eco-System of Sustainable Compassion and Strength:
St. Alegis is a connector of caring individuals, organizations and congregations from the 'First World' Nations linked directly and inseparably to The 'Poorest of The Poor'. The stated intention of St. Alegis is to eliminate poverty and the plight of unsafe drinking water through empowering local pastors and their existing congregations.


text: Scraplets are alleged to be the deadliest disease known to mechanical lifeforms in the entire galaxy. Like the much larger "Transformer" species, a single Scraplet resembles a tiny robot and can convert into a form built entirely for camouflage — usually in the form of nuts or bolts. However, they will purposefully attach themselves to mechanical objects as fast as possible, first sticking to it like an extremely powerful magnet and then melding with it, replicating itself with incredible speed as it does so. Once embedded they are extremely difficult if not entirely impossible to remove, save for being doused in water, which is a considered a rare and deadly chemical to them from where they come from. If left embedded and uncared for, however, they will consume mechanical organisms nat by nat until they are nothing left but flimsy, rusty scrap.


text:
Make Way For Ducklings
Sunday May 12, 2013
Near the entrance to the Public Garden at Beacon and Charles Streets is the adorable Make Way for Ducklings statue. Anybody who visits the park, a popular destination for both adults and children, will no doubt notice the delightful statues of a Mother duck and her eight ducklings.
It was the popularity of the children's picture book by Robert McCloskey that led to the construction of the statue by renowned sculptor, Nancy Schon. McCloskey was an illustrator first, and author second, so retelling the Ducklings story tends to vary by individual based on their perception of the award-winning illustrations.
Each Mother's Day, a children's procession takes place in the Public Garden, which has become known as the Make Way For Ducklings Parade. The official name of the event is Ducklings Day. Young children dress up in duck-like outfits and trace the steps of the mallards within the Garden. A reservation is required, which allows access to the celebration. The event usually includes entertainment and a snack in addition to the procession. In 2013, the fee is $35 per family through online advance registration, and $40 per family on the day of event. Check-in begins at 10:30 am on Boston Common at the Parkman Bandstand.
Make Way For Ducklings was first published in 1941, and in 1942 it won the Caldecott Medal for its illustrations. More than two million copies of the book have been sold.
This enchanting story tells of how a pair of mallard ducks choose an island in the Boston Public Garden to raise their family. We first meet Mr. and Mrs. Mallard as they begin their search for a place to build their nest. Mr. Mallard suggests several locations, but to Mrs. Mallard, nowhere seems quite right. They decide to rest for the night on an island in the Public Garden lagoon, and then continue their search the next day.
The morning arrives and as the park comes to life, a Swan Boat passes by the ducks. Mr. and Mrs. Mallard mistake the human-powered catamaran for a real swan—at first believing they were snubbed by an arrogant swan—but then happily breakfast on the peanuts that the people on the boat throw to them. Just as Mrs. Mallard decides they should raise their family in the Public Garden, a passing bicyclist almost runs her over, and so their search begins again. After a very tiring day flying around Boston, Mr. and Mrs. Mallard decide to build their nest on an island in the Charles River.
They quickly settle into a routine of visiting the shore to get their daily meal of peanuts from a policeman named Michael. Soon afterwards, the ducks go through their molt and must wait until their feathers grow back before they can fly. In the meantime, eight ducklings are hatched by Mrs. Mallard, called Jack, Kack, Lack, Mack, Nack, Ouack, Pack and Quack.
Mr. Mallard decides it's time to take a trip to investigate the rest of the Charles River and arranges to meet Mrs. Mallard at the Public Garden after one week. While Mr. Mallard is gone, Mrs. Mallard shows her eight children how to swim, dive, and march along as ducks do. Remembering her near collision with the bicycle, she also shows them how to avoid the dangers of these strange wheeled objects.
The week passes quickly by, and Mrs. Mallard and her ducklings begin the journey to meet with Mr. Mallard. However, there are so many cars on Storrow Drive, that it's impossible to cross the busy highway to get to the Public Garden. Fortunately, their friend Michael the Policeman is on hand to stop the traffic and allow them to get across. To ensure the ducks' safety, Michael calls police headquarters and arranges with three other officers to stop all the traffic along the route, and Make Way for the gaggle of mallards. The ducklings march along in line, following closely behind their mother, just as she taught them. The people who see them along the way on Charles Street give them admiring looks and compliment them for being such a lovely family.
The story ends happily ever after with the mallard family making their home in the Public Garden, searching for peanuts and other food by day, and sleeping on their little island at night.
Contact Information & Address:
Make Way for Ducklings Statue
Public Garden, Beacon & Charles Street Entrance, Boston, MA 02108
Ducklings Parade, Sunday, May 12, 2013
Registration at Parkman Bandstand, Tremont & Avery Streets, Boston, MA


Los Angeles teachers' strike: Here's what you need to know
The nation's second-largest school district is on the verge of chaos.
United Teachers Los Angeles – 34,000 educators strong in the schools in question – went on strike Monday as UTLA and the Los Angeles Unified School District have been negotiating a new contract for almost two years with little to show for it.
Teachers picketed their individual schools early Monday and then headed to a rally downtown. Here's what we know about the situation.
Q: Just how big is this strike?
A: LA Unified School District, which covers 710 square miles and is home to 4.8 million residents, serves more than 640,000 K-12 students. (That's more students than the entire state of Wyoming has people.) Some of those students are in charter schools, but nearly half a million are in schools where educators plan to walk out.
LAUSD is the second-largest employer in Los Angeles County. That means this strike will impact hundreds of thousands of people.
The strike comes nearly a year after West Virginia teachers walked out, kicking off a wave of teacher protests across the country. The statewide strike in West Virginia may have been historic, but it was tiny compared with the effort in LA.
Q: Why are teachers striking?
A: Teachers in LA, like those across the country, want bigger paychecks. But their demands go beyond salary increases: UTLA wants more money for counselors, nurses and librarians, plus a reduction in standardized testing and promises of smaller class sizes.
Some teachers have classes with more than 40 students in them.
Another issue for the union: charter schools, which it says take money away from neighborhood schools. Charters have exploded in California, and UTLA wants regulations on charter-school growth.
UTLA points to nearly $2 billion in reserves at LA Unified that the union says can be used immediately to pay for its varying demands.
Teachers in America:No matter where they work, they feel disrespect
Q: Why won't the district give them what they want?
A: LA Unified Schools, led by Superintendent Austin Beutner, offered teachers a 6 percent raise by the second year of a three-year contract. (The union wanted 6.5 percent, plus a year retroactive.)
The district says the nearly $2 billion in reserves is already pledged to a variety of causes, including raises for cafeteria workers and bus drivers. If it met every UTLA demand, the district says, it would go bankrupt – which isn't just bad business, but illegal.
Los Angeles Unified School District Superintendent Austin Beutner talks to reporters at district headquarters following a day of negotiation with United Teachers Los Angeles Monday, Jan. 7, 2019. Teachers in the nation's second-largest school district will strike this week if there's no settlement in long-running contract negotiations that resumed with the superintendent and the head of the union coming to the table in a last-ditch effort to avert a walkout in Los Angeles.
Q: What will happen to the kids?
A: The district plans to keep schools open during the strike.
About 400 substitutes, plus 2,000 credentialed district staff – including administrators who used to be classroom teachers – will help fill the void of the 34,000 striking teachers.
Roughly 80 percent of students in the district rely on their school for lunch, and the schools' administrators want to make sure those students are able to eat. The schools also are committed to providing meals and a safe environment for their more than 20,000 homeless students.
The district has told parents that students will still have instructional hours, but many believe students will be stuck in auditoriums or gyms and made to do worksheets or similar exercises to pass the time.
Q: How are parents responding?
A: Many parents support the union but plan to send their children to school because they have no other choice. They work and have no child-care options during school hours.
Other parents have said they'll hold their kids out of school and not let them cross the picket line. Some parents have even volunteered their homes as a rest stop of sorts for picketing teachers. The district has said that because school is open, students are expected to attend.
Parents Supporting Teachers, a Facebook group started by parents who have decried a lack of money for schools, had nearly 12,000 members as of Saturday afternoon.
Q: How long might the strike last?
A: It's unclear. By hiring subs, the district has prepared for a strike that could last multiple days. But it's tough to know how long parents will put up with a potentially dramatically altered school day, or how many kids will even show up for classes.
The last teacher strike in LA, in 1989, lasted nine days. West Virginia's teacher strike in February lasted 10 days.
In this Saturday, Dec. 15, 2018, photo, thousands of teachers marched and rallied outside Los Angeles City Hall. Teachers in the nation's second-largest school district will go on strike next month if there's no settlement of its long-running contract dispute, union leaders said Wednesday, Dec. 19. The announcement by United Teachers Los Angeles threatens the first strike against the Los Angeles Unified School District in nearly 30 years and follows about 20 months of negotiations. (AP Photo/Damian Dovarganes) ORG XMIT: CADD306
Q: Who's going to win?
A. Again, it's tough to say. California is union-friendly, which would seem to give the teachers a clear advantage. Politicians in Sacramento, the state capital, typically don't make moves unless they have the support of unions.
But LAUSD serves primarily low-income families, who might not be able to keep their kids at home or spare time away from work to picket with teachers. How those parents respond to the strike will determine whether the teachers or district has the upper hand.
Q: Aren't teachers striking all over the country these days? Why is this walkout different?
A: Teachers have been picketing across America, dating back to last February. There have been walkouts and demonstrations in West Virginia, Arizona, Oklahoma, North Carolina, Kentucky, Colorado and Washington state.
But in most cases, those walkouts didn't happen in major urban areas. The LA strike will disrupt daily life in the country's second-most-populous metropolitan area.
LA is also different because teachers are pressuring the district for more money, as opposed to fighting the state Legislature, which happened in states such as Oklahoma.
Other unions around California are paying close attention to Los Angeles, including Oakland, where teachers could strike later this month.


text:
Accurate free and forced rotational motions of rigid Venus
Observatoire de Paris, Systèmes de Référence Temps Espace (SYRTE), CNRS/UMR8630, Paris, France e-mail: _EMAIL_
Accepted: 27 February 2010
Context. The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting because it can be compared with that of Earth for which such a modelling has already been achieved at the milli-arcsecond level.
Aims. We aim to complete a previous study, by determining the polhody at the milli-arcsecond level, i.e. the torque-free motion of the angular momentum axis of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view.
Methods. We use the same theoretical framework as Kinoshita (1977, Celest. Mech., 15, 277) did to determine the precession-nutation motion of a rigid Earth. It is based on a representation of the rotation of a rigid Venus, with the help of Andoyer variables and a set of canonical equations in Hamiltonian formalism.
Results. In a first part we computed the polhody, we showed that this motion is highly elliptical, with a very long period of 525 cy compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we precisely computed the Oppolzer terms, which allow us to represent the motion in space of the third Venus figure axis with respect to the Venus angular momentum axis under the influence of the solar gravitational torque. We determined the corresponding tables of the nutation coefficients of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We showed that the nutation coefficients for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration, which revealed the indirect planetary effects.
Key words: planets and satellites: individual: Venus / celestial mechanics
© ESO, 2010


LAS Links Second Edition Scope and Sequence
LAS Links Second Edition specifies three criteria related to language in academic settings:
 1. Target content areas or strands of academic language:
 1. Foundational Skills
 2. Language Arts
 3. Social Studies
 4. History
 5. Mathematics
 6. Science
 7. Technical Subjects
 2. The linguistic complexity of receptive and expressive language (e.g., word/sound recognition, vocabulary, grammar, discourse features, etc.)
 3. The types of language function and tasks for communicative purposes in a school context (e.g., identifying, comprehending, describing, analyzing, etc.)


text:
Origin of diversity in falling snow
- ISSN: _PHONE_
- DOI: 10.5194/acp-8-5669-2008
This paper presents a systematic way to examine the origin of variety in falling snow. First, we define shape diversity as the logarithm of the number of possible distinguishable crystal forms for a given resolution and set of conditions, and then we examine three sources of diversity. Two sources are the range of initial-crystal sizes and variations in the trajectory variables. For a given set of variables, diversity is estimated using a model of a crystal falling in an updraft. The third source is temperature-updraft heterogeneities along each trajectory. To examine this source, centimeter-scale data on cloud temperature and updraft speed are used to estimate the spatial frequency (m−1) of crystal feature changes. For air-temperature heterogeneity, this frequency decays as p−0.66, where p is a measure of the temperature-deviation size. For updraft-speed heterogeneity, the decay is p−0.50. By using these frequencies, the fallpath needed per feature change is found to range from ~0.8 m, for crystals near −15°C, to ~8 m near −19°C – lengths much less than total fallpath lengths. As a result, the third source dominates the diversity, with updraft heterogeneity contributing more than temperature heterogeneity. Plotted against the crystal's initial temperature (−11 to −19°C), the diversity curve is "mitten shaped", having a broad peak near −15.4°C and a sharp subpeak at −14.4°C, both peaks arising from peaks in growth-rate sensitivity. The diversity is much less than previous estimates, yet large enough to explain observations. For example, of all snow crystals ever formed, those that began near −15°C are predicted to all appear unique to 1−μm resolution, but those that began near −11°C are not.