bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation of cylindrical microdomains of triblock copolymers byin situstress–strain‐ birefringence measurements
Authors: Shimizu Kenichi , Saito Hiromu
Published: February 2009

The orientation behavior of polystyrene‐block‐hydrogenated polyisoprene‐block‐polystyrene (SEPS) with cylindrical microdomains of polystyrene (PS) dispersed in the rubbery segments was investigated by simultaneous measurements of stress and birefringence during uniaxial stretching. The stress increased sharply with strain below the yield strain and then it gradually increased. In contrast, the birefringence changed little below the yield strain, increased sharply with strain above the yield strain up to a strain of 0.5, and then gradually increased. The characteristic birefringence behavior is attributed to the form birefringence induced by the orientation and the parallel arrangement of the cylindrical microdomains associated with the orientation of the rubbery segments. The orientation function of the cylindrical microdomainsfevaluated by analyzing the form birefringence agrees well with that obtained from the SAXS result. Thefwas almost zero below the yield strain and it increased sharply with strain up to a strain of 0.5 and then was constant above a strain of 0.5. These results suggest that the orientation of the cylindrical microdomains occur above the yield strain up to a strain of 0.5 and that the orientation does not increase above a strain of 0.5 in spite of the continuous orientation of the rubbery ethylene–propylene segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 715–723, 2009
A novel route to in‐situ incorporation of silver nanoparticles into supramolecular hydrogel networks
Authors: Ma Dong , Xie Xi , Zhang Li‐Ming
Published: February 2009

A novel strategy was developed for the in situ incorporation of silver nanoparticles into the supramolecular hydrogel networks, in which colloidally stable silver hydrosols were firstly prepared in the presence of an amphiphilic block copolymer of poly(oxyethylene)‐poly(oxypropylene)‐poly(oxyethylene) and then mixed with aqueous solution of α‐cyclodextrin. The analyses from rheology, X‐ray diffraction, and scanning electron microscopy confirmed the formation of the supramolecular‐structured hydrogels hybridized with silver nanoparticles. In particular, the colloidal stability of the resultant silver hydrosol and its gelation kinetics in the presence of α‐cyclodextrin as well as the viscoelastic properties of the resultant hybrid hydrogel were investigated under various concentrations of the used block copolymer. It was found that the used block copolymer could act not only as the effective reducing and stabilizing agents for the preparation of the silver hydrosol but also as the effective guest molecule for the supramolecular self‐assembly with α‐cyclodextrin. In addition, the effects of silver nanoparticles on the gelation process and the hydrogel strength were also studied. Such a hybrid hydrogel material could show a good catalytic activity for the reduction of methylene blue dye by sodium borohydride. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 740–749, 2009
Theoretical investigations on the carbazole‐based conjugated polymers containing electron‐donating divinylaryl
Authors: Liu Liming , Wang Xueye , Wang Yanling , Peng Xinyu , Mo Yuexiang
Published: February 2009

The polycarbazoles have been proved to efficiently suppress the keto defect emission. Three carbazole‐based conjugated polymers, poly[9‐methyl‐3‐(4‐vinylstyryl)‐9H‐carbazole] (PBC), poly[9‐methyl‐3‐(2‐(5‐vinylthiophen‐2‐yl)vinyl)‐9H‐carbazole] (PBT) and poly[9‐methyl‐3‐(2‐(5‐vinylfuran‐2‐yl)vinyl)‐9H‐carbazole] (PBF), were investigated by quantum‐chemical techniques, and gain a detailed understanding of the influence of carbazole units and the introduction of electron‐donating on the electronic and optical properties. The electronic properties of the neutral molecules, HOMO‐LUMO gaps (ΔE), in addition to ionization potential (Ip) and electron affinity (Ea), are studied using B3LYP density functional theory. The lowest excitation energies (Eg) and the absorption wavelength are studied using the time dependent density functional theory (TDDFT). The calculated results show that all three series of polymers have good planarity. And the highest‐occupied molecular orbital (HOMO) energies lift about 0.36–0.61 eV and thus the IP decrease about 0.01–0.19 eV compared to polycarbazole, suggesting the significant improved hole‐accepting and transporting abilities. By introducing the electron‐donating 1,4‐divinylphenylene or 2,5‐divinylthiophene or 2,5‐divinylfuran units in the backbone, and the lowest‐unoccupied molecular orbital (LUMO) energies decrease 0.20–0.39 eV. In addition, PBC, PBT and PBF have longer maximal absorption wavelengths than polycarbazole. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 706–714, 2009
Evaluation at atomic resolution of the role of strain in destabilizing the temperature‐sensitive T4 lysozyme mutant Arg 96 → His
Authors: Mooers Blaine H. M. , Tronrud Dale E. , Matthews Brian W.
Published: February 2009

Mutant R96H is a classic temperature‐sensitive mutant of bacteriophage T4 lysozyme. It was in fact the first variant of the protein to be characterized structurally. Subsequently, it has been studied extensively by a variety of experimental and computational techniques, but the reasons for the loss of stability of the mutant protein remain controversial. In the crystallographic refinement of the mutant structure at 1.9 Å resolution one of the bond angles at the site of substitution appeared to be distorted by about 11°, and it was suggested that this steric strain was one of the major factors in destabilizing the mutant. Different computationally‐derived models of the mutant structure, however, did not show such distortion. To determine the geometry at the site of mutation more reliably, we have extended the resolution of the data and refined the wildtype (WT) and mutant structures to be better than 1.1 Å resolution. The high‐resolution refinement of the structure of R96H does not support the bond angle distortion seen in the 1.9 Å structure determination. At the same time, it does confirm other manifestations of strain seen previously including an unusual rotameric state for His96 with distorted hydrogen bonding. The rotamer strain has been estimated as about 0.8 kcal/mol, which is about 25% of the overall reduction in stability of the mutant. Because of concern that contacts from a neighboring molecule in the crystal might influence the geometry at the site of mutation we also constructed and analyzed supplemental mutant structures in which this crystal contact was eliminated. High‐resolution refinement shows that the crystal contacts have essentially no effect on the conformation of Arg96 in WT or on His96 in the R96H mutant.
Contributions of all 20 amino acids at site 96 to the stability and structure of T4 lysozyme
Authors: Mooers Blaine H. M. , Baase Walter A. , Wray Jonathan W. , Matthews Brian W.
Published: February 2009

To try to resolve the loss of stability in the temperature‐sensitive mutant of T4 lysozyme, Arg 96 → His, all of the remaining 18 naturally occurring amino acids were substituted at site 96. Also, in response to suggestions that the charged residues Lys85 and Asp89, which are 5–8 Å away, may have important effects, each of these amino acids was replaced with alanine. Crystal structures were determined for many of the variants. With the exception of the tryptophan and valine mutants R96W and R96V, the crystallographic analysis shows that the substituted side chain following the path of Arg96 in wildtype (WT). The melting temperatures of the variants decrease by up to ∼16°C with WT being most stable. There are two site 96 replacements, with lysine or glutamine, that leave the stability close to that of WT. The only element that the side chains of these residues have in common with the WT arginine is the set of three carbon atoms at the Cα, Cβ, and Cγ positions. Although each side chain is long and flexible with a polar group at the distal position, the details of the hydrogen bonding to the rest of the protein differ in each case. Also, the glutamine replacement lacks a positive charge. This shows that there is some adaptability in achieving full stabilization at this site. At the other extreme, to be maximally destabilizing a mutation at site 96 must not only eliminate favorable interactions but also introduce an unfavorable element such as steric strain or a hydrogen‐bonding group that remains unsatisfied. Overall, the study highlights the essential need for atomic resolution site‐specific structural information to understand and to predict the stability of mutant proteins. It can be very misleading to simply assume that conservative amino acid substitutions cause small changes in stability, whereas large stability changes are associated with nonconservative replacements.
Structural and functional modularity of proteins in the de novo purine biosynthetic pathway
Authors: Li Hui , Fast Walter , Benkovic Stephen J.
Published: February 2009

It is generally accepted that naturally existing functional domains can serve as building blocks for complex protein structures, and that novel functions can arise from assembly of different combinations of these functional domains. To inform our understanding of protein evolution and explore the modular nature of protein structure, two model enzymes were chosen for study, purT‐encoded glycinamide ribonucleotide formyltransferase (PurT) and purK‐encoded N5‐carboxylaminoimidazole ribonucleotide synthetase (PurK). Both enzymes are found in the de novo purine biosynthetic pathway of Escherichia coli. In spite of their low sequence identity, PurT and PurK share significant similarity in terms of tertiary structure, active site organization, and reaction mechanism. Their characteristic three domain structures categorize both PurT and PurK as members of the ATP‐grasp protein superfamily. In this study, we investigate the exchangeability of individual protein domains between these two enzymes and the in vivo and in vitro functional properties of the resulting hybrids. Six domain‐swapped hybrids were unable to catalyze full wild‐type reactions, but each hybrid protein could catalyze partial reactions. Notably, an additional loop replacement in one of the domain‐swapped hybrid proteins was able to restore near wild‐type PurK activity. Therefore, in this model system, domain‐swapped proteins retained the ability to catalyze partial reactions, but further modifications were required to efficiently couple the reaction intermediates and achieve catalysis of the full reaction. Implications for understanding the role of domain swapping in protein evolution are discussed.
Structural origin of weakly ordered nitroxide motion in spin‐labeled proteins
Authors: Fleissner Mark R. , Cascio Duilio , Hubbell Wayne L.
Published: February 2009

A disulfide‐linked nitroxide side chain (R1) used in site‐directed spin labeling of proteins often exhibits an EPR spectrum characteristic of a weakly ordered z‐axis anisotropic motion at topographically diverse surface sites, including those on helices, loops and edge strands of β‐sheets. To elucidate the origin of this motion, the first crystal structures of R1 that display simple z‐axis anisotropic motion at solvent‐exposed helical sites (131 and 151) and a loop site (82) in T4 lysozyme have been determined. Structures of 131R1 and 151R1 determined at cryogenic or ambient temperature reveal an intraresidue CαH···Sδ interaction that immobilizes the disulfide group, consistent with a model in which the internal motions of R1 are dominated by rotations about the two terminal bonds (Columbus, Kálai, Jeko, Hideg, and Hubbell, Biochemistry 2001;40:3828–3846). Remarkably, the 131R1 side chain populates two rotamers equally, but the EPR spectrum reflects a single dominant dynamic population, showing that the two rotamers have similar internal motion determined by the common disulfide‐backbone interaction. The anisotropic motion for loop residue 82R1 is also accounted for by a common disulfide‐backbone interaction, showing that the interaction does not require a specific secondary structure. If the above observations prove to be general, then significant variations in order and rate for R1 at noninteracting solvent‐exposed helical and loop sites can be assigned to backbone motion because the internal motion is essentially constant.
Migrant visions of development: a gendered approach
Authors: Dannecker Petra
Published: February 2009

In this article the current debate on migration and development is critically discussed. It will be shown that development as a multidimensional process is hardly ever conceptualised. The diversity of migration flows and patterns and the gendered structure of these processes are leading to different development visions which are hardly ever addressed or related to development. The analysis of the development visions of temporary male and female labour migrants from Bangladesh will reveal that migration experiences and the new connections and networks give rise to new identifications and development visions. The negotiations of these visions locally may initiate cultural, social and political transformations in the countries of origin, which do not necessarily correspond with the development visions articulated by other national and international actors involved. Copyright © 2009 John Wiley & Sons, Ltd.
Which migration, what development? Unsettling the edifice of migration and development
Authors: Raghuram Parvati
Published: February 2009

In recent years migration has been rediscovered as a key intervening apparatus in facilitating development, offering a route to mitigating deepening inequalities. National governments, international funding organisations and diasporic organisations have all mobilised migrants to fund development initiatives in ‘origin’ countries. This has led to a range of calculative processes whereby some forms of migration and particular forms of development come to be visible, while others become ‘invisibilised’. This paper explores some narratives of migration and development to illustrate how current debates on migration and development ignore certain scalar politics and specific temporalities, while scaffolding others. It suggests new ways of thinking about migration and development. Copyright © 2009 John Wiley & Sons, Ltd.
Temporary migration and changing family dynamics: implications for social development
Authors: Rahman Mizanur
Published: February 2009

Drawing upon longitudinal data, this research documents the relationship between migration and development by highlighting the conditions which promote changes in social and familial relations, social positioning, and intergenerational relationships within the families who experience temporary out‐migration and the return of at least one male member. The fieldwork data (based on two surveys) derive from research conducted on Bangladeshi temporary migrants in Singapore and in an ‘origin’ village in Bangladesh in 2001 and 2006. The study reports that male labour migration has contributed to social changes in their own families and villages over time that are most likely to stimulate, in turn, macro‐changes in Bangladeshi society in the long run. Copyright © 2009 John Wiley & Sons, Ltd.
Foreigners in our homes: linking migration and family policies in Singapore
Authors: Teo Youyenn , Piper Nicola
Published: February 2009

In Singapore, despite high levels of state intervention in managing the influx of foreign labour, work conditions of foreign domestic workers (FDWs) are largely left to the discretion of individual employers. We argue that to better understand the government's reticence, as well as certain reluctance on the part of employers for reform on this particular issue, we need to go beyond the analysis of migration policies. Policies towards FDWs must be situated in the context of other social policies targeted at the citizens of Singapore. We show that the reform of migrant workers' working and living conditions and the limits to the reform depend on what these reforms mean in the context of the state's approach to welfare, and particularly its idealised vision of ‘the Singapore family’ within this framework. Copyright © 2009 John Wiley & Sons, Ltd.
Production for export: the role of the state in the development and operation of global care chains
Authors: Yeates Nicola
Published: February 2009

In its focus on different forms of public and private agency within the global (care) economy, global care chains (GCC) analysis has tended to neglect the role of the state in the development of GCCs. Through a focus on GCCs involving nurses – global nursing care chains (GNCCs) – this article aims to contribute to bridging that analytical deficit. It argues that state strategies to develop an export industry in healthcare labour constitute a major input into the formation and operation of GNCCs. Proceeding through a review of state export‐oriented production strategies across Asia, it explores key aspects of states' emphasis on nurse labour export as an economic development strategy, and demonstrates the importance of the state in three main ways: firstly, through the management and promotion of female migration; secondly, through the development of nurse education involving public‐private partnerships, and thirdly, through a concern to ensure the ‘product quality’ of the nursing labour it exports. In promoting the export of nurses, Asian states are not only prioritising dubious economic development policies over national health development policies, but they are also implicitly prioritising the health systems of foreign countries over their own health systems and their population's health. Copyright © 2009 John Wiley & Sons, Ltd.
A Lattice‐Boltzmann model to simulate the growth of dendritic and eutectic microstructures under the influence of fluid flow
Authors: Selzer Michael , Jainta Marcus , Nestler Britta
Published: February 2009

We present a new formulation of a composite phase‐field and Lattice‐Boltzmann model to analyze the effect of fluid flow on the formation of solidification microstructures. The phase‐field model is based on a description suitable to treat phase tansformation processes and moving boundary problems in multiphase and multicomponent systems as well as in polycrystalline structures. The flow of the liquid is simulated by a Lattice‐Boltzmann‐BGK (LBGK) method. Interactions of the flow field with thermal and solutal convection are incorporated by additional advection terms in the mass and heat diffusion equations. At the boundaries between solid and liquid phases, the flow is modelled by a diffuse bounce back approach.

In two‐ and three‐dimensional numerical simulations, we apply the model to investigate flow driven changes of the dendritic morphology in the Ni–Cu system. In particular, we impose different flow velocities at the boundary of the computational domain and investigate the different growth rates of the dendritic tip towards the direction of flow and on the shielded side. Furthermore, the influence of a fluid field on lamellar and rod‐like eutectic growth structures is studied for Al–Cu alloys. Since new solute is supplied by the fluid, a more pronounced growth is observed in the direction of the flow for both cases, dendrites and eutectics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First principles calculations of Al‐rich RE (RE = Ho, Er, Tm and Yb) intermetallic compounds
Authors: Srivastava Vipul , Pagare Gitanjali , Sanyal Sankar P. , Rajagopalan M.
Published: February 2009

The electronic structure of nonmagnetic intermetallic AlRE (RE = Ho, Er, Tm and Yb) compounds, which crystallize in the CsCl‐type (B2) structure, is studied by means of the self‐consistent tight binding linear muffin tin orbital method at ambient as well as at high pressure. The total energies are computed as a function of volume and fitted to the Birch equation of state. The ground‐state properties such as the equilibrium lattice parameter, the bulk modulus and the cohesive properties of these compounds are calculated. Interestingly, in AlTm and AlYb, f‐like electrons may get delocalized and show fluctuations in the total density of states. Thermal properties like Debye temperature and Grüneisen constants are estimated within the Debye–Grüneisen model. The results obtained are compared with the available experimental values and other theoretical results. We find good agreement between theory and experiment. The variation of Debye temperature with pressure is also studied. We also present electronic charge density plots to reveal bonding properties in the intermetallics under investigation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the local molecular structure of metal perchlorate complex from the electron paramagnetic resonance spectra for a substitution of Mn2+ ion: a complete energy matrices study
Authors: Ya‐Ru Zhao , Ming‐Liang Gao , Yan‐Fang Li , Cheng Lu , Xiao‐Yu Kuang
Published: February 2009

A simple theoretical method is introduced for studying the local molecular structure of the (MnO6)10– coordination complex. By diagonalizing the complete energy matrices of the electron–electron repulsion, the ligand field and the spin–orbit coupling for a d5 configuration ion in a trigonal ligand field, the local distortion structure of the (MnO6)10– coordination complex for Mn2+ ions in A–PCC:Mn2+ (PCC = {[(CH3)2N]2OPOPO[N(CH3)2]2}(ClO4)2, A = Mg, Zn) complex systems is investigated. Both the second‐order zero‐field splitting parameter b20 and the fourth‐order zero‐field splitting parameter b40 are taken simultaneously in the structural investigation. From electron paramagnetic resonance (EPR) calculations, the local structure parameters R = 2.18 Å, θ = 56.38° for Mn2+ ions in Mg–PCC:Mn2+ and R = 2.20 Å, θ = 56.52° for Mn2+ ions in Zn–PCC:Mn2+ complex systems are determined, respectively. It is found that the theoretical calculation results of the EPR spectra for Mn2+ ions in A–PCC:Mn2+ complex systems are in good agreement with the experimental values. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles study of NaCdF3
Authors: Akkus Harun , Erdinc Bahattin
Published: February 2009

The electronic structure, density of states and linear optical properties of NaCdF3 are studied using density functional methods in the local density approximation (LDA) and the generalized gradient approximation (GGA). The calculated band structure of NaCdF3 shows a direct band gap at the Γ‐point in the Brillouin zone. The structural optimization of NaCdF3 is performed using the LDA and the GGA. The calculated structural optimization of NaCdF3 is compared with previous results and is found to be in good agreement with those results. The optical spectra of NaCdF3 in the photon energy range up to 30 eV are investigated under the scissor approximation. The real and imaginary parts of the dielectric function as a function of the photon energy and hence optical constants such as refractive index, energy loss for volume and surface, extinction coefficient, reflectivity and absorption coefficient have been calculated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monitoring dependent process steps using robust cause‐selecting control charts
Authors: Asadzadeh Shervin , Aghaie Abdollah , Shahriari Hamid
Published: February 2009

Cause‐selecting control charts are believed to be invaluable for monitoring and diagnosing multistage processes where the output quality of some stages is significantly impacted by the output quality of preceding stages. To establish a relationship between input and output variables, a standard procedure uses historical data, which are often prone to hold outliers. The presence of outliers tends to decrease the effectiveness of monitoring procedures because the regression model is distorted and the control limits become stretched. To dampen the negative repercussions of outliers, robust fitting techniques based on M‐estimators are implemented instead of the ordinary least‐squares method and two robust monitoring approaches are presented. An example is given to illustrate the application and performance of the proposed control charts. Furthermore, a simulation‐based study is included to investigate and compare the average run length of robust and non‐robust schemes. The results reveal that the robust procedure far outperforms the non‐robust counterpart due to its prompt detection of out‐of‐control conditions when outliers exist. Copyright © 2009 John Wiley & Sons, Ltd.
Global planning on the Mars Exploration Rovers: Software integration and surface testing
Authors: Carsten Joseph , Rankin Arturo , Ferguson Dave , Stentz Anthony
Published: February 2009

In January 2004, NASA's twin Mars Exploration Rovers (MERs), Spirit and Opportunity, began searching the surface of Mars for evidence of past water activity. To localize and approach scientifically interesting targets, the rovers employ an onboard navigation system. Given the latency in sending commands from Earth to the Martian rovers (and in receiving return data), a high level of navigational autonomy is desirable. Autonomous navigation with hazard avoidance (AutoNav) is currently performed using a local path planner called GESTALT (grid‐based estimation of surface traversability applied to local terrain) that incorporates terrain and obstacle information generated from stereo cameras. GESTALT works well at guiding the rovers around narrow and isolated hazards; however, it is susceptible to failure when clusters of closely spaced, nontraversable rocks form extended obstacles. In May 2005, a new technology task was initiated at the Jet Propulsion Laboratory to address this limitation. Specifically, a version of the Field D* global path planner was integrated into MER flight software, enabling simultaneous local and global planning during AutoNav. A revised version of AutoNav was then uploaded to the rovers during the summer of 2006. In this paper we describe how this integration of global planning into the MER flight software was performed and provide results from both the MER surface system test bed rover and five fully autonomous runs by Opportunity on Mars. © 2009 Wiley Periodicals, Inc.
Toward extraplanetary under‐ice exploration: Robotic steps in the Arctic
Authors: Kunz Clayton , Murphy Chris , Singh Hanumant , Pontbriand Claire , Sohn Robert A. , Singh Sandipa , Sato Taichi , Roman Chris , Nakamura Ko‐ichi , Jakuba Michael , Eustice Ryan , Camilli Richard , Bailey John
Published: February 2009

This paper describes the design and use of two new autonomous underwater vehicles, Jaguar and Puma, which were deployed in the summer of 2007 at sites at 85°N latitude in the ice‐covered Arctic Ocean to search for hydrothermal vents. These robots are the first to be deployed and recovered through ice to the deep ocean (>3,500 m) for scientific research. We examine the mechanical design, software architecture, navigation considerations, sensor suite, and issues with deployment and recovery in the ice based on the missions they carried out. Successful recoveries of vehicles deployed under the ice require two‐way acoustic communication, flexible navigation strategies, redundant localization hardware, and software that can cope with several different kinds of failure. The ability to direct an autonomous underwater vehicle via the low‐bandwidth and intermittently functional acoustic channel is of particular importance. On the basis of our experiences, we also discuss the applicability of the technology and operational approaches of this expedition to the exploration of Jupiter's ice‐covered moon Europa. © 2009 Wiley Periodicals, Inc.
Quantifying the source of infection for HIV‐infected hemophiliacs in the U.K. from 1979 to 1984
Authors: Jewell Nicholas P.
Published: February 2009

There is considerable literature on the risk of HIV infection for individuals suffering from hemophilia A in the United Kingdom (U.K.) during the period 1979–1984 when the sources of Factor VIII clotting factor were contaminated with HIV. Toward the end of this period, several investigators reported HIV prevalence among hemophiliacs, often classified by the severity of disease and, to some extent, the source of the clotting factor with which individuals were infused. In the U.K., hemophilia A patients typically received clotting factor from the local National Health Service (NHS) supplies or from commercial product usually imported from the United States. Litigation on behalf of U.K. hemophiliacs, their survivors, and estates remains unresolved, cases in which it becomes important to quantify the fraction of U.K. hemophiliac HIV infections attributable to imported blood product. For HIV‐infected individuals who received Factor VIII from one source exclusively, the source of infection is clear, assuming no other risk factors. For patients who used both types of clotting factor, the source of infection is uncertain. For the U.K. as a whole, we produce quantitative estimates of the conditional probability of infection due to a specific source, based on HIV prevalence in groups exclusively exposed to a specific source and the percentage of clotting factor that was imported. With plausible estimates of these input parameters, an estimate of the conditional probability of infection due to imported product is 0.93 (95 per cent CI: 0.90–0.96). This estimate is relatively insensitive to changes in input parameters, but may vary over subgroups of hemophiliacs. Copyright © 2009 John Wiley & Sons, Ltd.
Sensitivity analysis to investigate the impact of a missing covariate on survival analyses using cancer registry data
Authors: Egleston Brian L. , Wong Yu‐Ning
Published: February 2009

Having substantial missing data is a common problem in administrative and cancer registry data. We propose a sensitivity analysis to evaluate the impact of a covariate that is potentially missing not at random in survival analyses using Weibull proportional hazards regressions. We apply the method to an investigation of the impact of missing grade on post‐surgical mortality outcomes in individuals with metastatic kidney cancer. Data came from the Surveillance Epidemiology and End Results (SEER) registry which provides population‐based information on those undergoing cytoreductive nephrectomy. Tumor grade is an important component of risk stratification for patients with both localized and metastatic kidney cancer. Many individuals in SEER with metastatic kidney cancer are missing tumor grade information. We found that surgery was protective, but that the magnitude of the effect depended on assumptions about the relationship of grade with missingness. Copyright © 2009 John Wiley & Sons, Ltd.
Persons with AIDS and their support persons: stress and life satisfaction
Authors: Darling Carol Anderson , Olmstead Spencer B. , Tiggleman Cornelius
Published: February 2009

The purpose of this study was to investigate the role of historical family functioning, family stress, coping, perceived impact of acquired immune deficiency syndrome (AIDS), and health stress upon the life satisfaction of persons with AIDS (PWAs) and their support persons. Utilizing Family Stress Theory, a survey research design was employed involving 114 PWAs and 114 support persons. Historical family functioning was indirectly related to life satisfaction as mediated by family coping. Current family stress was indirectly related to life satisfaction as mediated by perception of stress. Female support persons experienced greater perceptions of caregiver stress. Family and health‐care professionals need to be aware of the importance of family stress and coping as they influence the health stress and life satisfaction of PWAs and their support persons. Copyright © 2009 John Wiley & Sons, Ltd.
Elasticity Mapping of Pore‐Suspending Native Cell Membranes
Authors: Lorenz Bärbel , Mey Ingo , Steltenkamp Siegfried , Fine Tamir , Rommel Christina , Müller Martin Michael , Maiwald Alexander , Wegener Joachim , Steinem Claudia , Janshoff Andreas
Published: February 2009

The mechanics of cellular membranes are governed by a non‐equilibrium composite framework consisting of the semiflexible filamentous cytoskeleton and extracellular matrix proteins linked to the lipid bilayer. While elasticity information of plasma membranes has mainly been obtained from whole cell analysis, techniques that allow addressing local mechanical properties of cell membranes are desirable to learn how their lipid and protein composition is reflected in the elastic behavior on local length scales. Introduced here is an approach based on basolateral membranes of polar epithelial Madin–Darby canine kidney (MDCK) II cells, prepared on a highly ordered porous substrate that allows elastic mapping on a submicrometer‐length scale. A strong correlation between the density of actin filaments and the measured membrane elasticity is found. Spatially resolved indentation experiments carried out with atomic force and fluorescence microscope permit relation of the supramolecular structure to the elasticity of cellular membranes. It is shown that the elastic response of the pore spanning cell membranes is governed by local bending modules rather than lateral tension.
Advancements Toward the Greener Processing of Engineered Nanomaterials—Effect of Core Size on the Dispersibility and Transport of Gold Nanocrystals in Near‐Critical Solvents
Authors: Fernandez Carlos A. , Bekhazi Jacky G. , Hoppes Emily M. , Wiacek Robert J. , Fryxell Glen E. , Bays J. Timothy , Warner Marvin G. , Wang Chongmin , Hutchison James E. , Addleman R. Shane
Published: February 2009

The ability to process and purify engineered nanomaterials using near critical or supercritical fluids (NcFs or ScFs) has enormous potential for the application at various stages of the development of green nanomaterials. The dispersibility of octanethiol‐stabilized gold nanocrystals of different core sizes is explored, which were chosen to serve as model nanomaterials of general interest in compressed ethane and propane over a wide range of fluid conditions. Both solvents have enormous potential for the environmentally benign processing and transport of engineered nanomaterials due to their nominal toxicity and high degree of tunability and processability that can essentially eliminate solvent waste. The dispersibility is determined by measuring the absorption spectra of dispersions of various sizes of nanocrystals in NcFs. To better understand the obtained results three models, the total interaction theory, the sedimentation coefficient equation, and the Chrastil method, are discussed. Nanoparticle dispersibility versus density plots are strongly dependent on nanoparticle size and solvent conditions, with the dispersion of larger nanocrystals more dependent on changes of pressure or density at a given temperature. For the range of nanoparticle sizes studied, compressed ethane at 25 °C leads to a greater tunability of nanoparticle dispersion when compared with compressed propane at 65 °C. For equivalent pressures, compressed propane is found to provide better solubility than ethane due to its higher density. The results quantitatively demonstrate that NcFs can offer pressure‐tunable, size‐selective control of nanoparticle solvation and transport at easily obtainable temperature and pressure conditions. These capabilities provide clear advantages over conventional solvents and direct application to various nanomaterials processes, such as synthesis, separation, transport, and purification of nanocrystals.
Simultaneous Fabrication of Very High Aspect Ratio Positive Nano‐ to Milliscale Structures
Authors: Chen Long Qing , Chan‐Park Mary B. , Zhang Qing , Chen Peng , Li Chang Ming , Li Sai
Published: February 2009

A simple and inexpensive technique for the simultaneous fabrication of positive (i.e., protruding), very high aspect (>10) ratio nanostructures together with micro‐ or millistructures is developed. The method involves using residual patterns of thin‐film over‐etching (RPTO) to produce sub‐micro‐/nanoscale features. The residual thin‐film nanopattern is used as an etching mask for Si deep reactive ion etching. The etched Si structures are further reduced in size by Si thermal oxidation to produce amorphous SiO2, which is subsequently etched away by HF. Two arrays of positive Si nanowalls are demonstrated with this combined RPTO‐SiO2‐HF technique. One array has a feature size of 150 nm and an aspect ratio of 26.7 and another has a feature size of 50 nm and an aspect ratio of 15. No other parallel reduction technique can achieve such a very high aspect ratio for 50‐nm‐wide nanowalls. As a demonstration of the technique to simultaneously achieve nano‐ and milliscale features, a simple Si nanofluidic master mold with positive features with dimensions varying continuously from 1 mm to 200 nm and a highest aspect ratio of 6.75 is fabricated; the narrow 200‐nm section is 4.5 mm long. This Si master mold is then used as a mold for UV embossing. The embossed open channels are then closed by a cover with glue bonding. A high aspect ratio is necessary to produce unblocked closed channels after the cover bonding process of the nanofluidic chip. The combined method of RPTO, Si thermal oxidation, and HF etching can be used to make complex nanofluidic systems and nano‐/micro‐/millistructures for diverse applications.
Site‐Controlled InGaAs Quantum Dots with Tunable Emission Energy
Authors: Felici Marco , Gallo Pascal , Mohan Arun , Dwir Benjamin , Rudra Alok , Kapon Eli
Published: February 2009

Semiconductor quantum‐dot (QD) systems offering perfect site control and tunable emission energy are essential for numerous nanophotonic device applications involving spatial and spectral matching of dots with optical cavities. Herein, the properties of ordered InGaAs/GaAs QDs grown by organometallic chemical vapor deposition on substrates patterned with pyramidal recesses are reported. The seeded growth of a single QD inside each pyramid results in near‐perfect (<10 nm) control of the QD position. Moreover, efficient and uniform photoluminescence (inhomogeneous broadening <10 meV) is observed from ordered arrays of such dots. The QD emission energy can be finely tuned by varying 1) the pyramid size and 2) its position within specific patterns. This tunability is brought about by the patterning of both the chemical properties and the surface curvature features of the substrate, which allows local control of the adatom fluxes that determine the QD thickness and composition.
Dual‐Functional Alginic Acid Hybrid Nanospheres for Cell Imaging and Drug Delivery
Authors: Guo Rui , Li Rutian , Li Xiaolin , Zhang Leyang , Jiang Xiqun , Liu Baorui
Published: February 2009

An effective and facile approach to prepare gold‐nanoparticle‐encapsulated alginic acid‐poly[2‐(diethylamino)ethyl methacrylate] monodisperse hybrid nanospheres (ALG–PDEA–Au) is developed by using monodisperse ALG–PDEA nanospheres as a precursor nanoparticulate reaction system. This approach utilizes particle‐interior chemistry, which avoids additional reductant or laborious separation process and, moreover, elegantly ensures that all the gold nanoparticles are located inside the hybrid nanospheres and every nanosphere is loaded with gold nanoparticles. These obtained ALG–PDEA–Au hybrid nanospheres have not only uniform size, similar surface properties, and good biocompatibility but also unique optical properties provided by the embedded gold nanoparticles. It is demonstrated that negatively charged ALG–PDEA–Au hybrid nanospheres can be internalized by human colorectal LoVo cancer cells and hence act as novel optical‐contrast reagents in tumor‐cell imaging by optical microscopy. Moreover, these hybrid nanospheres can also serve as biocompatible carriers for the loading and delivery of an anti‐cancer drug doxorubicin. In vitro cell viability tests reveal that drug‐loaded ALG–PDEA–Au hybrid nanospheres exhibit similar tumor cell inhibition to the free drug doxorubicin. Therefore, the obtained hybrid nanospheres successfully combine two functions, that is, cell imaging and drug delivery, into one single system, and may be of great application potential in other biomedical‐related areas.
Conceiving methods and innovative approaches for tall building structure systems
Authors: Shi Jianguang , Han Tong
Published: February 2009

Conceiving tall building structure systems is a major step in the plan and design of tall buildings. Through summarizing the basic components and the basic lateral elements in various tall building structures, four conceiving methods for tall building structure systems are presented: (1) intercombination or alone forming by the basic lateral elements, (2) intercombination of different structures, (3) adding basic components in structure systems and (4) replacing basic components in structure systems. With these methods, designers could be able to establish the needed structure system to meet architectural functions, spatial arrangement, facade and other conditions, and these conceiving methods are helpful to architects or engineers to innovate the structure system in their special project. Copyright © 2009 John Wiley & Sons, Ltd.
A nonlinear model to rank association rules based on semantic similarity and genetic network programing
Authors: Yang Guangfei , Shimada Kaoru , Mabu Shingo , Hirasawa Kotaro
Published: February 2009

Many methods have been studied for mining association rules efficiently. However, because these methods usually generate a large number of rules, it is still a heavy burden for the users to find the most interesting ones. In this paper, we propose a novel method for finding what the user is interested in by assigning several keywords, like searching documents on the Web using search engines. By considering both the semantic similarity between the rules and keywords, and the statistical information like support, confidence, chi‐squared value, etc. we could rank the rules by a new method named RuleRank, where evolutionary methods are applied to find the optimal ranking model. Experiments show that our approach is effective for the users to find what they want. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Haptic motion control for physical human support
Authors: Shimono Tomoyuki , Katsura Seiichiro , Ohnishi Kouhei
Published: February 2009

Future robots and mechatronic systems will be required to physically support human activities. In order to reach the stage of real human‐friendly physical support, they should acquire many functions such as the recognition of the real world based on complicated human actions, the transmission of the ambient information in harmony with human sensation, and so on. Since haptic sensation, as well as visual information and auditory sensation are so important for human activities, haptic motion control is one of the most important issues for the purpose. This paper now presents some haptic motion control techniques as the fundamental technology for the realization of future physical human support. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Management of transgender problems
Authors: Levy Andy
Published: February 2009

Gender identity disorder is an incurable condition associated with social discrimination and a high risk of substance abuse, mental disorder and suicide. The author discusses the surgical and hormonal treatments available for transsexual people and makes it clear that these must be tailored to the individual. Copyright © 2009 Wiley Interface Ltd
Bladder mass detected during early pregnancy
Authors: Sharma Davendra M. , Butt Aurangzeb , Saleemi Asad , Chitale Sudhanshu
Published: February 2009

The authors describe a case history of a pregnant woman who presented with brown vaginal discharge at eight weeks' gestation and was found to have a bladder lesion. The case highlights the importance of an early accurate diagnosis and a cautious, multidisciplinary approach to management. Copyright © 2009 Wiley Interface Ltd
An energy‐efficient transmission mechanism for VoIP over IEEE 802.11 WLAN
Authors: Tsao Shiao‐Li , Huang Chung‐Huei
Published: February 2009

Voice over IP (VoIP) over WLAN (VoWLAN) is an important application for public and private WLANs. However, VoWLAN systems suffer from several technical challenges such as power consumption of a WLAN station (STA) and service capacity of an access point (AP), making the commercial deployment of a large‐scale VoWLAN service problematic. This study presents a cross‐layer and energy‐efficient mechanism for transmitting VoIP packets over IEEE 802.11 WLAN. The proposed mechanism considers the characteristics of voice packets that can tolerate certain loss, and dynamically disables the medium access control (MAC) layer acknowledgement for voice packets. In doing so, the time and energy consumed to transmit and receive voice packets for an STA can be reduced. Simulation results demonstrate that the mechanism improves the energy efficiency of a VoWLAN STA and WLAN utilization without sacrificing voice qualities. Copyright © 2009 John Wiley & Sons, Ltd.
Rsf1p is required for an efficient metabolic shift from fermentative to glycerol‐based respiratory growth in S. cerevisiae
Authors: Roberts III George G. , Hudson Alan P.
Published: February 2009

Previous studies from this laboratory indicated that the product of the RSF1 gene of S. cerevisiae is present in both nucleus and mitochondria, and they suggested that Rsf1p acts as a transcriptional modulator. To investigate this latter question, we performed transcriptome profiling of an rsf1 mutant strain and its wild‐type parent during a shift from glucose‐based fermentative to glycerol‐based respiratory growth to identify genes whose expression is regulated by Rsf1p. Loss of Rsf1p engendered a decrease in transcript levels from many genes encoding components of the electron transport chain and various other mitochondrially‐localized products. The earlier studies further showed that rsf1 cells exhibit a growth defect on medium containing glycerol, but not ethanol, as sole carbon source. Importantly, transcriptome profiling of the rsf1 mutant during shift from glucose‐ to glycerol‐based medium revealed that the product of this gene plays a major role in both orchestration of the transition to, and maintenance of, efficient growth on glycerol as sole carbon source. An increase in transcript levels from genes encoding products that function in the stress response, and an imbalance between expression of genes encoding glycerol anabolic and catabolic enzymes, was observed in the rsf1 mutant during steady‐state growth on glycerol‐ but not ethanol‐based medium; this suggests the presence of partially separate transcriptional regulatory systems for transition to respiratory growth on each of these two carbon sources. Genes whose expression is affected by loss of Rsf1p, which lacks a known DNA‐binding motif, lack a common DNA sequence motif in their upstream regions. These and other data presented here strongly suggest that the transcriptional effects exerted by Rsf1p are mediated via interaction with other transcription factors. Copyright © 2009 John Wiley & Sons, Ltd.