bluuebunny/crossref_metadata_2025 huggingface dataset:
Spring and aufeis (icing) hydrology in Brooks Range, Alaska
Authors: Yoshikawa Kenji , Hinzman Larry D. , Kane Douglas L.
Published: November 2007

Remote sensing studies and field hydrometeorological and geophysical investigations were employed to characterize several aufeis fields in the Brooks Range, Alaska. Geochemical studies were undertaken together with field hydrological measurements to better understand the chemical and thermal properties of stream base flow (groundwater spring) that contributes to winter aufeis development. The spring water temperature was measured at several major aufeis fields using data loggers throughout the year. Aufeis is an important water storage component in the Arctic and influences local ecology and geomorphology. Synthetic aperture radar (SAR) is a useful and sensitive sensor for aufeis detection and for estimating the total volume of storage as well as freeze/thaw conditions. The SAR analysis indicated that the volume of aufeis formed in winter is 27–30% of the annual groundwater discharge in the Kuparuk River. Visible and near‐IR satellite imagery indicated many of the high‐discharge springs (more than 10–1000 1/s) and aufeis fields are centered around an elevation of 600 m a.s.l. in limestone areas with glacial morphology. Geomorphological investigations indicate that many of springs have continually existed from at least the last glaciation. Microwave data (SAR), thermal infrared, short wave infrared, and visible and near‐IR bands were all used to observe the growth, decay, and distribution of aufeis deposits. The remotely sensed data indicate that the distribution of the aufeis deposits today is nearly the same as it was in past colder periods; this was mainly determined by mapping the distributed carbonate precipitates. Also, spring water temperatures and discharge volumes are predictable from the aufeis field size using remotely sensed techniques.
Ozone depletion in the 2006/2007 Arctic winter
Authors: Rösevall J. D. , Murtagh D. P. , Urban J.
Published: November 2007

Ozone depletion in the 2006/2007 Arctic winter is studied by assimilating ozone from the Odin/SMR satellite instrument into a 2‐D isentropic transport model. Cross‐isentropic transport is implemented by letting the vortex descend at a rate estimated from the inert tracer N2O. Ozone depletion is estimated by comparing ozone fields, passively transported in the model from 1 January 2007, to model fields continuously updated by assimilation of incoming satellite data. Significant ozone destruction is inferred in February and March 2007. By 15 March, an average ozone destruction in the range 0.5–1.0 ppmv is estimated north of 65° equivalent latitude at 475 K potential temperature, whilst 0.3–0.8 ppmv and 0.4–0.8 ppmv ozone destruction is estimated at 525 K and 575 K. By comparing the 2007 ozone depletion to losses inferred in 2003 and 2005 we conclude that the 2007 Arctic ozone destruction is the most severe found in the Odin/SMR data set.
Observational evidence of solar dimming: Offsetting surface warming over India
Authors: Padma Kumari B. , Londhe A. L. , Daniel S. , Jadhav D. B.
Published: November 2007

Monthly mean surface reaching solar radiation (S) measurements under all sky conditions have been evaluated for 12 stations, which are widely distributed over the Indian region, for the period 1981‐2004. It is noteworthy that all the stations showed decline in S ranging from −0.17 to −1.44 W/m2 per year. The average solar dimming observed over India for the period 1981–2004 is ∼−0.86 W/m2 per year while during winter, pre‐monsoon and monsoon seasons it is ∼−0.94, ∼−1.04 and ∼−0.74 W/m2 per year, respectively. Decadal monthly mean S for the two decades 1981–1990 and 1991–2000 showed strong decline during the second decade with an average reduction of 5% per two decades. Despite the drastic decrease in S, the all India averaged surface maximum and minimum air temperatures have been increasing. But, the change in increase in maximum temperature from the first decade to second decade is only marginal under the present situation of drastic increase in greenhouse gas emissions, while the increase in minimum temperature has been doubled.
Climate downscaling for estimating glacier mass balances in northwestern North America: Validation with a USGS benchmark glacier
Authors: Zhang Jing , Bhatt Uma S. , Tangborn Wendell V. , Lingle Craig S.
Published: November 2007

An atmosphere/glacier modeling system is described for estimating the mass balances of glaciers in both current and future climate in order to estimate their probable future contributions to rising sea level. Dynamically downscaled output from a regional atmospheric model, driven by global atmospheric reanalysis, is used to force a precipitation‐temperature‐area‐altitude (PTAA) glacier mass balance model with daily maximum and minimum temperatures and precipitation. The modeling system is verified by hindcasting the mass balances of Gulkana Glacier, a U.S. Geological Survey (USGS) benchmark glacier in the Alaska Range, U.S.A., during a ten‐year period from October 1994 to September 2004. The mass balances simulated with the atmosphere/glacier modeling system are comparable to the USGS measurements, and are also in good agreement with the meteorological station observation‐forced PTAA simulations. The results suggest this is a promising approach for realistic estimation of the future mass balances of the glaciers of northwestern North America.
Ice elevation near the West Antarctic Ice Sheet divide during the Last Glaciation
Authors: Ackert Robert P. , Mukhopadhyay Sujoy , Parizek Byron R. , Borns Harold W.
Published: November 2007

Interior ice elevations of the West Antarctic Ice Sheet (WAIS) during the last glaciation, which can serve as benchmarks for ice‐sheet models, are largely unconstrained. Here we report past ice elevation data from the Ohio Range, located near the WAIS divide and the onset region of the Mercer Ice Stream. Cosmogenic exposure ages of glacial erratics that record a WAIS highstand ∼125 m above the present surface date to ∼11.5 ka. The deglacial chronology prohibits an interior WAIS contribution to meltwater pulse 1A. Our observational data of ice elevation changes compare well with predictions of a thermomechanical ice‐sheet model that incorporates very low basal shear stress downstream of the present day grounding line. We conclude that ice streams in the Ross Sea Embayment had thin, low‐slope profiles during the last glaciation and interior WAIS ice elevations during this period were several hundred meters lower than previous reconstructions.
Ocean tidal solutions in Antarctica from GRACE inter‐satellite tracking data
Authors: Han Shin‐Chan , Ray Richard D. , Luthcke Scott B.
Published: November 2007

Long‐wavelength components of the oceanic tides surrounding Antarctica are estimated directly from three years of GRACE satellite‐to‐satellite ranging measurements. An inversion is performed for the major constituents M2, O1, and S2, with K1 excluded because of inadequate phase sampling. The tides are parameterized as localized average mass anomalies over areas approximately 3002 km2; other parameters, including satellite state adjustments, are estimated simultaneously with the tides. Qualitative comparison of our solutions with in situ tide measurements shows agreement in spatial pattern, clearly indicating regions where our adopted prior model is inadequate. To exploit these solutions, follow‐on work must assimilate these long‐wavelength components into a high‐resolution numerical tidal model.
Decadal change in east Asian summer monsoon circulation in the mid‐1990s
Authors: Kwon MinHo , Jhun Jong‐Ghap , Ha Kyung‐Ja
Published: November 2007

A climate shift in the mid‐1990s in summertime circulation over east Asia is described and the dynamics associated with the climate shift are discussed. The east Asian summer monsoon has a large interdecadal variability as well as interannual variability. It is suggested herein that the east Asian summer monsoon has undergone a decadal change in the mid‐1990s. After the mid‐1990s, there has been a significant decrease in the strength of zonal winds near the subtropical jet over the east Asia as well as a distinct increase in precipitation in the southeastern part of China. This decrease of the strength of zonal winds over east Asia could be understood as a barotropic response to a steady forcing associated with heating from increased precipitation. These decadal changes are significantly predominant only in the summertime. Concurrently, there has been a remarkable increase in the number of the typhoon passing through the southeastern part of China. It is suggested that the distinctive increase of the typhoon passing may be partly responsible for the increased precipitation in the same area after the mid‐1990s.
Solar wind control of Pc5 pulsation power at geosynchronous orbit
Authors: Takahashi Kazue , Ukhorskiy Aleksandr Y.
Published: November 2007

We statistically study the solar wind control of Pc5 magnetic pulsations at geosynchronous orbit. Solar wind conditions are quantified with the use of proton measurements at L1 from the ACE spacecraft that are propagated to the bow shock nose. In addition to the solar wind velocity, Vsw, density, Nsw, and dynamic pressure, Psw, we also consider the dynamic pressure variance in the Pc5 band, VarPsw. Pc5 pulsation parameters are derived from the GOES 8 magnetic field measurements at geosynchronous orbit at ∼10° magnetic latitude. The pulsations are quantified by three parameters: Sy, total power of the azimuthal magnetic field component in the 1.6‐ to 6.7‐mHz Pc5 band; Sz, total power of the field‐aligned (compressional) component in the same band; and Stor, the azimuthal power of narrow‐band Pc5 oscillations attributed to the fundamental toroidal standing Alfvén waves. All parameters are computed in non‐overlapping 1‐h time windows and then used in linear correlation analysis. We find that all pulsation parameters are positively correlated with Psw and VarPsw with a correlation coefficient of up to ∼0.7 on the dayside. While the correlation of pulsation parameters with the solar wind velocity and density is also positive, the correlation coefficients are smaller. We discuss three mechanisms relevant to the observed Psw and VarPsw control of pulsation power: (1) solar wind‐forcing of magnetic pulsations (breathing mode); (2) Psw control of the magnetopause‐satellite distance, which results in the Psw dependence of the amplitude of surface waves observed at the satellite; and (3) coupling of impulsively excited fast mode waves to toroidal standing Alfvén waves.
Statistical relationships between cosmic radio noise absorption and ionospheric electrical conductances in the auroral zone
Authors: Senior A. , Kavanagh A. J. , Kosch M. J. , Honary F.
Published: November 2007

Statistical models expressing the Hall and Pedersen conductances and their ratio as functions of cosmic noise absorption (CNA) are derived for five intervals of magnetic local time (MLT). The models are based on simultaneous measurements of electron densities from the European Incoherent Scatter UHF radar at Tromsø (69.6°N, 19.2°E) and absorption from the imaging riometer at Kilpisjärvi (69.1°N, 20.8°E). The Hall conductance and the conductance ratio are found to be rather strongly related to CNA, whereas the Pedersen conductance is less so. The Hall conductance‐CNA relationship is strongly dependent on MLT. These results are interpreted as being the consequence of the particular sensitivity of CNA to the typical energy of electron precipitation, the latter changing as a function of MLT as the electrons drift around the Earth. The models are compared to a previous study which did not use simultaneous measurements or take into account the MLT dependence. There is a significant difference between that study and the results presented here.
Correlation of the subauroral polarization streams (SAPS) with the Dst index during severe magnetic storms
Authors: Huang Chao‐Song , Foster John C.
Published: November 2007

The subauroral polarization stream (SAPS) is the enhanced poleward electric field/westward plasma flow in the region equatorward of the auroral electron precipitation boundary in the dusk‐midnight sector. An important characteristic of SAPS is its great intensification during magnetic storms. However, the relationship of SAPS characteristics to the strength of magnetic storms is not well known. Using Defense Meteorological Satellite Program (DMSP) satellite measurements, we have examined the location (magnetic latitude) of the SAPS channel during four severe magnetic storms with minimum Dst values between −271 and −422 nT. We find that the latitude of the SAPS channel varies directly with the magnitude of Dst. For example, in one storm case, SAPS moved from ∼60° magnetic latitude at the storm sudden commencement with Dst of near zero to ∼38° at the end of the storm main phase with Dst of −422 nT. We have identified more than 300 locations of SAPS and corresponding Dst values during the four storms. The most important finding is that the SAPS latitude is linearly correlated with Dst, and an empirical formula is derived. If the SAPS channel is mapped along the magnetic field lines to the magnetospheric equatorial plane, the mapped SAPS location corresponds to the inner edge of the ion plasma sheet and is close to the peak of the ring current. The result of this paper suggests a promising method of using ionospheric satellite and radar measurements of SAPS to monitor the evolution of the plasma sheet inner boundary and ring current during magnetic storms.
Eocene‐Oligocene paleoceanographic changes in the stratotype section, Massignano, Italy: Clues from rock magnetism and stable isotopes
Authors: Jovane Luigi , Sprovieri Mario , Florindo Fabio , Acton Gary , Coccioni Rodolfo , Dall'Antonia Barbara , Dinarès‐Turell Jaume
Published: November 2007

We have conducted high‐resolution paleomagnetic and rock magnetic studies, in addition to stable isotope analyses of the Massignano sedimentary section, which is the Global Stratotype Section and Point (GSSP) for the Eocene‐Oligocene boundary. Our research builds upon the many past studies of the Massignano section in seeking to understand the timing and nature of the paleoenvironmental variations that occurred during the transition for the Earth's climate system from greenhouse to icehouse. The new paleomagnetic results provide a refined magnetostratigraphy of the section and new age for the Eocene‐Oligocene boundary at 33.7 Ma. Abrupt and large alternations in magnetic, concentration, composition, and grain sizes that occur in the high‐resolution rock magnetic record are interpreted to be the result of rapid bimodal shifts in deep‐sea circulation that affect sediment sources or transport. We speculate that currents flowing through the gateway between the Atlantic and Indo‐Pacific Oceans may have turned on and off as the gateway was progressively closing, resulting in the deposition of two different assemblages of magnetic minerals at Massignano. Finally, stable isotope (δ18O and δ13C) data collected on ostracod valves also suggest significant changes in sea bottom circulation in the Neo‐Tethys Ocean at and about 2 m.y. before the Eocene‐Oligocene boundary.
A summer time series of particulate carbon in the air and snow at Summit, Greenland
Authors: Hagler Gayle S. W. , Bergin Michael H. , Smith Eugene A. , Dibb Jack E.
Published: November 2007

Carbonaceous particulate matter is ubiquitous in the lower atmosphere, produced by natural and anthropogenic sources and transported to distant regions, including the pristine and climate‐sensitive Greenland Ice Sheet. During the summer of 2006, ambient particulate carbonaceous compounds were characterized on the Greenland Ice Sheet, including the measurement of particulate organic (OC) and elemental (EC) carbon, particulate water‐soluble organic carbon (WSOC), particulate absorption coefficient (σap), and particle size‐resolved number concentration (PM0.1–1.0). Additionally, parallel ∼50‐day time series of water‐soluble organic carbon (WSOC), water‐insoluble organic carbon (WIOC), and elemental carbon (EC) were quantified at time increments of 4–24 h in the surface snow. Measurement of atmospheric particulate carbon found WSOC (average of 52 ng m−3) to constitute a major fraction of particulate OC (average of 56 ng m−3), suggesting that atmospheric organic compounds reaching the Greenland Ice Sheet in summer are highly oxidized. Atmospheric EC (average of 7 ng m−3) was well‐correlated with σap (r = 0.95) and the calculated mass‐absorption cross‐section (average of 24 m2 g−1) appears to be similar to that measured using identical techniques in an urban environment in the United States. Comparing surface snow to atmospheric particulate matter concentrations, it appears the snow has a much higher OC (WSOC+WIOC) to EC ratio (205:1) than air (10:1), suggesting that snow is additionally influenced by water‐soluble gas‐phase compounds. Finally, the higher‐frequency (every 4–6 h) sampling of snow‐phase WSOC revealed significant loss (40–54%) of related organic compounds in surface snow within 8 h of wet deposition.
A multiphasic characterization of the impact of the herbicide acetochlor on freshwater bacterial communities
Authors: Foley Meghan E , Sigler Von , Gruden Cyndee L
Published: November 2007

Acetochlor is the third most frequently detected herbicide in natural waters; however, it is unknown if exposure to environmentally relevant concentrations of acetochlor will impact bacterial community structure and function. This study examined the impact of acetochlor on freshwater heterotrophic bacteria number, and community structure and function using direct counting, community level physiological profiling (CLPP) and denaturing gradient gel electrophoresis (DGGE) analysis. Acetochlor concentration did not appear to correlate with the number of total (P=0.69) and viable (P=0.80) bacteria, even at concentrations up to 500 μg l−1. However, CLPP indicated that acetochlor increased functional diversity as shown by (i) an increase in the number of carbon sources utilized by the microbial community, relative to nonexposed controls and (ii) increased functional evenness within the heterotrophic bacterial community. Conversely, DGGE fingerprints suggested that exposure to acetochlor generally decreased the community complexity, as the average number of DGGE bands in most treatments was significantly less than in the control treatment. Cluster analysis of DGGE fingerprints revealed three distinct, dose-dependent clusters (i) communities exposed to 0, 1 and 5 μg l−1; (ii) 50 and 100 μg l−1 and (iii) 500 μg l−1, indicating a relationship between acetochlor concentration bacterial community changes. This study indicated that while exposure to environmentally relevant concentrations of acetochlor resulted in no significant impact to the number of freshwater bacteria, impacts to the function and structure of the community were revealed by adopting a multiphasic approach.
Excited state dynamics of metastable phthalocyanine-tetrasulfonate tetra-anions probed by pump/probe photoelectron spectroscopy
Authors: Ehrler Oli T. , Yang Ji-Ping , Sugiharto Albert B. , Unterreiner Andreas N. , Kappes Manfred M.
Published: November 2007

Femtosecond time-resolved pump-probe photoelectron spectroscopy was used to study elementary relaxation processes occurring in isolated phthalocyanine-tetrasulfonate tetra-anions ([MPc(SO3)4]4−, M=Cu,Ni, and “free-base” [H2Pc(SO3)4]4−) following Q band excitation by one-photon absorption at 775nm. Whereas the Cu and Ni systems decay rapidly by means of internal conversion without electron loss, the free-base phthalocyanine primarily undergoes excited state tunneling electron emission. This reflects less efficient coupling to lower lying states within the corresponding spin manifold. Results are interpreted in terms of (time-dependent) density functional theory calculations of ground and electronically excited states and kinetically modeled to yield the associated rates.
Conditional source-term estimation with laminar flamelet decomposition in large eddy simulation of a turbulent nonpremixed flame
Authors: Wang M. , Bushe W. K.
Published: November 2007

Conditional source-term estimation (CSE) is a method to close the mean chemical reaction source term based on the conditional moment closure hypothesis. It has been shown previously to be successful in a priori tests against direct numerical simulation data and in the large eddy simulation (LES) of a nonpremixed flame using reduced chemistry. Laminar flamelet decomposition (LFD) is a method to incorporate more complex chemistry into CSE by using laminar flamelets as basis functions and inverting an integral equation for a basis function coefficient vector which describes the linear combination of flamelets that best approximates the conditional average of certain scalar fields within an ensemble of points in a flow field. This coefficient vector is used to obtain the conditional average of the chemical source term for this ensemble of points which can then be transformed into the unconditional average chemical source term in the transport equations of reactive scalars in the flow. This study focuses on the application of CSE with LFD in LES of the Sandia D-flame. The simulation results show that LFD is able to predict temperature and major species well with both steady and unsteady flamelet libraries. However, in order to predict NO well, it is necessary to use a mixed library that includes both steady and unsteady flamelets. The computational cost of this method is low because very few transport equations need to be solved (specifically, equations for the filtered continuity, momentum, mixture fraction and its variance, temperature and the mass fraction of CO are solved) while other species mass fractions can be obtained directly from the flamelet library.
The Minkowski and conformal superspaces
Authors: Fioresi R. , Lledó M. A. , Varadarajan V. S.
Published: November 2007

We define complex Minkowski superspace in four dimensions as the big cell inside a complex flag supermanifold. The complex conformal supergroup acts naturally on this superflag, allowing us to interpret it as the conformal compactification of complex Minkowski superspace. We then consider real Minkowski superspace as a suitable real form of the complex version. Our methods are group theoretic, based on the real conformal supergroup and its Lie superalgebra.
Reduced-order modeling for unsteady transonic flows around an airfoil
Authors: Bourguet Rémi , Braza Marianna , Dervieux Alain
Published: November 2007

High-transonic unsteady flows around an airfoil at zero angle of incidence and moderate Reynolds numbers are characterized by an unsteadiness induced by the von Kármán instability and buffet phenomenon interaction. These flows are investigated by means of low-dimensional modeling approaches. Reduced-order dynamical systems based on proper orthogonal decomposition are derived from a Galerkin projection of two-dimensional compressible Navier-Stokes equations. A specific formulation concerning density and pressure is considered. Reduced-order modeling accurately predicts unsteady transonic phenomena.
Terahertz radiation from ultrahigh-speed field-effect transistors induced by ultrafast optical gate switching
Authors: Kondo T. , Hirakawa K.
Published: November 2007

We have observed terahertz radiation due to ultrafast change in drain current induced by optical gate-field modulation in high-speed field-effect transistors (FETs). This time-domain measurement is potentially applicable to the characterization of cutoff frequencies of ultrahigh-speed FETs beyond the frequency range covered by conventional swept-frequency measurements. The cutoff frequencies of sample FETs deduced by the present technique were in good agreement with those determined by a network analyzer.
Rotation driven by fast ions in tokamaks
Authors: Thyagaraja A. , Schwander F. , McClements K. G.
Published: November 2007

Collective fast ion effects on flows in tokamaks are investigated analytically and numerically. A general analysis of noncollisional electrodynamic momentum transfer from fast ions to bulk plasma is presented, with polarization effects and dissipation in the bulk plasma taken into account. The analysis is illustrated using idealized simulations of fast ion orbits and radial electric fields in the Mega-Ampère Spherical Tokamak (MAST) [A. Sykes, R. J. Akers, L. C. Appel et al., Nucl. Fusion 41, 1423 (2001)], the Joint European Torus (JET) [P. H. Rebut et al., Nucl. Fusion 25, 1011 (1985)], and ITER [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)]. In the MAST simulation, prompt losses of beam ions injected counter to the plasma current drive up a radial electric field that saturates at a level such that beam ions subsequently injected are confined electrostatically. Although the actual radial electric fields in counterinjected MAST discharges are lower than this, the scenario explored in the simulation would be approached in MAST plasmas with sufficiently low collisionality. The JET simulation, although unrealistic, shows that a similar process could be driven by losses of fusion α-particles from a burning plasma. Test-particle simulations of α-particles in ITER suggest that performance-limiting instabilities such as neoclassical tearing modes and resistive wall modes could be affected significantly by flows associated with radial fast particle currents.
High quality epitaxial CoSi2 using plasma nitridation-mediated epitaxy: The effects of the capping layer
Authors: Lee Han-Bo-Ram , Gu Gil Ho , Son J. Y. , Park C. G. , Kim Hyungjun
Published: November 2007

The epitaxial growth of CoSi2 from Co with a Ti capping layer using plasma nitridation-mediated epitaxy (PNME) was demonstrated. By exposing the Si substrate to the NH3 plasma, an a-SiNx layer was formed with atomic scale thickness controllability. After Co and Ti deposition followed by annealing, high quality epitaxial CoSi2 was formed on Si(001) with a perfectly flat interface. However, the epitaxial growth was observed for Co with a Ti capping layer prepared only by ex situ deposition, not by in situ deposition. The epitaxial CoSi2 was analyzed by x-ray diffraction and a scanning transmission electron microscope. Based on these results, the mechanism of PNME and the effects of the Ti capping layer process on silicidation were discussed.
Pentacene-based low voltage organic field-effect transistors with anodized Ta2O5 gate dielectric
Authors: Jeong Yeon Taek , Dodabalapur Ananth
Published: November 2007

Pentacene-based low voltage organic field-effect transistors were realized using an anodized Ta2O5 gate dielectric. The Ta2O5 gate dielectric layer with a surface roughness of 1.3Å was obtained by anodizing an e-beam evaporated Ta film. The device exhibited values of saturation mobility, threshold voltage, and Ion∕Ioff ratio of 0.45cm2∕Vs, 0.56V, and 7.5×101, respectively. The gate leakage current was reduced by more than 70% with a hexamethyldisilazane (HMDS) treatment on the Ta2O5 layer. The HMDS treatment also resulted in enhanced mobility values and a larger pentacene grain size.
Robert Law and His Auxiliary Assay Balance
Authors: Williams Nicola H.
Published: November 2007

In 1896, Robert Law, assayer at the Melbourne Branch of the Royal Mint, published a design for an auxiliary assay balance. This small balance was to be used for preliminary weighing of the gold sample, thus saving wear on the delicate assay balance. Versions of Law balances, including one made by the UK instrument firm of Oertling, were used in all Australian Branches of the Royal Mint, and two surviving instruments have now been found.
Arthur John Birch 1915 - 1995
Authors: Rickards Rodney W. , Cornforth Sir John
Published: November 2007

Arthur John Birch AC CMG FRS FAA was one of the great organic chemists of the twentieth century. He held chairs at the Universities of Sydney and Manchester and at the Australian National University in Canberra, and was President of the Australian Academy of Science from 1982 to 1986. His outstanding research contributions include the Birch reduction of aromatic compounds by sodium and ethanol in liquid ammonia, his polyketide theory of the biosynthesis of natural products, and his studies of synthetic applications of diene iron tricarbonyl complexes.
*This memoir is also published in Biographical Memoirs of Fellows of the Royal Society of London, 2007.
Peaking profiles for achieving long-term temperature targets with more likelihood at lower costs
Authors: den Elzen Michel G. J. , van Vuuren Detlef P.
Published: November 2007

How can dangerous interference with the climate system be avoided? Science can help decision-makers answer this political question. Earlier publications have focused on the probability of keeping global mean temperature change below certain thresholds by stabilizing greenhouse gas concentrations at particular levels. We compare the results of such “stabilization profiles” with a set of “peaking profiles” that reduce emissions further after stabilization and thus result in a concentration peak. Given the inertia in the climate system, stabilization profiles lead to ongoing warming beyond 2100 until the temperature reaches equilibrium. This warming partly can be prevented for peaking profiles. In this way, these profiles can increase the likelihood of achieving temperature thresholds by 10–20% compared with the likelihood for the associated stabilization profiles. Because the additional mitigation efforts and thus costs for peaking profiles lie mainly beyond 2100, peaking profiles achieving temperature thresholds with the same likelihood as the original stabilization profile, but at considerably lower cost (up to 40%), can be identified. The magnitude of the cost reductions depends on the assumptions on discounting. Peaking profiles and overshoot profiles with a limited overshoot may, in particular, play an important role in making more ambitious climate targets feasible.
National scientific facilities and their science impact on nonbiomedical research
Authors: Kinney A. L.
Published: November 2007

The “
h
index” proposed by Hirsch [Hirsch JE (2005)
Proc Natl Acad Sci USA
102:16569–16573] is a good indicator of the impact of a scientist's research and has the advantage of being objective. When evaluating departments, institutions, or laboratories, the importance of the
h
index can be further enhanced when it is properly calibrated for the size of the group. Particularly acute is the issue of federally funded facilities whose number of actively publishing scientists frequently dwarfs that of academic departments. Recently, Molinari and Molinari [Molinari JF, Molinari A (2008)
Scientometrics
, in press] developed a methodology that shows that the
h
index has a universal growth rate for large numbers of papers, allowing for meaningful comparisons between institutions. An additional challenge when comparing large institutions is that fields have distinct internal cultures, with different typical rates of publication and citation; biology is more highly cited than physics, for example. For this reason, the present study has focused on the physical sciences, engineering, and technology and has excluded biomedical research. Comparisons between individual disciplines are reported here to provide a framework. Generally, it was found that the universal growth rate of Molinari and Molinari holds well across the categories considered, testifying to the robustness of both their growth law and our results. The goal here is to set the highest standard of comparison for federal investment in science. Comparisons are made of the nation's preeminent private and public institutions. We find that many among the national science facilities compare favorably in research impact with the nation's leading universities.
Synchronized delta oscillations correlate with the resting-state functional MRI signal
Authors: Lu Hanbing , Zuo Yantao , Gu Hong , Waltz James A. , Zhan Wang , Scholl Clara A. , Rea William , Yang Yihong , Stein Elliot A.
Published: November 2007

Synchronized low-frequency spontaneous fluctuations of the functional MRI (fMRI) signal have recently been applied to investigate large-scale neuronal networks of the brain in the absence of specific task instructions. However, the underlying neural mechanisms of these fluctuations remain largely unknown. To this end, electrophysiological recordings and resting-state fMRI measurements were conducted in α-chloralose-anesthetized rats. Using a seed-voxel analysis strategy, region-specific, anesthetic dose-dependent fMRI resting-state functional connectivity was detected in bilateral primary somatosensory cortex (S1FL) of the resting brain. Cortical electroencephalographic signals were also recorded from bilateral S1FL; a visual cortex locus served as a control site. Results demonstrate that, unlike the evoked fMRI response that correlates with power changes in the γ bands, the resting-state fMRI signal correlates with the power coherence in low-frequency bands, particularly the δ band. These data indicate that hemodynamic fMRI signal differentially registers specific electrical oscillatory frequency band activity, suggesting that fMRI may be able to distinguish the ongoing from the evoked activity of the brain.
An influenza virus replicon system in yeast identified Tat-SF1 as a stimulatory host factor for viral RNA synthesis
Authors: Naito Tadasuke , Kiyasu Yoshihiko , Sugiyama Kenji , Kimura Ayumi , Nakano Ryosuke , Matsukage Akio , Nagata Kyosuke
Published: November 2007

Influenza viruses infect vertebrates, including mammals and birds. Influenza virus reverse-genetics systems facilitate the study of the structure and function of viral factors. In contrast, less is known about host factors involved in the replication process. Here, we developed a replication and transcription system of the negative-strand RNA genome of the influenza virus in
Saccharomyces cerevisiae
, which depends on viral RNAs, viral RNA polymerases, and nucleoprotein (NP). Disruption of
SUB2
encoding an orthologue of human RAF-2p48/UAP56, a previously identified viral RNA synthesis stimulatory host factor, resulted in reduction of the viral RNA synthesis rate. Using a genome-wide set of yeast single-gene deletion strains, we found several host factor candidates affecting viral RNA synthesis. We found that among them, Tat-SF1, a mammalian homologue of yeast CUS2, was a stimulatory host factor in influenza virus RNA synthesis. Tat-SF1 interacted with free NP, but not with NP associated with RNA, and facilitated formation of RNA-NP complexes. These results suggest that Tat-SF1 may function as a molecular chaperone for NP, as does RAF-2p48/UAP56. This system has proven useful for further studies on the mechanism of influenza virus genome replication and transcription.
Identification of acyltransferases required for cutin biosynthesis and production of cutin with suberin-like monomers
Authors: Li Yonghua , Beisson Fred , Koo Abraham J. K. , Molina Isabel , Pollard Mike , Ohlrogge John
Published: November 2007

Cutin and suberin are the two major lipid-based polymers of plants. Cutin is the structural polymer of the epidermal cuticle, the waterproof layer covering primary aerial organs and which is often the structure first encountered by phytopathogens. Suberin contributes to the control of diffusion of water and solutes across internal root tissues and in periderms. The enzymes responsible for assembly of the cutin polymer are largely unknown. We have identified two
Arabidopsis
acyltransferases essential for cutin biosynthesis, glycerol-3-phosphate acyltransferase (GPAT) 4 and GPAT8. Double knockouts
gpat4/gpat8
were strongly reduced in cutin and were less resistant to desiccation and to infection by the fungus
Alternaria brassicicola
. They also showed striking defects in stomata structure including a lack of cuticular ledges between guard cells, highlighting the importance of cutin in stomatal biology. Overexpression of GPAT4 or GPAT8 in
Arabidopsis
increased the content of C16 and C18 cutin monomers in leaves and stems by 80%. In order to modify cutin composition, the acyltransferase GPAT5 and the cytochrome P450-dependent fatty acyl oxidase CYP86A1, two enzymes associated with suberin biosynthesis, were overexpressed. When both enzymes were overexpressed together the epidermal polyesters accumulated new C20 and C22 ω-hydroxyacids and α,ω-diacids typical of suberin, and the fine structure and water-barrier function of the cuticle were altered. These results identify GPATs as partners of fatty acyl oxidases in lipid polyester synthesis and indicate that their cooverexpression provides a strategy to probe the role of cutin composition and quantity in the function of plant cuticles.
Enhanced thymic selection of FoxP3
+
regulatory T cells in the NOD mouse model of autoimmune diabetes
Authors: Feuerer Markus , Jiang Wenyu , Holler Phillip D. , Satpathy Ansuman , Campbell Christopher , Bogue Molly , Mathis Diane , Benoist Christophe
Published: November 2007

FoxP3
+
CD4
+
regulatory T cells (Tregs) play a key role in the maintenance of peripheral self-tolerance, and it has been suggested that diabetes-susceptible nonobese diabetic (NOD) mice are defective in the generation and numbers of Tregs. We found thymic selection of Tregs to be under genetic control. Fetal thymic organ cultures on the NOD background required 3- to 10-fold more antigen than corresponding cultures on the B6 background for optimal induction of Tregs, but once the threshold for induction was reached the NOD background yielded close to 10-fold more Tregs. This increased selection of Tregs was also found in nontransgenic NOD mice in fetal through adult stages. This trait did not map to the MHC,
idd3
, or the chromosome 3 (
Chr3
) regions that control clonal deletion, but mainly to two regions on
Chr1
and
Chr11
. Thus, NOD mice do not have a global defect in the generation or maintenance of Tregs; if anything, they show the opposite.
Blockade of NKG2D on NKT cells prevents hepatitis and the acute immune response to hepatitis B virus
Authors: Vilarinho Sílvia , Ogasawara Kouetsu , Nishimura Stephen , Lanier Lewis L. , Baron Jody L.
Published: November 2007

Hepatitis B virus (HBV) is a hepadnavirus that is a major cause of acute and chronic hepatitis in humans. Hepatitis B viral infection itself is noncytopathic, and it is the immune response to the viral antigens that is thought to be responsible for hepatic pathology. Previously, we developed a transgenic mouse model of primary HBV infection and demonstrated that the acute liver injury is mediated by nonclassical natural killer (NK)T cells, which are CD1d-restricted, but nonreactive to α-GalCer. We now demonstrate a role for NKG2D and its ligands in this nonclassical NKT cell-mediated immune response to hepatitis B virus and in the subsequent acute hepatitis that ensues. Surface expression of NKG2D and one of its ligands (retinoic acid early inducible-1 or RAE-1) are modulated in an HBV-dependent manner. Furthermore, blockade of an NKG2D–ligand interaction completely prevents the HBV- and CD1d-dependent, nonclassical NKT cell-mediated acute hepatitis and liver injury. This study has major implications for understanding activation of NKT cells and identifies a potential therapeutic target in treating hepatitis B viral infection.
Impacts of plant diversity on biomass production increase through time because of species complementarity
Authors: Cardinale Bradley J. , Wright Justin P. , Cadotte Marc W. , Carroll Ian T. , Hector Andy , Srivastava Diane S. , Loreau Michel , Weis Jerome J.
Published: November 2007

Accelerating rates of species extinction have prompted a growing number of researchers to manipulate the richness of various groups of organisms and examine how this aspect of diversity impacts ecological processes that control the functioning of ecosystems. We summarize the results of 44 experiments that have manipulated the richness of plants to examine how plant diversity affects the production of biomass. We show that mixtures of species produce an average of 1.7 times more biomass than species monocultures and are more productive than the average monoculture in 79% of all experiments. However, in only 12% of all experiments do diverse polycultures achieve greater biomass than their single most productive species. Previously, a positive net effect of diversity that is no greater than the most productive species has been interpreted as evidence for selection effects, which occur when diversity maximizes the chance that highly productive species will be included in and ultimately dominate the biomass of polycultures. Contrary to this, we show that although productive species do indeed contribute to diversity effects, these contributions are equaled or exceeded by species complementarity, where biomass is augmented by biological processes that involve multiple species. Importantly, both the net effect of diversity and the probability of polycultures being more productive than their most productive species increases through time, because the magnitude of complementarity increases as experiments are run longer. Our results suggest that experiments to date have, if anything, underestimated the impacts of species extinction on the productivity of ecosystems.
A specific role of AGS3 in the surface expression of plasma membrane proteins
Authors: Groves B. , Gong Q. , Xu Z. , Huntsman C. , Nguyen C. , Li D. , Ma D.
Published: November 2007

Activator of G protein signaling 3 (AGS3), originally identified in a functional screen for mammalian proteins that activate heterotrimeric G protein signaling, is known to be involved in drug-seeking behavior and is up-regulated during cocaine withdrawal in animal models. These observations indicate a potential role for AGS3 in the formation or maintenance of neural plasticity. We have found that the overexpression of AGS3 alters the surface-to-total ratios of a subset of heterologously expressed plasma membrane receptors and channels. Further analysis of the endocytic trafficking of one such protein by a biotin-based internalization assay suggests that overexpression of AGS3 moderately affects the internalization or recycling of surface proteins. Moreover, AGS3 overexpression and siRNA-mediated knockdown of AGS3 both result in the dispersal of two endogenously expressed trans-Golgi network (TGN)-associated cargo proteins without influencing those in the cis- or medial-Golgi compartments. Finally, adding a TGN-localization signal to a CD4-derived reporter renders the trafficking of fusion protein sensitive to AGS3. Taken together, our data support a model wherein AGS3 modulates the protein trafficking along the TGN/plasma membrane/endosome loop.
Molecular and Serological Characterization of Cucumber mottle virus, a New Cucurbit-Infecting Tobamo-like Virus
Authors: Orita Hiraku , Sakai Jun-ichi , Kubota Kenji , Okuda Mitsuru , Tanaka Yuko , Hanada Kaoru , Imamura Yukihisa , Nishiguchi Masamichi , Karasev Alexander V. , Miyata Shin-ichi , Iwanami Toru
Published: November 2007

A new tobamo-like virus was isolated from a greenhouse-grown cucumber that showed severe mosaic distortion on leaves and fruit, in the southern part of Japan. The virus was tentatively designated Cucumber mottle virus (CuMoV) and further characterized. The size and antigenicity of the coat protein (CP) and the complete sequence of the genome were compared with those of the known cucurbit-infecting tobamoviruses: the W and SH strains of Cucumber green mottle mosaic virus (CGMMV), the C and Y strains of Kyuri green mottle mosaic virus (KGMMV), Cucumber fruit mottle mosaic virus (CFMMV), and Zucchini green mottle mosaic virus (ZGMMV). The CP of CuMoV migrated more slowly than those of CGMMV-W and -SH and KGMMV-C and -Y in sodium dodecyl sulfate polyacrylamide gel electrophoresis. In Western blot analysis, the CP of CuMoV cross-reacted weakly with antisera against CGMMV-W and did not react with antisera against KGMMV-Y. The overall nucleotide sequence of CuMoV had 62.5 to 63.5% identity with those of CGMMV-W, -SH, KGMMV-Y, CFMMV, and ZGMMV. The genome organization was characteristic of tobamoviruses, encoding a 131-kb protein, a 188-kb protein, a movement protein (MP), and CP in 5′ to 3′ order. In the phylogenetic analyses of the CP, CuMoV was placed in a separate lineage from CGMMV-W, -SH, KGMMV-C, -Y, CFMMV, and ZGMMV. The results indicate that CuMoV is a distinct tobamovirus species which represents a third sub-subgroup in the cucurbit-infecting tobamoviruses.
Species-Specific Primers for Eutypella parasitica, the Causal Agent of Eutypella Canker of Maple
Authors: Piškur Barbara , Ogris Nikica , Jurc Dušan
Published: November 2007

Eutypella parasitica was recently reported in Europe for the first time, and this study reports the molecular evaluation of the internal transcribed spacer (ITS)1/5.8S/ITS2 regions of 68 isolates of the fungus obtained in pure culture with polymerase chain reaction restriction fragment length polymorphism (RFLP). The RFLP patterns of all isolates proved identical and the restriction profiles served to differentiate E. parasitica from Eutypa lata, another pathogenic member of the family Diatrypaceae. Low intraspecific variability was detected in the sequenced ITS1/5.8S/ITS2 regions of eight Eutypella parasitica isolates originating from different hosts and geographical locations. Based on this ITS region, EpR/F primers specific to E. parasitica were constructed and tested with a wide range of fungal isolates. The EpR/F primer pair successfully amplified the expected fragment size of 341 bp from isolates of E. parasitica and also directly from infected maple wood shavings. The RFLP patterns and species-specific primers represent a step toward routine, large-scale, and rapid molecular diagnostics and identification of E. parasitica.
Phomopsis amaranthicola and Microsphaeropsis amaranthi Symptoms on Amaranthus spp. Under South Texas Conditions
Authors: Moran Patrick J. , Showler Allan T.
Published: November 2007

Temperature, humidity, weed species and age, and inducible responses in the host are factors that could limit the efficacy of fungal bioherbicides. The influences of these factors on the efficacy of the fungal bioherbicides Phomopsis amaranthicola and Microsphaeropsis amaranthi against Palmer amaranth (Amaranthus palmeri), smooth pigweed (Amaranthus hybridus), and redroot pigweed (Amaranthus retroflexus) were investigated in greenhouse and field studies under south Texas conditions. Despite plants being given an initial dew period, the bioherbicides, applied individually or in combination, did not cause mortality on any pigweed species in greenhouse or field environments. In greenhouse experiments, fewer than 5% of the leaves in six- to eight-leaf A. palmeri plants developed necrotic lesions within 2 weeks after bioherbicide treatment and only 8% or fewer of the plants developed stem lesions. Disease incidence was significantly higher in A. hybridus and A. retroflexus, with as much as 94% of leaves developing necrosis and 95% of the plants having stem lesions. New leaf production was reduced by biobherbicide treatment in A. hybridus. Combined-pathogen inoculation caused leaf and stem lesions on mature (13 to 36 leaves per plant) A. hybridus and A. retroflexus. Summer and fall field inoculations with M. amaranthi on A. hybridus and A. palmeri produced disease incidence levels similar to or higher than those in greenhouse tests. Infection of A. palmeri by P. amaranthicola increased the peroxidase activity level nearly twofold compared with the controls. Neither pathogen influenced leaf free amino acid content. The high temperatures and low humidity of south Texas and interspecific variation in resistance, possibly linked to peroxidase induction, limited the efficacy of these bioherbicides.