bluuebunny/crossref_metadata_2025 huggingface dataset:
Abklärung der erektilen Dysfunktion beim Primärversorger
Authors: Lehmann Kurt
Published: March 2010

Die Abklärung einer erektilen Dysfunktion sollte korrigierbare Ätiologien erfassen. Empfehlenswert ist ein strukturiertes Vorgehen, da dieses semiquantitativ und reproduzierbar ist. Sie folgt im Wesentlichen einer therapieorientierten Strategie. Behandlungsziele sollten daher früh zwischen Patient und Arzt definiert werden. Solche Ziele ändern mit dem Lebensabschnitt. Gespräch und klinische Evaluation stehen heute im Vordergrund, während invasiv-technische Untersuchungen nur selten eingesetzt werden.
Diabetes mellitus Typ 2 – Seuche des modernen Lebensstils?
Authors: Henzen
Published: March 2010

Das Auftreten des Typ-2-Diabetes korreliert mit der Zunahme der Adipositas. Das Risiko an einem Typ-2-Diabetes zu erkranken, steigt schon im oberen normalen BMI-Bereich, die Mortalität ist bei einem BMI von 27 verdoppelt, bei einem BMI über 40 um das 12fache erhöht. Die genetische Prädisposition sagt nur einen kleinen Teil der Diabeteserkrankungen voraus, der Grossteil wird durch den Lebensstil verursacht, sodass bei Patienten mit einer pathologischen Glukosetoleranz punkto Prävention am meisten mit einer Veränderung des Lebensstils und der Essgewohnheiten erreicht werden kann. Der Effekt der Lebensstilsänderung ist grösser als der pharmakologische Ansatz mit Metformin oder Glitazonen. Das Ziel einer pharmakologischen Intervention beim Typ-2-Diabetes ist Lebensqualität und HbA1c unter 7%.
The Eagle and East Eagle sulfide ore‐bearing mafic‐ultramafic intrusions in the Midcontinent Rift System, upper Michigan: Geochronology and petrologic evolution
Authors: Ding Xin , Li Chusi , Ripley Edward M. , Rossell Dean , Kamo Sandra
Published: March 2010

The Eagle and East Eagle intrusions are small, subvertical dike‐like mafic‐ultramafic bodies that cut Proterozoic sedimentary strata in the Baraga Basin in northern Michigan. The Eagle intrusion hosts a newly discovered magmatic Ni‐Cu‐PGE deposit. The nearby East Eagle intrusion also contains sulfide mineralization, but the extent of this mineralization has yet to be determined by further drilling. Both intrusions contain olivine‐bearing rocks such as feldspathic peridotite, melatroctolite, and olivine melagabbro. Sulfide accumulations range from disseminated at both Eagle and East Eagle to semimassive and massive at Eagle. U‐Pb baddeleyite dating gives a crystallization age of 1107.2 ± 5.7 Ma for the Eagle intrusion, coeval with eruption of picritic basalts at the base of the volcanic succession in the Midcontinent Rift System (MRS). The Fo contents of olivine cores in the Eagle and East Eagle intrusions vary between 75 and 85 mol %, higher than those of olivine in larger layered intrusions in the MRS such as the Duluth Complex. The FeO/MgO ratios and Al2O3 contents of the parental magmas for the Eagle and East Eagle intrusions inferred from olivine and spinel compositions are similar to those of picritic basalts in the base of the MRS volcanic succession. These petrochemical data suggest that the Eagle and East Eagle intrusions are the intrusive equivalents of high‐MgO basalts that erupted in the early stages of continental magmatism associated with the development of the rift. Variations in mineral compositions and incompatible trace element ratios suggest that at least three major pulses of magmas were involved in the formation of low‐sulfide rocks in the Eagle intrusion. Lower Fo contents of olivine associated with semimassive sulfides as compared to that of olivine in low‐sulfide rocks suggest that the magma associated with the semimassive sulfide was more fractionated than the parental magmas of the low‐sulfide rocks in the Eagle intrusion. Accumulation of suspended olivine crystals and sulfide droplets from ascending magmas as they passed through wide parts of the conduits at Eagle and East Eagle played a critical role in the genesis of olivine‐rich rocks and sulfide ores in the intrusions. The Eagle Ni‐Cu‐PGE deposit typifies the conduit‐style of magmatic sulfide deposition that is associated with continental basaltic magmatism.
Geochemistry of oceanic anoxic events
Authors: Jenkyns Hugh C.
Published: March 2010

Oceanic anoxic events (OAEs) record profound changes in the climatic and paleoceanographic state of the planet and represent major disturbances in the global carbon cycle. OAEs that manifestly caused major chemical change in the Mesozoic Ocean include those of the early Toarcian (Posidonienschiefer event, T‐OAE, ∼183 Ma), early Aptian (Selli event, OAE 1a, ∼120 Ma), early Albian (Paquier event, OAE 1b, ∼111 Ma), and Cenomanian–Turonian (Bonarelli event, C/T OAE, OAE 2, ∼93 Ma). Currently available data suggest that the major forcing function behind OAEs was an abrupt rise in temperature, induced by rapid influx of CO2 into the atmosphere from volcanogenic and/or methanogenic sources. Global warming was accompanied by an accelerated hydrological cycle, increased continental weathering, enhanced nutrient discharge to oceans and lakes, intensified upwelling, and an increase in organic productivity. An increase in continental weathering is typically recorded by transient increases in the seawater values of 87Sr/86Sr and 187Os/188Os ratios acting against, in the case of the Cenomanian‐Turonian and early Aptian OAEs, a longer‐term trend to less radiogenic values. This latter trend indicates that hydrothermally and volcanically sourced nutrients may also have stimulated local increases in organic productivity. Increased flux of organic matter favored intense oxygen demand in the water column, as well as increased rates of marine and lacustrine carbon burial. Particularly in those restricted oceans and seaways where density stratification was favored by paleogeography and significant fluvial input, conditions could readily evolve from poorly oxygenated to anoxic and ultimately euxinic (i.e., sulfidic), this latter state being geochemically the most significant. The progressive evolution in redox conditions through phases of denitrification/anammox, through to sulfate reduction accompanied by water column precipitation of pyrite framboids, resulted in fractionation of many isotope systems (e.g., N, S, Fe, Mo, and U) and mobilization and incorporation of certain trace elements into carbonates (Mn), sulfides, and organic matter. Sequestration of CO2 in organic‐rich black shales and by reaction with silicate rocks exposed on continents would ultimately restore climatic equilibrium but at the expense of massive chemical change in the oceans and over time scales of tens to hundreds of thousands of years.
Noble gases in the dynamic mantle
Authors: Davies Geoffrey F.
Published: March 2010

It is proposed that noble gases in the mantle reside mainly in a “hybrid pyroxenite” component that is formed as melt from old subducted oceanic crust reacts with surrounding refractory peridotite under mid‐ocean ridges. The gases are presumed to have been acquired early in Earth history, and mixing under mid‐ocean ridges of melts from pyroxenites and old crust would pass the noble gases to successive generations of pyroxenites. Much of the complement of noble gases would not be erupted at mid‐ocean ridges and would recirculate in the mantle, so the hybrid pyroxenite would degas rather slowly over Earth history. The hybrid pyroxenite would also be denser than average mantle and would tend to settle into the D″ zone at the base of the mantle, in the same way as subducted oceanic crust. Because residence times in D″ are longer than in the rest of the mantle, the D″ pyroxenite would be less degassed and its noble gases would be less radiogenic than that in the mid‐ocean ridge basalt (MORB) source. Plumes could therefore tap a mixture of old, degassed oceanic crust and less degassed hybrid pyroxenite. This could resolve the long‐standing question of the source of unradiogenic helium in many ocean island basalts (OIBs). Abundances of noble gases are not very well constrained and are plausibly larger than conventional estimates, which would remove the need for a large, deep, “undegassed” reservoir. The 40Ar mass balance may be satisfied if account is taken of uncertainties in the potassium content of the continental crust and the bulk silicate Earth and in the Earth's total budget of 40Ar. A relatively simple quantitative theory for the evolution of the noble gases is presented that accounts for the present concentrations and isotopic compositions of helium, neon, and argon in the MORB and OIB source regions. In particular, it confirms that longer residence times in D″ can account for the less radiogenic noble gases in OIBs.
Growth of the lava dome and extrusion rates at Soufrière Hills Volcano, Montserrat, West Indies: 2005–2008
Authors: Ryan G. A. , Loughlin S. C. , James M. R. , Jones L. D. , Calder E. S. , Christopher T. , Strutt M. H. , Wadge G.
Published: March 2010

The third episode of lava dome growth at Soufrière Hills Volcano began 1 August 2005 and ended 20 April 2007. Volumes of the dome and talus produced were measured using a photo‐based method with a calibrated camera for increased accuracy. The total dense rock equivalent (DRE) volume of extruded andesite magma (306 ± 51 Mm3) was similar within error to that produced in the earlier episodes but the average extrusion rate was 5.6 ± 0.9 m3s−1 (DRE), higher than the previous episodes. Extrusion rates varied in a pulsatory manner from <0.5 m3s−1 to ∼20 m3s−1. On 18 May 2006, the lava dome had reached a volume of 85 Mm3 DRE and it was removed in its entirety during a massive dome collapse on 20 May 2006. Extrusion began again almost immediately and built a dome of 170 Mm3 DRE with a summit height 1047 m above sea level by 4 April 2007. There were few moderate‐sized dome collapses (1–10 Mm3) during this extrusive episode in contrast to the first episode of dome growth in 1995–8 when they were numerous. The first and third episodes of dome growth showed a similar pattern of low (<0.5 m3s−1) but increasing magma flux during the early stages, with steady high flux after extrusion of ∼25 Mm3.
Maximum steepness of oceanic waves: Field and laboratory experiments
Authors: Toffoli A. , Babanin A. , Onorato M. , Waseda T.
Published: March 2010

The breaking of waves is an important mechanism for a number of physical, chemical and biological processes in the ocean. Intuitively, waves break when they become too steep. Unfortunately, a general consensus on the ultimate shape of waves has not been achieved yet due to the complexity of the breaking mechanism which still remains the least understood of all processes affecting waves. To estimate the limiting shape of ocean waves, here we present a statistical analysis of a large sample of individual wave steepness. Data were collected from measurements of the surface elevation in laboratory facilities and the open sea under a variety of sea state conditions. Observations reveal that waves are able to reach steeper profiles than the Stokes' limit for stationary waves. Due to the large number of records this finding is statistically robust.
Vulcanian explosion at Soufrière Hills Volcano, Montserrat on March 2004 as revealed by strain data
Authors: Linde Alan T. , Sacks Selwyn , Hidayat D. , Voight B. , Clarke A. , Elsworth D. , Mattioli G. , Malin P. , Shalev E. , Sparks S. , Widiwijayanti C.
Published: March 2010

The CALIPSO collaborative volcano monitoring system on the Caribbean island of Montserrat includes observations of strain at depths ∼200 m using Sacks‐Evertson strainmeters. Strain data for the March 2004 explosion of the Soufrière Hills Volcano are characterized by large, roughly equal but opposite polarity changes at the two near sites and much smaller changes at a more distant site. The strain amplitudes eliminate a spherical pressure (Mogi‐type) source as the sole contributor. The initial changes are followed by smaller recoveries, but with differing relative recovery magnitudes. This dissimilarity requires a minimum of two pressure sources, which we model as a deep spherical pressure source and a shallow dike. The spherical source is fixed at the location derived from data for the massive dome collapse in July 2003. We solve for the best fitting dike plus sphere source combination. The dike geometry is consistent with earlier interpretations of dikes based on GPS data and other lines of evidence.
Seismic evidence of a ridge‐parallel strike‐slip fault off the transform system in the Gulf of California
Authors: Ortega Roberto , Quintanar Luis
Published: March 2010

A left‐lateral strike‐slip fault perpendicular to the major transform fault that occurred at the extended continental crust in the middle of the Gulf of California, produced a remarkably active main shock and aftershock seismic sequence that began on 1 September 2007. In contrast to observations from oceanic transform fault systems this event induced unusually active seismicity. By means of an inversion procedure, we obtained the moment tensor solutions of all the events greater than Mw 4.4, and we observed multiple types of faulting: some very similar to the main event, and others that included a tensional cracking mechanism with a significant nondouble couple component. Static stress change for optimally oriented left‐lateral faults predicts the seismic activity. This event has implications for the Californian peninsular geology, especially for the late Miocene fault systems that were optimally reoriented to promote active faulting.
Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories
Authors: Warneke C. , de Gouw J. A. , Del Negro L. , Brioude J. , McKeen S. , Stark H. , Kuster W. C. , Goldan P. D. , Trainer M. , Fehsenfeld F. C. , Wiedinmyer C. , Guenther A. B. , Hansel A. , Wisthaler A. , Atlas E. , Holloway J. S. , Ryerson T. B. , Peischl J. , Huey L. G. , Hanks A. T. Case
Published: March 2010

During the NOAA Southern Oxidant Study 1999 (SOS1999), Texas Air Quality Study 2000 (TexAQS2000), International Consortium for Atmospheric Research on Transport and Transformation (ICARTT2004), and Texas Air Quality Study 2006 (TexAQS2006) campaigns, airborne measurements of isoprene and monoterpenes were made in the eastern United States and in Texas, and the results are used to evaluate the biogenic emission inventories BEIS3.12, BEIS3.13, MEGAN2, and WM2001. Two methods are used for the evaluation. First, the emissions are directly estimated from the ambient isoprene and monoterpene measurements assuming a well‐mixed boundary layer and are compared with the emissions from the inventories extracted along the flight tracks. Second, BEIS3.12 is incorporated into the detailed transport model FLEXPART, which allows the isoprene and monoterpene mixing ratios to be calculated and compared to the measurements. The overall agreement for all inventories is within a factor of 2 and the two methods give consistent results. MEGAN2 is in most cases higher, and BEIS3.12 and BEIS3.13 lower than the emissions determined from the measurements. Regions with clear discrepancies are identified. For example, an isoprene hot spot to the northwest of Houston, Texas, was expected from BEIS3 but not observed in the measurements. Interannual differences in emissions of about a factor of 2 were observed in Texas between 2000 and 2006.
Diurnal variations of simulated precipitation over East Asia in two regional climate models
Authors: Koo Myung‐Seo , Hong Song‐You
Published: March 2010

The diurnal variations of precipitation over East Asia simulated by the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) and the Weather Research and Forecasting (WRF) model are evaluated during the integration period of June–July–August (JJA) 2006. The models reproduce the observed seasonal mean of large‐scale features and precipitation satisfactorily, although the bias patterns differ in both models. The lower tropospheric circulation features are better reproduced by the WRF, while the upper‐level circulations closely follow the RSM analysis. Furthermore, the RSM simulated seasonal precipitation is distinctly overestimated over land, whereas the oceanic precipitation is exaggerated by the WRF. However, the characteristics of the diurnal cycle of precipitation simulated by the two models are very similar in many aspects. Both models reproduce an afternoon peak over land and a daybreak peak over oceans. The simulated diurnal and semidiurnal cycles of precipitation amount are also comparable to the corresponding observations. However, the peaks are shifted approximately 2 h ahead. The diurnal variation of the frequency is fairly well simulated, although the semidiurnal variations are poorly resolved. The diurnal and semidiurnal variations of the intensity are not captured by either model. The ensemble mean of the model results does not provide a distinct advantage in appraising the diurnal variation of precipitation. Further physics sensitivity experiments reveal that the cumulus parameterization process influences the modulation of the simulated phase at maximum precipitation over land, whereas the amplitude is more highly controlled by the boundary layer processes.
Wind influence on snow depth distribution and accumulation over glaciers
Authors: Dadic R. , Mott R. , Lehning M. , Burlando P.
Published: March 2010

In mountain regions wind is known to cause snow redistribution. While physically based models of snow redistribution have been developed for flat to gently rolling terrain, extension of these findings to steep terrain has been limited by the complexity of wind fields in such areas. In this study, we applied a nonhydrostatic and compressible atmospheric prediction model to steep alpine topography and compared the results to a fully distributed data set of snow depth estimations. The results show reduced horizontal wind velocity as well as an increasing downward vertical wind velocity over areas with the largest winter accumulation, which are mostly glacierized. We show that the wind velocity normal to the local surface, which should be zero in a nondivergent flow field and is a direct measure of increased or decreased local deposition, is a function of small‐scale features of local topography. The correlation between wind fields, snow accumulation, and glacierization suggests that accurate modeling of wind fields over glacierized areas in complex terrain is a key factor for understanding the mass balance distribution of glaciers.
A comparison between flume and field bed load transport data and consequences for surface‐based bed load transport prediction
Authors: Recking A.
Published: March 2010

The ability of simple equations to predict bed load transport with limited knowledge of the bed surface material was investigated. This was done using a data set consisting of 7,636 bed load transport values from the flume (1,317 data) and from 84 river reaches (6,319 field data). It was possible to collapse field and flume data by correcting the ratio between the Shields number and its critical value with a very simple hiding function proposed as a power law of the D84/D50 ratio. In so doing, a surface‐based bed load transport formula was proposed. It was successfully tested on an independent data set (comprising sand and gravel bed rivers with slope in the range 0.0002–0.08), with 86% of the values predicted within a precision of 1 order of magnitude. Moreover, the formula reproduced the low transport rates well, contrary to the usual surface‐based formulas also tested, and is particularly well suited for estimating low transport rates associated with near‐bankfull flow discharge. This new formula is neither time consuming (no fractionwise calculation) nor data consuming (the required parameters are the flow discharge, the active width, the slope, and the surface grain diameters D50 and D84).
Does a property‐specific environmental health risk create a “neighborhood” housing price stigma? Arsenic in private well water
Authors: Boyle Kevin J. , Kuminoff Nicolai V. , Zhang Congwen , Devanney Michael , Bell Kathleen P.
Published: March 2010

This paper examines the impact of arsenic contamination of groundwater on sale prices of residential properties and bare land transactions in two Maine towns, Buxton and Hollis, that rely on private wells to supply their drinking water. Prompted by tests of well water by the state of Maine, media attention focused on the communities in 1993 and 1994 when 14% of private wells were found to have arsenic concentrations exceeding the U.S. Environmental Protection Agency standard of 0.05 mg/L. Households could mitigate the serious health risks associated with arsenic ingestion by purchasing bottled water or by installing a reverse osmosis home treatment system. Our results indicate that the initial arsenic finding in 1993 led to significant, but temporary, 2 year decreases in property prices. This is a much shorter effect on prices than has been observed for Superfund sites, where prices can be depressed for a decade. These results suggest that a property‐specific contamination incident that is treatable may not have a long‐lasting effect on sale prices, but further research is needed to confirm if the dissipation of the price effect was actually due to the installation of in‐home water treatment systems or due to the dissipation of perceived risk once the media coverage stopped.
Characterization of domain-selective inhibitor binding in angiotensin-converting enzyme using a novel derivative of lisinopril
Authors: Watermeyer Jean M. , Kröger Wendy L. , O'Neill Hester G. , Sewell B. Trevor , Sturrock Edward D.
Published: March 2010

Human ACE (angiotensin-converting enzyme) (EC 3.4.15.1) is an important drug target because of its role in the regulation of blood pressure via the renin–angiotensin–aldosterone system. Somatic ACE comprises two homologous domains, the differing substrate preferences of which present a new avenue for domain-selective inhibitor design. We have co-crystallized lisW-S, a C-domain-selective derivative of the drug lisinopril, with human testis ACE and determined a structure using X-ray crystallography to a resolution of 2.30 Å (1 Å=0.1 nm). In this structure, lisW-S is seen to have a similar binding mode to its parent compound lisinopril, but the P2′ tryptophan moiety takes a different conformation to that seen in other inhibitors having a tryptophan residue in this position. We have examined further the domain-specific interactions of this inhibitor by mutating C-domain-specific active-site residues to their N domain equivalents, then assessing the effect of the mutation on inhibition by lisW-S using a fluorescence-based assay. Kinetics analysis shows a 258-fold domain-selectivity that is largely due to the co-operative effect of C-domain-specific residues in the S2′ subsite. The high affinity and selectivity of this inhibitor make it a good lead candidate for cardiovascular drug development.
Retinoic acid treatment and cell aggregation independently regulate alternative splicing in P19 cells during neural differentiation
Authors: Alam AHM Khurshid , Suzuki Hitoshi , Tsukahara Toshifumi
Published: March 2010

To induce neural differentiation of P19 cells, two different treatments, RA (retinoic acid) and cell aggregation, are required. However, there has been no report that RA treatment alone or cell aggregation alone could control alternative splicing regulation in P19 cells. Therefore, we focused on alternative splicing effects by neural induction (RA treatment and/or cell aggregation) in P19 cells. We analysed the splicing patterns of several genes, including 5‐HT3R‐A (5‐hydroxytryptamine receptor), Actn1 (actinin alpha1), CUGBP2 (CUG‐binding protein) and PTB (polypyrimidine track‐binding protein), which showed different responses during the early neural induction of P19 cells. We show here that RA treatment alone changes the alternative splice mechanism of 5‐HT3R‐A. Cell aggregation alone controls alternative splicing regulation of Actn1. Both treatments (RA and cell aggregation) compensate and regulate the alternative splicing mechanism of CUGBP2. However, PTB is independent of RA and cell aggregation. Taken together, our results suggest that RA treatment and cell aggregation independently regulate the alternative splicing mechanism in the early stage of P19 cells during neural differentiation.
Core-specific adaptive regulatory T-cells in different outcomes of hepatitis C
Authors: Langhans Bettina , Braunschweiger Ingrid , Arndt Simone , Schulte Wibke , Satoguina Judith , Layland Laura E. , Vidovic Natascha , Hoerauf Achim , Oldenburg Johannes , Sauerbruch Tilman , Spengler Ulrich
Published: March 2010

CD4+ Treg-cells (regulatory T-cells) probably contribute to the impaired virus-specific T-cell responses in chronic HCV (hepatitis C virus) infection; however, their antigen-specificity has remained elusive. In the present study, we analysed peripheral blood CD4+ Treg-cells in patients with chronic hepatitis C and subjects with self-limited HCV infection and characterized individual Treg-cell clones obtained from both groups at the phenotypic and functional level. Foxp3 (forkhead box p3)+CD25+CD4+ Treg-cells were detected more frequently in patients with chronic hepatitis C than self-limited HCV infection, which responded to HCV core stimulation and inhibited proliferation of reporter cells. Cloning under limiting dilution conditions resulted in 14 and six hypoproliferative Foxp3+CD25+CD127−CD4+ T-cell clones from patients with chronic hepatitis C and subjects with self-limited HCV infection respectively. All clones expressed Treg-cell markers and produced IL (interleukin)-10 upon mitogen stimulation. However, exclusively Treg-cell clones from chronic hepatitis C produced IL-10 in response to HCV core and inhibited proliferation of reporter T-cells. These core-specific Treg-cell clones recognized epitopes in two regions of HCV core (amino acids 1–44 and 79–113). Co-culture inhibition assays demonstrated Treg-cells to inhibit reporter T-cells via secretion of IL-10 and IL-35 rather than cell-contact-dependent mechanisms. Finally, the HCV-specific Treg-cell clones lost their functional capacity, along with Foxp3 expression, if kept in culture without HCV core exposure. In conclusion, we identified functionally active HCV core-specific Treg-cells in patients with chronic hepatitis C, which share their epitopes with conventional T-cells and require the continued presence of antigen to maintain their functional differentiation. Thus HCV core-specific Treg-cells may contribute to the immunoregulatory balance in chronic hepatitis C.
Trkalian fields and Radon transformation
Authors: Saygili K.
Published: March 2010

We write the spherical curl transformation for Trkalian fields using differential forms. Then we consider Radon transform of these fields. The Radon transform of a Trkalian field satisfies a corresponding eigenvalue equation on a sphere in transform space. The field can be reconstructed using knowledge of the Radon transform on a canonical hemisphere. We consider relation of the Radon transformation with Biot–Savart integral operator and discuss its transform introducing Radon–Biot–Savart operator. The Radon transform of a Trkalian field is an eigenvector of this operator. We also present an Ampere-law type relation for these fields. We apply these to Lundquist solution. We present a Chandrasekhar–Kendall-type solution of the corresponding equation in the transform space. Lastly, we focus on the Euclidean topologically massive Abelian gauge theory. The Radon transform of an anti-self-dual field is related by antipodal map on this sphere to the transform of the self-dual field obtained by inverting space coordinates. The Lundquist solution provides an example of quantization of topological mass in this context.
Existence and Newtonian limit of nonlinear bound states in the Einstein–Dirac system
Authors: Stuart David
Published: March 2010

An analysis is given of particlelike nonlinear bound states in the Newtonian limit of the coupled Einstein–Dirac system introduced by Finster et al. [“Particle-like solutions of the Einstein-Dirac-Maxwell equations,” Phys. Lett. A 259, 431 (1999)]. A proof is given of the existence of these bound states in the almost Newtonian regime, and it is proven that they may be approximated by the energy minimizing solution of the Newton–Schrödinger system obtained by Lieb.
Investigation of rarefied supersonic flows into rectangular nanochannels using a three-dimensional direct simulation Monte Carlo method
Authors: Gatsonis Nikolaos A. , Al-Kouz Wael G. , Chamberlin Ryan E.
Published: March 2010

The rarefied flow of nitrogen with speed ratio (mean speed over most probable speed) of S=2,5,10, pressure of 10.132 kPa into rectangular nanochannels with height of 100, 500, and 1000 nm is investigated using a three-dimensional, unstructured, direct simulation Monte Carlo method. The parametric computational investigation considers rarefaction effects with Knudsen number Kn=0.481,0.962,4.81, geometric effects with nanochannel aspect ratios of (L/H) from AR=1,10,100, and back-pressure effects with imposed pressures from 0 to 200 kPa. The computational domain features a buffer region upstream of the inlet and the nanochannel walls are assumed to be diffusively reflecting at the free stream temperature of 273 K. The flow analysis is based on the phase space distributions while macroscopic flow variables sampled in cells along the centerline are used to corroborate the microscopic analysis. The phase-space distributions show the formation of a disturbance region ahead of the inlet due to slow particles backstreaming through the inlet and the formation of a density enhancement with its maximum inside the nanochannel. Velocity phase-space distributions show a low-speed particle population generated inside the nanochannel due to wall collisions which is superimposed with the free stream high-speed population. The mean velocity decreases, while the number density increases in the buffer region. The translational temperature increases in the buffer region and reaches its maximum near the inlet. For AR=10,100 nanochannels the gas reaches near equilibrium with the wall temperature. The heat transfer rate is largest near the inlet region where nonequilibrium effects are dominant. For Kn=0.481,0.962,4.81, vacuum back pressure, and AR=1, the nanoflow is supersonic throughout the nanochannel, while for AR=10,100, the nanoflow is subsonic at the inlet and becomes sonic at the outlet. For Kn=0.962, AR=1, and imposed back pressure of 120 and 200 kPa, the nanoflow becomes subsonic at the outlet. For Kn=0.962 and AR=10, the outlet pressure nearly matches the imposed back pressure with the nanoflow becoming sonic at 40 kPa and subsonic at 100 kPa. Heat transfer rates at the inlet and mass flow rates at the outlet are in good agreement with those obtained from theoretical free-molecular models. The flows in these nanochannels share qualitatively characteristics found in microflows and continuum compressible flows in channels with friction and heat loss.
Substantial increase in acceleration potential of pyroelectric crystals
Authors: Tornow W. , Lynam S. M. , Shafroth S. M.
Published: March 2010

We report on a substantial increase in the acceleration potential achieved with a LiTaO3 pyroelectric crystal. With a single 2.5 cm diameter and 2.5 cm long z-cut crystal without electric field-enhancing nanotip we produced positive ion beams with maximal energies between 300 and 310 keV during the cooling phase when the crystal was exposed to 5 mTorr of deuterium gas. These values are about a factor of 2 larger than previously obtained with single pyroelectric crystals.
Microstructural properties and dislocation evolution on a GaN grown on patterned sapphire substrate: A transmission electron microscopy study
Authors: Kim Y. H. , Ruh H. , Noh Y. K. , Kim M. D. , Oh J. E.
Published: March 2010

The microstructural properties of a GaN layer grown on a patterned sapphire substrate (PSS) were studied in detail using transmission electron microscope techniques to determine dislocation and growth behaviors. Regular and uniform recrystallized GaN islands were observed on the protruding pattern. On a flat sapphire surface, the crystallographic orientation relationship of ⟨1¯21¯0⟩GaN on FS//⟨11¯00⟩sapphire and {11¯01}GaN on FS//{12¯13}sapphire existed between the GaN and the substrate. On the other hand, the orientation relationship of ⟨1¯21¯0⟩GaN layer//⟨1¯21¯0⟩GaN island on IS//⟨11¯00⟩sapphire and {11¯01}GaN layer//{0002}GaN island on IS//{12¯13}sapphire was confirmed among the GaN layer, the recrystallized GaN islands on an inclined sapphire surface and the PSS. The flat surface among the protruding patterns began to fill rapidly with GaN. Then, the GaN gradually overgrew the protruding pattern and coalesced near the summit as the growth time increased. The generation of threading dislocations was observed in the vicinity of the coalescence points near the top of the protruding patterns.
Control of intersubband quantum well transitions with chirped electromagnetic pulses
Authors: Paspalakis Emmanuel , Simserides Constantinos , Terzis Andreas F.
Published: March 2010

We study the interaction of chirped electromagnetic pulses with intersubband transitions of a double semiconductor quantum well. We consider the ground and first excited subbands and give emphasis to controlled intersubband population transfer. The system dynamics is described by the nonlinear density matrix equations that include the effects of electron-electron interactions. These equations are solved numerically for various values of the electron sheet density for a realistic double GaAs/AlGaAs quantum well, and the efficiency of population transfer is discussed.
Stark broadening measurement of the electron density in an atmospheric pressure argon plasma jet with double-power electrodes
Authors: Qian Muyang , Ren Chunsheng , Wang Dezhen , Zhang Jialiang , Wei Guodong
Published: March 2010

Characteristics of a double-power electrode dielectric barrier discharge of an argon plasma jet generated at the atmospheric pressure are investigated in this paper. Time-averaged optical emission spectroscopy is used to measure the plasma parameters, of which the excitation electron temperature is determined by the Boltzmann's plot method whereas the gas temperature is estimated using a fiber thermometer. Furthermore, the Stark broadening of the hydrogen Balmer Hβ line is applied to measure the electron density, and the simultaneous presence of comparable Doppler, van der Waals, and instrumental broadenings is discussed. Besides, properties of the jet discharge are also studied by electrical diagnosis. It has been found that the electron densities in this argon plasma jet are on the order of 1014 cm−3, and the excitation temperature, gas temperature, and electron density increase with the applied voltage. On the other hand, these parameters are inversely proportional to the argon gas flow rate.
Absolute spectral radiance responsivity calibration of sun photometers
Authors: Xu Qiuyun , Zheng Xiaobing , Li Zhengqiang , Zhang Wei , Wang Xianhua , Li Jianjun , Li Xin
Published: March 2010

Sun photometers are designed to measure direct solar irradiance and diffused sky radiance for the purpose of atmospheric parameters characterization. A sun photometer is usually calibrated by using a lamp-illuminated integrating sphere source for its band-averaged radiance responsivity, which normally has an uncertainty of 3%–5% at present. Considering the calibration coefficients may also change with time, a regular high precision calibration is important to maintain data quality. In this paper, a tunable-laser-based facility for spectral radiance responsivity calibration has been developed at the Key Laboratory of Optical Calibration and Characterization, Chinese Academy of Sciences. A reference standard radiance radiometer, calibrated against cryogenic radiometer, is used to determine the radiance from a laser-illuminated integrating sphere source. Spectral radiance responsivity of CIMEL CE318–2 sun photometer is calibrated using this new calibration system with a combined standard uncertainty of about 0.8%. As a validation, the derived band-averaged radiance responsivity are compared to that from a Goddard Space Flight Center lamp-based sphere calibration and good agreements (difference <1.4%) are found from 675 to 1020 nm bands.
Breakdown of invariant attractors for the dissipative standard map
Authors: Calleja Renato , Celletti Alessandra
Published: March 2010

We implement different methods for the computation of the breakdown threshold of invariant attractors in the dissipative standard mapping. A first approach is based on the computation of the Sobolev norms of the function parametrizing the solution. Then we look for the approximating periodic orbits and we analyze their stability in order to compute the critical threshold at which an invariant attractor breaks down. We also determine the domain of convergence of the dissipative standard mapping by extending the computations to the complex parameter space as well as by investigating a two-frequency model.
Modeling of the reverse gate leakage in AlGaN/GaN high electron mobility transistors
Authors: Sudharsanan S. , Karmalkar Shreepad
Published: March 2010

The high gate leakage of AlGaN/GaN HEMTs grown on sapphire/SiC substrates having x=0.2, AlGaN thickness of 30 nm, and zero drain-source bias was earlier explained using the thermionic trap-assisted tunneling model. In the present work, we show that the same model can explain the gate leakage in AlGaN/GaN HEMTs grown on silicon substrates, having aluminum compositions of 24%, 26%, and 31%, AlGaN thickness of 20 nm, and drain-source bias (VDS) of 10 V, over the gate-source voltages above threshold.
Mechanically flexible polymeric compound one-dimensional photonic crystals for terahertz frequencies
Authors: Jansen Christian , Wietzke Steffen , Astley Victoria , Mittleman Daniel M. , Koch Martin
Published: March 2010

We describe the fabrication and characterization of fully flexible one-dimensional photonic crystals for terahertz frequencies based on alternating layers of a highly refracting polymeric compound and a pure polymer. Due to the high permittivity contrast and low intrinsic material absorption, even a low number of layers yields structures with a pronounced artificial band gap, with a center frequency reflectivity close to unity. Besides the high filter performance, the polymeric compound one-dimensional photonic crystals can be employed for beam shaping by applying a curvature to the mechanically flexible structures, since the spectral characteristics remain nearly unchanged when the structure is flexed.
Temperature echoes revisited to probe the vibrational behavior of dendrimers
Authors: Paulo Pedro M. R.
Published: March 2010

Temperature quench echoes were induced in molecular dynamics simulations of dendrimers. This phenomenon was used to probe the vibrational behavior of these molecules by comparing simulation results with harmonic model predictions. The echo depth for short time intervals between temperature quenches is well described by the harmonic approximation and the fluctuations observed are related to the vibrational density of states. The echo depth for long time intervals decays progressively revealing dephasing due to anharmonic interactions. The density of states was calculated from the temperature fluctuations after the first quench and high-frequency modes were assigned by comparison with vibrational spectra of similar dendrimers.
National Ignition Campaign Hohlraum energetics
Authors: Meezan N. B. , Atherton L. J. , Callahan D. A. , Dewald E. L. , Dixit S. , Dzenitis E. G. , Edwards M. J. , Haynam C. A. , Hinkel D. E. , Jones O. S. , Landen O. , London R. A. , Michel P. A. , Moody J. D. , Milovich J. L. , Schneider M. B. , Thomas C. A. , Town R. P. J. , Warrick A. L. , Weber S. V. , Widmann K. , Glenzer S. H. , Suter L. J. , MacGowan B. J. , Kline J. L. , Kyrala G. A. , Nikroo A.
Published: March 2010

The first series of experiments of the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] tested ignition Hohlraum “energetics,” a term described by four broad goals: (1) measurement of laser absorption by the Hohlraum; (2) measurement of the x-ray radiation flux (TRAD4) on the surrogate ignition capsule; (3) quantitative understanding of the laser absorption and resultant x-ray flux; and (4) determining whether initial Hohlraum performance is consistent with requirements for ignition. This paper summarizes the status of NIF Hohlraum energetics experiments. The Hohlraum targets and experimental design are described, as well as the results of the initial experiments. The data demonstrate low backscattered energy (<10%) for Hohlraums filled with helium gas. A discussion of our current understanding of NIF Hohlraum x-ray drive follows, including an overview of the computational tools, i.e., radiation-hydrodynamics codes that have been used to design the Hohlraums. The performance of the codes is compared to x-ray drive and capsule implosion data from the first NIF experiments. These results bode well for future NIF ignition Hohlraum experiments.
Thermodiffusion coefficients of binary and ternary hydrocarbon mixtures
Authors: Blanco Pablo , Bou-Ali M. Mounir , Platten J. Karl , de Mezquia David A. , Madariaga Jose A. , Santamaría Carlos
Published: March 2010

In this study, we have measured the thermodiffusion coefficients of six hydrocarbon liquid ternary mixtures at 25 °C using the thermogravitational technique. Mixtures of 1,2,3,4-tetrahydronaphthalene-isobutylbenzene-n-dodecane at four different concentrations and 1,2,3,4-tetrahydronaphthalene-isobutylbenzene-n-decane at two concentrations have been considered. We have used a plane-thermogravitational column with a small gap dimension to improve the accuracy of the recently reported data. The obtained results have been confirmed by measurements in a cylindrical column. We have also measured the thermodiffusion coefficients of 13 binary mixtures between the different components of ternaries in order to analyze the validity of the additive rule proposed in the literature to determine thermodiffusion coefficients of ternary mixtures from binary thermodiffusion data. A new correlation based on column separation, which reproduces the data within the experimental error, is proposed.
Communications: On the linear response of mechanical systems with constraints
Authors: Hartmann Carsten , Schütte Christof , Ciccotti Giovanni
Published: March 2010

We revisit the problem of the linear response of a constrained mechanical system. In doing so, we show that the standard expressions of Green and Kubo carry over to the constrained case without any alteration. The argument is based on the appropriate definition of constrained expectations by means of which Liouville’s theorem and the Green–Kubo relations naturally follow.
Metal-ceramic laminate composite magnetoelectric gradiometer
Authors: Bedekar V. , Bichurin M. I. , Ivanov S. N. , Pukinski Y. J. , Priya S.
Published: March 2010

Gradiometer resembles in functionality a magnetic field sensor where it measures the magnetic field gradient and its sensitivity is determined by the ability to quantify differential voltage change with respect to a reference value. Magnetoelectric (ME) gradiometer designed in this study is based upon the nickel (Ni)–Pb(Zr,Ti)O3 (PZT) composites and utilizes the ring-dot piezoelectric transformer structure working near the resonance as the basis. The samples had the ring-dot electrode pattern printed on the top surface of PZT, where ring acts as the input while dot acts as the output. There is an insulation gap between the input and output section of 1.2 mm. The generated magnetic field due to converse ME effect interacts with the external applied magnetic field producing flux gradient, which is detected through the frequency shift and output voltage change in gradiometer structure. The measurements of output voltage dependence on applied magnetic field clearly illustrate that the proposed design can provide high sensitivity and bandwidth.
Thermodynamic properties of short-range attractive Yukawa fluid: Simulation and theory
Authors: Orea Pedro , Tapia-Medina Carlos , Pini Davide , Reiner Albert
Published: March 2010

Coexistence properties of the hard-core attractive Yukawa potential with inverse-range parameter κ=9, 10, 12, and 15 are calculated by applying canonical Monte Carlo simulation. As previously shown for longer ranges, we show that also for the ranges considered here the coexistence curves scaled by the critical density and temperature obey the law of corresponding states, and that a linear relationship between the critical density and the reciprocal of the critical temperature holds. The simulation results are compared to the predictions of the self-consistent Ornstein–Zernike approximation, and a good agreement is found for both the critical points and the coexistence curves, although some slight discrepancies are present.
Tunable one-way cross-waveguide splitter based on gyromagnetic photonic crystal
Authors: He Cheng , Chen Xiao-Lin , Lu Ming-Hui , Li Xue-Feng , Wan Wei-Wei , Qian Xiao-Shi , Yin Ruo-Cheng , Chen Yan-Feng
Published: March 2010

We report our design of a tunable one-way cross-waveguide splitter, resulting from the broken time-reversal symmetry, based on the edge modes of gyromagnetic photonic crystal. Mode control is accomplished by altering the radius or refractive index of a single central electro-optical rod. The on-off switch of the channels can be manipulated by external electric or magnetic field. Coupled-mode theory between defect modes and waveguide modes was used to characterize the transmission efficiency of the channels.
Isotope shifts of the three lowest S1 states of the B+ ion calculated with a finite-nuclear-mass approach and with relativistic and quantum electrodynamics corrections
Authors: Bubin Sergiy , Komasa Jacek , Stanke Monika , Adamowicz Ludwik
Published: March 2010

We present very accurate quantum mechanical calculations of the three lowest S-states [1s22s2(S10), 1s22p2(S10), and 1s22s3s(S10)] of the two stable isotopes of the boron ion, B10+ and B11+. At the nonrelativistic level the calculations have been performed with the Hamiltonian that explicitly includes the finite mass of the nucleus as it was obtained by a rigorous separation of the center-of-mass motion from the laboratory frame Hamiltonian. The spatial part of the nonrelativistic wave function for each state was expanded in terms of 10 000 all-electron explicitly correlated Gaussian functions. The nonlinear parameters of the Gaussians were variationally optimized using a procedure involving the analytical energy gradient determined with respect to the nonlinear parameters. The nonrelativistic wave functions of the three states were subsequently used to calculate the leading α2 relativistic corrections (α is the fine structure constant; α=1/c, where c is the speed of light) and the α3 quantum electrodynamics (QED) correction. We also estimated the α4 QED correction by calculating its dominant component. A comparison of the experimental transition frequencies with the frequencies obtained based on the energies calculated in this work shows an excellent agreement. The discrepancy is smaller than 0.4 cm−1.