bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of putative Japanese encephalitis virus receptor molecules on microglial cells
Authors: Thongtan Thananya , Wikan Nitwara , Wintachai Phitchayapak , Rattanarungsan Chutima , Srisomsap Chantragan , Cheepsunthorn Poonlarp , Smith Duncan R.
Published: February 2012

Japanese encephalitis virus (JEV) a mosquito‐borne flavivirus is a major cause of viral encephalitis in Asia. While the principle target cells for JEV in the central nervous system are believed to be neurons, microglia are activated in response to JEV and have been proposed to act as a long lasting virus reservoir. Viral attachment to a host cell is the first step of the viral entry process and is a critical mediator of tissue tropism. This study sought to identify molecules associated with JEV entry to microglial cells. Virus overlay protein‐binding assay (VOPBA) and liquid chromatography–mass spectrometry (LC/MS/MS) identified the 37/67 kDa high‐affinity laminin receptor protein and nucleolin as a potential JEV‐binding proteins. These proteins were subsequently investigated for a contribution to JEV entry to mouse microglial BV‐2 cells together with other possible candidate receptor molecules including Hsp70, Hsp90, GRP78, CD14, and CD4. In antibody mediated inhibition of infection experiments, both anti‐laminin receptor and anti‐CD4 antibodies significantly reduced virus entry while anti‐Hsp70 and 90 antibodies produced a slight reduction. Significant inhibition of virus entry (up to 80%) was observed in the presence of lipopolysaccharide (LPS) which resulted in a complete down‐regulation of CD4 and moderate down‐regulation of CD14. These results suggest that multiple receptor proteins may mediate the entry of JEV to microglial cells, with CD4 playing a major role. J. Med. Virol. 84:615–623, 2012. © 2011 Wiley Periodicals, Inc.
Amine‐surface‐modified superparamagnetic iron oxide nanoparticles interfere with differentiation of human mesenchymal stem cells
Authors: Chang You‐Kang , Liu Yu‐Peng , Ho Jennifer H. , Hsu Shu‐Ching , Lee Oscar K.
Published: February 2012

Superparamagnetic iron oxide (SPIO) nanoparticles have been widely used for stem cell labeling and tracking. Surface modification has been known to improve biocompatibility, biodistribution, and labeling efficiency of SPIO nanoparticles. However, the effects of amine (NH)‐surface‐modified SPIO nanoparticles on proliferation and differentiation of human mesenchymal stem cells (hMSCs) remain unclear. The purpose of this study is to investigate how amine‐surface‐modified SPIO nanoparticles affected hMSCs. In this study, intracellular uptake and the contiguous presence of amine‐surface‐modified SPIO nanoparticles in hMSCs were demonstrated by Prussian blue staining, transmission electron microscopy and magnetic resonance imaging. Moreover, accelerated cell proliferation was found to be associated with cellular internalization of amine‐surface‐modified SPIO nanoparticles. The osteogenic and chondrogenic differentiation potentials of hMSCs were impaired after treating with SPIO, while adipogenic potential was relatively unaffected. Altered cytokine production profile in hMSCs caused by amine‐surface‐modified SPIO nanoparticles may account for the increased proliferation and impaired differentiation potentials; concentrations of the growth factors in the SPIO‐labeled condition medium including amphiregulin, glial cell‐derived neurotrophic factor, heparin‐binding EGF‐like growth factor and vascular endothelial growth factor, as well as soluble form of macrophage colony‐stimulating factor receptor and SCF receptor, were higher than in the unlabeled‐condition medium. In summary, although amine‐surface‐modified SPIO labeling is effective for cell tracking, properties of hMSCs may alter as a consequence and this needs to be taken into account when evaluating therapeutic efficacies of SPIO‐labeled stem cells in vivo. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1499–1506, 2012
Reproduction in a population of wild pigs (Sus scrofa) subjected to lethal control
Authors: Ditchkoff Stephen S. , Jolley D. Buck , Sparklin Bill D. , Hanson Laura B. , Mitchell Michael S. , Grand James B.
Published: February 2012

The continued range expansion of wild pigs (Sus scrofa) in North America is an increasing cause for concern because of the numerous negative impacts that wild pigs have on ecosystem structure and function. Once populations are established, wild pigs have proven to be extremely difficult to control, and close to impossible to eradicate. If effective control and removal techniques are to be developed, we must determine if wild pig populations respond to reductions in density by increasing reproductive output. This study was designed to examine if reproductive parameters of female wild pigs display a density‐dependent response following a concentrated removal effort. We compared reproductive parameters and condition of adult sows that were collected between a control area and a treatment area where lethal removal occurred. From August 2004 to May 2006, we focused a concentrated removal effort within the treatment area. Although the population density was more than 65% greater in the control area than the treatment area during the study, we did not detect differences between areas for condition, litter size, ovarian mass, corpus luteum mass, or corpora lutea number. Several years of heavy mast production during the study may have negated any effect on condition and subsequent reproduction between the 2 study areas. These data suggest that reproductive parameters of wild pigs do not exhibit density‐dependence during periods when pig populations are in good condition. © 2012 The Wildlife Society.
Functional Polymers Bearing Reactive Azetidinium Groups: Synthesis and Characterization
Authors: Chattopadhyay Subrata , Keul Helmut , Moeller Martin
Published: February 2012

Functional polymers with azetidinium groups in the backbone are synthesized via the reaction of aminotelechelic polymers, containing primary and secondary amino groups, with epichlorohydrin. During the reaction, the secondary amino groups are transformed into azetidinium groups and the primary amino groups are transformed into amino‐chlorohydrin, amino‐epoxide, and azetidinium groups. The formation of desired functional groups in the polymer is controlled by tuning the reaction conditions. To understand the influence of reaction conditions generating the desired functional groups, model reactions of primary and secondary amines with epichlorohydrin are studied in detail, including the influence of the mole ratio of the starting materials, effect of solvent, effect of pH, and reaction kinetics.
Computation of H ∞  controllers for infinite dimensional plants using numerical linear algebra
Authors: Özbay H.
Published: February 2012

The mixed sensitivity minimization problem is revisited for a class of single‐input‐single‐output unstable infinite dimensional plants with low order weights. It is shown that H ∞  controllers can be computed from the singularity conditions of a parameterized matrix whose dimension is the same as the order of the sensitivity weight. The result is applied to the design of H ∞  controllers with integral action. Connections with the so‐called Hamiltonian approach are also established. Copyright © 2012 John Wiley & Sons, Ltd.
Mode superposition with submodeling
Authors: Jakobsson Håkan , Larson Mats G.
Published: February 2012

We investigate a new approach for local enhancement of mode superpositions, which builds on the concept of submodeling. To this end, we impose a multiscale split on the reduced solution into a global part defined by the mode superposition method and a local part defined by a patch problem solved in a subspace of the finite element space associated with a subdomain around some region of interest. The patch problem yields a local correction on the modal approximation. We describe the basics of this approach and evaluate the accuracy of the approximation in elastostatic numerical examples. We also demonstrate how the submodeling technique may be applied as a post‐processing operation on a set of reduced solutions, for example, from dynamics simulation, to enhance accuracy in some domain of interest. Copyright © 2012 John Wiley & Sons, Ltd.
Self‐medication with antibiotics in the Republic of Srpska community pharmacies: pharmacy staff behavior
Authors: Marković‐Peković Vanda , Grubiša Nataša
Published: February 2012

Purpose

Self‐medication with antibiotics adds to the global risk of increased spread of bacterial resistance. Attitudes and behavior of health professionals also may reinforce self‐medication with antibiotics. The aim of this study was to determine whether self‐medication with antibiotics is possible in our community pharmacies and to what extent, and to evaluate the behavior and service of pharmacy health professionals regarding non‐prescription antibiotic dispensation.

Methods

An observational, cross‐section study was conducted, and pseudo‐patient methodology was used to establish the kind of professional service provided in case of patient's explicit demand to buy an antibiotic for treatment of self‐diagnosed upper respiratory tract infection.

Results

Of the total 318 community pharmacies, 131 (41%) were visited and included in the study. Non‐prescription antibiotics were dispensed in 76 (58%) pharmacies. Counseling and symptomatic therapy was offered in 88 (67%) pharmacies. In 25% of pharmacies, no symptomatic therapy was offered; instead, only an antibiotic was sold. Amoxicillin was sold in 85% of cases and, mostly, the one of 1.30 Euro per pack. Both oral and written use instructions were given in 78% cases, whereas none was given in 3% of cases.

Conclusions

Self‐medication with antibiotics occurs in our community pharmacies, despite being illegal. Pharmacy staff behavior can be a factor that puts patients at risk for self‐medication with antibiotics. Community pharmacies are failing their tasks in enhancing rational use of antibiotics. Such a practice may be a consequence of weak enforcement and control over the legislation and professional standards. Copyright © 2012 John Wiley & Sons, Ltd.
Volume‐Dependent Self‐Ignition Temperatures for Explosive Materials
Authors: Krause Gerhard
Published: February 2012

In this paper the differential equation of thermal explosion in the steady‐state approximation is established and solved. This solution is based on Fourier’s heat equation along with the Arrhenius heat source. The theory allows to draw conclusions on the thermal behaviour of any substance. The critical ambient temperature appears as a function of the apparent activation energy, Arrhenius temperature rate, temperature diffusivity, and the volume. The thermal stability of a chemically reactive material may be determined by means of these dependencies. Different volumes of five explosive materials were exposed to hot storage tests. These experiments generate appropriate kinetic parameters for these materials that are compared with known values from literature. Once these parameters are known, self‐ignition temperatures can be calculated for any arbitrary volume and boundary conditions. This is of major importance in the safe transportation and storage of explosives, munitions, and weapons.
Influence of an Electric Field on the Burning Behavior of Solid Fuels and Propellants
Authors: Young Gregory , Koeck Jeremy J. , Conlin Nathaniel T. , Sell Jordan L. , Risha Grant A.
Published: February 2012

An experimental study on the effects of an applied external electric field on the combustion behavior of solid fuels and solid propellants has been conducted. In an opposed flow burning configuration, application of an electric field was shown to extinguish a paraffin fuel and gaseous oxygen flame over a broad range of operating conditions. When subjected to the electric field, burning paraffin fuel strands were found to extinguish at various axial locations relative to the exit of the oxidizer gas jet. Extinguishment location was found to be a function of field strength as well as electrode surface area, while changes in polarity did not significantly alter the results. In addition, the combustion behaviors of two composite solid rocket propellants were studied while subjected to an external electric field. Both propellants were based on HTPB/AP combinations, with one propellant containing aluminum and the other being non‐aluminized. Application of an electric field to the composite solid rocket propellant strands demonstrated decreases in propellant burning rate under all operating conditions for both propellants including changes in polarity. The flame structure of the aluminized propellant was examined closely as the luminosity, flame length, and flame width varied significantly with field strength and burning location of the strand relative to the electrodes.
Lethal doses of ozone for control of all stages of internal and external feeders in stored products
Authors: Hansen Lise S , Hansen Peer , Jensen Karl‐Martin V
Published: February 2012

BACKGROUND: Gaseous ozone (O3) has potential for control of insects in stored grain. Previous studies have focused on freely exposed insects. Immatures of internal pests (e.g. Sitophilus spp. and most stages of Rhyzopertha dominica F.) are protected within kernels and probably require higher doses and/or longer treatment times for full control. A laboratory study determined the doses of ozone necessary for full control of freely exposed and internal stages of eleven stored‐product pest species. Test insects were three species of Sitophilus, R. dominica, Tribolium confusum Jacquelin du Val, T. castaneum Herbst, Plodia interpunctella Hübner, Sitotroga cerealella Olivier, Oryzaephilus surinamensis L., Ephestia kuehniella Zeller and Stegobium paniceum L. Insects were exposed to continuous flows of ozone in doses of 10–135 ppm and exposure times of 5–8 days. Dose‐mortality bioassays were conducted on three species of Sitophilus and P. interpunctella.

RESULTS: Freely exposed stages (with a few exceptions) were controlled with 35 ppm of ozone for 6 days. Full mortality of internal stages within kernels required exposure to 135 ppm for 8 days.

CONCLUSION: This study confirms that higher doses and/or longer treatment times are necessary for control of internal stages of stored‐product pests. Copyright © 2012 Society of Chemical Industry
Vkorc1 variation in house mice during warfarin and difenacoum field trials
Authors: Endepols Stefan , Klemann Nicole , Song Ying , Kohn Michael H
Published: February 2012

BACKGROUND: Field studies guided by genetic monitoring of Vkorc1 need to be done to implicate mutations conclusively with rodent control problems due to the presence of animals resistant to anticoagulant rodenticides. Rodent control success in relation to Vkorc1 genotypes in house mice (Mus musculus domesticus) was studied on two farms (I and II) in Germany. Tests were carried out to determine whether certain resistance profiles and Vkorc1 genotypes displayed dynamics over the course of sequential treatments with warfarin and difenacoum that were consistent with single nucleotide polymorphisms (SNPs) in Vkorc1 as indicators of resistance.

RESULTS: On farms I and II, respectively, three (A to C) and two (A and B) types of control problem with anticoagulants (i.e. proxies for resistance) were encountered in spatially segregated subunits: A = none; B = control problems with warfarin but not with difenacoum; C = control problems with both anticoagulants. Unexpectedly, resistance was encountered in a population where only Vkorc1 wild‐type mice were detected. In addition, the Arg58Gly Vkorc1 variant was found not to correlate with observed control failures.

CONCLUSION: Control problems were encountered that cannot be explained by Vkorc1 coding or intronic SNPs, and therefore are likely due to non‐coding Vkorc1 SNPs or due to other genetic or non‐genetic factors. © 2012 Society of Chemical Industry
GaN/InGaN heterojunction bipolar transistors with ultra‐high d.c. power density (>3 MW/cm2)
Authors: Lee Yi‐Che , Zhang Yun , Lochner Zachary M. , Kim Hee‐Jin , Ryou Jae‐Hyun , Dupuis Russell D. , Shen Shyh‐Chiang
Published: February 2012

We report ultra‐high‐power performance on npn GaN/InGaN double heterojunction bipolar transistors (DHBTs) that is directly grown on a free‐standing (FS) GaN substrate. Measured common‐emitter current gain (hfe) reaches 80. A quasi‐static I–V measurement shows that JC > 141 kA/cm2 and a power density of 3.05 MW/cm2 can be achieved for DHBTs grown on an FS‐GaN substrate. When the temperature is increased to 250 °C, a GaN/InGaN DHBT shows hfe = 43 and the offset voltage is reduced from 0.8 V at the room temperature to 0.3 V. Similarly, the knee voltage is reduced from 5.2 V at room temperature to 2.75 V at 250 °C. In this particular device, breakdown voltage (BVCEO) increases from 90 V at room temperature to 157 V at 250 °C.
Greatly enhanced performance of InGaN/GaN nanorod light emitting diodes
Authors: Bai J. , Wang Q. , Wang T.
Published: February 2012

For the first time we demonstrate InGaN/GaN‐based nanorod light emitting diodes (LEDs) with both very good current–voltage (I–V) characteristics and significantly enhanced emission. Our LED nanorods are fabricated based on InGaN/GaN LED epiwafers commercially available using self‐organised Ni nano‐mask and inductively coupled plasma (ICP) etching. In comparison with the conventional LED fabricated on the same wafer, our nanorod LEDs exhibit a great emission enhancement with a factor of 1.8. An extra novel step for device fabrication has been implemented, leading to significantly improved I–V characteristics with a forward‐bias voltage of 3.26 V at an injection current of 20 mA, while the forward‐bias voltage reported so far is typically 5–7 V for current nanorod LEDs. It is worth highlighting that our III‐nitride nanorod LEDs can be truly employed for practical applications.
Impurity photovoltaic effect in magnesium‐doped silicon solar cells with two energy levels
Authors: Yuan Jiren , Shen Honglie , Zhong Fulian , Deng Xinhua
Published: February 2012

In this paper, we have carried out a numerical study to evaluate the potential of the impurity photovoltaic (IPV) effect in magnesium‐doped silicon solar cells with two energy levels. We found that the cell efficiency can realize an absolute increase of above 2% due to the IPV effect. The efficiency improvement results from the extension of the infrared response of the solar cell. These results indicate that the IPV effect in silicon solar cells doped with magnesium is a potential means for improving cell efficiency.
The influence of inhomogeneities on broadening of fundamental transition in polar and nonpolar InGaN quantum wells dedicated for green emitters
Authors: Gladysiewicz Marta , Kudrawiec Robert
Published: February 2012

Broadening of the fundamental transition was calculated for polar and nonpolar InGaN QWs emitting in the green spectral range within the model of a ‘random quantum’ well (QW) [M. Gladysiewicz and R. Kudrawiec J. Phys.: Cond. Mater. 22, 485801 (2010)]. In order to simulate QW inhomogeneities in this model, it was assumed that the QW width, barrier widths and indium concentration vary with a Gaussian distribution where the nominal QW width, barrier widths and indium concentration correspond to the mean value in this distribution and their fluctuations correspond to the deviation from the main value. In this way the influence of the each parameter (QW width, barrier width, and indium concentration) on the broadening of the fundamental transition was considered independently and, finally, all the parameters were taken into account at the same time. It has been found that the same magnitude of QW width fluctuations and indium concentration fluctuations leads to much larger broadening of the fundamental transition for polar QWs than for nonpolar QWs. It means that the reduction of built‐in electric field in InGaN QWs can be a promising way to improve the homogeneity of light emission from this system. For polar InGaN QWs a significant reduction of polarization‐related electric fields can be obtained by a slight intentional doping in QW and/or barriers. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and characterization of Pt‐TiO2 nanofibers
Authors: Lee Deuk Yong , Cho Nam‐Ihn
Published: February 2012

Platinum (Pt) doped nanofibers were electrospun by using a Pt‐TiO2 precursor solution. The Pt‐TiO2 precursor solution was prepared by mixing the synthesized metal‐organic precursor solution containing Ti and Pt and the TiO2 sol. Amino acid, L‐lysine, was used as a bonding medium between Ti and Pt. The required amount of L‐lysine was determined to be 12 wt%. The dynamic viscosity and surface tension of Pt‐TiO2 solution were 16.6 cP and 21.4 mN/m, respectively. SEM results revealed that the diameters of TiO2 and Pt‐TiO2 nanofibers calcined at 500°C were similar regardless of the Pt presence. However, crystallite sizes of TiO2 and Pt‐TiO2 nanofibers determined by the Scherrer formula were 16 nm and 8 nm, respectively, suggesting that Pt metals may hinder the growth of the crystallite (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Origins of visible‐light emissions in porous silicon
Authors: Tit Nacir , Yamani Zain H. , Pizzi Giovanni , Virgilio Michele
Published: February 2012

The electronic and optical properties of porous silicon (p‐Si) have been theoretically investigated using the minimal sp3‐basis set tight‐binding method, with inclusion of second nearest neighbors and spin‐orbit interactions. A hypothetical model of p‐Si was assumed and calculations of band structures, with focus on bandgap energy Eg, oscillator strength (OS) and recombination rate (RR), were carried varying the porosity and the mean distance d between pores. Similar calculations were also performed for other confined silicon nanostructures as hydrogen‐passivated silicon nanocrystals (Si:H NCs) and silicon nanowires (Si‐NWs). For these two latter systems, the results of Eg versus the size d are found to be in excellent agreement with the available measured photoluminescence (PL) data of experimental p‐Si samples. On one hand, the results show that sizes in the range d = 1‐3 nm are responsible for emission in the visible‐light energy window. On the other hand, our results also suggest that the emission properties of p‐Si is strongly affected by the 2D and 3D quantum confinement (QC) characters of the involved band edge states. Furthermore, our theoretical values for the RR are found to be larger and closer to the experimental ones in the case of Si:H NCs with respect to the case of Si‐NWs. This fact suggests that the intense measured PL features are mainly due to 3D confined nanostructures (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure and temperature dependence of GaN/AlGaN high electron mobility transistor based sensors on a sapphire membrane
Authors: Edwards M. J. , Le Boulbar E. D. , Vittoz S. , Vanko G. , Brinkfeldt K. , Rufer L. , Johander P. , Lalinský T. , Bowen C. R. , Allsopp D. W. E.
Published: February 2012

This paper reports a high pressure sensor based on a GaN/AlGaN High Electron Mobility Transistor (HEMT) that uses its 375 mm thick sapphire substrate to provide a robust base and enables device operation up to at least 60 bar (6 MPa). Transduction of changes in ambient pressure occurs via piezoelectric and pyroelectric effects on the channel conductance. The HEMTs were strategically placed along an 8 mm2 GaN/AlGaN/GaN/sapphire chip; where the central 4 mm diameter behaves as a pressure sensitive ‘drumskin’. The location of peak response lies in the HEMT at the geometric centre of the drumskin, demonstrated by the change in IDS when the pressure was increased from 0 to 60 bar. The response of six strategically placed HEMTs along the chip's surface, were compared to a finite element model to predict sensor behaviour. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small current collapse in AlGaN/GaN HFETs on a‐plane GaN self‐standing substrate
Authors: Sugiyama T. , Honda Y. , Yamaguchi M. , Amano H. , Isobe Y. , Iwaya M. , Takeuchi T. , Kamiyama S. , Akasaki I. , Imade M. , Kitaoka Y. , Mori Y.
Published: February 2012

We measured drain bias stress effects and current collapse in AlGaN/ GaN heterostructure field‐effect transistors (HFETs) on a‐plane and c‐plane GaN substrates. An a‐plane AlGaN/GaN HFET (a‐HFET) shows small current collapse with a threshold voltage (Vth = ‐1.8 V). On the other hand, a c‐plane HFET (c‐HFET) with the same barrier thickness (20 nm) shows a small current collapse, although Vth was negatively large (Vth = ‐4 V).

Current collapse in a‐HFET was not large compared with that in conventional c‐HFET on GaN. A c‐HFET on sapphire was also measured. The current collapses in HFETs on sapphire were larger than that in HFETs on a GaN substrate. The current collapses in the thin‐barrier c‐HFET (Vth = ‐1.8 V) were particularly large. Therefore, an a‐plane device is promising for a small or positive Vth with small current collapse. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of high quality III‐N heterostructures using specialized MBE system
Authors: Petrov S. I. , Alexeev A. N. , Krasovitsky D. M. , Chaly V. P.
Published: February 2012

The growth of “thick” (200 nm) AlN layers on sapphire at 1100‐1150 °C using STE3N2 MBE system is shown to be the key step to obtain high quality GaN‐based heterostructures. An appropriate sequence of AlGaN transition layers grown on such an AlN both allows to reduce dislocation density in GaN down to 9×108‐1×109 cm‐2 in comparison with GaN layers grown on “thin” (10nm) low temperature AlN nucleation layer. Maximum electron mobility in 1.5 µm thick GaN silicon doped layer reaches 600‐650 cm2/V.s at electron concentrations (3‐5) ×1016 cm‐3. The results of use of GaN‐based heterostructures grown by STE3N2 for power DHFET production are also shown. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Titanium nitride as promising gate electrode for MOS technology
Authors: Lima Lucas P. B. , Moreira Milena A. , Diniz José A. , Doi Ioshiaki
Published: February 2012

Titanium nitride (TiN) films have been grown on Si (100) substrates by DC. reactive magnetron sputtering from a titanium (Ti) metallic target at different nitrogen partial pressures (80–10 sccm) and different power (500–1500 W). The effects of the nitrogen pressure and power on structural and electrical properties of TiN films were investigated by measuring their X‐ray diffraction (crystal orientation), Atomic Force Microscopy (surface roughness), four‐probe technique (electrical resistivity) and film thickness. It is show that deposition rate (13–65 nm/min) decrease with an increase of nitrogen pressure. The films have the grain size (0.001–0.027 μm2) along the sample surface and the size of the grain increase with an increase of nitrogen partial pressure. The X‐ray diffraction measurement show that films were crystalline (with preferred orientation (311)), but some of them were polycrystalline ((311) and (111) preferred orientation). These films have been used as gate electrodes in MOS capacitors, which were fabricated with TiN and SiNxOy as gate electrode and dielectric, respectively. With 20 minutes of annealing time, the extracted TiN work function and flat‐band voltage were about 4.65 eV and ‐0.29 V, which indicates that TiN can be used as mig‐gap electrode for MOS technology. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and electrical properties of sputtered InNO thin films
Authors: Sparvoli Marina , Mansano Ronaldo D. , Zambom Luis S. , Chubaci José F. D.
Published: February 2012

In this work we study the deposition of indium oxynitride prepared by reactive RF magnetron sputtering. This material shows multi‐functionality in electrical and photonic applications. It shows transparence in visible range, wide band gap, high resistivity, low linkage current and response for light. The deposition processes were performed in a home build magnetron sputtering system, using a four‐inch pure In (99.999%) target, nitrogen and oxygen as process gases. The pressure was kept constant in 1.33 Pa and the RF power (13.56 MHz) was constant 250 W. The optical band gap was estimated for samples deposited with 0%, 10%, 20%, 50%, 80% and 85% of oxygen concentration in the gas mixture and the band gap values obtained were 1.32 eV, 2.47 eV, 2.65 eV, 2.50 eV, 3.04 eV and 3.00 eV, respectively. The IxV analysis shows a low leakage current (∼10‐8 A). The increase in the oxygen concentration in the plasma promotes change in the character of these thin films from conductor to semiconductor material. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photocarrier drift mobility in ZnO at low temperature
Authors: Yamaguchi Hiroyuki , Ishidsuka Yousuke , Komiyama Takao , Chonan Yasunori , Aoyama Takashi
Published: February 2012

We have studied photocarrier drift mobility in ZnO in the temperature range between 30 and 280 K using a conventional time‐of‐flight (TOF) technique. Single crystal grown by the hydrothermal method was used as specimens. An electric field was applied in the direction parallel to the polar surfaces. We observed that shapes of the photocurrent transient changed with both applied electric field and temperature. The slopes of initial decays of the photocurrent became steeper with increase of the applied electric field strength. Transit time estimated from the photocurrent transient was in inverse proportion to the applied electric field. The highest drift mobility of 70 cm2V‐1s‐1 was obtained in the vicinity of 60 K for photoelectrons when the O‐surface was irradiated. While drift mobility showed the same temperature dependence as Hall mobility reported in previous work, its value was much smaller than that of Hall mobility. This discrepancy suggests that the multiple trapping effect due to the photocarrier trap centres is important at the ZnO surfaces. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel, AA/BB, AB/BA and Balaam's design: efficient and maximin choices when testing the treatment effect in a mixed effects linear regression
Authors: Candel Math J. J. M.
Published: February 2012

When examining the effect of treatmentAversusB, there may be a choice between a parallel group design, anAA/BBdesign, anAB/BAcross‐over and Balaam's design. In case of a linear mixed effects regression, it is examined, starting from a flexible function of the costs involved and allowing for subject dropout, which design is most efficient in estimating this effect. For no carry‐over, theAB/BAcross‐over design is most efficient as long as the dropout rate at the second measurement does not exceed2ρ/(1 + ρ),ρbeing the intraclass correlation. For steady‐state carry‐over, depending on the costs involved, the dropout rate andρ, either a parallel design or anAA/BBdesign is most efficient. For types of carry‐over that allow for self carry‐over, interest is in the direct treatment effect plus the self carry‐over effect, with either anAA/BBor Balaam's design being most efficient. In case of insufficient knowledge on the dropout rate orρ, a maximin strategy is devised: choose the design that minimizes the maximum variance of the treatment estimator. Such maximin designs are derived for each type of carry‐over. Copyright © 2012 John Wiley & Sons, Ltd.
A note on effective sample size for constructing confidence intervals for the difference of two proportions
Authors: Liu Guanghan F.
Published: February 2012

Proportion differences are often used to estimate and test treatment effects in clinical trials with binary outcomes. In order to adjust for other covariates or intra‐subject correlation among repeated measures, logistic regression or longitudinal data analysis models such as generalized estimating equation or generalized linear mixed models may be used for the analyses. However, these analysis models are often based on the logit link which results in parameter estimates and comparisons in the log‐odds ratio scale rather than in the proportion difference scale. A two‐step method is proposed in the literature to approximate the calculation of confidence intervals for the proportion difference using a concept of effective sample sizes. However, the performance of this two‐step method has not been investigated in their paper. On this note, we examine the properties of the two‐step method and propose an adjustment to the effective sample size formula based on Bayesian information theory. Simulations are conducted to evaluate the performance and to show that the modified effective sample size improves the coverage property of the confidence intervals. Copyright © 2012 John Wiley & Sons, Ltd.
Access‐polynomial‐based self‐healing group key distribution scheme for resource‐constrained wireless networks
Authors: Wang Qiuhua , Chen Huifang , Xie Lei , Wang Kuang
Published: February 2012

The self‐healing group key distribution scheme with revocation can deal with the problem of distributing session keys for secure group communication over an unreliable wireless network, with the capability to resist packet loss and collusion attack. However, existing access‐polynomial‐based self‐healing key management schemes have some problems, such as the small number of active group members, much redundancy in the key updating broadcast packet, and limited collusion attack resistance capability. In order to increase the number of active group members and improve the performance of self‐healing group key distribution schemes, we propose a self‐healing group key distribution scheme based on the access polynomial and one‐way hash key chain for resource‐constrained wireless networks in this paper. In our proposed scheme, by binding the time at which the user joins the group with the capability of recovering previous group session keys, some novel methods to construct the personal secret, the access polynomial, and the session key updating broadcast packet are presented. Compared with existing schemes under same conditions, analysis and simulation results show that our proposed scheme not only supports much more group members and sessions, but also provides a stronger security, considering that it can deal with more colluding users. Moreover, our proposed scheme is especially suitable to resource‐constrained wireless networks in a very bad environment. Copyright © 2012 John Wiley & Sons, Ltd.
Trust modeling for message relay control and local action decision making in VANETs
Authors: Zhang Jie , Chen Chen , Cohen Robin
Published: February 2012

In this paper, we present a trust‐modeling framework for message propagation and evaluation in vehicular ad hoc networks. In the framework, peers share information regarding road condition or safety, and others provide opinions about whether the information can be trusted. More specifically, our trust‐based message propagation model collects and propagates peers' opinions in an efficient, secure, and scalable way by dynamically controlling information dissemination. The trust‐based message evaluation model allows peers to derive a local action decision about whether to follow the information by evaluating the information in a distributed and collaborative fashion while taking into account others' opinions. Experimental results demonstrate that our proposed trust‐modeling framework promotes network scalability and system effectiveness, which are the two essentially important factors for the popularization of vehicular ad hoc networks, in information propagation and evaluation under the pervasive presence of false information. In particular, we clarify how our relay control serves to decrease the number of inappropriate actions taken on the basis of malicious information and enables honest peers to produce a greater number of deliveries within the network. Copyright © 2012 John Wiley & Sons, Ltd.
Passive layers developed on different tempers of AA7075 aluminium alloy after molybdenum implantation
Authors: Abreu C. M. , Cristóbal M. J. , Figueroa R. , Pena G.
Published: February 2012

The present work analyses the effect of molybdenum implantation at the nominal dose of 2×1016 Mo+ ions·cm−2 and acceleration voltage of 100 keV, on the passive layer formed on different tempers (T6 and T73) of AA7075 aluminium alloy. XPS and glancing angle X‐ray diffraction were used to characterize the implanted surface. The results obtained suggest that molybdenum is not integrating a new phase or compound in the Mo+‐implanted alloy. The most significant effect of molybdenum implantation is found at the oxide/metal interface, where a high segregation of copper (Cu 2p3/2 at 933.9 eV) is registered, reaching about 5 at% in both tempers. The passive layers developed on Mo+‐implanted AA7075 in both ageing conditions are formed by hydrated Al2O3 with Mg2+ in quantity and distribution similar to those grown on unimplanted tempers, but without Zn2+ in the outer oxide layer, indicating a more compact and protective alumina film. Copyright © 2012 John Wiley & Sons, Ltd.
The effect of highly ordered titania nanotube structures on hydrogen gas detection
Authors: Khameneh Asl Shahin , Alavi Babak , Ahmadi Sohrab
Published: February 2012

Different titanium oxide nanotubes were synthesized by anodizing the surface of titanium foil in two electrolyte solutions containing hydrofluoric acid and ethylene glycol. The samples were heat‐treated in a furnace. The microstructure and phase transformations of the nanotubes were investigated by X‐ray diffraction and field emission–scanning electron microscope. The nanoscale geometry of the nanotubes is responsible for the outstanding hydrogen gas sensitivities. A remarkable variation in electrical conductance has been observed in titanium oxide nanotube arrays that were prepared in hydrofluoric acid. This sensor exhibits a large resistance variation in the presence of very small quantities of hydrogen gas at 25 °C. The sensors show reversibility, repeatability, negligible drift, and wide dynamic range. Copyright © 2012 John Wiley & Sons, Ltd.
Social responsibility in new ventures: profiting from a long‐term orientation
Authors: Wang Taiyuan , Bansal Pratima
Published: February 2012

Socially responsible activities help create business value, develop strategic resources, and insure against risks, but also cost money and distract management. These prior findings are mainly based on established corporations and may not extend to new ventures in which the liability of newness may suppress some positive effects and amplify some negative impacts of socially responsible activities. New ventures whose strategic decisions have a long‐term orientation, however, are able to counteract their liability of newness and thereby generate net positive economic returns. We tested these relationships by surveying the chief executive officers and presidents and studying the signature Web sites of 149 new ventures. Copyright © 2012 John Wiley & Sons, Ltd.
Enterprise logic: explaining corporate attention to stakeholders from the ‘inside‐out’
Authors: Crilly Donal , Sloan Pamela
Published: February 2012

Why are some firms more effective than others at addressing stakeholder concerns? Conventional stakeholder theories focus on variables in the external environment and cannot adequately explain variance across firms operating in the same context. Our matched‐pair study of eight global corporations goes inside the firm and investigates the role of managerial cognition on corporate attention to stakeholders. We find that top management's conceptualization of the firm's relationship with society—which we name enterprise logic—prompts distinct foci of attention and potentially constrains how well a single firm can simultaneously attend to multiple stakeholders. These findings highlight the value of an ‘inside‐out’ perspective, centered on managerial cognition, in explaining why some firms address stakeholder concerns more effectively than their peers. Copyright © 2012 John Wiley & Sons, Ltd.
Weldability Evaluation and Microstructure Analysis of Resistance‐Spot‐Welded High‐Mn Steel in Automotive Application
Authors: Saha Dulal Chandra , Han Sangho , Chin Kwang Geun , Choi Ildong , Park Yeong‐Do
Published: February 2012

In this paper, resistance spot weldability of high‐Mn steels were investigated in order to get high reliability in welded joints of automotive components. Microstructural characterizations, cross‐tensile test (CTT), microhardness tests of spot welded parts were conducted. The effects of weld current on the microstructural characteristics, mechanical properties, and fracture modes were investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The hardness in the weld nugget was observed to be lower than that in the base metal (BM). In CTT, the failure initiation was observed to occur at the boundary of the weld nugget. Also welding imperfections of welded parts were investigated. Liquation cracking in heat affected zone (HAZ), porosity, and shrinkage cavity were found most common welding defects in welded parts. Furthermore, the effects of welding imperfections on weld quality and failure criteria were identified and discussed.
Formal passive testing of timed systems: theory and tools
Authors: Andrés César , Merayo Mercedes G. , Núñez Manuel
Published: February 2012

This paper presents a methodology to perform passive testing of timed systems. In passive testing, the tester does not interact with the implementation under test. On the contrary, execution traces are observed without interfering with the behaviour of the system. Invariants are used to represent the most relevant expected properties of the implementation under test. Intuitively, an invariant expresses the fact that each time the implementation under test performs a given sequence of actions, it must exhibit a behaviour in a lapse of time reflected in the invariant. There are two types of invariants: consequent and observational. The paper gives two algorithms to decide the correctness of proposed invariants with respect to a given specification and algorithms to check the correctness of a log, recorded from the implementation under test, with respect to an invariant. The soundness of this methodology is shown by relating it to an implementation relation. In addition to the theoretical framework, a tool called PASTE has been developed. This tool helps in the automation of the passive testing approach because it implements all the algorithms presented in this paper. PASTE takes advantage of mutation testing techniques in order to evaluate the goodness of an invariant according to its capability to detect errors in logs generated from mutants. An empirical study where PASTE was used to analyse a non‐trivial system is also reported. Copyright © 2012 John Wiley & Sons, Ltd.
Identification of functional differences between recombinant human α and β cardiac myosin motors
Authors: Deacon John C. , Bloemink Marieke J. , Rezavandi Heresh , Geeves Michael A. , Leinwand Leslie A.
Published: February 2012

The myosin isoform composition of the heart is dynamic in health and disease and has been shown to affect contractile velocity and force generation. While different mammalian species express different proportions of α and β myosin heavy chain, healthy human heart ventricles express these isoforms in a ratio of about 1:9 (α:β) while failing human ventricles express no detectable α-myosin. We report here fast-kinetic analysis of recombinant human α and β myosin heavy chain motor domains. This represents the first such analysis of any human muscle myosin motor and the first of α-myosin from any species. Our findings reveal substantial isoform differences in individual kinetic parameters, overall contractile character, and predicted cycle times. For these parameters, α-subfragment 1 (S1) is far more similar to adult fast skeletal muscle myosin isoforms than to the slow β isoform despite 91% sequence identity between the motor domains of α- and β-myosin. Among the features that differentiate α- from β-S1: the ATP hydrolysis step of α-S1 is ~ten-fold faster than β-S1, α-S1 exhibits ~five-fold weaker actin affinity than β-S1, and actin·α-S1 exhibits rapid ADP release, which is >ten-fold faster than ADP release for β-S1. Overall, the cycle times are ten-fold faster for α-S1 but the portion of time each myosin spends tightly bound to actin (the duty ratio) is similar. Sequence analysis points to regions that might underlie the basis for this finding.
Population dynamics of the cactus Mammillaria gaumeri: an integral projection model approach
Authors: Ferrer‐Cervantes Merari Esther , Méndez‐González Martha Elena , Quintana‐Ascencio Pedro‐Francisco , Dorantes Alfredo , Dzib Gabriel , Durán Rafael
Published: February 2012

The Cactaceae family in Mexico is particularly important because members of this family exhibit a high degree of endemism. Unfortunately, many species of the Cactaceae are threatened or endangered. We employed an integral projection model for studies of the population dynamics of Mammillaria gaumeri, an endemic cactus of the Yucatán characterized by a small population size. The integral projection model provides estimates of the asymptotic growth rate, stable size distribution, reproductive values, and sensitivities and elasticities of the growth rate to changes in vital rates. Nine locations of this species were studied along the Yucatan coast over a 9‐year period. Individuals were classified by plant volume. Most population growth rate (λ) values were below unity. The highest elasticity values corresponded to the survival of intermediate size individuals. The percentage of germination in the field was low, and consequently, fecundity values were also low. Reproductive values were observed to increase with plant volume. The stable size distribution of M. gaumeri was skewed toward small individuals. For all years, the kernel showed that individual survival determined the population growth rate.
Agronomic effects of a reciprocal translocation in a widely grown Spanish barley variety
Authors: Farré A. , Visioni A. , Lacasa-Benito I. , Cistué L. , Jansen J. , Romagosa I.
Published: February 2012

A large spontaneous reciprocal translocation is present in a widely grown Spanish barley cv. ‘Albacete’. It has been hypothesized that high popularity of ‘Albacete’ with farmers, particularly in semi-arid areas where barley is grown under rainfed conditions, may be due to the presence of this translocation. Agronomic effects of this translocation were studied at two locations and two growing seasons in a set of 245 doubled haploid lines derived from the F1s of four crosses involving ‘Albacete’. The results have shown a significant positive main effect of the translocation on the thousand kernel weight and a significant environment by translocation interaction for the thousand kernel weight, lodging and tiller number. However, the results do not support the hypothesis that this chromosomal structural change alone provides an increased adaptation to low-yielding sites.
Approximation and relaxation of perimeter in the Wiener space
Authors: Goldman M. , Novaga M.
Published: February 2012

We characterize the relaxation of the perimeter in an infinite dimensional Wiener space, with respect to the weak

L^{2}

-topology. We also show that the rescaled Allen–Cahn functionals approximate this relaxed functional in the sense of
Γ
-convergence.
A Secure Future
Authors: Bhattacharya Sanjoy
Published: February 2012

Medical History is embarking on an exciting new journey. Thanks to the Wellcome Trust, the ownership of this journal has passed to Cambridge University Press. The Press is committed to running the publication as its flagship journal in the history of medicine, related sciences and health, and is keen to offer authors full flexibility when it comes to publishing and archiving their articles. Medical History's editorial office has moved to the Centre for Global Health Histories at the University of York, which is housed within its Department of History; the Centre and Department are honoured to be associated to this world-leading journal.