bluuebunny/crossref_metadata_2025 huggingface dataset:
An empirical study of Taiwan’s food security index
Authors: Yeh Chih-Yang , Liao Pei-San , Liu Chieh-Yu , Liu Jeng-Fu , Chang Hsing-Yi
Published: October 2009

Objective

The FAO has developed an approach for estimating the prevalence of undernourishment. Based on the FAO method Taiwan has a prevalence of undernourishment of 3·98 %, which is higher than that of some developing countries. As this is not a true reflection of the status of undernourishment in our nation, the purpose of the present study was to modify the FAO methodology for Taiwan.

Design

Two factors were considered in the modified version. As the minimum dietary energy requirement was the main factor contributing to the inflated prevalence in Taiwan, we adjusted for a lighter physical activity level, based on the average BMI of the Taiwanese population, and calculated a new minimum dietary energy requirement. We then fitted a second-order polynomial regression model for prediction of per capita dietary energy supply.

Results

The adjusted minimum dietary energy requirement was reduced to 7648 kJ/d or 7765 kJ/d compared with the original value of 8054 kJ/d. This resulted in a decrease of the prevalence of undernourishment in Taiwan to 2·5 % or 3·0 %, which is much closer to that of other countries with the same level of economic development. The second-order polynomial regression model efficiently reduced the variation in dietary energy consumption and resulted in an undernourishment prevalence of less than 2·5 %.

Conclusions

This new adapted method is more appropriate for Taiwan. It is recommended that each country evaluates the appropriateness of the FAO approach for its population.
Fate determination of adult human glial progenitor cells
Authors: Sim Fraser J. , Windrem Martha S. , Goldman Steven A.
Published: October 2009

Glial progenitor cells (GPCs) comprise the most abundant population of progenitor cells in the adult human brain. They are responsible for central nervous system (CNS) remyelination, and likely contribute to the astrogliotic response to brain injury and degeneration as well. Adult human GPCs are biased to differentiate as oligodendrocytes and elaborate new myelin, and yet they retain multilineage plasticity, and can give rise to neurons as well as astrocytes and oligodendrocytes once removed from the adult parenchymal environment. GPCs retain strong mechanisms for cell-autonomous self-renewal, and yet both their phenotype and fate may be dictated by their microenvironment. Using the transcriptional profiles of acutely isolated GPCs, we have begun to understand the operative ligand–receptor interactions involved in these processes, and have identified several key signaling pathways by which adult human GPCs may be reliably instructed to either oligodendrocytic or astrocytic fate. In addition, we have noted significant differences between the expressed genes and dominant signaling pathways of fetal and adult human GPCs, as well as between rodent and human GPCs. The latter data in particular call into question therapeutic strategies predicated solely upon data obtained using rodents, while perhaps highlighting the extent to which evolution has been attended by the phylogenetic modification of glial phenotype and function.
Osteoporose: Diagnostische Aspekte und Frakturrisikoevaluation
Authors: Meier
Published: October 2009

Die klinische Bedeutung der Osteoporose ergibt sich aus den Komplikationen, den osteoporotischen Frakturen. Hauptrisikofaktoren und damit Begründung für eine weiterführende Diagnostik sind bereits erlittene nicht-traumatische vertebrale oder nicht-vertebrale Frakturen, eine Langzeittherapie mit Glukokortikoiden, ein geringes Körpergewicht, ein erhöhtes Sturzrisiko sowie Krankheiten, die mit einem erhöhten Frakturrisiko einhergehen. Bei der Interpretation der Densitometrieresultate muss unterschieden werden zwischen der diagnostischen Schwelle (WHO-Definition der Osteoporose: T-Score ≤–2.5) und der Interventionsschwelle. Die Indikation zur Behandlung der Osteoporose stützt sich auf das individuelle Frakturrisiko (integrale Beurteilung verschiedener Risikofaktoren wie fortgeschrittenes Alter, erniedrigte Knochendichte, Knochenumbaurate und Vorliegen nicht-traumatischer Frakturen) und sollte nicht nur auf einem einzelnen Knochendichtewert abgestützt werden.
Retrogressive failures recorded in mass transport deposits in the Ursa Basin, Northern Gulf of Mexico
Authors: Sawyer Derek E. , Flemings Peter B. , Dugan Brandon , Germaine John T.
Published: October 2009

Clay‐rich mass transport deposits (MTDs) in the Ursa Basin, Gulf of Mexico, record failures that mobilized along extensional failure planes and transformed into long runout flows. Failure proceeded retrogressively: scarp formation unloaded adjacent sediment causing extensional failure that drove successive scarp formation updip. This model is developed from three‐dimensional seismic reflection data, core and log data from Integrated Ocean Drilling Project (IODP) Expedition 308, and triaxial shear experiments. MTDs are imaged seismically as low‐amplitude zones above continuous, grooved, high‐amplitude basal reflections and are characterized by two seismic facies. A Chaotic facies typifies the downdip interior, and a Discontinuous Stratified facies typifies the headwalls/sidewalls. The Chaotic facies contains discontinuous, high‐amplitude reflections that correspond to flow‐like features in amplitude maps: it has higher bulk density, resistivity, and shear strength, than bounding sediment. In contrast, the Discontinuous Stratified facies contains relatively dim reflections that abut against intact pinnacles of parallel‐stratified reflections: it has only slightly higher bulk density, resistivity, and shear strength than bounding sediment, and deformation is limited. In both facies, densification is greatest at the base, resulting in a strong basal reflection. Undrained shear tests document strain weakening (sensitivity = 3). We estimate that failure at 30 meters below seafloor will occur when overpressure = 70% of the hydrostatic effective stress: under these conditions soil will liquefy and result in long runout flows.
Precipitation and temperature statistics in high‐resolution regional climate models: Evaluation for the European Alps
Authors: Smiatek G. , Kunstmann H. , Knoche R. , Marx A.
Published: October 2009

In this study, high‐resolution climate change data from the regional climate models COSMO‐CLM, HIRHAM, RegCM, and REMO were evaluated in the Greater Alpine Region (GAR; 4°W–19°W and 43°N–49°N) and three additional subareas of 1.5° by 1° in size. Evaluation statistics include mean temperature and precipitation, frequency of days with precipitation over 1 mm and over 15 mm, 90% quantile of the frequency distribution, and maximum number of consecutive dry days. The evaluation for the 1961–1990 period indicates that the models reproduce spatial precipitation patterns and the annual cycle. The mean precipitation domain bias varies between 11% and 40% in winter season and between −14.5% and 11% in summer. Larger errors are found for other statistics and in the various regions. No single best model could be identified comparing modeled precipitation characteristics with observational reference. The study shows that there is still high uncertainty in the expected climate change. Furthermore, future temperature and precipitation changes simulated with different SRES scenarios and calculated by different RCMs overlap. The temperature calculations for the period 2071–2100 related to the period 1961–1990 in the GAR area show an increase in the monthly mean 2m temperature of up to 4.8 K in summer. In the GAR area, a precipitation decrease of up to 29% in summer and precipitation increase of approximately 20% in the winter season is simulated. Summer and autumn temperatures are expected to increase more than winter and spring temperatures. Detailed analysis reveals that the different regional climate model runs based on different regional models, different driving global models and different emission scenarios show similar trends, but differ in the magnitude of the expected climate change signal. All models seem to agree on the increased frequency of high‐precipitation events in the winter season.
Deciphering Earth's Deep History: Drilling in Africa's Oldest Greenstone Belt
Authors: Grosch Eugene G. , McLoughlin Nicola , de Wit Maarten , Furnes Harald
Published: October 2009

Earth's early evolution and the conditions under which life first emerged are highly controversial topics. Did Venus‐type tectonics dominate the early Earth, with vast landscapes of hot spot volcanoes belching lava and gases into a tenuous carbon dioxide/methane‐rich atmosphere, or was plate tectonics already in operation? Debates rage about when water first became dominant across Earth's surface, the temperatures and depths of early oceans, and when the first protocontinents began to form. These large uncertainties confound scientists' understanding of ecological niches available for the emergence of simple life, and a quantifiable image of the early Archean world is still missing.
Geoscientists Flock to Capitol Hill for Congressional Visits Day
Authors: Chell Kaitlin
Published: October 2009

The second annual Geosciences Congressional Visits Day (Geo‐CVD), on 15–16 September 2009, came at a time when the U.S. Congress is considering a number of issues intimately connected to the geosciences, including energy, the environment, and climate. Nearly 60 geoscientists from across the country, including 22 AGU members from 12 states, participated in this year's event by discussing geoscience issues with members of Congress and their staffs. AGU cosponsored the event along with nine other Earth and space science societies that work together on geoscience policy issues as part of the Geopolicy Working Group in Washington, D.C.

Geo‐CVD kicked off with the U.S. Geological Survey (USGS) Coalition's annual reception on Capitol Hill on 14 September. AGU is a member of the USGS Coalition, which includes several other science societies, and this year AGU organized the reception together with the Seismological Society of America. At the reception, U.S. senators Dianne Feinstein (D‐Calif.) and Lisa Murkowski (R‐Alaska) received the coalition's annual Leadership Award in recognition of their continuing commitment to USGS. Sen. Feinstein chairs the Senate Appropriations Subcommittee on Interior, Environment, and Related Issues, which is tasked with allocating funds to USGS; Sen. Murkowski is the ranking member on the Senate Committee on Energy and Natural Resources.
Distinct causes for two principal U.S. droughts of the 20th century
Authors: Hoerling Martin , Quan Xiao‐Wei , Eischeid Jon
Published: October 2009

Diagnosis of observational and climate model data reveals that the two major U.S. droughts of the 20th Century had distinct causes. Drought severity over the Southern Plains during 1946–1956 is very likely attributable to remote influences of global sea surface temperatures (SSTs). The Southern Plains and adjacent Southwest are regions particularly sensitive to SST variability, and strong La Niña events that occurred during 1946–1956 exposed that region's drought vulnerability. Drought severity over the Northern Plains during 1932–1939 was likely triggered instead by random atmospheric variability. The Northern Plains lies within a region of comparatively low sensitivity to SST variability, and that region's drought exhibited little sensitivity to SST conditions during the Dust Bowl period. Our results indicate that the southern portions of the Great Plains lie within an epicenter of potentially skillful drought predictions for which an ocean observing system is also a vital drought early warning system.
Direct observations of N2O5 reactivity on ambient aerosol particles
Authors: Bertram Timothy H. , Thornton Joel A. , Riedel Theran P. , Middlebrook Ann M. , Bahreini Roya , Bates Timothy S. , Quinn Patricia K. , Coffman Derek J.
Published: October 2009

N2O5 reactivity has been measured directly for the first time on ambient aerosol particles using an entrained aerosol flow reactor coupled to a custom‐built chemical ionization mass spectrometer at two urban locations during summer. The observed N2O5 reactivity is a strong function of both relative humidity (RH) and particle chemical composition. We show that particulate organic mass loadings, together with ambient relative humidity, play a leading role in determining the reaction rate of N2O5 with particles. Our observed reactivity values are both more variable and, at times, as much as a factor of ten lower than currently implemented large‐scale model parameterizations would predict. Such discrepancies have likely consequences for predictions of NOx availability and ozone production, and the sensitivity of these quantities to aerosol particle loadings.
Dicarboxylic acids and water‐soluble organic carbon in aerosols in New Delhi, India, in winter: Characteristics and formation processes
Authors: Miyazaki Yuzo , Aggarwal Shankar G. , Singh Khem , Gupta Prabhat K. , Kawamura Kimitaka
Published: October 2009

Day‐ and nighttime aerosol samples were collected at an urban site in New Delhi, India, in winter 2006–2007. They were studied for low molecular weight dicarboxylic acids and related compounds, as well as total water‐soluble organic carbon (TWSOC). High concentrations of diacids (up to 6.03 μg m−3), TWSOC, and OC were obtained, which are substantially higher than those previously observed at other urban sites in Asia. Daytime TWSOC/OC ratio (37%) was on average higher than that in nighttime (25%). In particular, more water‐soluble OC (M‐WSOC) to TWSOC ratio in daytime (50%) was twice higher than in nighttime (27%), suggesting that aerosols in New Delhi are photochemically more processed in daytime to result in more water‐soluble organic compounds. Oxalic acid (C2) was found as the most abundant dicarboxylic acid, followed by succinic (C4) and malonic (C3) acids. Contributions of C2 to M‐WSOC were greater (av. 8%) in nighttime than daytime (av. 3%). Positive correlations of C2 with malic acid (hC4), glyoxylic acid (ωC2), and relative humidity suggest that secondary production of C2 probably in aqueous phase is important in nighttime via the oxidation of both longer‐chain diacids and ωC2. C2 also showed a positive correlation with potassium (K+) in nighttime, suggesting that the enhanced C2 concentrations are associated with biomass/biofuel burning. More tight, positive correlation between less water‐soluble OC (L‐WSOC) and K+ was found in both day‐ and nighttime, suggesting that L‐WSOC, characterized by longer chain and/or higher molecular weight compounds, is significantly influenced by primary emissions from biomass/biofuel burning.
Traumatic Brain Injury: An Overview of Pathobiology with Emphasis on Military Populations
Authors: Cernak Ibolja , Noble-Haeusslein Linda J
Published: October 2009

This review considers the pathobiology of non-impact blast-induced neurotrauma (BINT). The pathobiology of traumatic brain injury (TBI) has been historically studied in experimental models mimicking features seen in the civilian population. These brain injuries are characterized by primary damage to both gray and white matter and subsequent evolution of secondary pathogenic events at the cellular, biochemical, and molecular levels, which collectively mediate widespread neurodegeneration. An emerging field of research addresses brain injuries related to the military, in particular blast-induced brain injuries. What is clear from the effort to date is that the pathobiology of military TBIs, particularly BINT, has characteristics not seen in other types of brain injury, despite similar secondary injury cascades. The pathobiology of primary BINT is extremely complex. It comprises systemic, local, and cerebral responses interacting and often occurring in parallel. Activation of the autonomous nervous system, sudden pressure-increase in vital organs such as lungs and liver, and activation of neuroendocrine-immune system are among the most important mechanisms significantly contributing to molecular changes and cascading injury mechanisms in the brain.
Arterial Spin Labeling Perfusion MRI at Multiple Delay Times: A Correlative Study with H215O Positron Emission Tomography in Patients with Symptomatic Carotid Artery Occlusion
Authors: Bokkers Reinoud PH , Bremmer Jochem P , van Berckel Bart NM , Lammertsma Adriaan A , Hendrikse Jeroen , Pluim Josien PW , Kappelle L Jaap , Boellaard Ronald , Klijn Catharina JM
Published: October 2009

Arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) with image acquisition at multiple inversion times is a noninvasive ASL technique able to compensate for spatial heterogeneities in transit times caused by collateral blood flow in patients with severe stenosis of the cerebropetal blood vessels. Our aim was to compare ASL-MRI and H215O positron emission tomography (PET), the gold standard for cerebral blood flow (CBF) assessment, in patients with a symptomatic internal carotid artery (ICA) occlusion. Fourteen patients (63±14 years) with a symptomatic ICA occlusion underwent both ASL-MRI and H215O PET. The ASL-MRI was performed using a pulsed STAR labeling technique at multiple inversion times within 7 days of the PET. The CBF was measured in the gray-matter of the anterior, middle and posterior cerebral artery, and white-matter. Both PET and ASL-MRI showed a significantly decreased CBF in the gray-matter of the middle cerebral artery in the hemisphere ipsilateral to the ICA occlusion. The average gray-matter CBF measured with ASL-MRI (71.8±4.3 mL/min/100 g) was higher ( P<0.01) than measured with H215O PET (43.1±1.0 mL/min/100 g). In conclusion, ASL-MRI at multiple TIs is capable of depicting areas of regions with low CBF in patients with an occlusion of the ICA, although a systematic overestimation of CBF relative to H215O PET was noted.
Acetazolamide-Induced Vasodilation Does Not Inhibit the Visually Evoked Flow Response
Authors: Yonai Yaniv , Boms Neta , Molnar Sandor , Rosengarten Bernhard , Bornstein Natan M , Csiba Laszlo , Olah Laszlo
Published: October 2009

Different methods are used to assess the vasodilator ability of cerebral blood vessels; however, the exact mechanism of cerebral vasodilation, induced by different stimuli, is not entirely known. Our aim was to investigate whether the potent vasodilator agent, acetazolamide (AZ), inhibits the neurovascular coupling, which also requires vasodilation. Therefore, visually evoked flow parameters were examined by transcranial Doppler in ten healthy subjects before and after AZ administration. Pulsatility index and peak systolic flow velocity changes, evoked by visual stimulus, were recorded in the posterior cerebral arteries before and after intravenous administration of 15 mg/kg AZ. Repeated-measures ANOVA did not show significant group main effect between the visually evoked relative flow velocity time courses before and after AZ provocation ( P=0.43). Visual stimulation induced significant increase of relative flow velocity and decrease of pulsatility index not only before but also at the maximal effect of AZ. These results suggest that maximal cerebral vasodilation cannot be determined by the clinically accepted dose of AZ (15 mg/kg) and prove that neurovascular coupling remains preserved despite AZ-induced vasodilation. Our observation indicates independent regulation of vasodilation during neurovascular coupling, allowing the adaptation of cerebral blood flow according to neuronal activity even if other processes require significant vasodilation.
Cilostazol, a Phosphodiesterase Inhibitor, Attenuates Photothrombotic Focal Ischemic Brain Injury in Hypertensive Rats
Authors: Ito Hideki , Hashimoto Ayako , Matsumoto Yutaka , Yao Hiroshi , Miyakoda Goro
Published: October 2009

The aim of this study was to evaluate and compare the effects of anti-platelet agents with different modes of action (cilostazol, aspirin, and clopidogrel) on brain infarction produced by photothrombotic middle-cerebral-artery (MCA) occlusion in male, spontaneously hypertensive rats. Cerebral blood flow (CBF) was measured with laser-Doppler flowmetry in the penumbral cortex. Infarct size was evaluated 24 h after MCA occlusion. The effects of these drugs on infarct size were examined by pretreatment of rats undergoing MCA occlusion. Pretreatment with cilostazol (100 mg/kg) significantly reduced infarct size. In contrast, aspirin (10 mg/kg) and clopidogrel (3 mg/kg) failed to mitigate infarct size, regardless of their apparent inhibitory effects on platelet aggregation. Post-treatment with cilostazol also significantly attenuated the infarct size, associated with improved CBF in the penumbral region. In support of this effect, cilostazol increased nitric oxide (NO) production and prostaglandin-I2 (PGI2) release in cultured human brain microvascular endothelial cells. Cilostazol-induced NO production and PGI2 release were completely abolished by an NO synthase inhibitor and aspirin, respectively. These findings show that cilostazol reduced brain infarct size due to an improvement in penumbral CBF possibly in association with increased endothelial NO and PGI2 production.
Coactosin-like protein functions as a stabilizing chaperone for 5-lipoxygenase: role of tryptophan 102
Authors: Esser Julia , Rakonjac Marija , Hofmann Bettina , Fischer Lutz , Provost Patrick , Schneider Gisbert , Steinhilber Dieter , Samuelsson Bengt , Rådmark Olof
Published: October 2009

The activity of 5-LO (5-lipoxygenase), which catalyses two initial steps in the biosynthesis of pro-inflammatory LTs (leukotrienes), is strictly regulated. One recently discovered factor, CLP (coactosin-like protein), binds 5-LO and promotes LT formation. In the present paper we report that CLP also stabilizes 5-LO and prevents non-turnover inactivation of the enzyme in vitro. Mutagenesis of tryptophan residues in the 5-LO β-sandwich showed that 5-LO-Trp102 is essential for binding to CLP, and for CLP to support 5-LO activity. In addition, the stabilizing effect also depended on binding between CLP and 5-LO. After mutations which prevent interaction (5-LO-W102A or CLP-K131A), the protective effect of CLP was absent. A calculated 5-LO–CLP docking model indicates that CLP may bind to additional residues in both domains of 5-LO, thus possibly stabilizing the 5-LO structure. To obtain further support for binding between CLP and 5-LO in a living cell, subcellular localization of CLP and 5-LO in the monocytic cell line Mono Mac 6 was determined. In these cells, 5-LO associates with a nuclear fraction only when differentiated cells are primed with phorbol ester and stimulated with ionophore. The same pattern of redistribution was found for CLP, indicating that the two proteins associate with the nucleus in a co-ordinated fashion. The results of the present study support a role for CLP as a chaperoning scaffold factor, influencing both the stability and the activity of 5-LO.
Basic Techniques in Autogenous Microtia Repair
Authors: Siegert Ralf , Weerda Hilko , Magritz Ralph , Siegert Ralf
Published: October 2009

Although several techniques can be used for microtia repair, some standard procedures have been developed over the past few decades. In specialized centers, these techniques are performed most frequently. They include two to four operative steps using autogenous rib cartilage for the framework and local skin for its tegument. We have been using this technique presented here in more than 800 cases over the past two decades with good and mostly stable results.
A look at the future of particle physics
Authors: Levi Barbara G.
Published: October 2009

US particle physicists have recently been debating where they will find the most exciting physics and what future facilities will best enable them to pursue it. The dialog intensified last summer at a study sponsored by the American Physical Society Division of Particles and Fields and continued through the Division's annual meeting at the University of Maryland at the end of October. About 150 high-energy physicists participated in the DPF Summer Study on Particle Physics and Future Facilities, which was held in Snowmass, Colorado (near Aspen), from 28 June to 16 July. Its stated purpose was to assess the physics topics that might be interesting in the future, to explore the limits of technological capabilities and to consider the nature of future facilities for particle physics in the US. Charles Baltay (Columbia University), chairman of the organizing committee, stressed to us that the role of the summer session was to study the physics but not to arrive at any specific conclusions.
Theory points to pulsating white dwarfs
Authors: Helfand David
Published: October 2009

Astronomy is, in a fundamental sense, an observational science. Unlike some areas of modern physics, for example, where theoretical developments are often the driving force behind experimental progress, new discoveries in astronomy most often spring from new instrumentation for the observer; theoretical predictions of yet-to-be observed phenomena are rare.
The Nuclear Freeze: The freeze and the counterforce race
Authors: Feiveson Harold , von Hippel Frank
Published: October 2009

President Carter, in a 1980 report to Congress, speculated on how the Soviet Union might respond to the deployment of US weapons capable of destroying Soviet missiles in their silos:

“…adopting a launch-on-warning posture is perhaps the least expensive but the most potentially destabilizing and dangerous response option available to Soviet leaders.”
Scientific employment in a tightening economy
Authors: Porter Beverly Fearn , Czujko Roman
Published: October 2009

Despite the tightening economic situation, most scientists working in physics and related areas are doing relatively well. The latest statistics on members of the nine scientific societies that constitute the American Institute of Physics show overall salaries keeping pace with inflation, and the unemployment rate remaining very low at 1%. However, the slow shift away from teaching as a principal work activity appears to have accelerated. Accordingly, university employment is declining vis-à-vis industrial employment. At the same time, members of the scientific societies are continuing their westward geographical shift, particularly to the sunbelt states and away from several northern regions, most notably the north central. Although the membership of the societies is gradually aging, new members are joining, frequently from backgrounds quite different from those of their predecessors. Vacuum science, high polymer physics, chemical physics and optics are four subfields that gained a larger number of new members during the past two years.
History of medical physics
Authors: Laughlin John S.
Published: October 2009

On the occasion of the 25th anniversary of the American Association of Physicists in Medicine, it is appropriate to look at the history of the field of medical physics. This is not to imply that the history of the AAPM and the history of the field of medical physics are synonymous, but the latter does help us understand the former: By examining the history of physicists' scientific contributions to medicine, we will see how it was natural for the growing numbers of physicists involved to form a suitably oriented physical society.
The physics of medical imaging
Authors: Moran Paul R. , Nickles R. Jerome , Zagzebski James A.
Published: October 2009

The growth in the applications of physics to medicine is perhaps best illustrated by the developments in medical imaging. When AAPM was founded, medical imaging consisted primarily of x-ray fluoroscopy (direct images) and radiography (exposures on film). Although these techniques still dominate the work of a radiology department, there are a number of new ways of making images of the interior of the living body. (See, for example, the cover of this issue and figure 1.) Many of these new imaging methods depend on computers to perform the enormous amounts of data-analysis required—computed tomography or nmr imaging, for example, would not be possible without computers—and in many other cases computers serve to provide enhanced images that may allow more accurate diagnoses.
MIT tokamak Alcator C exceeds Lawson criterion
Authors: Schwarzschild Bertram M.
Published: October 2009

In 1957 John Lawson at Harwell pointed out a crucial minimum requirement for the achievement of net power output from a deuterium–tritium plasma in any fusion device. No matter what the temperature, Lawson showed, a thermalized D–T plasma cannot put out more fusion power than the input power required to keep it hot unless nτ, the product of the ion density and the energy confinement time (often refered to as the confinement parameter or Lawson parameter), exceeds 6×1013 sec cm−3.
A history of the synchrotron
Authors: McMillan Edwin M.
Published: October 2009

Speaking not as a historian but from a personal point of view, I would like to tell the story of the origin of the synchrotron as I saw it. The beginning, for me, was in the spring of 1945, when I was on the staff at Los Alamos, the wartime atomic-bomb laboratory. The Trinity test was in preparation, and I was already thinking about what to do on my return to Berkeley—from which I was on leave—after the war ended. I had spent a great deal of time and effort before the war on the design and operation of cyclotrons, I had a reasonably good understanding of the limits on the particle energies attainable by cyclotrons, and it seemed like a worthy goal to find ways to exceed these limits. The cyclotron, as you know, is a resonance accelerator; it pushes particles to high energies by the repeated application of a moderate voltage, which must be applied at the proper instant each time the particle comes around in its circular orbit.
Growing up recoil-free in India
Authors: Raghavan Ramaswamy S.
Published: October 2009

A key insight, gained almost accidentally during the investigation of a modest problem in a small area of physics, occasionally assumes a significance far beyond the original relevance and touches almost the entire discipline. Of such stuff is a great discovery sometimes made. A good example is the discovery of x rays by Wilhelm Röntgen. Another is the discovery of recoil-free gamma rays by Rudolf Mössbauer, just over 25 years ago, in 1958. Like Röntgen, Mössbauer was a Bavarian. Working at the University of Heidelberg on a mundane experiment of interest only to nuclear physicists, Mössbauer happened onto an elegant effect that enables the measurement of extremely small energy shifts of nuclear gamma rays. The discovery immediately attracted widespread interest and became a technique of great usefulness for such fields as solid-state physics, chemistry, biophysics and metallurgy, besides providing an ultrafine instrument for investigating subtle effects predicted by quantum mechanics and general relativity. That it was made while Mössbauer was still a graduate student—and earned him a Nobel prize only three years later—also made it one of the most romantic episodes in postwar physics.
The correspondence principle revisited
Authors: Liboff Richard L.
Published: October 2009

The correspondence principle addresses the connection between classical and quantum physics. The simple statement that quantum mechanics reduces to classical mechanics in the limit where the principal quantum number n approaches infinity, while found in many textbooks, is not true in general. In this article we will give special attention to the notion that the quantum frequency spectrum of a periodic system reduces to the classical spectrum in this limit. Two simple counter-examples—a particle in a cubical box, and a rigid rotator—will show us that the classical result is not always recovered in the limit of large quantum numbers.
New sources of high-power coherent radiation
Authors: Sprangle Phillip , Coffey Timothy
Published: October 2009

Recent progress in novel techniques for generating high-power coherent radiation promises to make available sources with a variety of new and exciting applications. Interestingly, the new techniques have more in common with those used in the earliest sources of coherent radiation—the various microwave generators—than with those used in the more recent optical lasers. Development of new sources based on these techniques is proceeding rapidly at research centers around the world, because the new sources have a great potential for extending the currently available range of wavelengths and levels of power, while maintaining high operating efficiencies. The areas of application that stand to benefit include spectroscopy, advanced accelerators, short-wavelength radar, and plasma heating in fusion reactors.
Infrared evidence for protoplanetary rings around seven stars
Authors: Schwarzschild Bertram M.
Published: October 2009

For the lonely among us who are eager to make contact with life elsewhere in the Universe, the abundance or scarcity of planetary systems around other stars is a particularly interesting question. Tentative reports of gravitational perturbations in the positions of a few nearby stars have been taken as very inconclusive evidence of planets, but until last summer we had no direct evidence of solid, non-stellar material orbiting any star other than our own.
Parallel architectures for computer systems
Authors: Browne James C.
Published: October 2009

People frequently do more than one thing at a time: Driving a car while listening to the radio, cooking a meal so that several dishes are ready at once, or playing two lines of melody on a piano are all familiar examples. On a larger scale, many human activities, such as building a house or complicated experimental apparatus, or putting out a magazine, are separated into what might be called “units of activity” that are performed separately by people working in parallel. On a smaller scale, our brains control separately—but in a coordinated fashion—breathing, heartbeat and several different kinds of motor activity. In each of these cases, separate units of activity are carried out by separate processors (different people or different parts of the brain, for example) that work simultaneously (at the same time, but not in lockstep) and interact to produce the final effect or product.
UA1 at CERN says it has candidates for sixth quark, top
Authors: Lubkin Gloria B.
Published: October 2009

Early in July the UA1 detector group working at the CERN proton-antiproton collider announced that they have found six candidate events suggesting the top quark. According to the standard model, quark flavors come in pairs—up and down, strange and charmed, bottom and top. The fifth quark, the bottom b, whose mass is about 5.2 GeV, was needed to explain the upsilon meson, found in 1977. But the missing sixth quark could not be found. If the mass of the top t had been less than 22 GeV, experiments at PETRA (at the DESY laboratory in Hamburg) with 22-GeV electrons colliding with 22-GeV positrons would have produced t and t̄ from the 44-GeV center-of-mass energy available.
Time-projection chambers
Authors: Madaras Ronald J. , Oddone Piermaria J.
Published: October 2009

Since its invention only ten years ago, the time-projection chamber has proven so useful as a particle detector that some are calling it the “bubble chamber” of the 1980s and 1990s. The enormous appeal of this new detector stems from its ability not only to reconstruct the trajectories of charged particles in three dimensions, but also to identify particles by measuring the ionization energy that they deposit along their tracks. The time-projection chamber can make these measurements over a large solid angle and in very crowded environments where many tracks are created at the same time.
Exploring surface structure
Authors: Tong Shuk Y.
Published: October 2009

Over the past seven or eight years, we have witnessed the development of a host of new tools for analyzing the atomic structures of surfaces. The quantitative structural information provided by these new tools has already contributed greatly to our understanding of the electronic, vibrational and chemical properties of surfaces. Through the continuing innovation of surface scientists all over the world, new and improved spectroscopies and microscopies are being invented and brought on line every year. The scanning tunneling microscope, which has an unprecedented ability to map the three-dimensional topography of surfaces, is just one recent example. (See PHYSICS TODAY, April 1982, page 21.)
Identification and characterization of the tungsten-containing class of benzoyl-coenzyme A reductases
Authors: Kung Johannes W. , Löffler Claudia , Dörner Katerina , Heintz Dimitri , Gallien Sébastien , Van Dorsselaer Alain , Friedrich Thorsten , Boll Matthias
Published: October 2009

Aromatic compounds are widely distributed in nature and can only be biomineralized by microorganisms. In anaerobic bacteria, benzoyl-CoA (BCoA) is a central intermediate of aromatic degradation, and serves as substrate for dearomatizing BCoA reductases (BCRs). In facultative anaerobes, the mechanistically difficult reduction of BCoA to cyclohexa-1,5-dienoyl-1-carboxyl-CoA (dienoyl-CoA) is driven by a stoichiometric ATP hydrolysis, catalyzed by a soluble, three [4Fe-4S] cluster-containing BCR. In this work, an in vitro assay for BCR from the obligately anaerobic
Geobacter metallireducens
was established. It followed the reverse reaction, the formation of BCoA from dienoyl-CoA in the presence of various electron acceptors. The benzoate-induced activity was highly specific for dienoyl-CoA (
K
m
= 24 ± 4 μM). The corresponding oxygen-sensitive enzyme was purified by several chromatographic steps with a 115-fold enrichment and a yield of 18%. The 185-kDa enzyme comprised 73- and 20-kDa subunits, suggesting an α
2
β
2
-composition. MS analysis revealed the subunits as products of the benzoate-induced
bamBC
genes. The αβ unit contained 0.9 W, 15 Fe, and 12.5 acid-labile sulfur. Results from EPR spectroscopy suggest the presence of one [3Fe-4S]
0/+1
and three [4Fe-4S]
+1/+2
clusters per αβ unit; oxidized BamBC exhibited an EPR signal typical for a W(V) species. The FeS clusters and the W- cofactor could only be fully reduced by dienoyl-CoA. BamBC represents the prototype of a previously undescribed class of dearomatizing BCRs that differ completely from the ATP-dependent enzymes from facultative anaerobes.
Trade-offs and synergies between carbon storage and livelihood benefits from forest commons
Authors: Chhatre Ashwini , Agrawal Arun
Published: October 2009

Forests provide multiple benefits at local to global scales. These include the global public good of carbon sequestration and local and national level contributions to livelihoods for more than half a billion users. Forest commons are a particularly important class of forests generating these multiple benefits. Institutional arrangements to govern forest commons are believed to substantially influence carbon storage and livelihood contributions, especially when they incorporate local knowledge and decentralized decision making. However, hypothesized relationships between institutional factors and multiple benefits have never been tested on data from multiple countries. By using original data on 80 forest commons in 10 countries across Asia, Africa, and Latin America, we show that larger forest size and greater rule-making autonomy at the local level are associated with high carbon storage and livelihood benefits; differences in ownership of forest commons are associated with trade-offs between livelihood benefits and carbon storage. We argue that local communities restrict their consumption of forest products when they own forest commons, thereby increasing carbon storage. In showing rule-making autonomy and ownership as distinct and important institutional influences on forest outcomes, our results are directly relevant to international climate change mitigation initiatives such as Reduced Emissions from Deforestation and Forest Degradation (REDD) and avoided deforestation. Transfer of ownership over larger forest commons patches to local communities, coupled with payments for improved carbon storage can contribute to climate change mitigation without adversely affecting local livelihoods.
Ubiquitin-dependent lysosomal targeting of GABA
A
receptors regulates neuronal inhibition
Authors: Arancibia-Cárcamo I. Lorena , Yuen Eunice Y. , Muir James , Lumb Michael J. , Michels Guido , Saliba Richard S. , Smart Trevor G. , Yan Zhen , Kittler Josef T. , Moss Stephen J.
Published: October 2009

The strength of synaptic inhibition depends partly on the number of GABA
A
receptors (GABA
A
Rs) found at synaptic sites. The trafficking of GABA
A
Rs within the endocytic pathway is a key determinant of surface GABA
A
R number and is altered in neuropathologies, such as cerebral ischemia. However, the molecular mechanisms and signaling pathways that regulate this trafficking are poorly understood. Here, we report the subunit specific lysosomal targeting of synaptic GABA
A
Rs. We demonstrate that the targeting of synaptic GABA
A
Rs into the degradation pathway is facilitated by ubiquitination of a motif within the intracellular domain of the γ2 subunit. Blockade of lysosomal activity or disruption of the trafficking of ubiquitinated cargo to lysosomes specifically increases the efficacy of synaptic inhibition without altering excitatory currents. Moreover, mutation of the ubiquitination site within the γ2 subunit retards the lysosomal targeting of GABA
A
Rs and is sufficient to block the loss of synaptic GABA
A
Rs after anoxic insult. Together, our results establish a previously unknown mechanism for influencing inhibitory transmission under normal and pathological conditions.
Distinct and overlapping roles for two Dicer-like proteins in the RNA interference pathways of the ancient eukaryote
Trypanosoma brucei
Authors: Patrick Kristin L. , Shi Huafang , Kolev Nikolay G. , Ersfeld Klaus , Tschudi Christian , Ullu Elisabetta
Published: October 2009

Trypanosoma brucei
is one of the most ancient eukaryotes where RNA interference (RNAi) is operational and is the only single-cell pathogen where RNAi has been extensively studied and used as a tool for functional analyses. Here, we report that the
T. brucei
RNAi pathway, although relying on a single Argonaute protein (AGO1), is initiated by the activities of two distinct Dicer-like enzymes. Both
Tb
DCL1, a mostly cytoplasmic protein, and the previously undescribed nuclear enzyme
Tb
DCL2 contribute to the biogenesis of siRNAs from retroposons. However,
Tb
DCL2 has a predominant role in generating siRNAs from chromosomal internal repeat transcripts that accumulate at the nucleolus in RNAi-deficient cells and in initiating the endogenous RNAi response against retroposons and repeats alike. Moreover, siRNAs generated by both
Tb
DCL1 and
Tb
DCL2 carry a 5′-monophosphate and a blocked 3′ terminus, suggesting that 3′ end modification is an ancient trait of siRNAs. We thus propose a model whereby
Tb
DCL2 fuels the
T. brucei
nuclear RNAi pathway and
Tb
DCL1 patrols the cytoplasm, posttranscriptionally silencing potentially harmful nucleic acid parasites that may access the cytoplasm. Nevertheless, we also provide evidence for cross-talk between the two Dicer-like enzymes, because
Tb
DCL2 is implicated in the generation of 35- to 65-nucleotide intermediate transcripts that appear to be substrates for
Tb
DCL1. Our finding that dcl2KO cells are more sensitive to RNAi triggers than wild-type cells has significant implications for reverse genetic analyses in this important human pathogen.
Simultaneous imaging of tumor oxygenation and microvascular permeability using Overhauser enhanced MRI
Authors: Matsumoto Shingo , Yasui Hironobu , Batra Sonny , Kinoshita Yuichi , Bernardo Marcelino , Munasinghe Jeeva P. , Utsumi Hideo , Choudhuri Rajani , Devasahayam Nallathamby , Subramanian Sankaran , Mitchell James B. , Krishna Murali C.
Published: October 2009

Architectural and functional abnormalities of blood vessels are a common feature in tumors. A consequence of increased vascular permeability and concomitant aberrant blood flow is poor delivery of oxygen and drugs, which is associated with treatment resistance. In the present study, we describe a strategy to simultaneously visualize tissue oxygen concentration and microvascular permeability by using a hyperpolarized1H-MRI, known as Overhauser enhanced MRI (OMRI), and an oxygen-sensitive contrast agent OX63. Substantial MRI signal enhancement was induced by dynamic nuclear polarization (DNP). The DNP achieved up to a 7,000% increase in MRI signal at an OX63 concentration of 1.5 mM compared with that under thermal equilibrium state. The extent of hyperpolarization is influenced mainly by the local concentration of OX63 and inversely by the tissue oxygen level. By collecting dynamic OMRI images at different hyperpolarization levels, local oxygen concentration and microvascular permeability of OX63 can be simultaneously determined. Application of this modality to murine tumors revealed that tumor regions with high vascular permeability were spatio-temporally coincident with hypoxia. Quantitative analysis of image data from individual animals showed an inverse correlation between tumor vascular leakage and median oxygen concentration. Immunohistochemical analyses of tumor tissues obtained from the same animals after OMRI experiments demonstrated that lack of integrity in tumor blood vessels was associated with increased tumor microvascular permeability. This dual imaging technique may be useful for the longitudinal assessment of changes in tumor vascular function and oxygenation in response to chemotherapy, radiotherapy, or antiangiogenic treatment.
Promoting oligodendrogenesis and myelin repair using the multiple sclerosis medication glatiramer acetate
Authors: Skihar Viktor , Silva Claudia , Chojnacki Andrew , Döring Axinia , Stallcup William B. , Weiss Samuel , Yong V. Wee
Published: October 2009

The formation of oligodendrocytes (oligodendrogenesis) and myelin is regulated by several neurotrophic factors. Strategies to increase the level of these trophic molecules may facilitate repair in demyelinating conditions, such as multiple sclerosis (MS). Because leukocytes are a source of neurotrophic factors, and as glatiramer acetate (GA) generates T helper 2 (Th2) lymphocytes that are not known to be harmful, we tested the hypothesis that GA regulates oligodendrogenesis and myelin formation. First, we generated GA-reactive Th2 cells and determined that they produced transcripts for neurotrophic factors, including insulin-like growth factor-1 (IGF-1). The conditioned medium from GA-reactive T cells elevated IGF-1 protein and promoted the formation of oligodendrocyte precursor cells (OPCs) from embryonic brainderived forebrain cells in culture. We next subjected mice to lysolecithin-induced demyelination of the spinal cord. At 7 days after the insult, the number of OPCs in the demyelinated dorsal column was higher than that in uninjured controls, and was further increased by the daily s.c. injection with GA. Increased OPC generation by GA was associated temporally with the elevation of IGF-1 and brain-derived neurotrophic factor (BDNF) in the spinal cord. Finally, the resultant remyelination at 28 days was higher in mice treated with GA during the first 7 days of injury compared with vehicle controls. These results indicate that GA promotes oligodendrogenesis and remyelination through mechanisms that involve the elevation of growth factors conducive for repair.