Hearing Loss Found Every sound we hear is the result of sound…

Hearing Loss Found

Every sound we hear is the result of sound waves in the air wobbling tiny hairs found on specialised cells inside the ear. There are two layers of hair cells – inner (stained green) and outer (red) – which turn that physical information into electrical impulses that go to the brain where they are interpreted as sounds. Unfortunately, these delicate hair cells can become damaged over time, leading to age-related hearing loss – a condition that is expected to affect more than 900 million people worldwide by 2050. By focusing on the complex biological processes that control the development and maturation of hair cells, researchers have discovered that a molecule called helios is responsible for converting immature outer hair cells into functional, grown-up ones. Understanding these pathways and learning how to manipulate them could lead to new ways to regenerate hair cells in the ear, potentially providing a way to reverse age-related hearing loss.

Written by Kat Arney

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Colliding Exoplanets

The figure shows one frame from the middle of a hydrodynamical simulation of a high-speed head-on collision between two 10 Earth-mass planets. The temperature range of the material is represented by four colors grey, orange, yellow and red, where grey is the coolest and red is the hottest. Such collisions eject a large amount of the silicate mantle material leaving a high-iron content, high-density remnant planet similar to the observed characteristics of Kepler-107c. Credit: Zoe Leinhardt and Thomas Denman, University of Bristol. High Resolution (jpg) Low Resolution (jpg)

The video shows a hydrodynamical simulation of a high-speed head-on collision between two 10 Earth-mass planets. The temperature range of the material is represented by four colors grey, orange, yellow and red, where grey is the coolest and red is the hottest. Such collisions eject a large amount of the silicate mantle material leaving a high-iron content, high-density remnant planet similar to the observed characteristics of Kepler-107c.  Credit: Zoe Leinhardt and Thomas Denman, University of Bristol. Watch Video

Cambridge, MA — There are currently about 2000 confirmed exoplanets with radii less than about three Earth-radii, and measurements of their densities reveal an astonishing diversity. Some have densities lower than Neptune which is made mostly of volatiles (materials less dense than metal and rock, but Neptune has almost four times the Earth’s radius), while others appear to have rock-like densities, as high as the Earth’s or higher. Such a wide range of compositions may be the product of the different initial conditions in the planet-formation process, or it could be because something dramatic happens to the planet to alter its initial properties as it evolves.

In a new paper in Nature Astronomy, Istituto Nazionale Di Astrofisica (INAF) astronomers Aldo S. Bonomo and Mario Damasso and Center for Astrophysics | Harvard & Smithsonian (CfA) astrophysicist Li Zeng, along with a large team of colleagues, report that a giant collision must have occurred in the exoplanetary system Kepler-107. While there is some observational evidence for the collisional process in our own solar system, so far there has been no unambiguous finding in support of the impact scenario among exoplanets.
Astronomers used to think that low-density planets, like the giants Jupiter, Saturn, Uranus and Neptune, form from cold ices and gas in the outer regions of a young star’s protoplanetary disk; the inner zone builds planets from rocky elements like silicates and iron whose particulates can survive in the hotter environment. Today the picture has become more complicated with hundreds of low-density giant exoplanets discovered orbiting close to their stars. In the case of evolutionary effects, two processes are thought most likely to affect a planet’s density: mass loss from the planet’s atmosphere and/or surface due to evaporation by the host star’s radiation, or a giant collision between planets.
Of the four known planets in Kepler-107, the two innermost ones have nearly identical radii of 1.536 and 1.597 Earth-radii, respectively, (the uncertainty of each is only about 0.2%). Their periods are also similar at 3.18 and 4.90 days, meaning that they orbit relatively nearby each other. Using the HARPS-N spectrograph at the Telescopio Nazionale Galileo in La Palma, the team determined the planet masses, and hence their densities. The observations are surprising — their densities are very different: 5.3 and 12.65 grams per cubic centimeter, respectively. For comparison, water’s density is 1 grams per cubic centimeter and the Earth’s is 5.5 grams per cubic centimeter. The fact that one of the planets has a density more than twice the other cannot be easily explained by stellar radiation effects which should have affected them both in the same way. Moreover, it is the outer one that is denser than the inner one. The astronomers argue instead that a giant impact on one planet, Kepler-107c (the denser planet), stripped off part of its initial silicate mantle, leaving it dominated by its dense iron core. They support this hypothesis with theoretical calculations.
The CfA’s Li Zeng notes: «This is one out of many interesting exoplanet systems that the Kepler space telescope has discovered and characterized. This discovery has confirmed earlier theoretical work suggesting that giant impact between planets has played a role during planet formation. The TESS mission is expected to find more of such examples.»
If catastrophic disruptions occur frequently in planetary systems, then astronomers predict finding many other examples like Kepler-107 as an increasing number of exoplanet densities are determined precisely.
Mercedes Lopez-Morales, Andrew Vanderburg, John Johnson, Dave Latham, Chantanelle Nava, David Phillips and Dimitar Sasselov are other CfA members of the team. Li Zeng is also affiliated with the Harvard Origins of Life Initiative and the Department of Earth & Planetary Sciences.
Headquartered in Cambridge, Mass., the Center for Astrophysics | Harvard & Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

Tyler Jump
Public Affairs
Center for Astrophysics | Harvard & Smithsonian
+1 617-495-7462
tyler.jump@cfa.harvard.edu


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Farmers began transforming diets across the OId World 7,000 years ago, study finds

Since the beginning of archaeology, researchers have combed the globe searching for evidence of the first domesticated crops. Painstakingly extracting charred bits of barley, wheat, millet and rice from the remains of ancient hearths and campfires, they’ve published studies contending that a particular region or country was among the first to bring some ancient grain into cultivation.

Farmers began transforming diets across the OId World 7,000 years ago, study finds
Prehistoric farmers expanded the cultivation of domestic grains into extreme climate regions of the Old World,
such as this barley field in Zuoni County, Gannan Tibetan Autonomous Prefecture
[Credit: Xinyi Liu/Washington University]

Now, an international team of scientists, led by Xinyi Liu of Washington University in St. Louis, has consolidated findings from hundreds of these studies to plot a detailed map of how ancient cereal crops spread from isolated pockets of first cultivation to become dietary staples in civilizations across the Old World.

«The very fact that the ‘food globalization’ in prehistory spanned more than three thousand years indicates perhaps a major driver of the process was the perpetual needs of the poor rather than more ephemeral cultural choices of the powerful in the Neolithic and Bronze Age,» said Liu, assistant professor of anthropology in Arts & Sciences.

Published in the journal Quaternary Science Reviews, the study illustrates the current scientific consensus on the prehistoric food globalization process that transformed diets across Eurasia and Northern Africa between 7,000 and 3,500 years ago.

Co-authors include researchers from the University of Cambridge in the United Kingdom; Zheijiang University in China; the Lithuanian Institute of History; the Smithsonian Institution; and the Chinese Academy of Social Sciences in Beijing.

The study suggests that food globalization in prehistoric times was driven not by exotic appetities of ruling elites, but by the relentless, season-to-season ingenuity of poor peasant farmers looking for new ways to put just a little more food on their tables.

«Recent research developments shift the focus from chronology and routes to the drivers of the ‘food globalization’ process and considers the context in which agricultural and dietary innovations arose and what agents were involved,» Liu said. «These studies emphasize the role played by the primary agents of agricultural production, the ordinary farmers in the past.»

By trying new types of seed, plowing fields a little further up or down the mountain or shifting planting and harvest times, peasant farmers used a trial-and-error approach to overcome climatic challenges and expand the geographic boundaries of where certain grains could be planted. Gradually, this experimentation led to vastly improved yields as farmers learned to extend the growing season by planting both spring and fall crops in the same fields.

Farmers began transforming diets across the OId World 7,000 years ago, study finds
Animation illustrates how four of the ancient world’s most important domesticated grain crops spread
across the Old World between 7,000 and 3,500 years ago [Credit: Data source: Xinyi Liu;
Animation by Javier Ventura/Washington University]

While many people are familiar with the global spread of food crops following the exploration of the New World — a process known as the Columbian Exchange — Liu contends that the prehistoric food globalization process had an equally dramatic impact on food cultivation in the Old World.

Wheat and barley moved from southwest Asia to Europe, India and China, while broom and foxtail millet moved in the other direction: from China to the West. Rice traveled across East, South and Southeast Asia; African millets and sorghum moved across sub-Saharan Africa and across the Indian Ocean, Liu said.

«While much of the exotic foods we enjoy today are the results of modern trade networks, the food globalization process clearly has its roots in prehistory,» Liu said. «Food globalization was well underway before the Columbia Exchange and the Islamic Agricultural Revolution. It predates even the earliest material evidence of trans-Eurasian contact, such as the Silk Route, by millennia.»

Liu’s study traces the farm-to-table journeys of mainstay cereal crops as they criss-crossed continents of the Old World in three distinct waves:

Before 5000 B.C., early farming communities sprang up in isolated pockets of fertile foothills and stream drainage basins where conditions were optimal for cultivating wild grains that originated nearby. Crop dispersals are generally limited to neighboring regions that are broadly compatible in terms of climate and seasonality.

Between 5000 and 2500 B.C., farmers found ways to push cultivation of various grains across wide regions where crop-compatible weather systems were contained within and separated by major mountain systems, such as those associated with the Tibetan Plateau and the Tianshan Mountains.

Between 2500 and 1500 B.C., farmers found ways to move beyond natural and climatic barriers that had long separated east and west, north and south — mastering the cultivation of grains that had evolved to flourish in the extreme elevations of the Tibetan Plateau or the drenching rains of Asian monsoons. Previously isolated agricultural systems were brought together, ushering in a new kind of agriculture in which the planting of both local and exotic crops enables multiple cropping and extended growing seasons.

«The whole process is not only about adoption but also about ‘rejection,’ reflect a range of choices that different communities made, sometimes driven by ecological expediency in novel environments, sometimes by culinary conservatism,» Liu said. «As the old Chinese saying goes: For what has been long united, it will fall apart, and for what has been long divided, it will come together eventually.»

Author: Gerry Everding | Source: Washington University in St Louis [February 05, 2019]

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