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John Murrin
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### John Murrin

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It can't be true... can it?

Yes, it is indeed true that the square root of 2 and two thirds is equal to 2 times the square root of two thirds. This particular equation is an example of a prompt on the UK-based website Inquiry maths. The website explains:

Inquiry maths is a model of teaching that encourages students to regulate their own activity while exploring a mathematical statement (called a prompt). Inquiries can involve a class on diverse paths of exploration or in listening to a teacher's exposition. In inquiry maths, students take responsibility for directing the lesson with the teacher acting as the arbiter of legitimate mathematical activity.

Remarkably, this particular prompt was found by a year 10 student of teacher Rachael Read. It is recommended for students with high prior attainment in years 10 and 11. Reportedly, students are quickly hooked in to the prompt, particularly when one of them claims it “works” after checking on a calculator.

There is more discussion of the educational value of this equation, and on the teaching of surds in general, in the original blog post on this topic: http://www.inquirymaths.co.uk/home/number-prompts/surds

The word “surd”, referring to n-th roots, is a Latin translation of a term tracing back to the 9th century Persian mathematician al-Khwārizmī, after whom algorithms are named. He also invented the term algebra (al-jabr in Arabic).

Surds: http://en.wikipedia.org/wiki/Nth_root

(Seen via Cliff Pickover on Twitter.)

#mathematics #education  ﻿
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Cat talent

Cat communication is the transfer of information by one or more cats that has an effect on the current or future behaviour of another animal, including humans. Cats use a range of communication modalities including visual, auditory, tactile, chemical and gustatory.

The communication modalities used by domestic cats have been affected by domestication.

Vocalizations

Cat vocalisations have been categorised according to a range of characteristics.

Schötz categorised vocalizations according to 3 mouth actions: (1) sounds produced with the mouth closed (murmurs), including the purr, the trill and the chirrup, (2) sounds produced with the mouth open and gradually closing, comprising a large variety of miaows with similar vowel patterns, and (3) sounds produced with the mouth held tensely open in the same position, often uttered in aggressive situations (growls, yowls, snarls, hisses, spits and shrieks).

Brown et al. categorised vocal responses of cats according to the behavioural context: (1) during separation of kittens from mother cats, (2) during food deprivation, (3) during pain, (4) prior to or during threat or attack behavior, as in disputes over territory or food, (5) during a painful or acutely stressful experience, as in routine prophylactic injections and (6) during kitten deprivation. Less commonly recorded calls from mature cats included purring, conspecific greeting calls or murmurs, extended vocal dialogues between cats in separate cages, “frustration” calls during training or extinction of conditioned responses.

Miller classified vocalisations into 5 categories according to the sound produced: the purr, chirr, call, meow and growl/snarl/hiss.

Purr

The purr is a continuous, soft, vibrating sound made in the throat by most species of felines. Domestic cat kittens can purr as early as two days of age. This tonal rumbling can characterize different personalities in domestic cats. Purring is often believed to indicate a positive emotional state, but cats sometimes purr when they are ill, tense, or experiencing traumatic or painful moments.

The mechanism of how cats purr is elusive. This is partly because cats do not have a unique anatomical feature that is clearly responsible for the vocalization. One hypothesis, supported by electromyographic studies, is that cats produce the purring noise by using the vocal folds and/or the muscles of the larynx to alternately dilate and constrict the glottis rapidly, causing air vibrations during inhalation and exhalation. Combined with the steady inhalation and exhalation as the cat breathes, a purring noise is produced with strong harmonics. Purring is sometimes accompanied by other sounds, though this varies between individuals. Some may only purr, while other cats include low level outbursts sometimes described as "lurps" or "yowps".

Domestic cats purr at varying frequencies. One study reported that domestic cats purr at average frequencies of 21.98 Hz in the egressive phase and 23.24 Hz in the ingressive phase with an overall mean of 22.6 Hz. Further research on purring in four domestic cats found that the fundamental frequency varied between 20.94 and 27.21 Hz for the egressive phase and between 23.0 and 26.09 Hz for the ingressive phase. There was considerable variation between the four cats in the relative amplitude, duration and frequency between egressive and ingressive phases, although this variation generally occurred within the normal range.

One study on a single cheetah (Acinonyx jubatus) showed it purred with an average frequency of 20.87 Hz (egressive phases) and 18.32 Hz (ingressive phases). A further study on four adult cheetahs found that mean frequencies were between 19.3 Hz and 20.5 Hz in ingressive phases, and between 21.9 Hz and 23.4 Hz in egressive phases. The egressive phases were longer than ingressive phases and moreover, the amplitude was greater in the egressive phases.

It was once believed that only the cats of the genus Felis could purr. However, felids of the genus Panthera (tigers, lions, jaguars and leopards) also produce sounds similar to purring, but only when exhaling. The subdivision of the Felidae into ‘purring cats’ on the one hand and ‘roaring cats ’ (i.e. non-purring) on the other, originally goes back to Owen (1834/1835) and was definitely introduced by Pocock (1916), based on a difference in hyoid anatomy. The ‘roaring cats’ (lion, Panthera leo; tiger, P. tigris; jaguar, P. onca; leopard, P. pardus) have an incompletely ossified hyoid, which according to this theory, enables them to roar but not to purr. On the other hand, the snow leopard (Uncia uncia), as the fifth felid species with an incompletely ossified hyoid, purrs (Hemmer, 1972). All remaining species of the family Felidae (‘purring cats’) have a completely ossified hyoid which enables them to purr but not to roar. However, Weissengruber et al. (2002) argued that the ability of a cat species to purr is not affected by the anatomy of its hyoid, i.e. whether it is fully ossified or has a ligamentous epihyoid, and that, based on a technical acoustic definition of roaring, the presence of this vocalization type depends on specific characteristics of the vocal folds and an elongated vocal tract, the latter rendered possible by an incompletely ossified hyoid.

Meow

The meow is one of the most widely known vocalizations of domestic kittens. It is a call apparently used to solicit attention from the mother.

Adult cats commonly vocalise with a "meow" (or "miaow") sound, which is onomatopoeic. The meow can be assertive, plaintive, friendly, bold, welcoming, attention soliciting, demanding, or complaining. It can even be silent, where the cat opens its mouth but does not vocalize. Adult cats do not usually meow to each other and so meowing to human beings is likely to be an extension of the use by kittens.

Language differences

Different languages have correspondingly different words for the "meow" sound, including miau (Belarusian, Croatian, Hungarian, Dutch, Finnish, Lithuanian, Malay, German, Polish, Russian, Portuguese, Romanian, Spanish and Ukrainian), mnau (Czech), meong (Indonesian), niau (Ukrainian), niaou (?????, Greek), miaou (French), nya (??, Japanese), miao (?, Mandarin Chinese, Italian), miav/miao or mjav/mjau (Danish, Swedish and Norwegian), mjá (Icelandic), ya-ong (??, Korean), ????? / Miya?un_ (Urdu) and meo-meo (Vietnamese). In some languages (such as Chinese ?, mao), the vocalization became the name of the animal itself.

#gif #cats #animals #caturday #caturdayeveryday #caturday2014 #catsrule #catsallovertheworld #catholic #catlovers #animallovers #animalphotography #catphotography #catphotos #catpictures #catpics #lol #funny #funnypics #funnypictures #funnyphotos #funnystuff #ANNIMATEDGIFS   #trendingnow   #lolcats﻿
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And Yet It Moves

A famous story in the history of science is that of the trial of Galileo Galilei.  Galileo believed that the Earth moved around the Sun, but this conflicted with the theological position of the Catholic Church, which held that the Earth was fixed in the center of the universe.  This conflict came to a head when Galileo was put on trial and was forced to renounce his assertion that the Earth moved around the Sun.  As the story goes, after making his public renouncement Galileo muttered under his breath “Eppur si muove!” which in Italian means “And yet it moves!”

There’s no contemporary evidence that Galileo actually said those words, but it makes for a good story.  It also exemplifies the frustration Galileo felt toward Church officials.  Galileo had good reason to believe the Earth moved around the Sun.  He had observed the phases of Venus, which showed that Venus moved around the Sun, and he had discovered four moons around Jupiter.  Both of these observations agreed with the heliocentric model of Copernicus, which held that the Sun was the center of the universe.

Heliocentrism was a huge theological problem for the Church.  It seemed unthinkable that God’s divine creation — humanity — would be placed upon a minor planet, rather than at the fixed center of the physical universe.  Besides, the Bible clearly states (in Chronicles 16 and Psalm 93 for example) that the Earth doesn’t move.

The central dispute between Galileo and the Church was whether Galileo could assert that the Earth really did move around the Sun (that is, as a scientific fact), or whether he should present the idea as merely a hypothesis.  Church officials admitted that Galileo’s observations gave the appearance of moving around the Sun, but argued that appearances could be deceiving.  Galileo, they argued, hadn’t completely proven his hypothesis.  Galileo, on the other hand, thought it was ridiculous to take poetic passages from the Bible literally.

This raises an interesting question: is there an experiment Galileo could have done to prove that the Earth actually moves?  It’s likely that nothing would have convinced the Church at that time, but there is an experiment Galileo could have done to demonstrate the motion of the Earth.  All he would have needed is a large pendulum.  The experiment was devised by Leon Foucault about 200 years after Galileo’s trial.

A simple pendulum consists of a mass hung from a wire or string.  Once released it will swing back and forth at a regular rate.  With friction and air resistance, the swing of the pendulum will die down over time, but this happens slowly for a large and heavy pendulum.  If the Earth were motionless, then a pendulum would swing back and forth in a perfectly straight line.  It’s orientation would never change.

But the Earth rotates, which means everything on the Earth moves around in a circle once a day.  If you are on the equator, you would travel the entire circumference of the Earth in 24 hours.  If you are near the north pole, you would travel only a small circle in 24 hours.  This means that while everything on Earth moves in a circle once a day, things closer to the equator move faster than things closer to the Earth’s poles.  Your speed depends upon your latitude.

As a pendulum swings, it will be slightly closer to the equator at one part of its swing, and slightly farther away at another part.  As a result, the motion of the Earth causes the orientation of the pendulum to shift slightly with each swing, an effect known as precession.  The effect is very small, but it builds up.  After several hours the orientation of the pendulum can be significantly changed.  Watching the precession of a pendulum you can see the direct effect of the Earth’s motion.  Galileo was right after all.

Foucault first demonstrated his pendulum in his cellar.  His experiment gained such popularity that he was soon asked to demonstrate his pendulum in the Pantheon in Paris, where there is a Foucault pendulum to this day.﻿
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Secretive startup Magic Leap demos its augmented reality concept in new video http://goo.gl/ACNDZM

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EXCLUSIVE.﻿
We learned on Monday night that Hillary Clinton exclusively used personal email for official government business.
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In his circles
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Blinded by the Light

One of the common tools of amateur astronomers is a red light used to see charts and telescope settings. The idea behind the use of red light is to maintain dark adaption for nighttime viewing. While red lights can help in that respect, things are quite that simple.

Dark adaption comes in two stages. The first is simply the due to the size of our iris. In bright light our iris closes more to let less light into our eyes, while in dark light it opens up to let in light. This shift can happen in a few seconds. You can experience it, for example, when you enter a house on a bright sunny day. For a few moments things look dark, but you’re eyes adjust pretty quickly.

Real dark adaption happens on a chemical level. Your retina detects light through what are known as rods and cones. The cones come in three types that are differently sensitive to wavelengths, which is how we’re able to detect colors. Rods are more numerous, and are much more sensitive to light. Since rods only come in one type, they aren’t able to give us information about color. Both rods and cones become “blind” to light if they are over exposed. You may have seen this effect when you stare at an image for a while, then look at a white wall or sheet of paper. The after-image you observe is due to the over exposed cones. The chemical reset for cones is fairly quick, so after a few minutes the after-image will fade. For rods, however, the chemical reset can take half an hour or more.

During daylight hours, your rods are over exposed, and so are less efficient. As light gets dimmer, a chemical change allows them to become even more sensitive, and your eyes become dark adapted. If you’ve ever been camping, you might have noticed that as dusk falls the green leaves will appear brighter. This is actually due to your rods becoming dark adapted. Rods are most sensitive at around 500 nanometers, which is in the green to cyan range of the spectrum. In the truly dim light of a dark starry night, your rods become highly sensitive, and the night sky comes alive.

So what does this have to do with red lights? It only takes a brief exposure to bright light for your rods to over expose. Once that happens, you have a half hour or more to regain dark sensitivity, which can seriously hamper your astronomy experience. Since rods are less sensitive to red light (below 650 nanometers) you can use a red light source to view things without ruining your night vision. However it has to be the right kind of red light. Simply taping a red filter over a flashlight isn’t a great solution. Cheap filters don’t block other colors very well, so a bright flashlight with a red filter can still ruin your evening. There are red LED lights and properly filtered red flashlights that are made for astronomical viewing, and these are much more useful. Even then, you don’t want your light source to be too bright.

Although red lights are most commonly used, another solution is to use a cyan-green light. Since this is the region where rods are most sensitive, that might seem counter intuitive, but it’s that sensitivity that makes it useful. Since rods are most sensitive in that color range, you can use a very dim light, and still see things. As long as the light is dim, it won’t over expose your eyes, and your night vision will be maintained.

The best method to preserve dark sensitivity is to simply not use any light source at all. Find a dark place under a dark sky, and simply watch the stars. If you’re patient, the sky will seem to gradually brighten and you’ll be amazed at what you can see.﻿
Why do astronomers use red flashlights? It all has to do with dark adaption, and a bit of chemistry in our eyes.
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From . Perfect! (via )﻿
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I only break out the red pen on special occasions. So when I saw Marco Rubio’s recent op-ed on Net Neutrality, you know I couldn’t resist. It is intentionally misleading, poorly researched, and littered with errors.

See me in my office and I’ll walk you through Net Neutrality.

#fcc   #fccnetneutrality   #netneutrality  ﻿
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On 17 March, ATLAS presented their latest Higgs physics results at an LHC seminar at CERN from data collected during the LHC's first run. The updated results include searches for the Higgs boson in association with top quarks, measurements of the spin and parity, and improved and combined coupling measurements, all showing good compatibility with Standard Model predictions. These results are also being presented at the 50th Rencontres de Moriond ...
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What #NetNeutrality Rules Mean for Consumers.﻿
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New Computer Will ‘Decide If You Receive Healthcare’ http://b4in.org/hG5y

IBM’s Watson computer may soon decide if some individuals receive healthcare or not.

IBM, whose stock price has sunk to its lowest in four years, has recently “announced a \$1 billion investment to establish the new Watson Group.” IBM’s Watson computer processes large amounts of your information to make a better decision for you. Watson is now embedded in the Department of Veteran’s Affairs Data Center in Austin, Texas to “advise doctors on treatments for post-traumatic stress disorder.”

According to their press release, the technology will “transform decision making.” Or said in a different way, if you are a Veteran in need of care, IBM’s Watson will soon make the decision about your health care for you.

Big Data Used Against You

IBM’s Watson can “understand and respond to Big Data.” This is a catch-all phrase that encompasses medical literature, clinical data, personal electronic records, and doctor’s personal comments on patients. For years, it has been an open secret that all of our “Big Data” has been harvested and stored without our consent. This includes every Facebook thought, phone conversation, every purchase, and even household conversations, to name a few. There is no doubt that this “Big Data” is waiting to be used towards withholding or forcing medical treatment at the stroke of a bureaucratic pen in the future.

More http://b4in.org/hG5y﻿