bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoluminescence depth‐profiling of lattice‐mismatched InGaN thick film on GaN using inductively coupled plasma etching
Authors: Lee Ji‐Myon , Kim Byung‐Il , Park Seong‐Ju 
Published: May 2006

AbstractPhotoluminescence depth profiling of highly strained In0.1Ga0.9N and In0.15Ga0.85N epitaxial films have been studied employing an inductively coupled Cl2 plasma etching. The photoluminescence measurements showed that thick InGaN films (0.2 μm) consist of three different structural phases; (i) an InN‐rich region near the InGaN film surface, (ii) a region that was free from InN‐rich phase under stress‐relaxation in the middle of the film, and (iii) an InGaN/GaN interface region. In region (i), a higher wavelength peak from the InN‐rich phase was dominant. After removing the surface layer of 500 Å, the PL peaks from InN‐rich phases completely disappeared, suggesting that the InN‐rich phase region is confined to a depth of 500 Å. In regions of (ii) and (iii), the strain‐relaxation between InGaN and GaN had a significant influence on the luminescence properties of InGaN. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
General solution for complete plane strain problem of a nonhomogeneous body with a doubly‐periodic set of inlays
Authors: Li X. 
Published: May 2006

AbstractIn this paper, we study the complete plane strain problem of a nonhomogeneous body with a doubly‐periodic set of cylindrical inlay by using the complex potential method, which is one of the most promising and efficient methods and has become a classic but not lost its significance even today, and obtain the general solution in closed form. For an illustrating example, e.g. the doubly‐periodic circular cylindrical inlay problem, the exact solution is obtained. When we fix one of its periods, say o1 = aπ and let |o2| → ∞ in such a way that $Im({\omega_2\over \omega_1})$> 0, Im (o1) = 0, we get the exact solution of the singly‐periodic case with the primitive period a π, this solution is identical with the known solution, furthermore, when we let |o1|→ ∞ and |o2| → ∞ in the doubly‐periodic case, or a → ∞ in the singly‐periodic case, we have immediately the exact solution of the non‐periodic case.
An analytical solution of incompressible charged porous media
Authors: Malakpoor K. , Kaasschieter E.F. , Huyghe J.M. 
Published: May 2006

AbstractA one‐dimensional analytical solution is derived for free swelling and consolidation of a saturated charged porous medium. The derived equations describe infinitesimal deformation of charged porous media saturated with a fluid with dissolved cations and anions. In the one‐dimensional case the governing equations reduce to a coupled diffusion equations for electro‐chemical potentials. Suitable initial and boundary conditions based on consolidation or free swelling experiments complete the equations.
Defining patch contribution in source‐sink metapopulations: the importance of including dispersal and its relevance to marine systems
Authors: Figueira Will F. , Crowder Larry B. 
Published: May 2006

AbstractIn metapopulations, individual patch contribution (source or sink) is typically calculated as a patch growth rate (the “intrinsic” lambda,λI) dependent only upon local demographics. We demonstrate that when dispersal is explicitly included in the model, the growth rates for all patches calculated in an analogous manner (the “observed” lambda,λO) equilibrate to the overall metapopulation growth rate and thus no longer serve as a useful reflection of the demographic and dispersive characteristics of a given patch. In these situations we suggest an alternative method of estimating patch contribution (the “contribution” lambda,λC) in which a patch is decremented for losses that occur within it and credited for gains that occur anywhere in the metapopulation because of it. We compare values ofλI,λO, andλCfor individual patches in discrete‐time density‐independent metapopulation models of two organisms with very different life histories, mayflies with adult dispersal, and reef fish with larval dispersal. Results confirm that when dispersal is included onlyλCclearly indicates the contribution of a particular patch.λI−λCcomparisons indicate that inclusion of dispersal in the mayfly model was only important if connectivity patterns were random or directional. In the reef fish model, however, results were very different when dispersal was included and there were many cases of patches being misidentified (e.g., as a source when it was really a sink) depending upon the metric used (λIorλC). Our results demonstrate the importance of including dispersal in metapopulation models when considering the contribution of individual patches.
Consequences of youth tobacco use: a review of prospective behavioural studies
Authors: Mathers M. , Toumbourou J. W. , Catalano R. F. , Williams J. , Patton G. C. 
Published: May 2006

ABSTRACTBackground  Cigarette smoking represents a significant health problem and tobacco has been identified as causing more preventable diseases and premature deaths than any other drug. Although health consequences from smoking have been documented, there has been a surprising lack of research into behavioural consequences.Aims  To review what is known of the long‐term relationship between patterns of tobacco use prior to age 18 years and behavioural consequences in adulthood.Method  A literature search of electronic abstraction services from 1980 to September 2005 was conducted. To be included in the review, studies had to have large, representative samples, be longitudinal studies with baseline age under 18 years and follow‐up age 18 years or older and clarify effects due to attrition, leaving 16 articles that met the inclusion criteria. Two reviewers evaluated each paper.Findings  Adolescent tobacco use predicts a range of early adult social and health problems. Surprisingly few studies met the inclusion criteria. The limited evidence available suggests that adolescent tobacco smoking increases the likelihood of early adult tobacco use and the initiation of alcohol use or the development of alcohol‐related problems. The link between adolescent tobacco use and subsequent cannabis use was not resolved convincingly from the studies summarized. The effects of tobacco use on later illicit drug use tended to fall away when adjusting for underlying risk factors. Existing studies of the effects of tobacco use on later mental health have many limitations. Nevertheless, a finding that youth tobacco use may predict subsequent mental health problems deserves further investigation. The possible effects of tobacco use on academic/social problems and sleep problems also warrant further investigation.Conclusion  This review highlights links between youth tobacco use and subsequent behavioural and mental health problems. It provides health care professionals with evidence of the possible harmful effects of youth tobacco smoking on later social, emotional, and behavioural well‐being.
Non‐lethal effect of the invasive predator Bythotrephes longimanus on Daphnia mendotae
Authors: PANGLE KEVIN L. , PEACOR SCOTT D. 
Published: May 2006

Summary1. We evaluated the antipredator behaviour of Daphnia mendotae to the invasive invertebrate predator, Bythotrephes longimanus, and the consequent effect of the predator on prey growth rate (referred to as a non‐lethal effect of the predator).2. In a laboratory experiment, Daphnia in the absence of Bythotrephes kairomones remained in the top, warmer regions of experimental columns, whereas in the presence of Bythotrephes kairomones, Daphnia migrated vertically, occupying a middle region by night and a low, cold region during the day. Over a 4‐day experiment, the vertical migration induced by Bythotrephes caused a 36% reduction in the somatic growth rate of Daphnia, a level that is sufficient to have an effect on prey population growth rate.3. A second laboratory experiment indicated that concentrations of Bythotrephes kairomones in water taken directly from the field (Lake Michigan) were high enough to induce behavioural shifts that led to these large reductions in somatic growth rate.4. Our results identify a means by which Bythotrephes has substantial effects on native prey populations other than through direct consumption.
Energy crops: current status and future prospects
Authors: SIMS RALPH E. H. , HASTINGS ASTLEY , SCHLAMADINGER BERNHARD , TAYLOR GAIL , SMITH PETE 
Published: May 2006

AbstractEnergy crops currently contribute a relatively small proportion to the total energy produced from biomass each year, but the proportion is set to grow over the next few decades. This paper reviews the current status of energy crops and their conversion technologies, assesses their potential to contribute to global energy demand and climate mitigation over the next few decades, and examines the future prospects. Previous estimates have suggested a technical potential for energy crops of∼400 EJ yr−1 by 2050. In a new analysis based on energy crop areas for each of the IPCC SRES scenarios in 2025 (as projected by the IMAGE 2.2 integrated assessment model), more conservative dry matter and energy yield estimates and an assessment of the impact on non‐CO2 greenhouse gases were used to estimate the realistically achievable potential for energy crops by 2025 to be between 2 and 22 EJ yr−1, which will offset∼100–2070 Mt CO2‐eq. yr−1. These results suggest that additional production of energy crops alone is not sufficient to reduce emissions to meet a 550 μmol mol−1 atmospheric CO2 stabilization trajectory, but is sufficient to form an important component in a portfolio of climate mitigation measures, as well as to provide a significant sustainable energy resource to displace fossil fuel resources. Realizing the potential of energy crops will necessitate optimizing the dry matter and energy yield of these crops per area of land through the latest biotechnological routes, with or without the need for genetic modification. In future, the co‐benefits of bioenergy production will need to be optimized and methods will need to be developed to extract and refine high‐value products from the feedstock before it is used for energy production.
Carbon isotope composition of fossil charcoal reveals aridity changes in the NW Mediterranean Basin
Authors: FERRIO J. P. , ALONSO N. , LÓPEZ J. B. , ARAUS J. L. , VOLTAS J. 
Published: May 2006

AbstractAlthough several proxies for the inference of precipitation have been proposed, evidence of changes in aridity during the Holocene is scarce, and most is only qualitative. Moreover, precipitation regimes show relatively poor spatial correlations and can exhibit contrasting responses to global climate trends in different areas. Thus, there is a need to concentrate efforts at the local scale in order to increase the spatial resolution of palaeoclimate records, especially regarding water availability in semiarid zones. We propose the analysis of carbon isotope composition (δ13C) in fossil charcoal (routinely recovered from archaeological sites) to quantify changes in water availability in the past. We applied this approach to reconstruct variations in aridity during the last four millennia in the Ebro Depression (NE Iberian Peninsula). First, we studied the effect of carbonization over a range of temperatures (300–500°C) on the δ13C of Aleppo pine (Pinus halepensis Mill.) wood cores, collected from nine locations in NE Iberian Peninsula with distinct water availability. Despite significant changes in δ13C caused by carbonization, the original climatic signal of wood δ13C was well preserved. Moreover, δ13C shifts induced by this process were successfully corrected by accounting for variation in charcoal carbon concentration (%C). After removing the effect of carbonization, we estimated annual precipitation (P) and the ratio between annual precipitation and evapotranspiration (P/E) from the δ13C of fossil charcoal. In general, estimated water availability in the past was higher than present values, indicating that latter‐day (semiarid) conditions are mostly due to recent climate changes. The good agreement between our findings and other evidence indicates that the analysis of δ13C in charcoal may be useful to expand current palaeoclimate records as it provides a complementary (and quantitative) source of information to assess climate dynamics.
A psychometric evaluation of the Learning Styles Questionnaire: 40‐item version
Authors: Klein Britt , McCall Louise , Austin David , Piterman Leon 
Published: May 2006

AbstractSixty‐six English‐speaking postgraduate distance‐education medical students completed the Learning Styles Questionnaire (LSQ: 40‐item version). This was completed while attending a residential workshop at the beginning of the semester, and 44 of these students completed the same LSQ questionnaire 5 months later at the completion of the semester. The psychometric properties of the LSQ were assessed using Cronbach’s alpha (internal consistency), test‐retest, correlational analyses and factor analysis. The results indicated that the LSQ (40‐item version) has poor reliability and validity, and therefore requires further development and psychometric evaluation.
A Cautionary Note on Estimating the Standard Error of the Gini Index of Inequality*
Authors: Modarres Reza , Gastwirth Joseph L. 
Published: May 2006

AbstractWe will show that the regression approach to estimating the standard error of the Gini index can produce incorrect results as it does not account for the correlations introduced in the error terms once the data are ordered. To assess the effect of ignoring the correlation in the error terms we examined two distributions and show that the regression method overestimates the standard error of the Gini index. We recommend that the more mathematically complex or computationally intensive methods be used.
Discovery of magnetic fields in the βCephei star ξ1 CMa and in several slowly pulsating B stars
Authors: Hubrig S. , Briquet M. , Schöller M. , De Cat P. , Mathys G. , Aerts C. 
Published: May 2006

Abstract
We present the results of a magnetic survey of a sample of eight β Cephei stars and 26 slowly pulsating B (SPBs) stars with the FOcal Reducer low dispersion Spectrograph at the Very Large Telescope. A weak mean longitudinal magnetic field of the order of a few hundred Gauss is detected in the β Cephei star ξ1CMa and in 13 SPB stars. The star ξ1CMa becomes the third magnetic star among the β Cephei stars. Before our study, the star ζ Cas was the only known magnetic SPB star. All magnetic SPB stars for which we gathered several magnetic field measurements show a field that varies in time. We do not find a relation between the evolution of the magnetic field with stellar age in our small sample. Our observations imply that β Cephei and SPB stars can no longer be considered as classes of non-magnetic pulsators, but the effect of the fields on the oscillation properties remains to be studied.
Intracellular Hydrogen Peroxide Production Is an Upstream Event in Apoptosis Induced by Down-Regulation of Casein Kinase 2 in Prostate Cancer Cells
Authors: Ahmad Kashif A. , Wang Guixia , Ahmed Khalil 
Published: May 2006

AbstractWe have shown previously that down-regulation of CK2 activity (protein kinase CK2, formerly casein kinase 2) by employing its inhibitors apigenin or 4,5,6,7-tetrabromobenzotriazole promotes apoptosis in prostatic carcinoma cells. In an effort to define the downstream mediators of this action, we show that cell apoptosis observed on down-regulation of CK2 is preceded by intracellular generation of hydrogen hydroxide (H2O2) in various normal and cancer cells. In this regard, both androgen-dependent ALVA-41 and androgen-independent PC-3 cells treated with 80 μmol/L apigenin or 4,5,6,7-tetrabromobenzotriazole or with antisense CK2α oligonucleotide or small interfering RNA respond similarly to down-regulation of CK2. Interestingly, whereas chemical inhibitors of CK2 elicited H2O2 production in both cancer and noncancer cells, the antisense CK2α-mediated down-regulation of CK2 showed significant H2O2 production in cancer cells but had minimal effect in noncancer cells. The basis of this key difference is unclear at present, but this observation may have implications for the therapeutic potential of antisense CK2 oligonucleotide in cancer therapy. The H2O2 production induced by antisense CK2α was associated with robust caspase-3 activity, nuclear factor-κB nuclear translocation, cytochrome c release, and subsequent DNA fragmentation in prostate cancer cells (ALVA-41 and PC-3). These findings describe, for the first time, a relationship between CK2 and reactive oxygen species, such that CK2 inhibition leads to production of intracellular H2O2, which may serve as a downstream mediator of apoptosis in cancer cells. (Mol Cancer Res 2006;4(5):331–8)
Snow Cover Distribution, Variability, and Response to Climate Change in Western China
Authors: Dahe Qin , Shiyin Liu , Peiji Li 
Published: May 2006

Abstract
A study is presented of the geographical distribution and spatial and temporal variabilities of the western China snow cover in the past 47 yr between 1951 and 1997. The data used consist of Scanning Multichannel Microwave Radiometer (SMMR) 6-day snow-depth charts, NOAA weekly snow extent charts, and the daily snow depth and number of snow cover days from 106 selected meteorological stations across western China. Empirical orthogonal function was performed on the SMMR dataset to better understand the spatial pattern and variability of the Qinghai–Xizang (Tibet) snow cover. A multiple linear regression analysis was conducted to show the association of interannual variations between snow cover and snow season temperature as well as precipitation. Further, the autoregressive moving average model was fitted to the snow and climate time series to test for their long-term trends. Results show that western China did not experience a continual decrease in snow cover during the great warming period of the 1980s and 1990s. It is of interest to note that no correlation was identified between temperature and precipitation in the snow cover season. However, year-to-year fluctuation of snow cover responds to both snowfall and snow season temperature. About one-half to two-thirds of the total variance in snow cover is explained by the linear variations of snowfall and snow season temperature. The long-term variability of western China snow cover is characterized by a large interannual variation superimposed on a small increase trend. The positive trend of the western China snow cover is consistent with increasing snowfall, but is in contradiction to regional warming. In addition, many constraints of the Qinghai–Xizang (Tibet) snow cover force the author’s challenge of Blanford’s hypothesis.
Physically Based Global Downscaling: Climate Change Projections for a Full Century
Authors: Ghan Steven J. , Shippert Timothy 
Published: May 2006

Abstract
A global atmosphere–land model with an embedded subgrid orography scheme is used to simulate the period 1977–2100 using ocean surface conditions and radiative constituent concentrations for a climate change scenario. Climate variables simulated for multiple elevation classes are mapped according to a high-resolution elevation dataset in 10 regions with complex terrain. Analysis of changes in the simulated climate leads to the following conclusions. Changes in surface air temperature and precipitation differ from region to region in a manner similar to simulations without the subgrid scheme. Subgrid elevation contributes little to spatial variability of the change in temperature and the relative change in precipitation. In some regions somewhat greater warming occurs at higher elevations because of the same tendency in the free troposphere, but in others greater warming occurs near the melting level where snow albedo feedback amplifies the warming. Changes in snow water are highly dependent on altitude because of its nonlinear dependence on changes in the melting level. Absolute changes usually increase with altitude because more snow is currently available for depletion, but for extremely cold conditions the simulated warming is insufficient to increase melting. Relative changes in snow water always decrease with altitude as the likelihood that a warming will enhance melting or change the phase of precipitation decreases with decreasing temperature at higher altitudes. In places where snow accumulates, an artificial upper bound on snow water (which is required in any climate model that does not treat lateral snow transport) limits the sensitivity of snow water to climate change considerably. The simulated impact of climate change on regional mean snow water varies widely, with little impact in regions in which the upper bound on snow water is the dominant snow-water sink, moderate impact in regions with a mixture of seasonal and pemanent snow, and profound relative impacts on regions with little permanent snow.
Influence of the Seasonal Cycle on the Termination of El Niño Events in a Coupled General Circulation Model
Authors: Lengaigne Matthieu , Boulanger Jean-Philippe , Menkes Christophe , Spencer Hilary 
Published: May 2006

AbstractIn this study, the mechanisms leading to the El Niño peak and demise are explored through a coupled general circulation model ensemble approach evaluated against observations. The results here suggest that the timing of the peak and demise for intense El Niño events is highly predictable as the evolution of the coupled system is strongly driven by a southward shift of the intense equatorial Pacific westerly anomalies during boreal winter. In fact, this systematic late-year shift drives an intense eastern Pacific thermocline shallowing, constraining a rapid El Niño demise in the following months. This wind shift results from a southward displacement in winter of the central Pacific warmest SSTs in response to the seasonal evolution of solar insolation.In contrast, the intensity of this seasonal feedback mechanism and its impact on the coupled system are significantly weaker in moderate El Niño events, resulting in a less pronounced thermocline shallowing. This shallowing transfers the coupled system into an unstable state in spring but is not sufficient to systematically constrain the equatorial Pacific evolution toward a rapid El Niño termination. However, for some moderate events, the occurrence of intense easterly wind anomalies in the eastern Pacific during that period initiate a rapid surge of cold SSTs leading to La Niña conditions. In other cases, weaker trade winds combined with a slightly deeper thermocline allow the coupled system to maintain a broad warm phase evolving through the entire spring and summer and a delayed El Niño demise, an evolution that is similar to the prolonged 1986/87 El Niño event. La Niña events also show a similar tendency to peak in boreal winter, with characteristics and mechanisms mainly symmetric to those described for moderate El Niño cases.