The Great London [Search results for color] 

Biological anthropologist Sharon DeWitte studies ancient skeletons that can open a window onto the human history she hopes to illuminate. But as she and graduate student Samantha Yaussy show in a recently published study, some of the markers on the skeletons that scientists use to decipher the past might need to be looked at in a new light.

DeWitte, one of the world's foremost experts on the Black Death, which killed one-third to one-half of Europe's inhabitants over just seven years in a mid-1300s pandemic, is also interested in the periods before and after the Black Death, both in times of famine and, for the medieval era, relative plenty.

"This was a time when you had all of these other stressors existing, like multiple infectious diseases, people living in really crowded conditions, lack of hygiene," DeWitte says. "I'm interested in looking at how famine might have affected subsequent patterns of health and risks of mortality."

In research recently published in the >American Journal of Physical Anthropology, Yaussy and DeWitte worked with skeletal remains excavated from London's St. Mary Spital cemetery, which was in use from about 1120 to 1540 A.D. The cemetery was organized well enough over those years that modern-day researchers can assign burial groupings according to location to a number of shorter time periods within that larger 420-year time frame. Because they were focused on the effects of famine, the scientists specifically excluded burials from the Black Death era in the study.

The way that people were buried in plots also provided important data. Large group burials within a single grave were taken to be the result of catastrophic famine losses over short periods of time, whereas single interments were categorized as "attritional" deaths, that is, deaths in "normal" times.

Using a total of more than 1,500 individual adult remains that were almost evenly divided between famine deaths and normal deaths, DeWitte and Yaussy carefully examined the skeletons for markers that are indicative of stress during the individual's lifetime.

One stress marker they looked for is called "linear enamel hypoplasia" (LEH), which is a horizontal groove on a tooth that results from childhood physiological stress or trauma sometime between 6 months and 6 years of age, when the tooth is forming in the jaw.

"It could be the result of an infection, lack of nutrition, or even breaking a leg," says Yaussy. "Your enamel just stops creating itself for a day or a little longer. It starts back up again, but during that time when it was shut off, there's no enamel on that portion of the teeth, and it leaves a groove."

They found that that stress marker, LEH, was significantly correlated with famine. "It was a pretty sensitive indicator of famine burials," Yaussy says. "Having that early life insult seems to instigate this pattern of lifelong frailty, so when a famine event occurs, it causes mortality in those individuals."

Another indicator of life stress, though, turned out to be a horse of a different color. Using shin bones (tibia), the researchers looked for what's called periosteal lesions. It's a place on the bone where new growth on the surface has occurred in response to physical or physiological stress.

"When it's put under stress, and it can be from something like an infection, or a break, or even just stress from carrying heavy buckets all day, bone can grow onto itself and strengthen itself," Yaussy says. "These are nonspecific -- we're not necessarily saying that it was an infection that caused it, or that it was from someone hitting their shin repeatedly. I just see that there was bone growth there, so there's some stressor that's causing the bone to generate more bone."

In contrast to people with the LEH indicator, individuals with areas of bone regrowth were correlated with periods of normal, or attritional, death. That result came as a something of a surprise to colleagues in the field.

"This project was a bit of a shock to some of the people at the paleopathology meetings where we presented it," Yaussy says. "A lot of people have been thinking that things like periosteal lesions are bad, that people who had them weren't especially healthy. But this study in part might be saying that those people were actually pretty healthy. It takes time, a couple of weeks, to build up this bone, so it could be that if there was some stress event that was substantial enough to kill a person before they could even register a response, we wouldn't be seeing it on the bone now."

The unexpected result helps inform DeWitte in the larger goal of looking at what happens to populations after crises, such as the Black Death or famines, pass, and particularly how cultural norms might influence the outcomes.

"What I'm interested in going forward is looking at access to resources before the Black Death, during normal conditions during famine conditions, and then after the Black Death, again during normal and famine conditions," Dewitte says. "Seeing if there were social factors that affected people's access to resources when there was little available and then when they became abundant again."

"I think this might have implications for living populations, understanding how social, economic and political factors affect access to resources beyond the actual amount of resources that are available."

Author: Steven Powell | Source: University of South Carolina [May 02, 2016]

Scientists at UCL have observed how a widespread polar wind is driving gas from the atmosphere of Saturn's moon Titan. The team analysed data gathered over seven years by the international Cassini probe, and found that the interactions between Titan's atmosphere, and the solar magnetic field and radiation, create a wind of hydrocarbons and nitriles being blown away from its polar regions into space. This is very similar to the wind observed coming from Earth's polar regions.

Titan is a remarkable object in the Solar System. Like Earth and Venus, and unlike any other moon, it has a rocky surface and a thick atmosphere. It is the only object in the Solar System aside from Earth to have rivers, rainfall and seas. It is bigger than the planet Mercury.

Thanks to these unique features, Titan has been studied more than any moon other than Earth's, including numerous fly-bys by the Cassini probe, as well as the Huygens lander which touched down in 2004. On board Cassini is an instrument partly designed at UCL, the Cassini Plasma Spectrometer (CAPS), which was used in this study.

"Titan's atmosphere is made up mainly of nitrogen and methane, with 50% higher pressure at its surface than on Earth," said Andrew Coates (UCL Mullard Space Science Laboratory), who led the study. "Data from CAPS proved a few years ago that the top of Titan's atmosphere is losing about seven tonnes of hydrocarbons and nitriles every day, but didn't explain why this was happening. Our new study provides evidence for why this is happening."

Hydrocarbons are a category of molecules that includes methane, as well as other familiar substances including petrol, natural gas and bitumen. Nitriles are molecules with nitrogen and carbon tightly bound together.

The new research, published today in the journal Geophysical Research Letters, explains that this atmospheric loss is driven by a polar wind powered by an interaction between sunlight, the solar magnetic field and the molecules present in the upper atmosphere.

"Although Titan is ten times further from the Sun than Earth is, its upper atmosphere is still bathed in light," says Coates. "When the light hits molecules in Titan's ionosphere, it ejects negatively charged electrons out of the hydrocarbon and nitrile molecules, leaving a positively charged particle behind. These electrons, known as photoelectrons, have a very specific energy of 24.1 electronvolts, which means they can be traced by the CAPS instrument, and easily distinguished from other electrons, as they propagate through the surrounding magnetic field."

Unike Earth, Titan has no magnetic field of its own, but is surrounded by Saturn's rapidly rotating magnetic field, which drapes forming a comet-like tail around the moon. In 23 fly-bys which passed through Titan's ionosphere or its magnetic tail, CAPS detected measurable quantities of these photoelectrons up to 6.8 Titan radii away from the moon, because they can easily travel along the magnetic field lines.

The team found that these negatively-charged photoelectrons, spread throughout Titan's ionosphere and the tail, set up an electrical field. The electrical field, in turn, is strong enough to pull the positively charged hydrocarbon and nitrile particles from the atmosphere throughout the sunlit portion of the atmosphere, setting up the widespread 'polar wind' that scientists have observed there.

This phenomenon has only been observed on Earth before, in the polar regions where Earth's magnetic field is open. As Titan lacks its own magnetic field the same thing can occur over wider regions, not just near the poles. A similarly widespread 'polar wind' is strongly suspected to exist both on Mars and Venus -- the two planets in the Solar System which are most Earth-like. It gives further evidence of how Titan, despite its location in orbit around a gas giant in the outer Solar System, is one of the most Earth-like objects ever studied.

Source: University College London [June 18, 2015]

An extraordinary archaeological discovery was revealed in an excavation of the Israel Antiquities Authority prior to the construction of a road being built at the initiative of the Netivei Israel Company. During the excavation, carried out as part of the Jezreel Valley Railway Project between Ha-‘Emekim Junction and Yagur Junction, remains of the oldest kilns in Israel were discovered where commercial quantities of raw glass were produced. These kilns, c. 1,600 years old (dating to the Late Roman period), indicate that the Land of Israel was one of the foremost centers for glass production in the ancient world.

According to Yael Gorin-Rosen, head curator of the Israel Antiquities Authority Glass Department, “This is a very important discovery with implications regarding the history of the glass industry both in Israel and in the entire ancient world. We know from historical sources dating to the Roman period that the Valley of ‘Akko was renowned for the excellent quality sand located there, which was highly suitable for the manufacture of glass. Chemical analyses conducted on glass vessels from this period which were discovered until now at sites in Europe and in shipwrecks in the Mediterranean basin have shown that the source of the glass is from our region. Now, for the first time, the kilns have been found where the raw material was manufactured that was used to produce this glassware”.

The excavation of the kilns has caused great excitement in recent weeks among glass researchers throughout the world, some of whom have come especially to Israel in order to see this discovery first hand. According to Professor Ian Freestone of the University College London, who specializes in identifying the chemical composition of glass, "This is a sensational discovery and it is of great significance for understanding the entire system of the glass trade in antiquity. This is evidence that Israel constituted a production center on an international scale; hence its glassware was widely distributed throughout the Mediterranean and Europe”.

This enormously important site was discovered by chance last summer by archaeologist Abdel Al-Salam Sa‘id, an inspector with the Israel Antiquities Authority. While overseeing infrastructure work being conducted on the new railway line from Haifa to the east, he suddenly observed chunks of glass, a floor and an ash layer inside a trench. He halted construction work at the site and began preparations for an archaeological excavation, the important results of which are now evident.

According to Abdel Al-Salam Sa‘id, the excavation direction, “We exposed fragments of floors, pieces of vitrified bricks from the walls and ceiling of the kilns, and clean raw glass chips. We were absolutely overwhelmed with excitement when we understood the great significance of the finds”.

The kilns that were revealed consisted of two built compartments: a firebox where kindling was burnt to create a very high temperature, and a melting chamber – in which the raw materials for the glass (clean beach sand and salt) were inserted and melted together at a temperature of c. 1,200 C degrees. The glass was thus heated for a week or two until enormous chunks of raw glass were produced, some of which weighed in excess of ten tons. At the end of the manufacturing process the kilns were cooled; the large glass chunks that were manufactured were broken into smaller pieces and were sold to workshops where they were melted again in order to produce glassware.

During the Early Roman period the use of glass greatly expanded due to its characteristics: its transparency, beauty, the delicacy of the vessels and the speed with which they could be produced by blowing – an inexpensive technique adopted at the time that lowered production costs. Glass was used in almost every household from the Roman period onward, and it was also utilized in the construction of public buildings in the form of windows, mosaics and lighting fixtures. Consequently, large quantities of raw glass were required which were prepared on an industrial scale in specialized centers. The installation that was discovered in the excavation is an example of one of these ancient production facilities.

According to a price edict circulated by the Roman emperor Diocletian in the early fourth century CE, there were two kinds of glass: the first was known as Judean glass (from the Land of Israel) and the second – Alexandrian glass (from Alexandria, Egypt). Judean glass was a light green color and less expensive than Egyptian glass. The question was: Where were the centers that manufactured this Judean glass that was a branded product known throughout the Roman Empire and whose price was engraved on stone tablets so as to ensure fair trade. The current discovery completes the missing link in the research and indicates the location where the famous Judean glass was produced.

In a few months time the public will be able to see this discovery first-hand when it will be exhibited at the "Carmel Zvulun" Regional High school, in the Zevulun Regional Council.

Additional Background Information

Glass production kilns that date to the sixth or early seventh century CE were previously found at Apollonia in Herzliya and are c. 200 years later than the current discovery. The largest glass production facility from antiquity that has been found so far was exposed in the Bet Eliezer neighborhood in Hadera where it was dated to the seventh–eighth centuries CE, and the latest evidence we have of glass production in the country was revealed at Bet She‘arim (next to Khirbat ‘Asafna), dated to the late eighth and early ninth centuries CE.

The kilns that were just recently found are the earliest ones to be discovered so far in Israel. Their relatively good state of preservation will make it possible to better understand the production process. Researchers now hope that by means of its chemical composition they will be able to trace the export of the glass throughout the Roman Empire.

The raw glass industry at Khirbat ‘Asafna was part of an extensive industrial zone where there were oil presses, wine presses and a glassware workshop which was excavated in the 1960’s by an American archaeological expedition

Source: Israel Antiquities Authority [April 11, 2016]

A team of Caltech researchers that has spent years searching for the earliest objects in the universe now reports the detection of what may be the most distant galaxy ever found. In an article published August 28, 2015 in Astrophysical Journal Letters, Adi Zitrin, a NASA Hubble Postdoctoral Scholar in Astronomy, and Richard Ellis -- who recently retired after 15 years on the Caltech faculty and is now a professor of astrophysics at University College, London -- describe evidence for a galaxy called EGS8p7 that is more than 13.2 billion years old. The universe itself is about 13.8 billion years old.

Earlier this year, EGS8p7 had been identified as a candidate for further investigation based on data gathered by NASA's Hubble Space Telescope and the Spitzer Space Telescope. Using the multi-object spectrometer for infrared exploration (MOSFIRE) at the W.M. Keck Observatory in Hawaii, the researchers performed a spectrographic analysis of the galaxy to determine its redshift. Redshift results from the Doppler effect, the same phenomenon that causes the siren on a fire truck to drop in pitch as the truck passes. With celestial objects, however, it is light that is being "stretched" rather than sound; instead of an audible drop in tone, there is a shift from the actual color to redder wavelengths.

Redshift is traditionally used to measure distance to galaxies, but is difficult to determine when looking at the universe's most distant -- and thus earliest -- objects. Immediately after the Big Bang, the universe was a soup of charged particles -- electrons and protons -- and light (photons). Because these photons were scattered by free electrons, the early universe could not transmit light. By 380,000 years after the Big Bang, the universe had cooled enough for free electrons and protons to combine into neutral hydrogen atoms that filled the universe, allowing light to travel through the cosmos. Then, when the universe was just a half-billion to a billion years old, the first galaxies turned on and reionized the neutral gas. The universe remains ionized today.

Prior to reionization, however, clouds of neutral hydrogen atoms would have absorbed certain radiation emitted by young, newly forming galaxies -- including the so-called Lyman-alpha line, the spectral signature of hot hydrogen gas that has been heated by ultraviolet emission from new stars, and a commonly used indicator of star formation.

Because of this absorption, it should not, in theory, have been possible to observe a Lyman-alpha line from EGS8p7.

"If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission," says Zitrin. "We expect that most of the radiation from this galaxy would be absorbed by the hydrogen in the intervening space. Yet still we see Lyman-alpha from this galaxy."

They detected it using the MOSFIRE spectrometer, which captures the chemical signatures of everything from stars to the distant galaxies at near-infrared wavelengths (0.97-2.45 microns, or millionths of a meter).

"The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the universe should be full of absorbing hydrogen clouds," Ellis says. Prior to their discovery, the farthest detected galaxy had a redshift of 7.73.

One possible reason the object may be visible despite the hydrogen-absorbing clouds, the researchers say, is that hydrogen reionization did not occur in a uniform manner. "Evidence from several observations indicate that the reionization process probably is patchy," Zitrin says. "Some objects are so bright that they form a bubble of ionized hydrogen. But the process is not coherent in all directions."

"The galaxy we have observed, EGS8p7, which is unusually luminous, may be powered by a population of unusually hot stars, and it may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times," says Sirio Belli, a Caltech graduate student who worked on the project.

"We are currently calculating more thoroughly the exact chances of finding this galaxy and seeing this emission from it, and to understand whether we need to revise the timeline of the reionization, which is one of the major key questions to answer in our understanding of the evolution of the universe," Zitrin says.

Author: Rod Pyle | Source: California Institute of Technology [September 04, 2015]