bluuebunny/crossref_metadata_2025 huggingface dataset:
The socio-economic determinants of older people's health in Brazil: the importance of marital status and income
Authors: BÓS ANTÔNIO M. , BÓS ÂNGELO J.
Published: March 2007

Studies in various countries have reported that older people who are married have better health than older widows. This paper reports a replication of these analyses with Brazilian data. The main objective was to explore the relationships between marital status, individual and household income, and the health of men and women using ordered logistic regression with self-assessed health as the dependent variable. The explanatory variables of interest were gender, marital status, and individual and family income. The data are from a survey of 7,920 non-institutionalised older people resident in the southern state of Rio Grande do Sul in 1995. The survey used a structured, multi-disciplinary questionnaire, which collected information on demographic attributes, household composition, social relations, occupation, income and health status. The results show that widows were 20 per cent more likely to report better health than married women. The women without individual income had worse health than those who did, even after controlling for family income. For men, there were no significant differences in health by marital status. The main recommendation is that the health status and economic circumstances of married elderly women should be given more attention in both research and policy, certainly in Brazil and probably in other Latin American countries. Programmes of income support to the poorest households should include specific transfers to these elderly women. Brazil's Family Health and Older People's Health public programmes should place more emphasis on the health of elderly home-makers.
Constructions of ageing and narrative resistance in a commercial slimming group
Authors: GIMLIN DEBRA
Published: March 2007

This study focuses on the role of organisational setting and age in shaping individuals' narratives of embodied selfhood. It compares older and younger women's use of ‘narrative resistance’ to negotiate identity in light of their ageing and the negative social and personal meanings of being fat. Cordell and Ronai (1999) observed three types of narrative resistance among overweight people: loopholes, exemplars and continuums. This paper identifies two others: ‘justifications’, for behaviour that associated with weight gain, and ‘repentance’, for behaviour that reaffirmed a commitment to losing weight. Drawing from six months of participant-observation and in-depth interviews with 20 older and younger female clients of a commercial weight-loss organisation, this article shows that both the meanings women attributed to their experiences of slimming, and their opportunities for benefiting from organisational resources, varied by their stage in the lifecourse. The weight-loss group generated narrative strategies and opportunities for its members that were informed by both cultural constructions of ageing and the organisation's interests. While these strategies stopped short of empowering the clients to abandon restrictive dieting altogether, they did enable the older respondents to excuse temporary setbacks in weight loss and their deviation from (what they described as) the more exacting appearance standards of youth. At the same time, the strategic narratives reaffirmed constructions of ageing that present the older female body as uncontrollable and older women as unconcerned with physical attractiveness.
Editorial
Authors: Sanz Pedro J
Published: March 2007

The idea underlying this Special Issue arises from previous successfully international events organized in this robotics context. Thus, during 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems, hosted in Edmonton, Canada, a Workshop, with the same title was successfully organized by this guest editor. Moreover, this editor was involved in this research area, as co-Chair of the “Manipulation and Grasping Interest Group”, within the European Robotics Research Network (i.e. EURON), from 2001, organizing also a couple of International Summer Schools, supported by EURON, on these topics (Spain, 2001 and 2004). On the other hand, as time goes by, more and more robotics applications are oriented towards working in all kind of service domains, such as hospitals, museums, etc. Hence, the interest on those robotic systems, integrating manipulation and navigation capabilities, namely mobile manipulators, is drastically increasing around the entire world. Therefore, this special issue is trying to face this new scenario providing a comprehensive overview of some key topics, foundations and applications within the Mobile Manipulators context, including human-robot interaction aspects and critical issues related with navigation and manipulation performance, among others.
Update on fruit antioxidant capacity: a key tool for Mediterranean diet
Authors: Battino Maurizio , Mezzetti Bruno
Published: March 2007

Objective

To review and update the most relevant research dealing with the antioxidant properties of fruits which can be useful in Mediterranean and other healthy diets.

Design

Personal perspectives and late data.

Setting

International

Results

The evaluation of total antioxidant capacity of fruits is of pivotal importance in assessing the nutritional attributes of these products. By means of specific breeding programmes, it is possible to select antioxidant-enriched fruit varieties. These features are susceptible to be improved through generations in order to release fruits with enhanced nutritional features.

Conclusions

The availability of high quality and nutritionally enriched fruit at competitive costs may be a useful tool in the planning of healthy diets.
Transmitting Mediterranean food culture through art: a creative interdisciplinary approach
Authors: Dernini Sandro
Published: March 2007

Objective

As a qualitative problem solving method, to manage the accelerating phenomenon of overweight and obesity among children and adolescents as well as to promote the Mediterranean Diet and the diversity of the Mediterranean Food Cultures heritage, it is presented a creative interdisciplinary approach through art.

Design

Taking into account that young generations are becoming the highest majority of the consumer population in the Southern and Eastern Mediterranean countries, it is reported the artist practice and the creative community-based interdisciplinary experience of Plexus International, a network of artists and scientists of various nationalities and disciplines.

Setting

Mediterranean Region and International.

Subject

Young Populations.

Results

Through the Ark of the Well Being project, artists and scientists have collaborate together, promoting The 2005 Rome Call for a Common Action in the Mediterranean and raising more attention on the erosion of the cognitive capacities of young generations by hunger and malnutrition.

Conclusions

A creative interdisciplinary approach was developed to transmit through art Mediterranean food culture with the aim to achieve a broader nutritional well being.
Chronische Obstipation
Authors: Degen
Published: March 2007

Die Beschwerden der chronischen Obstipation können die Lebensqualität eines Patienten erheblich beeinträchtigen. Das Krankheitsempfinden ist dabei nicht nur von objektiven Parametern sondern auch von der subjektiven Wahrnehmung geprägt. Dies wird in den sogenannten Rom-III-Kriterien zur Diagnose der chronischen Obstipation mitberücksichtigt. In der Mehrzahl der Patienten mit Obstipation findet sich keine eindeutige Pathologie. In einer kleineren Patientengruppe lässt sich aber isoliert oder in Kombination ein zugrunde liegender verzögerter Kolontransit oder eine Beckenbodendysfunktion nachweisen. Sekundäre extraintestinale Ursachen sind vor allem bei einer erstmaligen Evaluation zu suchen. Neben den allgemeinen klinischen Untersuchungen allenfalls verbunden mit einer Koloskopie, bieten sich zur Diagnostik spezifische Funktionsuntersuchungen (Transitmessungen, Defäkographie) an. Therapeutisch stehen in erster Linie die unterschiedlichen stuhlregulierenden Medikamente im Vordergrund. In ausgewählten Fällen können Biofeedbacktraining oder eine chirurgische Intervention erfolgreich sein.
Sensitivity of modelled atmospheric circulation to the representation of stable boundary layer processes
Authors: King J. C. , Jrrar A. , Connolley W. M.
Published: March 2007

We examine the sensitivity of the modelled climate of the third generation Hadley Centre climate model to changes in the parametrization of surface and boundary‐layer fluxes under stable stratification. Replacing the model's standard parametrization with one in which fluxes decrease more rapidly with increasing stability generates statistically‐significant changes in modelled 500 hPa height. The largest changes are seen across the North Atlantic and North Pacific and occur during Northern Hemisphere summer, when persistent stable atmospheric boundary layers form over the western sides of these oceans. The atmospheric response in a coupled version of the model is stronger than in the atmosphere‐only version, suggesting that feedbacks involving sea surface temperatures, surface fluxes and atmospheric circulation are important in determining the response.
Evidence for thin oceanic crust on the extinct Aegir Ridge, Norwegian Basin, NE Atlantic derived from satellite gravity inversion
Authors: Greenhalgh E. E. , Kusznir N. J.
Published: March 2007

Satellite gravity inversion incorporating a lithosphere thermal gravity correction has been used to map crustal thickness and lithosphere thinning factor for the NE Atlantic. Predicted oceanic crustal thicknesses in the Norwegian Basin are between 4 and 7 km on the extinct Aegir Ridge, increasing to 9 – 14 km at the margins, consistent with volcanic margin continental breakup at the end of the Paleocene. The observation (from gravity inversion and seismic refraction studies) of thin oceanic crust produced by the Aegir Ridge in the Oligocene may have implications for the temporal evolution of asthenosphere temperature under the NE Atlantic during the Tertiary. Thin Oligocene oceanic crust may imply cool (normal) asthenosphere temperatures during the Oligocene in contrast to elevated asthenosphere temperatures in the Paleocene and Miocene‐Recent as indicated by the formation of volcanic margins and Iceland respectively.
Simultaneous induction of the four subunits of the TRAP complex by ER stress accelerates ER degradation
Authors: Nagasawa Koji , Higashi Toshio , Hosokawa Nobuko , Kaufman Randal J , Nagata Kazuhiro
Published: March 2007

The mammalian translocon‐associated protein (TRAP) complex comprises four transmembrane protein subunits in the endoplasmic reticulum. The complex associates with the Sec61 translocon, although its function in vivo remains unknown. Here, we show the involvement of the TRAP complex in endoplasmic reticulum‐associated degradation (ERAD). All four subunits are induced simultaneously by endoplasmic reticulum stresses from the X‐box‐binding protein 1/inositol‐requiring 1α pathway. RNA interference knockdown of each subunit causes disruption of the native complex and significant delay in the degradation of various ERAD substrates, including the α1‐antitrypsin null Hong Kong variant (NHK). In a pulse‐chase experiment, the TRAP complex associated with NHK at a late stage, indicating its involvement in the ERAD pathway rather than in biosynthesis of nascent polypeptides in the endoplasmic reticulum. In addition, the TRAP complex bound preferentially to misfolded proteins rather than correctly folded wild‐type substrates. Thus, the TRAP complex induced by the unfolded protein response pathway might discriminate ERAD substrates from correctly folded substrates, accelerating degradation.
Characteristics of pulsed plasma doping sources for ultrashallow junction formation
Authors: Agarwal Ankur , Kushner Mark J.
Published: March 2007

Plasma doping of semiconductors is being investigated for low energy ion implantation to form ultrashallow junctions. In plasma doping, ions are extracted from a quasicontinuous plasma using a pulsed bias on the substrate. Plasma-based implantation techniques have the potential for higher throughput than those attainable with conventional accelerator beamlines due to the higher current densities possible with plasma sources. In this work, results from a computational investigation of plasma sources for doping of semiconductors will be discussed. An inductively coupled plasma (ICP) was used to generate ions at pressures of a few to tens of millitorr. A pulsed bias up to −20kV having lengths of tens of microseconds was applied to the substrate to accelerate the ions. Results are presented for Ar∕NF3 gas mixtures which serve as surrogates for the Ar∕BF3 mixtures that would provide boron doping. The consequences of bias voltage waveform, ICP power, operating pressure, and aspect ratio of the reactor on discharge characteristics and ion energy and angular distributions (IEADs) to the substrate will be discussed. The shape of the bias waveform has important consequences on the IEADs not only because of the transit times of the ions but also due to the instabilities that may be launched into the plasma. The aspect ratio of the reactor influences the angular uniformity of the IEADs, particularly when using large biases.
Theoretical and numerical studies of relativistic ion and electron holes in plasmas
Authors: Eliasson B. , Shukla P. K.
Published: March 2007

Analytical and numerical studies of the dynamics of relativistic electron and ion holes in a collisionless plasma are presented. Ion and electron holes are localized Bernstein-Greene-Kruskal modes characterized by particle populations trapped in the self-consistent electrostatic potential associated with the holes. Electromagnetic radiation can be trapped in relativistic electron holes due to a combination of the density fluctuations and the relativistic mass increase of the electrons, which changes locally the dielectric properties of the plasma and leads to a localization of the electromagnetic wave envelopes. Relativistic ion holes may be formed in active galactic nuclei, supernova remnant shocks, pulsar winds, and gamma-ray burst jets where relativistic plasma streams are thought to exist. The relativistic ion holes may be responsible for the acceleration of particles to GeV energies. The analytic solutions for relativistic electron and ion holes are employed as initial conditions for numerical simulations in which the dynamics and stability of the phase-space holes are investigated. The results have relevance for intense laser-plasma experiments and for astrophysical plasmas.
A possible realization of spin filter using a quantum wire with Rashba spin-orbit coupling
Authors: Liu Genhua , Zhou Guanghui
Published: March 2007

We study theoretically the spin-polarized electron transport properties for a weak Rashba spin-orbit coupling (SOC) quantum wire connected nonadiabatically to two normal-conductor electrode leads. The influence of both the mode mixing due to wire-lead connection and Rashba SOC split on the spin-polarized electron transport is treated simultaneously by means of scattering matrix within the framework of effective free-electron approximation. The analytical analysis with numerical examples demonstrates that the purely spin-polarized current can occur for the system with an appropriate system geometry and material parameters. Our result may imply a simple approach to the design of a spin filter device without containing any magnetic materials or applying a magnetic field.
Ferromagnetic one dimensional Ti atomic chain
Authors: Hong Jisang
Published: March 2007

Using the full potential linearized augmented plane wave method, we have explored the magnetic properties of one dimensional (1D) Ti atomic chain. Interestingly, we have observed that the 1D Ti atomic chain has ferromagnetic ground state even on NiAl(110) surface. In addition, it has been found that the magnetic dipole interaction is a key factor in the study of magnetic anisotropy, not the magnetocrystalline anisotropy arising from spin-orbit interaction.
Magnetization-induced optical nonlinearity in ferromagnetic GaMnAs
Authors: Han Kang-Jeon , Kim Ji-Hee , Yee Ki-Ju , Liu X. , Furdyna J. K. , Hache F.
Published: March 2007

We report the observation of a coherent nonlinear signal in pump-probe experiments on a ferromagnetic GaMnAs. The coherent signal, which is originating due to coherent interaction between pump and probe beams, depends on the polarization configuration of each beam and follows the sample magnetization as it changes with the applied magnetic field and∕or the sample temperature.
Influence of defects on the magnetism of Mn-doped ZnO
Authors: Iuşan D. , Sanyal B. , Eriksson O.
Published: March 2007

The properties of dilute magnetic semiconductors are usually strongly influenced by the defects present in the system. Ab initio calculations may provide valuable insight for the microscopic understanding of the interactions with defects. Here, we present studies of Mn-doped ZnO in the presence of several defects by a combined approach of ab initio electronic structure calculations using Korringa-Kohn-Rostoker-coherent potential approximation and Monte Carlo simulations (MCSs). Electronic structure and magnetic interactions have similar trends for wurtzite and zinc-blende crystal structures. A weak antiferromagnetic interaction has been found for 5% Mn doping in defect-free ZnO. Defects such as O vacancies and Zn interstitials lead to antiferromagnetic interactions between the Mn atoms, while Zn vacancies and oxygen substitution by nitrogen yield ferromagnetic interactions. As the concentration of Mn is low and the exchange interactions are short ranged, MCSs show small values of Curie temperatures (not more than 50K). However, for a few cases with codoping of Mn and defects, we obtained higher Curie temperatures (around 130K). Estimates of the Curie temperatures, assuming an average separation of the Mn atoms in the mean-field solution of Heisenberg model, are in very good agreement with the results obtained from MCS.
The electronic structure of ultrathin aluminum oxide film grown on FeAl(110): A photoemission spectroscopy
Authors: Kizilkaya O. , Senevirathne I. C. , Sprunger P. T.
Published: March 2007

The electronic structure of the ultrathin aluminum oxide grown on the FeAl(110) surface has been investigated with angle-resolved photoemission spectroscopy. Previous scanning tunneling microscopy studies have revealed that exposing the clean FeAl(110) surface to 1000l of oxygen at 850°C forms a homogeneous hexagonal oxide film with a thickness of approximately 10Å. Core level photoemission spectra of FeAl constituents indicate that Al is the only metal species present in the oxide film. The measured band dispersion of the oxide thin film indicates a two dimensional electronic structure parallel to the plane of the thin film due to the limited thickness of the oxide thin films. The appearance of a peak in the anticipated band gap of the bulk oxide film suggests a unique electronic structure of the two dimensional oxide film. This latter observation is correlated with previous scanning tunneling microscopy results to elucidate the structure of the ultrathin alumina film grown on FeAl(110).
Microstructure and mechanical property characterizations of metal foil after microscale laser dynamic forming
Authors: Cheng Gary J. , Pirzada Daniel , Ming Zhou
Published: March 2007

This article discusses the feasibility of a new microforming technique—laser dynamic forming (LDF). LDF is a new hybrid forming process, combining the advantages of laser shock peening, and metal forming, with an ultra high strain rate forming utilizing laser shock waves. Experiments are conducted on copper foils to demonstrate this forming process. After the forming process, the mechanical and microstructure of the formed work piece will be characterized. Electron backscatter diffraction will be used to investigate the grain microstructure and misorientations quantitatively. The residual stress distributions will be measured using x-ray diffraction. The key factors for the improved formability of this high strain rate microforming process will be discussed in detail. With further development, LDF may become an important microforming technology for various materials.
Silicon dry oxidation kinetics at low temperature in the nanometric range: Modeling and experiment
Authors: Krzeminski Christophe , Larrieu Guilhem , Penaud Julien , Lampin Evelyne , Dubois Emmanuel
Published: March 2007

Kinetics of silicon dry oxidation is investigated theoretically and experimentally at low temperature in the nanometer range where the limits of the Deal and Grove model become critical. Based on a fine control of the oxidation process conditions, experiments allow the investigation of the growth kinetics of nanometric oxide layer. The theoretical model is formulated using a reaction rate approach. In this framework, the oxide thickness is estimated with the evolution of the various species during the reaction. Standard oxidation models and the reaction rate approach are confronted with these experiments. The interest of the reaction rate approach to improve silicon oxidation modeling in the nanometer range is clearly demonstrated.
Ion collection by a sphere in a flowing highly collisional plasma
Authors: Khrapak S. A. , Klumov B. A. , Morfill G. E.
Published: March 2007

Ion collection by a small negatively biased sphere in flowing highly collisional plasmas is investigated. Ion trajectories in the vicinity of the sphere are obtained from the solution of the ion equation of motion. From the analysis of the trajectories, the total ion flux to the sphere is determined and the sphere floating potential is calculated from the balance between ion and electron fluxes. The asymmetry in ion collection by the upstream and downstream sides of the sphere is quantified. The results obtained can be important in the context of complex (dusty) plasmas, as well as in the context of probe theory.
Geometric considerations for diffusion in polycrystalline solids
Authors: Chen Ying , Schuh Christopher A.
Published: March 2007

Mass transport in polycrystals is usually enhanced by short-circuit diffusion along various defect paths, e.g., grain boundaries, dislocation cores, and triple junctions. In the “kinetic-A” regime, diffusion fields associated with the various diffusion paths overlap each other, forming a macroscopically homogeneous diffusion profile that can be described by an effective diffusion coefficient. Here, we develop a composite diffusion model for polycrystals based on realistic arrangements between various microstructural elements, which usually exhibit complex network morphologies. Asymmetric effective medium equations and power-law scaling relationships are used to evaluate the effective diffusivity of a general isotropic polycrystal, and are compared to predictions of the simple arithmetic rule of mixtures used frequently in the literature. We also examine the grain size and temperature dependence of polycrystalline diffusion in terms of the apparent grain size exponent and activation energy, which in turn provide the basis by which we assess dominant diffusion processes and construct generalized diffusion mechanism maps. Implications of geometry on experimental diffusivity measurements are also discussed.
Effect of a MgO interlayer on the structural and magnetic properties of Co2Cr0.6Fe0.4Al thin films epitaxially grown on GaAs substrates
Authors: Yano T. , Uemura T. , Matsuda K.-i. , Yamamoto M.
Published: March 2007

The effect of a MgO interlayer on the structural and magnetic properties of Co2Cr0.6Fe0.4Al (CCFA) thin films epitaxially grown on GaAs substrates by sputtering was investigated. When the MgO interlayer thickness was 1.0nm or less, the CCFA films were grown with a cube-on-cube relation to GaAs and no significant decrease in either the x-ray diffraction intensity or saturation magnetization was observed. In contrast, when the MgO thickness was 1.5nm or more, the CCFA film was rotated by 45° in the (001) plane with respect to GaAs, and both the x-ray diffraction intensity and saturation magnetization decreased. All samples showed strong magnetic anisotropy, in which a uniaxial anisotropy with an easy axis of [110]GaAs or [1−10]GaAs dominated with a slight cubic anisotropy having an easy axis of ⟨110⟩CCFA superimposed.
Enhanced magnetoresistance of La2∕3Ca1∕3MnO3∕CeO2 nanocystalline composites synthesized by polymer-network gel method
Authors: Yao L. D. , Zhang W. , Zhang J. S. , Yang H. , Li F. Y. , Liu Z. X. , Jin C. Q. , Yu R. C.
Published: March 2007

Using a dispersing particle polymer-network gel method, we prepared xLa2∕3Ca1∕3MnO3∕(1−x)CeO2 nanocystalline composites, where the average grain sizes of La2∕3Ca1∕3MnO3 and CeO2 are about 30nm and less than 10nm, respectively. The magnetoresistance of the sintered composites is explored as a function of the ratio of metal/insulator, temperature, and magnetic field. The system exhibits metallic percolation threshold at x=xp∼35%, around which the high field magnetoresistance has a maximum (∼70%) at 50K and 5T, and the low field magnetoresistance value is close to 16% at 5K and 0.05T.
Dust ion-acoustic shock waves in an adiabatic dusty plasma
Authors: Rahman Armina , Sayed Fatema , Mamun A. A.
Published: March 2007

The properties of dust ion-acoustic shock waves in an unmagnetized dusty plasma, whose constituents are adiabatic ion fluid, Boltzmann electrons, and static dust, are investigated by employing the reductive perturbation method. The Burgers equation is derived and its stationary analytical solution is numerically analyzed. It has been found that both the amplitude and the width decrease with the increase of the ion-fluid temperature. The implications of our results in space and laboratory dusty plasmas are briefly discussed.
Low-temperature differential-thermal analysis to measure variations in entropy
Authors: Schilling A. , Reibelt M.
Published: March 2007

We describe how we can precisely measure variations in the entropy S of small solid samples below room temperature, as a function the temperature T or the external magnetic field H, respectively. A simple differential-thermal analysis technique allows, in principle, for the measurement of variations in S without any instrumental broadening of the data. The method is particularly well suited for the detection of sharp phase transitions in samples of milligram size.
Method for measurement of the density of thin films of small organic molecules
Authors: Xiang Hai-Feng , Xu Zong-Xiang , Roy V. A. L. , Che Chi-Ming , Lai P. T.
Published: March 2007

An accurate and sensitive method is reported to measure the thin-film density of vacuum-deposited, small-molecular organic semiconductor materials. A spectrophotometer and surface profiler had been used to determine the mass and thickness of organic thin film, respectively. The calculated density of tris-(8-hydroxyquinolato) aluminum (Alq3) thin film was 1.31±0.01 g∕cm3. Vacuum pressures and thin-film growth rates are found to have less impact on the thin-film density of organic material. However, the thin-film density of organic material strongly depends on its chemical structure and molecular weight. Specifically, the chemical structure determines the density of organic material that affects the molecular volume and intermolecular stacking.
Evolution of nanodomains in 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 single crystals
Authors: Shvartsman V. V. , Kholkin A. L.
Published: March 2007

High-resolution studies of polar structures have been performed on the 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 (0.9PMN-0.1PT) single crystals by piezoresponse force microscopy. A complex pattern of nanosized polar regions (nanodomains) was observed above the temperature of the structural phase transition. Autocorrelation function technique applied to the analysis of the obtained images revealed clear self-organization of the nanodomains in (110) crystallographic directions and allowed estimating their mean size (∼70 nm at room temperature). Upon heating, the gradual decay of the piezoresponse contrast took place, however, the nanodomains could be still observed at temperatures as high as 385 K. The nature of the observed phenomena is attributed to a peculiar transient state between relaxor and ferroelectric, which developed near the crystal’s surface.
Spectroscopic study of the effect of N and F codoping on the spatial distribution of Er3+ dopant ions in vitreous SiO2
Authors: Gubaidullin R. R. , Orlinskii S. B. , Rakhmatullin R. M. , Sen S.
Published: March 2007

Pulsed electron paramagnetic resonance (EPR) spectroscopy has been used to study the influence of codoping with N and/or F on the clustering of Er3+ ions in vitreous SiO2. Measurements of echo-detected EPR, spin-lattice and phase memory relaxation times, and electron spin-echo envelope modulation (ESEEM) were made in the X band. Er-N, Er-F, and Er-N-F codoped glasses show clear evidence of clustering of Er3+ ions at concentration levels ranging between 6.67×1018 cm−3 and 6.67×1019 cm−3. However, the relatively long phase memory relaxation time and the observability of ESEEM in the Er-N-F codoped glass strongly indicate that combined codoping with N and F is more effective in homogenization of the spatial distribution of Er3+ ions in vitreous SiO2, although, the structural mechanism remains unclear. The ESEEM results provide evidence in favor of the presence of N in the vicinity of the Er3+ ions in Er-N-F codoped vitreous SiO2.
Spin-orbit effect in the energy pooling reaction O2(aΔ1)+O2(aΔ1)→O2(bΣ1)+O2(XΣ3)
Authors: Lu Rui-Feng , Zhang Pei-Yu , Chu Tian-Shu , Xie Ting-Xian , Han Ke-Li
Published: March 2007

Five-dimensional nonadiabatic quantum dynamics studies have been carried out on two new potential energy surfaces of S2(A′1) and T7(A″3) states for the title oxygen molecules collision with coplanar configurations, along with the spin-orbit coupling between them. The ab initio calculations are based on complete active state second-order perturbation theory with the 6-31+G(d) basis set. The calculated spin-orbit induced transition probability as a function of collision energy is found to be very small for this energy pooling reaction. The rate constant obtained from a uniform J-shifting approach is compared with the existing theoretical and experimental data, and the spin-orbit effect is also discussed in this electronic energy-transfer process.
Noncontact measurement of electrostatic fields: Verification of modeled potentials within ion mobility spectrometer drift tube designs
Authors: Scott Jill R. , Tremblay Paul L.
Published: March 2007

The heart of an ion mobility spectrometer is the drift region where ion separation occurs. While the electrostatic potentials within a drift tube design can be modeled, no method for independently validating the electrostatic field has previously been reported. Two basic drift tube designs were modeled using SIMION 7.0 to reveal the expected electrostatic fields: (1) A traditional alternating set of electrodes and insulators and (2) a truly linear drift tube. One version of the alternating electrode/insulator drift tube and two versions of linear drift tubes were then fabricated. The stacked alternating electrodes/insulators were connected through a resistor network to generate the electrostatic gradient in the drift tube. The two linear drift tube designs consisted of two types of resistive drift tubes with one tube consisting of a resistive coating within an insulating tube and the other tube composed of resistive ferrites. The electrostatic fields within each type of drift tube were then evaluated by a noncontact method using a Kelvin-Zisman type electrostatic voltmeter and probe (results for alternative measurement methods provided in supplementary material). The experimental results were then compared with the electrostatic fields predicted by SIMION. Both the modeling and experimental measurements reveal that the electrostatic fields within a stacked ion mobility spectrometer drift tube are only pseudo-linear, while the electrostatic fields within a resistive drift tube approach perfect linearity.
High speed single charge coupled device Cranz-Schardin camera
Authors: Deblock Y. , Ducloux O. , Derbesse L. , Merlen A. , Pernod P.
Published: March 2007

This article describes an ultrahigh speed visualization system based on a miniaturization of the Cranz-Schardin principle. It uses a set of high power light emitting diodes (LEDs) (Golden Dragon) as the light source and a highly sensitive charge coupled device (CCD) camera for reception. Each LED is fired in sequence and images the refraction index variation between two relay lenses, on a partial region of a CCD image sensor. The originality of this system consists in achieving several images on a single CCD during a frame time. The number of images is 4. The time interval between successive firings determines the speed of the imaging system. This time lies from 100nsto10μs. The light pulse duration lies from 100nsto10μs. The principle and the optical and electronic parts of such a system are described. As an example, some images of acoustic waves propagating in water are presented.
Investigations of enhanced device characteristics in pentacene-based field effect transistors with sol-gel interfacial layer
Authors: Cahyadi T. , Tey J. N. , Mhaisalkar S. G. , Boey F. , Rao V. R. , Lal R. , Huang Z. H. , Qi G. J. , Chen Z.-K. , Ng C. M.
Published: March 2007

Pentacene films grown on sol-gel silica dielectrics showed a significant enhancement in field effect mobility, threshold voltages, and subthreshold swings. This letter investigates the contributing factors for the enhanced device characteristics. The smoother and more hydrophobic film surfaces of sol-gel silica (rms roughness of ∼1.9Å and water contact angle of ∼75°) induced larger pentacene grains, yielding mobilities in excess of ∼1cm2∕Vs at an operating voltage of −20V. Different sol-gel silica film thicknesses showed similar trends in improved performances, indicating that this phenomenon is clearly a semiconductor-dielectric interface phenomenon rather than a bulk dielectric effect.
Flexible conjugated polymer photovoltaic cells with controlled heterojunctions fabricated using nanoimprint lithography
Authors: Kim Myung-Su , Kim Jin-Sung , Cho Jae Cheol , Shtein Max , Kim Jinsang , Guo L. Jay , Kim Jinsang
Published: March 2007

The authors describe conjugated polymer-based photovoltaic devices in which the shape and area of the interface between the electron donor and acceptor layers were controllably varied using nanoimprint lithography. The short circuit current is shown to increase with the interfacial area of the heterojunction, without affecting the open circuit voltage. The fill factor and power conversion efficiency are also shown to increase with donor-acceptor interfacial area.
Nonresonant electrical injection of excitons in an InGaAs quantum well
Authors: Bajoni D. , Miard A. , Lemaître A. , Bouchoule S. , Bloch J. , Tignon J.
Published: March 2007

The authors report on electroluminescence measurements combined with photoluminescence excitation spectroscopy on a single InGaAs quantum well placed in the intrinsic region of a p-i-n photodiode. They show that at low current density, the spectra are dominated by the spectrally narrow excitonic emission. Moreover when increasing carrier injection, they observe the progressive transition from excitons into free electron-hole pairs. This structure meets all criteria to be integrated in a semiconductor microcavity and the present demonstration of exciton electroluminescence is the first step toward the achievement of the strong coupling regime under electrical injection.
Optical properties of dilute nitrogen GaInNAs quantum dots
Authors: Tomić Stanko
Published: March 2007

The authors present a theoretical study of the ground state optical transition matrix element in quantum dots (QDs) with a dilute amount of nitrogen. They have investigated the interplay between the nitrogen to the conduction band mixing and piezoelectric field on the optical matrix element. With a reduced amount of indium and an increased amount of nitrogen in the QD, the optical matrix element becomes on the average larger and less sensitive to the variation of both the QD shape and size than is the case of an InNAs QD. The optical characteristics at room temperature and 1.5μm wavelength are discussed.
Unusual size dependence of the optical emission gap in small hydrogenated silicon nanoparticles
Authors: Wang X. , Zhang R. Q. , Lee S. T. , Niehaus T. A. , Frauenheim Th.
Published: March 2007

It is well known that the electronic and optical absorption gaps of hydrogenated silicon nanoparticles are inversely proportional to the particle size. Here, the authors show that their optical emission gaps are remarkably different and dully dependent on the size for those smaller than 1.5nm, based on their excited-state calculations of a series of nanoparticles from Si5H12 to Si199H140 using a time-dependent tight-binding density-functional method. It is revealed that this unusual size dependence is due to the strong excited-state structure relaxation in the particle core region that becomes significant when the size decreases.
Tension-compression asymmetry in homogeneous dislocation nucleation in single crystal copper
Authors: Tschopp M. A. , McDowell D. L.
Published: March 2007

This letter addresses the dependence of homogeneous dislocation nucleation on the crystallographic orientation of pure copper under uniaxial tension and compression. Molecular dynamics simulation results with an embedded-atom method potential show that the stress required for homogeneous dislocation nucleation is highly dependent on the crystallographic orientation and the uniaxial loading conditions; certain orientations require a higher stress in compression (e.g., [110] and [111]) and other orientations require a higher stress in tension ([100]). Furthermore, the resolved shear stress in the slip direction is unable to completely capture the dependence of homogeneous dislocation nucleation on crystal orientation and uniaxial loading conditions.
Two-step preionization scheme for discharge pumped KrF excimer lasers
Authors: Szatmári S. , Janicskó J. , Bohus J.
Published: March 2007

The beam homogeneity and stored energy of discharge pumped KrF excimer amplifiers are critically dependent on the preionization level of the active medium and on the rise time of the electric excitation pulse. Here a scheme is presented to increase the effectiveness of the preionization and to improve the rise time of the pump pulse by the use of the auto-spark-gap UV preionization of increased gap separation. The modified charging circuit has been proven to enhance the discharge quality and the amplification properties of the excimer module. The increased temporal jitter of the preionization sparks of large gap separation is eliminated by an additional pre-preionization scheme. The circuit is especially well suited for short-pulse KrF amplifiers.
Current-induced asymmetric I-V behavior of La0.82Ca0.18MnO3 thin films and its tunability
Authors: Sun Y. H. , Zhao Y. G. , Xiong C. M.
Published: March 2007

Asymmetric I-V behaviors induced by large currents in La0.82Ca0.18MnO3 (LCMO) films are studied. The contribution of LCMO to the asymmetric I-V behaviors is demonstrated by eliminating the contribution of the LCMO/electrode interface. The asymmetric I-V behaviors of LCMO can be tuned by the negative voltage pulse and positive current excitations between two resistive states. A band bending model based on the local oxygen electromigration at the grain boundaries of LCMO is proposed to account for the results. This work is helpful for understanding the mechanism of the current effect on manganites and also its applications.
Observation of protein-protein interaction by dielectric relaxation spectroscopy of protein solutions for biosensor application
Authors: Mazzeo Brian A. , Flewitt Andrew J.
Published: March 2007

Dielectric spectroscopy was used to measure the dielectric relaxation of bovine serum albumin, Protein A, and rabbit IgG in solution. Measurements were performed with an impedance analyzer and dielectric cell. Protein additions to bulk solution were measured by differential dielectric relaxation spectroscopy, presented as a method to measure the individual contributions of proteins to relaxation phenomena and reduce effects of electrode polarization. Relaxation characteristics of the proteins individually and as a complex were observed. Frequency shifts in the relaxation characteristics indicate binding. This illustrates the potential use of bulk solution dielectric relaxation as the principle of operation for a biosensor.
One-way total reflection with one-dimensional magneto-optical photonic crystals
Authors: Yu Zongfu , Wang Zheng , Fan Shanhui
Published: March 2007

The authors show that one-dimensional magneto-optical photonic crystals can achieve one-way total reflection. The unit cell of the crystal, which consists of two bismuth iron garnet layers with opposite magnetization and one SiO2 layer, is designed to simultaneously break time-reversal, spatial inversion, and mirror symmetries. Such crystals are important for creating compact broadband optical isolators.
Solution-processable pentacene microcrystal arrays for high performance organic field-effect transistors
Authors: Lee Wi Hyoung , Kim Do Hwan , Jang Yunseok , Cho Jeong Ho , Hwang Minkyu , Park Yeong Don , Kim Yong Hoon , Han Jeong In , Cho Kilwon
Published: March 2007

The authors report the fabrication of one-dimensional crystal arrays of triisopropylsilylethynyl pentacene (TIPS PEN) via simple drop casting on a tilted substrate. By pinning a solution droplet on the tilted substrate, an array of ribbon-shaped crystals aligned in the tilted direction was formed on the substrate. X-ray diffraction analysis revealed that these crystals were oriented in the crystal growth direction. A thin film transistor based on such an array of TIPS PEN crystals was found to have a high field-effect mobility of 0.3cm2∕Vs, which results from the directed organization of the π-conjugated molecules.
Subsurface enrichment of Co in Si (100) at initial stages of growth at room temperature: A study by high-resolution Rutherford backscattering
Authors: Dash S. P. , Goll D. , Carstanjen H. D.
Published: March 2007

The Co distribution in the initial stages of growth of Co on Si (100) at room temperature has been probed in situ by high-resolution Rutherford backscattering spectrometry. Even at very low coverage (0.08 ML) extensive Co in-diffusion is found. The in-diffused Co forms a pronounced subsurface maximum which shifts into the Si bulk with increasing coverage and persists up to a coverage of 1.19 ML. The Co concentration at the surface saturates at the value of 0.5 for 1.19 ML of Co. Evidence of Si out-diffusion is seen for 2 and 2.93 ML which results in the formation of a CoSi phase.
Anatomy of the nasal passages of three species of Australian bats in relation to water loss
Authors: Nelson J. E. , Christian K. A. , Baudinette R. V.
Published: March 2007

A previous study found substantial variation in rates of water loss in three species of Australian bats, with the orange leafnosed bat (Rhinonycteris aurantius) having a rate more than twice that of the large bentwing bat (Miniopterus schreibersii) and the ghost bat (Macroderma gigas). Using histological sections, we examined the nasal passages of these species to determine whether any of the species have complex turbinals that may function to reduce respiratory water loss. M. schreibersii has the most complex nasal passages, and R. aurantius has the simplest. Calculations indicate that the respiratory water loss of R. aurantius and M. schreibersii are similar, but this indicates that the nasal turbinals of M. schreibersii function to conserve pulmonary water given that the metabolic rate, and therefore respiratory frequency, is higher in M. schreibersii. R. aurantius and M. gigas echolocate by emitting pulses from the nostrils whereas M. schreibersii emits pulses from the mouth. The structure of the nasal passages of nasal emitters is constrained by the demands of echolocation, and this may preclude the development of complex turbinal arrangements required for the conservation of respiratory water.
AutoSCOP: automated prediction of SCOP classifications using unique pattern-class mappings
Authors: Gewehr Jan E. , Hintermair Volker , Zimmer Ralf
Published: March 2007

Motivation: The sequence patterns contained in the available motif and hidden Markov model (HMM) databases are a valuable source of information for protein sequence annotation. For structure prediction and fold recognition purposes, we computed mappings from such pattern databases to the protein domain hierarchy given by the ASTRAL compendium and applied them to the prediction of SCOP classifications. Our aim is to make highly confident predictions also for non-trivial cases if possible and abstain from a prediction otherwise, and thus to provide a method that can be used as a first step in a pipeline of prediction methods. We describe two successful examples for such pipelines. With the AutoSCOP approach, it is possible to make predictions in a large-scale manner for many domains of the available sequences in the well-known protein sequence databases.

Results: AutoSCOP computes unique sequence patterns and pattern combinations for SCOP classifications. For instance, we assign a SCOP superfamily to a pattern found in its members whenever the pattern does not occur in any other SCOP superfamily. Especially on the fold and superfamily level, our method achieves both high sensitivity (above 93%) and high specificity (above 98%) on the difference set between two ASTRAL versions, due to being able to abstain from unreliable predictions. Further, on a harder test set filtered at low sequence identity, the combination with profile–profile alignments improves accuracy and performs comparably even to structure alignment methods. Integrating our method with structure alignment, we are able to achieve an accuracy of 99% on SCOP fold classifications on this set. In an analysis of false assignments of domains from new folds/superfamilies/families to existing SCOP classifications, AutoSCOP correctly abstains for more than 70% of the domains belonging to new folds and superfamilies, and more than 80% of the domains belonging to new families. These findings show that our approach is a useful additional filter for SCOP classification prediction of protein domains in combination with well-known methods such as profile–profile alignment.

Availability: A web server where users can input their domain sequences is available at http://www.bio.ifi.lmu.de/autoscop

Contact:  jan.gewehr@ifi.lmu.de
Dissociation of somatic growth from segmentation drives gigantism in snakes
Authors: Head Jason J , David Polly P
Published: March 2007

Body size is significantly correlated with number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that change in number of body segments produced during somitogenesis is an important factor in evolutionary change in body size, but the role of segmentation in the evolution of extreme sizes, including gigantism, has not been examined. We explored the relationship between body size and vertebral count in basal snakes that exhibit gigantism. Boids, pythonids and the typhlopid genera,TyphlopsandRhinotyphlops, possess a positive relationship between body size and vertebral count, confirming the importance of pleomerism; however, giant taxa possessed fewer than expected vertebrae, indicating that a separate process underlies the evolution of gigantism in snakes. The lack of correlation between body size and vertebral number in giant taxa demonstrates dissociation of segment production in early development from somatic growth during maturation, indicating that gigantism is achieved by modifying development at a different stage from that normally selected for changes in body size.