[This is maybe the single most fascinating piece of biology research I’ve ready about in years. 2010, so it’s probably old news to some. -egg]
The discovery that ATP synthesis is powered by proton gradients was one of the most counterintuitive in biology. The mechanisms by which proton gradients are formed and coupled to ATP synthesis are known in atomic detail, but the broader question – why are proton gradients central to life? – is still little explored. Recent research suggests that proton gradients are strictly necessary to the origin of life and highlights the geological setting in which natural proton gradients form across membranes, in much the same way they do in cells. But the dependence of life on proton gradients might also have prevented the evolution of life beyond the prokaryotic level of complexity, until the unique chimeric origin of the eukaryotic cell released life from this constraint, enabling the evolution of complexity.
For nearly nine decades, science’s favorite explanation for the origin of life has been the “primordial soup”. This is the idea that life began from a series of chemical reactions in a warm pond on Earth’s surface, triggered by an external energy source such as lightning strike or ultraviolet (UV) light. But recent research adds weight to an alternative idea, that life arose deep in the ocean within warm, rocky structures called hydrothermal vents.
A study published last month in Nature Microbiology suggests the last common ancestor of all living cells fed on hydrogen gas in a hot iron-rich environment, much like that within the vents. Advocates of the conventional theory have been sceptical that these findings should change our view of the origins of life. But the hydrothermal vent hypothesis, which is often described as exotic and controversial, explains how living cells evolved the ability to obtain energy, in a way that just wouldn’t have been possible in a primordial soup.
Under the conventional theory, life supposedly began when lightning or UV rays caused simple molecules to join together into more complex compounds. This culminated in the creation of information-storing molecules similar to our own DNA, housed within the protective bubbles of primitive cells. Laboratory experiments confirm that trace amounts of molecular building blocks that make up proteins and information-storing molecules can indeed be created under these conditions. For many, the primordial soup has become the most plausible environment for the origin of first living cells.
But life isn’t just about replicating information stored within DNA. All living things have to reproduce in order to survive, but replicating the DNA, assembling new proteins and building cells from scratch require tremendous amounts of energy. At the core of life are the mechanisms of obtaining energy from the environment, storing and continuously channelling it into cells’ key metabolic reactions.
Where this energy comes from and how it gets there can tell us a whole lot about the universal principles governing life’s evolution and origin. Recent studies increasingly suggest that the primordial soup was not the right kind of environment to drive the energetics of the first living cells.
It’s classic textbook knowledge that all life on Earth is powered by energy supplied by the sun and captured by plants, or extracted from simple compounds such as hydrogen or methane. Far less known is the fact that all life harnesses this energy in the same and quite peculiar way.
This process works a bit like a hydroelectric dam. Instead of directly powering their core metabolic reactions, cells use energy from food to pump protons (positively charged hydrogen atoms) into a reservoir behind a biological membrane. This creates what is known as a “concentration gradient” with a higher concentration of protons on one side of the membrane than other. The protons then flow back through molecular turbines embedded within the membrane, like water flowing through a dam. This generates high-energy compounds that are then used to power the rest of cell’s activities.
Life could have evolved to exploit any of the countless energy sources available on Earth, from heat or electrical discharges to naturally radioactive ores. Instead, all life forms are driven by proton concentration differences across cells’ membranes. This suggests that the earliest living cells harvested energy in a similar way and that life itself arose in an environment in which proton gradients were the most accessible power source.
Vent hypothesis
Recent studies based on sets of genes that were likely to have been present within the first living cells trace the origin of life back to deep-sea hydrothermal vents. These are porous geological structures produced by chemical reactions between solid rock and water. Alkaline fluids from the Earth’s crust flow up the vent towards the more acidic ocean water, creating natural proton concentration differences remarkably similar to those powering all living cells.
The studies suggest that in the earliest stages of life’s evolution, chemical reactions in primitive cells were likely driven by these non-biological proton gradients. Cells then later learned how to produce their own gradients and escaped the vents to colonise the rest of the ocean and eventually the planet.
While proponents of the primordial soup theory argue that electrostatic discharges or the Sun’s ultraviolet radiation drove life’s first chemical reactions, modern life is not powered by any of these volatile energy sources. Instead, at the core of life’s energy production are ion gradients across biological membranes. Nothing even remotely similar could have emerged within the warm ponds of primeval broth on Earth’s surface. In these environments, chemical compounds and charged particles tend to get evenly diluted instead of forming gradients or non-equilibrium states that are so central to life.
Deep-sea hydrothermal vents represent the only known environmentthat could have created complex organic molecules with the same kind of energy-harnessing machinery as modern cells. Seeking the origins of life in the primordial soup made sense when little was known about the universal principles of life’s energetics. But as our knowledge expands, it is time to embrace alternative hypotheses that recognise the importance of the energy flux driving the first biochemical reactions. These theories seamlessly bridge the gap between the energetics of living cells and non-living molecules.
For artist Amy Genser, paper is pigment. The Connecticut-based artist cuts, rolls, and arranges countless tubes of mulberry paper mounted to Masonite boards to produce vibrant reef-like canvases. The tightly rolled papers perfectly mimc the forms of sea coral that appears to grow organically in
[This is the same company — and same approach — that developed the go-playing software that recently beat a leading professional player. -egg]
Alphabet’s DeepMind division reports they improved the overall power usage efficiency (PUE) of Google’s data centers by 15 percent after placing an AI program similar to a program taught to play Atari games in charge of managing a data center’s control systems. DeepMind and data center engineers report they’ve improved the cooling systems PUE consistently by up to 40 percent and that the program had achieved the lowest PUE the data center site had ever seen.
Demis Hassabisnoted that it was not only a cost savings, but also reduced the environmental impact of their data centers. Google reportedly used 4,402,836 MWh of electricity in 2014, or the equivalent of 366,903 U.S family homes according to Google Green. They’ve provided a carbon footprint estimate for serving an active Google user, which is defined as:
someone who does 25 searches and watches 60 minutes of YouTube a day, has a Gmail account and uses our other services, for whom Google emits about 8 grams of CO2 per day to serve. In other words, serving a Google user for a month is like driving a car one mile.
According to an initial report, the offset in cost savings could be hundreds of millions of dollars in savings over multiple years and will in-part, if not completely, pay for the 400 million pound, or more than $600 million DeepMind acquisition. It will also reportedly reduce their data center’s carbon-footprint-per-user. On how the program achieved the efficiency gains, DeepMind research engineer Rich Evans and Google data center engineer Jim Gao stated they:
accomplished this by taking the historical data that had already been collected by thousands of sensors within the data centre, data such as temperatures, power, pump speeds, setpoints, etc. and using it to train an ensemble of deep neural networks… then trained the neural networks on the average future PUE, which is defined as the ratio of the total building energy usage to the IT energy usage. We then trained two additional ensembles of deep neural networks to predict the future temperature and pressure of the data centre over the next hour. The purpose of these predictions is to simulate the recommended actions from the PUE model, to ensure that we do not go beyond any operating constraints.
Individual data center characteristics like climate and weather, each center’s unique site-specific architecture, and the interplay between different systems throughout the day had previously made creating a universal equation for optimizing PUE not possible. With the deep learning, convolutional neural network approach a single equation isn’t necessary because the program can learn to play in a game-like manner from the inputs being fed in from sensors and a reference to ideal outcomes. The engineers demonstrated how the PUE was affected for the site when the program was turned on and off. Hassabis said they had learned where gaps in their data center data capture were and that additional sensors would be deployed to further increase efficiency.
According to DeepMind, the same technology could potentially be used to improve power plant conversion efficiency, reducing semiconductor manufacturing and water usage, or helping manufacturing facilities increase throughput.
[George F. Will being surprisingly reasonable. -egg]
The second fallacy behind a passive judiciary deferring to majoritarian institutions is more fundamental. It is rooted in the fact that we know, because he said so, clearly and often, that Lincoln took his political bearings from the Declaration of Independence. We know that Lincoln believed, because the Declaration says so, that governments are instituted to secure our natural rights. These rights therefore pre-exist government. And they include the unenumerated ones affirmed in the Constitution’s Ninth Amendment: “The enumeration in the Constitution of certain rights shall not be construed to deny or disparage others retained by the people.”
…
For many years and for several reasons, many of my fellow conservatives have unreflectively and imprudently celebrated “judicial restraint.” For many years, I, too, was guilty of this. The reasons for that celebration of restraint include an understandable disapproval of some of the more freewheeling constitutional improvisations of the Warren Court, and the reasonable belief that the law schools that train future judges, and the law reviews that influence current judges, are, on balance, not balanced — that they give short shrift to conservatism. It is, however, high time for conservatives to rethink what they should believe about the role of courts in the American regime.
Another reason many conservatives favor judicial deference and restraint is what can be called the conservative populist temptation. Conservatives are hardly immune to the temptation to pander — to preach that majorities are presumptively virtuous and that the things legislatures do are necessarily right because they reflect the will of the majority.
But the essential drama of democracy derives from the inherent tension between the natural rights of the individual and the constructed right of the community to make such laws as the majority deems necessary and proper.
Associated Press: It’s one of the most universal recommendations in all of public health: Floss daily to prevent gum disease and cavities.Except there’s little proof that flossing works.
Still, the federal government, dental organizations and manufacturers of floss have pushed the practice for decades. Dentists provide samples to their patients; the American Dental Association insists on its website that, “Flossing is an essential part of taking care of your teeth and gums.”
The federal government has recommended flossing since 1979, first in a surgeon general’s report and later in the Dietary Guidelines for Americans issued every five years. The guidelines must be based on scientific evidence, under the law.
Last year, the Associated Press asked the departments of Health and Human Services and Agriculture for their evidence, and followed up with written requests under the Freedom of Information Act.
When the federal government issued its latest dietary guidelines this year, the flossing recommendation had been removed, without notice. In a letter to the AP, the government acknowledged the effectiveness of flossing had never been researched, as required.
