bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two Improved Mixture Weibull Models for the Analysis of Wind Speed Data
Authors: Qin Xu , Zhang Jiang-she , Yan Xiao-dong 
Published: April 2012

AbstractIn this paper, the authors propose two improved mixture Weibull distribution models by adding one or two location parameters to the existing two-component mixture two-parameter Weibull distribution [MWbl(2, 2)] model. One improved model is the mixture two-parameter Weibull and three-parameter Weibull distribution [MWbl(2, 3)] model. The other improved model is the two-component mixture three-parameter Weibull distribution [MWbl(3, 3)] model. In contrast to existing literature, which has focused on the MWbl(2, 2) and the typical Weibull distribution models, the authors apply the MWbl(2, 3) model and MWbl(3, 3) model to fit the distribution of wind speed data with nearly zero percentages of null wind speed. The parameters of the two improved models are estimated by the maximum likelihood method in which the maximization problem is regarded as a nonlinear programming problem with only inequality constraints and is solved numerically by the interior-point method. The experimental results show that the mixture Weibull models proposed in this paper are more flexible than the existing models for the analysis of wind speed data in practice.
Optimizing Input Data for Gridding Climate Normals for Canada
Authors: Hopkinson Ron F. , Hutchinson Michael F. , McKenney Daniel W. , Milewska Ewa J. , Papadopol Pia 
Published: April 2012

AbstractSpatial models of 1971–2000 monthly climate normals for daily maximum and minimum temperature and total precipitation are required for many applications. The World Meteorological Organization’s recommended standard for the calculation of a normal value is a complete 30-yr record with a minimal amount of missing data. Only 650 stations (~16%) in Canada meet this criterion for the period 1971–2000. Thin-plate smoothing-spline analyses, as implemented by the Australian National University Splines (ANUSPLIN) package, are used to assess the utility of differing amounts of station data in estimating nationwide monthly climate normals. The data include 1) only those stations (1169) with 20 or more years of data, 2) all stations (3835) with 5 or more years of data in at least one month, and 3) as in case 2 but with data adjusted through the most statistically significant linear-regression relationship with a nearby long-term station to 20 or more years (3983 stations). Withheld-station tests indicate that the regression-adjusted normals as in dataset 3 generally yield the best results for all three climatological elements, but the unadjusted normals as in dataset 2 are competitive with the adjusted normals in spring and autumn, reflecting the known longer spatial correlation scales in these seasons. The summary mean absolute differences between the ANUSPLIN estimates and the observations at 48 spatially representative withheld stations for dataset 3 are 0.36°C, 0.66°C, and 4.7 mm, respectively, for maximum temperature, minimum temperature, and precipitation. These are respectively 18%, 7%, and 18% smaller than the summary mean absolute differences for the long-term normals in dataset 1.
Hypercooling in the Nocturnal Boundary Layer: Broadband Emissivity Schemes
Authors: Ponnulakshmi V. K. , Mukund V. , Singh D. K. , Sreenivas K. R. , Subramanian G. 
Published: April 2012

AbstractBroadband flux emissivity schemes are often used to model infrared radiative exchanges in the atmosphere. In particular, such schemes help highlight the interaction of radiation with other transport processes, an aspect that is crucial to an understanding of phenomena relevant to the nocturnal boundary layer (NBL). Although the original schemes were restricted to radiatively black bounding surfaces, an extension of the same to nonblack surfaces has since been frequently used in NBL modeling. Herein, it is shown that the nonblack extension is erroneous and leads to a spurious yet intense near-surface cooling in the opaque bands. This paper presents the correct formulation that eliminates this cooling and discusses in some detail earlier NBL calculations affected by this error.
A Theory of Topographically Bound Balanced Motions and Application to Atmospheric Low-Level Jets
Authors: Silvers Levi G. , Schubert Wayne H. 
Published: April 2012

Abstract
The subject of this study is topographically bound low-level jets, such as the South American summertime low-level jet on the eastern side of the Andes and its companion, the Chilean low-level jet on the western side of the Andes. These jets are interpreted as balanced flows that obey the potential vorticity invertibility principle. This invertibility principle is expressed in isentropic coordinates, and the mathematical issue of isentropes that intersect the topography is treated by the method of a massless layer. In this way, the low-level jets on the western and eastern sides of the Andes can both be attributed to the infinite potential vorticity that lies in the infinitesimally thin massless layer on the topographic feature. To obtain a cyclonic flow centered on the topographic feature, the mountain crest must have been heated enough to draw down the overlying isentropic surfaces; otherwise, isentropic surfaces bend upward at the mountain crest and an anticyclonic flow is produced. Both anticyclonic and cyclonic solutions are obtained here using analytical and numerical methods to solve the invertibility principle. The summertime topographically bound flows discussed here are quite distinct from the wintertime Rossby wave train patterns that occur when strong westerlies impinge on the topography.
An Analytical Model of the Response of the Meridional Overturning Circulation to Changes in Wind and Buoyancy Forcing
Authors: Shakespeare Callum J. , McC. Hogg Andrew 
Published: April 2012

Abstract
An analytical model of the full-depth ocean stratification and meridional overturning circulation for an idealized Atlantic basin with a circumpolar channel is presented. The model explicitly describes the ocean response to both Southern Ocean winds and the global pattern and strength of prescribed surface buoyancy fluxes. The construction of three layers, defined by the two isopycnals of overturning extrema, allows the description of circulation and stratification in both the upper and abyssal ocean. The system is fully solved in the adiabatic limit to yield scales for the surface layer thickness, buoyancies of each layer, and overturning magnitudes. The analytical model also allows scaling of the Antarctic Circumpolar Current (ACC) transport. The veracity of the three-layer framework and derived scales is confirmed by applying the analytical model to an idealized geometry, eddy-permitting ocean general circulation model.
Consistent with previous results, the abyssal overturning is found to scale inversely with wind stress, whereas the North Atlantic overturning and surface-layer thickness scale linearly with wind stress. In terms of the prescribed surface buoyancy fluxes, increased negative fluxes (buoyancy removal) in the North Atlantic increase the North Atlantic overturning and surface-layer thickness, whereas increased positive fluxes in the middle and low latitudes lead to a decrease in both parameters. Increased negative surface buoyancy fluxes to the south of Drake Passage increase the abyssal overturning and reduce the abyssal buoyancy. The ACC transport scales to first order with the sum of the Ekman transport and the abyssal overturning and thus increases with both wind stress and southern surface buoyancy flux magnitude.
Chloroplastic Hsp100 chaperones ClpC2 and ClpD interact in vitro with a transit peptide only when it is located at the N-terminus of a protein
Authors: Bruch Eduardo M , Rosano Germán L , Ceccarelli Eduardo A 
Published: April 2012

AbstractBackgroundClp/Hsp100 chaperones are involved in protein quality control. They act as independent units or in conjunction with a proteolytic core to degrade irreversibly damaged proteins. Clp chaperones from plant chloroplasts have been also implicated in the process of precursor import, along with Hsp70 chaperones. They are thought to pull the precursors in as the transit peptides enter the organelle. How Clp chaperones identify their substrates and engage in their processing is not known. This information may lie in the position, sequence or structure of the Clp recognition motifs.ResultsWe tested the influence of the position of the transit peptide on the interaction with two chloroplastic Clp chaperones, ClpC2 and ClpD fromArabidopsis thaliana(AtClpC2 and AtClpD). The transit peptide of ferredoxin-NADP+reductase was fused to either the N- or C-terminal end of glutathioneS-transferase. Another fusion with the transit peptide interleaved between two folded proteins was used to probe if AtClpC2 and AtClpD could recognize tags located in the interior of a polypeptide. We also used a mutated transit peptide that is not targeted by Hsp70 chaperones (TP1234), yet it is imported at a normal rate. The fusions were immobilized on resins and the purified recombinant chaperones were added. After a washing protocol, the amount of bound chaperone was assessed. Both AtClpC2 and AtClpD interacted with the transit peptides when they were located at the N-terminal position of a protein, but not when they were allocated to the C-terminal end or at the interior of a polypeptide.ConclusionsAtClpC2 and AtClpD have a positional preference for interacting with a transit peptide. In particular, the localization of the signal sequence at the N-terminal end of a protein seems mandatory for interaction to take place. Our results have implications for the understanding of protein quality control and precursor import in chloroplasts.
Phylogeographic analysis reveals significant spatial genetic structure of Incarvillea sinensisas a product of mountain building
Authors: Chen Shaotian , Xing Yaowu , Su Tao , Zhou Zhekun , Dilcher Emeritus David L , Soltis Douglas E 
Published: April 2012

AbstractBackgroundIncarvillea sinensisis widely distributed from Southwest China to Northeast China and in the Russian Far East. The distribution of this species was thought to be influenced by the uplift of the Qinghai-Tibet Plateau and Quaternary glaciation. To reveal the imprints of geological events on the spatial genetic structure ofIncarvillea sinensis, we examined two cpDNA segments (trnH-psbA andtrnS-trnfM) in 705 individuals from 47 localities.ResultsA total of 16 haplotypes was identified, and significant genetic differentiation was revealed (GST=0.843,NST = 0.975, P < 0.05). The survey detected two highly divergent cpDNA lineages connected by a deep gap with allopatric distributions: the southern lineage with higher genetic diversity and differentiation in the eastern Qinghai-Tibet Plateau, and the northern lineage in the region outside the Qinghai-Tibet Plateau. The divergence between these two lineages was estimated at 4.4 MYA. A correlation between the genetic and the geographic distances indicates that genetic drift was more influential than gene flow in the northern clade with lower diversity and divergence. However, a scenario of regional equilibrium between gene flow and drift was shown for the southern clade. The feature of spatial distribution of the genetic diversity of the southern lineage possibly indicated that allopatric fragmentation was dominant in the collections from the eastern Qinghai-Tibet Plateau.ConclusionsThe results revealed that the uplift of the Qinghai-Tibet Plateau likely resulted in the significant divergence between the lineage in the eastern Qinghai-Tibet Plateau and the other one outside this area. The diverse niches in the eastern Qinghai-Tibet Plateau created a wide spectrum of habitats to accumulate and accommodate new mutations. The features of genetic diversity of populations outside the eastern Qinghai-Tibet Plateau seemed to reveal the imprints of extinction during the Glacial and the interglacial and postglacial recolonization. Our study is a typical case of the significance of the uplift of the Qinghai-Tibet Plateau and the Quaternary Glacial in spatial genetic structure of eastern Asian plants, and sheds new light on the evolution of biodiversity in the Qinghai-Tibet Plateau at the intraspecies level.
The validation of a French-language version of the Aging Perceptions Questionnaire (APQ) and its extension to a population aged 55 and over
Authors: Ingrand Isabelle , Houeto Jean Luc , Gil Roger , Gee Hannah Mc , Ingrand Pierre , Paccalin Marc 
Published: April 2012

Abstract

Background
Several studies have shown the influence of the perceptions of aging on the cognitive functioning and the mental and physical health of older people. These relationships have not to date been studied in France where validated instruments are lacking. The primary objective of this study was to validate a French-language version of the Aging Perceptions Questionnaire (APQ) in the French general population aged 65 and over. The secondary objective was to study the stability of the dimensions of this instrument among participants aged 55 to 64.

Methods
The study was proposed to the cohort of the Observatoire Régional du Vieillissement (OPREVI) (observatory of aging), located in a small town in Poitou-Charentes (western France). An anonymous questionnaire including the APQ was sent by mail to inhabitants aged 55 and over. The original English language APQ was described with adults aged 65 and older. It has 32 items distributed on 7 dimensions: timeline chronic and cyclical, positive and negative consequences, positive and negative control and emotional representations.

Results
656 adults participated in this survey (286 men, 370 women). Among those aged 65 and over (n = 394), the seven-factor structure estimated by confirmatory factor analysis was coherent with original findings. Internal consistency as evaluated by Cronbach alpha, was between 0.83 for consequences negative and 0.52 for control negative. Several dimensions were strongly correlated. Among participants aged 55 to 64 (n = 262), the same factorial model yielded an acceptable fit. Multi-group confirmatory factor analysis concluded to approximate factorial invariance between the two age groups with a null delta in comparative fit index.

Conclusion
This study among French people aged 65 and over, added further evidence of the multidimensional structure of the French version of the APQ which is superimposed to the dimensions of the original Irish version. The same factorial structure applies acceptably to the younger group (aged 55–64). The OPREVI study is ongoing, and will collect data on the physical, material and social characteristics of participants. It will therefore be possible to analyse the variables associated with the perceptions of aging. On the basis of an individual's perceptions of aging as captured by this questionnaire, and his or her clinical profile, tailored multi-dimensional assistance could be made available aiming to provide incentives to anticipate or to adapt to difficulties.
Advanced glycation end products impair the migration, adhesion and secretion potentials of late endothelial progenitor cells
Authors: Li Hong , Zhang Xiaoyun , Guan Xiumei , Cui Xiaodong , Wang Yuliang , Chu Hairong , Cheng Min 
Published: April 2012

AbstractBackgroundEndothelial progenitor cells (EPCs), especially late EPCs, play a critical role in endothelial maintenance and repair, and postnatal vasculogenesis. Advanced glycation end products (AGEs) have been shown to impair EPC functions, such as proliferation, migration and adhesion. However, their role in the regulation of the production of vasoactive substances in late EPCs is less well defined.MethodsPassages of 3~5 EPCs, namely late EPCs, were cultured with different concentrations (0~500 μg/ml) of AGEs, and the apoptosis, adhesion and migration were subsequently determined. The release of vasoactive substances, such as stromal cell-derived factor-1 (SDF-1), nitric oxide (NO), prostaglandin I2(PGI2), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), and in addition the activity of superoxide dismutase (SOD), were evaluated by ELISA. At the same time, the gene and protein expressions of CXCR4 were assayed by real-time RT-PCR and western-blot.ResultsAGEs promoted late EPC apoptosis. Moreover, AGEs impaired late EPC migration and adhesion in a concentration-dependent manner. Accordingly, the production of SDF-1 was decreased by AGEs. Although the CXCR4 expressions of late EPCs were up-regulated for AGE concentrations of 50, 100 or 200 μg/ml, a marked decrease was observed for the higher concentration of 500 μg/ml. Furthermore, co-culturing with AGEs decreased the levels of NO, t-PA, PGI2,and the activity of SOD but up-regulated the production of PAI-1.ConclusionOur data provide evidence that AGEs play an important role in impairing late EPC functions, which could contribute to the development of vascular diseases in diabetes.
Benzoic acid fermentation from starch and cellulose via a plant-like β-oxidation pathway in Streptomyces maritimus
Authors: Noda Shuhei , Kitazono Eiichi , Tanaka Tsutomu , Ogino Chiaki , Kondo Akihiko 
Published: April 2012

Abstract

Background
Benzoic acid is one of the most useful aromatic compounds. Despite its versatility and simple structure, benzoic acid production using microbes has not been reported previously. Streptomyces are aerobic, Gram-positive, mycelia-forming soil bacteria, and are known to produce various kinds of antibiotics composed of many aromatic residues. S. maritimus possess a complex amino acid modification pathway and can serve as a new platform microbe to produce aromatic building-block compounds. In this study, we carried out benzoate fermentation using S. maritimus. In order to enhance benzoate productivity using cellulose as the carbon source, we constructed endo-glucanase secreting S. maritimus.

Results
After 4 days of cultivation using glucose, cellobiose, or starch as a carbon source, the maximal level of benzoate reached 257, 337, and 460 mg/l, respectively. S. maritimus expressed β-glucosidase and high amylase-retaining activity compared to those of S. lividans and S. coelicolor. In addition, for effective benzoate production from cellulosic materials, we constructed endo-glucanase-secreting S. maritimus. This transformant efficiently degraded the phosphoric acid swollen cellulose (PASC) and then produced 125 mg/l benzoate.

Conclusions
Wild-type S. maritimus produce benzoate via a plant-like β-oxidation pathway and can assimilate various carbon sources for benzoate production. In order to encourage cellulose degradation and improve benzoate productivity from cellulose, we constructed endo-glucanase-secreting S. maritimus. Using this transformant, we also demonstrated the direct fermentation of benzoate from cellulose. To achieve further benzoate productivity, the L-phenylalanine availability needs to be improved in future.
Inaugural meeting of the malaria policy advisory committee to the WHO: conclusions and recommendations
Authors:   WHO Malaria Policy Advisory Committee and Secretariat
Published: April 2012

Abstract
The Malaria Policy Advisory Committee to the World Health Organization met for the first time from 31 January to 2 February 2012 in Geneva, Switzerland. This article provides a summary of the discussions, conclusions and recommendations from that meeting, as part of the newly launched Malaria Journal thematic series “WHO Malaria Policy Advisory Committee: Reports and Recommendations”.
Summaries are provided, referencing the relevant background documents, for the meeting sessions on global malaria control, drug resistance and containment, rapid diagnostic test procurement criteria, larviciding, classification of countries for elimination, estimating malaria cases and deaths, and seasonal malaria chemoprevention. Policy statements, position statements, and guidelines that will arise from the MPAC meeting conclusions and recommendations will be formally issued and disseminated to World Health Organization member states by the World Health Organization Global Malaria Programme.
Prospects of implant with locking plate in fixation of subtrochanteric fracture: experimental demonstration of its potential benefits on synthetic femur model with supportive hierarchical nonlinear hyperelastic finite element analysis
Authors: Latifi Mohammed Hadi , Ganthel Kunalan , Rukmanikanthan Shanmugam , Mansor Azura , Kamarul Tunku , Bilgen Mehmet 
Published: April 2012

Abstract

Background
Effective fixation of fracture requires careful selection of a suitable implant to provide stability and durability. Implant with a feature of locking plate (LP) has been used widely for treating distal fractures in femur because of its favourable clinical outcome, but its potential in fixing proximal fractures in the subtrochancteric region has yet to be explored. Therefore, this comparative study was undertaken to demonstrate the merits of the LP implant in treating the subtrochancteric fracture by comparing its performance limits against those obtained with the more traditional implants; angle blade plate (ABP) and dynamic condylar screw plate (DCSP).

Materials and Methods
Nine standard composite femurs were acquired, divided into three groups and fixed with LP (n = 3), ABP (n = 3) and DCSP (n = 3). The fracture was modeled by a 20 mm gap created at the subtrochanteric region to experimentally study the biomechanical response of each implant under both static and dynamic axial loading paradigms. To confirm the experimental findings and to understand the critical interactions at the boundaries, the synthetic femur/implant systems were numerically analyzed by constructing hierarchical finite element models with nonlinear hyperelastic properties. The predictions from the analyses were then compared against the experimental measurements to demonstrate the validity of each numeric model, and to characterize the internal load distribution in the femur and load bearing properties of each implant.

Results
The average measurements indicated that the constructs with ABP, DCPS and LP respectively had overall stiffness values of 70.9, 110.2 and 131.4 N/mm, and exhibited reversible deformations of 12.4, 4.9 and 4.1 mm when the applied dynamic load was 400 N and plastic deformations of 11.3, 2.4 and 1.4 mm when the load was 1000 N. The corresponding peak cyclic loads to failure were 1100, 1167 and 1600 N. The errors between the displacements measured experimentally or predicted by the nonlinear hierarchical hyperelastic model were less than 18 %. In the implanted femur heads, the principal stresses were spatially heterogeneous for ABP and DCSP but more homogenous for LP, meaning LP had lower stress concentrations.

Conclusion
When fixed with the LP implant, the synthetic femur model of the subtrochancteric fracture consistently exceeds in the key biomechanical measures of stability and durability. These capabilities suggest increased resistance to fatigue and failure, which are highly desirable features expected of functional implants and hence make the LP implant potentially a viable alternative to the conventional ABP or DCSP in the treatment of subtrochancteric femur fractures for the betterment of clinical outcome.