Friday, June 30, 2017

Sharpest Laser in the World

A Laser with a Linewidth of only 10mHz
By Erika Schow

June 29, 2017 -- No one had ever come so close to the ideal laser before: theoretically, laser light has only one single color (also frequency or wavelength). In reality, however, there is always a certain linewidth. With a linewidth of only 10 mHz, the laser that researchers from the Physikalisch-Technische Bundesanstalt (PTB) have now developed together with US researchers from JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado, Boulder, has established a new world record. This precision is useful for various applications such as optical atomic clocks, precision spectroscopy, radioastronomy and for testing the theory of relativity. The results have been published in the current issue of "Physical Review Letters".

Lasers were once deemed a solution without problems – but that is now history. More than 50 years have passed since the first technical realization of the laser, and we cannot imagine how we could live without them today. Laser light is used in numerous applications in industry, medicine and information technologies. Lasers have brought about a real revolution in many fields of research and in metrology – or even made some new fields possible in the first place.

One of a laser's outstanding properties is the excellent coherence of the emitted light. For researchers, this is a measure for the light wave's regular frequency and linewidth. Ideally, laser light has only one fixed wavelength (or frequency). In practice, the spectrum of most types of lasers can, however, reach from a few kHz to a few MHz in width, which is not good enough for numerous experiments requiring high precision.

Research has therefore focused on developing ever better lasers with greater frequency stability and a narrower linewidth. Within the scope of a nearly 10-year-long joint project with the US colleagues from JILA in Boulder, Colorado, a laser has now been developed at PTB whose linewidth is only 10 mHz (0.01 Hz), hereby establishing a new world record. "The smaller the linewidth of the laser, the more accurate the measurement of the atom's frequency in an optical clock. This new laser will enable us to decisively improve the quality of our clocks", PTB physicist Thomas Legero explains.

In addition to the new laser’s extremely small linewidth, Legero and his colleagues found out by means of measurements that the emitted laser light's frequency was more precise than what had ever been achieved before. Although the light wave oscillates approx. 200 trillion times per second, it only gets out of sync after 11 seconds. By then, the perfect wave train emitted has already attained a length of approx. 3.3 million kilometers. This length corresponds to nearly ten times the distance between the Earth and the moon.

Since there was no other comparably precise laser in the world, the scientists working on this collaboration had to set up two such laser systems straight off. Only by comparing these two lasers was it possible to prove the outstanding properties of the emitted light.

The core piece of each of the lasers is a 21-cm long Fabry-Pérot silicon resonator. The resonator consists of two highly reflecting mirrors which are located opposite each other and are kept at a fixed distance by means of a double cone. Similar to an organ pipe, the resonator length determines the frequency of the wave which begins to oscillate, i.e., the light wave inside the resonator. Special stabilization electronics ensure that the light frequency of the laser constantly follows the natural frequency of the resonator. The laser’s frequency stability – and thus its linewidth – then depends only on the length stability of the Fabry-Pérot resonator.

The scientists at PTB had to isolate the resonator nearly perfectly from all environmental influences which might change its length. Among these influences are temperature and pressure variations, but also external mechanical perturbations due to seismic waves or sound. They have attained such perfection in doing so that the only influence left was the thermal motion of the atoms in the resonator. This "thermal noise" corresponds to the Brownian motion in all materials at a finite temperature, and it represents a fundamental limit to the length stability of a solid. Its extent depends on the materials used to build the resonator as well as on the resonator's temperature.

For this reason, the scientists of this collaboration manufactured the resonator from single-crystal silicon which was cooled down to a temperature of -150 °C. The thermal noise of the silicon body is so low that the length fluctuations observed only originate from the thermal noise of the dielectric SiO2/Ta2O5 mirror layers. Although the mirror layers are only a few micrometers thick, they dominate the resonator's length stability. In total, the resonator length, however, only fluctuates in the range of 10 attometers. This length corresponds to no more than a ten-millionth of the diameter of a hydrogen atom. The resulting frequency variations of the laser therefore amount to less than 4 × 10–17 of the laser frequency.

The new lasers are now being used both at PTB and at JILA in Boulder to further improve the quality of optical atomic clocks and to carry out new precision measurements on ultracold atoms. At PTB, the ultrastable light from these lasers is already being distributed via optical waveguides and is then used by the optical clocks in Braunschweig.

"In the future, it is planned to disseminate this light also within a European network. This plan would allow even more precise comparisons between the optical clocks in Braunschweig and the clocks of our European colleagues in Paris and London", Legero says. In Boulder, a similar plan is in place to distribute the laser across a fiber network that connects between JILA and various NIST labs.

The scientists from this collaboration see further optimization possibilities. With novel crystalline mirror layers and lower temperatures, the disturbing thermal noise can be further reduced. The linewidth could then even become smaller than 1 mHz.

Thursday, June 29, 2017

Haploid Human Stem Cells

First Haploid Human Stem Cells Could Change the Face of Medical Research
Potential for regenerative medicine and cancer research earns doctoral student Ido Sagi a Kaye Innovation Award

June 28, 2017 -- Stem cell research holds huge potential for medicine and human health. In particular, human embryonic stem cells (ESCs), with their ability to turn into any cell in the human body, are essential to the future prevention and treatment of disease.

One set or two? Diploid versus haploid cells

Most of the cells in our body are diploid, which means they carry two sets of chromosomes — one from each parent. Until now, scientists have only succeeded in creating haploid embryonic stem cells — which contain a single set of chromosomes — in non-human mammals such as mice, rats and monkeys. However, scientists have long sought to isolate and replicate these haploid ESCs in humans, which would allow them to work with one set of human chromosomes as opposed to a mixture from both parents.

This milestone was finally reached when Ido Sagi, working as a PhD student at the Hebrew University of Jerusalem’s Azrieli Center for Stem Cells and Genetic Research, led research that yielded the first successful isolation and maintenance of haploid embryonic stem cells in humans. Unlike in mice, these haploid stem cells were able to differentiate into many other cell types, such as brain, heart and pancreas, while retaining a single set of chromosomes.

With Prof. Nissim Benvenisty, Director of the Azrieli Center, Sagi showed that this new human stem cell type will play an important role in human genetic and medical research. It will aid our understanding of human development – for example, why we reproduce sexually instead of from a single parent. It will make genetic screening easier and more precise, by allowing the examination of single sets of chromosomes. And it is already enabling the study of resistance to chemotherapy drugs, with implications for cancer therapy.

Diagnostic kits for personalized medicine

Based on this research, Yissum, the Technology Transfer arm of the Hebrew University, launched the company New Stem, which is developing a diagnostic kit for predicting resistance to chemotherapy treatments. By amassing a broad library of human pluripotent stem cells with different mutations and genetic makeups, NewStem plans to develop diagnostic kits for personalized medication and future therapeutic and reproductive products.

Wednesday, June 28, 2017

Binary Black Holes Studied

Astronomers Detect Orbital Motion
in Pair of Supermassive Black Holes
VLBA reveals first-ever black-hole "visual binary"

Using the supersharp radio “vision” of the National Science Foundation’s Very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of upermassive black holes in a galaxy some 750 million light-years from Earth.

The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.

“This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole ‘visual binary,'” said Greg Taylor, of the University of New Mexico (UNM).

Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.

“We believe that the two supermassive black holes in this galaxy will merge,” said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future.

The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.

The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists’ initial calculations indicate that they complete a single orbit in about 30,000 years.

“We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of the black holes,” Taylor said. “This pair of black holes offers us our first chance to study how such systems interact,” he added.

The astronomers also hope to discover other such systems. The galaxy mergers that bring two supermassive black holes close together are considered to be a common process in the universe, so astronomers expect that such binary pairs should be common.

“Now that we’ve been able to measure orbital motion in one such pair, we’re encouraged to seek other, similar pairs. We may find others that are easier to study,” Bansal said.

The VLBA, part of the Long Baseline Observatory, is a continent-wide radio telescope system using ten, 240-ton dish antennas distributed from Hawaii to St. Croix in the Caribbean. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. That extraordinary resolving power allows scientists to make extremely fine measurements of objects and motions in the sky, such as those done for the research on 0402+379.

Tuesday, June 27, 2017

Yemen's Cholera Outbreak

In October 2016, an outbreak of cholera began in Yemen. By mid-March 2017, the outbreak was in decline, but it has resurged since 27 April 2017 – reportedly after the sewer system in the capital of Sana'a ceased functioning – and remains ongoing as of June 2017.

Course of the Outbreak

The cholera outbreak began in early October 2016. The World Health Organization (WHO) considers the outbreak to be unusual in its rapid and wide geographical spread. The earliest cases were predominantly in the capital, Sana'a, with some occurring on the northern coast. By the end of October, cases had been reported in the governorates of Al-Bayda, Aden, Al-Hudaydah, Hajjah, Ibb, Lahij and Taiz and, by late November, also in Al-Dhale'a and Amran. By mid-December, 135 districts of 15 governorates had reported suspected cases, but nearly two-thirds were confined to Aden, Al-Bayda, Al-Hudaydah and Taiz. By mid-January of the following year, 80% of cases were located in 28 districts of Al-Dhale'a, Al-Hudaydah, Hajjah, Lahij and Taiz.

By the end of February 2017, the rate of spread in most areas had reduced, and by mid-March 2017, the outbreak was in decline. A total of 25,827 suspected cases, including 129 deaths, had been reported by 26 April 2017.

The number of cholera cases resurged after 27 April 2017. During May, 74,311 suspected cases, including 605 deaths, were reported. By 24 June 2017, UNICEF and WHO estimated that the total number of cases in the country since the outbreak began in October had exceeded 200,000, with 1,300 deaths, and that 5,000 new cases a day were occurring. The two agencies stated that it was then "the worst cholera outbreak in the world". Approximately half of the cases, and a quarter of the deaths were among children.

As of 12 June 2017, the case fatality rate for the outbreak is 0.7%, with higher rates in people over 60 years old (3.2%). The serotype of Vibrio cholerae involved is Ougawa. A total of 268 districts from 20 of the country's 23 governorates had reported cases by 21 June 2017; over half are from the governorates of Amanat Al Asimah (the capital Sana'a), Al Hudeideh, Amran and Hajjah, which are all located in the west of the country.

WHO, UNICEF, the International Committee of the Red Cross (ICRC) and Médecins Sans Frontières are among the organisations providing assistance.

Related Factors

UNICEF and WHO attributed the outbreak to malnutrition and collapsing sanitation and clean water systems due to the country's ongoing conflict. An ICRC worker in Yemen noted that April's cholera resurgence began ten days after Sana'a's sewer system stopped working. The impacts of the outbreak have been reported to have been exacerbated by the collapse of the Yemeni health services, where many health workers have remained unpaid for months. The International Committee of the Red Cross (ICRC) and the UN, have pointed to the Saudi-led naval and aerial blockade and bombing campaign as central causes behind the preventable cholera epidemic.

"With the right medicines, these [diseases] are all completely treatable – but the Saudi Arabia-led coalition is stopping them from getting in."

— Grant Pritchard, Save the Children's interim country director for Yemen, April 2017, Vice News

https://en.wikipedia.org/wiki/2016%E2%80%9317_Yemen_cholera_outbreak

Monday, June 26, 2017

Selfish Yet Humane Heroics

Putting Others First Can
Cost Lives in Emergencies

Waterloo, Ontario – June 23, 2017 -- Selfless heroism isn’t the best strategy in life-and-death disaster situations involving groups of people, a new study from the University of Waterloo suggests.

The study, which used computer modeling of a flooded subway station, found overall survival rates were substantially higher when strong people in a 30-member group reached safety themselves before trying to help weaker people.

“Foolhardiness is not a good strategy for rescuing,” said Eishiro Higo, a civil engineering PhD candidate at Waterloo who led the research. “In very critical situations, we have to be kind of selfish, but we can still help others if we have proper equipment and proper strategies.”

In effect, he said, the study showed that when strong members try to help weak members before they are secure themselves, both are dragged down and the group as a whole suffers.

Higo and colleagues built a two-dimensional computer model of an actual three-level underground space in Kyoto, Japan that consists of a subway platform, a parking garage and a shopping mall.

The model simulates severe flooding from a nearby river, with a mix of adults and senior citizens who must reach safety via staircases from the subway platform level to the surface.

Higo repeatedly ran the model using three different evacuation strategies: one in which people only worried about themselves; one in which people immediately worked together as a group; and one in which those capable of saving themselves reached a safe place before trying to save others using a rope.

In most life-and-death scenarios when variables such as the ratio of adults to seniors were adjusted, the rope strategy resulted in the highest overall survival rate.

In a typical scenario that assumed evacuation efforts beginning at a particular point in time, for example, 12 of 30 people survived using the rope strategy, while there were just five survivors using either of the other two strategies.

“We have to identify what is brave and what is reckless,” said Higo. “Helping people from a safe location is still good behaviour and the result is actually much better.”

Crucial to the success of the rope strategy, however, was the availability of simple tools for use by rescuers. Design features including handrails and raised areas on stairs for evacuees to brace themselves or rest also markedly increased the chances of survival.

An extension of work he did for his master’s degree at Kyoto University before coming to Waterloo, his research was motivated in large part by the earthquake and tsunami that devastated east Japan in 2011.

Higo hopes his findings stimulate discussion and lead to the inclusion of relatively inexpensive disaster preparedness features such as ropes and resting areas in public spaces.

Details of the research were recently published in the journal Expert Systems with Applications.

Sunday, June 25, 2017

Pakistani Tanker Truck Explosion

On 25 June 2017, a tank truck exploded near Ahmedpur East in Pakistan's Bahawalpur District [south-central Punjab of Pakistan], killing at least 153 people and injuring more than 117 others. The truck overturned when its driver attempted to make a sharp turn on the N-5 National Highway. Once the news of the accident spread to nearby villages, hundreds of residents rushed to the scene to loot the truck of its fuel cargo. The explosion is believed to have been caused when someone lit a cigarette.

Accident

Around 06:00 local time (01:00 GMT), a tank truck carrying 40,000 litres (10,567 gallons) of fuel overturned as its tires burst while trying to make a sharp turn on N-5 National Highway near Ahmedpur East, Bahawalpur District, in Punjab, Pakistan. The truck was travelling from Karachi to Lahore.

The news of the accident quickly spread to the nearby village of Ramzanpur Joya, with villagers being alerted via a loudspeaker on top of a local mosque. A large number of people busy working in mango farms beside the road (one source estimated about 500), including women and children, subsequently gathered at the site to collect leaking petrol. The crowd ignored attempts by police to clear the area. About 10 minutes later, the truck exploded after leaked fuel from its damaged container caught fire killing at least 153 people and injuring more than 117 others. According to some media reports, the explosion occurred about 45 minutes after the initial truck crash.

Preliminary information indicates that the explosion resulted when someone tried to light a cigarette near the overturned tanker. It is also believed that a spark from the numerous cars and motorcycles that rushed to the scene ignited the fuel

Response

The motorway police suspended the traffic and set up two diversions, near Noorpur Nauranga and further ahead of Dera Nawaz. The Rescue 1122 and fire brigade arrived on the site of the incident immediately after the blaze started and rescue operations were initiated. Firefighters fought the blaze for over two hours before extinguishing the fire.

At least 90 of the victims were taken to District Headquarters Hospital and Bahawal Victoria Hospital in Bahawalpur. Pakistan Army helicopters were used to transfer 51 injured people from Bahawalpur to Nishtar Hospital in Multan.

Aftermath

Most bodies were burned beyond recognition, many down to their skeletons. At least six cars and 12 motorcycles were burnt in the explosion. The highway was littered with kitchen utensils, pots, water coolers, jerrycans and buckets of the victims. The driver of the fuel tanker survived the crash and was taken into custody.

Similar Catastrophic Events




Link for the article above regarding the Punjab incident: https://en.wikipedia.org/wiki/2017_Bahawalpur_explosion

Saturday, June 24, 2017

Possible Uses for Graphene

Potential graphene applications include lightweight, thin, flexible, yet durable display screens, electric/photonics circuits, solar cells, and various medical, chemical and industrial processes enhanced or enabled by the use of new graphene materials.

In 2008, graphene produced by exfoliation was one of the most expensive materials on Earth, with a sample the area of a cross section of a human hair costing more than $1,000 as of April 2008 (about $100,000,000/cm2). Since then, exfoliation procedures have been scaled up, and now companies sell graphene in large quantities. The price of epitaxial graphene on Silicon carbide is dominated by the substrate price, which was approximately $100/cm2 as of 2009. Hong and his team in South Korea pioneered the synthesis of large-scale graphene films using chemical vapour deposition (CVD) on thin nickel layers, which triggered research on practical applications, with wafer sizes up to 30 inches (760 mm) reported.

In 2013, the European Union made a €1 billion grant to be used for research into potential graphene applications. In 2013 the Graphene Flagship consortium formed, including Chalmers University of Technology and seven other European universities and research centers, along with Nokia.

Potential Applications Under Study

·         Medicine, including tissue engineering, contrast agents and bioimaging, polymerase chain reaction, devices, drug delivery, biomicrorobotics, testing, and toxicity

·         Electronics, including transistors, transparent conducting electrodes, frequency multipliers, optoelectronics, Hall effect sensors, quantum dots, organic electronics, spintronics, and conductive ink

·         Light processing, including optical modular, ultraviolet lens, infrared light detection, and photodetector

  • Energy, including generation and storage
 
  • Sensors, including pressure sensors, NEMS, molecular adsorbtion, piezoelectric effect, body motion and magnetic
 
  • Environmental, including contaminant removal and water filtration
 
  • Other, such as plasmonics and metamaterials, lubricant, radio wave absorption, redox, nanoantennas, sound transducers, waterproof coating, coolant additive, reference material, thermal management, structural material, catalyst, and aviation

Detailed discussion at:

Friday, June 23, 2017

The Trumpet and its Masters

A trumpet is a blown musical instrument commonly used in classical and jazz ensembles. The trumpet group contains the instruments with the highest register in the brass family. Trumpet-like instruments have historically been used as signaling devices in battle or hunting, with examples dating back to at least 1500 BC; they began to be used as musical instruments only in the late 14th or early 15th century. Trumpets are used in art music styles, for instance in orchestras, concert bands, and jazz ensembles, as well as in popular music. They are played by blowing air through almost-closed lips (called the player's embouchure), producing a "buzzing" sound that starts a standing wave vibration in the air column inside the instrument. Since the late 15th century they have primarily been constructed of brass tubing, usually bent twice into a rounded rectangular shape.

There are many distinct types of trumpet, with the most common being pitched in B (a transposing instrument), having a tubing length of about 1.48 m (4 ft 10 in). Early trumpets did not provide means to change the length of tubing, whereas modern instruments generally have three (or sometimes four) valves in order to change their pitch. Most trumpets have valves of the piston type, while some have the rotary type. The use of rotary-valved trumpets is more common in orchestral settings, although this practice varies by country. Each valve, when engaged, increases the length of tubing, lowering the pitch of the instrument. A musician who plays the trumpet is called a trumpet player or trumpeter.

Masterful Trumpet Players

In early jazz, Louis Armstrong was well known for his virtuosity and his improvisations on the Hot Five and Hot Seven recordings. Miles Davis is widely considered one of the most influential musicians of the 20th century—his style was distinctive and widely imitated. Davis' phrasing and sense of space in his solos have been models for generations of jazz musicians. Dizzy Gillespie was a gifted improviser with an extremely high (but musical) range, building on the style of Roy Eldridge but adding new layers of harmonic complexity. Gillespie had an enormous impact on virtually every subsequent trumpeter, both by the example of his playing and as a mentor to younger musicians. Maynard Ferguson came to prominence playing in Stan Kenton's orchestra, before forming his own band in 1957. He was noted for being able to play accurately in a remarkably high register.

Some other notable jazz/commercial trumpet players include James Morrison, Roy Eldridge, Nat Adderley, Bud Brisbois, Randy Brecker, Chet Baker, Clifford Brown, Chris Botti, Allan Botschinsky, Donald Byrd, Bill Chase, Doc Cheatham, Don Cherry, Kenny Dorham, Dave Douglas, Don Ellis, Ziggy Elman, Jon Faddis, Thomas Gansch, Tim Hagans, Roy Hargrove, Tom Harrell, Erskine Hawkins, Al Hirt, Freddie Hubbard, Roger Ingram, Harry James, Ibrahim Maalouf, Chuck Mangione, Wynton Marsalis, Billy May, Blue Mitchell, Lee Morgan, Fats Navarro, Nicholas Payton, Louis Prima, Uan Rasey, Claudio Roditi, Wallace Roney, Arturo Sandoval, Manfred Schoof, Bobby Shew, Dale Turner, Doc Severinsen, Woody Shaw, Tomasz Stańko, Markus Stockhausen, Clark Terry, Wayne Bergeron, Allen Vizzutti, Cootie Williams, and Snooky Young.

Notable classical trumpeters include Maurice André, Armando Ghitalla, Alison Balsom, Hakan Hardenberger, Tine Thing Helseth, Adolph "Bud" Herseth, Malcolm McNab, Rafael Méndez, Maurice Murphy, Sergei Nakariakov, Uan Rasey, Charles Schlueter, Philip Smith, William Vacchiano, Allen Vizzutti, and Roger Voisin.

Notable natural trumpet players include Valentine Snow, for whom Handel wrote several pieces, and Gottfried Reiche, who was Bach's chief trumpeter.

Thursday, June 22, 2017

Gold Diggers of 1933 film

Gold Diggers of 1933 is a pre-Code Warner Bros. musical film directed by Mervyn LeRoy with songs by Harry Warren (music) and Al Dubin (lyrics), staged and choreographed by Busby Berkeley. It stars Warren William, Joan Blondell, Aline MacMahon, Ruby Keeler and Dick Powell, and features Guy Kibbee, Ned Sparks and Ginger Rogers.

                                                 Ruby Keeler and Dick Powell
The story is based on the play The Gold Diggers by Avery Hopwood, which ran for 282 performances on Broadway in 1919 and 1920. The play was made into a silent film in 1923 by David Belasco, the producer of the Broadway play, as The Gold Diggers, starring Hope Hampton and Wyndham Standing, and again as a talkie in 1929, directed by Roy Del Ruth. That film, Gold Diggers of Broadway, which starred Nancy Welford and Conway Tearle, was the biggest box office hit of that year, and Gold Diggers of 1933 was one of the top-grossing films of 1933. This version of Hopwood's play was written by James Seymour and Erwin S. Gelsey, with additional dialogue by David Boehm and Ben Markson.

In 2003, Gold Diggers of 1933 was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".

Basic Plot of the Movie

The "gold diggers" are four aspiring actresses: Polly (Ruby Keeler), an ingenue; Carol (Joan Blondell), a torch singer; Trixie (Aline MacMahon), a comedian; and Fay (Ginger Rogers), a glamour puss.

The film was made in 1933, during the Great Depression and contains numerous direct references to it. It begins with a rehearsal for a stage show, which is interrupted by the producer's creditors who close down the show because of unpaid bills.

At the unglamorous apartment shared by three of the four actresses (Polly, Carol, and Trixie), the producer, Barney Hopkins (Ned Sparks), is in despair because he has everything he needs to put on a show, except money. He hears Brad Roberts (Dick Powell), the girls' neighbor and Polly's boyfriend, playing the piano. Brad is a brilliant songwriter and singer who not only has written the music for a show, but also offers Hopkins $15,000 in cash to back the production. Of course, they all think he is kidding, but he insists that he is serious – he offers to back the show, but refuses to perform in it, despite his talent and voice.

Brad comes through with the money and the show goes into production, but the girls are suspicious that he must be a criminal since he is cagey about his past and will not appear in the show, even though he is clearly more talented than the aging juvenile lead (Clarence Nordstrom) they have hired. It turns out, however, that Brad is in fact a millionaire's son whose family does not want him associating with the theatre. On opening night, in order to save the show when the juvenile cannot perform (due to his lumbago acting up), Brad is forced to play the lead role.

With the resulting publicity, Brad's brother J. Lawrence Bradford (Warren William) and family lawyer Fanuel H. Peabody (Guy Kibbee) discover what he is doing and go to New York to save him from being seduced by a "gold digger".

Lawrence mistakes Carol for Polly, and his heavy-handed effort to dissuade the "cheap and vulgar" showgirl from marrying Brad by buying her off annoys her so much that she plays along, but the two fall in love. Meanwhile, Trixie targets "Fanny" the lawyer as the perfect rich sap ripe for exploitation. When Lawrence finds out that Brad and Polly have wed, he threatens to have the marriage annulled, but relents when Carol refuses to marry him if he does. Trixie marries Fanuel. All the "gold diggers" (except Fay) end up with wealthy men.

Famous Musical Numbers

The film contains four song and dance sequences designed, staged and choreographed by Busby Berkeley. All the songs were written by Harry Warren and Al Dubin. (In the film, when producer Barney Hopkins hears Brad's music he picks up the phone and says: "Cancel my contract with Warren and Dubin!")

"We're in the Money" is sung by Ginger Rogers accompanied by scantily-clad showgirls dancing with giant coins. Rogers sings one verse in Pig Latin.  [The creditors arrive on the scene and stop the song and rehearsal.  Separately, but not part of the film, an important recording of “We’re in the Money” was a major hit for Dick Powell].

"Pettin' in the Park" is sung by Ruby Keeler and Dick Powell. It includes a tap dance from Keeler and a surreal sequence featuring dwarf actor Billy Barty as a baby who escapes from his stroller. During the number, the women get caught in a rainstorm and go behind a backlit screen to remove their wet clothes in silhouette. They emerge in metal garments, which thwart the men's attempts to remove them, until Billy Barty gives Dick Powell a can opener. This number was originally planned to end the film.

"The Shadow Waltz" is sung by Powell and Keeler. It features a dance by Keeler, Rogers, and many female violinists with neon-tubed violins that glow in the dark. Berkeley got the idea for this number from a vaudeville act he once saw - the neon on the violins was an afterthought. On March 10, the Long Beach earthquake hit while this number was being filmed:

[it] caused a blackout and short-circuited some of the dancing violins. Berkeley was almost thrown from the camera boom, dangling by one hand until he could pull himself back up. He yelled for the girls, many of whom were on a 30-foot (9.1 m)-high platform, to sit down until technicians could get the soundstage doors open and let in some light.



"Remember My Forgotten Man" is sung by Joan Blondell and Etta Moten and features sets influenced by German Expressionism and a gritty evocation of Depression-era poverty. Berkeley was inspired by the May 1932 war veterans' march on Washington, D.C. When the number was finished, Jack L. Warner and Darryl F. Zanuck (the studio production head) were so impressed that they ordered it moved to the end of the film, displacing "Pettin' in the Park".

https://en.wikipedia.org/wiki/Gold_Diggers_of_1933

Footnote by the Blog Author

In addition to the numerous memorable and catchy tunes of Warren and Dubin, this movie may be the best movie ever made about the Depression.  The singers and dancers in the chorus will be desperately out of work if the musical isn’t produced to open as a sustaining hit, according to the plot.  The pathos of the cast nervously fidgeting while waiting for a $15,000 loan to come through is a neurotic classic of filmmaking.  “The Forgotten Man” number is a profound and overdue salute to Great War veterans, a showstopper that ends the movie in the alternate version of editing.

Wednesday, June 21, 2017

"Dead Disk Galaxy" Found

Hubble Captures Massive Dead Disk Galaxy that Challenges Theories of Galaxy Evolution

NASA -- By combining the power of a "natural lens" in space with the capability of NASA's Hubble Space Telescope, astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang.

Finding such a galaxy early in the history of the universe challenges the current understanding of how massive galaxies form and evolve, say researchers.

When Hubble photographed the galaxy, astronomers expected to see a chaotic ball of stars formed through galaxies merging together. Instead, they saw evidence that the stars were born in a pancake-shaped disk.

This is the first direct observational evidence that at least some of the earliest so-called "dead" galaxies — where star formation stopped — somehow evolve from a Milky Way-shaped disk into the giant elliptical galaxies we see today.

This is a surprise because elliptical galaxies contain older stars, while spiral galaxies typically contain younger blue stars. At least some of these early "dead" disk galaxies must have gone through major makeovers. They not only changed their structure, but also the motions of their stars to make a shape of an elliptical galaxy.

"This new insight may force us to rethink the whole cosmological context of how galaxies burn out early on and evolve into local elliptical-shaped galaxies," said study leader Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute, University of Copenhagen, Denmark. "Perhaps we have been blind to the fact that early "dead" galaxies could in fact be disks, simply because we haven't been able to resolve them."

Previous studies of distant dead galaxies have assumed that their structure is similar to the local elliptical galaxies they will evolve into. Confirming this assumption in principle requires more powerful space telescopes than are currently available. However, through the phenomenon known as "gravitational lensing," a massive, foreground cluster of galaxies acts as a natural "zoom lens" in space by magnifying and stretching images of far more distant background galaxies. By joining this natural lens with the resolving power of Hubble, scientists were able to see into the center of the dead galaxy.

The remote galaxy is three times as massive as the Milky Way but only half the size. Rotational velocity measurements made with the European Southern Observatory's Very Large Telescope (VLT) showed that the disk galaxy is spinning more than twice as fast as the Milky Way.

Using archival data from the Cluster Lensing And Supernova survey with Hubble (CLASH), Toft and his team were able to determine the stellar mass, star-formation rate, and the ages of the stars.

Why this galaxy stopped forming stars is still unknown. It may be the result of an active galactic nucleus, where energy is gushing from a supermassive black hole. This energy inhibits star formation by heating the gas or expelling it from the galaxy. Or it may be the result of the cold gas streaming onto the galaxy being rapidly compressed and heated up, preventing it from cooling down into star-forming clouds in the galaxy's center.

But how do these young, massive, compact disks evolve into the elliptical galaxies we see in the present-day universe? "Probably through mergers," Toft said. "If these galaxies grow through merging with minor companions, and these minor companions come in large numbers and from all sorts of different angles onto the galaxy, this would eventually randomize the orbits of stars in the galaxies. You could also imagine major mergers. This would definitely also destroy the ordered motion of the stars."

The findings are published in the June 22 issue of the journal Nature. Toft and his team hope to use NASA's upcoming James Webb Space Telescope to look for a larger sample of such galaxies.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

The Very Large Telescope is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of Northern Chile.

Tuesday, June 20, 2017

HIV Vaccine Is Studied

San Diego Team Tests Best Delivery
Mode for Potential HIV Vaccine
Optimized immunizations reliably elicit protective antibodies in preclinical study, marking an important milestone on the way to an effective HIV vaccine.

LA JOLLA, CA -- June 20, 2017 —For decades, HIV has successfully evaded all efforts to create an effective vaccine but researchers at The Scripps Research Institute (TSRI) and the La Jolla Institute for Allergy and Immunology (LJI) are steadily inching closer. Their latest study, published in the current issue of Immunity, demonstrates that optimizing the mode and timing of vaccine delivery is crucial to inducing a protective immune response in a preclinical model.

More than any other factors, administering the vaccine candidate subcutaneously and increasing the time intervals between immunizations improved the efficacy of the experimental vaccine and reliably induced neutralizing antibodies. Neutralizing antibodies are a key component of an effective immune response. They latch onto and inactive invading viruses before they can gain a foothold in the body and have been notoriously difficult to generate for HIV.

“This study is an important staging point on the long journey toward an HIV vaccine,” says TSRI Professor Dennis R. Burton, Ph.D, who is also scientific director of the International AIDS Vaccine Initiative (IAVI) Neutralizing Antibody Center and of the National Institutes of Health’s Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery (CHAVI-ID) at TSRI. “The vaccine candidates we worked with here are probably the most promising prototypes out there, and one will go into people in 2018,” says Burton.

“There had been a lot of big question marks and this study was designed to get as many answers as possible before we go into human clinical trials,” adds senior co-author Shane Crotty, Ph.D., a professor in LJI’s Division of Vaccine Discovery. “We are confident that our results will be predictive going forward.”

HIV has faded from the headlines, mainly because the development of antiretroviral drugs has turned AIDS into a chronic, manageable disease. Yet, only about half of the roughly 36.7 million people currently infected with HIV worldwide are able to get the medicines they need to control the virus.

At the same time, the rate of new infections has remained stubbornly high, emphasizing the need for a preventive vaccine.

The latest findings are the culmination of years of collaborative and painstaking research by a dozen research teams centered around the development, improvement, and study of artificial protein trimers that faithfully mimic a protein spike found on the viral surface. At the core of this effort is the CHAVI-ID immunogen working group, comprised of TSRI’s own William R. Schief, Ph.D., Andrew B. Ward, Ph.D., Ian A. Wilson, D.Phil. and Richard T. Wyatt, Ph.D., in addition to Crotty and Burton. This group of laboratories in collaboration with Darrell J. Irvine, Ph.D., professor at MIT, and Rogier W. Sanders, Ph.D., professor at the University of Amsterdam, provided the cutting-edge immunogens tested in the study.

The recombinant trimers, or SOSIPs as they are called, were unreliable in earlier, smaller studies conducted in non-human primates. Non-human primates, and especially rhesus macaques, are considered the most appropriate pre-clinical model for HIV vaccine studies, because their immune system most closely resembles that of humans.

“The animals’ immune responses, although the right kind, weren’t very robust and a few didn’t respond at all,” explains Colin Havenar-Daughton, Ph.D., a scientific associate in the Crotty lab. “That caused significant concern that the immunogen wouldn’t consistently trigger an effective immune response in all individuals in a human clinical trial.”

In an effort to reliably induce a neutralizing antibody response, the collaborators tested multiple variations of the trimers and immunization protocols side-by-side to determine the best strategy going forward. Crotty and Burton and their colleagues teamed up with Professor Dan Barouch, M.D., Ph.D., Director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, who coordinated the immunizations.

The design of the study was largely guided by what the collaborators had learned in a previous study via fine needling sampling of the lymph nodes, where the scientists observed follicular helper T cells help direct the maturation steps of antibody-producing B cells. Administering the vaccine subcutaneously versus the more conventional intramuscular route, and spacing the injection at 8 weeks instead of the more common 4-6 weeks, reliably induced a strong functional immune response in all animals.

Using an osmotic pump to slowly release the vaccine over a period of two weeks resulted in the highest neutralizing antibody titers ever measured following SOSIP immunizations in non-human primates. While osmotic pumps are not a practical way to deliver vaccines, they illustrate an important point.

“Depending on how we gave the vaccine, there was a bigger difference due to immunization route than we would have predicted,” says Matthias Pauthner, a graduate student in Burton’s lab and the study’s co-lead author. “We can help translate what we know now into the clinic.”

Monday, June 19, 2017

Catherine Austin FItts Speaks

Catherine Austin Fitts is the president of Solari, Inc., the publisher of The Solari Report and managing member of Solari Investment Advisory Services, LLC.

Catherine Fitts is a reoccurring guest on the overnight radio program Coast to Coast AM.  [She is also seen in several YouTube videos and online interviews].

Background

Fitts served as managing director and member of the board of directors of the Wall Street investment bank Dillon, Read & Co. Inc., as Assistant Secretary of Housing and Federal Housing Commissioner at the United States Department of Housing and Urban Development in the first Bush Administration, and was the president of Hamilton Securities Group, Inc., an investment bank and financial software developer.

Fitts has a BA from the University of Pennsylvania, an MBA from the Wharton School and studied Mandarin at the Chinese University of Hong Kong.

https://en.wikipedia.org/wiki/Catherine_Austin_Fitts

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The Popsicle Index is a quality of life measurement coined by Catherine Austin Fitts as the percentage of people - in a community who believe that a child in their community can safely leave their home, walk to the nearest possible location to buy a popsicle, and walk back home.


Quotes from Fitts

“We have a group of people who have the power to act with impunity.  They are above the law.  They are centralizing and consolidating economic and political power.  We have a political problem.  We don’t have an economic problem.”  Fitts’ analysis shows, “We’ve been on a debt model, and now we’ve got to get the planet on an equity model. . . .You are going to do everything you can do to get people into equities.  Slamming precious metals down helps do that.”  But Fitts says that won’t stop the gold bull because China and the rest of the world are buying the yellow metal.  Fitts contends, “What that means is there is going to be a much more broad-based bull market in gold. . . I think it’s going to more of a sound money system, and gold is going to be a part of that.”  Not everybody wants to be brought into the so-called new world order.  Fitts predicts, “Remember, to come out with a one world currency, you need everybody.  There can be no leakage.  There can be no exceptions. The Russians are determined to be the stinker at the party is what I think.” 

Sunday, June 18, 2017

Dangerous Bird Flu Mutations

Mutations that Allow Bird Flu Strain
to Spread Among Humans Identified
Monitoring for these mutations could enable
timely response to prevent pandemic

An international team of scientists has identified several genetic mutations that, should they arise, could potentially allow the avian influenza strain H7N9 to spread between humans. The findings are published in PLOS Pathogens.

PLOS – June 15, 2017 -- H7N9 is a strain of flu virus that normally infects birds but has spread to at least 779 humans in a number of outbreaks related to poultry markets. The virus is not currently capable of spreading sustainably from human to human, but scientists are concerned that it could potentially mutate into a form that can.

To investigate this possibility, James Paulson of The Scripps Research Institute, California, and colleagues analyzed mutations that could occur in H7N9's genome. They focused on a gene that codes for the H7 hemagglutanin, a protein found on the surface of flu viruses. This protein allows flu viruses to latch onto host cells.

Flu strains that circulate in avian viruses have different subtypes of hemagglutanin, called H1-H16. So far only three subtypes have been found in human flu viruses (H1, H2 and H3). Like other avian flu viruses, H7N9 has is specific for receptors on bird cells, but not receptors on human cells. However, a transition to human specificity could enable H7N9 to circulate among humans, just like other human flu strains that have caused pandemics in the past.

The research team used molecular modeling and knowledge of hemagglutanin's structure to identify mutations that would change the protein's amino acid sequence and cause a switch to human specificity. Then, they produced the hemagglutanin with different combinations of these mutations in an experimental cell line (testing the mutations in H7N9 viruses themselves could be dangerous).

The scientists harvested the mutant hemagglutanin proteins from the cells and tested how strongly they bound to human-type and bird-type receptors. Several forms with mutations in three amino acids bound far more strongly to human receptors; they had switched specificity from bird to human. These triple-mutant H7 hemagglutinins also successfully latched onto cells in samples of human trachea tissue.

Safety regulations prohibit introducing these mutations to actual H7N9 viruses, limiting scientists' ability to test their effects in animals. Nonetheless, the research team suggests that keeping an eye out for the development of these mutations in humans infected with H7N9 could help trigger a timely response to prevent potential spread.

Saturday, June 17, 2017

Basics of Agitprop

Agitprop (portmanteau of "agitation" and "propaganda") is political propaganda, especially the communist propaganda used in Soviet Russia, that is spread to the general public through popular media such as literature, plays, pamphlets, films, and other art forms with an explicitly political message. In the Western world, agitprop often has a negative connotation.

The term originated in Soviet Russia as a shortened name for the Department for Agitation and Propaganda (отдел агитации и пропаганды, otdel agitatsii i propagandy), which was part of the central and regional committees of the Communist Party of the Soviet Union. The department was later renamed Ideological Department. Typically Russian agitprop explained the policies of the Communist Party and persuaded the general public to share its values and goals. In other contexts, propaganda could mean dissemination of any kind of beneficial knowledge, e.g., of new methods in agriculture. After the October Revolution of 1917, an agitprop train toured the country, with artists and actors performing simple plays and broadcasting propaganda. It had a printing press on board the train to allow posters to be reproduced and thrown out of the windows if it passed through villages.

It gave rise to agitprop theatre, a highly politicized left-wing theatre that originated in 1920s Europe and spread to the United States; the plays of Bertolt Brecht are a notable example. Russian agitprop theater was noted for its cardboard characters of perfect virtue and complete evil, and its coarse ridicule. Gradually the term agitprop came to describe any kind of highly politicized art.

Forms of Agitprop

During the Russian Civil War, agitprop took various forms:

  • Censorship of the press: Bolshevik strategy from the beginning was to introduce censorship over the primary medium of information in the former Russian Empire in 1917, the newspaper. The provisional government, born out of the March Revolution against the tsarist regime, abolished the age-old practice of censoring the press. This created free newspapers that survived on their own revenue. The Bolsheviks' power over the provisional government lay in the Petrograd Soviet of Workers’ and Soldiers’ Deputies, because they could shut down industry and government by calling in workers and soldiers to strike and demonstrate. This ability to orchestrate strikes was especially helpful in the newspaper printing factories because a strike would mean a large loss in revenue, and the inability to continue to operate. The capability of strikes allowed the Bolsheviks to shut down any newspaper they wanted, creating a highly effective censorship mechanism that put a stop to the voice of the opposition. Lenin took control of the socialist newspaper Pravda, making it an outlet to spread Bolshevik agitprop, articles, and other media. With the Bolshevik capability to censor and shut down newspapers of opposing or rival factions, Pravda was able to become the dominant source of written information for the population in regions controlled by the Red Army .



  • Oral-agitation networks: The Bolshevik leadership understood that to build a lasting regime, they would need to win the support of the mass population of Russian peasants. To do this, Lenin organized a Communist party that attracted demobilized soldiers and others to become indoctrinated in Bolshevik ideology, dressed up in uniforms and sent to travel the countryside as agitators to the peasants. The oral-agitation networks established a presence in the isolated rural areas of Russia, expanding Communist power.
  • Agitational trains and ships: To expand the reach of the oral-agitation networks, the Bolsheviks pioneered using modern transportation to reach deeper into Russia. The trains and ships carried agitators armed with leaflets, posters and other various forms of agitprop. The agitational trains expanded the reach of agitators into Eastern Europe, and allowed for the establishment of agitprop stations, consisting of libraries of propaganda material. The trains were also equipped with radios, and their own printing press, so they could report to Moscow the political climate of the given region, and receive instruction on how to custom print propaganda on the spot to better take advantage of the situation.
  • Literacy campaign: Lenin understood that in order to increase the effectiveness of his propaganda, the cultural level of the Russian people would have to be raised by bringing down the illiteracy rate. The peasant society of Russia in 1917 was largely illiterate making it difficult to reach them through printed agitprop. Lenin created the People’s Commissariat of Enlightenment to spearhead the war on illiteracy. Instructors were trained in 1919, and sent to the countryside to create more instructors and expand the operation into a network of illiteracy centers. New textbooks were created, containing Bolshevik ideology to indoctrinate the newly literate members of Soviet society, and the literacy training in the army was expanded.

Friday, June 16, 2017

Helmut Kohl Dies

Helmut Josef Michael Kohl (3 April 1930 – 16 June 2017) was a German politician who served as Chancellor of Germany from 1982 to 1998 (of West Germany 1982–1990 and of the reunited Germany 1990–1998) and as the chairman of the Christian Democratic Union (CDU) from 1973 to 1998. From 1969 to 1976, Kohl was Minister President of Rhineland-Palatinate.

                                                                Helmut Kohl in 1989

Kohl's 16-year tenure was the longest of any German Chancellor since Otto von Bismarck. Kohl oversaw the end of the Cold War and is widely regarded as the mastermind of German reunification. Together with French President François Mitterrand, Kohl is considered to be the architect of the Maastricht Treaty, which established the European Union (EU) and the euro currency. His life in the immediate years after his chancellorship was overshadowed by a donations scandal.

Reunification of Germany

Kohl was described as "the greatest European leader of the second half of the 20th century" by U.S. Presidents George H. W. Bush and Bill Clinton. Kohl received the Charlemagne Prize in 1988 with François Mitterrand; in 1998 Kohl became the second person to be named Honorary Citizen of Europe by the European heads of state or government.

Following the breach of the Berlin Wall and the collapse of the East German Communist regime in 1989, Kohl's handling of the East German issue would become the turning point of his chancellorship. Kohl, like most West Germans, was initially caught unaware when the Socialist Unity Party was toppled in late 1989. Well aware of his constitutional mandate to seek German unity, he immediately moved to make it a reality. Taking advantage of the historic political changes occurring in East Germany, Kohl presented a ten-point plan for "Overcoming of the division of Germany and Europe" without consulting his coalition partner, the FDP, or the Western Allies. In February 1990, he visited the Soviet Union seeking a guarantee from Mikhail Gorbachev that the USSR would allow German reunification to proceed. One month later, the Party of Democratic Socialism — the renamed SED — was roundly defeated by a grand coalition headed by the East German counterpart of Kohl's CDU, which ran on a platform of speedy reunification.

On 18 May 1990, Kohl signed an economic and social union treaty with East Germany. This treaty stipulated that when reunification took place, it would be under the quicker provisions of Article 23 of the Basic Law. That article stated that any new states could adhere to the Basic Law by a simple majority vote. The alternative would have been the more protracted route of drafting a completely new constitution for the newly reunified country, as provided by Article 146 of the Basic Law. An Article 146 reunification would have opened up contentious issues in West Germany, and would have been impractical in any case since by then East Germany was in a state of utter collapse. In contrast, an Article 23 reunification could be completed in as little as six months.

Over the objections of Bundesbank president Karl Otto Pöhl, he allowed a 1:1 exchange rate for wages, interest and rent between the West and East Marks. In the end, this policy would seriously hurt companies in the new federal states. Together with Foreign Minister Hans-Dietrich Genscher, Kohl was able to resolve talks with the former Allies of World War II to allow German reunification. He received assurances from Gorbachev that a reunified Germany would be able to choose which international alliance it wanted to join, although Kohl made no secret that he wanted the reunified Germany to inherit West Germany's seats at NATO and the EC.

A reunification treaty was signed on 31 August 1990, and was overwhelmingly approved by both parliaments on 20 September 1990. On 3 October 1990, East Germany officially ceased to exist, and its territory joined the Federal Republic as the five states of Brandenburg, Mecklenburg-Vorpommern, Saxony, Saxony-Anhalt and Thuringia. These states had been the original five states of East Germany before being abolished in 1952, and had been reconstituted in August. East and West Berlin were reunited as the capital of the enlarged Federal Republic. After the fall of the Berlin Wall, Kohl confirmed that historically German territories east of the Oder-Neisse line were definitively part of Poland, thereby relinquishing any claim Germany had to them. In 1993, Kohl confirmed, via treaty with the Czech Republic, that Germany would no longer bring forward territorial claims as to the pre-1945 ethnic German Sudetenland. This treaty was a disappointment for the German Heimatvertriebene ("displaced persons”).

Thursday, June 15, 2017

Coming: Better Solar Cells

‘Magic’ Alloy Could Spur Next
Generation of Solar Cells

ANN ARBOR—June 15, 2017 -- In what could be a major step forward for a new generation of solar cells called "concentrator photovoltaics," University of Michigan researchers have developed a new semiconductor alloy that can capture the near-infrared light located on the leading edge of the visible light spectrum.

Easier to manufacture and at least 25 percent less costly than previous formulations, it's believed to be the world's most cost-effective material that can capture near-infrared light—and is compatible with the gallium arsenide semiconductors often used in concentrator photovoltaics.

Concentrator photovoltaics gather and focus sunlight onto small, high-efficiency solar cells made of gallium arsenide or germanium semiconductors. They're on track to achieve efficiency rates of over 50 percent, while conventional flat-panel silicon solar cells top out in the mid-20s.

"Flat-panel silicon is basically maxed out in terms of efficiency," said Rachel Goldman, U-M professor of materials science and engineering, and physics, whose lab developed the alloy. "The cost of silicon isn't going down and efficiency isn't going up. Concentrator photovoltaics could power the next generation."

Varieties of concentrator photovoltaics exist today. They are made of three different semiconductor alloys layered together. Sprayed onto a semiconductor wafer in a process called molecular-beam epitaxy—a bit like spray painting with individual elements—each layer is only a few microns thick. The layers capture different parts of the solar spectrum; light that gets through one layer is captured by the next.

But near-infrared light slips through these cells unharnessed. For years, researchers have been working toward an elusive "fourth layer" alloy that could be sandwiched into cells to capture this light. It's a tall order; the alloy must be cost-effective, stable, durable and sensitive to infrared light, with an atomic structure that matches the other three layers in the solar cell.

Getting all those variables right isn't easy, and until now, researchers have been stuck with prohibitively expensive formulas that use five elements or more.

To find a simpler mix, Goldman's team devised a novel approach for keeping tabs on the many variables in the process. They combined on-the-ground measurement methods including X-ray diffraction done at U-M and ion beam analysis done at Los Alamos National Laboratory with custom-built computer modeling.

Using this method, they discovered that a slightly different type of arsenic molecule would pair more effectively with the bismuth. They were able to tweak the amount of nitrogen and bismuth in the mix, enabling them to eliminate an additional manufacturing step that previous formulas required. And they found precisely the right temperature that would enable the elements to mix smoothly and stick to the substrate securely.

"'Magic' is not a word we use often as materials scientists," Goldman said. "But that's what it felt like when we finally got it right."

The advance comes on the heels of another innovation from Goldman's lab that simplifies the "doping" process used to tweak the electrical properties of the chemical layers in gallium arsenide semiconductors. During doping, manufacturers apply a mix of chemicals called "designer impurities" to change how semiconductors conduct electricity and give them positive and negative polarity similar to the electrodes of a battery. The doping agents usually used for gallium arsenide semiconductors are silicon on the negative side and beryllium on the positive side.

The beryllium is a problem—it's toxic and it costs about 10 times more than silicon dopants. Beryllium is also sensitive to heat, which limits flexibility during the manufacturing process. But the U-M team discovered that by reducing the amount of arsenic below levels that were previously considered acceptable, they can "flip" the polarity of silicon dopants, enabling them to use the cheaper, safer element for both the
positive and negative sides.


"Being able to change the polarity of the carrier is kind of like atomic 'ambidexterity,'" said Richard Field, a former U-M doctoral student who worked on the project. "Just like people with naturally born ambidexterity, it's fairly uncommon to find atomic impurities with this ability."

Together, the improved doping process and the new alloy could make the semiconductors used in concentrator photovoltaics as much as 30 percent cheaper to produce, a big step toward making the high-efficiency cells practical for large-scale electricity generation.

"Essentially, this enables us to make these semiconductors with fewer atomic spray cans, and each can is significantly less expensive," Goldman said. "In the manufacturing world, that kind of simplification is very significant. These new alloys and dopants are also more stable, which gives makers more flexibility as the semiconductors move through the manufacturing process."

The new alloy is detailed in a paper titled "Bi-enhanced N incorporation in GaAsNBi alloys," published June 15 in Applied Physics Letters. The research is supported by the National Science Foundation and the U.S. Department of Energy Office of Science Graduate Student Research.

The doping advances are detailed in a paper titled "Influence of surface reconstruction on dopant incorporation and transport properties of GaAs(Bi) alloys." It was published in the Dec. 26, 2016, issue of Applied Physics Letters. The research was supported by the National Science Foundation.