bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature and pressure dependence of the recombination mechanisms in 1.3 μm and 1.5 μm GaInNAs lasers
Authors: McConville Daniel G. , Sweeney Stephen J. , Adams Alfred R. , Tomic Stanko , Riechert Henning 
Published: December 2006

AbstractWe have studied the pressure and temperature dependence of the threshold current density, J th, in 1.3 μm and 1.5 μm GaInNAs edge‐emitting lasers. We find that J th is more temperature sensitive for the 1.5 μm devices. From analysis of the spontaneous emission from these devices we find that J th for the 1.3 μm devices is comprised of 50% non‐radiative monomolecular recombination, 25% radiative recombination and 25% non‐radiative Auger recombination at room temperature. In the 1.5 μm devices however it is composed of 30% monomolecular recombination, 10% radiative recombination and 60% Auger recombination. It is clear that the major difference in J th between the devices is caused by the increased Auger recombination in the 1.5 μm devices. Previously, we found that J th for 1.3 µm GaInNAs lasers increases with pressure due to the increase in Auger recombination brought about by a large increase in the cubed threshold carrier density (n 3th). However, for the 1.5 µm devices, we find no significant change in J th with pressures up to 8 kbar. We suggest that this is due to the higher Auger coefficient for the 1.5 µm devices, which compensates for the increase in n 3th with pressure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrational properties of single walled carbon nanotubes under pressure from Raman scattering experiments and molecular dynamics simulations
Authors: Choi In‐Hwan , Yu Peter Y. , Tangney Paul , Louie Steven G. 
Published: December 2006

AbstractWe have investigated theoretically and experimentally the pressure dependent structural and vibrational properties of single‐walled carbon nanotubes (SWNT). Bundles of SWNTs are studied inside a diamond anvil high pressure cell with micro‐Raman scattering. The tube diameter and size distribution are determined from the radial breathing modes (RBM) of the tubes. The pressure coefficient and linewidth of one of the high frequency C–C bond stretching modes was found to change suddenly at ∼3 GPa which is well below the structural transformation pressure (P c) for the tubes in our sample. Molecular dynamics simulations were used to calculate the vibrational density of states of SWNTs as a function of pressure. Our simulations suggest that the experimental results can be explained by a softening of a low‐frequency optical mode of the SWNTs – the “squashing” mode – and the dynamical effect of this softening on other phonon modes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calibration of the ruby pressure scale to 150 GPa
Authors: Silvera Isaac F. , Chijioke Akobuije D. , Nellis W. J. , Soldatov A. , Tempere J. 
Published: December 2006

AbstractFor many years the ruby pressure standard has been the so‐called quasi‐hydrostatic scale of Mao, Xu, and Bell published in 1986. The calibration was determined by X‐ray diffraction of metal markers in an argon pressurization medium to 80 GPa, along with simultaneous measurement of the shift of the ruby R lines. We have used data in the literature, as well as our own, mostly for ruby in quasi‐hydrostatic helium, to produce a new ruby scale with calibration data that extends to 150 GPa. The new scale shows that at the highest shifts of the ruby R lines the pressures are substantially higher than on the old scale. To understand small systematic shifts of the pressures as determined from the X‐ray diffraction of metal “markers” used in the calibration, a finite element analysis of quasi‐hydrostatic conditions in a diamond anvil cell has been carried out. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
It's time to celebrate!
Authors: Stutzmann Martin 
Published: December 2006

AbstractThe beginning of the 19th century was a remarkable period for culture and science, indeed. Many of Beethoven's great works were performed for the first time, the first asteroids Ceres and Pallas were discovered, Alessandro Volta informed the Royal Society in London about a new source for electrical current, the industrial revolution began with the invention of punch card controlled weaving machines by Jacquard and the appearance of steam engines as power sources for ships or trains, and Alexander von Humboldt travelled and surveyed the New World. At the same time, also the foundations of modern crystallography and solid state science were laid, with the discovery of many metallic elements and, most notably, the first editions of René Just Haüy's “Traité de Minéralogie” in 1801 and the “Traité de Physique” in 1803.On this scale of events, the opening of a small printing shop in lower Manhattan by Charles Wiley in 1807 remained practically unnoticed. However, in the following 200 years not only did solid state physics develop into one of the most active fields in modern science, but also the small printing shop did prosper into one of the largest science publishers worldwide. physica status solidi became part of the Wiley family with the acquisition of VCH in 1996 and, since then, has enjoyed the support and stimulating atmosphere as the largest solid state physics unit within Wiley. Thus, all members of the Editorial Office and all Editors of physica status solidi take great pleasure in congratulating Wiley on the occasion of the 2007 Bicentennial and expressing their best wishes for a prosperous future!Also physica status solidi has continued its growth and positive development under the publishing agreement entered with Wiley in 2002. Thus, the number of submitted and published articles has again increased significantly in the past year, by 20% and 25%, respectively. Among the other notable events in 2006 was the completion of the Physics and Astronomy Backfile Collection, which now provides easy and complete access to more than 300 000 pages published in physica status solidi since the foundation of the journal at www.interscience.wiley.com/backfiles/physics. And last but not least, the Rapid Research Letter section of physica status solidi has just been launched as an independent journal, pss‐RRL, complementing pss (a), pss (b), and pss (c) by providing a special service for the fast publication of important new findings in all areas of solid state physics. Please have a look at the home page of the new journal www.pss‐rapid.com for further details.As this year comes to an end, I would like to express my sincere thanks to our authors, referees, readers, and everybody involved in editing and producing physica status solidi for their continued interest, valuable contributions, and dedication. Good luck and all the best for 2007! And once again: Happy 200th anniversary, Wiley!Garching, December 2006
The response of the coupled tropical ocean–atmosphere to westerly wind bursts
Authors: Fedorov Alexey V. 
Published: December 2006

AbstractTwo different perspectives on El Niño are dominant in the literature: it is viewed either as one phase of a continual southern oscillation (SO), or alternatively as the transient response to the sudden onset of westerly wind bursts (WWBs). Occasionally those bursts do indeed have a substantial effect on the SO—the unusual strength of El Niño of 1997/98 appears to be related to a sequence of bursts—but frequently the bursts have little or no impact. What processes cause some bursts to be important, while others remain insignificant? The question is addressed by using a simple coupled tropical ocean–atmosphere model that simulates a continual, possibly attenuating, oscillation to study the response to WWBs. The results show that the impact of WWBs depends crucially on two factors: (i) the background state of the system as described by the mean depth of the thermocline and intensity of the mean winds, and (ii) the timing of the bursts with respect to the phase of the SO. Changes in the background conditions alter the sensitivity of the system, so that the impact of the bursts on El Niño may be larger during some decades than others. Changes in the timing of WWBs affect the magnitude and other characteristics of the SO by modifying the energetics of the ocean–atmosphere interactions. A reasonable analogy is a swinging pendulum subject to modest blows at random times—those blows can either magnify or diminish the amplitude, depending on their timing. It is demonstrated that a WWB can increase the strength of El Niño significantly, if it occurs 6 to 10 months before the peak of warming, or can reduce the intensity of the subsequent El Niño, if it occurs during the cold phase of the continual SO. Copyright © 2002 Royal Meteorological Society.
The dynamically driven long‐term trend in stratospheric ozone over northern middle latitudes
Authors: Hadjinicolaou Panos , Jrrar Amna , Pyle John A. , Bishop Lane 
Published: December 2006

AbstractThe cause of the observed mid‐latitude decline in ozone in a 20‐year integration of a stratospheric chemical transport model forced by European Centre for Medium‐Range Weather Forecasts analyses for the years 1979 to 1998 is investigated. A very simple chemical scheme for ozone is used which includes no interannual variation so that any modelled interannual variability, or trend, must arise from changes in the meteorology. The integration from 1979 to 1998 does show a downward trend in mid‐latitude ozone in which many of the observed features are reproduced, especially between the middle 1980s and the early 1990s. A detailed statistical trend analysis shows that the quantitative comparison between modelled and observed trend is very sensitive to the choice of period considered. However, there is good qualitative agreement in terms of the latitudinal variation of the trend. For the different periods considered, the dynamically driven model trend accounts for at least half of the observed northern mid‐latitude trend averaged over December to February. The vertical variation of the modelled and observed trends agree qualitatively. The modelled total ozone correlates well with the vertical winter EP‐flux at 100 hPa and the North Atlantic Oscillation index, suggesting that long‐term changes in stratospheric circulation are intimately connected to the observed mid‐latitude ozone trend. Copyright © 2002 Royal Meteorological Society.
Nucleation effects on the habit of vapour grown ice crystals from −18 to −42°C
Authors: Bailey M. , Hallett J. 
Published: December 2006

AbstractIce crystals have been nucleated and grown by a new method where supersaturation is controlled by combining static diffusion chamber and expansion chamber techniques. Crystals were nucleated and grown on $50\ \mu \hbox{m}$ diameter glass filaments at pressures of 500 to 300 hPa, typical of clouds with temperatures from −18 to −42°C, respectively. Crystals were also nucleated on particles of finely powdered silver iodide and kaolinite adhering to glass filaments, in order to investigate effects on habit due to different nucleating materials. Critical supersaturations for nucleation were measured for each case and were in good agreement with previous nucleation studies. Crystals were grown at ice supersaturations which ranged from less than 1% to just above water saturation. For ice growth below a critical supersaturation, nucleation was achieved by applying a brief adiabatic expansion to the static diffusion chamber with a filament in place and the chamber evacuated to the target pressure for the temperature of interest. Nucleation occurred at a critical supersaturation, followed by growth at a lower value. A review of past laboratory experiments and recent in situ observations reveals good agreement between laboratory and field observations when the effects of nucleating methods and growth times are taken into account. Contrary to studies which report the habit of ice as ‘prism’‐like or columnar below approximately −22°C, the habit is found to be plate‐like for temperatures ranging from −18°C to −40°C at ice supersaturations relevant to the atmosphere. Additionally, the plate‐like‐habit distribution is dominated by polycrystalline forms, which is consistent with aspects of past laboratory studies and recent observations obtained with improved aircraft instrumentation. The habits and habit distributions obtained from glass and kaolinite most closely resemble those observed in the atmosphere, while the results from silver iodide show large differences. Below −40°C, the habit becomes columnar except at low supersaturation, and is still dominated by polycrystals which appear as rosettes for ice supersaturations greater than about 20%. ‘Bullet rosettes’ were observed to nucleate and grow on clean glass threads below −40°C but not on kaolinite which predominantly grew single columns and irregular polycrystals with columnar components; silver iodide produced single columns with few polycrystals. This behaviour indicates that rosettes result from ice nuclei which share few or no crystallographic similarities with ice, and is consistent with that expected from homogeneous nucleation. Critical supersaturation measurements for nucleation were extended down to −70°C, and revealed that below −40°C ice crystals can nucleate on glass at ice supersaturations of 25%, and at values of approximately 15% on kaolinite or silver iodide. Copyright © 2002 Royal Meteorological Society
Insights into cloud parametrization provided by a prognostic approach
Authors: Gregory David , Wilson Damian , Bushell Andrew 
Published: December 2006

AbstractStarting from an assumption that within an area there is a distribution of temperature and humidity, equations are derived for the prognostic evolution of cloud fraction and area‐mean condensed water under the action of uniform forcing. These are contrasted to alternative equation sets which are based upon consideration of humidity variations alone, and approximations involved in the derivations of these are highlighted. The properties of, and relationships between, current diagnostic and prognostic cloud schemes are examined using the prognostic formulation, and assumptions concerning the nature of the subgrid distribution of thermodynamic variables are discussed. While the approaches of Smith and Tiedtke provide a consistent description of cloud formation, the Sundqvist approach is found to implicitly include changes in the character of the distribution as cloud cover increases, inconsistent with an assumption of uniform forcing. Additional properties of the Tiedtke scheme are explored and extensions suggested to improve the treatment of cloud dissipation. © Crown Copyright 2002.
The axial coherence of Kelvin–Helmholtz billows
Authors: Thorpe S. A. 
Published: December 2006

AbstractFactors affecting the along‐axis coherence length of Kelvin–Helmholtz billows are reviewed. Little is known of the processes which determine or limit this length. Laboratory experiments show that, as they develop, billows may be irregularly spaced, resulting in pairing along their length, or, more commonly, grow at different rates in patches which subsequently amalgamate. Both processes result in features described as ‘knots’, where neighbouring billows join. The tangling of billow vortices in the knots leads to local turbulence and mixing, often before turbulence develops at a smaller scale within the billows themselves. The axial coherence length of billows is limited to the along‐axis distance between these knots. Such features in the atmosphere and the ocean have received little attention in spite of their possible bearing on clear‐air turbulence and to heat and momentum transport. Observations of atmospheric billows suggest an axial coherence length which is of the same order as that found in the laboratory, about four billow wavelengths. Copyright © 2002 Royal Meteorological Society.
Gravity waves generated by the dry convective boundary layer: Two‐dimensional scale selection and boundary‐layer feedback
Authors: Lane. Todd P. , Clark Terry L. 
Published: December 2006

AbstractThis study examines the generation of gravity waves by the dry convective boundary layer in two dimensions. In particular, a number of cases are considered which range from zero background‐flow conditions to conditions with strong wind shear. These experiments agree with previous studies that identified a distinct horizontal‐scale selection of the gravity waves due to changes in wind speed. Detailed linear analysis is completed which attributes the horizontal‐scale selection to two processes. The first process is the dissipation of downstream‐propagating gravity waves by critical levels, and the second process is the trapping of upstream‐propagating waves. The result is a narrow region of the generated spectrum of gravity waves that are able to propagate vertically. The experiments also agree with previous studies that have observed a resonant interaction between the boundary‐layer thermals and the gravity waves. This resonance is described as a result of the trapped gravity waves, which form a resonant cavity near the top of the mixed layer. Finally, the experiments are used to evaluate the role of shear in the gravitywave generation. In cases with little resonance, shear is shown to play a minor role in the wave generation. In these cases, changes in the wave's amplitude spectrum are mostly due to linear wave refraction and the aforementioned selection mechanism. Copyright © 2002 Royal Meteorological Society.
The role of advection of fluxes in modelling dispersion in convective boundary layers
Authors: Abiodun Babatunde J. , Enger Leif 
Published: December 2006

AbstractA Eulerian three‐dimensional higher‐order closure dispersion model is presented. The model uses mean wind and turbulence quantities from a second‐order atmospheric boundary‐layer model. The dispersion model is validated against results from tank and field experiments and compared to results from Lagrangian dispersion models. The results show quite good agreement with experiment and Lagrangian modelling results for point source dispersion in a convective boundary layer (CBL). Sensitivity studies with the model help to identify the role played by advection and horizontal transport terms in the equations for the fluxes in simulating the essential features of pollutant dispersion.Results from the sensitivity tests show that the characteristic features of dispersion from point sources in the CBL—with an ascending plume during ground‐level release and a descending plume from a lifted point source—are caused by an imbalance between the advection and diffusion terms in the equation for the vertical flux. Furthermore, it is shown that there is also a tendency for the plume to split horizontally, which is similarly caused by an imbalance between the advection and diffusion terms in horizontal fluxes. The simulated lateral standard deviations of distance x from a point source, for the vertically integrated concentration, are proportional to x close to the source and to x1/2 far away from the source, if and only if the advection and diffusion terms are included in the equations for the turbulent fluxes of concentration. Copyright © 2002 Royal Meteorological Society.
The impact of time‐averaging on the detectability of nonlinear empirical relations
Authors: Yuval  , Hsieh William W. 
Published: December 2006

AbstractThis paper studies how time‐averaging of observations can affect the detectable nonlinear empirical relations in the data. The example used is the simulation of the precipitation rate as a daily, weekly and monthly variable. The feedforward neural network (NN) model is employed to simulate the precipitation rate. A measure of the nonlinearity of the NN relation is introduced and is used to calculate the nonlinearity of the NNs. It is found that the use of data averaged over periods longer than the inherent time‐scale of the involved variables can result in a dramatic weakening of the detected nonlinearity. A suggested theoretical explanation asserts that averaging of independent samples of the data records yields distributions approaching the multi‐variate normal, in which case the relations among the variables are closer to linear. Copyright © 2002 Royal Meteorological Society.
Diagnosis of systematic forecast errors dependent on flow pattern
Authors: Ferranti L. , Klinker E. , Hollingsworth A. , Hoskins B. J. 
Published: December 2006

AbstractSingular‐value decomposition (SVD) analysis is employed to study flow‐dependent forecast errors. The results presented are based on ECMWF operational forecasts and verifying analysis of 500 hPa heights for the most recent seven winter periods. Beyond forecast day 3 the flow‐dependent errors are mainly localized over the Atlantic sector and are associated with the North Atlantic Oscillation‐ (NAO)‐like circulation anomalies. The forecasts systematically underestimate the intensity of pressure anomalies centred over Iceland with the effect of reducing the anomalous westerly/easterly flow over the eastern north Atlantic/western Europe. The flowdependent component of the errors explains about 10% of the total forecast‐error variance. However, since it is associated with the NAO mode that dominates the variability of the European weather on longer time‐scales, it is essential to identify the model limitations in predicting this flow anomaly in order to guide future work on improving forecasts over Europe.The relationship between forecast‐error variability and NAO fluctuations is effectively described by an SVD analysis performed on fields of forecast‐error magnitude and analyses. Regions with large (small) forecast‐error anomalies are located over the maximum of the anomalous westerly (easterly) jet, while on the flanks of the jet the error anomaly is expected to be minimum/maximum. Copyright © 2002 Royal Meteorological Society.
The development and testing of a new two‐time‐level semi‐Lagrangian scheme (SETTLS) in the ECMWF forecast model
Authors: Hortal Mariano 
Published: December 2006

AbstractA new treatment of the two‐time‐level semi‐Lagrangian scheme is presented which avoids extrapolation in time of the velocities used for the computation of the trajectories and for the nonlinear terms of the evolution equations.Extrapolation in time is used in the original two‐time‐level scheme in order to make it centred in time and therefore second‐order accurate. This time‐extrapolation can lead to instabilities. In the new scheme the secondorder accuracy is achieved by means of a Taylor series expansion to second order around the departure point of the semi‐Lagrangian trajectory thus avoiding extrapolation of the first‐order term. The estimate of the secondorder term in this expansion is obtained by means of a stable time extrapolation from the previous time step and therefore the scheme is named the ‘Stable Extrapolation Two‐Time‐Level Scheme’ or SETTLS.Some cases of noise in forecast fields, arising from an instability of the time extrapolation in the version of the two‐time‐level semi‐Lagrangian scheme used operationally at the European Centre for Medium‐Range Weather Forecasts (ECMWF) between December 1996 and April 1998, are diagnosed; it is shown that the noise can be removed by the use of the SETTLS. Copyright © 2002 Royal Meteorological Society.