bluuebunny/crossref_metadata_2025 huggingface dataset:
Interatrial communication through the mouth of the coronary sinus
Authors: Knauth Alison , McCarthy Karen P. , Webb Sandra , Ho Siew Yen , Allwork Sally P. , Cook Andrew C. , Anderson Robert H.
Published: July 2009

Objectives: We describe the structure of, and suggest an etiology for, the interatrial communication which can occur through the mouth of the coronary sinus. Based on the study of human embryos, we propose that the defect is best explained by dissolution of the wall of the coronary sinus adjacent to the left atrium, permitting shunting between the atriums through the right atrial orifice of the sinus. Background: An interatrial communication across the mouth of the coronary sinus defect was first described in 1965 by Raghib and colleagues, its existence being predicated on the basis of incomplete formation of the left “atriovenous fold”. Their hypothesis implies that the coronary sinus never develops, and thus the atrial septum itself is incomplete. Methods: We have studied the development of the coronary sinus in a series of human embryos. Based on this work, we present the anatomical findings in 6 specimens with varying degrees of dissolution of the walls of the coronary sinus, and ten specimens with isomerism of the right atrial appendages, in which the sinus has never been formed. Results: The coronary sinus defect is not a hole within the atrial septum, but a communication between the atriums through the mouth of the sinus. There was a range of defects in our series of specimens with usual atrial arrangement, extending from complete absence of the walls which normally separate the coronary sinus from the left atrium, to small fenestrations between this vessel and the left atrial cavity. In the hearts with isomerism of the right atrial appendages, however, we never observed an orifice of the coronary sinus. Thus, a coronary sinus defect cannot exist in this setting. Conclusions: Our findings indicate that the defect requires initial formation of the walls of the coronary sinus, but with subsequent dissolution of the wall adjacent to the left atrium. This produces a communication between the atriums through the mouth of the sinus.
Twisted atrioventricular valves in double inlet left ventricle
Authors: Mori Kazuhiro , Harada Masafumi , Kuroda Yasuhiro
Published: July 2009

Twisted atrioventricular connections usually occur in hearts with biventricular artioventricular connections. Here, we describe a case of twisted atrioventricular valves associated with double inlet left ventricle and discordant ventriculo-arterial connections. Color Doppler echocardiography, and cine magnetic resonance imaging, clearly demonstrated that the right atrioventricular valve was located anterior and superior to the left atrioventricular valve, and that the axes of the two atrioventricular valves crossed each other within the dominant left ventricle.
Screening barnyard millet germplasm against grain smut (Ustilago panici-frumentacei Brefeld)
Authors: Gupta Arun , Joshi Deeksha , Mahajan Vinay , Gupta H. S.
Published: July 2009

Barnyard millet accessions (257) were inoculated with grain smut spores at anthesis stage during 2003. Seed produced on inoculated ear heads was sown in 2005 and resulting plants evaluated for ten morphological traits and grain smut incidence. The accessions were grouped into seven groups based on origin. The lowest mean grain smut incidence was recorded for advance breeding lines, while highest mean value was observed for Uttarakhand group. Genes determining grain yield and susceptibility to grain smut were at most loosely linked as evidenced by non-significant correlations between grain smut incidence and grain yield in six out of seven groups as well as whole collection. Smut resistance along with grain yield in barnyard millet can be enhanced by adopting proper breeding strategy; therefore, in segregating generations, selection should be carried out for both characters simultaneously.
Estimating organic premiums in the US fluid milk market
Authors: Smith T.A. , Huang C.L. , Lin B.-H.
Published: July 2009

Using actual retail purchases from the 2006 Nielsen Homescan panel data, we estimate a hedonic model on price premiums and discounts associated with household characteristics, market factors, and product attributes focusing on the organic attribute for fluid milk. The organic attribute carries a significant price premium, which is largest of all product attributes considered in this study. Further, additional price variations among organic milk are observed for differences in fat content, container size and branding. Specifically, the results suggest that organic price premiums for half-gallon milk range from $1.23 for whole private label organic milk (60–68% above conventional counterpart) to $1.86 for nonfat/skim-branded organic milk (89–109% above conventional counterpart). The study also found that milk sold in a discount store (i.e., supercenter or club warehouse) was price 13 cents per half gallon, or 7.4%, below milk sold through other venues, and that milk on sale was priced 26 cents per half gallon, or 14.3%, less than the regular average price. Although household characteristics exert little influence on price relative to product attributes and market factors, the study does find that unmarried households and those with children under six pay slightly higher prices for milk, possibly due to time constraints.
Development of an objective‐oriented groundwater model for conjunctive‐use planning of surface water and groundwater
Authors: Chiu Yung‐Chia , Sun Ne‐Zheng , Nishikawa Tracy , Yeh William W.‐G.
Published: July 2009

In this paper we construct an objective‐oriented model for conjunctive‐use planning of surface water and groundwater for the Warren groundwater basin in southern California. The goal of conjunctive‐use planning is to decrease high‐nitrate concentration while maintaining groundwater levels at desired elevations and meeting water demand. We formulate a management problem that minimizes the total cost over the proper choices of the time‐varying pumping and recharge rates at prespecified wells and surface ponds. To make the solution of the management problem reliable, we must have an accurate simulation model to predict groundwater level and nitrate concentration distributions under different management alternatives. The objective‐oriented model construction approach seeks a representative parameter that has the simplest structure and requires the minimum data for identification but can produce reliable results for a given model application. With the data from the Warren groundwater basin, we show how to incorporate management objectives into the construction of an objective‐oriented model, identify the parameter structure and its corresponding parameter values, solve the generalized inverse problem effectively by finding the worst‐case parameter (WCP), evaluate the sufficiency of existing data, and find a robust experiment design when the existing data are insufficient. Results of this case study show that the presented methodology is useful in practice because (1) data sufficiency can be judged before conducting actual field experiments and (2) the identified WCP drastically reduces the computation time for constructing an objective‐oriented model.
Development of the 3‐D MHD model of the solar corona‐solar wind combining system
Authors: Nakamizo A. , Tanaka T. , Kubo Y. , Kamei S. , Shimazu H. , Shinagawa H.
Published: July 2009

In the framework of integrated numerical space weather prediction, we have developed a 3‐D MHD simulation model of the solar surface‐solar wind system. We report the construction method of the model and its first results. By implementing a grid system with angularly unstructured and increasing radial spacing, we realized a spherical grid that has no pole singularity and realized a fine grid size around the inner boundary and a wide‐range grid up to a size of 1 AU simultaneously. The magnetic field at the inner boundary is specified by the observational data. In order to obtain the supersonic solar wind speed, parameterized source functions are introduced into the momentum and energy equations. These source functions decay exponentially in altitude as widely used in previous studies. The absolute values of the source functions are controlled so as to reflect the topology of the coronal magnetic field. They are increased inside the magnetic flux tube with subradial expansion and reduced inside the magnetic flux tube with overradial expansion. This adjustment aims to reproduce the variation of the solar wind speed according to the coronal magnetic structure. The simulation simultaneously reproduces the plasma‐exit structure, the high‐ and low‐temperature regions, the open and closed magnetic field regions in the corona, the fast and slow solar wind, and the sector structure in interplanetary space. It is confirmed from the comparison with observations that the MHD model successfully reproduces many features of both the fine solar coronal structure and the global solar wind structure.
PCN magnetic index and average convection velocity in the polar cap inferred from SuperDARN radar measurements
Authors: Fiori R. A. D. , Koustov A. V. , Boteler D. , Makarevich R. A.
Published: July 2009

The relationship between the polar cap north (PCN) magnetic index and the average convection velocity of the plasma flow across the polar cap is investigated using data from both the Rankin Inlet (RKN) polar cap Super Dual Auroral Radar Network (SuperDARN) radar and the entire SuperDARN network. Correlation between the PCN index and the average velocity, determined from the median RKN line of sight (LOS) velocity, maximizes near magnetic noon and midnight when the radar field of view is roughly aligned with the noon‐midnight meridian. For observations between 1000 and 1100 MLT, a roughly linear increase of the average velocity was found for a PCN index between 0 and 2, but the rate of increase is ∼2 times faster than in previous publications in which the average velocity was estimated from DMSP ion drift measurements. Comparisons between the PCN index with the cross‐polar cap velocity estimated from (1) SuperDARN convection maps and (2) median RKN LOS velocities show similar trends. Both the average cross‐polar cap velocity (estimated by two methods) and the cross‐polar cap potential show a tendency for saturation at PCN > 2. No significant seasonal change in the nature of the relationships was found.
Understanding groundwater, surface water, and hyporheic zone biogeochemical processes in a Chalk catchment using fluorescence properties of dissolved and colloidal organic matter
Authors: Lapworth D. J. , Gooddy D. C. , Allen D. , Old G. H.
Published: July 2009

Understanding groundwater–surface water (GW–SW) interaction in Chalk catchments is complicated by the degree of geological heterogeneity. At this study site, in southern United Kingdom, alluvial deposits in the riparian zone can be considered as a patchwork of varying grades and types with an equally varied lateral connectivity. Some display good connection with the river system and others good connection with the groundwater system and, by definition, poorer connectivity with the surface water. By coupling tangential flow fractionation (TFF) with fluorescence analysis we were able to characterize the organic matter in the river and hyporheic zone. There is a significant proportion of particulate and colloidal fluorescent organic matter (FOM) within the river system and at depth within the gravels beneath the river channel. At depth in the hyporheic zone, the surface water inputs are dampened by mixing with deeper groundwater FOM. The shallow (0–0.5 m below river bed) hyporheic zone is highly dynamic as a result of changing surface water inputs from upstream processes. Labile C in the form of protein‐like FOM appears to be attenuated preferentially compared to fulvic‐like fluorescence in the hyporheic zone compared to the adjacent gravel and sand deposits. These preliminary findings have important implications for understanding nutrient and trace element mobility and attenuation within the groundwater, surface water, and hyporheic zone of permeable Chalk catchments. Fluorescence analysis of dissolved organic matter has been shown to be a useful environmental tracer that can be used in conjunction with other methods to understand GW–SW processes within a permeable Chalk catchment.
Water stress impacts on bacterial carbon monoxide oxidation on recent volcanic deposits
Authors: Weber Carolyn F , King Gary M
Published: July 2009

Water availability oscillates dramatically on young volcanic deposits, and may control the distribution and activity of microbes during early stages of biological succession. Carbon monoxide (CO)-oxidizing bacteria are among the pioneering colonists on volcanic deposits and are subjected to these water stresses. We report here the effects of water potential on CO-oxidizing bacteria in unvegetated (bare) and vegetated (canopy) sites on a 1959 volcanic deposit on Kilauea Volcano (Hawai'i). Time course measurements of water potential showed that average water potentials in the surface layer (0–1 cm) of canopy soil remained between −0.1 and 0 MPa, whereas dramatic diurnal oscillations (for example, between −60 and 0 MPa) occur in bare site surface cinders. During a moderate drying event in situ (−1.7 to 0 MPa), atmospheric CO consumption by intact bare site cores decreased 2.7-fold. For bare and canopy surface samples, maximum potential CO oxidation rates decreased 40 and 60%, respectively, when water potentials were lowered from 0 to −1.5 MPa in the laboratory. These observations indicated that CO oxidation is moderately sensitive to changes in water potential. Additional analyses showed that CO oxidation resumes within a few hours of rehydration, even after desiccation at −150 MPa for 63 days. Samples from both sites exposed to multiple cycles of drying and rewetting (−80 to 0 MPa), lost significant activity after the first cycle, but not after subsequent cycles. Similar responses of CO oxidation in both sites suggested that active CO-oxidizing communities in bare and canopy sites do not express differential adaptations to water stress.
Molecular characterization of the spatial diversity and novel lineages of mycoplankton in Hawaiian coastal waters
Authors: Gao Zheng , Johnson Zackary I , Wang Guangyi
Published: July 2009

Microbial community diversity and composition have critical biogeochemical roles in the functioning of marine ecosystems. Large populations of planktonic fungi exist in coastal ocean waters, yet their diversity and role in carbon and nutrient cycling remain largely unknown. Lack of information on critical functional microbial groups limits our understanding of their ecological roles in coastal oceans and hence our understanding of its functioning in the ocean's carbon and nutrient cycles. To address this gap, this study applied the molecular approach denaturing gradient gel electrophoresis (DGGE) coupled with clone library construction to investigate mycoplankton communities in Hawaiian coastal waters. Mycoplankton communities displayed distinct lateral and vertical variations in diversity and composition. Compared with the open ocean, surface (<100 m) near-shore waters had the greatest diversity and species richness of mycoplankton, whereas no differences were found among stations at depths below 150 m. Vertical diversity profiles in the coastal waters suggested that diversity and species richness were positively correlated to phytoplankton biomass in the coastal waters, but not in offshore waters. A total of 46 species were identified and belonging to two phyla Basidiomycota and Ascomycota, with the basidiomycetes as the dominant group (n=42). The majority (n=27) of the basidiomycetes are novel phylotypes showing less than 98% identity in the 18S rRNA gene with any sequence in GenBank. This study provides insight into mycoplankton ecology and is the first molecular analysis of planktonic fungi in the oceans.
The CB1 Antagonist Rimonabant Decreases Insulin Hypersecretion in Rat Pancreatic Islets
Authors: Getty‐Kaushik Lisa , Richard Ann‐Marie T. , Deeney Jude T. , Krawczyk Sarah , Shirihai Orian , Corkey Barbara E.
Published: July 2009

Type 2 diabetes and obesity are characterized by elevated nocturnal circulating free fatty acids, elevated basal insulin secretion, and blunted glucose‐stimulated insulin secretion (GSIS). The CB1 receptor antagonist, Rimonabant, has been shown to improve glucose tolerance and insulin sensitivity in vivo but its direct effect on islets has been unclear. Islets from lean littermates and obese Zucker (ZF) and Zucker Diabetic Fatty (ZDF) rats were incubated for 24 h in vitro and exposed to 11 mmol/l glucose and 0.3 mmol/l palmitate (GL) with or without Rimonabant. Insulin secretion was determined at basal (3 mmol/l) or stimulatory (15 mmol/l) glucose concentrations. As expected, basal secretion was significantly elevated in islets from obese or GL‐treated lean rats whereas the fold increase in GSIS was diminished. Rimonabant decreased basal hypersecretion in islets from obese rats and GL‐treated lean rats without decreasing the fold increase in GSIS. However, it decreased GSIS in islets from lean rats without affecting basal secretion. These findings indicate that Rimonabant has direct effects on islets to reduce insulin secretion when secretion is elevated above normal levels by diet or in obesity. In contrast, it appears to decrease stimulated secretion in islets from lean animals but not in obese or GL‐exposed islets.
Recent insights into the structure of Toll-like receptors and post-translational modifications of their associated signalling proteins
Authors: Carpenter Susan , O'Neill Luke A. J.
Published: July 2009

TLRs (Toll-like receptors) are essential modulators of the innate immune response through their ability to respond to a diverse range of conserved structures within microbes. Recent advances have been made in our understanding of the initiation of TLR signals as a result of the elucidation of crystal structures of TLRs interacting with their ligands. Most notably the structure of TLR1/2 with triacylated lipopeptide and TLR4 in a complex with LPS (lipopolysaccharide) and MD2 has been solved. These explain the basis for TLR dimerization which initiates signalling. Modifications of TLRs and their receptor proximal signalling proteins have also been uncovered. Phosphorylation of adaptor proteins and ubiquitination (both Lys48- and Lys63-linked) of TLRs, IRAKs (interleukin-1 receptor-associated kinase), Pellinos and TRAF6 (tumour-necrosis-factor-receptor-associated factor 6) have been described, which promote signalling and lead to signal termination. A detailed molecular account of the initiation and termination of TLR signalling is presented.
Fractal analysis of Xylella fastidiosa biofilm formation
Authors: Moreau A. L. D. , Lorite G. S. , Rodrigues C. M. , Souza A. A. , Cotta M. A.
Published: July 2009

We have investigated the growth process of Xylella fastidiosa biofilms inoculated on a glass. The size and the distance between biofilms were analyzed by optical images; a fractal analysis was carried out using scaling concepts and atomic force microscopy images. We observed that different biofilms show similar fractal characteristics, although morphological variations can be identified for different biofilm stages. Two types of structural patterns are suggested from the observed fractal dimensions Df. In the initial and final stages of biofilm formation, Df is 2.73±0.06 and 2.68±0.06, respectively, while in the maturation stage, Df=2.57±0.08. These values suggest that the biofilm growth can be understood as an Eden model in the former case, while diffusion-limited aggregation (DLA) seems to dominate the maturation stage. Changes in the correlation length parallel to the surface were also observed; these results were correlated with the biofilm matrix formation, which can hinder nutrient diffusion and thus create conditions to drive DLA growth.
Soft x-ray yield from NX2 plasma focus
Authors: Lee S. , Rawat R. S. , Lee P. , Saw S. H.
Published: July 2009

The Lee model code is used to compute neon soft x-ray yield Ysxr for the NX2 plasma focus as a function of pressure. Comparison with measured Ysxr shows reasonable agreement in the Ysxr versus pressure curve, the absolute maximum yield as well as the optimum pressure. This gives confidence that the code gives a good representation of the neon plasma focus in terms of gross properties including speeds and trajectories and soft x-ray yields, despite its lack of modeling localized regions of higher densities and temperatures. Computed current curves versus pressure are presented and discussed particularly in terms of the dynamic resistance of the axial phase. Computed gross properties of the plasma focus including peak discharge current Ipeak, pinch current Ipinch, minimum pinch radius rmin, plasma density at the middle duration of pinch npinch, and plasma temperature at middle duration of pinch Tpinch are presented and the trends in variation of these are discussed to explain the peaking of Ysxr at optimum pressure.
Electronic energy transfer on a vibronically coupled quantum aggregate
Authors: Roden Jan , Schulz Georg , Eisfeld Alexander , Briggs John
Published: July 2009

We examine the transfer of electronic excitation (an exciton) along a chain of electronically coupled monomers possessing internal vibronic structure and which also interact with degrees of freedom of the surrounding environment. Using a combination of analytical and numerical methods, we calculate the time evolution operator or time-dependent Green’s function of the system and thereby isolate the physical parameters influencing the electronic excitation transport. Quite generally, we show that coupling to vibrations slows down and inhibits migration of electronic excitation due to dephasing effects on the coherent transfer present without vibrations. In particular, coupling to a continuous spectrum of environment states leads to a complete halting of transfer, i.e., a trapping of the exciton.
Modeling polymer-induced interactions between two grafted surfaces: Comparison between interfacial statistical associating fluid theory and self-consistent field theory
Authors: Jain Shekhar , Ginzburg Valeriy V. , Jog Prasanna , Weinhold Jeffrey , Srivastava Rakesh , Chapman Walter G.
Published: July 2009

The interaction between two polymer grafted surfaces is important in many applications, such as nanocomposites, colloid stabilization, and polymer alloys. In our previous work [Jain et al., J. Chem. Phys. 128, 154910 (2008)], we showed that interfacial statistical associating fluid density theory (iSAFT) successfully calculates the structure of grafted polymer chains in the absence/presence of a free polymer. In the current work, we have applied this density functional theory to calculate the force of interaction between two such grafted monolayers in implicit good solvent conditions. In particular, we have considered the case where the segment sizes of the free (σf) and grafted (σg) polymers are different. The interactions between the two monolayers in the absence of the free polymer are always repulsive. However, in the presence of the free polymer, the force either can be purely repulsive or can have an attractive minimum depending upon the relative chain lengths of the free (Nf) and grafted polymers (Ng). The attractive minimum is observed only when the ratio α=Nf/Ng is greater than a critical value. We find that these critical values of α satisfy the following scaling relation: ρgNgβ3∝α−λ, where β=σf/σg and λ is the scaling exponent. For β=1 or the same segment sizes of the free and grafted polymers, this scaling relation is in agreement with those from previous theoretical studies using self-consistent field theory (SCFT). Detailed comparisons between iSAFT and SCFT are made for the structures of the monolayers and their forces of interaction. These comparisons lead to interesting implications for the modeling of nanocomposite thermodynamics.
Polyethylcyanoacrylate nanoparticle transport through the stratum corneum
Authors: Díaz-Torres Roberto , Jiménez Sandoval Sergio J. , Ibañez-Orozco Oscar , Rodríguez-Romo Suemi
Published: July 2009

The traceability of polyethylcyanoacrylate nanoparticles transported through human skin is studied in this paper. Photoluminescence is used to find the precise diffusion path of polyethylcyanoacrylate nanoparticles through the skin stratum corneum (SC). Reproducible data were obtained, and the nanoparticles’ distribution in each layer of the SC is presented. We contribute to the basic knowledge of these phenomena as a stationary stochastic process using a one-dimensional linear chain model with the left end open and the right end closed. Possible applications are in the field of pharmaceutical technology, especially concerning drug transport through the skin by nanoparticle carriers.
On the additivity of current density in polycyclic aromatic hydrocarbons
Authors: Monaco Guglielmo , Zanasi Riccardo
Published: July 2009

Calculations of the π current density for polycyclic aromatic hydrocarbons placed in a uniform magnetic field reveal in some cases a substantial localization on subunits. This localization can be anticipated either for molecules with a factorizable Kekulé count K, in light of some theoretical models of ring currents, or for system with proper symmetry, in light of magnetic group theory. We have addressed the problem of whether the localization is compatible with a description of the current density field as a sum of current density fields, studying the sum of two purely rotational fields. When this general model is specialized with the parameters taken from benzene ring current, it turns out that two corotating purely rotational fields separated by a distance comparable to a chemical bond must be separated by a saddle point. We have looked for the occurrence of this criterion in K-factorizable molecules, chosen according to a novel corollary to Kasteleyn’s theorem, in coronenes, which have patterns localized by symmetry and in some further systems reported in literature. For those systems already described to have an additive current density pattern, the separating bonds do host saddle points, which are thus effective signatures of additivity.
Structural and electrical characterization of SiO2/MgO(001) barriers on Si for a magnetic transistor
Authors: Kohn A. , Kovács A. , Uhrmann T. , Dimopoulos T. , Brückl H.
Published: July 2009

We report a structural and electrical study of sputter-deposited SiO2/MgO barriers for developing magnetic Si-based transistors. We propose that SiO2/MgO tunneling barriers may utilize spin-filtering by achieving crystalline MgO (001) while reducing spin-scattering due to the Si/SiO2 interface. We find that MgO (<3 nm thick) crystallizes with (001) preferred orientation on thermally oxidized Si(<2 nm). Typical processing temperatures do not cause significant intermixing with SiO2 or ferromagnetic electrode. Conversely, MgO on Si is amorphous up to 2 nm thick. Capacitance-voltage characteristics of MgO capacitors are influenced significantly by the density of interface-states, as high as 5×1013 cm−2 eV−1 while Si/SiO2/MgO structures are electrically beneficial by reducing to 6×1012 cm−2 eV−1.
Anomalous magnetizations in melt spinning Ni–Mn–Ga
Authors: Wang Jingmin , Jiang Chengbao , Techapiesancharoenkij Ratchatee , Bono David , Allen Samuel M. , O’Handley Robert C.
Published: July 2009

The structural and magnetic characteristics were studied for martensitic and austenitic Ni–Mn–Ga melt-spun ribbons of as quenched and as annealed at different temperatures. No essential structure change was found before and after annealing, but there are some anomalies in the magnetization process. In the austenite state the M(T) curves measured in 100 Oe field exhibit a Hopkinson peak at TC for the ribbons of as quenched and annealed at 573 and 773 K, but the curves monotonically decays to zero with the increasing temperature to TC after annealing at 1073 K. In the martensite phase of both as quenched and 573 K annealed ribbons an abrupt increase in the slope of the M(H) curve was observed; it appears to be due to the onset of magnetic-field-induced twin boundary motion. The abrupt slope change disappeared in the ribbons annealed at temperatures higher than 773 K. The ribbon processing history and particularly the quenched-in internal stress were modeled to probe the possible mechanisms for the anomalous magnetization behaviors, combining the grain-grain strain stored in the polycrystalline. The annealing temperatures were clarified into three groups according to their effects on the magnetization behaviors of the austenite and martensite.
An infrared imaging method for high-throughput combinatorial investigation of hydrogenation-dehydrogenation and new phase formation of thin films
Authors: Oguchi H. , Hattrick-Simpers J. , Takeuchi I. , Heilweil E. J. , Bendersky L. A.
Published: July 2009

We have developed an infrared imaging setup enabling in situ infrared images to be acquired, and expanded on capabilities of an infrared imaging as a high-throughput screening technique, determination of a critical thickness of a Pd capping layer which significantly blocks infrared emission from below, enhancement of sensitivity to hydrogenation and dehydrogenation by normalizing raw infrared intensity of a Mg thin film to an inert reference, rapid and systematic screening of hydrogenation and dehydrogenation properties of a Mg–Ni composition spread covered by a thickness gradient Pd capping layer, and detection of formation of a Mg2Si phase in a Mg thin film on a thermally oxidized Si substrate during annealing.
Electron paramagnetic resonance and Mössbauer study of antiferromagnetic K3Cu3Fe2F15
Authors: Blinc R. , Tavčar G. , Žemva B. , Goreshnik E. , Hanžel D. , Cevc P. , Potočnik A. , Laguta V. , Trontelj Z. , Jagličič Z. , Scott J. F.
Published: July 2009

The electron paramagnetic resonance (EPR) spectra of K3Cu3Fe2F15 consist above 85 K of a superposition of two Lorentzians with different intensities, T-dependences, linewidths, and g-factors. The broad line shows an antiferromagnetic (AFM) behavior and the narrow one shows a paramagneticlike behavior. The Mössbauer spectra consist at room temperature of two quadrupolar doublets and below 77 K of two magnetic sextets and one quadrupolar doublet. Below 85 K the broad line EPR disappears and the intensity of the narrow line increases nearly exponentially with decreasing temperature. The broad EPR line originates from regions with local AFM order, whereas the narrow line comes from regions without AFM order, e.g., grain boundaries.
A “cellular neuronal” approach to optimization problems
Authors: Duane Gregory S.
Published: July 2009

The Hopfield–Tank [J. J. Hopfield and D. W. Tank, Biol. Cybern. 52, 141 (1985)] recurrent neural network architecture for the traveling salesman problem is generalized to a fully interconnected “cellular” neural network of regular oscillators. Tours are defined by synchronization patterns, allowing the simultaneous representation of all cyclic permutations of a given tour. The network converges to local optima some of which correspond to shortest-distance tours, as can be shown analytically in a stationary phase approximation. Simulated annealing is required for global optimization, but the stochastic element might be replaced by chaotic intermittency in a further generalization of the architecture to a network of chaotic oscillators.
On the Hooge relation in semiconductors and metals
Authors: Dmitriev A. P. , Levinshtein M. E. , Rumyantsev S. L.
Published: July 2009

The expressions describing the low frequency noise caused by defects in semiconductors and metals have been obtained in the framework of a general unified approach for both fluctuations in the number of carriers and their mobility. When fluctuations in the number of carriers are responsible for noise, the spectral noise density is inversely proportional to the carrier concentration squared and to the volume of the sample. The spectral density of the noise caused by mobility fluctuations is inversely proportional to the sample volume, and does not depend either on carrier concentration or on the total number of carriers. In the case when both mechanisms contribute to noise and they are correlated, the dependence of the noise on the number of carriers depends on the relative contribution of these two noise mechanisms. The expressions obtained can be associated with corresponding cases of the 1/f noise. The physical basis and limitations of the Hooge formula are discussed.
The electronegativity equalization method and the split charge equilibration applied to organic systems: Parametrization, validation, and comparison
Authors: Verstraelen Toon , Van Speybroeck Veronique , Waroquier Michel
Published: July 2009

An extensive benchmark of the electronegativity equalization method (EEM) and the split charge equilibration (SQE) model on a very diverse set of organic molecules is presented. These models efficiently compute atomic partial charges and are used in the development of polarizable force fields. The predicted partial charges that depend on empirical parameters are calibrated to reproduce results from quantum mechanical calculations. Recently, SQE is presented as an extension of the EEM to obtain the correct size dependence of the molecular polarizability. In this work, 12 parametrization protocols are applied to each model and the optimal parameters are benchmarked systematically. The training data for the empirical parameters comprise of MP2/Aug-CC-pVDZ calculations on 500 organic molecules containing the elements H, C, N, O, F, S, Cl, and Br. These molecules have been selected by an ingenious and autonomous protocol from an initial set of almost 500 000 small organic molecules. It is clear that the SQE model outperforms the EEM in all benchmark assessments. When using Hirshfeld-I charges for the calibration, the SQE model optimally reproduces the molecular electrostatic potential from the ab initio calculations. Applications on chain molecules, i.e., alkanes, alkenes, and alpha alanine helices, confirm that the EEM gives rise to a divergent behavior for the polarizability, while the SQE model shows the correct trends. We conclude that the SQE model is an essential component of a polarizable force field, showing several advantages over the original EEM.
Robust coupling of superconducting order parameter in a mesoscale NbN–Fe–NbN epitaxial structure
Authors: Bose S. K. , Budhani R. C.
Published: July 2009

We report an unconventional and promising route to self-assemble distributed superconductor-ferromagnet-superconductor (S-F-S) Josephson junctions on single crystal [100] MgO. These structures consist of [110] epitaxial nanoplaquettes of Fe covered with superconducting NbN films of varying thickness. The S-F-S structures are characterized by a strong magnetoresistance (MR) anisotropy for the in-plane and out-of-plane magnetic fields. The stronger in-plane MR suggests decoherence of S-F-S junctions whose critical current follows a (1−T/Tc) and (1−T/Tc)1/2 dependence for T≈Tc and T⪡Tc, respectively, in accordance with the theory of supercurrent transport in such junctions.
Bayesian comparison of Markov models of molecular dynamics with detailed balance constraint
Authors: Bacallado Sergio , Chodera John D. , Pande Vijay
Published: July 2009

Discrete-space Markov models are a convenient way of describing the kinetics of biomolecules. The most common strategies used to validate these models employ statistics from simulation data, such as the eigenvalue spectrum of the inferred rate matrix, which are often associated with large uncertainties. Here, we propose a Bayesian approach, which makes it possible to differentiate between models at a fixed lag time making use of short trajectories. The hierarchical definition of the models allows one to compare instances with any number of states. We apply a conjugate prior for reversible Markov chains, which was recently introduced in the statistics literature. The method is tested in two different systems, a Monte Carlo dynamics simulation of a two-dimensional model system and molecular dynamics simulations of the terminally blocked alanine dipeptide.
Fabrication and characterization of Er silicates on SiO2/Si substrates
Authors: Wang X. J. , Nakajima T. , Isshiki H. , Kimura T.
Published: July 2009

Er silicates have been fabricated on SiO2/Si(100) substrates by the sol-gel method. In contrast to Si(100) substrates, on which the Er2SiO5 phase in general crystallizes, the α-Er2Si2O7 with the photoluminescence (PL) main peak at 1531 nm formed at 1200 °C. The integrated PL intensity of the α-Er2Si2O7 phase was about five to ten times stronger than that of the Er2SiO5 phase, and the α-Er2Si2O7 phase showed a relatively long decay time (100–300 μs) in contrast to several tens of microseconds of the Er2SiO5 phase. Excess O from SiO2 layer may lead to the formation of the α-Er2Si2O7 phase.
Mineralogical constraints on the paleoenvironments of the Ediacaran Doushantuo Formation
Authors: Bristow Thomas F. , Kennedy Martin J. , Derkowski Arkadiusz , Droser Mary L. , Jiang Ganqing , Creaser Robert A.
Published: July 2009

Assemblages of clay minerals are routinely used as proxies for paleoclimatic change and paleoenvironmental conditions in Phanerozoic rocks. However, this tool is rarely applied in older sedimentary units. In this paper, the clay mineralogy of the Doushantuo Formation in South China is documented, providing constraints on depositional conditions of the Ediacaran Yangtze platform that host the earliest animal fossils in the geological record. In multiple sections from the Yangtze Gorges area, trioctahedral smectite (saponite) and its diagenetic products (mixed-layer chlorite/smectite, corrensite, and chlorite) are the dominant clays through the lower 80 m of the formation and constitute up to 30 wt% of the bulk rock. Saponite is interpreted as an in situ early diagenetic phase that formed in alkaline conditions (pH ≥ 9). The absence of saponite in stratigraphically equivalent basin sections, 200–400 km to the south, indicates that alkaline conditions were localized in a nonmarine basin near the Yangtze Gorges region. This interpretation is consistent with crustal abundances of redox-sensitive trace elements in saponitic mudstones deposited under anoxic conditions, as well as a 10‰ difference in the carbon isotope record between Yangtze Gorges and basin sections. Our findings suggest that nonmarine environments may have been hospitable for the fauna preserved in the Yangtze Gorges, which includes the oldest examples of animal embryo fossils and acanthomorphic acritarchs.
Circulating CD21lowB cells in common variable immunodeficiency resemble tissue homing, innate-like B cells
Authors: Rakhmanov Mirzokhid , Keller Baerbel , Gutenberger Sylvia , Foerster Christian , Hoenig Manfred , Driessen Gertjan , van der Burg Mirjam , van Dongen Jacques J. , Wiech Elisabeth , Visentini Marcella , Quinti Isabella , Prasse Antje , Voelxen Nadine , Salzer Ulrich , Goldacker Sigune , Fisch Paul , Eibel Hermann , Schwarz Klaus , Peter Hans-Hartmut , Warnatz Klaus
Published: July 2009

The homeostasis of circulating B cell subsets in the peripheral blood of healthy adults is well regulated, but in disease it can be severely disturbed. Thus, a subgroup of patients with common variable immunodeficiency (CVID) presents with an extraordinary expansion of an unusual B cell population characterized by the low expression of CD21. CD21lowB cells are polyclonal, unmutated IgM+IgD+B cells but carry a highly distinct gene expression profile which differs from conventional naïve B cells. Interestingly, while clearly not representing a memory population, they do share several features with the recently defined memory-like tissue, Fc receptor-like 4 positive B cell population in the tonsils of healthy donors. CD21lowB cells show signs of previous activation and proliferation in vivo, while exhibiting defective calcium signaling and poor proliferation in response to B cell receptor stimulation. CD21lowB cells express decreased amounts of homeostatic but increased levels of inflammatory chemokine receptors. This might explain their preferential homing to peripheral tissues like the bronchoalveolar space of CVID or the synovium of rheumatoid arthritis patients. Therefore, as a result of the close resemblance to the gene expression profile, phenotype, function and preferential tissue homing of murine B1 B cells, we suggest that CD21lowB cells represent a human innate-like B cell population.
Anomalous yet Brownian
Authors: Wang Bo , Anthony Stephen M. , Bae Sung Chul , Granick Steve
Published: July 2009

We describe experiments using single-particle tracking in which mean-square displacement is simply proportional to time (Fickian), yet the distribution of displacement probability is not Gaussian as should be expected of a classical random walk but, instead, is decidedly exponential for large displacements, the decay length of the exponential being proportional to the square root of time. The first example is when colloidal beads diffuse along linear phospholipid bilayer tubes whose radius is the same as that of the beads. The second is when beads diffuse through entangled F-actin networks, bead radius being less than one-fifth of the actin network mesh size. We explore the relevance to dynamic heterogeneity in trajectory space, which has been extensively discussed regarding glassy systems. Data for the second system might suggest activated diffusion between pores in the entangled F-actin networks, in the same spirit as activated diffusion and exponential tails observed in glassy systems. But the first system shows exceptionally rapid diffusion, nearly as rapid as for identical colloids in free suspension, yet still displaying an exponential probability distribution as in the second system. Thus, although the exponential tail is reminiscent of glassy systems, in fact, these dynamics are exceptionally rapid. We also compare with particle trajectories that are at first subdiffusive but Fickian at the longest measurement times, finding that displacement probability distributions fall onto the same master curve in both regimes. The need is emphasized for experiments, theory, and computer simulation to allow definitive interpretation of this simple and clean exponential probability distribution.
Mouse Kif7/Costal2 is a cilia-associated protein that regulates Sonic hedgehog signaling
Authors: Liem Karel F. , He Mu , Ocbina Polloneal Jymmiel R. , Anderson Kathryn V.
Published: July 2009

Mammalian Sonic hedgehog (Shh) signaling is essential for embryonic development and stem cell maintenance and has critical roles in tumorigenesis. Although core components of the Shh pathway are conserved in evolution, important aspects of mammalian Shh signaling are not shared with the
Drosophila
pathway. Perhaps the most dramatic difference between the
Drosophila
and mammalian pathways is that Shh signaling in the mouse requires a microtubule-based organelle, the primary cilium. Proteins that are required for the response to Shh are enriched in the cilium, but it is not clear why the cilium provides an appropriate venue for signal transduction. Here, we demonstrate that Kif7, a mammalian homologue of
Drosophila
Costal2 (Cos2), is a cilia-associated protein that regulates signaling from the membrane protein Smoothened (Smo) to Gli transcription factors. By using a
Kif7
mutant allele identified in a reporter-based genetic screen, we show that, similar to
Drosophila
and zebrafish Cos2, mouse Kif7 acts downstream of Smo and upstream of Gli2 and has both negative and positive roles in Shh signal transduction. Mouse Kif7 activity depends on the presence of cilia and Kif7-eGFP localizes to base of the primary cilium in the absence of Shh. Activation of the Shh pathway promotes trafficking of Kif7-eGFP from the base to the tip of the cilium, and localization to the tip of the cilium is disrupted in a motor domain mutant. We conclude that Kif7 is a core regulator of Shh signaling that may also act as a ciliary motor.
IL-1 family members and STAT activators induce cytokine production by Th2, Th17, and Th1 cells
Authors: Guo Liying , Wei Gang , Zhu Jinfang , Liao Wei , Leonard Warren J. , Zhao Keji , Paul William
Published: July 2009

Expression of T1ST2, the IL-33R, by Th2 cells requires GATA3. Resting Th2 cells express little GATA3, which is increased by IL-33 and a STAT5 activator, in turn increasing T1ST2 from its low-level expression on resting Th2 cells. Th2 cells that have upregulated T1ST2 produce IL-13, but not IL-4, in response to IL-33 plus a STAT5 activator in an antigen-independent, NF-κB-dependent, cyclosporin A (CsA)-resistant manner. Similarly, Th17 cells produce IL-17A in response to IL-1β and a STAT3 activator and Th1 cells produce IFNγ in response to IL-18 and a STAT4 inducer. Thus, each effector Th cell produces cytokines without antigenic stimulation in response to an IL-1 family member and a specific STAT activator, implying an innate mechanism through which memory CD4 T cells are recruited by an induced cytokine environment.
Methicillin-Resistant Staphylococcus aureus Colonization of House Officers
Authors: Barbosa Anna A. , Chapin Kim , Mermel Leonard A.
Published: July 2009

We performed a prospective prevalence survey of methicillin-resistant Staphylococcus aureus (MRSA) carriage in the nares of 50 medical and 50 surgical house officers. None of the 50 internal medicine house officers and 5 of the 50 general surgery house officers had MRSA nares colonization (P = .03). None of the MRSA isolates recovered from the surgical house officers were identical.
Risk Factors for Spinal Surgical Site Infection, Houston, Texas
Authors: Boston Kelley M. , Baraniuk Sarah , O'Heron Shana , Murray Kristy O.
Published: July 2009

Objective.

Because of an increase in the rate of surgical site infections (SSIs) following spinal procedures at the study hospital, we conducted a study to determine risk factors associated with the development of a SSI.

Design.

Case-control study.

Setting.

A community hospital in Houston, Texas, with more than 500 beds.

Patients.

Fifty-five case patients who developed SSI after spinal surgery and 179 control patients who did not develop SSI after spinal surgery.

Methods.

We examined patient- and hospital-associated risk factors for SSI by using existing data on patients who underwent spinal operations at the study hospital between December 2003 and August 2005. Multivariable analysis was conducted using logistic regression to determine significant risk factors associated with SSI.

Results.

The presence of comorbidities (odds ratio [OR], 3.15 [95% confidence interval (CI), 1.20-8.26]) and surgical duration greater than the population median of 100 minutes (OR, 2.48 [95% CI, 1.12-5.49]) were identified as independent risk factors for SSI. The use of only povidone-iodine for preoperative skin antisepsis was found to be protective (OR, 0.16 [95% CI, 0.06-0.45]). Specific operating room, hospital staff involved in the procedures, workers' compensation status, method of hair removal, smoking status, or incontinence were not statistically significant.

Conclusions.

The presence of comorbidities and increased surgical duration are risks for postoperative infection. The use of only povidone-iodine was found to decrease the risk of infection.