Amazing Science

The technique used by Brand to create these pieces is not one of conventional holography. He meticulously controls the unique shape of thousands of tiny optical pieces placed on a surface creating a 3D effect when the light source or viewer moves. This is essentially a mathematical problem in differential geometry and combinatorial optimization. Brand was the first person to correctly describe this technique in 2008 even though it dates back as early as the 1930s (check out his paper for details).

Specular holograms by Matthew Brand currently on display at the new Museum of Mathematics in New York.

Male cuttlefish compete for females with a repertoire of visually dramatic behaviors. Laboratory experiments have explored this system in Sepia officinalis but corroborative field data have eluded collection attempts by many researchers. While SCUBA diving in Turkey, a group of biologists fortuitously filmed an intense sequence of consort/intruder behaviors in which the consort lost then regained his female mate from the intruder. These agonistic bouts escalated in stages, leading to fast dramatic expression of the elaborate Intense Zebra Display and culminating in biting and inking as the intruder male attempted a forced copulation of the female. When analyzed in the context of game theory, the patterns of fighting behavior were more consistent with mutual assessment than self assessment of fighting ability. Additional observations of these behaviors in nature are needed to conclusively determine which models best represent conflict resolution, but these field observations agree with laboratory findings and provide a valuable perspective.

CRISPR-associated protein 9 (Cas9)-mediated genome editing provides a promising cure for HIV-1/AIDS; however, gene delivery efficiency in vivo remains an obstacle to overcome.

A group of scientists now demonstrate the feasibility and efficiency of excising the HIV-1 provirus in three different animal models using an all-in-one adeno-associated virus (AAV) vector to deliver multiplex single-guide RNAs (sgRNAs) plus Staphylococcus aureus Cas9 (saCas9). The quadruplex sgRNAs/saCas9 vector outperformed the duplex vector in excising the integrated HIV-1 genome in cultured neural stem/progenitor cells from HIV-1 Tg26 transgenic mice.

Intravenously injected quadruplex sgRNAs/saCas9 AAV-DJ/8 excised HIV-1 proviral DNA and significantly reduced viral RNA expression in several organs/tissues of Tg26 mice. In EcoHIV acutely infected mice, intravenously injected quadruplex sgRNAs/saCas9 AAV-DJ/8 reduced systemic EcoHIV infection, as determined by live bioluminescence imaging. Additionally, this quadruplex vector induced efficient proviral excision, as determined by PCR genotyping in the liver, lungs, brain, and spleen. Finally, in humanized bone marrow/liver/thymus (BLT) mice with chronic HIV-1 infection, successful proviral excision was detected by PCR genotyping in the spleen, lungs, heart, colon, and brain after a single intravenous injection of quadruplex sgRNAs/saCas9 AAV-DJ/8. In conclusion, in vivo excision of HIV-1 proviral DNA by sgRNAs/saCas9 in solid tissues/organs can be achieved via AAV delivery, a significant step toward human clinical trials.

Genetic map showing how dog breeds are related provides a wealth of information about their origins.

What a tangled web humans have weaved for domestic dog breeds. A new family tree of dogs containing more than 160 breeds reveals the hidden history of man’s best friend, and even hints how studying canine genomes might help with research into human disease.

In a study published on 25 April 2017 in Cell Reports, scientists examined the genomes of 1,346 dogs to create one of the most diverse maps produced so far tracing the relationship between breeds1. The map shows the types of dog that people crossed to create modern breeds and reveals that canines bred to perform similar functions, such as working and herding dogs, don't necessarily share the same origins. The analysis even hints at an ancient type of dog that could have come over to the Americas with people thousands of years before Christopher Columbus arrived in the New World.

The new work could come as a surprise to owners and breeders who are familiar with how dogs are grouped into categories. “You would think that all working dogs or all herding dogs are related, but that isn’t the case,” says Heidi Parker, a biologist at the US National Institutes of Health (NIH) in Bethesda, Maryland, and a study author.

When geneticists tried to map out herding-dog lineages in the past, they couldn’t do so accurately. Parker and Elaine Ostrander, also a biologist at the NIH and a study author, say that this was because herding dogs emerged through selective breeding at multiple times and in many different places. “In retrospect, that makes sense,” says Ostrander. “What qualities you’d want in a dog that herds bison are different from mountain goats, which are different from sheep, and so on.”

Most of the breeds in the study arose from dog groups that originated in Europe and Asia. But domestic dogs came to the Americas thousands of years ago, when people crossed the Bering land bridge linking Alaska and Siberia. These New World dogs later disappeared when European and Asian dogs arrived in the Americas. Researchers have looked for the genetic legacy of these ancient canines in the DNA of modern American breeds, but have found little evidence until now.

The way that two South American breeds, the Peruvian hairless dog and the Xoloitzcuintli, clustered together on the family tree suggested to Ostrander and Parker that those animals could share genes not found in any of the other breeds in their analysis. Parker thinks that those genes could have come from dogs that were present in the Americas before Columbus’s arrival. “I think our view of the formation of modern dog breeds has historically been one-dimensional,” says Bob Wayne, an evolutionary biologist at the University of California, Los Angeles. “We didn’t consider that the process has a deep historical legacy.”

That extends to what was probably the first period of domestication for canines in hunter-gatherer times. Ostrander and Parker think that dog breeds underwent two major periods of diversification. Thousands of years ago, dogs were selected for their skills, whereas a few hundred years ago, the animals were bred for physical traits. “You would never be able to find something like this with cows or cats,” says Wayne, “We haven’t done this kind of intense deliberate breeding with anything but dogs.”

What's happening behind those houses? Pictured here are not auroras but nearby light pillars, a nearby phenomenon that can appear as a distant one. In most places on Earth, a lucky viewer can see a Sun-pillar, a column of light appearing to extend up from the Sun caused by flat fluttering ice-crystals reflecting sunlight from the upper atmosphere. Usually these ice crystals evaporate before reaching the ground. During freezing temperatures, however, flat fluttering ice crystals may form near the ground in a form of light snow, sometimes known as a crystal fog. These ice crystals may then reflect ground lights in columns not unlike a Sun-pillar. The featured image was taken in FortWainwright near Fairbanks in central Alaska.

Using a specialized electron microscope outfitted with a pattern generator, scientists turned an imaging instrument into a lithography tool that could be used to create and study materials with new properties.

The ability to pattern materials at ever-smaller sizes—using electron-beam lithography (EBL), in which an electron-sensitive material is exposed to a focused beam of electrons, as a primary method—is driving advances in nanotechnology. When the feature size of materials is reduced from the macroscale to the nanoscale, individual atoms and molecules can be manipulated to dramatically alter material properties, such as color, chemical reactivity, electrical conductivity, and light interactions.

In the ongoing quest to pattern materials with ever-smaller feature sizes, scientists at the Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory—have recently set a new record. Performing EBL with a scanning transmission electron microscope (STEM), they have patterned thin films of the polymer poly(methyl methacrylate), or PMMA, with individual features as small as one nanometer (nm), and with a spacing between features of 11 nm, yielding an areal density of nearly one trillion features per square centimeter. These record achievements are published in the April 18 online edition of Nano Letters.

“Our goal at CFN is to study how the optical, electrical, thermal, and other properties of materials change as their feature sizes get smaller,” said lead author Vitor Manfrinato, a research associate in CFN’s electron microscopy group who began the project as a CFN user while completing his doctoral work at MIT. “Until now, patterning materials at a single nanometer has not been possible in a controllable and efficient way.”

Commercial EBL instruments typically pattern materials at sizes between 10 and 20 nanometers. Techniques that can produce higher-resolution patterns require special conditions that either limit their practical utility or dramatically slow down the patterning process. Here, the scientists pushed the resolution limits of EBL by installing a pattern generator—an electronic system that precisely moves the electron beam over a sample to draw patterns designed with computer software—in one of CFN’s aberration-corrected STEMs, a specialized microscope that provides a focused electron beam at the atomic scale.

“We converted an imaging tool into a drawing tool that is capable of not only taking atomic-resolution images but also making atomic-resolution structures,” said coauthor Aaron Stein, a senior scientist in the electronic nanomaterials group at CFN.

Forget high-speed cameras capturing 100 000 images per second. A research group at Lund University in Sweden has developed a camera that can film at a rate equivalent to five trillion images per second, or events as short as 0.2 trillionths of a second. This is faster than has previously been possible.

Scientists have created an "artificial womb" in the hopes of someday using the device to save babies born extremely prematurely. So far the device has only been tested on fetal lambs. A study published Tuesday involving eight animals found the device appears effective at enabling very premature fetuses to develop normally for about a month.

"We've been extremely successful in replacing the conditions in the womb in our lamb model," says Alan Flake, a fetal surgeon at Children's Hospital of Philadelphia who led the study published in the journal Nature Communications.

"They've had normal growth. They've had normal lung maturation. They've had normal brain maturation. They've had normal development in every way that we can measure it," Flake says. Flake says the group hopes to test the device on very premature human babies within three to five years. "What we tried to do is develop a system that mimics the environment of the womb as closely as possible," Flake says. "It's basically an artificial womb."

Troodontids were theropod dinosaurs closely related to birds. Here, Xu and colleagues describe a new, feathered troodontid species,Jianianhualong tengi, dating from the Lower Cretaceous period in China that provides insight into troodontid mosaic evolution and paravian feathering.

Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Paleontologists now report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical features that are transitional between long-armed basal troodontids and derived short-armed ones, shedding new light on troodontid character evolution. The finding indicates that troodontid feathering is similar to Archaeopteryx in having large arm and leg feathers as well as frond-like tail feathering, confirming that these feathering characteristics were widely present among basal paravians. Most significantly, the taxon has the earliest known asymmetrical troodontid feathers, suggesting that feather asymmetry was ancestral to Paraves. This taxon also displays a mosaic distribution of characters like Sinusonasus, another troodontid with transitional anatomical features.

These images from the Radar instrument aboard NASA's Cassini spacecraft show the evolution of a transient feature in the large hydrocarbon sea named Ligeia Mare on Saturn's moon Titan.

Analysis by Cassini scientists indicates that the bright features, informally known as the "magic island," are a phenomenon that changes over time. They conclude that the brightening is due to either waves, solids at or beneath the surface or bubbles, with waves thought to be the most likely explanation. They think tides, sea level and seafloor changes are unlikely to be responsible for the brightening.

The images in the column at left show the same region of Ligeia Mare as seen by Cassini's radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015.

The bottom image was acquired by Cassini on Jan. 11, 2015, and adds another snapshot in time as Cassini continues to monitor the ephemeral feature (previously highlighted in PIA18430). The feature is apparent in the images from 2013 and 2014, but it is not present in other images of the region.

Cassini has observed similar transient features elsewhere in Ligeia Mare, and also in Kraken Mare (see PIA19047). These features are the first instances of active processes in Titan's lakes and seas to be confirmed by multiple detections. Their changing nature demonstrates that Titan's seas are not stagnant, but rather, dynamic environments.

The Cassini radar team plans to re-observe this particular region of Ligeia Mare one more time during Cassini's final close flyby of Titan in April 2017. The results may further illuminate the phenomenon responsible for the appearance of the transient features.

The large image panel shows Ligeia Mare in its entirety. Ligeia is Titan's second-largest liquid hydrocarbon sea, and has a total area of about 50,000 square miles (130,000 square kilometers), making it 50 percent larger than Lake Superior on Earth. This panel is a mosaic of five synthetic aperture radar images acquired by Cassini between 2007 and 2014. It shows a region approximately 330 by 305 miles (530 by 490 kilometers) in area.

An earlier version of the mosaic was released as PIA17031; the new version includes new data to fill in some gaps in coverage and to improve the quality of coverage in some of the previously imaged areas.

The formation of a human embryo starts with the fertilization of the oocyte by the sperm cell. This yields the zygote, the primordial cell that carries one copy each of the maternal and paternal genomes. However, this genetic information starts being expressed only after the zygote divides a couple of times. But what triggers this process, called “zygotic genome activation”, was unknown until now. EPFL scientists have just found that members of the DUX family of proteins are responsible for igniting the gene expression program of the nascent embryo. Published in Nature Genetics, this discovery is a milestone for developmental biology.

Alberto de Iaco, a postdoc in the lab of Didier Trono at EPFL, drew upon a seemingly irrelevant study of patients suffering from a form of muscular dystrophy where mutations lead to the production in muscle cells of a protein called DUX4, which is normally detected only at the earliest stage of human embryonic development.  De Iaco also found that when DUX4 is forcibly produced in muscle cells, it turns on a whole set of genes that are expressed during zygotic genome activation. This was what first suggested that DUX4 could be the key regulator of this seminal event. 

To confirm this, the researchers analyzed publicly available data to determine what components of the human genome are expressed during the first few days of embryonic development. They found that DUX4 is one of the very first genes expressed at this stage, releasing a high concentration of its protein product just before zygotic genome activation.  In line with this lead, the scientists could show that the DUX4 protein binds to the regulatory region of genes that are induced during zygotic genome activation, stimulating their expression. 

Next, they looked at mouse embryonic stem cells, which contain the mouse version of the DUX4 gene (called simply DUX). When in culture, a small fraction of these cells exhibit a any given time the gene expression pattern of 2-cell stage embryos, before cycling back to the features of more advanced embryonic cells. But when the EPFL researchers deleted the DUX gene, this process stopped, the appearance of the 2-cell stage-like subpopulation was suppressed. 

The final piece of evidence came when the EPFL scientists removed the DUX gene from fertilized mouse oocytes using CRISPR/Cas9 genome editing. This prevented zygotic genome activation altogether, and precluded the growth of embryos beyond the first couple of cell divisions.

The study points to DUX4, and by extension the DUX family of proteins, as the master regulator responsible for kick-starting genome expression at the earliest stage of embryonic life in humans, mouse and probably all placental mammals.

In a paper published today in Nature Physics(link is external), the ALICE collaboration reports that proton collisions sometimes present similar patterns to those observed in the collisions of heavy nuclei. This behavior was spotted through observation of so-called strange hadrons in certain proton collisions in which a large number of particles are created. Strange hadrons are well-known particles with names such as Kaon, Lambda, Xi and Omega, all containing at least one so-called strange quark. The observed ‘enhanced production of strange particles’ is a familiar feature of quark-gluon plasma, a very hot and dense state of matter that existed just a few millionths of a second after the Big Bang, and is commonly created in collisions of heavy nuclei. But it is the first time ever that such a phenomenon is unambiguously observed in the rare proton collisions in which many particles are created. This result is likely to challenge existing theoretical models that do not predict an increase of strange particles in these events.

"We are very excited about this discovery,” said Federico Antinori, Spokesperson of the ALICE collaboration. “We are again learning a lot about this primordial state of matter. Being able to isolate the quark-gluon-plasma-like phenomena in a smaller and simpler system, such as the collision between two protons, opens up an entirely new dimension for the study of the properties of the fundamental state that our universe emerged from.”

The study of the quark-gluon plasma provides a way to investigate the properties of strong interaction, one of the four known fundamental forces, while enhanced strangeness production is a manifestation of this state of matter. The quark-gluon plasma is produced at sufficiently high temperature and energy density, when ordinary matter undergoes a transition to a phase in which quarks and gluons become ‘free’ and are thus no longer confined within hadrons. These conditions can be obtained at the Large Hadron Collider by colliding heavy nuclei at high energy. Strange quarks are heavier than the quarks composing normal matter, and typically harder to produce. But this changes in presence of the high energy density of the quark-gluon plasma, which rebalances the creation of strange quarks relative to non-strange ones. This phenomenon may now have been observed within proton collisions as well.

In particular, the new results show that the production rate of these strange hadrons increases with the ‘multiplicity’ – the number of particles produced in a given collision – faster than that of other particles generated in the same collision. While the structure of the proton does not include strange quarks, data also show that the higher the number of strange quarks contained in the induced hadron, the stronger is the increase of its production rate. No dependence on the collision energy or the mass of the generated particles is observed, demonstrating that the observed phenomenon is related to the strange quark content of the particles produced. Strangeness production is in practice determined by counting the number of strange particles produced in a given collision, and calculating the ratio of strange to non-strange particles.

Enhanced strangeness production had been suggested as a possible consequence of quark-gluon plasma formation since the early eighties, and discovered in collisions of nuclei in the nineties by experiments at CERN[1]’s Super Proton Synchrotron. Another possible consequence of the quark gluon plasma formation is a spatial correlation of the final state particles, causing a distinct preferential alignment with the shape of a ridge. Following its detection in heavy-nuclei collisions, the ridge has also been seen in high-multiplicity proton collisions at the Large Hadron Collider, giving the first indication that proton collisions could present heavy-nuclei-like properties. Studying these processes more precisely will be key to better understand the microscopic mechanisms of the quark-gluon plasma and the collective behaviour of particles in small systems.

The ALICE experiment has been designed to study collisions of heavy nuclei. It also studies proton-proton collisions, which primarily provide reference data for the heavy-nuclei collisions. The reported measurements have been performed with 7 TeV proton collision data from LHC run 1.

Female dragonflies use an extreme tactic to get rid of unwanted suitors: they drop out the sky and then pretend to be dead.

Rassim Khelifa from the University of Zurich, Switzerland, witnessed the behavior for the first time in the moorland hawker dragonfly (Aeshna juncea).

While collecting their larvae in the Swiss Alps, he watched a female crash-dive to the ground while being pursued by a male. The female then lay motionless on her back. Her suitor soon flew away, and the female took off once the coast was clear.

“I was surprised,” says Khelifa, who had never previously seen this in 10 years of studying dragonflies.

You heard right. The Postal Service will debut a new thermochromic ink Forever stamp in June ahead of a rare solar eclipse set for Aug. 21, 2017.

The new issue will transform from an image of a total solar eclipse into an image of the moon when you press it with your finger. The back will feature a U.S. map tracking when the eclipse will appear across the country.

It's the first time a stamp will make use of thermochromic ink, which is sensitive to body heat (and changing temperatures -- which means stamps should be kept away from direct sunlight).

The stamp's photo of the eclipse was taken in Libya by an Arizona-based astrophysicist in 2006.

For rusty space enthusiasts: A total solar eclipse occurs when the moon completely covers the sun, casting a shadow on the Earth, according to NASA. The shadow path of the eclipse, which is 70 miles wide, will move diagonally across the country from west to east, traversing Oregon, Idaho, Montana, Wyoming, Nebraska, Kansas, Iowa, Missouri, Illinois, Kentucky, Tennessee, North Carolina, Georgia and South Carolina. A partial view of the phenomenon will be visible across North America.

"Tens of millions of people in the United States hope to view this rare event, which has not been seen on the U.S. mainland since 1979," the Postal Service said in a statement.