bluuebunny/crossref_metadata_2025 huggingface dataset:
USArray observations of quasi‐Love surface wave scattering: Orienting anisotropy in the Cascadia plate boundary
Authors: Rieger D. M. , Park J.
Published: May 2010

Quasi‐Love (QL) surface wave anomalies are observed along multiple great circle paths crossing the Pacific and through the mid‐ocean ridge and subduction zone associated with the Juan de Fuca plate. The long‐period QL waves observed on the USArray component of EarthScope arrive immediately after the fundamental Love wave arrival, suggesting that the QL waves were generated close to USArray and near the plate boundary. The dense USArray network allows the analysis of the azimuthal dependence of the QL surface wave scattering to determine the horizontal anisotropic axes of symmetry in Earth's upper mantle. We focus on the location, 42.5°N and 127.5°W just offshore of the southern Oregon coastline near the Gorda Ridge, and we analyze the QL scattering along 14 different great circle paths crossing through this location. We low‐pass filter the data to suppress overtones and crustal effects. QL amplitude and polarity constrains an anisotropic axis of symmetry that correlates well with the hot spot referenced Juan de Fuca plate motion and regional shear wave splitting. QL observations at multiple periods (50, 75, 100, 150, and 200 s) suggest a maximum Love‐to‐Rayleigh scattering at 100 s period, which is consistent with anisotropic lateral gradients in the asthenosphere beneath the Juan de Fuca and Gorda plates. Our observations do not follow the predictions of slab rollback and suggest the entrainment of asthenosphere with the overriding Juan de Fuca and Gorda plates.
Repeat temperature measurements in boreholes from northwestern Utah link ground and air temperature changes at the decadal time scale
Authors: Davis Michael G. , Harris Robert N. , Chapman David S.
Published: May 2010

Borehole temperature profiles provide a record of ground surface temperature (GST) change at the decadal to centennial time scale. GST histories reconstructed from boreholes are particularly useful in climate reconstruction if changes in GST and surface air temperature (SAT) are effectively coupled at decadal and longer time periods and it can be shown that borehole temperatures respond faithfully to surface temperature changes. We test these assumptions using three boreholes in northwestern Utah that have been repeatedly logged for temperature over a time span of 29 years. We report 13 temperature‐depth logs at the Emigrant Pass Observatory borehole GC‐1, eight at borehole SI‐1 and five at borehole DM‐1, acquired between 1978 and 2007. Systematic subsurface temperature changes of up to 0.6°C are observed over this time span in the upper sections of the boreholes; below approximately 100 m any temperature transients are within observational noise. We difference the temperature logs to highlight subsurface transients and to remove any ambiguity resulting from steady state source of curvature. Synthetic temperature profiles computed from SAT data at nearby meteorological stations reproduce both the amplitude and pattern of the transient temperature observations, fitting the observations to within 0.03°C or better. This observational confirmation of the strong coupling between surface temperature change and borehole temperature transients lends further support to the use of borehole temperatures to complement SAT and multiproxy reconstructions of climate change.
Reconstructing surface temperature changes over the past 600 years using climate model simulations with data assimilation
Authors: Goosse H. , Crespin E. , de Montety A. , Mann M. E. , Renssen H. , Timmermann A.
Published: May 2010

Ensemble simulations have been performed with a climate model constrained to follow temperature histories obtained from a recent compilation of 56 well‐calibrated surface temperature proxy records, using a new data assimilation technique. First, we demonstrate that the data assimilation technique provides a faithful representation in the Northern Hemisphere of the signal recorded by the climate proxies at both the regional and gridbox scales. Second, by varying the external forcing, the parameters of the data assimilation method, and the parameters controlling the equilibrium climate sensitivity of the climate model, we demonstrate that the uncertainty in model results is much lower in simulations using data assimilation than in those without it. This observation implies that the data assimilation, using a set of 56 proxies, is providing an efficient and robust constraint on the simulated climate variability over the past centuries. At the hemispheric and continental scales, the model reconstructions using data assimilation are in good agreement with both the instrumental record of the past 150 years and reconstructions of climate in past centuries derived from the application of traditional statistical approaches to networks of proxy data. This increases the confidence in both the data assimilation and traditional statistical approaches. Our data assimilation method, however, is unable to provide a reliable reconstruction over the North Atlantic Ocean, which we attribute to the paucity of proxy data in that region.
GLGM‐3: A degree‐150 lunar gravity model from the historical tracking data of NASA Moon orbiters
Authors: Mazarico E. , Lemoine F. G. , Han Shin‐Chan , Smith D. E.
Published: May 2010

In preparation for the radio science experiment of the Lunar Reconnaissance Orbiter (LRO) mission, we analyzed the available radio tracking data of previous NASA lunar orbiters. Our goal was to use these historical observations in combination with the new low‐altitude data to be obtained by LRO. We performed Precision Orbit Determination on trajectory arcs from Lunar Orbiter 1 in 1966 to Lunar Prospector in 1998, using the GEODYN II program developed at NASA Goddard Space Flight Center. We then created a set of normal equations and solved for the coefficients of a spherical harmonics expansion of the lunar gravity potential up to degree and order 150. The GLGM‐3 solution obtained with a global Kaula constraint (2.5 × 10−4l−2) shows good agreement with model LP150Q from the Jet Propulsion Laboratory, especially over the nearside. The levels of data fit with both gravity models are very similar (Doppler RMS of ∼0.2 and ∼1–2 mm/s in the nominal and extended phases, respectively). Orbit overlaps and uncertainties estimated from the covariance matrix also agree well. GLGM‐3 shows better correlation with lunar topography and admittance over the nearside at high degrees of expansion (l> 100), particularly near the poles. We also present three companion solutions, obtained with the same data set but using alternate inversion strategies that modify the power law constraint and expectation of the individual spherical harmonics coefficients. We give a detailed discussion of the performance of this family of gravity field solutions in terms of observation fit, orbit quality, and geophysical consistency.
Effects of sea ice on atmospheric pCO2: A revised view and implications for glacial and future climates
Authors: Sun Xiaoting , Matsumoto Katsumi
Published: May 2010

Sea ice is a key component in the global carbon cycle and climate system. In the traditional view, the sole effect of expanded sea ice coverage is to reduce the atmospheric pCO2 by inhibiting air‐sea gas exchange. However, this view neglects the effect that sea ice capping has on the biological production. By limiting light for photosynthesis, larger sea ice coverage would reduce the strength of the biological pump and therefore increase atmospheric pCO2. Recently, Kurahashi‐Nakamura et al. (2007) suggested that the opposing impact of biology on atmospheric pCO2 will more than offset the gas exchange effect, such that atmospheric pCO2 will actually increase with larger sea ice coverage. In an effort to resolve this controversy, we use an intermediate‐complexity, global model of biogeochemistry and climate to determine the sensitivity of atmospheric CO2 concentration to changes in the sea ice coverage, driven by prescribed changes in sea ice albedo. When sea ice in our model is increased by 34% globally relative to the control run, gas solubility, ice capping effect and stratification increase, while biological production decreases; overall atmospheric pCO2 is reduced by 9.4 ppmv. Our results broadly support the notion that the biological response of sea ice capping is as important as its physical response. Furthermore, we show that the overall change in atmospheric pCO2 is indeed inversely related to sea ice coverage, but it is not because sea ice caps off gas exchange but because gas solubility is increased by lower temperatures that accompany sea ice expansion in our model simulations.
Diagnosis of tropical cyclone activity through gravity wave energy density in the southwest Indian Ocean
Authors: Ibrahim C. , Chane‐Ming F. , Barthe C. , Kuleshov Y.
Published: May 2010

Tropical cyclone (TC) activity is diagnosed through convective gravity waves (GWs) observed in the upper troposphere (UT)/lower stratosphere (LS) above Tromelin island (15.53°S, 54.31°E) in the tropical southwest Indian Ocean. Monthly and weekly GW total energy densities derived from daily GPS windsonde data are compared with Outgoing Longwave Radiation (OLR) and TC hours in the vicinity of Tromelin. A relationship between GW energy density and TC activity is observed in the LS, for the TC season 2001/2002. Moreover TCs (local convection) produce GWs with total energy density mostly higher (lower) than 12 J kg−1. A 10‐season climatology (1997/1998–2006/2007) confirms that large values of GW total energy density in the LS are associated with weak values of OLR during the TC passage. Monthly total, kinetic and potential GW energy densities within 2000 km radius of Tromelin can be estimated using linear relationships with TC hours for a threshold of above 6 TC days per month. A linear relationship also exists between weekly GW total energy density in the LS and the activity of intense TCs above a threshold of 2 TC days per week within 1000 km radius of Tromelin. GW energy density in the LS could be used as a possible index to investigate TC activity in the UT/LS.
Equatorial ionospheric bubble precursor
Authors: Keskinen M. J.
Published: May 2010

A time‐dependent nonlinear three‐dimensional model for the evolution of the equatorial bottomside lower ionosphere in the presence of dissipating gravity waves has been developed. From the numerical solution of the model, it is found that large bottomtype F‐region ionospheric density perturbations and electric fields can be driven by dissipating gravity waves from tropospheric sources. The spatial distribution of the ionospheric F‐region density perturbations can be characterized as a patchy, layer‐like structure and may be responsible, in part, for observed large scale wavelike structures in the equatorial bottomside F‐region which are a precursor to fully developed equatorial ionospheric bubbles. Favorable comparison of the model with observations is made.
Physical mechanism of long‐term drying trend over tropical North Africa
Authors: Kawase Hiroaki , Abe Manabu , Yamada Yukiko , Takemura Toshihiko , Yokohata Tokuta , Nozawa Toru
Published: May 2010

Based on an approximated moisture budget equation, we investigate the physical mechanisms of a drying trend observed over tropical North Africa in the boreal summer during the 20th Century by analyzing datasets of several climate‐model experiments forced with various combinations of natural and anthropogenic forcings. Increased anthropogenic aerosols thermodynamically induce a drying trend due to a tropospheric cooling and dynamically induce an additional drying trend due to an atmospheric local circulation change stirred up by the strong gradient of a sea surface temperature anomaly over the tropical Atlantic Ocean. Increased greenhouse gases, on the other hand, induce a drying trend through the large‐scale dynamic effect, which is canceled out by the thermodynamically induced moistening trend due to tropospheric warming. Therefore, the drying trend observed over tropical North Africa during the 20th Century is strongly affected by the increased anthropogenic aerosols through both the dynamic and thermodynamic effects.
Why do equatorial ionospheric bubbles stop rising?
Authors: Krall J. , Huba J. D. , Ossakow S. L. , Joyce G.
Published: May 2010

The Naval Research Laboratory (NRL) three‐dimensional simulation code SAMI3/ESF is used to study the long time evolution of equatorial spread F (ESF) bubbles. The ESF bubbles are modeled until they stop rising and become “fossils,” with results analyzed to address previously‐untested hypotheses. Specifically, it has been suggested that bubbles stop rising when either the local electron density inside the bubble is equal to that of the nearby background or the flux‐tube‐integrated electron density inside the bubble is equal to that of the nearby background. It is shown that equatorial bubbles stop rising when the magnetic flux‐tube‐integrated ion mass density inside the bubble equals that of the surrounding background ionosphere. In the case of a single‐ion ionosphere this reduces to the condition that the flux‐tube‐integrated electron densities are in balance, consistent with the hypothesis of Mendillo et al. (2005).
Detection systems cross reacting with peptides - Analysis at the amino acid level
Authors: Mahrenholz Carsten , Tapia Victor , Stigler Rolf , Volkmer Rudolf
Published: May 2010

There are several methods commonly used to measure protein-protein interactions and binding affinities. Quite contrary to most of these methods, protein- and peptide arrays on cellulose membranes or glass slides are suitable for high-throughput measurement, as they provide a higher density of probes and a multitude of peptide-protein interactions can be measured in parallel [1]. The most important application of the SPOT synthesis technique is to simultaneously detect a high number of peptides that have a strong binding affinity to defined targets. The validity of the results, however, depends on the ability of the detection system to indicate binding events whilst not interfering with the experiment itself through cross reaction. We tested three common peptide detection systems (TAMRA, FITC, Biotin/ Streptavidine) for their ability to interact with cellulose bound peptides at the amino acid level. Peptides with different amino acid cores were synthesized and tested for interaction with common dyes and detection systems. Our goal was to discover the potential of 5-(and 6)-carboxytetramethylrhodamine [5(6)-TAMRA], fluoresceinisothiocyanate [FITC], biotin and streptavidine to crossreact with individual amino acids. To this end we designed 20 peptides of the sequence XXX[aa]5XXX, where [aa]5 denotes five repeats of one of the 20 amino acids, and prepared them via SPOT synthesis [2]. Glycine was chosen as the flanking residue X to act as a spacer molecule. As analytes small peptides (gly-gly-gly) were solid phase synthesized and afterwards labelled with the detection compound of interest. The resulting amino acid library was then incubated with the glycine labelled detection system and evaluated via optical and fluorescent methods.Our approach identified several amino acids interacting with different detection systems. These results will strengthen the reliability of the analysis of SPOT synthesis generated data in the future.

References

1.Andresen, H. et al. Functional peptide microarrays for specific and sensitive antibody diagnostics. Proteomics, 6(5):1376– 1384, Mar 2006.2.Frank, R. The spot-synthesis technique. Synthetic peptide arrays on membrane supports – principles and applications. J Immunol Methods, 267(1):13–26, 2002.
Simultaneous inhibition of TXA2 and PGI2 synthesis increases NO release in mesenteric resistance arteries from cirrhotic rats
Authors: Xavier Fabiano E. , Blanco-Rivero Javier , Sastre Esther , Badimón Lina , Balfagón Gloria
Published: May 2010

Our present study examines, in mesenteric resistance arteries, possible vasodilation alterations, and the role of NO and COX (cyclo-oxygenase) derivatives, in cirrhosis. The vasodilator response to acetylcholine was analysed in segments from control and cirrhotic rats. The effects of the non-specific COX inhibitor indomethacin, the specific COX-1 inhibitor SC-560 and the specific COX-2 inhibitor NS-398 were analysed in segments from both groups of rats. NO release was measured, and eNOS [endothelial NOS (NO synthase)], phospho-eNOS, iNOS (inducible NOS), COX-1 and COX-2 protein expression was also analysed. The effects of the TP receptor [TXA2 (thromboxane A2) receptor] antagonist SQ 29548, the TXA2 synthesis inhibitor furegrelate, the PGI2 (prostaglandin I2) synthesis inhibitor TCP (tranylcypromine) or TCP+furegrelate were only determined in segments from cirrhotic rats. The vasodilator response to acetylcholine was higher in segments from cirrhotic rats. Indomethacin, SC-560 and NS-398 did not modify the vasodilator response in control rats; however, indomethacin, NS-398 and TCP+furegrelate increased, whereas SC-560 did not modify and SQ 29548, furegrelate or TCP decreased, the vasodilator response to acetylcholine in cirrhotic rats. NO release was higher in cirrhotic rats. Furegrelate decreased, whereas TCP+furegrelate increased, the NO release in segments from cirrhotic rats. eNOS and COX-1 protein expression was not modified, whereas phosho-eNOS, iNOS and COX-2 protein expression was higher in cirrhotic rats. Therefore the increase in iNOS expression and eNOS activity may mediate increases in endothelial NO release. The COX-2 derivatives TXA2 and PGI2 may act simultaneously, producing a compensatory effect that reduces NO release and may limit the hyperdynamic circulation.
Differential pulsed eddy current sensor for the detection of wall thinning in an insulated stainless steel pipe
Authors: Angani C. S. , Park D. G. , Kim G. D. , Kim C. G. , Cheong Y. M.
Published: May 2010

A differential probe which is used in the pulsed eddy current (PEC) system has been fabricated for the detection of wall thinning of insulated pipelines in a nuclear power plant (NPP). The differential PEC probe consists of two hall sensors in a differential arrangement. The tested sample is a stainless steel of thickness variation from 1 to 5 mm, the flat side of the sample is laminated by a plastic insulation having a uniform thickness to simulate the pipelines in NPP. The PEC response to varying metal thickness was measured at various thicknesses of insulations on the tested sample. The time-domain feature such as peak value of the detected pulse is used to interpret the thickness of the test sample. The signal analysis technique, such as power spectrum density, is applied to obtain an optimum parameter to describe the wall thinning of pipeline steel. This technique can be used as a potential tool to detect the corrosion or the wall thinning of the pipelines without removing the insulation.
Impact of size mismatch induced quenched disorder on phase fluctuation and low field magnetotransport in polycrystalline Nd0.58−xGdxSr0.42MnO3
Authors: Srivastava Manoj K. , Prasad Ravikant , Siwach P. K. , Singh M. P. , Singh H. K.
Published: May 2010

We report the magnetic and transport properties of polycrystalline Nd0.58−xGdxSr0.42MnO3 (x∼0.0, 0.04, 0.08, 0.12, 0.16, 0.20, 0.25, 0.30, 0.35, and 0.42). All the samples are single phase and have grain size ∼1–2 μm. As the variance σ2 increases, the paramagnetic-ferromagnetic transition shows a gradual decrease and broadening, while the decrease in insulator metal transition is sharpened. However, near equality of TC and TIM at intermediate values of σ2 could be understood in terms of the competing quenched and the grain boundary disorder. The variation in peak magnetoresistance (MR) (maximum MR around TC/TIM) with σ2 shows that maximum low field MR≈35% at H=3 kOe (68% at H=10 kOe) is centered around σ2=0.009 857 Å2 (x=0.25). This shows that huge intrinsic MR can be obtained at relatively higher temperatures and lower magnetic fields in the region of enhanced phase fluctuations.
Phase transition in the magnetic field in a Bose gas
Authors: Poluéktov Yu. M. , Volosnev A. G.
Published: May 2010

The thermodynamic properties of a Bose gas of particles with nonzero spin and magnetic moment in states with and without a Bose-Einstein condensate are studied as a function of the external magnetic field. It is shown that there exists a temperature interval where a transition into a state with a Bose-Einstein condensate occurs in a Bose gas with constant temperature and particle number density when the magnetic field is increasing and reaches a critical magnitude. The temperature and magnetic field derivatives of the specific heat at constant volume and the magnetic susceptibility undergo a jump at such a transition.
Charge transfer along localized states in InSe and InSe⟨Sn⟩ single crystals
Authors: Mustafaeva S. N. , Ismaĭlov A. A. , Asadov M. M.
Published: May 2010

It is established that at temperatures T<200K hopping conductivity with variable hopping length exists across natural layers of undoped and doped (0.2 and 0.4at% Sn) InSe single crystals in a constant electric field. The density of states near the Fermi level (NF=5.36⋅1018–1.72⋅1019eV−1⋅cm−3), the energy spread of the states (ΔE=0.028–0.040eV), the localization radius (a=58Å), and the average hopping length (Rav=99.5–130Å) in the temperature interval 100–200K are evaluated.
New mechanism of the formation of vacancy voids
Authors: Devyatko Yu. N. , Khomyakov O. V. , Kagan M. Yu.
Published: May 2010

A new mechanism is proposed for the formation of vacancy voids in irradiated metal as being due to the successive development of two types of instabilities in a system of interacting point defects produced by neutron irradiation. The first stage of the void formation process involves the nucleation of local vacancy clusters possessing a high, relative to the surroundings, concentration of defects; the second state involves lattice instability inside such clusters.
Low-frequency vibrational spectrum of a KYb(MoO4)2 crystal
Authors: Bondar’ N. S. , Poperezhaĭ S. N. , Kut’ko V. I.
Published: May 2010

The long-wavelength IR transmission spectra of a KYb(MoO4)2 crystal in the spectral range 10–40cm−1 at low temperatures T=6K are measured in polarized light. Two vibrational modes with energies 16.8cm−1 (E∥a) and 25.3cm−1 (E∥c) are found. The structure of the low-frequency vibrational spectrum in the Brillouin zone is calculated using a one-dimensional model.
Isothermal slip of a quantum Bose gas with specular-diffuse reflection from the boundary
Authors: Kvashnin A. Yu. , Latyshev A. V. , Yushkanov A. A.
Published: May 2010

A solution is obtained for Kramers’ problem of isothermal slip of a quantum Bose gas along a flat solid surface. The reflection of molecules from the wall is assumed to be specular-diffuse. A model kinetic equation with a collision integral in the τ-model form and collision frequency proportional to the molecular velocity is used. The dependence of the slip velocity on the value of a parameter equal to the ratio of the chemical potential to the product of Boltzmann’s constant by the absolute temperature is analyzed.
Phase diagram of a tetrahedral patchy particle model for different interaction ranges
Authors: Romano Flavio , Sanz Eduardo , Sciortino Francesco
Published: May 2010

We evaluate the phase diagram of the Kern–Frenkel patchy model with four interaction sites for four different values of the radial interaction range (all in the single-bond-per-patch regime) keeping the area of the interaction patches fixed. Four stable crystal phases are investigated, namely diamond cubic (DC), bcc, fcc, and plastic fcc. The DC is favored at low temperatures and pressures, while the bcc is favored at low temperatures and intermediate to high pressures. At low temperatures and very high pressures an ordered fcc phase is found, while—as expected—at high temperatures, the only stable crystal is a plastic fcc phase. We find a rich phase diagram with several re-entrant coexistence lines, which can be brought in the equilibrium phase diagram by a proper choice of the range. We also show that the gas-liquid phase separation becomes metastable as the range narrows, and it takes place in a region of the phase diagram where the low density diamond crystal is the thermodynamically stable phase.
Acceleration to high velocities and heating by impact using Nike KrF laser
Authors: Karasik Max , Weaver J. L. , Aglitskiy Y. , Watari T. , Arikawa Y. , Sakaiya T. , Oh J. , Velikovich A. L. , Zalesak S. T. , Bates J. W. , Obenschain S. P. , Schmitt A. J. , Murakami M. , Azechi H.
Published: May 2010

The Nike krypton fluoride laser [S. P. Obenschain, S. E. Bodner, D. Colombant, et al., Phys. Plasmas 3, 2098 (1996)] is used to accelerate planar plastic foils to velocities that for the first time reach 1000 km/s. Collision of the highly accelerated deuterated polystyrene foil with a stationary target produces ∼Gbar shock pressures and results in heating of the foil to thermonuclear temperatures. The impact conditions are diagnosed using DD fusion neutron yield, with ∼106 neutrons produced during the collision. Time-of-flight neutron detectors are used to measure the ion temperature upon impact, which reaches 2–3 keV.
Evolution of the air cavity during a depressurized wave impact. I. The kinematic flow field
Authors: Lugni C. , Miozzi M. , Brocchini M. , Faltinsen O. M.
Published: May 2010

This paper describes a systematic experimental study of the role of the ambient pressure on wave impact events in depressurized environments. A wave impact event of “mode (b)” [see Lugni et al., “Wave impact loads: The role of the flip-through,” Phys. Fluids 18, 122101 (2006)] causes entrapment of an air cavity. Here the topological and kinematic aspects of its oscillation and evolution toward collapse into a mixture of water and air bubbles are studied, while Part II [Lugni et al., “Evolution of the air cavity during a depressurized wave impact. II. The dynamic field,” Phys. Fluids 22, 056102 (2010)] focuses on the dynamic features of the flow. Four distinct stages characterize the flow evolution: (1) the closure of the cavity onto the wall, (2) the isotropic compression/expansion of the cavity, (3) its anisotropic compression/expansion, and (4) the rise of the cavity up the wall. The first two stages are mainly governed by the air leakage, the last two by the surrounding hydrodynamic flow, which contributes to compressing the bubble horizontally and to convecting it up the wall. Ullage pressure affects the ratio between the minimum and maximum cavity areas. An ullage pressure of 2.5% of the atmospheric pressure leads to an area ratio of about 360% of the equivalent ratio at atmospheric conditions.
Evolution of the air cavity during a depressurized wave impact. II. The dynamic field
Authors: Lugni C. , Brocchini M. , Faltinsen O. M.
Published: May 2010

The present paper on wave-impact events in depressurized environments completes the analysis of Part I by focusing on the dynamical features of the impacts and on the influence of the ambient pressure. Connection is made between the impact regimes typically described in the literature and the stages described in Part I [C. Lugni, M. Miozzi, M. Brocchini, and O. M. Faltinsen, “Evolution of the air cavity during a depressurized wave impact. I. The kinematic flow field,” Phys. Fluids 22, 056101 (2010)]. The stages of isotropic/anisotropic compression and expansion of the air cavity are of particular interest. The impact duration at the wall is almost independent of its height above the undisturbed surface level, but its intensity rapidly decreases in the body of the fluid (the peak pressure halves within the first two compression/expansion cycles). The time evolution of the pressure loads on the wall is analyzed by means of the Hilbert transform and an empirical mode decomposition of the signals. This enables identification of the intrinsic mode functions which best fit the original signal during its evolution and quantification of the frequency downshifting which characterize the whole process. The pressure decay, largely governed by air leakage out of the cavity, is found to be very intense during the air cavity closure and the isotropic compression/expansion cycle [stages (1) and (2)]; the decay observed during stage (3), i.e., during the anisotropic compression/expansion cycles, is weaker and independent of the vertical location down the wall. Differences between the observed decay rates and those of a three-dimensional bubble in an infinite fluid are mainly due to the bubble being two-dimensional, being close to the free surface and loosing air. The role of both ullage and vapor pressures on the impact is described, respectively, by means of the Euler and cavitation numbers. The frequency of the bubble oscillation depends on these numbers in a way that is closely similar to that displayed by the bubble area, see Part I.
Absorption spectra of thin films of the solid solutions Rb2(Cd1−xZnx)I4
Authors: Miloslavskiĭ V. K. , Yunakova O. N. , Kovalenko E. N.
Published: May 2010

The excitonic absorption spectra of thin films of the solid solutions Rb2(Cd1−xZnx)I4 have been studied for the first time. It is determined that the spectra of the solid solutions are stable and consist of two bands which genetically originate from the initial bands of the compounds Rb2CdI4 and Rb2ZnI4. It is shown on the basis of the structure of the crystal lattices of the compounds that the concentration dependence of the spectral position of the excitonic bands AI and AII is related with the transfer of excitons between CdI4 and ZnI4 tetrahedra along the b axis of the solid solutions. The experimental result is in good agreement with the calculation of the energies EAI(x) and EAII(x) on the basis of a theory similar to the theory of Davydov splitting of excitonic bands in molecular crystals.
Structural signatures of mobility on intermediate time scales in a supercooled fluid
Authors: Krekelberg William P. , Ganesan Venkat , Truskett Thomas M.
Published: May 2010

We use computer simulations to explore the manner in which the particle displacements on intermediate time scales in supercooled fluids correlate to their dynamic structural environment. The fluid we study, a binary mixture of hard spheres, exhibits classic signatures of dynamic heterogeneity, including a bifurcated single-particle displacement distribution (i.e., subpopulations of immobile and mobile particles). We find that immobile particles, during the course of their displacements, exhibit stronger average pair correlations to their neighbors than mobile particles, but not necessarily higher average coordination numbers. We discuss how the correlation between structure and single-particle dynamics depends on observation time.
Rotational relaxation times of individual compounds within simulations of molecular asphalt models
Authors: Zhang Liqun , Greenfield Michael L.
Published: May 2010

The dynamical properties of a complex system incorporate contributions from the diverse components from which it is constituted. To study this relationship in a multicomponent system, relaxation times based on rotation autocorrelation functions in molecular dynamics simulations were analyzed for molecules in two sets of unmodified and polymer-modified model asphalt/bitumen systems over 298–473 K. The model asphalt systems were proposed previously to approximate the chemical and mechanical properties of real asphalts. Relaxations were modeled using a modified Kaulrausch–Williams–Watts function and were based on the third Legendre polynomial of normal vector time correlation functions for aromatic species (asphaltene, polar aromatic, naphthene aromatic). Both the end-to-end vector and the longest axis eigenvector of the radius of gyration matrix were used for time correlation functions of chain molecules (C22, polystyrene). Decreases in temperature induced large increases in relaxation time consistent with the Vogel–Fulcher–Tammann equation. The presence of a polymer slowed the decay of each correlation function to some extent. The product of relaxation time and diffusion coefficient revealed qualitative differences between larger and smaller molecules in the same system. These relaxation mechanisms remained coupled for small molecules, while the larger asphaltene and polymer molecules revealed significant slowdowns in rotation compared to translational diffusion at lower temperatures. Smaller values of the stretched exponential parameter β for asphaltenes compared to smaller molecules suggested a broader range of relaxation times and were consistent with this distinction. Difficulties in converging polymer chain relaxation times are discussed in terms of fluctuations in the magnitude and orientation of the end-to-end vector and chain axis eigenvector. Viscosity results suggested by the Debye–Stokes–Einstein relationship are consistent with trends shown in the literature for true bitumen systems.
Low-temperature behavior of the magnetoelastic characteristics of praseodymium ferroborate
Authors: Zvyagina G. A. , Zhekov K. R. , Bilych I. V. , Zvyagin A. A. , Bezmaternykh L. N. , Gudim I. A.
Published: May 2010

The behavior of the elastic moduli and sound absorption in a PrFe3(BO3)4 single crystal at low temperatures is studied. A transition of the magnetic subsystem into an antiferromagnetically ordered state is manifested in the temperature behavior of the sound velocities and absorption. The characteristic behavior of the elastic properties of PrFe3(BO3)4 in an external magnetic field is observed. A phenomenological theory that gives a qualitative description of the observed features is constructed. It is proposed that a weak magnetic moment exists in the crystal.
Two-parameter dynamical solitons in thin elastic plates
Authors: Kovalev A. S. , Sokolova E. S.
Published: May 2010

The dynamics of two-parameter elastic solitons with almost shear polarization, which are localized in a thin elastic plate consisting of an anharmonic material, is investigated. One-dimensional nonlinear integrodifferential equations for the shear displacements are derived and a variant of an asymptotic procedure making it possible to find approximate analytical solutions for such solitons is proposed.
On the linear instability of a finite Stokes layer: Instantaneous versus Floquet modes
Authors: Luo Jisheng , Wu Xuesong
Published: May 2010

The linear instability of a finite Stokes layer is investigated numerically. The aim is to clarify the relationship between the instantaneous instability and the recently discovered Floquet global instability [P. J. Blennerhassett and A. P. Bassom, J. Fluid Mech. 464, 394 (2002); P. J. Blennerhassett and A. P. Bassom, J. Fluid Mech. 556, 1 (2006)], and their role in causing transition to turbulence. For the first time, a numerical approach based on initial-value calculations is able to confirm the global instability, which occurs as the Reynolds number R (based on the Stokes-layer thickness) exceeds the critical value Rc=708. In both supercritical (R>Rc) and subcritical (R<Rc) regimes, strong instantaneous growth occurs during the deceleration phase. By projecting the disturbance at an arbitrary instant to instantaneous eigenfunctions, it is shown that the energy of the disturbance is primarily carried by the most unstable instantaneous mode. During the main growing phase, both the spatial structure and the growth rate agree well with those of the instantaneous mode; during the decaying phase part of the energy is continuously transferred to the precursor (i.e., the backward continuation in time) of the most unstable mode existing in the next cycle. The most unstable mode including its continuation therefore constitutes the crucial part of a Floquet mode. Unstable Floquet modes exist despite that none of instantaneous modes is periodic, implying that the commonly held premise that a Floquet mode is equivalent to a periodic instantaneous mode is erroneous. It is also found that in the subcritical regime, the flow responds very sensitively to small surface roughness, modeled by a wavy wall. The sensitivity can be measured by a response function, and our calculations show that significant disturbances can be generated by surface imperfections less than 0.1 μm in typical experimental setups. The response becomes stronger as R increases, and tends to infinity as the wavenumber of the wavy wall approaches that of the critical Floquet mode at Rc, indicating that roughness with a suitable wavelength can excite a global mode through resonance, and the large response may be attributed to a detuned resonance with a global mode.
Dual wavelength GaSb based type I quantum well mid-infrared light emitting diodes
Authors: Jung Seungyong , Suchalkin Sergey , Kipshidze Gela , Westerfeld David , Golden Eric , Snyder Donald , Belenky Gregory
Published: May 2010

We have designed and developed dual wavelength type I quantum well light emitting diodes (LEDs) operating at 2 μm and 3–3.4 μm wavelengths with independently controlled intensities. The room temperature quasicontinuous wave output power was 2.8 mW at 2 μm and 0.14 mW at 3 μm. The design of the dual wavelength structure allows for monolithically integrating LED pixels with different wavelengths opening the way for the fabrication of multiwavelength LED arrays for multispectral and hyperspectral imaging applications.
Charge generation layers comprising transition metal-oxide/organic interfaces: Electronic structure and charge generation mechanism
Authors: Meyer J. , Kröger M. , Hamwi S. , Gnam F. , Riedl T. , Kowalsky W. , Kahn A.
Published: May 2010

The energetics of an archetype charge generation layer (CGL) architecture comprising of 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), tungsten oxide (WO3), and bathophenanthroline (BPhen) n-doped with cesium carbonate (Cs2CO3) are determined by ultraviolet and inverse photoemission spectroscopy. We show that the charge generation process occurs at the interface between the hole-transport material (TCTA) and WO3 and not, as commonly assumed, at the interface between WO3 and the n-doped electron-transport material (BPhen:Cs2CO3). However, the n-doped layer is also essential to the realization of an efficient CGL structure. The charge generation mechanism occurs via electron transfer from the TCTA highest occupied molecular orbital level to the transition metal-oxide conduction band.
Exchange bias in single-crystalline CuO nanowires
Authors: Díaz-Guerra C. , Vila M. , Piqueras J.
Published: May 2010

Exchange anisotropy has been observed and investigated in single-crystalline CuO nanowires grown by thermal oxidation of Cu. The exchange bias field decreases by increasing temperature and can be tuned by the strength of the cooling field. A training effect has also been observed. The obtained results can be understood in terms of a phenomenological core-shell model, where the core of the CuO nanowire shows antiferromagnetic behavior and the surrounding shell behaves as a spin glass-like system due to uncompensated surface spins.
Large scale computer simulations of strain distribution and electron effective masses in silicon ⟨100⟩ nanowires
Authors: Tuma Christian , Curioni Alessandro
Published: May 2010

A multiscale method is proposed to analyze the internal redistribution of tensile strain applied to silicon ⟨100⟩ nanowires and its effect on electron effective masses m∗. Nonperiodic, realistic models of unprecedented size containing up to 2.2×107 atoms (652×26×26 nm3) allow the identification of nonuniform redistribution patterns specific to the constraints applied to impose external strain. Depending on how the external strain is imposed, silicon nanowires can show m∗ behavior similar to strained bulk silicon, or, as a function of nanowire size, can display intrinsic strain large enough that external strain hardly reduces m∗ further. For nanowire cross section sizes smaller than 8×8 nm2 quantum confinement leads to an increase in m∗ which cannot be compensated for by tensile strain.
Thermal kinetics of OH− ions in LiNbO3:Mg crystals above the photorefractive threshold
Authors: Lengyel K. , Kovács L. , Péter Á. , Polgár K. , Corradi G. , Baraldi A. , Capelletti R.
Published: May 2010

OH stretching vibrations in LiNbO3 (LN) crystals having various Li/Nb ratios and doped with Mg above the photorefractive threshold concentration were investigated in the 20–500 °C temperature range. Beside the 3534 cm−1 above-threshold band another peak at about 3465 cm−1, known from below-threshold stoichiometric LN, was found to appear at a temperature depending on the Mg surplus concentration and grow further with increasing temperature at the expense of the 3534 cm−1 band. The energy difference between the OH− ions was determined to be ΔE=0.25±0.02 eV independently from the composition and Mg concentration. A kinetic model describing the thermal process predicts a linear Mg surplus dependence of the ratio of band areas at a given temperature.
The effect of trapping superparamagnetic beads on domain wall motion
Authors: Bryan Matthew T. , Dean Julian , Schrefl Thomas , Thompson Faye E. , Haycock John , Allwood Dan A.
Published: May 2010

Domain walls may act as localized field sources to trap and move superparamagnetic beads for manipulating biological cells and DNA. The interaction between beads of various diameters and a wall is investigated using a combination of micromagnetic and analytical models. Domain walls can transport beads under applied magnetic fields but the mutual attraction between the bead and wall causes drag forces affecting the bead to couple into the wall motion. Therefore, the interaction with the bead causes a fundamental change in the domain wall dynamics, reducing the wall mobility by five orders of magnitude.
Effects of early weaning on growth, feed efficiency and carcass traits in Shorthorn cattle
Authors: Wolcott M. L. , Graser H.-U. , Johnston D. J.
Published: May 2010

This study aimed to examine the impact of early weaning on residual feed intake, and other production and carcass traits, in a group of cattle subjected to early or conventional weaning treatments, but otherwise managed as contemporaries. Shorthorn (n = 140) calves were randomly allocated by sex and sire to early and conventional weaning treatments. Early weaned animals (n = 69) were weaned at an average of 123 days of age and 145 kg liveweight, while conventionally weaned steers and heifers (n = 71) were 259 days old at weaning and 273 kg. Following conventional weaning, animals were managed as contemporaries through backgrounding, and entered feedlot finishing at a mean age of 353 and 408 days for heifers and steers, respectively, for finishing and feed intake testing. At the conclusion of feed intake testing hip height was measured, and animals were ultrasound scanned to assess fat depth, eye muscle area and percent intramuscular fat. Early weaned animals were significantly lighter (P < 0.001) than their conventionally weaned contemporaries, when weighed at conventional weaning. The weight difference observed at conventional weaning of 19.4 kg between treatment groups persisted throughout the experiment, with significant (P < 0.05) differences of 17.1, 15.6 and 15.8 kg at feedlot entry, and the start and end of the feed intake test period, respectively. Weaning treatment also approached significance for daily feed intake (P = 0.06), with early weaned animals tending to eat less than their conventionally weaned contemporaries (daily feed intake = 11.6 and 12.0 kg, respectively). Weaning treat\ment did not significantly affect feed efficiency whether measured as residual feed intake (P = 0.64) or feed conversion ratio (P = 0.27). None of the other traits measured were significantly affected by weaning treatment. These data showed that early weaning, as implemented for this experiment, resulted in animals that were lighter than their conventionally weaned contemporaries through backgrounding and finishing. Weaning treatment did not, however, influence feed efficiency or the post-weaning growth and carcass composition traits measured for this experiment.
Crown Rot of Bananas: Preharvest Factors Involved in Postharvest Disease Development and Integrated Control Methods
Authors: Lassois Ludivine , Jijakli M. Haïssam , Chillet Marc , de Lapeyre de Bellaire Luc
Published: May 2010

Crown rot is a complex disease that affects export bananas in all banana-producing countries. Usually invisible when the fruits are packed for transportation from tropical countries to distant destinations, disease symptoms occur during shipment, ripening, and storage. This disease, characterized by rot and necrosis, affects tissues joining the fingers with each other, called the crown. It may reach the pedicel and even the banana pulp when crown rot is severe. Losses from 10 to 86% have been recorded for treated and untreated bananas, respectively. In this paper, we summarize the current knowledge on crown rot disease and associated control measures that must be considered throughout the production channel in order to be effective. We suggest a new approach to this postharvest disease of bananas: that of considering fruit quality potential in the field. This new concept of preharvest quality potential is a key factor to understanding crown rot development. Fruit quality potential depends on both a physiological and a parasitic component, both of which depend on agrotechnic and pedoclimatic factors of the crop production area. The physiological component is defined as the sensitivity of the fruits to crown rot, and the parasitic component reflects the capacity of the parasitic complex to induce a level of disease. The content of this review is divided into two parts. First, the fruit quality potential at field level is addressed, with special emphasis on its physiological and parasitic components. Second, the control methods are examined at different steps of the channel, in order to give an overview of a possible integrated control strategy.
Occurrence and Molecular Identification of Azoxystrobin-Resistant Colletotrichum cereale Isolates from Golf Course Putting Greens in the Southern United States
Authors: Young Joseph R. , Tomaso-Peterson Maria , Tredway Lane P. , de la Cerda Karla
Published: May 2010

Turfgrass anthracnose, caused by Colletotrichum cereale (≡C. graminicola), has become a common disease of creeping bentgrass and annual bluegrass putting greens throughout the southern United States. Strobilurin (QoI) fungicides such as azoxystrobin are single-site mode-of-action fungicides applied to control C. cereale. In vitro bioassays with azoxystrobin at 0.031 and 8 μg/ml incorporated into agar were performed to evaluate the sensitivity of 175 isolates collected from symptomatic turfgrasses in Alabama, Mississippi, North Carolina, Tennessee, and Virginia. Three sensitivity levels were identified among C. cereale isolates. Resistant, intermediately resistant, and sensitive isolates were characterized by percent relative growth based on the controls with means of 81, 23, and 4%, respectively, on media containing azoxystrobin at 8 μg/ml. The molecular mechanism of resistance was determined by comparing amino acid sequences of the cytochrome b protein. Compared with sensitive isolates, C. cereale isolates exhibiting QoI resistance had a G143A substitution, whereas isolates expressing intermediate resistance had a F129L substitution. C. cereale isolates displaying azoxystrobin resistance in vitro were not controlled by QoI fungicides in a field evaluation. The dominance of QoI-resistant C. cereale isolates identified in this study indicates a shift to resistant populations on highly managed golf course putting greens.