bluuebunny/crossref_metadata_2025 huggingface dataset:
Aquifer Transmissivity from Surface Geo-electrical Data: A Case Study of Owerri and Environs, Southeastern Nigeria
Authors: Ekwe A. C. , Opara A. I.
Published: July 2012

The combination of layer resistivity and thickness in the so called Da-zarrouk parameters S (longitudinal conductance) and R (transverse resistance) have proved useful in the evaluation of the transmissivities of the aquifers around Owerri and environs. The area is underlain by the unconsolidated to semi-consolidated coastal Benin Formation. The surface direct current electrical resistivity method was used in the study. Seven Vertical Electrical Soundings (VES) data by the Schlumberger array was acquired in the area. A maximum current electrode spacing (AB) of 1000 m was used for data acquisition. Four of the soundings were carried out near existing boreholes. Computer modelled interpretative methods was utilized in processing the data. Results show that the depth to the water level is shallow around Ife and Egbu areas with a mean depth of 30 m. Semi-deep aquifers were encountered around Okpalla and AVU areas with a mean depth of 90 m while very deep aquifers were sensed around Owerri and Obinze areas with a mean depth of 125 m. Aquifer thicknesses in the study area range from 8 m at Ife and 117 m at Owerri. The diagnostic Kσ = constant value have proved so useful in calculating transmisivities and hydraulic conductivities of all the sounding locations including areas where no boreholes exist. Hydraulic conductivity varies between 6.19m/day at Ife and 24.7 m/day at Obinze. Transmissivity values also very between 51.39 m2/day at Ife and 1379.56 m2/day at Owerri. It is hoped that the results would help in long term planning of groundwater exploitation schemes within the study area.
Lane–Emden problems: Asymptotic behavior of low energy nodal solutions
Authors: Pacella Filomena , Grossi Massimo , Grumiau Christopher
Published: July 2012

We study the nodal solutions of the Lane–Emden–Dirichlet problem

\begin{cases}
−\mathrm{\Delta }u = |u|^{p−1}u, & \text{in }\Omega , \\ u = 0, & \text{on }\partial \Omega ,
\end{cases}

where

Ω

is a smooth bounded domain in

\mathbb{R}^{2}

and

p > 1

. We consider solutions

u_{p}

satisfying

\tag{$\ast$}
p\int \limits_{\Omega }|\mathrm{∇}u_{p}|^{2}\rightarrow 16\pi e\:\text{as }p\rightarrow + \infty

and we are interested in the shape and the asymptotic behavior as

p\rightarrow + \infty

.

First we prove that (

\ast

) holds for least energy nodal solutions. Then we obtain some estimates and the asymptotic profile of this kind of solutions. Finally, in some cases, we prove that

pu_{p}

can be characterized as the difference of two Greenʼs functions and the nodal line intersects the boundary of

Ω

, for large

p

.
Systems biology of cellular rhythms
Authors: Goldbeter A. , Gérard C. , Gonze D. , Leloup J.-C. , Dupont G.
Published: July 2012

► Detailed survey of experimental and modeling approaches to cellular rhythms. ► Cellular rhythms in development : from cAMP oscillations to the segmentation clock. ► Frequency‐encoded cellular rhythms: GnRH, Calcium, and cAMP pulses. ► The Cdk network driving the cell cycle behaves as a self‐sustained oscillator. ► Coupled cellular rhythms: the cell cycle, Ca++ spiking, and the circadian clock.
MRPS27 is a pentatricopeptide repeat domain protein required for the translation of mitochondrially encoded proteins
Authors: Davies Stefan M.K. , Lopez Sanchez Maria I.G. , Narsai Reena , Shearwood Anne-Marie J. , Razif Muhammad F.M. , Small Ian D. , Whelan James , Rackham Oliver , Filipovska Aleksandra
Published: July 2012

MRPS27 and MRPS15 colocalize by cosedimentation through density gradient (View Interaction)
Antibody–antigen pair probed by combinatorial approach and rational design: Bringing together structural insights, directed evolution, and novel functionality
Authors: Belogurov Alexey , Smirnov Ivan , Ponomarenko Natalya , Gabibov Alexander
Published: July 2012

The unique hypervariability of the immunoglobulin (Ig) superfamily provides a means to create both binding and catalytic antibodies with almost any desired specificity and activity. The diversity of antigens and concept of adaptive response suggest that it is possible to find an antigen pair to any raised Ig. In the current review we discuss combinatorial approaches, which makes it possible to obtain an antibody with predefined properties, followed by 3D structure‐based rational design to enhance or dramatically change its characteristics. A similar strategy, but applied to the second partner of the antibody–antigen pair, may result in selection of complementary substrates to the chosen Ig. Finally, 2D screening may be performed solving the “Chicken and Egg” problem when neither antibody nor antigen is known.
The strength of the miR398‐Csd2‐CCS1 regulon is subject to natural variation in Arabidopsis thaliana
Authors: Juszczak Ilona , Baier Margarete
Published: July 2012

miR398 links expression of the three major chloroplast copper proteins, plastocyanin, CCS1 and Csd2, to copper availability. miR398 abundance was stronger plastocyanin‐controlled in accessions from cold and continental habitats (Kas‐1, Ms‐0, WS) than in Cvi‐0 and Col‐0. Target gene regulation was broken for Csd2 in Cvi‐0 upon cold‐treatment. Comparison of miR398 levels, target gene regulation as well as Ago1 and miR168 expression demonstrated that the miR398 regulon can be overwritten by accession specific transcriptional regulation in Cvi‐0. It is concluded that the escape from the miRNA control of copper homeostasis is linked to adaptation of Cvi‐0 to its harsh natural habitat.
Catalytic promiscuity of a bacterial α‐N‐methyltransferase
Authors: Zhang Qi , van der Donk Wilfred A.
Published: July 2012

The posttranslational methylation of N‐terminal α‐amino groups (α‐N‐methylation) is a ubiquitous reaction found in all domains of life. Although this modification usually occurs on protein substrates, recent studies have shown that it also takes place on ribosomally synthesized natural products. Here we report an investigation of the bacterial α‐N‐methyltransferase CypM involved in the biosynthesis of the peptide antibiotic cypemycin. We demonstrate that CypM has low substrate selectivity and methylates a variety of oligopeptides, cyclic peptides such as nisin and haloduracin, and the ε‐amino group of lysine. Hence it may have potential for enzyme engineering and combinatorial biosynthesis. Bayesian phylogenetic inference of bacterial α‐N‐methyltransferases suggests that they have not evolved as a specific group based on the chemical transformations they catalyze, but that they have been acquired from various other methyltransferase classes during evolution.
Arabidopsis Zinc Ribbon 3 is the ortholog of yeast mitochondrial HSP70 escort protein HEP1 and belongs to an ancient protein family in mitochondria and plastids
Authors: Kluth Jantjeline , Schmidt Annika , März Manuela , Krupinska Karin , Lorbiecke René
Published: July 2012

ZR3 physically interacts with mtHSC70‐1 by pull down (View interaction)
The use of a rotational bladder flap for the repair of recurrent mixed trigonal–supratrigonal vesicovaginal fistulas
Authors: Sharifiaghdas Farzaneh , Taheri Maryam
Published: July 2012

Objective

To describe an approach for managing 10 patients with complex, mixed trigonal–supratrigonal vesiõcovaginal fistulas (VVFs) using the rotational bladder flap technique.

Methods

The 10 patients were undergoing their second to fourth repair of a mixed trigonal–supratrigonal VVF. The fistula was approached transabdominally, the bladder was opened along the sagittal plane and a bladder flap was rotated downward and medially to fill the fistula defect. First, the vaginal defect was repaired as usual; then, an omental flap was interposed and fixed between the vagina and bladder; finally, the fistula and posterior wall of the bladder were meticulously sutured in 1 layer.

Results

Fistula closure was unsuccessful in 1 patient, in whom the corrugated drain had entered the bladder via the suture line. The fistulas were repaired successfully in the 9 remaining patients, with no recurrence or surgical reintervention for any reason for the follow‐up duration.

Conclusion

The rotational bladder flap technique is safe and effective for the repair of complex, mixed trigonal–supratrigonal VVFs which always require tension‐free approximation.
Gordon Unbound: The Heresthetic of Central Bank Independence in Britain
Authors: Dellepiane-Avellaneda Sebastian
Published: July 2012

This article combines theory and narrative to shed new light on the politics surrounding the making of central bank independence in contemporary Britain. Its central argument is that Gordon Brown's rewriting of the British monetary constitution in May 1997 constituted political manipulation in a Rikerian sense. The government removed a contentious issue from party politics in order to signal competence and enforce internal discipline. Building on Elster's constraint theory, the paper argues that Brown adopted a pre-commitment strategy aimed at binding others. The heresthetic move had dual consequences, both constraining and enabling. The institutionalization of discipline enabled New Labour to achieve economic and political goals. By revisiting the political rationality of precommitment, this article questions the dominant credibility story underlying the choice of economic institutions.
Global variation in the prevalence and incidence of major depressive disorder: a systematic review of the epidemiological literature
Authors: Ferrari A. J. , Somerville A. J. , Baxter A. J. , Norman R. , Patten S. B. , Vos T. , Whiteford H. A.
Published: July 2012

Background

Summarizing the epidemiology of major depressive disorder (MDD) at a global level is complicated by significant heterogeneity in the data. The aim of this study is to present a global summary of the prevalence and incidence of MDD, accounting for sources of bias, and dealing with heterogeneity. Findings are informing MDD burden quantification in the Global Burden of Disease (GBD) 2010 Study.

Method

A systematic review of prevalence and incidence of MDD was undertaken. Electronic databases Medline, PsycINFO and EMBASE were searched. Community-representative studies adhering to suitable diagnostic nomenclature were included. A meta-regression was conducted to explore sources of heterogeneity in prevalence and guide the stratification of data in a meta-analysis.

Results

The literature search identified 116 prevalence and four incidence studies. Prevalence period, sex, year of study, depression subtype, survey instrument, age and region were significant determinants of prevalence, explaining 57.7% of the variability between studies. The global point prevalence of MDD, adjusting for methodological differences, was 4.7% (4.4–5.0%). The pooled annual incidence was 3.0% (2.4–3.8%), clearly at odds with the pooled prevalence estimates and the previously reported average duration of 30 weeks for an episode of MDD.

Conclusions

Our findings provide a comprehensive and up-to-date profile of the prevalence of MDD globally. Region and study methodology influenced the prevalence of MDD. This needs to be considered in the GBD 2010 study and in investigations into the ecological determinants of MDD. Good-quality estimates from low-/middle-income countries were sparse. More accurate data on incidence are also required.
Topological pressure and the variational principle for actions of sofic groups
Authors: CHUNG NHAN-PHU
Published: July 2012

We introduce topological pressure for continuous actions of countable sofic groups on compact metrizable spaces. This generalizes the classical topological pressure for continuous actions of countable amenable groups on such spaces. We also establish the variational principle for topological pressure in this sofic context.
The role of within-language vocabulary size in children's semantic development: evidence from bilingual children
Authors: KEITH MARGAUX , NICOLADIS ELENA
Published: July 2012

This study tested whether bilingual children show a lag in semantic development (the schematic–categorical shift) relative to monolingual children due to smaller vocabularies within a language. Twenty French–English bilingual and twenty English monolingual children (seven to ten years old) participated in a picture-naming task in English. Their errors were coded for schematic or categorical relations. The bilingual children made more schematic errors than monolinguals, a difference that was accounted for statistically by vocabulary score differences. This result suggests that within-language vocabulary size is one important factor in semantic development and may explain why bilingual children sometimes show a lag relative to monolingual children in one of their languages, perhaps the language in which they have received less formal instruction.
Associations among Physician Advice, Physical Activity, and Socio-demographic Groups in Older Spanish Adults
Authors: Rodríguez María Martín , Castillo Jesús Martínez del , Sánchez José Antonio Serrano , Jiménez-Beatty Navarro José Emilio , Santacruz José Antonio , Herráiz Antonio Rivero
Published: July 2012

Cette étude a examiné la relation entre l’avis médicale pour s’engager dans ld’activité physique avec, le type de demande d’activité physique et les variables démographiques. Une étude transversale a été élaborécréé. Un questionnaire avec des items sur l’avis médicale, le niveau de demande pour l’activité physique, et les variables démographiques a été complété par une échantillon national de personnes âgées en Espagne (N = 933, M = 74,1, range de 65 à 93), sélectionnées de manière aléatoire à plusieurs étapes. Les personnes âgées actifs actives physiquement ont plus souvent reçu des avis médicale médicaux à la pratiquepour s’engager dans ld’activité physique que les personnes non activefs. Il existe une relation significative entre l’avis médicale et le type de demande (p <.01) et l’âge (p <.05). Cependant, aucune relation n’a été trouvée déterminée entre l’avis médicale d’activité physique et le sexe, la classe sociale, ou le revenu. Les médécins peuvent effectivement favoriserencourager l’activité physique chez les adultes âgés sédentaires par des conseils d’activité physiqueavec un résultat efficace. Donc, les autorités sanitaires devraient promouvoir encourager aux médécins de conseiller à leurs patients plus âgés de s’engager dans l’activité physiqueles conseils médicaux de l’activité physique à leurs patients âgés.
Long-Term Care Residents with Cancer and their Health Care Providers Reflect on Hope
Authors: Gibson Maggie , Gorman Eunice
Published: July 2012

Cette étude a examiné l’espoir parmi les résidents avec le cancer en soins de longue durée et a évalué les points de vue des résidents et aussi des prestataires de soins de santé (PSS). Les données cliniques ont établi que la prévalence d’un diagnostic de cancer dans l’établissement d’étude (15%) était semblable à d’autres estimations dans la littérature. On a fait passer une entrevue parmi huit PSS experimentés. Dix résidents avec un diagnostic de cancer ont été interrogés, et ils ont complété l’index d’espoir Herth (IEH). Les dimensions de l’espoir et les facteurs contextuels qui forment l’espoir sont manifestés comme des thèmes, et pour less PSS et pour les résidents, mais reflétaient leurs points de vue différents. En tant que partie intégrante des soins, l’espoir était un thème pour PSS. Les scores d’IEH étaient élevés, ce qui indique que les résidents étaient généralement optimistes. Les résultats de l’étude suggèrent que, pour le sous-groupe petit mais complexe de résidents en soins de longue durée qui a un diagnostic de cancer, l’espoir n’est pas perdu, mais plutôt il est pertinent, nuancé et possible d’atteindre.
Phylogenetic, molecular and drug-sensitivity analysis of HA and NA genes of human H3N2 influenza A viruses in Guangdong, China, 2007–2011
Authors: HUANG P. , LIANG L.-J. , HOU N.-M. , ZHANG X. , SU W.-Z. , YU S.-Y. , ZHANG Y.-H. , WU J. , CHEN W. Q.
Published: July 2012

Annual H3N2 subtype influenza outbreaks in Guangdong, China are a severe public health issue and require ongoing monitoring of emerging viral variants. The variation and evolution of haemagglutinin (HA) and neuraminidase (NA) genes of influenza isolates from Guangdong during 2007–2011 and others from GenBank were analysed using Lasergene 7.1 and MEGA 5.05, and serological analysis of antigens was determined by haemagglutination inhibition (HI). Susceptibility to antiviral drugs was correlated with genetic mutations. Phylogenetic analysis and alignment of HA and NA genes were performed on 18 Guangdong isolates and 26 global reference strains. The non-synonymous (dN) evolutionary rate of HA1 was 3·13 times that of HA2. Compared with the A/Perth/16/2009 vaccine HA gene, homologies of Guangdong isolates were between 98·8–99·7% and 98·0–98·4% in 2009 and 2010, respectively. Amino-acid substitutions were found in five epitopes of HA1 from Guangdong isolates between 2007 and 2011, especially in epitopes B (N160K) and D (K174R/N). The K189E/N/Q and T228A mutations in the receptor-binding site (RBS) occurred in the 2010 strains, which affected the antigenicity of HA1. The antigenicity of the epidemic H3N2 isolates in 2010 was somewhat different from that of A/Perth/16/2009. The Guangdong H3N2 isolates were determined to be oseltamivir-resistant with IC50of 0·396±0·085 nmol/l (n=17) and zanamivir-resistant with IC50of 0·477±0·149 nmol/l (n=18). Variations were present in epitopes B and D, two sites in the RBS and two glycosylation sites in the Guangdong H3N2 HA1 gene. The majority of the Guangdong H3N2 isolates were sensitive to oseltamivir and zanamivir. Compared to the World Health Organization 2012 vaccine strains, Guangdong H3N2 strains varied genetically and antigenically to some degree.
Asymmetries in international environmental agreements
Authors: Pavlova Yulia , de Zeeuw Aart
Published: July 2012

This paper considers self-enforcing international environmental agreements when countries are asymmetric with respect to emission-related benefits and environmental damage. Considering these asymmetries simultaneously yields large stable coalitions, also without the option of transfers between signatories. However, these large stable coalitions are only possible if they include countries that have relatively high marginal benefits and a relatively low marginal environmental damage. This type of countries hardly contributes to the common good and the gains of cooperation from including this type of countries in the stable coalition are small. This confirms a persistent result in this literature that large stable coalitions usually go hand in hand with low gains of cooperation. Without the option of transfers it is always better to have a small stable coalition with countries that matter than a large stable coalition with countries that do not matter. Only with transfers might a large stable coalition be able to perform better.
The opioid placebo analgesia is mediated exclusively through µ-opioid receptor in rat
Authors: Zhang Rui-Rui , Zhang Wen-Cai , Wang Jin-Yan , Guo Jian-You
Published: July 2012

Placebo analgesia is one of the most robust and best-studied placebo effects. Recent researches suggest that placebo analgesia activated the µ-opioid receptor signalling in the human brain. However, whether other opioid receptors are involved in the placebo analgesia remains unclear. We have previously evoked placebo responses in mice (Guo et al.2010, 2011) and these mice may serve as a model for investigating placebo analgesia. In the present study, we tried to explore the site of action and types of opioid receptors involved in placebo response. Male Sprague–Dawley rats were trained with 10 mg/kg morphine for 4 d to establish the placebo analgesia model. This placebo analgesia can be blocked by injection of 5 mg/kg dose naloxone or by microinjection with naloxone (1, 3 or 10 µg/rat) into rostral anterior cingulate cortex (rACC). Then, animals were tested after intra-rACC microinjection of d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP, a selective µ-opioid receptor antagonist) or naltrindole (NTI, a highly selective δ-opioid receptor antagonist) or nor-binaltorphimine (nor-BNI, a highly selective κ-opioid receptor antagonist). Our results showed that CTOP, but not NTI or nor-BNI, could reduce the pain threshold in placebo analgesia rats. It may be concluded that rACC is the key brain region involved in placebo analgesia and the opioid placebo analgesia is mediated exclusively through µ-opioid receptor in rat.
A statistical study of magnetopause structures: Tangential versus rotational discontinuities
Authors: Chou Y.‐C. , Hau L.‐N.
Published: July 2012

A statistical study of the structure of Earth's magnetopause is carried out by analyzing two‐year AMPTE/IRM plasma and magnetic field data. The analyses are based on the minimum variance analysis (MVA), the deHoffmann‐Teller (HT) frame analysis and the Walén relation. A total of 328 magnetopause crossings are identified and error estimates associated with MVA and HT frame analyses are performed for each case. In 142 out of 328 events both MVA and HT frame analyses yield high quality results which are classified as either tangential‐discontinuity (TD) or rotational‐discontinuity (RD) structures based only on the Walén relation: Events withSWA ≤ 0.4 (SWA ≥ 0.5) are classified as TD (RD), and rest (with 0.4 < SWA < 0.5) is classified as “uncertain,” where SWA refers to the Walén slope. With this criterion, 84% of 142 events are TDs, 12% are RDs, and 4% are uncertain events. There are a large portion of TD events which exhibit a finite normal magnetic field component Bnbut have insignificant flow as compared to the Alfvén velocity in the HT frame. Two‐dimensional Grad‐Shafranov reconstruction of forty selected TD and RD events show that single or multiple X‐line accompanied with magnetic islands are common feature of magnetopause current. A survey plot of the HT velocity associated with TD structures projected onto the magnetopause shows that the flow is diverted at the subsolar point and accelerated toward the dawn and dusk flanks.
Carbon and sediment accumulation in the Everglades (USA) during the past 4000 years: Rates, drivers, and sources of error
Authors: Glaser Paul H. , Volin John C. , Givnish Thomas J. , Hansen Barbara C. S. , Stricker Craig A.
Published: July 2012

Tropical and subtropical wetlands are considered to be globally important sources of greenhouse gases, but their capacity to store carbon is presumably limited by warm soil temperatures and high rates of decomposition. Unfortunately, these assumptions can be difficult to test across long timescales because the chronology, cumulative mass, and completeness of a sedimentary profile are often difficult to establish. We therefore made a detailed analysis of a core from the principal drainage outlet of the Everglades of South Florida in order to assess these problems and determine the factors that could govern carbon accumulation in this large subtropical wetland. Accelerator mass spectroscopy dating provided direct evidence for both hard‐water and open‐system sources of dating errors, whereas cumulative mass varied depending upon the type of method used. Radiocarbon dates of gastropod shells, nevertheless, seemed to provide a reliable chronology for this core once the hard‐water error was quantified and subtracted. Long‐term accumulation rates were then calculated to be 12.1 g m−2 yr−1 for carbon, which is less than half the average rate reported for northern and tropical peatlands. Moreover, accumulation rates remained slow and relatively steady for both organic and inorganic strata, and the slow rate of sediment accretion (0.2 mm yr−1) tracked the correspondingly slow rise in sea level (0.35 mm yr−1) reported for South Florida over the past 4000 years. These results suggest that sea level and the local geologic setting may impose long‐term constraints on rates of sediment and carbon accumulation in the Everglades and other wetlands.
The effects of floodplain soil heterogeneity on meander planform shape
Authors: Motta D. , Abad J. D. , Langendoen E. J. , García M. H.
Published: July 2012

Past analytical studies of meander planform development have mostly focused on the complexity of the governing equations, i.e., hydrodynamics, and less so on the stream bank resistance to erosion, whose spatial heterogeneity is difficult to describe deterministically. This motivated the use of a Monte Carlo approach to examine the effects of floodplain soils and their distribution on planform development, with the goal of including bank erosion properties in the analysis. Simulated bank erosion rates are controlled by the resistance to hydraulic erosion of the bank soils using an excess shear stress approach. The spatial distribution of critical shear stress across the floodplain is delineated on a rectangular, equidistant grid with varying degrees of variability. The corresponding erodibility coefficient is computed using a field‐derived empirical relation. For a randomly disturbed distribution, in which the mean resistance to erosion exponentially increases away from the valley centerline, two relevant parameters are identified: the standard deviation of the critical shear stress distribution, which controls skewness and variability of the channel centerline, and the cross‐valley increase in soil resistance, which constrains lateral migration and also affects bend skewness. For a purely random distribution, migrated centerlines exhibit larger variability for increasing spatial scales of floodplain soil heterogeneity. For equal stochastic variability of the corresponding governing parameters, relating meander migration to hydraulic erosion of the bank soils produces more variability and shape complexity than the “classic” bank migration approach of Ikeda et al. (1981), which relates migration rate to excess velocity at the outer bank. Finally, the proposed stochastic approach provides a foundation for estimating a suitable spatial density of measurements to characterize the physical properties of floodplain soils and vegetation.
The north‐south tilt in the Australian Height Datum is explained by the ocean's mean dynamic topography
Authors: Featherstone W. E. , Filmer M. S.
Published: July 2012

Using geodetic and oceanographic data, we show that the apparent north‐south slope between the Australian Height Datum (AHD) and the geoid is caused almost completely by the ocean's time‐mean dynamic topography (MDT). This is because the AHD was constrained to zero height at local mean sea level at multiple tide gauges around the Australian continent. Using MDT models and corrected leveling data, almost all of the apparent north‐south slope can be removed from the AHD. An auxiliary observation is that a satellite‐only MDT model based on only around one year of GOCE data generates results commensurate with geodetic, oceanographic and combined MDT models.
Why does the temperature rise faster in the arid region of northwest China?
Authors: Li Baofu , Chen Yaning , Shi Xun
Published: July 2012

During 1960–2010, the air temperature in the arid region of northwest China had a significant rising trend (P < 0.001), at a rate of 0.343°C/decade, higher than the average of China (0.25°C/decade) and that of the entire globe (0.13°C/decade) for the same period. Based on the analysis of the data from 74 meteorological stations in the region for 1960–2010, we found that among the four seasons the temperature change of winter has been playing the most important role in the yearly change in this region. We also found that the winter temperature in this region has a strong association with the Siberian High (correlation coefficient: R = −0.715) and the greenhouse gas emission (R = 0.51), and between the two the former is stronger. We thus suggest that the weakening of the Siberian High during the 1980s to 1990s on top of the steady increasing of the greenhouse emission is the main reason for the higher rate of the temperature rise in the arid region of the northwest China.
Neurovascular Uncoupling under Mild Hypoxic Hypoxia: An EEG–fMRI Study in Rats
Authors: Sumiyoshi Akira , Suzuki Hideaki , Shimokawa Hiroaki , Kawashima Ryuta
Published: July 2012

The effects of oxygen availability on neurovascular coupling were investigated using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), in addition to the monitoring of physiological parameters, in 16 α-chloralose-anesthetized rats. Mild hypoxic hypoxia (oxygen saturation=83.6±12.1%) induced significant reductions in fMRI responses ( P<0.05) to electrical stimulation in the forepaw, but EEG responses remained unchanged. In addition, the changes in oxygen saturation were linearly correlated with the changes in the fMRI responses. These data further emphasize the importance of oxygen availability, which may regulate neurovascular coupling via the oxygen-dependent enzymatic synthesis of messenger molecules.
A monochromatic x-ray imaging system for characterizing low-density foams
Authors: Lanier N. E. , Hamilton C. , Taccetti J. M.
Published: July 2012

In high energy density laser experiments, targets often require small, low-density, foam components. However, their limited size can preclude single component characterization, forcing one to rely solely on less accurate bulk measurements. We have developed a monochromatic imaging system to characterize both the density and uniformity of single component low-mass foams. This x-ray assembly is capable of determining line-averaged density variations near the 1% level, and provides statistically identical results to those obtained at the Brookhaven's NSLS. This system has the added benefit of providing two-dimensional density data, allowing an assessment of density uniformity.
Bounds on the number of bound states in the transfer matrix spectrum for some weakly correlated lattice models
Authors: O’Carroll Michael
Published: July 2012

We consider the interaction of particles in weakly correlated lattice quantum field theories. In the imaginary time functional integral formulation of these theories there is a relative coordinate lattice Schroedinger operator H which approximately describes the interaction of these particles. Scalar and vector spin, QCD and Gross-Neveu models are included in these theories. In the weakly correlated regime H = Ho + W where Ho = −γΔl, 0 < γ ≪ 1 and Δl is the d-dimensional lattice Laplacian: γ = β, the inverse temperature for spin systems and γ = κ3 where κ is the hopping parameter for QCD. W is a self-adjoint potential operator which may have non-local contributions but obeys the bound |W(x, y)| ⩽ cexp ( − a(|x| + |y|)), a large: $\exp \left( { - a} \right) = \left| {\beta /\beta _o } \right|^{\frac{1}{2}} (\left| {\kappa /\kappa _o } \right|)$exp−a=β/βo12(κ/κo) for spin (QCD) models. Ho, W, and H act in l2(Zd), d ⩾ 1. The spectrum of H below zero is known to be discrete and we obtain bounds on the number of states below zero. This number depends on the short range properties of W, i.e., the long range tail does not increase the number of states.
Micellization and relaxation in solution with spherical micelles via the discrete Becker–Döring equations at different total surfactant concentrations
Authors: Babintsev Ilya , Adzhemyan Loran , Shchekin Alexander
Published: July 2012

A numerical description of micellization and relaxation to an aggregate equilibrium in surfactant solution with nonionic spherical micelles has been developed on the basis of a discrete form of the Becker–Döring kinetic equations. Two different models for the monomer-aggregate attachment–detachment rates have been used, and it has been shown that the results are qualitatively the same. The full discrete spectrum of characteristic times of micellar relaxation and first relaxation modes in their dependence on equilibrium monomer concentration have been found with using the linearized form of the Becker–Döring kinetic equations. Overall time behavior of surfactant monomer and aggregate concentrations in micellization and relaxation at large initial deviations from final equilibrium has been studied with the help of nonlinearized discrete Becker–Döring kinetic equations. Comparison of the computed results with the analytical ones known in the limiting cases from solutions of the linearized and nonlinearized continuous Becker–Döring kinetic equation demonstrates general agreement.
Novel in situ normal streaming potential device for characterizing electrostatic properties of confluent cells
Authors: Vandrangi P. , Jreij P. , Rajapaksa T. E. , Bansal N. , Lo D. D. , Rodgers V. G. J.
Published: July 2012

The characteristics of transport across confluent cell monolayers may often be attributed to its electrostatic properties. While tangential streaming potential is often used to quantify these electrostatic properties, this method is not effective for transport normal to the apical cell surface where the charge properties along the basolateral sides may be important (i.e., confluent cells with leaky tight junctions). In addition, even when cells have a uniform charge distribution, the shear stress generated by the conventional tangential flow device may dislodge cells from their confluent state. Here we introduce a novel streaming potential measurement device to characterize the normal electrostatic properties of confluent cells. The streaming potential device encompasses a 24 mm cell-seeded Transwell® with two AgCl electrodes on either side of the cell-seeded Transwell. Phosphate buffered saline is pressurized transversal to the Transwell and the resultant pressure gradient induces a potential difference. Confluent monolayers of HEK and EA926 cells are used as examples. The corresponding zeta potential of the cell-membrane configuration is calculated using the Helmholtz–Smoluchowski equation and the zeta potential of the confluent cell layer is deconvolved from the overall measurements. For these test models, the zeta potential is consistent with that determined using a commercial dispersed-cell device. This novel streaming potential device provides a simple, easy, and cost-effective methodology to determine the normal zeta potential of confluent cells cultured on Transwell systems while keeping the cells intact. Furthermore, its versatility allows periodic measurements of properties of the same cell culture during transient studies.
A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude
Authors: Mao Jiubing , Wang Xin , Tang Dan , Lv Huayi , Li Chengxin , Shao Yanhua , Qin Lan
Published: July 2012

In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.
Four-body interaction energy for compressed solid krypton from quantum theory
Authors: Tian Chunling , Wu Na , Liu Fusheng , Saxena Surendra K. , Zheng Xingrong
Published: July 2012

The importance of the four-body contribution in compressed solid krypton was first evaluated using the many-body expansion method and the coupled cluster theory with full single and double excitations plus perturbative treatment of triples. All different four-atom clusters existing in the first- and second-nearest neighbor shells of face-centered cubic krypton were considered, and both self-consistent-field Hartree-Fock and correlation parts of the four-body interaction were accurately determined from the ambient conditions up to eightfold volume compression. We find that the four-body interaction energy is negative at compression ratio lower than 2, where the dispersive forces play a dominant role. With increasing the compression, the four-body contribution becomes repulsive and significantly cancels the over-softening effects of the three-body potential. The obtained equation of state (EOS) was compared with the experiments and the density-functional theory calculations. It shows that combination of the four-body effects with two- and three-body interactions leads to an excellent agreement with EOS measurements throughout the whole experimental range 0–130 GPa, and extends the prediction to 300 GPa.
Piezoelectricity in lead zirconate titanate nanowires: A theoretical study
Authors: Sen Banani , Stroscio Michael , Dutta Mitra
Published: July 2012

The piezoelectric coefficients for lead zirconate titanate (PZT) being an order of magnitude higher than the piezoelectric semiconductors, it is expected that this piezoceramic would be very promising for mechanical energy harvesting. This paper presents a systematic evaluation of the piezoelectric potential generated in charge-free PZT nanowires upon application of mechanical strain in different directions. Similar to wurtzite semiconductor nanowires, in case of PZT wires of rocksalt crystal structure, it is found that the stretching modes generate higher potential than the bending mode. However, in spite of high piezoelectric coefficients, the piezoelectric potential generated from these piezoceramic wires is much lower than the semiconductor nanowires because of their high dielectric constant.
Direct numerical simulation of binary off-center collisions of shear thinning droplets at high Weber numbers
Authors: Focke C. , Bothe D.
Published: July 2012

Binary droplet collisions, a prototype elementary subprocess inside sprays, are investigated by direct numerical simulations (DNS) based on an extended volume of fluid method. We focus on shear-thinning droplet collisions. In order to capture the dynamics of droplet collisions with different outcomes, we account for off-center collisions at high Weber numbers. Such collision conditions lead to the formation of extremely thin fluid lamellae. It turns out that these thin lamellae determine the smallest length scales which must be resolved in a DNS. A stabilization algorithm is presented which prevents the lamellae from rupturing. It is validated by comparison with experimental data and applied for a droplet collision study of shear-thinning liquids. The results show that, independent of the off-set of the colliding droplets, a collision of Newtonian liquid droplets with appropriately chosen viscosity can reproduce the collision dynamics of the shear-thinning liquid droplets. This includes temporal evolution of shapes and energy.
Faraday rotation effect in periodic graphene structure
Authors: Liu Daqing , Zhang Shengli , Ma Ning , Li Xinghua
Published: July 2012

We report the magneto-optical (MO) rotation effect in a periodic graphene-sheet structure. Due to the masslessness of carriers in graphene, the magnetic response is very sensitive and the magneto-optical rotation effect is therefore significant. We predict that the Verdet constant of the periodic graphene-sheet structure is roughly 10–100 times that of rare-earth-doped magneto-optical glass in the infrared region.
Energy dissipation and switching delay in stress-induced switching of multiferroic nanomagnets in the presence of thermal fluctuations
Authors: Roy Kuntal , Bandyopadhyay Supriyo , Atulasimha Jayasimha
Published: July 2012

Switching the magnetization of a shape-anisotropic 2-phase multiferroic nanomagnet with voltage-generated stress is known to dissipate very little energy (<1 aJ for a switching time of ∼0.5 ns) at 0 K temperature. Here, we show by solving the stochastic Landau-Lifshitz-Gilbert equation that switching can be carried out with ∼100% probability in less than 1 ns while dissipating less than 1.5 aJ at room temperature. This makes nanomagnetic logic and memory systems, predicated on stress-induced magnetic reversal, one of the most energy-efficient computing hardware extant. We also study the dependence of energy dissipation, switching delay, and the critical stress needed to switch, on the rate at which stress on the nanomagnet is ramped up or down.
Nonminimal operators and non-commutative residue
Authors: Wang Jian , Wang Yong
Published: July 2012

In this paper, we get the Kastler-Kalau-Walze type theorem associated to nonminimal operators by heat equation asymptotics on compact manifolds without boundary. We compute the lower-dimensional volume associated to nonminimal operators for five-dimensional compact manifolds with boundary and we also compute lower-dimensional volume associated to the De-Rham Hodge operators for six-dimensional compact manifolds with boundary.
A simply constructed but efficacious shock tester for high-g level shock simulation
Authors: Duan Zhengyong , Zhao Yulong , Liang Jing
Published: July 2012

A simply constructed shock tester, different from existing drop table machines, is developed for high-g level shock environment simulation. The theoretical model, structure design, and working principle of the drop tester are described. A prototype device is set up, where a carbon fiber reinforced polymer with a high specific modulus is used. Using a Brüel & Kjær high-g accelerometer, experiments to verify the validity of the design are carried out and results are given. The maximum acceleration level is in excess of 60 000 g, limited only by the manual driving force.
Influence of transverse fields on domain wall pinning in ferromagnetic nanostripes
Authors: Glathe S. , Hübner U. , Mattheis R. , Seidel P.
Published: July 2012

We report an experimental study dealing with the influence of in-plane transverse fields on the domain wall (DW) pinning in ferromagnetic nanostripes. We analyzed the pinning probability and depinning fields for several fabrication induced pinning sites. For all measurements reported here, the depinning field decreases with increasing transverse field independently from the actual domain wall type and the shape of the pinning site. The pinning probability decreases with increasing transverse fields for weak pinning sites. Stronger pinning sites can be active for large field ranges and show a complex dependence of the pinning probability on the applied transverse field. The occurrence of different domain wall types as well as the influence of a transverse field on the domain wall dynamics can explain this behavior.
Effect of coherent to incoherent structural transition on magnetic anisotropy in Co/Pt multilayers
Authors: Chowdhury P. , Kulkarni P. D. , Krishnan M. , Barshilia Harish C. , Sagdeo A. , Rai S. K. , Lodha G. S. , Sridhara Rao D. V.
Published: July 2012

The crystallographic structure and magnetic anisotropy have been investigated in Co/Pt multilayers deposited by direct current magnetron sputtering on two different buffer layers, Ta and Pt. Detail theoretical and experimental investigations reveal the presence of three effects: magneto-elastic, interface and shape anisotropies, and their competition results in three distinct regions based on the Co layer thickness (tCo). In the region I, with tCo< 6 Å, the coherent lattice strain modifies the volume anisotropy through magneto-elastic contribution and it leads to overall positive volume anisotropy energy. With further increase in tCo, lattice mismatch initiates and this results in a decrease in magneto-elastic effect and it enhances the interface anisotropy. The presence of both diminished magneto-elastic effect and enhanced interface anisotropy results in an intermediate region (region II) with negative volume anisotropy energy which is relatively wider (6 Å<tCo< 12 Å) for multilayer stacks with Ta underlayer. In the region III, with tCo> 12 Å, the magneto-elastic effect emerges as an interface phenomena and the shape anisotropy becomes dominant.
Single step channeling in glass interior by femtosecond laser
Authors: Kongsuwan Panjawat , Wang Hongliang , Lawrence Yao Y.
Published: July 2012

Channeling inside a transparent material, glass, by femtosecond laser was performed by using a single step process rather than hybrid processes that combine the laser irradiation with an additional tool or step to remove the material. Tightly focusing of a single femtosecond laser pulse using proper optical and laser processing parameters could induce the micro-explosion and could create voids inside transparent materials, and the effects of these parameters on the resultant feature geometry and channel length were studied. Understanding of the channel length variation at different locations from the specimen surface could enhance prediction capability. Taking into account of the laser, material, and lens properties, numerical models were developed to predict the absorption volume shape and size at different focusing depths below the surface of a specimen. These models will also be validated with the variation in feature and channel lengths inside the specimen obtained from the experiments. Spacing between adjacent laser pulses and laser parameters was varied to investigate effects of channel overlapping and its influence on long channel formation.
Steering and collimating ballistic electrons with amphoteric refraction
Authors: Radu A. , Dragoman D. , Iftimie S.
Published: July 2012

We show that amphoteric refraction of ballistic electrons, i.e., positive or negative refraction depending on the incidence angle, occurs at an interface between an isotropic and an anisotropic medium and can be employed to steer and collimate electron beams. The steering angle is determined by the materials’ parameters, but the degree of collimation can be tuned in a significant range by changing the energy of ballistic electrons.
Exact control of junction position using epitaxial NiSi2 crystallization in ultrathin silicon-on-insulator metal-oxide-semiconductor field-effect transistors
Authors: Mizubayashi W. , Migita S. , Morita Y. , Ota H.
Published: July 2012

This paper reports the demonstration of exact control of the junction position in ultrathin silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) using epitaxial NiSi2 crystallization. In the ultrathin SOI (100) plane, NiSi2 first grows in the <100> vertical direction and along the SOI/buried oxide (BOX) interface. Subsequently, NiSi2 grows in the <110> lateral direction and sustains a (111) facet. We found that epitaxial NiSi2 crystallization in ultrathin SOI proceeds first vertically, then laterally, in a step-by-step crystallization pattern. Epitaxial NiSi2 crystallization rates for the (100) and (111) planes are proportional to the root square of the annealing time associated with the lattice diffusion reaction. Thus, the junction position in an ultrathin SOI MOSFET with metal source/drain can be exactly controlled by annealing times.