Kevin Clift
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Complex Numbers Interactive Doodle

Christopher Walker sets out to give an insight for beginners into the meaning and usefulness of Complex Numbers โ which are made up of an imaginary part which when squared is negative, and a real number which isn't โ with this Interactive Doodle: https://goo.gl/Hs7hBq

In mathematics, the complex plane or z-plane is a geometric representation of the complex numbers established by the real axis and the perpendicular imaginary axis. It can be thought of as a modified Cartesian plane, with the real part of a complex number represented by a displacement along the x-axis, and the imaginary part by a displacement along the y-axis.

The concept of the complex plane allows a geometric interpretation of complex numbers. Under addition, they add like vectors. The multiplication of two complex numbers can be expressed most easily in polar coordinatesโthe magnitude or modulus of the product is the product of the two absolute values, or moduli, and the angle or argument of the product is the sum of the two angles, or arguments. In particular, multiplication by a complex number of modulus 1 acts as a rotation.

The complex plane is sometimes known as the Argand plane, and geometric plots in the plane as Argand diagrams. These are named after Jean-Robert Argand (1768โ1822), although they were first described by Norwegian-Danish land surveyor and mathematician Caspar Wessel (1745โ1818). Argand diagrams are frequently used to plot the positions of the poles and zeroes of a function in the complex plane.

Argand Diagram (Wikip): https://goo.gl/2bZ1xj

Also, if you haven't already seen it don't miss the more elaborate and fantastic interactive explanation How to Fold a Julia Fractal in this
Related Post: https://goo.gl/JyPNNw

Image: by Oleg Alexandrov https://goo.gl/LG12zb
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Hilary Mantel Reith Lectures 2017

Booker Prize winning novelist and writer, Hilary Mantel, famous for her historical novels, is this year's Reith Lecturer.

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Art can bring the dead back to life, argues the best-selling novelist Hilary Mantel, starting with the story of her own great-grandmother. "We sense the dead have a vital force still," she says. "They have something to tell us, something we need to understand. Using fiction and drama, we try to gain that understanding." She describes how and why she began to write fiction about the past, and how her view of her trade has evolved. We cannot hear or see the past, she says, but "we can listen and look".

More here (text, links, transcript, podcast, download MP3, stream): https://goo.gl/1rXcF5
(Episode one of several)

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My concern as a writer is with memory, personal and collective: with the restless dead asserting their claims. My own family history is meagre. An audience member once said to me, โI come from a long line of nobodies.โ I agreed: me too. I have no names beyond my maternal great-grandmother - but let me introduce her, as an example, because she reached through time from the end of the nineteenth century to form my sense of who I am, at this point in the twenty-first: even nobodies can do this.

She was the daughter of a Patrick, the wife of a Patrick, the mother of a Patrick; her name was Catherine OโShea, and she spent her early life in Portlaw, a mill village near Waterford in the south of Ireland. Portlaw was an artificial place, purpose-built by a Quaker family called Malcolmson, whose business was shipping and corn, cotton and flax. The mill opened in 1826. At one time Portlaw was so busy that it imported labour from London. The Malcolmsons were moral capitalists and keen on social control. Their village was laid out on a plan ideal for surveillance, built so that one policeman stationed in the square could look down all five streets. The Malcolmsons founded a Thrift Society and a Temperance Society and paid their workers partly in cardboard tokens, exchangeable in the company shop. When a regional newspaper suggested this was a form of slavery, the Malcolmsons sued them, and won.

More here (transcript pdf): https://goo.gl/eqjWJv

Image from first link (c) BBC.
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Charles Thacker 1943/02/26 โ 2017/06/12

The pioneering personal computer designer Charles Thacker, a co-inventor of Ethernet, has died at the age of 74 in nearby Palo Alto. In 1972, just like personal computers of today, his Xerox Alta did not require a remote serial monitor since its tilt and swivel portrait screen was mapped directly to its hardware internals, it boasted a GUI supported directly by its OS, a three button mouse, and a detachable keyboard.

Charles Thacker based some, but not all, of the features of the Xerox Alta, on a computer system developed by Douglas Engelbart and demonstrated in 1968. These feature can be seen in a video (including interactively) called The Mother of a Demos. See below.

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Charles P. Thacker, an electrical engineer who played an early, central role in some of the most important ideas in personal computing and computer networking, died on Monday at his home in Palo Alto, Calif. He was 74.

His daughter Christine Thacker said the cause was complications of esophageal cancer.

In the 1970s, Mr. Thacker was part of a group that designed the first modern personal computer, the Alto, working out of the Xerox Palo Alto Research Center, known as PARC.

More here (obit.): https://goo.gl/ZZ4TtV

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In this short one-minute commercial, Xerox introduces its vision for the office of the future. Years ahead of its time, the 1972 Xerox Alto featured Ethernet networking, a full page display, a mouse, laser printing, e-mail, and a windows-based user interface. Although it's high price limited sales, the Alto was a groundbreaking invention and the inspiration for the Apple Macintosh and Microsoft Windows operating systems.

Video (YT ~1min): https://goo.gl/AkxJp6

The Xerox Alto and Charles Thacker's engineering were in part inspired by the earlier 1968 demo of the NLS by Douglas Engelbart.

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The Alto was conceived in 1972 in a memo written by Butler Lampson, inspired by the oN-Line System (NLS) developed by Douglas Engelbart, and Dustin Lindberg at SRI International (SRI). It was designed mostly by Charles P. Thacker. Industrial Design and manufacturing was sub-contracted to Xerox, whose Special Programs Group team included Doug Stewart as Program Manager, Abbey Silverstone Operations, Bob Nishimura, Industrial Designer. An initial run of 30 units was produced by Xerox El Segundo (Special Programs Group), working with John Ellenby at PARC and Doug Stewart and Abbey Silverstone at El Segundo, who were responsible for re-designing the Alto's electronics. Due to the success of the pilot run, the team went on to produce approximately 2,000 units over the next ten years.

Xerox Alto (Wikip): https://goo.gl/WKdyPS

Talking of Douglas Engelbart and the inspirational NLS...

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On December 9th, 1968 Doug Engelbart appeared on stage at the Fall Joint Computer Conference in San Francisco to give his slated presentation, titled "A Research Center for Augmenting Human Intellect." He and his team spent the next 90 minutes not only telling about their work, but demonstrating it live to a spellbound audience that filled the hall.

Instead of standing at a podium, Doug was seated at a custom designed console, where he drove the presentation through their NLS computer residing 30 miles away in his research lab at Stanford Research Institute (SRI), onto a large projection screen overhead, flipping seamlessly between his presentation outline and live demo of features, while members of his research lab video teleconferenced in from SRI in shared screen mode to demonstrate more of the system.

More here: https://goo.gl/FNUWxP

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Video: The Mother of All Demos (Internet Archive): https://goo.gl/JWH1Mf

Image: https://goo.gl/2skVz1
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Charles Thacker 1943/02/26 โ 2017/06/12

The pioneering personal computer designer Charles Thacker, a co-inventor of Ethernet, has died at the age of 74 in nearby Palo Alto. In 1972, just like personal computers of today, his Xerox Alta did not require a remote serial monitor since its tilt and swivel portrait screen was mapped directly to its hardware internals, it boasted a GUI supported directly by its OS, a three button mouse, and a detachable keyboard.

Charles Thacker based some, but not all, of the features of the Xerox Alta, on a computer system developed by Douglas Engelbart and demonstrated in 1968. These feature can be seen in a video (including interactively) called The Mother of a Demos. See below.

๐๐ผ
Charles P. Thacker, an electrical engineer who played an early, central role in some of the most important ideas in personal computing and computer networking, died on Monday at his home in Palo Alto, Calif. He was 74.

His daughter Christine Thacker said the cause was complications of esophageal cancer.

In the 1970s, Mr. Thacker was part of a group that designed the first modern personal computer, the Alto, working out of the Xerox Palo Alto Research Center, known as PARC.

More here (obit.): https://goo.gl/ZZ4TtV

๐ฌ
In this short one-minute commercial, Xerox introduces its vision for the office of the future. Years ahead of its time, the 1972 Xerox Alto featured Ethernet networking, a full page display, a mouse, laser printing, e-mail, and a windows-based user interface. Although it's high price limited sales, the Alto was a groundbreaking invention and the inspiration for the Apple Macintosh and Microsoft Windows operating systems.

Video (YT ~1min): https://goo.gl/AkxJp6

The Xerox Alto and Charles Thacker's engineering were in part inspired by the earlier 1968 demo of the NLS by Douglas Engelbart.

๐๐
The Alto was conceived in 1972 in a memo written by Butler Lampson, inspired by the oN-Line System (NLS) developed by Douglas Engelbart, and Dustin Lindberg at SRI International (SRI). It was designed mostly by Charles P. Thacker. Industrial Design and manufacturing was sub-contracted to Xerox, whose Special Programs Group team included Doug Stewart as Program Manager, Abbey Silverstone Operations, Bob Nishimura, Industrial Designer. An initial run of 30 units was produced by Xerox El Segundo (Special Programs Group), working with John Ellenby at PARC and Doug Stewart and Abbey Silverstone at El Segundo, who were responsible for re-designing the Alto's electronics. Due to the success of the pilot run, the team went on to produce approximately 2,000 units over the next ten years.

Xerox Alto (Wikip): https://goo.gl/WKdyPS

Talking of Douglas Engelbart and the inspirational NLS...

๐๐๐ฌ
On December 9th, 1968 Doug Engelbart appeared on stage at the Fall Joint Computer Conference in San Francisco to give his slated presentation, titled "A Research Center for Augmenting Human Intellect." He and his team spent the next 90 minutes not only telling about their work, but demonstrating it live to a spellbound audience that filled the hall.

Instead of standing at a podium, Doug was seated at a custom designed console, where he drove the presentation through their NLS computer residing 30 miles away in his research lab at Stanford Research Institute (SRI), onto a large projection screen overhead, flipping seamlessly between his presentation outline and live demo of features, while members of his research lab video teleconferenced in from SRI in shared screen mode to demonstrate more of the system.

More here: https://goo.gl/FNUWxP

๐ฌ
Video: The Mother of All Demos (Internet Archive): https://goo.gl/JWH1Mf

Image: https://goo.gl/2skVz1
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Daphnis

Daphnis, the wavemaker moon, an inner satellite of Saturn, has its orbit in one of the gaps in the rings of Saturn called the Keeler Gap. In fact Daphnis helps keep the Keeler gap clear, as it and its gravity, sweep through like a broom creating leading and following waves on the inner and outer edges respectively, of the A ring adjacent to the Keeler gap. Since its orbit is slightly inclined to the rings, however, some of the displaced material moves perpendicular to them creating a series of up to ~1500 metre (~1 mile) high spires (https://goo.gl/nwoZ9S and https://goo.gl/0U9utk) along the wavy edge that Daphnis creates. These however, pale in comparison to the vertical structures in the Cassini Division between the B and A rings which may be as high as ~2500 metres (~1.6 miles) high (https://goo.gl/DqJ4aV and https://goo.gl/6zKmDh).

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Daphnis (5 miles or 8 kilometers across) orbits within the 42-kilometer (26-mile) wide Keeler Gap. Cassini's viewing angle causes the gap to appear narrower than it actually is, due to foreshortening.

More here: https://goo.gl/TIi4jQ

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Daphnis orbits within the Keeler gap in Saturn's rings. As it orbits, it creates gravitational ripples on the edges of the gap as ring particles are attracted toward the moon and then fall back down toward the ring. The waves made by the moon in the inner edge of the gap precede it in orbit, while those on the outer edge lag behind it, due to the differences in relative orbital speed. In a photograph taken on January 18, 2017, a tendril of ring particles can be seen to extend toward the moon; according to JPL, "this may have resulted from a moment when Daphnis drew a packet of material out of the ring, and now that packet is spreading itself out.

Daphnis (Wikip): https://goo.gl/voP5sJ

This image is but one of the spectacular images in a series published by The Atlantic to mark the end of the Cassini mission in September.

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This September, NASAโs Cassini spacecraft will take its final measurements and images as it plunges into Saturnโs atmosphere at 77,000 miles per hour, burning up high above the cloud tops. Launched in 1997, Cassini traveled 2.2 billion miles in seven years to reach Saturn and enter orbit. Over the past 13 years, Cassiniโs instruments have returned countless priceless scientific observations and hundreds of thousands of images of the Saturnian systemโits atmosphere, its 60+ moons, its vast rings, and much more. Gathered here are 40 of the most amazing images sent to us from Cassini, as we prepare for this epic mission to come to an end in just a few months.

More here (article): https://goo.gl/JmQEcr

Image originally by JPL/NASA can be found in the article immediately above.
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Cheap eBook

For US Amazon/Kindle users there is an opportunity today to get 's I Contain Multitudes on the cheap.
You can get 's ebook, I Contain Multitudes, for only \$1.99 today. That's a great deal for a great book! (this price may be US only :( )
http://amzn.to/2s8AwGx
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Hercules Beetle

The Hercules Beetle (Dynastes hercules) lives up to its name by growing very large and especially long in the male form and becomes strong enough to carry 100 (or 100s of) times its not insignificant body mass.

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As adults, the males grow to about 78 mm in length (3 inches), but there are reports of far bigger specimens on the island of Guadeloupe in the Caribbean, which can reach between 170 and 180 mm long (roughly 7 inches).

More here (article): https://goo.gl/rq3gEY

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Timelapse video (YT ~2 mins.): https://goo.gl/XeRCOZ

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The larva of the Hercules beetle feeds on rotting wood during its two-year larval stage. The adult Hercules beetle feeds on fresh and rotting fruit. They have been observed feeding on peach, pear, apple, and grape in captivity.

More here (Wikip): https://goo.gl/TTLlpK

Related post: https://goo.gl/vKQs5p
Rhinoceros Beetle

Image: by Novita Estiti https://goo.gl/lpxW1M
See also: https://goo.gl/AOBGQQ
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Pavlov's Dogs Science Stories

In the first episode of Series 5 of Science Stories from BBC Radio 4, Naomi Alderman explains and explores the real story of Nobel Laureate, Ivan Pavlov and his dogs. It seems that it might be very different from what we have been conditioned to think. It is likely that a mistranslation from the original Russian text led to 'conditioned response' rather than 'conditional response' being recorded in English as the intent of his work. Naomi contends that in reality his work did not involve bells and automatic reactions, but was about cleverly finding a way of measuring the existence, duration and intensity of thought itself, by carefully measuring saliva in dogs as a proxy.

Perhaps Pavlov should have been given the No Bell Prize in 1904.

Say Pavlov and most people think of bells ringing and dogs salivating. Ivan Pavlov is firmly associated in many people's minds with the idea that animals and, to some extent humans, automatically respond to certain stimuli. Internal thought processes are over-rated. But, as Naomi Alderman's story of selectively drooling dogs reveals, our Pavlovian response to Pavlov himself, is often wrong. For starters, he never used bells. Using metronomes and harmoniums, he noticed that dogs could distinguish between beats played at different speeds and identify individual notes from an A minor chord. He trained dogs to recognize precise time intervals: to expect food in precisely half an hour, for example. He wanted to understand how dogs learn and treated the brain as a black box because he had no way of getting inside it. He analysed what he could, principally the arrival of saliva; but he never thought free will was an illusion. In fact, he said "it would be stupid to reject the subjective world".

Listen here (stream, download MP3, podcast): https://goo.gl/kHBL9d

Ivan Pavlov (Wikip): https://goo.gl/i4dGcb

Image: PD https://goo.gl/0TjNB1
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Baron Caterpillar
via u/spicedpumpkins

This picture was identified as a Common Baron Caterpillar (Euthalia aconthea gurda) taken in Kuala Lumpur, Malaysia, on one of its favourite foods, a mango leaf. The Baron Caterpillar is a master of camouflage!

The 5th instar caterpillar is medium green, and the yellowish-white dorsal stripe loses the earlier purple-brown spots along the edge of the stripe. The branched spines appear almost like a bird's feather, with the secondary spines arranged neatly perpendicular to the main spine. It reaches a mature length of about 45mm before shortening and adopting its pre-pupation pose.

More here: https://goo.gl/t0Rgxc

Baron Caterpillar seen from another angle: https://goo.gl/pNX9Ng

Image: by Wohin Auswandern https://goo.gl/uob8dQ
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