bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong near-field optical localization on an array of gold nanodisks
Authors: Aigouy Lionel , Prieto P. , Vitrey A. , Anguita J. , Cebollada A. , González M. U. , García-Martín A. , Labéguerie-Egéa J. , Mortier M.
Published: August 2011

By scanning near-field optical microscopy, we measured the localization of the electromagnetic field on an array of gold nanodisks illuminated in a transmission mode. We experimentally observed that the field is localized between the disks, with a pattern oriented along the incident polarization direction. We also observed that the electromagnetic field rapidly decays above the nanodisks, showing a strong vertical localization. The experimental results are in good agreement with numerical simulations performed by a finite difference time domain method. This study provides quantitative information about the local optical properties of closely-packed nanodisks that can be used for applications in biochemical sensors and nanolithography.
Epitaxial TiN(001) wetting layer for growth of thin single-crystal Cu(001)
Authors: Chawla J. S. , Zhang X. Y. , Gall D.
Published: August 2011

Single-crystal Cu(001) layers, 4-1400 nm thick, were deposited on MgO(001) with and without a 2.5-nm-thick TiN(001) buffer layer. X-ray diffraction and reflection indicate that the TiN(001) surface suppresses Cu-dewetting, yielding a 4 × lower defect density and a 9 × smaller surface roughness than if grown on MgO(001) at 25 °C. In situ and low temperature electron transport measurements indicate that ultra-thin (4 nm) Cu(001) remains continuous and exhibits partial specular scattering at the Cu-vacuum boundary with a Fuchs-Sondheimer specularity parameter p = 0.6 ± 0.2, suggesting that the use of epitaxial wetting layers is a promising approach to create low-resistivity single-crystal Cu nanoelectronic interconnects.
Magnetic field effect on spin dependent conversion of nonequilibrium Si–O chemical bonds on the Czochralski-grown Si crystal surface
Authors: Koplak O. V. , Dmitriev A. I. , Kakeshita T. , Morgunov R. B.
Published: August 2011

The magnetic field effect on the surface oxidation of Czochralski-grown Si single crystals has been observed via atomic force microscopy, electron microscopy, secondary emission ion and Auger spectroscopy, and x-ray photoelectron spectroscopy. The changes in the concentration of oxygen complexes and chemical elements on the crystal surface exposed to a magnetic field of 0.17 T are evidence of spin dependent surface reactions involving unstable intermediate Si–O–Si complexes as precursors. The experimental data have been discussed in terms of the theory of spin dependent reactions controlled by magnetic field.
Optimizing mixing in lid-driven flow designs through predictions from Eulerian indicators
Authors: McIlhany Kevin L. , Mott David , Oran Elaine , Wiggins Stephen
Published: August 2011

In this paper, we further develop the notion of Eulerian indicators (EIs) for predicting Lagrangian mixing behavior. We employ a two-dimensional “blinking” Stokes flow as a model for mixing in a three-dimensional, spatially periodic channel flow. Each blinking flow alternates two distinct velocity fields that were calculated using a lid-driven cavity model. A new EI termed mobility is introduced to measure how effectively the blinking velocity fields transport fluid throughout the domain. We also calculate the transversality for these flows, which is an EI measuring how much the velocity direction at each point in the domain changes when the velocity fields blink. For the studied flows, we show that although individually the mobility and transversality do not correlate well with mixing as measured by the decay of the variance of concentration, the product of mobility and transversality does correlate well with the decay of the variance of concentration and predicts which combinations of velocity fields will produce the most effective mixing.
Thermodynamics for non-equilibrium pattern formation
Authors: Attard Phil
Published: August 2011

The second entropy theory for non-equilibrium thermodynamics is used to show that the optimum structure or pattern of a time-dependent system corresponds to the maximum entropy. A formula for the total entropy of convective heat flow is derived. The Navier-Stokes equations in Boussinesq approximation for straight roll convection are solved by a Fourier expansion technique. Results for the velocity amplitude are in good agreement with previous computations and experimental measurements. For the spontaneous transitions between straight roll states reported in the literature, it is shown that the measured change in convective pattern wave length corresponds to an increase in the entropy.
Performance of a fisheries catch-at-age model (Stock Synthesis) in data-limited situations
Authors: Wetzel Chantell R. , Punt André E.
Published: August 2011

Limited data are a common challenge posed to fisheries stock assessment. A simulation framework was applied to examine the impact of limited data and data type on the performance of a widely used catch-at-age stock-assessment method (Stock Synthesis). The estimation method provided negatively biased estimates of current spawning-stock biomass (SSB) relative to the unfished level (final depletion) when only recent survey indices were available. Estimation of quantities of management interest (unfished SSB, virgin recruitment, target fishing mortality and final depletion) improved substantially even when only minimal-length-composition data from the survey were available. However, the estimates of some quantities (final depletion and unfished SSB) remained biased (either positively or negatively) even in the scenarios with the most data (length compositions, age compositions and survey indices). The probability of overestimating yield at the target SSB relative to the true such yield was ~50%, a risk-neutral result, for all the scenarios that included length-composition data. Our results highlight the importance of length-composition data for the performance of an age-structured assessment model, and are encouraging for the assessment of data-limited stocks.
Nanoscience with non-equilibrium plasmas at atmospheric pressure
Authors: Belmonte T , Arnoult G , Henrion G , Gries T
Published: August 2011

This review devoted to nanoscience with atmospheric-pressure plasmas shows how nanomaterials are synthesized locally using three main ways: localized plasma-enhanced chemical vapour deposition, nanoparticles and templates. On the other hand, self-organization of nano-objects on surfaces is driven by electric fields, stress and high temperatures. We show that the specificities of plasmas at high pressures, such as their small size, their self-organization or their filamentation, have been little exploited in the synthesis of nanomaterials. Finally, perspectives in the field are given.
High efficiency electrophosphorescence from bilayer organic light emitting diodes
Authors: Li Minghang , Chen Wei-Hsuan , Lin Ming-Te , Oswald Iain , Omary Mohammad , Shepherd Nigel D
Published: August 2011

An electron mobility of 2.7 × 10−5 cm2 V−1 s−1 was measured for the phosphorescent emitter bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II)(Pt(ptp)2), which prompted its evaluation as both the emissive layer and electron transport layer in organic light emitting diodes with a simple bilayer structure. Power and external quantum efficiencies of 54.0 ± 0.2 lm W−1 and 15.9% were obtained, which as far as we could ascertain are amongst the highest reported values for bilayer devices. We ascribe the high device efficiency to the combination of the high electron mobility, short excited-state lifetime (117 ns) and high luminescence quantum yield (60%) of the bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II). The colour temperature of the devices was 2855 K at 5 V, which places the emission in the ‘warm’ light spectral region.
Optical properties of ZnO/MgZnO quantum wells with graded thickness
Authors: Lv X Q , Zhang J Y , Liu W J , Hu X L , Chen M , Zhang B P
Published: August 2011

The optical properties of ZnO/Mg0.1Zn0.9O single quantum wells with graded well width were studied using temperature-dependent photoluminescence (PL) spectroscopy. The ratio of emission intensity between the well and barrier layers was found to increase monotonically when the sample temperature was increased from 78 to 210 K, indicating an efficient carrier transfer from the barrier to the well. The emission peak of the Mg0.1Zn0.9O barrier exhibited a blueshift first and then a redshift with increasing temperature, which was attributed to the repopulation of localized carriers in energy-tail states induced by alloy composition fluctuations. Such an anomalous temperature dependence of PL energy contributed to the carrier transfer. On the other hand, the emission from the well layer exhibited a transition behaviour from localized to free excitons with increasing temperature. A further analysis of the temperature-dependent emission peaks of different well widths revealed that the localization energy of excitons was related to the potential variation induced mainly by well width fluctuations. Moreover, by comparing experimental results with calculation, the separation between the quantum confinement regime and quantum-confined Stark regime was found to occur at a well width of about 3 nm.
Adult Resuscitation 2010 Guidelines Update
Authors: Service Neal , Simon Chantal
Published: August 2011

Basic or advanced adult life support is a common scenario in a hospital environment. However, adult resuscitation scenarios are an infrequent occurrence in the surgery or the community at large. The key role of the GP is to provide initial resuscitation prior to potential transfer to a secondary care centre for on going assessment and management.
Residue Dynamics Studies of Aluminum Phosphide and Magnesium Phosphide in Stored Rice Utilizing a Sulfuric Acid‐Toluene Extraction Coupled with Gas Chromatography Analysis
Authors: Zhang Fengzu , Jiang Yaping , Wang Lei , Kang Shu , Pan Canping
Published: August 2011

A method for determination of aluminum phosphide and magnesium phosphide residues in rice was developed and validated. This work, through good laboratory practices, demonstrated aluminum and magnesium phosphide residue dynamics in stored rice. Rice samples were treated with sulfuric acid, which hydrolyzed phosphides to phosphine (PH3), which was simultaneously trapped in toluene. The organic layer was filtered and then analyzed by gas chromatography with a flame photometric detector. The PH3 calibration curves showed a strong linear relationship in the range of 0.012–1.2 mg/L, with a correlation coefficient of 0.999. The limit of detection of this method was 0.004 mg/kg. The average recoveries from samples fortified with aluminum phosphide and magnesium phosphide ranged from 76.8 to 106.5% with relative standard deviations below 10.2% (n = 5). PH3 was applied separately to rice samples to study dissipation dynamics at application dosages of 9.0 and 12 g/m3, respectively. The results showed half‐lives of aluminum and magnesium phosphide in rice to be 1.84 and 1.53 days, respectively. PH3 was applied once at low and high dosages. The low dosage was 4.5 g/m3 of aluminum phosphide and 6.0 g/m3 of magnesium phosphide, and the high dosage was 9.0 and 12 g/m3 for these two formulations, respectively. The final PH3 residues were below 0.013 mg/kg (limit of quantification).
Effect of Temperature on Cortical Infection by Plasmodiophora brassicae and Clubroot Severity
Authors: Sharma Kalpana , Gossen Bruce D. , McDonald Mary Ruth
Published: August 2011

A study was conducted to assess the effect of temperature on infection and development of Plasmodiophora brassicae in the root cortex of Shanghai pak choy (Brassica rapa subsp. chinensis) and on subsequent clubroot severity. Ten-day-old seedlings were grown individually, inoculated with resting spores, and maintained in growth cabinets at 10, 15, 20, 25, and 30°C. Seedlings were harvested at 2-day intervals, starting 8 days after inoculation (DAI) and continuing until 42 DAI. Roots were assessed at 4-day intervals for the incidence of cortical infection and stage of infection (young plasmodia, mature plasmodia, and resting spores), at 2-day intervals for symptom development and clubroot severity, and at 8-day intervals for the number of spores per gram of gall. Temperature affected every stage of clubroot development. Cortical infection was highest and symptoms were observed earliest at 25°C, intermediate at 20 and 30°C, and lowest and latest at 15°C. No cortical infection or symptoms were observed at 42 DAI in plants grown at 10°C. A substantial delay in the development of the pathogen was observed at 15°C. Resting spores were first observed at 38 DAI in plants at 15°C, 26 DAI at 20 and 30°C, and 22 DAI at 25°C. The yield of resting spores from galls was higher in galls that developed at 20 to 30°C than those that developed at 15°C over 42 days of assessment. These results support the observation in companion studies that cool temperatures result in slower development of clubroot symptoms in brassica crops, and demonstrate that the temperature has a consistent pattern of effect throughout the life cycle of the pathogen.
Defence strategies against a parasitoid wasp in
Drosophila
: fight or flight?
Authors: Lefèvre Thierry , de Roode Jacobus C. , Kacsoh Balint Z. , Schlenke Todd A.
Published: August 2011

Hosts may defend themselves against parasitism through a wide variety of defence mechanisms, but due to finite resources, investment in one defence mechanism may trade-off with investment in another mechanism. We studied resistance strategies against the parasitoid wasp
Leptopilina boulardi
in two
Drosophila
species. We found that
D. melanogaster
had significantly lower physiological resistance against
L. boulardi
than
D. simulans
, and hypothesized that
D. melanogaster
might instead invest more heavily in other forms of defence, such as behavioural defence. We found that when given a choice between clean oviposition sites and sites infested with wasps, both
D. melanogaster
and
D. simulans
detected and avoided infested sites, which presumably limits later exposure of their offspring to infection. Unlike
D. simulans
, however,
D. melanogaster
laid significantly fewer eggs than controls in the forced presence of wasps. Our findings suggest that
D. melanogaster
relies more heavily on behavioural avoidance as defence against wasp parasitism than
D. simulans
, and that this may compensate for a lack of physiological defence.
Cryoprotection–lyophilization and physical stabilization of rifampicin-loaded flower-like polymeric micelles
Authors: Moretton Marcela A. , Chiappetta Diego A. , Sosnik Alejandro
Published: August 2011

Rifampicin-loaded poly(
ε
-caprolactone)–
b
-poly(ethylene glycol)–poly(
ε
-caprolactone) flower-like polymeric micelles display low aqueous physical stability over time and undergo substantial secondary aggregation. To improve their physical stability, the lyoprotection–lyophilization process was thoroughly characterized. The preliminary cryoprotectant performance of mono- and disaccharides (e.g. maltose, glucose), hydroxypropyl-β-cyclodextrin (HPβCD) and poly(ethylene glycol) (PEG) of different molecular weights was assessed in freeze–thawing assays at −20°C, −80°C and −196°C. The size and size distribution of the micelles at the different stages were measured by dynamic light scattering (DLS). A cryoprotectant factor (
f
c
) was determined by taking the ratio between the size immediately after the addition of the cryoprotectant and the size after the preliminary freeze–thawing assay. The benefit of a synergistic cryoprotection by means of saccharide/PEG mixtures was also assessed. Glucose (1 : 20), maltose (1 : 20), HPβCD (1 : 5) and glucose or maltose mixtures with PEG3350 (1 : 20) (copolymer:cryoprotectant weight ratio) were the most effective systems to protect 1 per cent micellar systems. Conversely, only HPβCD (1 : 5) cryoprotected more concentrated drug-loaded micelles (4% and 6%). Then, those micelle/cryoprotectant systems that displayed
f
c
values smaller than 2 were freeze-dried. The morphology of freeze-dried powders was characterized by scanning electron microscopy and atomic force microscopy and the residual water content analysed by the Karl Fisher method. The HPβCD-added lyophilisates were brittle porous cakes (residual water was between 0.8% and 3%), easily redispersable in water to form transparent systems with a minimal increase in the micellar size, as determined by DLS.
The global spread of drug-resistant influenza
Authors: Chao Dennis L. , Bloom Jesse D. , Kochin Beth F. , Antia Rustom , Longini Ira M.
Published: August 2011

Resistance to oseltamivir, the most widely used influenza antiviral drug, spread to fixation in seasonal influenza A(H1N1) between 2006 and 2009. This sudden rise in resistance seemed puzzling given the low overall level of the oseltamivir usage and the lack of a correlation between local rates of resistance and oseltamivir usage. We used a stochastic simulation model and deterministic approximations to examine how such events can occur, and in particular to determine how the rate of fixation of the resistant strain depends both on its fitness in untreated hosts as well as the frequency of antiviral treatment. We found that, for the levels of antiviral usage in the population, the resistant strain will eventually spread to fixation, if it is not attenuated in transmissibility relative to the drug-sensitive strain, but not at the speed observed in seasonal H1N1. The extreme speed with which the resistance spread in seasonal H1N1 suggests that the resistant strain had a transmission advantage in untreated hosts, and this could have arisen from genetic hitchhiking, or from the mutations responsible for resistance and compensation. Importantly, our model also shows that resistant virus will fail to spread if it is even slightly less transmissible than its sensitive counterpart—a finding of relevance given that resistant pandemic influenza (H1N1) 2009 may currently suffer from a small, but nonetheless experimentally perceptible reduction in transmissibility.
On the calculation of an attenuation coefficient for transects of ice-covered ocean
Authors: Bennetts Luke G. , Squire Vernon A.
Published: August 2011

Exponential attenuation of ocean surface waves in ice-covered regions of the polar seas is modelled in a two-dimensional, linear setting, assuming that the sea ice behaves as a thin-elastic plate. Attenuation is produced by natural features in the ice cover, with three types considered: floes, cracks and pressure ridges. An inelastic damping parameterization is also incorporated. Efficient methods for obtaining an attenuation coefficient for each class of feature, involving an investigation of wave interaction theory and averaging methods, are sought. It is found that (i) the attenuation produced by long floes can be obtained from the scattering properties of a single ice edge; and (ii) wave interaction theory in ice-covered regions requires evanescent and damped-propagating motions to be included when scattering sources are relatively nearby. Implications for the integration of this model into an oceanic general circulation model are also discussed.
Biogeography of avian blood parasites (Leucocytozoon spp.) in two resident hosts across Europe: phylogeographic structuring or the abundance–occupancy relationship?
Authors: JENKINS TANIA , OWENS IAN P. F.
Published: August 2011

Relationships between hosts and parasites represent complex co‐evolving systems that can vary both temporally and spatially. This variation may result in different phylogeographic outcomes, ranging from highly geographically structured parasite populations comprised of specialist lineages that are locally abundant but have restricted global occupancy to geographically unstructured parasite populations consisting of widespread parasites. Here, we present results from a large biogeographic study of the Leucocytozoon blood parasites of two nonmigrant bird species, conducted at nine sites across Europe. The aim was to determine whether the parasite lineages of the two hosts were phylogeographically structured across Europe. Employing molecular methods, we found a large diversity of parasites, and although overall prevalence varied greatly, the parasites were not genetically structured. Several measures of local parasite abundance were associated with the number of sites that the lineage occurred in, which is consistent with the macroecological phenomenon of the abundance–occupancy relationship. Taken together, our results show that parasite dispersal is somewhat uncoupled to that of the host in this system: we suggest that broad host and/or vector preference may play an important role in determining the distribution of these parasites and in affecting host–parasite coevolution in this system.
Peroxidase Activity after Viral Infection and Whitefly Infestation in Juvenile and Mature Leaves of Solanum lycopersicum
Authors: Dieng Hamady , Satho Tomomitsu , Hassan Ahmad Abu , Aziz Al Thbiani , Morales Ronald Enrique , Hamid Suhaila Ab , Miake Fumio , Abubakar Sazaly
Published: August 2011

Whitefly infestation and the begomoviruses that they transmit have been shown to affect the activities of plant defence proteins, but with no relation to heterophylly, a process of great importance underlying the overall biology of plants. Here, we have assessed the effects of Tomato yellow leaf curl virus (TYLCV) infection on Solanum lycopersicum peroxidase (POD) activity and have examined whether leaves of different ages exhibit differential POD activity in response to infection and infestation with Bemisia tabaci B biotype. We used leaf discs of two ages (juvenile and mature) with two different infection statuses (infected and healthy) to examine the activity of the tomato plant peroxidase using guaiacol as a substrate and taking exposure time into account. S. lycopersicum showed increased POD activity in the presence of TYLCV. The activity of the enzyme was higher in mature than in juvenile leaves. In general, both infected and healthy leaves exhibited greater POD activity during whitefly infestation. In the infested juvenile leaves, POD activity was much lower in the healthy leaves and increased gradually with period of exposure to B. tabaci B infestation. In contrast, the activity of the enzyme remained low in infested mature leaves in both the presence and absence of the virus even with increased exposure time. Determination of the distribution of an insect pest is critical for sampling and management. Leaf age is presumed to be associated with the within‐host distribution of the geminivirus vector B. tabaci. Juvenile leaves will usually attract more insects due to increased nutritional value and weaker defences. Our results highlight the importance of leaf age/position on the whitefly – host plant – geminivirus interactions and have important implications for sampling and control strategies.
Age, sun and substrate: triggers of bacterial communities in lichens
Authors: Cardinale Massimiliano , Steinová Jana , Rabensteiner Johannes , Berg Gabriele , Grube Martin
Published: August 2011

Bacterial communities colonize the surfaces of lichens in a biofilm‐like manner. The overall structure of the bacterial communities harboured by the lichens shows similarities, in particular the dominance of not yet cultured Alphaproteobacteria. Parameters causing variation in abundance, composition and spatial organization of the lichen‐associated bacterial communities are so far poorly understood. As a first step, we used a microscopic approach to test the significance of both lichen‐intrinsic and extrinsic environmental factors on the bacterial communities associated with 11 lichen samples, belonging to six species. Some of these species have thalli with a distinct age gradient. A statistically significant effect can be attributed to the age of the thallus parts, which is an intrinsic factor: growing parts of the lichens host bacterial communities that significantly differ from those of the ageing portions of the thalli. The substrate type (rock, tree, understory) and (at a lower extent) the exposition to the sun also affected the bacterial communities. Interestingly, the abundance of bacterial cells in the lichens was also influenced by the same structure‐triggering factors. No effect on the composition with main bacterial groups was attributed to different lichen species, differentiated thallus parts or thallus growth type. Our results are important for the experimental designs in lichen‐bacterial ecology.
Collision tumour affecting the paranasal sinuses of a geriatric donkey
Authors: Witte S. , Mueller P. O. E. , Kosarek C. , Webb J. L. , Howerth E. W.
Published: August 2011

Tumours of the paranasal sinuses are relatively uncommon in the horse. A collision tumour occurs when 2 separate tumour types arise in close proximity to each other and encroach on one another. This report describes the presence of neoplasia comprising glandular tissue and spindle cells growing concurrently in the frontal and caudal maxillary sinus of a geriatric donkey. As far as the authors are aware, this is the first description of a possible collision tumour in an equid.
Remarks on endomorphisms and rational points
Authors: Amerik E. , Bogomolov F. , Rovinsky M.
Published: August 2011

Let X be an algebraic variety and let f:X−−→X be a rational self-map with a fixed point q, where everything is defined over a number field K. We make some general remarks concerning the possibility of using the behaviour of f near q to produce many rational points on X. As an application, we give a simplified proof of the potential density of rational points on the variety of lines of a cubic fourfold, originally proved by Claire Voisin and the first author in 2007.
Computational Fluid Dynamics and Experimental Validations of the Direct Coupling Between Interior, Intermediate and Exterior Ballistics Using the Euler Equations
Authors: Cayzac Roxan , Carette Eric , Alziary de Roquefort Thierry , Renard François-Xavier , Roux Dominique , Balbo Patrick , Patry Jean-Noël
Published: August 2011

For several years we have been working on the development of a computational fluid dynamics ballistics code called FREIN. This code is the result of a strong cooperation between Nexter Munitions and the University of Poitiers. In the last years, efforts have been carried out to improve the 3D modeling. In a fully unsteady way, the interior, intermediate and exterior ballistics were modeled as well as the weapon system environment. The complex phenomena encountered are investigated by an adapted numerical simulation approach using the Euler equations for two immiscible gases. The method involves moving bodies with respect to fixed Cartesian meshes and the aerodynamic forces are used to compute the trajectories. In this paper, theoretical developments and computations have been applied mainly to the simulation of the firing of an advanced 120 mm lightweight tank demonstrator. In comparison with firing experiments, first computation validation results concerning interior ballistics, muzzle brake flow, sabot discard and blast wave propagation and reflection are presented and are very satisfactory.
Investigation of Stress Intensity Factors for an Interface Crack in Multi-Interface Materials Using an Interaction Integral Method
Authors: Wu Linzhi , Yu Hongjun , Guo Licheng , He Qilin , Du Shanyi
Published: August 2011

A new interaction integral formulation is derived for obtaining mixed-mode stress intensity factors (SIFs) of an interface crack with the tip close to complicated material interfaces. The method is a conservation integral that relies on two admissible mechanical states (actual and auxiliary fields). By a suitable selection of the auxiliary fields, the domain formulation does not contain any integral related to the material interfaces, which makes it quite convenient to deal with complicated interface problems. The numerical implementation of the derived expression is combined with the extended finite element method (XFEM). According to the numerical calculations, the interaction integral shows good accuracy for straight and curved interface crack problems and exhibits domain-independence for material interfaces. Finally, an interfacial fracture problem is investigated for the representative centrosymmetric structure formed by two constituent materials.
Lotus Effect Toy
Authors: Shakerin Said
Published: August 2011

This is a short article about Aqua Drop, a toy that employs a superhydrophobic surface. After defining superhydrophobic surface, its occurrence in nature, and its importance in science and technology, I describe the toy, followed by several student activities that can be performed with the toy and easily found natural objects.
Wikis as a Teaching Tool in Physics Classrooms
Authors: Mohottala Hashini E.
Published: August 2011

The advances of the digital age have made the duty and responsibility of the professor more complex and involved. The Internet has made powerful and useful tools available to us to disseminate knowledge in an interesting and effective manner. In this article, I discuss one such tool: Wikispaces (wikis)—a set of interactive web pages that can be accessed and updated by a group of users using any web browser.1
Flight Physics for Beginners: Simple Examples of Applying Newton's Laws
Authors: Spathopoulos Vassilis
Published: August 2011

Educators are constantly trying to find new ways of motivating their students. In subjects such as mechanics with a strong mathematical component, it is particularly important to devise real-life examples that can increase interest and student excitement. Aircraft flight is a topic that most young people find exciting. It therefore would seem reasonable to incorporate applications from the world of flight into an introductory physics course.
Acyclovir is a substrate for the human breast cancer resistance protein (BCRP/ABCG2): implications for renal tubular transport and acyclovir-induced nephrotoxicity
Authors: Gunness Patrina , Aleksa Katarina , Koren Gideon
Published: August 2011

The human breast cancer resistance protein (BCRP/ABCG2) is widely expressed in human tissues, including the kidney. In mice, Bcrp1 (murine BCRP ortholog) mediates the transport of acyclovir into breast milk. It is plausible that acyclovir is also a substrate for the human BCRP. The objective of the study was to determine whether acyclovir is a substrate for human BCRP. Transfected human embryonic kidney (HEK293) cells (containing the wild-type ABCG2 gene) were exposed to [8-14C]acyclovir (1 µmol/L) in the presence or absence of the BCRP inhibitor fumitremorgin C (FTC). Intracellular acyclovir accumulation was assessed using a liquid scintillation counter. Coexposure to FTC resulted in a significant (5-fold) increase in the intracellular accumulation of acyclovir. The results suggest that acyclovir is a substrate for human BCRP. The study is the first to provide direct evidence for the role of human BCRP in acyclovir transport and its potential significance with respect to renal tubular transport of acyclovir and the direct renal tubular insult induced by the drug.
Impairment of endothelial protection by ischemic postconditioning in patients with major depressive disorder
Authors: Zhuo Chuanjun , Wang Ying , Tian Hongjun , Wang Xiaohui , Chen Yuhui , Mao Fuqiang
Published: August 2011

This study used a model of ischemia–reperfusion injury to the brachial artery endothelium to investigate whether the protective role of ischemic postconditioning (IPostC) is impaired in patients with major depressive episode. Flow-mediated dilation (FMD) was measured before and after ischemia–reperfusion in the absence or presence of IPostC in 24 patients with major depressive disorder and 20 healthy controls. In addition, the severity of the depression, as assessed by the Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI) scores, and plasma nitrogen dioxide (NOx) levels were also determined. Ischemia–reperfusion resulted in a significant decrease in FMD in both patients with a major depressive episode and healthy controls. IPostC effectively prevented this decrease in FMD in healthy controls, but not in patients with a major depressive episode. HDRS and BDI scores were markedly increased, but plasma NOx levels decreased, in patients with a major depressive episode compared with those in healthy controls. Correlation analysis showed that HDRS and BDI scores and plasma NOx levels were significantly associated with post-ischemia–reperfusion FMD. These results suggest that endothelial protection by IPostC is impaired in patients with major depressive disorder, which may be related to the decrease in endothelial nitric oxide production and the severity of the depression.
ANALYSIS OF MAGNETIC CRITICAL FIELDS IN IRON-BASED SmFeAsO0.85 HIGH-Tc SUPERCONDUCTOR
Authors: AHMAD DAWOOD , SONG TAE KWON , PARK IN SUK , KIM G. C. , REN ZHI-AN , KIM Y. C.
Published: August 2011

The magnetic properties of the newly discovered iron-oxypnictide SmFeAsO 0.85 high-Tc superconductor with a Tc of around 55 K were investigated. Bulk SmFeAsO 0.85 was prepared by a method for high-pressure synthesis. The lower critical field H c1 was estimated from the magnetization at low fields; H c1 (0) was measured to be 212 Oe. A linear temperature dependence instead of saturation at low temperatures in H c1 (T) revealed unconventional superconductivity with a nodal gap structure in our SmFeAsO 0.85 superconductor. The results showed that the well-known secondary peak in the temperature dependence of the critical current density Jc is absent in the SmFeAsO 0.85 high-Tc superconductor. The irreversibility line B irr was fitted well by the power law dependence (1 - T/Tc)n with n ~ 1.5. This is indicative of the flux creep phenomena in the SmFeAsO 0.85 high-Tc superconductor. In addition, within the range of measurement temperatures in this study, no crossover was observed in the temperature dependence of the irreversibility line B irr which may be due to low anisotropy in our SmFeAsO 0.85 superconductor.
DESIGN OF HIGH EFFICIENCY AND LARGE SEPARATING ANGLE BEAM SPLITTER BASED ON PHOTONIC CRYSTAL CAVITY RESONATOR
Authors: GUO HAO , LIAO QINGHUA , YU TIANBAO , CHEN SHUWEN , HUANG YONGZHEN
Published: August 2011

We present the design and simulation of an ultracompact high efficiency beam splitter based on propagation properties of the light waves in waveguide and cavity resonator. The splitting properties of the beam splitter have been numerically simulated and analyzed using the plane wave expansion (PWE) method and finite difference time domain (FDTD) method. Then in order to minimize backward reflections and to obtain equal distribution of power, we placed a cavity resonator waveguides to optimize the devices. It is shown that a beam splitter with high efficiency and large separating angle for TM mode can be achieved. There is no doubt that these excellent features will provide the structure a promising applying prospect for photonic integrated circuit.
Covalent phthalocyanine-fullerene dyads: synthesis, electron transfer in solutions and molecular films
Authors: Tkachenko Nikolai V. , Efimov Alexander , Lemmetyinen Helge
Published: August 2011

Phthalocyanine-fullerene dyads have being under intensive development and investigation during past decade. Strong absorption of the phthalocyanine chromophore in the red part of the spectrum and ability of the dyad to perform efficient photoinduced charge transfer in non-polar media make them particularly attractive for organic optoelectronic applications. This microreview will focus on covalently linked phthalocyanine-fullerene conjugates in solutions and solid nanostructures. The covalent bonding enables sufficient degree of control over mutual organization of the donor and acceptor parts, and makes possible to investigate the relationships between molecular structure and functioning of single molecules and molecular assemblies.
Hyperglucagonemia precedes a decline in insulin secretion and causes hyperglycemia in chronically glucose-infused rats
Authors: Jamison Rachel A. , Stark Romana , Dong Jianying , Yonemitsu Shin , Zhang Dongyan , Shulman Gerald I. , Kibbey Richard G.
Published: August 2011

Islet damage from glucose toxicity is implicated in the pathogenesis of type 2 diabetes, but the sequence of events leading to islet cell dysfunction and hyperglycemia remains unclear. To examine the early stages of islet pathology resulting from increased basal glucose loads, normal awake rats were infused with glucose continuously for 10 days. Plasma glucose and markers of islet and liver function were monitored throughout the infusion. After initial hyperglycemia, rats adapted to the infusion and maintained euglycemia for approximately 4 days. Continued infusion led to worsening hyperglycemia in just 5% of rats after 6 days, but 69% after 8 days and 89% after 10 days, despite unchanged basal and stimulated plasma insulin and C-peptide concentrations. In contrast, plasma glucagon concentrations increased fivefold. Endogenous glucose production (EGP) was appropriately suppressed after 4 days (2.8 ± 0.7 vs. 6.1 ± 0.4 mg·kg−1·min−1on day 0, P < 0.001) but tripled between days 4 and 8 (9.9 ± 1.7 mg·kg−1·min−1, P < 0.01). Surprisingly, the increase in EGP was accompanied by increased mitochondrial phospho enolpyruvate carboxykinase expression with appropriate suppression of the cytosolic isoform. Infusion of anti-glucagon antibodies normalized plasma glucose to levels identical to those on day 4 and ∼300 mg/dl lower than controls. This improved glycemia was associated with a 60% reduction in EGP. These data support the novel concept that glucose toxicity may first manifest as α-cell dysfunction prior to any measurable deficit in insulin secretion. Such hyperglucagonemia could lead to excessive glucose production overwhelming the capacity of the β-cell to maintain glucose homeostasis.
The Paradox of Feline Coronavirus Pathogenesis: A Review
Authors: Myrrha Luciana Wanderley , Silva Fernanda Miquelitto Figueira , Peternelli Ethel Fernandes de Oliveira , Junior Abelardo Silva , Resende Maurício , Almeida Márcia Rogéria de
Published: August 2011

Feline coronavirus (FCoV) is an enveloped single-stranded RNA virus, of the familyCoronaviridaeand the orderNidovirales. FCoV is an important pathogen of wild and domestic cats and can cause a mild or apparently symptomless enteric infection, especially in kittens. FCoV is also associated with a lethal, systemic disease known as feline infectious peritonitis (FIP). Although the precise cause of FIP pathogenesis remains unclear, some hypotheses have been suggested. In this review we present results from different FCoV studies and attempt to elucidate existing theories on the pathogenesis of FCoV infection.
A Review of Polarization Dependence Applications for Asymmetric Waveguides Vertical Couplers in Compound Semiconductor Indium Phosphide
Authors: Lee Chee-Wei
Published: August 2011

This paper reviews and presents a coherent approach to the design of compact vertical coupler (VC) in InP-based compound semiconductor with variable polarization dependence. As a polarization-independent (PI) coupler, the VC is shown to transfer light with more than 90% efficiency for both transverse-electric (TE) and transverse-magnetic (TM) polarizations. As a polarization-mode splitter (PMS), the VC is shown to preferentially couple TE or TM modes with a contrast ratio of up to 20 dB. We further demonstrate the single-mesa VC, which simplifies the fabrication process and potentially could improve the process yield, and its integration with a multimode interferometer (MMI). The versatility makes the VC a compact and useful input-stage device that not only maximizes input/output coupling efficiency to small active devices but also provides a degree of polarization control before the actual device.
Linear Hyperbolic Functional‐Differential Equations with Essentially Bounded Right‐Hand Side
Authors: Domoshnitsky Alexander , Lomtatidze Alexander , Maghakyan Abraham , Šremr Jiří
Published: August 2011

Theorems on the unique solvability and nonnegativity of solutions to the characteristic initial value problem u(1,1)(t, x) = ℓ0(u)(t, x) + ℓ1(u(1,0))(t, x) + ℓ2(u(0,1))(t, x) + q(t, x), u(t, c) = α(t) for
t ∈ [a, b],  u(a, x) = β(x)   for  x ∈ [c, d] given on the rectangle [a, b]×[c, d] are established, where the linear operators ℓ0, ℓ1, ℓ2 map suitable function spaces into the space of essentially bounded functions. General results are applied to the hyperbolic equations with essentially bounded coefficients and argument deviations.
Human Liver Cells Expressing Albumin and Mesenchymal Characteristics Give Rise to Insulin-Producing Cells
Authors: Meivar-Levy Irit , Sapir Tamar , Berneman Dana , Weissbach Tal , Polak-Charcon Sylvie , Ravassard Philippe , Tzakis Andreas G. , Mor Eytan , Ricordi Camillo , Ferber Sarah
Published: August 2011

Activation of the pancreatic lineage in the liver has been suggested as a potential autologous cell replacement therapy for diabetic patients. Transcription factors-induced liver-to-pancreas reprogramming has been demonstrated in numerous species bothin vivoandin vitro. However, human-derived liver cells capable of acquiring the alternate pancreatic repertoire have never been characterized. It is yet unknown whether hepatic-like stem cells or rather adult liver cells give rise to insulin-producing cells. Using anin vitroexperimental system, we demonstrate that proliferating adherent human liver cells acquire mesenchymal-like characteristics and a considerable level of cellular plasticity. However, using a lineage-tracing approach, we demonstrate that insulin-producing cells are primarily generated in cells enriched for adult hepatic markers that coexpress both albumin and mesenchymal markers. Taken together, our data suggest that adult human hepatic tissue retains a substantial level of developmental plasticity, which could be exploited in regenerative medicine approaches.
Shortening and Improving the Embryonic Stem Cell Test through the Use of Gene Biomarkers of Differentiation
Authors: Romero Andrea C. , Vilanova Eugenio , Sogorb Miguel A.
Published: August 2011

The embryonic Stem cell Test (EST) is a validated assay for testing embryotoxicityin vitro. The total duration of this protocol is 10 days, and its main end-point is based on histological determinations. It is suggested that improvements on EST must be focused toward molecular end-points and, if possible, to reduce the total assay duration. Five days of exposure of D3 cells in monolayers under spontaneous differentiation to 50 ng/mL of the strong embryotoxic 5-fluorouracil or to 75 μg/mL of the weak embryotoxic 5,5-diphenylhydeantoin caused between 20 and 74% of reductions in the expression of the following genes:Pnpla6,Afp,Hdac7,Vegfa, andNes. The exposure to 1 mg/mL of nonembryotoxic saccharin only caused statistically significant reductions in the expression ofNes. These exposures reduced cell viability of D3 cells by 15, 28, and 34%. We applied these records to the mathematical discriminating function of the EST method to find that this approach is able to correctly predict the embryotoxicity of all three above-mentioned chemicals. Therefore, this work proposes the possibility of improve EST by reducing its total duration and by introducing gene expression as biomarker of differentiation, which might be very interesting forin vitrorisk assessment embryotoxicity.
Swimming Exercise in the Acute or Late Phase after Sciatic Nerve Crush Accelerates Nerve Regeneration
Authors: Teodori Rosana Macher , Betini Joice , de Oliveira Larissa Salgado , Sobral Luciane Lobato , Takeda Sibele Yoko Mattozo , Montebelo Maria Imaculada de Lima
Published: August 2011

There is no consensus about the best time to start exercise after peripheral nerve injury. We evaluated the morphological and functional characteristics of the sciatic nerves of rats that began to swim immediately after crush nerve injury (CS1), those that began to swim 14 days after injury (CS14), injured rats not submitted to swimming (C), and uninjured rats submitted to swimming (S). After 30 days the number of axons in CS1 and CS14 was lower than in C (P<0.01). The diameter of axons and nerve fibers was larger in CS1 (P<0.01) and CS14 (P<0.05) than in C, and myelin sheath thickness was lower in all crushed groups (P<0.05). There was no functional difference between CS1 and CS14 (P>0.05). Swimming exercise applied during the acute or late phase of nerve injury accelerated nerve regeneration and synaptic elimination after axonotmesis, suggesting that exercise may be initiated immediately after injury.
The Cesáro Core of Double Sequences
Authors: Kayaduman Kuddusi , Çakan Celal
Published: August 2011

We have characterized a new type of core for double sequences, PC‐core, and determined the necessary and sufficient conditions on a four‐dimensional matrix A to yield PC‐core{Ax}⊆α(P‐core{x}) for all .
Two Quarantine Models on the Attack of Malicious Objects in Computer Network
Authors: Mishra Bimal Kumar , Singh Aditya Kumar
Published: August 2011

SEIQR (Susceptible, Exposed, Infectious, Quarantined, and Recovered) models for the transmission of malicious objects with simple mass action incidence and standard incidence rate in computer network are formulated. Threshold, equilibrium, and their stability are discussed for the simple mass action incidence and standard incidence rate. Global stability and asymptotic stability of endemic equilibrium for simple mass action incidence have been shown. With the help of Poincare Bendixson Property, asymptotic stability of endemic equilibrium for standard incidence rate has been shown. Numerical methods have been used to solve and simulate the system of differential equations. The effect of quarantine on recovered nodes is analyzed. We have also analyzed the behavior of the susceptible, exposed, infected, quarantine, and recovered nodes in the computer network.
Uncaria tomentosafor Reducing Side Effects Caused by Chemotherapy in CRC Patients: Clinical Trial
Authors: Farias I. L. G. , Araújo M. C. S. , Farias J. G. , Rossato L. V. , Elsenbach L. I. , Dalmora S. L. , Flores N. M. P. , Durigon M. , Cruz I. B. M. , Morsch V. M. , Schetinger M. R. C.
Published: August 2011

To evaluate the effectiveness ofUncaria tomentosain minimizing the side effects of chemotherapy and improving the antioxidant status of colorectal cancer (CRC) patients, a randomized clinical trial was conducted. Patients (43) undergoing adjuvant/palliative chemotherapy with 5-Fluorouracil/leucovorin + oxaliplatin (FOLFOX4) were split into two groups: the UT group received chemotherapy plus 300 mg ofUncaria tomentosadaily and the C group received only FOLFOX4 and served as a control. Blood samples were collected before each of the 6 cycles of chemotherapy, and hemograms, oxidative stress, enzymes antioxidants, immunologic parameters, and adverse events were analyzed. The use of 300 mg ofUncaria tomentosadaily during 6 cycles of FOLFOX4 did not change the analyzed parameters, and no toxic effects were observed.