Science Sunday #18
Posted by Don McLenaghen on October 17, 2011
– and on the seventh day we learn.
Each week I hope to give a synopsis of the interesting science stories I have heard on my plethora of science podcasts I listen to each week plus anything I pick up scanning the inter-web. This week’s top stories:
Words of the Week:
Glaciation – an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. interglacial, on the other hand, are periods of warmer climate within an ice age. The last glacial period ended about 15,000 years ago; The Holocene epoch is the current interglacial.
Ochre – the term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as “red ochre”. The more rarely used terms “purple ochre” and “brown ochre” also exist for variant hues. Because of these other hues, the color ochre is sometimes referred to as “yellow ochre” or “gold ochre”.
Ochres are among the earliest pigments used by mankind, derived from naturally tinted clay containing mineral oxides. Chemically, it is hydrated iron (III) oxide. Modern artists’ pigments continue to use the terms “yellow ochre” and “red ochre” for specific hues.
Geologic time scale – provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth. The table of geologic time spans presented here agrees with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geological Survey. The terms eonothem, erathem, system, series, and stage are used to refer to the layers of rock that correspond to these periods of geologic time. The definitions tend to be ‘arbitrary’ and circular; that is a rock layer is defined by the length of time it took to occur, while a length of time is defined by how long a rock layer took to form. Each of the following is in descending order of length of time.
- Super-eon – All the eons, essentially all time on earth.
- Eon – Largest unit of time – 4 total, half a billion years or more – eonothem
- Era – a major division of geological time – 12 total, several hundred million years – erathem
- Period – a subdivision of the geologic timescale based on rock layering – System
- Epoch – tens of millions of years – Series
- Age – millions of years – Stage
- Chron – a slice of time that begins at a given identifiable event and ends at another. In the fossil record such tracer events are usually keyed to disappearance (extinction) of a widely distributed and rapidly changing species or the appearance of such a species in the geological record. – Chronozone
Holocene – a geological epoch which began at the end of the Pleistocene  (around 10,000 14C years ago) and continues to the present. The Holocene is part of the Quaternary period.
It has been identified with the current warm period, known as MIS 1 and based on that past evidence, can be considered an interglacial in the current ice age.
This week’s top stories:
Machine, heal thy self! –
Scientists at Northwestern University have developed a new nanomaterial that can “steer” electrical currents. The development could lead to a computer that can simply reconfigure its internal wiring and become an entirely different device, based on changing needs.
“Our new steering technology allows use to direct current flow through a piece of continuous material,” said Bartosz A. Grzybowski, who led the research. “Like redirecting a river, streams of electrons can be steered in multiple directions through a block of the material — even multiple streams flowing in opposing directions at the same time.”
The Northwestern material combines different aspects of silicon- and polymer-based electronics to create a new classification of electronic materials: nanoparticle-based electronics.
The hybrid material is composed of electrically conductive particles, each five nanometers in width, coated with a special positively charged chemical. The particles are surrounded by a sea of negatively charged atoms. By applying an electrical charge across the material, the small negative atoms can be moved and reconfigured, but the relatively larger positive particles are not able to move.
By moving this sea of negative atoms around the material, regions of low and high conductance can be modulated; the result is the creation of a directed path that allows electrons to flow through the material. Old paths can be erased and new paths created by pushing and pulling the sea of negative atoms. More complex electrical components, such as diodes and transistors, can be made when multiple types of nanoparticles are used.
Imagine a single device that reconfigures itself into a resistor, a rectifier, a diode and a transistor based on signals from a computer. The multi-dimensional circuitry could be reconfigured into new electronic circuits using a varied input sequence of electrical pulses.
Escaping Snowball Earth –
Earth has experienced several extreme glacial events, two of which took place during the aptly named Cryogenian period (710-630 million years ago). In 1992 and 1998 scientists hypothesized that around 635 million years ago our planet underwent a major glacial episode that left it entirely smothered in ice. Today still, the question of how this episode came to an end remains unanswered, given that ice reflects more solar radiation back into space than rocks do.
In the Snowball Earth hypothesis, it is assumed that enough CO2 of volcanic origin had built up in the atmosphere for this greenhouse gas to warm up the surface of the planet and cause the ice to melt. According to this scenario, CO2 concentrations must have fluctuated around 120,000 ppmv — i.e.,12%, which is 300 times greater than CO2 concentrations today.
This mechanism for ending the snowball earth seems to has been given a blow. A paper to be published in Nature, reports that nowhere near enough CO2 was available to end the extended period of glaciation.
In order to assess the atmospheric concentration of CO2 at that time, the French, Brazilian and US researchers studied carbonates deposited 635 million years ago (the Marinoan glaciation). These sediments cap the glacial deposits of that period, believed to have witnessed a global glaciation known as Snowball Earth.
The study is based on the difference in carbon isotopic composition between carbonates and organic matter in fossilized organisms, which reflects atmospheric concentrations of CO2. The results show that CO2 concentrations were very close to what they are today (less than 3,200 ppmv), which is far from being sufficient to bring about the end of a glacial episode of this magnitude.
Choice in healthcare not so good –
Research which claims to show that the introduction of patient choice in the United Kingdom’s National Health Service (NHS) reduced deaths from heart attacks is flawed and misleading, according to a report published in The Lancet.
The original study was used by the Government to advance its controversial Health and Social Care Bill 2011 and was the basis for the Prime Minister’s statement that ‘competition is one way we can make things work better for patients’. The study examined the mortality rates for heart attack patients measured against the number of hospitals within travelling distance of the patient’s GP surgery. It also looked at data on elective surgery for hernia, cataract repair, knee arthroscopy, hip replacement and knee replacement, and claims to show that introducing greater choice in elective surgery led to lower death rates from heart attacks.
In the report, academics — led by Professor Allyson Pollock of Queen Mary, University of London — point out a series of errors in the study and conclude that it is ‘fundamentally flawed’.
A primary complaint as the study offers no explanation as to why the availability of choice for such elective procedures should have any effect on whether heart attack patients survive.
The Lancet report also points out the following:
- The researchers do not look at whether the availability of choice has any effect on where patients go for treatment,
- They do not look at whether or how GPs’ patterns of referrals changed when choice became available,
- Recent research indicates the majority of patients who have been offered a choice pick their nearest hospital,
- Heart attack is a medical emergency and patients generally have no choice about where they are treated,
- Outcomes for heart attack patients tend to be better when they are treated in specialist centres in urban areas,
- The authors ignore the possible effects of major changes in primary care prevention and secondary care intervention for heart attacks,
- That there is no evidence that the data on elective operations is in any way a good measure of choice or competition.
Professor Pollock said: “The Government’s Health Bill has faced enormous opposition from the public and from health professionals. In trying to win over his critics the Prime Minister has used the study by Zack Cooper to justify competition within the National Health Service.
“Our examination of this research reveals it to be fundamentally flawed, amounting to the conclusion that the paper simply doesn’t prove either cause or effect between patient choice and death rates.
“This work should not be quoted as scientific evidence to support choice, competition or the new Health and Social Care Bill.”
The birth place of art? –
An ochre-rich mixture, possibly used for decoration, painting and skin protection 100,000 years ago, and stored in two abalone shells, was discovered at Blombos Cave in Cape Town, South Africa. The earliest previous example of early art dates back to cave painting in France dating to 35,000 bc.
“Ochre may have been applied with symbolic intent as decoration on bodies and clothing during the Middle Stone Age,” says Professor Christopher Henshilwood who helped discover a processing workshop in 2008 where a liquefied ochre-rich mixture was produced.
The findings will be published By Henshilwood et al in the prestigious international journal Science, on Friday, 14 October 2011.
The two coeval, spatially associated toolkits were discovered in situ (not been moved from its original place of deposition) and the kits included ochre, bone, charcoal, grindstones and hammerstones. The grinding and scraping of ochre to produce a powder for use as a pigment was common practice in Africa and the Near East only after about 100,000 years ago.
“This discovery represents an important benchmark in the evolution of complex human cognition (mental processes) in that it shows that humans had the conceptual ability to source, combine and store substances that were then possibly used to enhance their social practices,” explains Henshilwood.
I should note, in the Quirks and Quarks interview, mention was made that some archeologist have been investigating the use of Ochre on arrowheads. Apparently the application of the paste makes an arrow/spearhead more likely to remain embedded (and thus more lethal); and that this practical use was the original use of Ochre. As such, it is possible this discovery was not evidence of ‘complex human cognition’ but an improvement of weapons technology (which of course could have helped lead to ‘complex human cognition’ by provided a material for art)
A new geological age, and it OUR fault! –
A new term has been coined to express the vast and dramatic impact humanity has had on the planet Earth itself on a global, environmental and geological scale. This term is Anthropocene. The term was coined by ecologist Eugene Stoermer but has been widely popularized by the Nobel Prize-winning atmospheric chemist Paul Crutzen, who regards the influence of human behavior on the Earth’s atmosphere in recent centuries as so significant as to constitute a new geological era for its lithosphere.
Geological Society of America titled its 2011 annual meeting: Archean to Anthropocene: The past is the key to the future. The Anthropocene has no precise start date, but based on atmospheric evidence may be considered to start with the Industrial Revolution (late 18th century). Other scientists link it to earlier events, such as the rise of agriculture.
Evidence of relative human impact such as the growing human influence on land use, ecosystems, biodiversity and species extinction is controversial, some scientists believe the human impact has significantly changed (or halted) the growth of biodiversity.
The Anthropocene may have begun as early as 14,000 to 15,000 years before present, based on lithospheric evidence; this has led other scientists to suggest that “the onset of the Anthropocene should be extended back many thousand years”; this would be closely synchronous with the current term, Holocene.
Antarctic’s hidden lakes to be explored! –
Explorers depart next week for Antarctica on the first stage of an ambitious scientific mission to collect water and sediment samples from the sub-glacial Lake Ellsworth on the West Antarctic Ice Sheet buried beneath 1.8 miles (3 kilometers) of solid ice. This mission will hopefully yield new knowledge about the evolution of life on Earth and other planets, and will provide vital clues about the Earth’s past climate.
Lake Ellsworth is likely to be the first of Antarctica’s sub-glacial lakes to be measured and sampled directly through the design and manufacture of space-industry standard “clean technology,”
Antarctica is home to 387 known sub-glacial lakes, some of the most pristine environments on Earth. Lake Vostok in East Antarctica is the most well-known of these lakes. A Russian team has been trying to drill and collect samples from Vostok, but were unable to do so before winter set in this year.
David Pearce, science coordinator at the British Antarctic Survey “Finding life in a lake that could have been isolated from the rest of the biosphere for up to half a million years will tell us so much about the potential origin of and constraints for life on Earth, and may provide clues to the evolution of life on other extraterrestrial environments. If we find nothing, this will be even more significant because it will define limits at which life can no longer exist on the planet.”
This technology is also important because it can act as test runs for interplanetary exploration for life on Europa, Enceladus and other frozen water worlds.