bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and realization of GaN RF-devices and circuits from 1 to 30 GHz
Authors: Kühn Jutta , Musser Markus , van Raay Friedbert , Kiefer Rudolf , Seelmann-Eggebert Matthias , Mikulla Michael , Quay Rüdiger , Rödle Thomas , Ambacher Oliver
Published: April 2010

The design, realization, and characterization of highly efficient powerbars and monolithic microwave integrated circuit (MMIC) high-power amplifiers (HPAs) with AlGaN/GaN high electronic mobility transistors (HEMTs) are presented for the frequency range between 1 and 30 GHz. Packaged powerbars for the frequency range between 1 and 6 GHz have been developed based on a process called GaN50 with a gate length of 0.5 μm. Based on a GaN25 process with a gate length of 0.25 μm, high-power MMIC amplifiers are presented starting from 6 GHz up to advanced X-band amplifiers and robust LNAs in microstrip transmission line technology.
To Group or n o t t o g r o u p
Authors: Reynolds Michael , Kwan Donna , Smilek Daniel
Published: April 2010

Eight experiments are reported that examine the contextual factors that influence the magnitude of color-word interference in the Stroop task. In Part 1 of the paper (Experiments 1–4) we varied letter-letter grouping using Gestalt principles of proximity and similarity. In Part 2 of the paper (Experiments 5–8) we varied word-color grouping using the Gestalt principles of similarity and common fate. The magnitude of the Stroop effect was strongly influenced by changes in both letter-letter grouping in the color-word and word-color grouping. Overall, the results suggest two ways in which perceptual organization influences the magnitude of Stroop color-word interference and more generally, that there are systematic principles that govern the impact of visually presented words across a variety of laboratory contexts and the real world.
What You Fear Will Appear
Authors: Peira Nathalie , Golkar Armita , Larsson Maria , Wiens Stefan
Published: April 2010

Various experimental tasks suggest that fear guides attention. However, because these tasks often lack ecological validity, it is unclear to what extent results from these tasks can be generalized to real-life situations. In change detection tasks, a brief interruption of the visual input (i.e., a blank interval or a scene cut) often results in undetected changes in the scene. This setup resembles real-life viewing behavior and is used here to increase ecological validity of the attentional task without compromising control over the stimuli presented. Spider-fearful and nonfearful women detected schematic spiders and flowers that were added to one of two identical background pictures that alternated with a brief blank in between them (i.e., flicker paradigm). Results showed that spider-fearful women detected spiders (but not flowers) faster than did nonfearful women. Because spiders and flowers had similar low-level features, these findings suggest that fear guides attention on the basis of object features rather than simple low-level features.
A completeness analysis of the National Seismic Network of Italy
Authors: Schorlemmer D. , Mele F. , Marzocchi W.
Published: April 2010

We present the first detailed study of earthquake detection capabilities of the Italian National Seismic Network and of the completeness threshold of its earthquake catalog. The network in its present form started operating on 16 April 2005 and is a significant improvement over the previous networks. For our analysis, we employed the PMC method as introduced by Schorlemmer and Woessner (2008). This method does not estimate completeness from earthquake samples as traditional methods, mostly based on the linearity of earthquake size distributions. It derives detection capabilities for each station of the network and synthesizes them into maps of detection probabilities for earthquakes of a given magnitude. Thus, this method avoids the many assumptions about earthquake distributions that traditional methods make. The results show that the Italian National Seismic Network is complete at M = 2.9 for the entire territory excluding the islands of Sardinia, Pantelleria, and Lampedusa. At the M = 2.5 level, which is the reporting threshold level of the Italian Civil Protection, the network may miss events in southern parts of Apulia and the western part of Sicily. The stations are connected through many different telemetry links to the operational data center in Rome. Scenario computations show that no significant drop in completeness occurs if one of the three major links fails, indicating a well‐balanced network setup.
Dynamic simulation of the 1999 Chi‐Chi, Taiwan, earthquake
Authors: Zhang Wenbo , Iwata Tomotaka , Irikura Kojiro
Published: April 2010

We apply a modified three‐dimensional finite difference method to investigate the dynamics of the 1999 Chi‐Chi earthquake. We determine the dynamic source rupture process and simulate the strong ground motions over a frequency range of 0.05–0.5 Hz. Our dynamic source model reveals that the rupture process of the Chi‐Chi earthquake is much more complex than that described in the classical propagation rupture models. The Chi‐Chi earthquake rupture process includes the jumping phenomenon. The northern parts on the fault plane have a longer slip duration than the southern parts. The motions on the hanging wall are larger than those on the footwall side, which is a consequence of the asymmetry of the fault with respect to the free surface. In general, the synthetics calculated by the dynamic source model agree well with the observed data. Our dynamic source model reproduces distinctive velocity pulses at stations located in the forward rupture direction and at stations close to the fault surface breaks. The apparent rupture directivity, propagating from south to north, then produces noticeably larger peak ground velocity to the north. These results demonstrate that the dynamic rupture model reproduces the main features of long‐period ground motions. These results may lead to improved understanding of rupture processes accompanying large earthquakes. The dynamic modeling scheme may produce more reasonable and reliable strong ground motion predictions for assessment of seismic hazard.
Inelastic off‐fault response and three‐dimensional dynamics of earthquake rupture on a strike‐slip fault
Authors: Ma Shuo , Andrews D. J.
Published: April 2010

Large dynamic stress off the fault incurs an inelastic response and energy loss, which contributes to the fracture energy, limiting the rupture and slip velocity. Using an explicit finite element method, we model three‐dimensional dynamic ruptures on a vertical strike‐slip fault in a homogeneous half‐space. The material is subjected to a pressure‐dependent Drucker‐Prager yield criterion. Initial stresses in the medium increase linearly with depth. Our simulations show that the inelastic response is confined narrowly to the fault at depth. There the inelastic strain is induced by large dynamic stresses associated with the rupture front that overcome the effect of the high confining pressure. The inelastic zone increases in size as it nears the surface. For material with low cohesion (∼5 MPa) the inelastic zone broadens dramatically near the surface, forming a “flowerlike” structure. The near‐surface inelastic strain occurs in both the extensional and the compressional regimes of the fault, induced by seismic waves ahead of the rupture front under a low confining pressure. When cohesion is large (∼10 MPa), the inelastic strain is significantly reduced near the surface and confined mostly to depth. Cohesion, however, affects the inelastic zone at depth less significantly. The induced shear microcracks show diverse orientations near the surface, owing to the low confining pressure, but exhibit mostly horizontal slip at depth. The inferred rupture‐induced anisotropy at depth has the fast wave direction along the direction of the maximum compressive stress.
Upper mantle deformation beneath the North American–Pacific plate boundary in California from SKS splitting
Authors: Bonnin Mickael , Barruol Guilhem , Bokelmann Götz H. R.
Published: April 2010

In order to constrain the vertical and lateral extent of deformation and the interactions between lithosphere and asthenosphere in a context of a transpressional plate boundary, we performed teleseismic shear wave splitting measurements for 65 permanent and temporary broadband stations in central California. We present evidence for the presence of two anisotropic domains: (1) one with clear E–W trending fast directions and delay times in the range 1.5 to 2.0 s and (2) the other closely associated with the San Andreas Fault system with large azimuthal variations of the splitting parameters that can be modeled by two anisotropic layers. The upper of the two layers provides fast directions close to the strike of the main Californian faults and averaged delay times of 0.7 s; the lower layers show E–W directions and delay times in the range 1.5 to 2.5 s and thus can be compared to what is observed in stations that require a single layer. We propose the E–W trending anisotropic layer to be a 150 to 200 km thick asthenospheric layer explained by the shearing associated with the absolute plate motion of the North American lithosphere. The shallower anisotropic layer ought to be related to the dynamics of the San Andreas Fault system and thus characterized by a vertical foliation with lineation parallel to the strike of the faults localized in the lithosphere. We also propose that the anisotropic layer associated with each fault of the San Andreas Fault system is about 40 km wide at the base of the lithosphere.
Observations of increased wind‐driven coastal upwelling off central California
Authors: García‐Reyes M. , Largier J.
Published: April 2010

Alongshore wind speed and sea surface temperature (SST) from coastal National Data Buoy Center buoys are used to study the variability of wind‐driven coastal upwelling from 1982 to 2008. A long‐term increase in upwelling is observed in central California (35°N–39°N) with stronger upwelling‐favorable winds, colder water, and more frequent occurrences of upwelling days during the upwelling season (March–July). Further, a longer upwelling season is observed in the same region, starting earlier in the spring and persisting later in the fall. These interannual changes in upwelling strength and seasonal duration are investigated in this study. Changes in alongshore wind (forcing of upwelling) are poorly correlated with the El Niño–Southern Oscillation or the Pacific Decadal Oscillation, but the Northern Oscillation and the North Pacific Gyre Oscillation correlate with the geostrophic upwelling‐favorable winds in the region. However, changes in SST (an upwelling response) are correlated with both changes in wind (upwelling forcing) and the climate indices. Although this short record cannot differentiate between multidecadal cycles and persistent trends, this data‐based result does corroborate model‐based projections of increased upwelling in this region due to global climate change. This increase in upwelling is understood to be a response to the strengthening of large‐scale pressure gradient fields partially due to global‐scale climate change. Farther north and farther south in California, other processes also have a significant influence on coastal conditions, such that the tendency for increased upwelling is not evident in the same way.
Extreme wave climate variability in southern Europe using satellite data
Authors: Izaguirre Cristina , Mendez Fernando J. , Menendez Melisa , Luceño Alberto , Losada Inigo J.
Published: April 2010

A time‐dependent generalized extreme value (GEV) model for monthly significant wave height maxima from satellite databases is used to model the seasonal and interannual variability of the extreme wave climate throughout southern Europe. In order to avoid a misleading use of the maxima time series, the classical extreme value model has been modified to cope with nonhomogeneous monthly observations. Seasonality is represented using intraannual harmonic functions in the model, while interannual variability is modeled including North Atlantic and Mediterranean regional scale sea level pressure predictors, such as the North Atlantic Oscillation (NAO), the east Atlantic (EA), or the east Atlantic/western Russian (EA/WR) patterns. The results quantify the strong spatial variability detected in the seasonal location and scale GEV parameters. In general, prominent zonal (west–east) and meridional (north–south) gradients of these location and scale parameters reveal the predominance of low‐pressure centers located in the NAO region (e.g., a gradient of 4 m for the location parameter and 1.5 units for the scale parameter between north–south is shown in the month of September). The model also quantifies the influence of regional climate patterns on extreme wave climate. Results show a great influence of NAO and EA on the Atlantic basin (e.g., every unit of the monthly NAO index explains 25 cm of the extreme wave height in the Gulf of Biscay and the EA index explains 20 cm) while the negative phases of EA/WR contribute greatly to the western Mediterranean basin.
Microphysical properties of Antarctic polar stratospheric clouds and their dependence on tropospheric cloud systems
Authors: Adhikari Loknath , Wang Zhien , Liu Dong
Published: April 2010

Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellite measurements are used to investigate the impact of tropospheric high and deep clouds on the microphysical properties of polar stratospheric clouds (PSCs) over Antarctica during the 2006 and 2007 winters. Based on the attenuated lidar scattering ratio and PSC depolarization ratio (δ′), PSCs are classified into supercooled ternary solution (STS), Mix 1, Mix 2, and ice classes with significantly different microphysical properties in terms of the PSC backscattering coefficient (β532) for 532 nm, the color ratio (β1064/β532), and δ′. In the early stages of the PSC season, STS accounts for more than 50% of the total PSCs, but the Mix 1, Mix 2, and ice classes become more common in the late season. During the late PSC season, close to 70% of PSCs are formed in association with high and deep tropospheric cloud systems, indicating the important role of tropospheric weather systems in Antarctic PSC formation. Tropospheric cloud systems also affect the microphysical properties of PSCs by affecting the relative occurrence of different PSC classes, especially during September and October. Our results also show that there are noticeable differences in color ratio and β532 (at the 0.05 significance level) for the ice class and Mix 2 (late season only) for PSCs associated and not associated with high and deep tropospheric cloud systems. These results indicate that the impact of tropospheric meteorology on PSC formation should be fully considered to better understand interannual variations and recovery of the Antarctic ozone hole.
Microphysical parameters of mesospheric ice clouds derived from calibrated observations of polar mesosphere summer echoes at Bragg wavelengths of 2.8 m and 30 cm
Authors: Li Qiang , Rapp Markus , Röttger Jürgen , Latteck Ralph , Zecha Marius , Strelnikova Irina , Baumgarten Gerd , Hervig Mark , Hall Chris , Tsutsumi Masaki
Published: April 2010

The currently most widely accepted theory of polar mesosphere summer echoes (PMSE) assumes that the echoes originate from turbulence‐induced scatter in combination with a large Schmidt number caused by the presence of charged ice particles. We test this theory with calibrated observations with the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR) at 500 MHz (Bragg wavelength 30 cm) and the Sounding System (SOUSY) Svalbard Radar (SSR) at 53.5 MHz (Bragg wavelength 2.8 m), which are collocated near Longyearbyen on Svalbard (78°N, 16°E). Our observations in June 2006 yield volume reflectivities ranging from values of 2.5 × 10−19 m−1 to 1 × 10−17 m−1 for the case of the ESR echoes and from 5 × 10−16 m−1 to 6.3 × 10−12 m−1 for the SSR echoes. In the frame of the above‐mentioned theory the expected reflectivity ratio should be equal to or larger than the ratio of the frequencies to the third power (i.e., larger than (500 MHz/53.5 MHz)3 = 816). Our experimental results show that 94% of the observations satisfy this expectation. The remaining 6%, which show too small ratios, can be tentatively attributed to calibration uncertainties and an incomplete filling of the scattering volume of the SSR, which is significantly larger than that of the ESR. Hence our observations are largely consistent with the predictions of the above‐mentioned theory even though we note that it cannot prove it, which would require additional observations at different frequencies. However, this consistency is used as sufficient motivation to apply the assumed theory to the observations in order to derive Schmidt numbers and radii of the charged aerosol particles. Corresponding results are in excellent agreement with expectations from microphysical models and independent satellite and lidar observations, thereby corroborating our initial assumptions.
Spatiotemporal changes in sunshine duration and cloud amount as well as their relationship in China during 1954–2005
Authors: Xia Xiangao
Published: April 2010

Long‐term trends in cloud amount and sunshine duration have been studied based upon surface observations at 618 meteorological stations across China. The degree of agreement between the two measures at interannual and decadal scales is analyzed, and a further understanding of the trends in sunshine duration is presented. A significant decreasing trend has been derived for sunshine duration (SSD) and total cloud cover (TCC); however, low‐level cloud cover (LCC) shows an increasing trend, although it is not significant at the 95% level. Interannual variability of SSD is strongly inversely correlated to that of TCC and LCC, indicating short‐term variability of SSD is dominantly determined by cloudiness. A positive correlation between decadal changes in SSD and TCC suggests long‐term change in TCC cannot account for the decreasing trend in SSD. Long‐term change in LCC appears to be one of important contributors to the trend in SSD in southern China, where long‐term changes in SSD are inversely correlated to those of LCC. The decreasing trend in SSD is contributed by the declines in average SSDs under clear sky (13%), cloudy (51%), and overcast conditions (36%), 30% of which is offset by an increase in the frequency of clear sky.
Silica in a Mars analog environment: Ka'u Desert, Kilauea Volcano, Hawaii
Authors: Seelos Kimberly D. , Arvidson Raymond E. , Jolliff Bradley L. , Chemtob Steven M. , Morris Richard V. , Ming Douglas W. , Swayze Gregg A.
Published: April 2010

Airborne Visible/Near‐Infrared Imaging Spectrometer (AVIRIS) data acquired over the Ka'u Desert are atmospherically corrected to ground reflectance and used to identify the mineralogic components of relatively young basaltic materials, including 250–700 and 200–400 year old lava flows, 1971 and 1974 flows, ash deposits, and solfatara incrustations. To provide context, a geologic surface units map is constructed, verified with field observations, and supported by laboratory analyses. AVIRIS spectral end‐members are identified in the visible (0.4 to 1.2 μm) and short wave infrared (2.0 to 2.5 μm) wavelength ranges. Nearly all the spectral variability is controlled by the presence of ferrous and ferric iron in such minerals as pyroxene, olivine, hematite, goethite, and poorly crystalline iron oxides or glass. A broad, nearly ubiquitous absorption feature centered at 2.25 μm is attributed to opaline (amorphous, hydrated) silica and is found to correlate spatially with mapped geologic surface units. Laboratory analyses show the silica to be consistently present as a deposited phase, including incrustations downwind from solfatara vents, cementing agent for ash duricrusts, and thin coatings on the youngest lava flow surfaces. A second, Ti‐rich upper coating on young flows also influences spectral behavior. This study demonstrates that secondary silica is mobile in the Ka'u Desert on a variety of time scales and spatial domains. The investigation from remote, field, and laboratory perspectives also mimics exploration of Mars using orbital and landed missions, with important implications for spectral characterization of coated basalts and formation of opaline silica in arid, acidic alteration environments.
Global Cerebral Oxidative Metabolism during Hypercapnia and Hypocapnia in Humans: Implications for BOLD fMRI
Authors: Chen J Jean , Pike G Bruce
Published: April 2010

The effect of carbon dioxide (CO2) on cerebral metabolism is of tremendous interest to functional imaging. In particular, mild-to-moderate hypercapnia is routinely used in calibrated blood oxygen-level dependent (BOLD)-functional magnetic resonance imaging (fMRI)-based quantification of cerebral oxidative metabolism changes (ΔCMRO2), and relies on the assumption of a stable CMRO2 during CO2 challenges. However, this assumption has been challenged by certain animal studies, necessitating its verification in humans and under conditions customary to fMRI. We report, for the first time, on global ΔCMRO2 measurements made noninvasively in humans during graded hypercapnia and hypocapnia. We used computerized end-tidal CO2 modulation to minimize undesired concurrent changes in oxygen pressure, and our findings suggest that no significant change in global CMRO2 is expected at the levels of end-tidal CO2 changes customary to calibrated BOLD.
Cerebellum as the Normal Reference for the Detection of Increased Cerebral Oxygen Extraction
Authors: Jiang Thomas T , Videen Tom O , Grubb Robert L , Powers William J , Derdeyn Colin P
Published: April 2010

Hemispheric ratios of oxygen extraction fraction (OEF), a proven methodology for the detection of severe hemodynamic impairment and stroke risk, are not sensitive for detecting bilateral hemispheric increases in OEF. The aim of this study was to investigate the use of cerebellum as the reference normal. We analyzed positron emission tomographic (PET) measurements of count-based OEF and clinical data from 57 patients with unilateral atherosclerotic carotid occlusion and 13 controls enrolled in a prospective study of stroke risk. The ipsilateral, contralateral, and total cerebellum were each evaluated as possible reference regions, and the ratios of the middle cerebral artery (MCA) hemispheric OEF counts against those in each reference region were determined. A statistically significant correlation ( P<0.0001) was observed with all three MCA-to-cerebellar ratios when compared with the gold standard of ipsilateral-to-contralateral MCA hemispheric ratio. Kaplan–Meier analyses showed all MCA-to-cerebellar ratios to be predictive of stroke. By using the total cerebellum method, 7 strokes were found to have occurred in 20 patients with increased OEF ( P=0.0007), compared with 7 strokes out of 16 patients with elevated OEF using the ipsilateral or contralateral cerebellum methods ( P<0.0001). These methods may be useful for categorizing the hemodynamic status of patients with bilateral cerebral occlusive diseases, including atherosclerosis and moyamoya, to determine the association with the risk of subsequent stroke.
Changes in the Vascular Area Fraction of the Hippocampus and Amygdala are Induced by Prenatal Dexamethasone and/or Adult Stress
Authors: Neigh Gretchen N , Owens Michael J , Taylor W Robert , Nemeroff Charles B
Published: April 2010

In addition to the neuronal and behavioral consequences of excess glucocorticoid exposure, the cerebrovascular system can also be adversely affected by stressors. This study determined that chronic stress in adulthood decreased the vascular area fraction of the hippocampus and increased the vascular area fraction of the amygdala. In addition, the data indicated that prenatal exposure to synthetic glucocorticoids modulated the effects of adult stress on vascular area fraction of the hippocampus and amygdala. These data indicate that in addition to the well-documented stress-induced changes in neurons and glia, cerebral vasculature is also altered by exposure to stressors.
Direct modifications of Rho proteins: deconstructing GTPase regulation
Authors: Visvikis Orane , Maddugoda Madhavi P. , Lemichez Emmanuel
Published: April 2010

Small GTPases of the Rho protein family are master regulators of the actin cytoskeleton and are targeted by potent virulence factors of several pathogenic bacteria. Their dysfunctional regulation can lead to severe human pathologies. Both host and bacterial factors can activate or inactivate Rho proteins by direct post‐translational modifications: such as deamidation and transglutamination for activation, or ADP‐ribosylation, glucosylation, adenylylation and phosphorylation for inactivation. We review and compare these unconventional ways in which both host cells and bacterial pathogens regulate Rho proteins.
Family Quality of Life Following Early Identification of Deafness
Authors: Jackson Carla W. , Wegner Jane R. , Turnbull Ann P.
Published: April 2010

Purpose

Family members' perceptions of their quality of life were examined following early identification of deafness in children.

Method

A questionnaire was used to solicit ratings of satisfaction from the family members of 207 children who were deaf and younger than 6 years of age.

Results

Results indicated that families were generally satisfied with the areas of family life surveyed. Descriptive analysis suggested lower satisfaction ratings in the area of emotional well-being. Families also reported that their child’s deafness had the largest impact on their emotional well-being. Family members of children using oral communication with a cochlear implant reported higher satisfaction with their child’s speech production and perception outcomes than family members of children using hearing aids alone.

Implications

We recommend that service providers and early hearing detection and intervention program coordinators consider additional supports for family well-being following the early identification of deafness in children.
Augmented Ehrenfest dynamics yields a rate for surface hopping
Authors: Subotnik Joseph E.
Published: April 2010

We present a new algorithm for mixed quantum-classical dynamics that helps bridge the gap between mean-field (Ehrenfest) and surface-hopping dynamics by defining a natural rate of decoherence. In order to derive this decoherence result, we have expanded the number of independent variables in the usual Ehrenfest routine so that mixed quantum-classical derivatives are now propagated in time alongside the usual Ehrenfest variables. Having done so, we compute a unique rate of decoherence using two independent approaches: (i) by comparing the equations of motion for the joint nuclear-electronic probability density in phase space according to Ehrenfest dynamics versus partial Wigner transform dynamics and (ii) by introducing a frozen Gaussian interpretation of Ehrenfest dynamics which allows nuclear wave packets to separate. The first consequence of this work is a means to rigorously check the accuracy of standard Ehrenfest dynamics. Second, this paper suggests a nonadiabatic dynamics algorithm, whereby the nuclei are propagated on the mean-field (Ehrenfest) potential energy surface and undergo stochastic decoherence events. Our work resembles the surface-hopping algorithm of Schwartz and co-workers [J. Chem. Phys. 123, 234106 (2005)]—only now without any adjustable parameters. For the case of two electronic states, we present numerical results on the so-called “Tully problems” and emphasize that future numerical benchmarking is still needed. Future work will also treat the problem of three or more electronic states.
Charge and spin currents in a ballistic SNS Josephson junction between p-wave superconductors
Authors: Rashedi G. , Rahnavard Y. , Kolesnichenko Yu. A.
Published: April 2010

The charge and spin transport properties of a clean TS–N–TS Josephson junction (triplet superconductor-normal metal-triplet superconductor) are studied using the quasiclassical Eilenberger equation for the Green’s function. The effects of the thickness of normal layer between superconductors on the spin and charge currents are investigated. The effect of misorientation between the triplet superconductors which creates the spin current is the main subject of this paper. It is shown that for some values of the phase difference between the superconductors a spin current exists in the absence of charge current and vice versa.
Low-temperature phase transitions in the rare-earth ferroborate Nd0.75Dy0.25Fe3(BO3)4
Authors: Zvyagina G. A. , Zhekov K. R. , Bilych I. V. , Zvyagin A. A. , Bezmaternyhk L. N. , Gudim I. A.
Published: April 2010

The low-temperature behavior of the elastic characteristics of a Nd0.75Dy0.25Fe3(BO3)4 single crystal has been studied. Features are found in the temperature and magnetic-field dependences of the velocity and absorption of transverse sound. These features are interpreted as being a manifestation of magnetic phase transitions in the compound studied. The H-T phase diagram is constructed.
Preparation and characterization of barium hexagonal ferrite thin films on a Pt template
Authors: Nie Yan , Harward I. , Balin K. , Beaubien A. , Celinski Z.
Published: April 2010

M-type barium hexagonal ferrite films with the crystallographic c axis out of plane were successfully deposited onto a Pt template using a metallo-organic decomposition technique. For the best film, x-ray diffraction patterns revealed strong (00l) reflections and a texture fraction of 0.953, confirming the out of plane c axis orientation. Atomic force microscopy images confirm hexagonal grains in this film with an average lateral size of ∼500 nm. Hysteresis loops revealed a high effective out of plane anisotropy field, high perpendicular remanent magnetization Mr=0.93 Ms, and out of plane coercivity of 4.5 kOe. Out of plane Ferromagnetic Resonance measurements determined the values of γ=2.79 GHz/kOe and effective anisotropy field. The full width at half maximum FMR linewidth was 338 Oe at 60 GHz. These properties are suitable for possible use in on-wafer millimeter wave devices.
Dopant-vacancy cluster formation in germanium
Authors: Chroneos A.
Published: April 2010

Recent experimental and theoretical studies revealed that dopants in germanium (Ge) cluster with lattice vacancies (V). The existence of these larger clusters has been recently predicted and is important as they can contribute to the low activation of dopants in Ge. With the use of electronic structure calculations we study the binding energies of clusters formed with the association of dopant atoms and vacancies. As an example of the kinetics of such clusters the diffusion of two phosporous-vacancy (P2 V) clusters via the ring mechanism of diffusion in predicted. These P2 V clusters are important as they can act as precursors for the formation of the larger P3 V and P4 V clusters. The present study provides information on the structure of clusters and is consistent with recent experimental results, which indicate that the formation of clusters in heavily doped Ge is possible. In agreement with experiment, we predict that the diffusion of P V pairs is retarded by the addition of a further P atom.
Permeability of a bubble assembly: From the very dry to the wet limit
Authors: Rouyer Florence , Pitois Olivier , Lorenceau Elise , Louvet Nicolas
Published: April 2010

Bubble assemblies offer the remarkable property of adjusting their packing fraction over three orders of magnitude, thus providing an interesting system for the study of liquid flows through granular matter. Although significant work has been done in several fields of research, e.g., foams, porous media, and suspensions, a complete set of data over such a wide range of porosity ε is still lacking. In this paper, we measure the permeability of a bubbly system in the range 0.1<ε<0.8 and we connect these new data with a recently published set obtained for foams corresponding to ε<0.2 [E. Lorenceau et al., Eur. Phys. J. E 28, 293 (2009)]. Moreover, measurements performed with two different surfactants, the so-called “mobile” and “nonmobile” interfaces, allow us to determine the influence of the bubbles’ surface mobility, which is proved to be a significant parameter up to ε≈0.6, thus well above the bubbles packing fraction. Above ε≈0.6, surface elasticity is fully mobilized over the bubbles’ surface and the behavior of rigid spheres is observed for both solutions. We show that all the permeability values obtained for the bubble assembly with “nonmobile” interfaces are properly described with the Carman–Kozeny model.
Tuning of the Schottky barrier height in NiGe/n-Ge using ion-implantation after germanidation technique
Authors: Guo Yue , An Xia , Huang Ru , Fan Chunhui , Zhang Xing
Published: April 2010

In this paper, a method of ion-implantation after germanidation (IAG) has been presented to modulate the Schottky barrier (SB) heights on germanium substrates. Schottky diodes have been fabricated with improved rectifying current curves and larger Ion/Ioff ratio up to 106. A relatively high effective electron barrier height for NiGe/n-Ge has been achieved by the BF2+ IAG technique, which suggests a record-low effective hole barrier height of nearly 0.06 eV. The tuning of SB height can be mainly contributed to the effects of fluorine. In addition, there is a process temperature window between 350 to 450 °C for the drive-in annealing of IAG to obtain optimized SB heights. These results provide the design guidelines for the process integration of germanium based Schottky barrier source/drain metal-oxide-semiconductor field-effect transistors.
Design of plasmonic near field plate at optical frequency
Authors: Shi Haofei , Jay Guo L.
Published: April 2010

We propose a design of near field plate for deep subwavelength super-focusing at optical frequency. The method used antisymmetric surface plasmon mode to generate abrupt π phase change within small fraction of a wavelength, while varied thin metallic film thickness to control the amplitude profile of the near field distribution. The numerical simulation result shows a λ/5 resolution at focus plane for the designed near field plate at the wavelength of 1550 nm, which is due to the superposition of the near field phase and amplitude distribution.
Evidence of electrical activity of extended defects in 3C–SiC grown on Si
Authors: Song X. , Michaud J. F. , Cayrel F. , Zielinski M. , Portail M. , Chassagne T. , Collard E. , Alquier D.
Published: April 2010

In this paper, we demonstrate the high electrical activity of extended defects found in 3C–SiC heteroepitaxially grown layer on (100) silicon substrates. Cross-sectional scanning transmission electron microscopy analysis was performed to reveal the defects while scanning spreading resistance microscopy aimed to study their electrical behavior. Using this technique, complete layer resistance cartography was done. The electrical activity of the extended defects in 3C–SiC was clearly evidenced. Furthermore, the defect activity was estimated to be higher than that of heavily nitrogen doped (5×1018 cm−3) 3C–SiC layer.
Correlation of oxygen vacancy concentration and thermoelectric properties in Na0.73CoO2−δ
Authors: Tsai P. H. , Norby T. , Tan T. T. , Donelson R. , Chen Z. D. , Li S.
Published: April 2010

In this work, oxygen vacancies were precisely controlled by manipulating oxygen partial pressure and the oxygen partial pressure dependence of thermoelectric properties of polycrystalline Na0.73CoO2−δ was investigated. The results suggest that resistivity and thermopower augment simultaneously with increasing concentration of oxygen vacancies δ due to the recombination of electrons and holes and average Co valence state. The total thermal conductivity can be reduced by minimizing δ. The dimensionless figure of merit was strongly affected by δ at lower operating temperature. The experimental results provide guideline for the variation in performance of this material system under different processing and operating environments.
International Equations for the Saturation Properties of Ordinary Water Substance. Revised According to the International Temperature Scale of 1990. Addendum to J. Phys. Chem. Ref. Data 16, 893 (1987)
Authors: Wagner Wolfgang , Pruss A.
Published: April 2010

Consistent with the latest experimental data and the internationally recommended values for the critical parameters we published in 1987, compact and accurate correlation equations are given for the following properties on the saturation line of ordinary (light) water substance: vapor pressure, density, and enthalpy and entropy of both the saturated liquid and the saturated vapor. As an addendum to a paper by A. Saul and W. Wagner, J. Phys. Chem. Ref. Data 16, 893 (1987), this paper brings all temperature values and adjusted coefficients in all correlation equations into agreement with the International Temperature Scale of 1990 (ITS-90). The new equations form the basis of the ‘‘Revised Supplementary Release on Saturation Properties of Ordinary Water Substance’’ issued by the International Association for the Properties of Water and Steam (IAPWS). This revised release which contains all equations and coefficients adjusted with regard to the ITS-90 is the main part of this paper.
Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 3. Mohair and wool production and quality
Authors: McGregor B. A.
Published: April 2010

The effects of animal species (AS; Angora goats, Merino sheep, mixed-grazed goats and sheep at the ratio of 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on fibre production and quality were determined in a replicated experiment on improved annual temperate pastures in southern Australia from 1981 to 1984. Separately grazed sheep produced the most total clean fibre/ha at each SR. Mixed-grazed treatments produced amounts of clean fibre/ha similar to the arithmetic mean of sheep and goat treatments at 7.5/ha (21.9 versus 21.3 kg/ha), 10% more at 10/ha (28.3 versus 25.3 kg/ha, P < 0.05) and 7% more at 12.5/ha (31.6 versus 29.6 kg/ha, P < 0.10). Clean wool production/head was affected by AS and SR but not year. Clean mohair production was affected by SR and year but not AS. Variation in mean fibre diameter (MFD) accounted for 67 and 71%, respectively, of the variation in clean wool and clean mohair production/head. There was an AS × SR interaction for clean fibre production/t pasture. Growth rate of mohair was highest in autumn and least in summer. In each season, an increase in the SR reduced the clean mohair growth rate. Growth rate of wool was highest in spring and least in summer. Wool and mohair MFD were affected by an AS × SR interaction. Mohair MFD was also affected by year and season. At 10/ha, wool from mixed-grazed sheep had a greater MFD than wool from separately grazed sheep (20.2 versus 18.9 μm) and mixed-grazed goats grew mohair 1 μm coarser than separately grazed goats. At 12.5/ha mixed-grazed goats grew mohair 1.9 μm finer than separately grazed goats. Mohair MFD was predicted by a multiple regression that included average liveweight for the period of fleece growth, season of growth (summer 1 µm finer than winter) and year (range 1.27 µm). Mohair MFD increased 4.7 µm/10 kg increase in average fleece-free liveweight (P = 6.4 × 10–14). Fleece-free liveweight alone accounted for 76.4% of the variation in mohair MFD. There was an AS × SR interaction for the incidence of kemp and medullated fibres; under severe grazing pressure their incidence was suppressed. This experiment indicated that the principles associated with the effects of SR on wool production on annual temperate pastures apply to mohair production. Mixed grazing of Merino sheep and Angora goats produced complementary and competitive effects depending on the SR. Angora goats should not be grazed alone or mixed-grazed with sheep on annual temperate pastures at SR greater than that recommended for Merino sheep.
Ventilatory frequency as a measure of the response of tammar wallabies (Macropus eugenii) to the odour of potential predators
Authors: Mella Valentina S. A. , Cooper Christine E. , Davies Stephen J. J. F.
Published: April 2010

This study uses changes in ventilatory frequency to quantify the physiological response of an Australian terrestrial herbivore, the tammar wallaby (Macropus eugenii), to olfactory cues suggesting the presence of potential predators. Ventilatory frequency proved to be a quantifiable measure to assess the response of this macropod marsupial to olfactory cues. Ventilatory frequency increased from mean resting levels of 45 ± 5.1 breaths min–1 to 137 ± 11.2 breaths min–1 during the first minute of exposure to all odours. These physiological responses diminished over time, with ventilatory frequency in the first minute after introduction of the scents greater than that during the subsequent four, suggesting that the initial reaction was due to disturbance and was investigative in nature. However, the ratio of ventilatory frequency in the remaining 4 min after introduction of the odours compared with before was greater for fox (3.58 ± 0.918) and cat (2.44 ± 0.272) odours than for snake (2.27 ± 0.370), distilled water (1.81 ± 0.463) and quoll (1.71 ± 0.245) odours, suggesting that fox and cat odour provoked a greater response. However, the wallabies’ response to the odour of these introduced predators and to horse odour (2.40 ± 0.492) did not differ. Our study indicates that a long period of co-history with particular predators is not a prerequisite for detection of potentially threatening species. We do not find any support for the hypothesis that an inability to interpret olfactory cues to detect and respond to potential predation by introduced predators is responsible for the decline of these macropod marsupials.
Molar crests and body mass as dietary indicators in marsupials
Authors: Hogue Aaron S. , ZiaShakeri Shakila
Published: April 2010

The discovery of ecomorphological relationships in mammals is important not only in its own right, but also for its potential in shedding light on the ecology of extinct and poorly known species. Two such potential relationships are the proposed connection between molar shear crests and body mass to diet. Research on primates suggests that, owing to the digestive challenges of structural carbohydrates (in foliage and insects), folivores and insectivores differ from other species in needing relatively long molar shear crests. These studies also suggest that metabolic constraints force folivores to be consistently larger than insectivores, with 500–700 g being the proposed body mass boundary between the two. This study tests these proposed ecomorphological links in a diverse sample of 64 marsupial species. As predicted, folivores and insectivores have significantly relatively longer molar shear crests than other species. Similarly, folivores are significantly larger than insectivores, as predicted, though the proposed body mass boundary was not supported. These results suggest that shear crest length and body mass are indeed linked to diet in the proposed manner. It may now be possible to use these findings to gain a greater understanding of the feeding behaviours of a variety of extinct marsupials and other therians.
Validating variation in radio-signal strength as an index of aquatic fauna activity
Authors: Thiem Jason D. , Ebner Brendan C. , Clear Rhian C.
Published: April 2010

Studying biological rhythms of activity and determining the external factors that influence behaviour of animals can be challenging in many aquatic habitats. We investigated the validity of using variations in radio-signal strength to quantify changes in activity of radio-tagged aquatic fauna on a small spatial scale under controlled conditions in the field. We monitored short-term activity (<1 min) of two aquatic species, rainbow trout (Oncorhynchus mykiss) and Murray River crayfish (Euastacus armatus), that differ markedly in their primary mode of movement. Simultaneous video monitoring confirmed that active and inactive periods for both species could be accurately determined by radio-telemetry, as were specific behaviours exhibited by trout. We were also able to quantify activity based on different radio-tag (coil and trailing whip antennas) and receiving antenna configurations (yagi and gap-loop antennas); however, we recommend use of control tags to provide reference data. Variation in radio-signal strength represents a valid means of monitoring activity of moderately site-attached aquatic species.
Potential Role of Active Surveillance in the Control of a Hospital-Wide Outbreak of Carbapenem-Resistant Klebsiella pneumoniae Infection
Authors: Ben-David Debby , Maor Yasmin , Keller Nathan , Regev-Yochay Gili , Tal Ilana , Shachar Dalit , Zlotkin Amir , Smollan Gill , Rahav Galia
Published: April 2010

Background.

The recent emergence of carbapenem resistance among Enterobacteriaceae is a major threat for hospitalized patients, and effective strategies are needed.

Objective.

To assess the effect of an intensified intervention, which included active surveillance, on the incidence of infection with carbapenem-resistant Klebsiella pneumoniae.

Setting.

Sheba Medical Center, a 1,600-bed tertiary care teaching hospital in Tel Hashomer, Israel.

Design.

Quasi-experimental study.

Methods.

The medical records of all the patients who acquired a carbapenem-resistant K. pneumoniae infection during 2006 were reviewed. An intensified intervention was initiated in May 2007. In addition to contact precautions, active surveillance was initiated in high-risk units. The incidence of clinical carbapenem-resistant K. pneumoniae infection over time was measured, and interrupted time-series analysis was performed.

Results.

The incidence of clinical carbapenem-resistant K. pneumoniae infection increased 6.42-fold from the first quarter of 2006 up to the initiation of the intervention. In 2006, of the 120 patients whose clinical microbiologic culture results were positive for carbapenem-resistant K. pneumoniae, 67 (56%) developed a nosocomial infection. During the intervention period, the rate of carbapenem-resistant K. pneumoniae rectal colonization was 9%. Of the 390 patients with carbapenem-resistant K. pneumoniae colonization or infection, 204 (52%) were identified by screening cultures. There were a total of 12,391 days of contact precautions, and of these, 4,713 (38%) were added as a result of active surveillance. After initiation of infection control measures, we observed a significant decrease in the incidence of carbapenem-resistant K. pneumoniae infection.

Conclusions.

The use of active surveillance and contact precautions, as part of a multifactorial intervention, may be an effective strategy to decrease rates of nosocomial transmission of carbapenem-resistant K. pneumoniae colonization or infection.
Drift-Alfvén vortex structures in the edge region of a fusion relevant plasma
Authors: Vianello N. , Spolaore M. , Martines E. , Cavazzana R. , Serianni G. , Zuin M. , Spada E. , Antoni V.
Published: April 2010

Edge turbulent structures are commonly observed in fusion devices and are generally believed to be responsible for confinement degradation. Among their origin drift-Alfvén turbulence is one of the most commonly suggested. The drift-Alfvén paradigm allows the existence of localized vortex-like structures observed also in various systems. Here we present the evidence of the presence of drift-Alfvén vortices in the edge region of RFX-mod reversed field pinch device, showing how these structures are responsible for electromagnetic turbulence at the edge and its intermittent nature.
Energy identity for approximations of harmonic maps from surfaces
Authors: Lamm Tobias
Published: April 2010

We prove the energy identity for min-max sequences of the Sacks-Uhlenbeck and the biharmonic approximation of harmonic maps from surfaces into general target manifolds. The proof relies on Hopf-differential type estimates for the two approximations and on estimates for the concentration radius of bubbles.