bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of the Recent Mouse P‐Glycoprotein Structure for Structure‐Based Ligand Design
Authors: Klepsch Freya , Ecker Gerhard F. 
Published: April 2010

AbstractP‐Glycoprotein (P‐gp), a transmembrane, ATP‐dependent drug efflux transporter, has attracted considerable interest both with respect to its role in tumour cell multidrug resistance and in absorption‐distribution and elimination of drugs. Although known since more than 30 years, the understanding of the molecular basis of drug/transporter interaction is still limited, which is mainly due to the lack of structural information available. However, within the past decade X‐ray structures of several bacterial homologues as well as very recently also of mouse P‐gp have become available. Within this review we give an overview on the current status of structural information available and on its impact for structure‐based drug design.
Stress–dilatancy and force chain evolution
Authors: Tordesillas Antoinette , Shi Jingyu , Tshaikiwsky Timothy 
Published: April 2010

AbstractThe evolution of internal structure plays a pivotal role in the macroscopic response of granular materials to applied loads. A case in point is the so‐called ‘stress–dilatancy relation’, a cornerstone of Soil Mechanics. Numerous attempts have been made to unravel the connection between stress–dilatancy and the evolution of fabric and contact forces in a deforming granular medium. We re‐examine this connection in light of the recent findings on force chain evolution, in particular, that of collective force chain failure by buckling. This study is focussed on two‐dimensional deformation of dense granular assemblies. Analysis of individual and collective force chain bucklings is undertaken using data from a discrete element simulation. It is shown that the kinematics of force chain buckling lead to significant levels of local dilatation being developed in the buckling force chain particles and their confining first‐ring neighbors. Findings from the simulation are used to guide the development of a lattice model of collective, localized force chain buckling. Consideration of the statics and kinematics of this process yields a new stress–dilatancy relation. The physics of buckling, even at its simplest form, introduces a richness into the stress–dilatancy formulation in a way that preserves the essential aspects of fabric evolution, specifically the buckling mode. Copyright © 2010 John Wiley & Sons, Ltd.
On the hydraulic intake shape factor for a circular opening located at an impervious boundary: Influence of inclined stratification
Authors: Selvadurai A. P. S. 
Published: April 2010

AbstractIn this paper, we develop an exact closed form solution for a circular entry point located at the interface between an impermeable material and a stratified porous medium, where the principal plane of hydraulic isotropy is inclined to the interface. Copyright © 2010 John Wiley & Sons, Ltd.
Dynamic responses of a poroelastic half‐space from moving trains caused by vertical track irregularities
Authors: Cao Z. G. , Cai Y. Q. , Sun H. L. , Xu C. J. 
Published: April 2010

AbstractThe vibrations of railway tracks on a poroelastic half‐space generated by moving trains are investigated through a vehicle–track–ground coupling model. The theoretical model incorporates a vehicle, a track, and a fully saturated poroelastic half‐space soil medium. The source of vibration excitation is divided into two components: the quasi‐static loads and the dynamic loads. The quasi‐static loads are related to the static component of the axle loads, whereas the dynamic loads are due to the dynamic wheel–rail interaction. A linear Hertizian contact spring is introduced between each wheelset and the rail to consider the dynamic loads. Biot's dynamic theory is used to characterize the poroelastic half‐space soil medium. Using the Fourier transform, the governing equations for the track–ground system are solved and the numerical results are presented for a single axle vehicle model. The different dynamic characteristics of the elastic soil medium and the saturated poroelastic medium are investigated. In addition, the different roles of the moving axle loads and the roughness‐induced dynamic loads are identified. It is concluded that the vibration level of the free field off the track predicted by the poroelastic soil medium is smaller than that predicted by the elastic soil medium for vehicle speed below the Rayleigh wave speed of the poroelastic half‐space, whereas it is larger for vehicle speed above the Rayleigh wave speed. The dynamic loads play an important role in the dynamic responses of the track–ground system. Copyright © 2010 John Wiley & Sons, Ltd.
An efficient dynamic group key agreement protocol for imbalanced wireless networks
Authors: Chuang Yun‐Hsin , Tseng Yuh‐Min 
Published: April 2010

AbstractOwing to the popularity of wireless networks, the group key agreement (GKA) design is critical for providing secure group communications over an insecure wireless channel. In 2005, Namet al.proposed a GKA protocol for imbalanced wireless networks in which an imbalanced wireless network consists of many mobile nodes with limited computing capability and a powerful node with less restriction. In 2007, Tseng showed that Namet al.'s protocol is not a contributory GKA, while he also proposed a new GKA protocol. However, neither GKA protocol is concerned with dynamic member joining/leaving. This is an important functionality of GKA, especially for a wireless network environment. In this paper, we propose a dynamic group key agreement protocol for imbalanced wireless networks, and show that it requires less computation cost for dynamic member joining/leaving as compared to the previously proposed protocols. We also show that the proposed protocol is provably secure against passive attacks under the decision Diffie–Hellman problem and the hash function assumptions. Furthermore, by the pre‐shared two‐party key between a mobile node and the powerful node in the existing imbalanced wireless networks, we propose a generalized GKA protocol that requires only several hash functions. Copyright © 2010 John Wiley & Sons, Ltd.
An immunological approach for file recovery over JXTA peer‐to‐peer framework
Authors: Nassef Mohammad , Badr Amr , Farag Ibrahim 
Published: April 2010

AbstractPeer‐to‐peer (P2P) file‐sharing systems are characterized by highly replicated content that is distributed among nodes with enormous aggregate resources for storage and communication. File consistency is often compromised by undesirable changes, which should be detected and corrected in a timely fashion. The artificial immune system (AIS) is a novel evolutionary paradigm inspired by aspects of the biological immune system (BIS), such as protection, decentralization, autonomy, and anomaly detection. The AIS paradigm suggests a wide variety of mechanisms for solving complex computer problems. In this paper, we propose the ImmunoJXTA framework for file consistency management and file recovery using the main aspects of AIS in P2P systems. We implemented ImmunoJXTA on the JXTA P2P framework to recover distributed inconsistent files between peers efficiently. Promising results are achieved from experimental runs of the proposed framework. Copyright © 2010 John Wiley & Sons, Ltd.
Accessing posttranslationally modified proteins through thiol positioning
Authors: Kumar K. S. Ajish , Brik Ashraf 
Published: April 2010

AbstractThe field of peptide synthesis achieved considerable advancement in the last decade with the discovery of native chemical ligation (NCL). With the aim of broader application of ligation methods in the synthesis of proteins several strategies have been developed. One of the significant contributions to NCL based strategies is the desulfurization reaction, which removes the thiol handle to generate the unmodified protein. The principle of NCL coupled with desulfurization is effortlessly executed in the synthesis of posttranslationally modified proteins. This short account will cover the recent developments on how new methods of chemical ligation is being evolved and exploited in achieving posttranslationally modified proteins. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Study on capacitive Frisch grid CdZnTe detector parameter optimization and fabrication
Authors: Hu Dongni , Wang Linjun , Min Jiahua , Qin Kaifeng , Zhang Jijun , Huang Jian , Xia Yiben 
Published: April 2010

AbstractIn this paper, the design parameters of the cylindrical capacitive Frisch grid CdZnTe detector were optimized through a finite‐element simulation method using ANSYS software, based on a 3‐dimensional weighting potential analysis for the first time. The weighting potential distributions of the model with the different ratio of screen length to device height (L /H), insulator thickness (d), insulator relative permittivity (εr), electrode areas of anode and the ratio of anode diameter to device height (D /H), were studied. The optimized parameters with an L /H value of 80%, d /εr< 0.05 mm, the anode diameter of about 2 mm and a D /H value <1/2, were obtained. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement of electrical properties of AlGaN/GaN heterostructures using multiple high‐temperature AlN interlayers
Authors: Ni J. Y. , Hao Y. , Xue J. S. , Xu Z. H. , Zhang Z. F. , Zhang J. C. , Yang L. A. , Zhang J. F. 
Published: April 2010

AbstractAlGaN/GaN heterostructures with multiple AlN interlayers deposited at a high‐temperature (HT) of 900 °C were grown by metalorganic chemical vapor deposition. Flat surface with few dark pits was obtained by using multiple HT‐AlN interlayers. Hall effect measurements and non‐contact sheet resistance mappings demonstrated the improvement of the electrical properties of AlGaN/GaN heterostructure. The sheet carrier density and Hall mobility continuously increased with the increase of the AlN interlayer number. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the piezoelectric constant on the electronic structure of wurtzite InGaN quantum dots
Authors: Hong Kuo‐Bin , Tsai Wei‐Yi , Kuo Mao‐Kuen 
Published: April 2010

AbstractWe investigate the electromechanical fields and transition energies of strained wurtzite InGaN quantum dot nanostructures. Electromechanical fields induced by lattice mismatches in heterostructures, both in and around quantum dots, are analyzed by using fully‐coupled electromechanical equations. The 4×4 Hamiltonian for the wurtzite structure is modified by incorporating the effects of electromechanical fields into the confinement potential and is then analyzed numerically using th the finite element method. The calculated piezoelectric potential is larger if the piezoelectric constant e15 is included in the numerical model. Comparing the cases of e15 = 0 and e15 ≠ 0, we find large discrepancies both in the piezoelectric potential and in the transition energy. This result also suggests that the shear strain effect cannot be neglected for strained wurtzite InGaN quantum dots. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear polarized photoluminescence from GaN quantum dots imbedded in AlN matrix
Authors: Zhuravlev K. S. , Aleksandrov I. A. , Holtz P.‐O. 
Published: April 2010

AbstractWe report microphotoluminescence studies of GaN/AlN quantum dots grown along the (0001) crystal axis by molecular‐beam epitaxy on sapphire substrates. To obtain quantum dots with different density and size a nominal GaN coverage was varied from 1 to 4 monolayers. The highest density of quantum dots was about 1011 cm‐2, so about 103 quantum dots was excited in experiments. We found that the photoluminescence intensity of a sample with the smallest amount of deposited GaN decreases in more than two orders of magnitude under continuous‐wave laser exposure during about 30 minutes and then it remains stable. The photoluminescence intensity of the rest samples was time‐independent quantity. The emission band of the former sample exhibits a prominent linear polarization along the growth plane. We assume that the quite high degree of polarization can be due anisotropy of strain and/or shape of the quantum dots formed near dislocations which act also as recombination centers causing photoluminescence quenching. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Failure analysis of InGaN/GaN LEDs with emission wavelength between 440 nm and 550 nm
Authors: Li Z. L. , Lai P. T. , Choi H. W. 
Published: April 2010

AbstractWhile longer wavelength emission from InGaN/GaN light‐emitting diodes can be achieved by increasing the Indium (In) content in the qunatum wells, the increased In content gives rise to side‐effects to the material and device performance and reliability. It was found that the induced strain in the wafer and the density of threading dislocations increases with increasing In content. From current‐voltage and 1/f noise measurements, it was observed that the leakage currents, static resistance and noise magnitudes rises monotonically with increasing emission wavelength (In composition), which can be attributed to higher defect concentrations. After undergoing a 1000‐hr reliability test, it was discovered that the optical degradation rates for the longer wavelength green LEDs were significantly higher than those of shorter wavelength. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Correlation between growth pits, optical and structural properties of AlGaN/GaN high‐electron‐mobility transistors on 4″ silicon substrate
Authors: Khai Pum Chian , Suzue Takaaki , Sakai Yusuke , Selvaraj S. Lawrence , Egawa Takashi , Jimbo Takashi 
Published: April 2010

AbstractWe report growth pits, structural, electrical, and optical data for AlGaN/GaN HEMT samples grown on 4″ silicon substrates. The samples in this study were all grown on 4″ p‐Si (111) substrate by metalorganic chemical vapor deposition (MOCVD). Optical microscopy, Hall‐effect measurements, photoluminescence, high resolution X‐ray Diffraction (HRXRD) were performed to investigate the morphological, electrical and optical properties and crystal quality of the samples. According to these data, the relationship between the growth pits, optical and structural properties were studied (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical characterization of (11‐22) semipolar GaN on m ‐plane sapphire without low temperature buffer layer
Authors: Lee Sung‐Nam , Kim K. K. , Nam O. H. , Kim J. H. , Kim H. 
Published: April 2010

AbstractWe reported the high quality semipolar (11‐22) GaN grown on m‐sapphire by using the novel two‐step growth method without low temperature GaN or AlN buffer layer. It is found that macroscopic surface morphology of semipolar GaN epilayer was very smooth, while microscopic surface structure was arrowhead‐like surface structure toward the direction of [1‐21‐1]. Anisotropic crystal properties of semipolar GaN/m‐sapphire were also observed by two incident directions of X‐ray beam. Therefore, we suggested that the anisotropic crystal properties and arrow‐head like surface structure would be caused by heteroepitaxial crystallograhpic difference between semipolar GaN and m‐sapphire. Additionally, photoluminescence (PL) measurements showed the strong bandedge emission of n‐type semipolar GaN without yellow luminescence (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiple lightning strokes
Authors: Allibone T. E. 
Published: April 2010

AbstractAn analysis is given of 19 consecutive photographs of lightning taken during a storm on July 11, 1941, in Cheshire. The camera was oscillated by hand during the whole of the storm in order to separate the component strokes of each flash. The average number of strokes per flash was found to be nearly four, and more than 90 per cent of all the flashes were composed of two or more strokes. The results are compared with those obtained elsewhere by different technique.
Some design issues in phase 2B vs phase 3 prevention trials for testing efficacy of products or concepts
Authors: Gilbert Peter B. 
Published: April 2010

AbstractAfter one or more Phase 2 trials show that a candidate preventive vaccine induces immune responses that putatively protect against an infectious disease for which there is no licensed vaccine, the next step is to evaluate the efficacy of the candidate. The trial‐designer faces the question of what is the optimal size of the initial efficacy trial? Part of the answer will entail deciding between a large Phase 3 licensure trial or an intermediate‐sized Phase 2b screening trial, the latter of which may be designed to directly contribute to the evidence‐base for licensing the candidate, or, to test a scientific concept for moving the vaccine field forward, acknowledging that the particular candidate will never be licensable. Using the HIV vaccine field as a case study, we describe distinguishing marks of Phase 2b and Phase 3 prevention efficacy trials, and compare the expected utility of these trial types using Pascal's decision‐theoretic framework. By integrating values/utilities on (1) correct or incorrect conclusions resulting from the trial; (2) timeliness of obtaining the trial results; (3) precision for estimating the intervention effect; and (4) resources expended; this decision framework provides a more complete approach to selecting the optimal efficacy
trial size than a traditional approach that is based primarily on power calculations. Our objective is to help inform the decision‐process for planning an initial efficacy trial design. Copyright © 2010 John Wiley & Sons, Ltd.
Model‐based phase I designs incorporating toxicity and efficacy for single and dual agent drug combinations: Methods and challenges
Authors: Mandrekar Sumithra J. , Qin Rui , Sargent Daniel J. 
Published: April 2010

AbstractNovel therapies are challenging the standards of drug development. Agents with specific biologic targets, unknown dose‐efficacy curves, and limited toxicity mandate novel designs to identify biologically optimal doses. We review two model‐based designs that utilize either a proportional odds model or a continuation ratio model to identify an optimal dose of a single or two‐agent combination in a Phase I setting utilizing both toxicity and efficacy data. A continual reassessment method with straightforward dose selection criterion using accumulated data from all patients treated until that time point is employed while allowing for separate toxicity and efficacy curves for each drug in a two‐drug setting. The simulation studies demonstrate considerable promise, at least theoretically, in the ability of such model‐based designs to identify the optimal dose. Despite such favorable operating characteristics, there are several pragmatic challenges that hinder the routine implementation of such model‐based designs in practice. We review and offer practical solutions to potentially overcome some of these challenges. The acceptance and integration of these designs in practice may be quicker and easier if they are developed in concert with a clinical paradigm. Copyright © 2010 John Wiley & Sons, Ltd.
The statistics of phase 0 trials
Authors: Rubinstein Larry V. , Steinberg Seth M. , Kummar Shivaani , Kinders Robert , Parchment Ralph E. , Murgo Anthony J. , Tomaszewski Joseph E. , Doroshow James H. 
Published: April 2010

AbstractThe PD‐driven phase 0 trial is a new form, designed to be a first‐in‐man study, often of a new agent, conducted to assess drug effect on a molecular target, by means of a pharmacodynamic (PD) assay, in a very small number (10–15) of patients. Such a study is meant to be a proof of principle trial to determine whether the agent yields the PD effect predicted by pre‐clinical studies. The dosage is meant to be pharmacologically active, but is neither toxic nor likely to yield clinical benefit. Such a trial may be used to serve as a very early test of an agent's biologic effect, allowing for early weeding out of ineffective agents, or as an early means of determining the most promising of competing analogue agents. This manuscript will present designs for such PD‐driven studies that are statistically efficient and rigorous, focusing on non‐comparative trials. The phase 0 trial promises to become an increasingly important tool for facilitating and speeding the development of new therapeutic agents, particularly in oncology. Copyright © 2010 John Wiley & Sons, Ltd.
Joint Bayesian analysis of birthweight and censored gestational age using finite mixture models
Authors: Schwartz Scott L. , Gelfand Alan E. , Miranda Marie L. 
Published: April 2010

AbstractBirthweight and gestational age are closely related and represent important indicators of a healthy pregnancy. Customary modeling for birthweight is conditional on gestational age. However,jointmodeling directly addresses the relationship between gestational age and birthweight, and provides increased flexibility and interpretation as well as a strategy to avoid using gestational age as an intermediate variable. Previous proposals have utilized finite mixtures of bivariate regression models to incorporate well‐established risk factors into analysis (e.g. sex and birth order of the baby, maternal age, race, and tobacco use) while examining the non‐Gaussian shape of the joint birthweight and gestational age distribution. We build on this approach by demonstrating the inferential (prognostic) benefits of joint modeling (e.g. investigation of ‘age inappropriate’ outcomes likesmall for gestational age) and hence re‐emphasize the importance of capturing the non‐Gaussian distributional shapes. We additionally extend current models through a latent specification which admits interval‐censored gestational age. We work within a Bayesian framework which enables inference beyond customary parameter estimation and prediction as well as exact uncertainty assessment. The model is applied to a portion of the 2003–2006 North Carolina Detailed Birth Record data (n=336129) available through the Children's Environmental Health Initiative and is fitted using the Bayesian methodology and Markov chain Monte Carlo approaches. Copyright © 2010 John Wiley & Sons, Ltd.
Estimating treated prevalence and service utilization rates: Assessing disparities in mental health
Authors: Laska Eugene M. , Meisner Morris , Wanderling Joseph , Siegel Carole 
Published: April 2010

AbstractThere is considerable public concern about health disparities among different cultural/racial/ethnic groups. Important process measures that might reflect inequities are treated prevalence and the service utilization rate in a defined period of time. We have previously described a method for estimatingN, the distinct number who received service in a year, from a survey of service users at a single point in time. The estimator is based on the random variable ‘time since last service’, which enables the estimation of treated prevalence. We show that this same data can be used to estimate the service utilization rate,E(J), the mean number of services in the year. If the sample istypicalwith respect to the time since last visit, the MLE ofE(J) is asymptotically unbiased. Confidence intervals and a global test of equality of treated prevalence and service utilization rates among several groups are given. A data set of outpatient mental health services from a county in New York State for which the true values of the parameters are known is analyzed as an illustration of the methods and an appraisal of their accuracy. Copyright © 2010 John Wiley & Sons, Ltd.