bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal plasma and amniotic fluid angiogenic factors and their receptors in monochorionic twin pregnancies complicated by twin‐to‐twin transfusion syndrome
Authors: Fox C. E. , Lash G. E. , Pretlove S. J. , Chan B. C. , Holder R. , Kilby M. D.
Published: December 2009

Objective

Angiogenic factors play a role in human placentation and may be aberrant in severe twin‐to‐twin transfusion syndrome (TTTS). The aim of this study was to investigate the maternal plasma and amniotic fluid angiogenic factor and receptor concentrations in twin pregnancies complicated by TTTS and to evaluate the effects of fetoscopic laser ablation.

Methods

A prospective cohort of monochorionic (MC) twins complicated by severe TTTS (n = 23) was studied between October 2006 and December 2007. A cohort of uncomplicated dichorionic (DC) (n = 12) and MC (n = 7) pregnancies were studied for comparison. Circulating angiogenic factors and their receptors were measured in the maternal plasma and the recipient twin's amniotic fluid by enzyme‐linked immunosorbent assay and/or FAST Quant human angiogenesis array.

Results

Plasma vascular endothelial growth factor (VEGF)‐C concentrations were significantly lower in TTTS than in uncomplicated twin pregnancies (P < 0.0001). In contrast, plasma angiopoietin (Ang)‐2 levels and the ratio of soluble vascular endothelial growth factor receptor‐1 (sVEGFR‐1) to placental growth factor (PlGF) levels were significantly increased in TTTS (P < 0.01). Plasma VEGF‐D was significantly increased in advanced stage TTTS (Stage III/IV cohort; P < 0.01). This was independent of fetal size, amniotic fluid volumes or the number of apparent placental arteriovenous anastomoses. In TTTS pregnancies, amniotic fluid VEGF‐C, VEGF‐A, Ang‐1 and the sVEGFR‐1/PlGF ratio were increased compared to paired maternal plasma concentrations (P < 0.0001) while amniotic fluid concentrations of PlGF, Ang‐2 and soluble tyrosine kinase with immunoglobulin‐like/epidermal growth factor‐like domains 2 (sTie‐2) were significantly lower than plasma concentrations (P < 0.0001). No significant association between maternal plasma and amniotic fluid concentrations of angiogenic factors was noted. Plasma PlGF was transiently decreased after fetoscopic laser ablation, returning to baseline by 1 week (P = 0.0314). Fetoscopic laser ablation also affected plasma sVEGFR‐1/PlGF ratio with a transient increase after therapy, followed by a significant reduction to below basal concentrations by 1 week (P = 0.0102). Only VEGF‐D was significantly different (+8.3%; P = 0.0155) in amniotic fluid immediately after the completion of fetoscopic laser ablation.

Conclusion

Maternal angiogenic activity is decreased in severe TTTS, with an increased sVEGFR‐1/PlGF ratio and concentrations of Ang‐2 and VEGF‐D in the maternal plasma compared to uncomplicated MC twin pregnancies. Maternal circulating PlGF concentrations decrease and the sVEGFR‐1/PlGF ratio increases transiently in response to fetoscopic laser ablation, but in general the angiogenic factor and receptor concentrations studied are altered little by this therapy. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Birth‐weight prediction by two‐ and three‐dimensional ultrasound imaging
Authors: Bennini J. R. , Marussi E. F. , Barini R. , Faro C. , Peralta C. F. A.
Published: December 2009

Objectives

To compare the accuracies of birth‐weight predicting models derived from two‐dimensional (2D) ultrasound parameters and from total fetal thigh volumes measured by three‐dimensional (3D) ultrasound imaging; and to compare the performances of these formulae with those of previously published equations.

Methods

A total of 210 patients were evaluated to create a formula‐generating group (n = 150) and a prospective‐validation group (n = 60). Polynomial regression analysis was performed on the first group to generate one equation based on 2D ultrasound measurements, one based on fetal thigh volume measured by the multiplanar technique (ThiM) and one based on fetal thigh volume obtained by the Virtual Organ Computer‐aided AnaLysis (VOCAL™) method (ThiV). Paired‐samples t‐tests with Bonferroni adjustments were used to compare the performances of these equations in the formula‐finding and the prospective‐validation groups. The same approach was used to compare the accuracies of the new 2D and 3D formulae with those of both original and modified 2D equations from previous publications, as well as the 3D model reported by Chang et al.

Results

The formulae with the best fit for the prediction of birth weight were: estimated fetal weight (EFW) = − 562.824 + 11.962× AC × FDL + 0.009 × BPD2× AC2 (where AC is abdominal circumference, FDL is femur diaphysis length and BPD is biparietal diameter), EFW = 1033.286 + 12.733 × ThiM, and EFW = 1025.383 + 12.775 × ThiV. For both the formula‐generating and the prospective‐validation groups, there were no significant differences between the accuracies of the new 2D and 3D models in the prediction of birth weight. When applied to our population, the performances of the modified and original versions of the previously published 2D equations and the performance of the original 3D formula reported by Chang et al. were all significantly worse than our models.

Conclusions

We believe that the greatest sources of discrepancy in estimation of birth weight are the phenotypic differences among patients used to create each of the formulae mentioned in this study. Our data reinforce the need for customized birth‐weight prediction formulae, regardless of whether 2D or 3D measurements are employed. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Properties of high‐temperature‐resistant drilling fluids incorporating acrylamide/(acrylic acid)/(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) terpolymer and aluminum citrate as filtration control agents
Authors: Peng Bo , Peng Shangping , Long Bo , Miao Yongjing , Guo Wen‐Yu
Published: December 2009

A terpolymer of acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) was synthesized by a free‐radical solution polymerization technique, characterized by FTIR methods, and applied together with aluminum citrate in oilfield drilling as a high‐temperature‐resistant filtration control agent. Before and after thermal aging for 16 h at 180°C, the combined effect of the terpolymer and aluminum citrate on the Bingham‐type rheological and fluid‐loss properties of the corresponding fresh‐water and salt‐water muds was further investigated. The results showed that before the thermal aging, there was a similar changing trend in the rheological and fluid‐loss properties of the muds with terpolymer concentration, regardless of the presence of aluminum citrate. After the thermal aging, some hydrophilic polycomplexes of AM‐AA‐AMPS terpolymer with aluminum citrate may have been formed and consequently inhibited viscosity loss of the muds, thereby improving the fluid‐loss properties. A possible mechanism is proposed to explain the improvement. J. VINYL ADDIT. TECHNOL, 2010. © 2009 Society of Plastics Engineers
Wind tunnel test on airfoil Risø‐B1‐18 with an Active Trailing Edge Flap
Authors: Bak Christian , Gaunaa Mac , Andersen Peter B. , Buhl Thomas , Hansen Per , Clemmensen Kasper
Published: December 2009

A wind tunnel test of the wind turbine airfoil Risø‐B1‐18 equipped with an Active Trailing Edge Flap (ATEF) was carried out. The ATEF was 9% of the total chord, made of piezo electric actuators attached to the trailing edge of a non‐deformable airfoil and actuated using an (electric) amplifier. The airfoil was tested at Re = 1.66 × 106. Steady state and dynamic tests were carried out with prescribed deflections of the ATEF. The steady state tests showed that deflecting the ATEF towards the pressure side (positive β) translated the lift curve to higher lift values and deflecting the ATEF towards the suction side (negative β) translated the lift curve to lower lift values. Testing the airfoil for a step change of the ATEF from β = −3.0 to +1.8 showed that the obtainable Δcl was 0.10 to 0.13 in the linear part of the lift curve. Modeling the step response with an indicial function formulation showed that the time constant in the step change and in sinusoidal deflections in dimensionless terms was T0* = 0.6. Testing the ability of the ATEF to cancel out the load variations for an airfoil in sinusoidal pitch motion of ΔAOA = ±0.7 showed that it was possible to reduce the amplitude with around 80% from Δcl = 0.148 to Δcl = 0.032. Copyright © 2009 John Wiley & Sons, Ltd.
Simulation of wind turbine wake interaction using the vorticity transport model
Authors: Fletcher Timothy M. , Brown Richard E.
Published: December 2009

The aerodynamic interactions that can occur within a wind farm can result in the constituent turbines generating a lower power output than would be possible if each of the turbines were operated in isolation. Tightening of the constraints on the siting of wind farms is likely to increase the scale of the problem in the future. The aerodynamic performance of turbine rotors and the mechanisms that couple the fluid dynamics of multiple rotors can be most readily understood by simplifying the problem and considering the interaction between only two rotors. The aerodynamic interaction between two rotors in both co‐axial and offset configurations has been simulated using the Vorticity Transport Model. The aerodynamic interaction is a function of the tip speed ratio, and both the streamwise and crosswind separation between the rotors. The simulations show that the momentum deficit at a turbine operating within the wake developed by the rotor of a second turbine is governed by the development of instabilities within the wake of the upwind rotor, and the ensuing structure of the wake as it impinges on the downwind rotor. If the wind farm configuration or wind conditions are such that a turbine rotor is subject to partial impingement by the wake produced by an upstream turbine, then significant unsteadiness in the aerodynamic loading on the rotor blades of the downwind turbine can result, and this unsteadiness can have considerable implications for the fatigue life of the blade structure and rotor hub. Copyright © 2009 John Wiley & Sons, Ltd.
Development and Evaluation of an Observational Tool for Assessing Surgical Flow Disruptions and Their Impact on Surgical Performance
Authors: Parker Sarah E. Henrickson , Laviana Aaron A. , Wadhera Rishi K. , Wiegmann Douglas A. , Sundt Thoralf M.
Published: December 2009

Background

Many researchers have previously explored the correlation between surgical flow disruptions and adverse events in cardiac surgery; however, there is no reliable tool to prospectively categorize surgical flow disruptions and the conditions that predispose a surgical team to adverse events.

Methods

Two independent raters of different medical and human factors expertise observed 12 cardiovascular operations and iteratively designed a surgical flow disruption tool (SFDT) to characterize surgical flow disruptions and the latent factors that contribute to adverse events. Categories to characterize surgical flow disruptions were created based on human factors models of human error. After the design period, both raters observed ten surgical cases using the tool to assess validity and inter‐rater reliability.

Results

Rating agreement (weighted kappa) for each category across the ten surgeries was moderate to very high, resulting in strong inter‐rater reliability for each category on the surgical flow disruption tool. Use of the SFDT was simple and clear for observers of diverse backgrounds, including human factors experts and medical personnel.

Conclusions

This research depicts the development and utility of a tool to analyze surgical flow disruptions in the cardiovascular operating room with satisfactory inter‐rater reliability. This tool is an important first step in systematically categorizing and measuring surgical flow disruptions and their impact on patient safety in the operating room.
Some Imidazoline Derivatives as Corrosion Inhibitors
Authors: Aiad Ismail Abdelrhman , Hafiz A. A. , El‐Awady M. Y. , Habib A. O.
Published: December 2009

In this study, cationic surfactants having different alkyl chain lengths were prepared by amidation of lauric, myristic, palmitic, stearic, oleic acids with diethylene triamine. The products were quaternized using chloroacetic acid. The chemical structure of the prepared compounds was elucidated using different spectroscopic techniques. The critical micelle concentration (CMC) and the free energy of the micellization and adsorption of these compounds were determined by surface tension and conductivity measurements. The products were evaluated as surface‐active agents as well as corrosion inhibitors for steel alloy in 1 M hydrochloric and sulfuric acid, the results indicate that these materials have a high efficiency as corrosion inhibitors and as surface active agents. These results were correlated with the chemical structure of the prepared compounds.
Dynamic early Holocene vegetation development on the Faroe Islands inferred from high-resolution plant macrofossil and pollen data
Authors: Hannon Gina E. , Rundgren Mats , Jessen Catherine A.
Published: December 2009

Vegetation dynamics during the earliest part of the Holocene (11,250"10,250"cal yr BP) have been reconstructed from a lacustrine sequence on Sandoy, the Faroe Islands, using detailed plant macrofossil and pollen evidence. The plant macrofossils suggest the initial vegetation was sparse herb and shrub tundra, with Salix herbacea and open-ground species, followed by the development of a denser and more species-rich arctic heathland after 11,150"cal yr BP. Despite high pollen values for Betula nana, macrofossils are rare. The bulk of the macrofossils recorded are S. herbacea and Empetrum leaves with numerous herb taxa and an abundance of Racomitrium moss. Conditions start to change around 10,800"cal yr BP, with increased catchment erosion and sediment delivery to the lake from ca. 10,600"cal yr BP, and a transition to alternating Cyperaceae and Poaceae communities between ca. 10,450 and 10,250"cal yr BP. This vegetation change, which has been recorded throughout the Faroes, has previously been interpreted as a retrogressive shift from woody shrubs to a herbaceous community. The detailed plant macrofossil data show the shift is the replacement of an Empetrum arctic heathland by grassland and moist sedge communities. These taxa dominate the modern landscape.
Shock-resolved Navier–Stokes simulation of the Richtmyer–Meshkov instability start-up at a light–heavy interface
Authors: KRAMER R. M. J. , PULLIN D. I. , MEIRON D. I. , PANTANO C.
Published: December 2009

The single-mode Richtmyer–Meshkov instability is investigated using a first-order perturbation of the two-dimensional Navier–Stokes equations about a one-dimensional unsteady shock-resolved base flow. A feature-tracking local refinement scheme is used to fully resolve the viscous internal structure of the shock. This method captures perturbations on the shocks and their influence on the interface growth throughout the simulation, to accurately examine the start-up and early linear growth phases of the instability. Results are compared to analytic models of the instability, showing some agreement with predicted asymptotic growth rates towards the inviscid limit, but significant discrepancies are noted in the transient growth phase. Viscous effects are found to be inadequately predicted by existing models.
Taxonomic significance of tunic spicules in photosymbiotic ascidians: a quantitative and molecular evaluation
Authors: Hirose Mamiko , Tochikubo Tetsuya , Hirose Euichi
Published: December 2009

Many didemnid ascidians have calcareous spicules in the tunic. Since the spicules of each species have a specific shape and size-range, they are often regarded as an important character for taxonomy. To evaluate the taxonomic significance of tunic spicules, a quantitative survey of spicule size and shape was combined with a molecular phylogeny inferred from the partial sequence of the cytochrome c oxidase subunit I (COI) gene in some groups of didemnid species that are supposedly closely related. This study revealed the presence of substantial intraspecific variations in the shape and size of tunic spicules. The spicules are, therefore, not always crucial features discriminating species, particularly among related species. Although tunic spicules are potentially valuable features for didemnid taxonomy, their intraspecific variation should be carefully considered before they are used as a key character for species identification.
First record of the Levantine species Scoloplos haasi (Orbiniidae: Scolecida: Annelida) from the Mediterranean coast of Spain
Authors: López Eduardo
Published: December 2009

During an investigation devoted to characterize all the Orbiniidae polychaete species present in the Iberian Peninsula, several individuals previously identified as Scoloplos armiger showed to actually belong to Scoloplos haasi, a species to date considered endemic from Israel. The comparison with the holotype deposited in the British Museum of Natural History confirmed the identification. This record of S. haasi is not only a new one for the western Mediterranean but also the first one out of its original locality, extending largely westwards the geographical range of the species.
Ivory gulls breeding on ice
Authors: Boertmann David , Olsen Kent , Gilg Oliver
Published: December 2009

A breeding colony of ivory gulls was discovered on an ice floe in northeast Greenland in August 2008. The ice floe resembled nearby islands in that it was covered with a thick layer of gravely moraine, and furthermore its position was fixed throughout most of the breeding season as the surrounding first year ice only broke up in mid August when most of the gull chicks had fledged.
Serial slaughter: the development of the north Norwegian sealing fleet: 1859–1909
Authors: Kjær Kjell-G.
Published: December 2009

This paper describes the growth and development of the sealing industry of northern Norway from 1859 to 1909 and is based largely on hunting returns and shipping records of the Tromsø fleet. Arctic hunting operations displayed remarkable diversity across the years and the ascendancy of sealing only emerged towards the end of the 19th century. The paper shows how the fleet increased in size despite the lack of capital in northern Norway for investment in new vessels and how hunting grew in significance as a commercial operation following the introduction of modern hunting techniques and better weapons. The fleet increased almost eightfold, from 6 vessels in 1859 to 46 in 1909 while the harvest of seals increased from less than 1500 to over 30000 animals annually. The geographical range of the hunting grounds expanded correspondingly from a limited area around Jan Mayen and the west coast of Spitsbergen to a huge area which included the western ice (north and south of Jan Mayen), the northern ice (Svalbard), the eastern ice (Kola Peninsula to Novaya Zemlya, the White Sea), Zemlya Frantsa-Isoifa [Franz Joseph Land], the Denmark Strait and northeast Greenland. The species composition of the harvest underwent a remarkable series of transitions, one species being replaced by another as local stocks became successively depleted. Thus, it was dominated numerically first by Svalbard reindeer and walrus, then beluga whales and then cod before finally consisting largely of polar bears, bottlenose whales and seals. Owners and skippers responded to reductions in numbers by searching for new hunting grounds and, in doing so, sailed further north, then east and then west than ever before, coincidentally making a series of historical voyages of discovery. By the end of these five decades sloops had largely been replaced by ketch rigged diesel sealers, these being an assortment of new, salvaged and second hand foreign ships.
Subanesthetic dose of ketamine decreases prefrontal theta cordance in healthy volunteers: implications for antidepressant effect
Authors: Horacek J. , Brunovsky M. , Novak T. , Tislerova B. , Palenicek T. , Bubenikova-Valesova V. , Spaniel F. , Koprivova J. , Mohr P. , Balikova M. , Hoschl C.
Published: December 2009

Background

Theta cordance is a novel quantitative electroencephalography (QEEG) measure that correlates with cerebral perfusion. A series of clinical studies has demonstrated that the prefrontal theta cordance value decreases after 1 week of treatment in responders to antidepressants and that this effect precedes clinical improvement. Ketamine, a non-competitive antagonist ofN-methyl-d-aspartate (NMDA) receptors, has a unique rapid antidepressant effect but its influence on theta cordance is unknown.

Method

In a double-blind, cross-over, placebo-controlled experiment we studied the acute effect of ketamine (0.54 mg/kg within 30 min) on theta cordance in a group of 20 healthy volunteers.

Results

Ketamine infusion induced a decrease in prefrontal theta cordance and an increase in the central region theta cordance after 10 and 30 min. The change in prefrontal theta cordance correlated with ketamine and norketamine blood levels after 10 min of ketamine infusion.

Conclusions

Our data indicate that ketamine infusion immediately induces changes similar to those that monoamineric-based antidepressants induce gradually. The reduction in theta cordance could be a marker and a predictor of the fast-acting antidepressant effect of ketamine, a hypothesis that could be tested in depressive patients treated with ketamine.
High Neuroticism and low Conscientiousness are associated with interleukin-6
Authors: Sutin A. R. , Terracciano A. , Deiana B. , Naitza S. , Ferrucci L. , Uda M. , Schlessinger D. , Costa P. T.
Published: December 2009

Background

High Neuroticism and low Conscientiousness are frequently implicated in health-risk behaviors, such as smoking and overeating, as well as health outcomes, including mortality. Their associations with physiological markers of morbidity and mortality, such as inflammation, are less well documented. The present research examines the association between the five major dimensions of personality and interleukin-6 (IL-6), a pro-inflammatory cytokine often elevated in patients with chronic morbidity and frailty.

Method

A population-based sample (n=4923) from four towns in Sardinia, Italy, had their levels of IL-6 measured and completed a comprehensive personality questionnaire, the NEO-PI-R. Analyses controlled for factors known to have an effect on IL-6: age; sex; smoking; weight; aspirin use; disease burden.

Results

High Neuroticism and low Conscientiousness were both associated with higher levels of IL-6. The findings remained significant after controlling for the relevant covariates. Similar results were found for C-reactive protein, a related marker of chronic inflammation. Further, smoking and weight partially mediated the association between impulsivity-related traits and higher IL-6 levels. Finally, logistic regressions revealed that participants either in the top 10% of the distribution of Neuroticism or the bottom 10% of conscientiousness had an approximately 40% greater risk of exceeding clinically relevant thresholds of IL-6.

Conclusions

Consistent with the literature on personality and self-reported health, individuals high on Neuroticism or low on Conscientiousness show elevated levels of this inflammatory cytokine. Identifying critical medical biomarkers associated with personality may help to elucidate the physiological mechanisms responsible for the observed connections between personality traits and physical health.
Integrating Legal Research Skills into the Curriculum and into Life
Authors: Pope Alison
Published: December 2009

Alison Pope explains how Staffordshire University Law School has redesigned its legal research module, with emphasis placed on information literacy and with careful timetabling to ensure the module is embedded in the curriculum.
Managing Change in Difficult Times
Authors: Holbeche Linda
Published: December 2009

Linda Holbeche discusses how knowledge and service industry organisations should change in recessionary periods and she explains the cycle of change.
At the Heart of Justice: the Library at the new Supreme Court of the United Kingdom
Authors: Rowe Jenny
Published: December 2009

The new Supreme Court of the United Kingdom, which heard its first case in October 2009, sits at the apex of the UK's justice systems. Located in the painstakingly restored Grade II Listed Middlesex Guildhall in Parliament Square, it will be the highest appeal court in England, Wales and Northern Ireland and for civil cases in Scotland. Jenny Rowe, Chief Executive of the Court, reveals how the new Justices' Library is at the heart of this landmark building.
Opening up the UK's Foreign and International Law Collections: the FLARE Initiative, the FLAG Foreign Law Guide and the FLARE Index to Treaties
Authors: Swift Hester , Clinch Peter
Published: December 2009

Hester Swift, Foreign and International Law Librarian, Institute of Advanced Legal Studies, and Peter Clinch, Senior Subject Librarian for Law, Cardiff University delivered this paper at the recent BIALL Annual Conference.
US Legal Information
Authors: Swift Hester
Published: December 2009

This survey of United States law sources, by Hester Swift, Foreign and International Law Librarian, Institute of Advanced Legal Studies, is based on a presentation delivered at the BIALL Foreign and International Law Seminar on 3 March 2009.
Legal Information Management Readers' Survey
Authors: O'Rourke Rebecca
Published: December 2009

This article by Rebecca O'Rourke, Commissioning Editor, Humanities and Social Sciences Journals, Cambridge University Press discusses the results of the recent survey carried out by CUP on our behalf to see whether LIM is still relevant to our readers.
Essential or “Nice to Have”? The Impact of the Financial Downturn on KM in Law Firms
Authors: Small Wendy
Published: December 2009

Wendy Small considers the potentially far-reaching changes in the structure of law firms in the light of the recession and advises information professionals on how they should reconsider the nature of the services they offer to ensure that they remain business critical.
Good Breeding? Hybrid Professionals and the Thriving Library – a Law Firm Perspective
Authors: Stanfield Kate
Published: December 2009

Kate Stanfield has based this article on a presentation given at the 2008 Online meeting. She considers the potential role of the non-traditionally trained information professional within a law firm information service. Such roles include professional support lawyers, para-legals and business development and IT professionals.
“A Sensible Radical”: Conversations with Professor Sir Bob Hepple. Part 2 - UK and the World
Authors: Dingle Lesley
Published: December 2009

This is a further contribution to the Squire Law Library Eminent Scholars Archive based on interviews with Emeritus Professor Sir Bob Hepple.1 Part 2 covers his career in the UK, both academic and as a legal activist in the fields of human and social rights and labour law. Professor Hepple gave his interviews at the Squire Law Library between August 2007 and June 2008.
A Rookie Law Librarian Visits the Institute of Advanced Legal Studies
Authors: Schriwer Tania
Published: December 2009

Tania Schriwer, a lawyer who is retraining as a law librarian, describes a three-week visit from her home library school at the University of Washington in Seattle to the IALS.
Optimization of circular antenna arrays of isotropic radiators using simulated annealing
Authors: Rattan Munish , Patterh M.S. , Sohi B.S.
Published: December 2009

This paper presents the design optimization of circular antenna arrays of isotropic radiators using simulated annealing. The problem has been formulated to achieve a desired value of sidelobe level and a minimum possible value of beamwidth. This is accomplished by jointly optimizing the excitation amplitude and spacing between elements. Simulation examples have been given and comparison has been carried out with particle swarm optimization method.
GDNF and MAPK–ERK pathway signaling is reduced during nephrogenesis following maternal under-nutrition
Authors: Henry T. Q. , Mansano R. Z. , Nast C. C. , Lakshmanan J. , Abdallah M. , Abdel-Hakeem A. K. , Desai M. , Ross M. G. , Magee T. R.
Published: December 2009

Maternal under-nutrition (MUN) during gestation results in growth-restricted newborns with reduced glomerular number and subsequent hypertension. We investigated dysregulation of glial derived neurotrophic factor (GDNF) and MAPK–ERK (mitogen-activated protein kinase–extracellular signal-regulated protein kinase) signal pathway gene expression following MUN. MUN rats were 50% food restricted from embryonic day 10 till postnatal day 1. Kidneys were harvested at embryonic day (E)20, and postnatal days (P)1 and 21. Kidney protein expression was determined by Western blot. At E20, protein expression of growth factor receptor alpha 1 (GFRα1) and phosphorylated ERK1/2 and mitogen-activated protein kinase kinase (MEK)1/2 were reduced significantly, and immunohistochemistry confirmed reduction of phosphorylated ERK (pERK) with maintenance of pERK localization. Total MEK and ERK were unchanged. At P1, only GFRα1 and pERK1/2 were reduced significantly while at P21, expression of all growth factors except total MEK was unchanged. Total MEK was increased. Glomerular number was decreased by 19% in P21 kidneys and blood pressure was increased in 12-week-old rats. In conclusion, GDNF and MAPK–ERK signaling are dysregulated during active nephrogenesis in fetal and early newborn offspring kidneys in the MUN model. This may be a key mechanism in reduced offspring nephrogenesis and programmed hypertension.
Mechanical buckling of single-walled carbon nanotubes: Atomistic simulations
Authors: Chang I-Ling , Chiang Bing-Chen
Published: December 2009

Various geometric sizes and helical types (i.e., armchair, zigzag, and chiral) of single-walled carbon nanotubes (CNTs) are considered in molecular dynamics simulations in order to systematically examine the length-to-radius ratio and chirality effects on the buckling mechanism. The buckling strain is getting smaller as the CNT becomes slender for most nanotubes, which implies that the slender nanotubes have lower buckling resistance regardless of the radius of the CNTs. The applicability of the continuum buckling theory, which has been well developed for thin tubes, on predicting the buckling strain of the CNT is also examined. In general, the corresponding buckling strain and buckling type predicted by the continuum buckling theory could agree reasonably well with simulation results except at the transition region due to the competition of two buckling mechanisms.
A new soft x-ray pulse height analysis array in the HL-2A tokamak
Authors: Zhang Y. P. , Liu Yi , Yang J. W. , Song X. Y. , Liao M. , Li X. , Yuan G. L. , Yang Q. W. , Duan X. R. , Pan C. H.
Published: December 2009

A new soft x-ray pulse height analysis (PHA) array including nine independent subsystems, on basis of a nonconventional software multichannel analysis system and a silicon drift detector (SDD) linear array consisting of nine high performance SDD detectors, has been developed in the HL-2A tokamak. The use of SDD has greatly improved the measurement accuracy and the spatiotemporal resolutions of the soft x-ray PHA system. Since the ratio of peak to background counts obtained from the SDD PHA system is very high, p/b≧3000, the soft x-ray spectra measured by the SDD PHA system can approximatively be regarded as electron velocity distribution. The electron velocity distribution can be well derived in the pure ohmic and auxiliary heating discharges. The performance of the new soft x-ray PHA array and the first experimental results with some discussions are presented.
Low temperature growth of epitaxial graphene on SiC induced by carbon evaporation
Authors: Al-Temimy A. , Riedl C. , Starke U.
Published: December 2009

Low temperature growth of epitaxial graphene on SiC is facilitated by carbon evaporation under ultrahigh vacuum (UHV) conditions. By counteracting the need for complete Si depletion as in the conventional sublimation method, monolayer graphene evolves at significantly lower temperatures by depositing additional carbon, so that a degradation of the initial SiC surface quality can be avoided. The original, well ordered terrace structure of SiC(0001) is preserved, the graphene layers grow on top and show the typical linear π-band dispersion. On SiC(0001¯) the graphene lattice is rotated by 30° in comparison to the conventional UHV preparation method.
Defect modes in one-dimensional anisotropic photonic crystal
Authors: Ouchani N. , Bria D. , Djafari-Rouhani B. , Nougaoui A.
Published: December 2009

We theoretically analyze the defect states in a single-defect photonic crystal composed of anisotropic dielectric materials. This structure can trap light of a given frequency range and filter only a certain frequency light. It is shown that the defect modes appear as peaks in the transmission spectrum. Their numbers, intensities, and frequency positions are extremely sensitive to the incidence angle and the orientation of the principal axes of layers constituting the superlattice and the layer defect. Our structure offers a great variety of possibilities for creating and controlling the number and transmitted intensities of defect modes. It can be a good candidate for realizing a selective electromagnetic filter.
Studies of the fragmentation of the monocation and dication of methanol
Authors: Douglas Kevin M. , Price Stephen D.
Published: December 2009

Relative partial ionization cross sections and precursor-specific relative partial ionization cross sections for fragment ions formed by electron ionization of methanol have been measured using time-of-flight mass spectrometry coupled with a two-dimensional ion coincidence technique. Relative cross sections are reported for ionizing energies from 30 to 200 eV. Good agreement is found between our data and one set of recently published absolute partial ionization cross sections. Conversely, discrepancies are observed with another set of recently published data; we attribute these discrepancies to the loss of translationally energetic fragment ions. Our precursor-specific cross sections allow the contribution from single and double ionization to the individual fragment ion yields, following ionization of methanol, to be quantified for the first time. Our analysis shows that the contribution of double ionization to the total ion yield reaches a maximum of 20% between 150 and 200 eV.
Dynamics of excimer formation and decay in supercritical krypton
Authors: Holroyd Richard A. , Cook Andrew R. , Preses Jack M.
Published: December 2009

New infrared absorbing species are identified in the pulse radiolysis of supercritical Kr at high pressures. The species are believed to be excimers. Their formation and decay rates have been time resolved using the Laser Electron Accelerator Facility. An initial species, formed in less than 1 ns, absorbs at several wavelengths between 790 and 1300 nm; The decay of this species is initially fast, followed by a slower component; the decay rate increases with pressure. As this initial species decays a second excimer is formed absorbing at 830, 890, and 990 nm. The growth and decay rates of this excimer are also pressure dependent. A third excimer, absorbing between 1000 and 1200 nm grows at a rate similar to that of the decay of the second species. The decay rate of the third species is also pressure dependent; the lifetime increases from 9.4 ns at 109 bar to 49 ns at 15 bar. A kinetic mechanism is proposed that satisfactorily reproduces the experimental results. The first species is identified as a higher energy gerade triplet state excimer and the second as the singlet gerade state.
Shubnikov–de Haas oscillations in an individual single-crystalline bismuth nanowire grown by on-film formation of nanowires
Authors: Shim Wooyoung , Ham Jinhee , Kim Jungmin , Lee Wooyoung
Published: December 2009

Shubnikov–de Haas (SdH) oscillations have been investigated in an individual Bi nanowire grown by on-film formation of nanowires that is a growth method producing extremely high-quality single-crystalline nanowires. The variation of observed SdH oscillations with transverse and longitudinal magnetic fields to the axis of the Bi nanowire is qualitatively consistent with the geometry of the highly anisotropic Fermi surfaces of Bi, and in turn, reveals the growth direction of the nanowires and demonstrates the high crystal quality. Our results demonstrate the vast potential of high-quality single-crystalline Bi nanowires for a variety of device applications and for fundamental investigations such as quantum transport.
The effect of ac field amplitude on the relaxor behaviors in Langmuir–Blodgett terpolymer films
Authors: Meng X. J. , Wang J. L. , Xu H. S. , Sun J. L. , Chu J. H.
Published: December 2009

The ac field (Eac) amplitude dependence of dielectric response has been investigated for poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) relaxor terpolymer films. The frequency dependence of the temperature of the permittivity maximum Tm can be well described by the Vogel–Fulcher relation for Eac in the range from 1.33 to 80 MV/m. Tm remains nearly constant at an Eac level lower than 13.3 MV/m, and starts decreasing with Eac increases further. The two parameters fitting to the Vogel–Fulcher relation, freezing temperature Tf and activation energy Ea, vary little for Eac below 26.7 MV/m and then Tf decreases, while Ea increases for higher Eac level.
Strain-driven self-rolling mechanism for anomalous coiling of multilayer nanohelices
Authors: Dai L. , Shen W. Z.
Published: December 2009

We have proposed a comprehensive model based on a Cosserat curve to investigate the strain-driven self-rolling mechanism for anomalous coiling of multilayer nanohelices from the biaxial-torque point of view. Special attention has been paid to the edge effects, which dominate the anomalous coiling and decrease the helicity angles to as small as 0. By quantitatively explaining the experiments, we have demonstrated that the edge effects not only generate the torsion torque, together with the initial stress perpendicular to the preferential winding direction, to turn the nanobelts, but also offset part of the initial uniaxial bent torque. Our derived expressions can be used experimentally to determine the geometry of multilayer nanohelices with all helicity angles. The present work has provided useful information for the future experimental investigation on multilayer nanohelices as well as their application in meta-/quantum-devices.
Proximity effect and interface transparency in Nb/Cu multilayers
Authors: Kushnir V. N. , Prischepa S. L. , Cirillo C. , Attanasio C.
Published: December 2009

The interface transparency T is quantitatively studied in Nb/Cu multilayers. The dependence of the critical temperature Tc on both the thickness of superconducting layers dS in Cu/Nb/Cu trilayers and on the number of Nb/Cu bilayers Nb in Cu/[Nb/Cu]Nb multilayers is considered. The experimental results are analyzed on the base of the exact solution of Usadel equations. We obtain that there is an infinite number of pairs of (T,ξN) (ξN being the normal metal coherence length) which describes the measured Tc(dS) dependence with the same accuracy. This degeneracy is removed if the experimental Tc(Nb) dependence is analyzed. This allows to unambiguously determine, without the need of an independent estimation of ξN, the value of T for our system. This general method turns out to be especially useful when dealing with superconducting/normal metal hybrids for which microscopic parameters are not well determined.
Heteronuclear double resonance in nuclear magnetic resonance spectroscopy: Relaxation of multiple-quantum coherences
Authors: Ulzega Simone , Verde Mariachiara , Ferrage Fabien , Bodenhausen Geoffrey
Published: December 2009

Theoretical and experimental investigations of the relaxation rates of multiple-quantum coherences during heteronuclear double resonance (HDR) pulse sequences are presented. Average Liouvillian theory yields analytical expressions to describe the effective relaxation rates of multiple-quantum coherences during HDR irradiation. Experiments were carried out on a C13–H1 pair in glycerol to measure the effective auto- and cross-relaxation rates of multiple-quantum coherences during HDR schemes. The experimental results exhibit a very good agreement with theoretical predictions, even when the average Liouvillian expansion is truncated to zeroth order.
Jerky elasticity: Avalanches and the martensitic transition in Cu74.08Al23.13Be2.79 shape-memory alloy
Authors: Salje Ekhard K. H. , Koppensteiner Johannes , Reinecker Marius , Schranz Wilfried , Planes Antoni
Published: December 2009

Jerky elasticity was observed by dynamical mechanical analyzer measurements in a single crystal of the shape memory alloy Cu74.08Al23.13Be2.79. Jerks appear as spikes in the dissipation of the elastic response function and relate to the formation of avalanches during the transformation between the austenite and the martensite phase. The statistics of the avalanches follows the predictions of avalanche criticality P(E)∝E−ε where P(E) is the probability of finding an avalanche with the energy E. This result reproduces, within experimental uncertainties, previous findings by acoustic emission techniques.
Quantitative measurement of the surface charge density
Authors: Johann Florian , Soergel Elisabeth
Published: December 2009

We present a method of measuring the charge density on dielectric surfaces. Similar to electrostatic force microscopy we record the electrostatic interaction between the probe and the sample surface, but at large tip-sample distances. For calibration we use a pyroelectric sample which allows us to alter the surface charge density by a known amount via a controlled temperature change. For proof of principle, we determined the surface charge density under ambient conditions of ferroelectric lithium niobate.
A lower bound to the survival probability and an approximate first passage time distribution for Markovian and non-Markovian dynamics in phase space
Authors: Chakrabarti Rajarshi , Sebastian K. L.
Published: December 2009

We derive a very general expression of the survival probability and the first passage time distribution for a particle executing Brownian motion in full phase space with an absorbing boundary condition at a point in the position space, which is valid irrespective of the statistical nature of the dynamics. The expression, together with the Jensen’s inequality, naturally leads to a lower bound to the actual survival probability and an approximate first passage time distribution. These are expressed in terms of the position-position, velocity-velocity, and position-velocity variances. Knowledge of these variances enables one to compute a lower bound to the survival probability and consequently the first passage distribution function. As examples, we compute these for a Gaussian Markovian process and, in the case of non-Markovian process, with an exponentially decaying friction kernel and also with a power law friction kernel. Our analysis shows that the survival probability decays exponentially at the long time irrespective of the nature of the dynamics with an exponent equal to the transition state rate constant.
Density functional method including weak interactions: Dispersion coefficients based on the local response approximation
Authors: Sato Takeshi , Nakai Hiromi
Published: December 2009

A new method to calculate the atom-atom dispersion coefficients in a molecule is proposed for the use in density functional theory with dispersion (DFT-D) correction. The method is based on the local response approximation due to Dobson and Dinte [Phys. Rev. Lett. 76, 1780 (1996)], with modified dielectric model recently proposed by Vydrov and van Voorhis [J. Chem. Phys. 130, 104105 (2009)]. The local response model is used to calculate the distributed multipole polarizabilities of atoms in a molecule, from which the dispersion coefficients are obtained by an explicit frequency integral of the Casimir–Polder type. Thus obtained atomic polarizabilities are also used in the damping function for the short-range singularity. Unlike empirical DFT-D methods, the local response dispersion (LRD) method is able to calculate the dispersion energy from the ground-state electron density only. It is applicable to any geometry, free from physical constants such as van der Waals radii or atomic polarizabilities, and computationally very efficient. The LRD method combined with the long-range corrected DFT functional (LC-BOP) is applied to calculations of S22 weakly bound complex set [Phys. Chem. Chem. Phys. 8, 1985 (2006)]. Binding energies obtained by the LC-BOP+LRD agree remarkably well with ab initio references.
Investigating the regrowth surface of Si:P δ-layers toward vertically stacked three dimensional devices
Authors: McKibbin S. R. , Clarke W. R. , Fuhrer A. , Reusch T. C. G. , Simmons M. Y.
Published: December 2009

We investigate the surface quality of encapsulated Si:P δ-layers for the fabrication of multilayer devices with the potential to create architectures with sub 20 nm resolution in all three spatial dimensions. We use scanning tunneling microscopy to investigate how the dopant incorporation chemistry of the first active layer strongly affects the quality of the Si encapsulation which serves as the regrowth interface for the second active layer. Low temperature Hall measurements of the encapsulated layers indicate full dopant activation for incorporation temperatures between 250–750 °C with 20% higher carrier densities than previously observed.