bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrothermal Synthesis of NdIII Doped Bi2Se3 Nanoflowers and their Physical Properties
Authors: Alemi Abdolali , Babalou Aliakbar , Dolatyari Mahboubeh , Klein Axel , Meyer Gerd
Published: June 2009

Luminescent Bi2–xNdxSe3 nanoplates and nanoflowers were prepared by a hydrothermal co‐reduction method. XRD patterns indicate that the Bi2–xNdxSe3 crystals with 0–10 mol‐% Nd3+ are isostructural with Bi2Se3. Preferential nucleation and growth of the synthesised Bi2–xNdxSe3 has been observed along a certain plane. SEM shows morphology changes upon doping of Nd3+ ions into bismuth sites from separate nano‐plates to nano‐flowers. UV/Vis spectra show that an increasing concentration of Nd3+ ions increases the intensity of some peaks in the absorption spectrum of Bi2Se3. Also, there is a red shift in the Bi2Se3 absorption peaks upon increased Nd3+ concentration. Photoluminescence spectra also show this shift. TG curves show two phase transformation steps for Bi2Se3 and Bi1.8Nd0.2Se3. One endothermic peak for the decomposition of the Nd3+ doped system is observed in the DTA curve of Bi1.8Nd0.2Se3.
Perforated Peptic Ulcer in South India: An Institutional Perspective
Authors: Arveen Sankar , Jagdish Sadasivan , Kadambari Dharanipragada
Published: June 2009

Background

Perforated peptic ulcer is one of the most common surgical emergencies in South India. The advent of medical therapy for peptic ulcer has remarkably decreased the number of elective surgical procedures. The incidence of perforated peptic ulcer on the contrary, is increasing. The high incidence of complications necessitates the identification of factors associated with the morbidity and mortality of patients undergoing surgery for perforated peptic ulcer.

Methods

Three hundred twenty‐eight consecutive patients (299 men and 29 women) who underwent surgery for perforated peptic ulcer in our institute between November 2006 and June 2008 were studied prospectively.

Results

The mean age was 43.4 ± 14.4 years. The mean hospital stay was 10.9 ± 6.8 days. Of the 328 patients, 58 presented with shock, 159 presented with delay more than 24 h, and 24 had co‐morbid illness. Wound infection and intra‐abdominal abscess were encountered in 12.5% and 13.4% of the patients, respectively. Altogether, 85 patients had postoperative complications. Twenty‐eight (8.5%) patients died. The mortality rate among men and women was 7.9% and 20.7%, respectively. Age ≥ 60 years, lag period longer than 24 h, presence of co‐morbid illness, and shock at presentation were identified as independent predictors of postoperative complications. Shock at presentation, presence of co‐morbid illness, American Society of Anesthesiologists (ASA) grade III or more, and renal failure were identified as independent predictors of mortality.

Conclusions

Decreasing the delay in intervention and improving access to medical care may improve the outcome of patients undergoing surgery for perforated peptic ulcer. High‐risk patients are those who present with shock and co‐morbid illness.
Individual fertility differences in the frozen‐thawed spermatozoa among semen donors in the Labrador Retriever
Authors: Suwa Yoshinori , Abe Yasuyuki , Lee Dong Soo , Ueta Yoshiko Yanagimoto , Suzuki Hiroshi
Published: June 2009

Purpose

We aimed to validate and determine the possible application of transcervical insemination of frozen semen for improved breeding in guide dogs for the blind in Japan.

Methods

From February 2004 to March 2007, a total of 53 Labrador Retriever bitches, used for the breeding of guide dogs for the blind, were transcervically inseminated with frozen‐thawed semen from 13 males by means of a cystoscope.

Results

The overall whelping and pregnancy rate with the frozen semen was 42%. Pregnancy rates ranged widely from 0 to 100% depending on the semen donor male. Of 13 males, 6 males exhibited severely poor fertility (less than 20% pregnancy rate) and 3 males exhibited high fertility (over 70% pregnancy rate) on artificial insemination. However, the spermatozoa motility after thawing was not significantly different among these dogs. In addition, heterospermic insemination revealed the optimal timing for transcervical insemination with frozen‐thawed semen to be by day 6 after the LH surge.

Conclusions

Although transcervical insemination of frozen‐thawed semen is effective for breeding of guide dogs for the blind, some modification of freeze‐thawing procedures might be required to overcome individual fertility differences in the frozen‐thawed spermatozoa among semen donor dogs,. In addition, the motility of spermatozoa after thawing might not be an appropriate indicator of the relative fertility of frozen‐thawed spermatozoa in dogs.
How many heads are better than one? The reliability and validity of teenagers' self‐ and peer assessments
Authors: Sung Yao‐Ting , Chang Kuo‐En , Chang Tzyy‐Hua , Yu Wen‐Cheng
Published: June 2009

Self‐ and peer assessments are becoming more popular in classrooms, but there are few data on the reliability and validity of such assessments performed by school children. Because these factors are greatly affected by the number of raters, we conducted two studies to determine the rating behaviours of teenagers in self‐ and peer assessments, and how the number of raters influences the reliability and validity of self‐ and peer assessments. The first study involved 116 seventh graders (the first grade of middle school), where students individually playing musical recorders were subject to self‐ and peer assessments. The second study involved 110 eighth graders, with Web pages constructed by students being subject to self‐ and peer assessments. Generalizability theory and criterion‐related validity were used to obtain the reliability and validity coefficients of the self‐ and peer ratings. Analyses of variance were used to compare differences in self‐ and peer ratings between low‐ and high‐achieving students. The coefficients of reliability and validity increased with the number of raters in both studies, reaching the acceptable levels of 0.80 and 0.70, respectively, with 3 or 4 raters in the first study (involving assessments of individual performance) and with 14–17 raters in the second study (involving assessments of group work). Furthermore, low‐ and high‐achieving students tended to over‐ and underestimate the quality of their work in self‐assessment, respectively. The discrepancy between the ratings of students and experts was higher in group‐work assessments then in individual‐work assessments. The results have both theoretical and practical implications for researchers and teachers.
Heme‐dependent autophosphorylation of a heme sensor kinase, ChrS, from Corynebacterium diphtheriae reconstituted in proteoliposomes
Authors: Ito Yoko , Nakagawa Shoko , Komagata Ayako , Ikeda-Saito Masao , Shiro Yoshitsugu , Nakamura Hiro
Published: June 2009

Corynebacterium diphteriae employs the response regulator, ChrA, and the sensor kinase, ChrS, of a two‐component signal transduction system to utilize host heme iron. Although ChrS is predicted to encode a heme sensor, the sensing mechanism remains to be characterized. In this report, ChrS expressed in Eshcherichia coli membranes was solubilized and purified using decylmaltoside. ChrS protein incorporated into proteoliposomes catalyzed heme‐dependent autophosphorylation by ATP. Other metalloporphyrins and iron did not stimulate kinase activity. The UV–Vis spectrum of hemin in the ChrS–proteoliposomes indicated that heme directly interacts with ChrS. This is the first functional reconstitution of a bacterial heme‐sensing protein.
Endocytosis, asymmetric cell division, stem cells and cancer: Unus pro omnibus, omnes pro uno
Authors: Fürthauer Maximilian , González-Gaitán Marcos
Published: June 2009

Carcinogenesis can be initiated in adult stem cells, suggesting that tumours arise as a consequence of stem‐cell dysfunction. In the fruitfly, cancer arises in stem cells that fail to undergo asymmetric cell division. In flies and mammals, a specific regulation of the endocytic trafficking machinery allows stem cells to self‐renew and generate the differentiating cells required to form and maintain mature organs. We review recent findings suggesting that an understanding of the relationship between endocytosis, asymmetric cell division, stem cells and cancer will be crucial to unravel the cell biological basis of tumourigenesis.
IS MIGRATION STATUS A DETERMINANT OF URBAN NUTRITION INSECURITY? EMPIRICAL EVIDENCE FROM MUMBAI CITY, INDIA
Authors: CHOUDHARY NEETU , PARTHASARATHY D.
Published: June 2009

From an economic perspective that understood it as a spillover of development, migration is now also the subject of socioeconomic investigation incorporating the problems of assimilation, relative deprivation and isolation. The corollary is an increased emphasis on economic and social understanding of migration and its consequences. This entails studying migration or migrants in terms of factors beyond income. Health outcome is important among these non-income factors but at the same time remains less studied. Although there have been a few influential studies on health issues as linked to migration status, the issue of malnutrition in this context continues to be under-researched. This paper explores, theoretically and empirically, migration status and malnutrition in Mumbai in India. An econometric analysis of Demographic and Health Survey data gives insight into the dynamics of child and maternal undernutrition as mediated by migration status in Mumbai.
Health technology assessment in Denmark: Strategy, implementation, and developments
Authors: Sigmund Helga , Kristensen Finn Børlum
Published: June 2009

Objectives: The mainly tax-paid healthcare system in Denmark is decentralized with three defined policy and management levels. Health technology assessment (HTA) as a concept was introduced in the beginning of the 1980s. Significant implementation only happened when the first national strategy for HTA was developed by relevant stakeholders and issued as an official document in 1996. The introduction and the further development are described.

Methods: The Danish Institute for HTA was established in the National Board of Health in 1997 with responsibility for coordination and production of HTA. A local government reform from 2007 provides several new challenges to HTA and its coordination.

Results: An external evaluation in 2003 indicated that HTA was widely disseminated and that HTA results were benefitting political, administrative, and clinical decision making at all levels of the healthcare system.

Conclusions: The first national strategy for HTA, the broad HTA model covering four elements: Technology (clinical aspects), Patient, Organization, and Economy, and the development and introduction of mini-HTA as a tool for HTA-related activities in institutions and municipalities are major contributions to international HTA.
The incidence, management and consequence of tinnitus in older adults
Authors: Holmes Susan , Padgham Nigel D
Published: June 2009

Impaired hearing is prevalent amongst older people, adversely affecting physical and psychosocial function and, hence, quality of life. It may also cause depression. Yet evidence suggests that hearing problems are all too often regarded as a ‘normal’ part of ageing and more likely to be ignored than diagnosed and/or treated; many believe that little can be done to improve hearing. Furthermore,‘many of the behaviours of a hearing-impaired individual (e.g. irritability, inattention or inappropriate responses) may be interpreted as evidence of dementia’though they may simply reflect communication difficulties that can, in turn, damage personal relationships.
Poles ofL-functions and theta liftings for orthogonal groups
Authors: Ginzburg David , Jiang Dihua , Soudry David
Published: June 2009

In this paper, we prove that the first occurrence of global theta liftings from any orthogonal group to either symplectic groups or metaplectic groups can be characterized completely in terms of the location of poles of certain Eisenstein series. This extends the work of Kudla and Rallis and the work of Moeglin to all orthogonal groups. As applications, we obtain results about basic structures of cuspidal automorphic representations and the domain of holomorphy of twisted standardL-functions.
The myelin proteolipid DMalpha in fishes
Authors: Brösamle Christian
Published: June 2009

Vertebrate myelin membranes are compacted and held in close apposition by three structural proteins of myelin, myelin basic protein, myelin protein zero (MPZ) and myelin proteolipid protein (PLP1/DMalpha). PLP1/DMalpha is considered to function as a scaffolding protein and play a role in intracellular trafficking in oligodendrocytes. In humans, point mutations, duplications or deletions of PLP1 are associated with Pelizaeus–Merzbacher disease and spastic paraplegia Type 2. PLP1 is highly conserved between mammals, but less so in lower vertebrates. This has led some researchers to question whether certain fish species express PLP1 orthologues at all, and to suggest that the function of PLP1/DMalpha in the central nervous system (CNS) may have been taken over by MPZ. Here, we review the evidence for the conservation of orthologues of PLP1/DMalpha in actinopterygian fishes and provide a comparison of currently available sequence data across 17 fish species. Our analysis demonstrates that orthologues of PLP1/DMalpha have been retained and are functionally expressed in many, if not all, extant species of bony fish. Many of the amino acids that, when mutated, are associated with severe CNS pathology are conserved in teleosts, demonstrating conservation of essential functions and justifying the development of novel disease models in species such as the zebrafish.
Can a control model approach assist case formulation in psychotherapy?
Authors: Spratt Christopher G. , Carey Timothy A.
Published: June 2009

This paper looks at issues regarding case formulation in psychotherapy. Case formulation is well recognized as being helpful in the conceptualizing of psychological problems and as a useful tool in the practice of cognitive therapy. Control, as opposed to behaviour, is increasingly being seen as that human process most relevant to psychopathology. We look at the diagnosis and treatment of a small number of people, treated in a naturalistic setting, who were selected without any specific criteria other than being people whose problems were treated using the Method of Levels, a form of cognitive therapy based on the principles of Perceptual Control Theory, and who completed both pre- and post-treatment questionnaires. We then consider how the problems these people presented with, and their treatment, might be formulated as a result of taking this approach.
A critical evaluation of the role of cognitive behaviour therapy in children and adolescents with depression
Authors: Delaney Maura
Published: June 2009

Depressive disorders are relatively common in adolescents although less so in younger children. They accrue significant morbidity and frequent long-term sequelae as well as increased suicide risk in sufferers. Evidence-based treatment of depression in children and adolescents is the subject of intense investigation and debate. This article reviews the current evidence base for cognitive behaviour therapy in this group and makes recommendations for further areas of research.
Reverse convection potential: A statistical study of the general properties of lobe reconnection and saturation effects during northward IMF
Authors: Sundberg K. Å. T. , Cumnock J. A. , Blomberg L. G.
Published: June 2009

The saturation tendency of the cross‐polar potential for southward interplanetary magnetic fields (IMFs) has been the subject of numerous studies; however, the behavior of the reverse convection potential when the IMF is northward remains less clear. In this study, we present a thorough statistical analysis of the four‐cell convection pattern associated with northward IMF and lobe reconnection based on a large set of DMSP F13 satellite data. Results show a behavior much similar to the southward IMF case, with a clear saturation tendency of the reverse convection potential for strong solar wind electric fields both seen in the data and validated in the statistical analysis. The saturated potential level reaches a limit of about 60 kV, on the order of a fourth of the saturated potential seen for dayside reconnection during southward IMF.
Analysis of geomagnetic sudden impulses at low latitudes
Authors: Villante U. , Piersanti M.
Published: June 2009

We present an analysis of the SI characteristics atλ≈ 36° examining 54 events for a 5‐year interval (2000–2004). In the H component, the ground responses are typically greater than expected for changes of the magnetopause current; they are also accompanied by significant changes of the D component. Both these aspects suggest a remarkable, long‐lasting contribution of the ionospheric currents on geomagnetic measurements associated with changes of the solar wind pressure. The relative response (i.e., as normalized to the change of the square root of the solar wind pressure) exhibits a local time modulation, with highest values in the afternoon hours for both components. For the H component, the average ratio between the observed and the predicted response is ≈1.5 in the central part of the day and ≈1.2 in the dark sector.
Seasonal modification of the Arctic Ocean intermediate water layer off the eastern Laptev Sea continental shelf break
Authors: Dmitrenko Igor A. , Kirillov Sergey A. , Ivanov Vladimir V. , Woodgate Rebecca A. , Polyakov Igor V. , Koldunov Nikolay , Fortier Louis , Lalande Catherine , Kaleschke Lars , Bauch Dorothea , Hölemann Jens A. , Timokhov Leonid A.
Published: June 2009

Through the analysis of observational mooring data collected at the northeastern Laptev Sea continental slope in 2004–2007, we document a hydrographic seasonal signal in the intermediate Atlantic Water (AW) layer, with generally higher temperature and salinity from December–January to May–July and lower values from May–July to December–January. At the mooring position, this seasonal signal dominates, contributing up to 75% of the total variance. Our data suggest that the entire AW layer down to at least 840 m is affected by seasonal cycling, although the strength of the seasonal signal in temperature and salinity reduces from 260 m (±0.25°C and ±0.025 psu) to 840 m (±0.05°C and ±0.005 psu). The seasonal velocity signal is substantially weaker, strongly masked by high‐frequency variability, and lags the thermohaline cycle by 45–75 days. We hypothesize that our mooring record shows a time history of the along‐margin propagation of the AW seasonal signal carried downstream by the AW boundary current. Our analysis suggests that the seasonal signal in the Fram Strait Branch of AW (FSBW) at 260 m is predominantly translated from Fram Strait, while the seasonality in the Barents Sea branch of AW (BSBW) domain (at 840 m) is attributed instead to the seasonal signal input from the Barents Sea. However, the characteristic signature of the BSBW seasonal dynamics observed through the entire AW layer leads us to speculate that BSBW also plays a role in seasonally modifying the properties of the FSBW.
Long‐term middle atmospheric influence of very large solar proton events
Authors: Jackman Charles H. , Marsh Daniel R. , Vitt Francis M. , Garcia Rolando R. , Randall Cora E. , Fleming Eric L. , Frith Stacey M.
Published: June 2009

The Whole Atmosphere Community Climate Model (WACCM3) has been used to study the long‐term (more than a few months) effects of solar proton events (SPEs). Extremely large solar proton events occurred in 1972, 1989, 2000, 2001, and 2003 and caused some longer‐lasting atmospheric changes. The highly energetic solar protons produced odd hydrogen (HOx) and odd nitrogen (NOy), which then led to ozone variations. Some statistically significant long‐term effects on mesospheric ozone were caused by the HOx increases due to a very active time period for SPEs (years 2000–2004), even though the HOx increases were short‐lived (days). The long‐term stratospheric ozone effects were caused by the NOy enhancements. Very large NOy enhancements lasted for months in the middle and lower stratosphere after a few of the largest SPEs. SPE‐caused NOy increases computed with WACCM3 were statistically significant at the 95% level throughout much of the polar stratosphere and mesosphere in the recent solar maximum 5‐year period (2000–2004). WACCM3‐computed SPE‐caused polar stratospheric ozone decreases of >10% continued for up to 5 months past the largest events; however, statistically significant ozone decreases were computed for only a relatively small fraction of this time in relatively limited altitudes in the lower mesosphere and upper stratosphere. Annually averaged model output showed statistically significant (to 95%) stratospheric ozone loss in the polar Northern Hemisphere for years 2000–2002. The computed annually averaged temperature and total ozone change in these years were not statistically significant.
Predicting fractional bed load transport rates: Application of the Wilcock‐Crowe equations to a regulated gravel bed river
Authors: Gaeuman David , Andrews E. D. , Krause Andreas , Smith Wes
Published: June 2009

Bed load samples from four locations in the Trinity River of northern California are analyzed to evaluate the performance of the Wilcock‐Crowe bed load transport equations for predicting fractional bed load transport rates. Bed surface particles become smaller and the fraction of sand on the bed increases with distance downstream from Lewiston Dam. The dimensionless reference shear stress for the mean bed particle size (τ*rm) is largest near the dam, but varies relatively little between the more downstream locations. The relation between τ*rm and the reference shear stresses for other size fractions is constant across all locations. Total bed load transport rates predicted with the Wilcock‐Crowe equations are within a factor of 2 of sampled transport rates for 68% of all samples. The Wilcock‐Crowe equations nonetheless consistently under‐predict the transport of particles larger than 128 mm, frequently by more than an order of magnitude. Accurate prediction of the transport rates of the largest particles is important for models in which the evolution of the surface grain size distribution determines subsequent bed load transport rates. Values of τ*rm estimated from bed load samples are up to 50% larger than those predicted with the Wilcock‐Crowe equations, and sampled bed load transport approximates equal mobility across a wider range of grain sizes than is implied by the equations. Modifications to the Wilcock‐Crowe equation for determining τ*rm and the hiding function used to scale τ*rm to other grain size fractions are proposed to achieve the best fit to observed bed load transport in the Trinity River.
Modeling Paleobathymetry in the Southern Ocean
Authors: Hayes Dennis E. , Zhang C. , Weissel R. A.
Published: June 2009

About 200 million years ago, the landmass that would eventually become Antarctica was temperate and was a part of the Gondwana supercontinent. Shifting plates gradually brought the proto‐Antarctic continent to a near‐polar latitude roughly 100 million years ago. However, the present‐day ice sheet that blankets the continent did not begin to form until about 35 million years ago. Although a polar position was presumed necessary to support continental glaciation, it clearly was not a sufficient one.
Looking to the Future
Authors: Grove Timothy L.
Published: June 2009

A year ago, AGU established the Future Focus Task Force (FFTF), a 15‐member committee to advise the AGU Council on three areas to strengthen AGU's ability to execute its strategic plan. The FFTF has been taking a broad look at the Union's structure and governance, the alignment of resources and the activities supported by these resources, and the capacities we need to develop to achieve our mission and long‐term goals while maintaining ourselves as a preeminent scientific society.

The FFTF also is taking important steps in preparing for the succession in headquarters leadership (see Eos, 90(5), 40, 2009, and 90(18), 159, 2009). This planning should help us in selecting the best candidate for AGU's next executive director. It also will give the search committee a clear understanding of where the Union intends to go and what leadership characteristics are needed to get us there.
Correction [to “New maps of California to improve tsunami preparedness”]
Authors: Anonymous
Published: June 2009

In the 21 April issue (Eos, 90(16), 2009), the article titled “New maps of California to improve tsunami preparedness” contained an error in its Figure 2 caption.
Today's Forecast: Higher Thinking With a Chance of Conceptual Growth
Authors: Cervato C. , Gallus W. , Boysen P. , Larsen M.
Published: June 2009

Weather has all the characteristics of a motivating, authentic subject: Everybody has an interest in it and strong opinions about it. This interest has provided a way to tie science to a meaningful learning activity in an introductory meteorology course for nonscience students. The pedagogical foundation of such a course is that it is more important for students in science classes to learn to think like scientists than to accumulate facts; weather forecasting allows them to progressively apply their knowledge about the atmosphere by hypothesizing the next day's weather. By forecasting tomorrow's weather repeatedly throughout the course, students are given the opportunity to link what they are learning in class to a topic to which they all relate.
Anticipating the Next Large Silent Earthquake in Mexico
Authors: Cotte Nathalie , Walpersdorf Andrea , Kostoglodov Vladimir , Vergnolle Mathilde , Santiago Jose‐Antonio , Campillo Michel
Published: June 2009

Silent earthquakes, or slow slip events (SSEs), in subduction zones [Schwartz and Rokosky, 2007] release accumulated strain energy within tens of minutes to a few months, as opposed to a few seconds or minutes for “regular” earthquakes [Kostoglodov et al., 2003]. This phenomenon has important implications for the seismic cycle because SSEs significantly modify the loading‐unloading budget of faults; their existence suggests that the buildup and relaxing mechanisms of the earthquake cycle are much more complex than previously thought.

Numerous important questions have to be answered concerning SSEs, in particular, their specific location on the fault, the amount of slip at depth, and their recurrence. Depending on whether they occur on the seismogenic or creeping section of the fault, they may release some accumulated elastic strain or further load the brittle part of the fault, effectively lengthening or shortening the time before the next large regular earthquake. In that framework, assessing the repartition of the displacement on the subduction interface and the frequency of SSEs is of particular importance, because these parameters govern the extent to which SSEs may slow or accelerate the regular earthquake clock.
Observations and modeling of particle dispersion signatures at a hot flow anomaly
Authors: Tjulin A. , Lucek E. A. , Dandouras I.
Published: June 2009

We analyze a hot flow anomaly (HFA) event that the Cluster spacecraft encountered on 22 April 2008. HFAs are regions of hot, highly deflected ion flow near planetary bow shocks that are created from interactions between tangential discontinuities in the solar wind and the bow shock. This HFA event is studied in detail because it is flanked by suprathermal ion beams that contain signatures of particle dispersion and where the particles have a nongyrotropic distribution. The composition of the beam ions is similar to that of the solar wind, and it implies that the beams consist of reflected solar wind plasma. The particle pitch angles in the beam are found to evolve over time so that the pitch angle decreases closer to the discontinuity. A simple model of particle motion at a tangential discontinuity is developed, which successfully predicts many of the observed features of the particle beams. The model also shows that the best conditions for formation of similar beams occur when the field rotation in the tangential discontinuity corresponding to the HFA is between 25° and 40° in the case where the magnetic field magnitude is the same on both sides of the discontinuity. The particle beams are coincident with observations of “1‐Hz waves” that are frequently found in the foreshock region. On the leading side of the HFA event, these waves are shown to be generated by the beam, while on the trailing side, the properties of the waves indicate that they are whistler waves generated at the bow shock through electron dynamics and propagating upstream. The second mechanism is the standard one that has been used to explain most observations of the 1‐Hz waves in the literature.
Extraction and characterization of the rhesus macaque T‐cell receptor β‐chain genes
Authors: Greenaway Hui Yee , Kurniawan Monica , Price David A , Douek Daniel C , Davenport Miles P , Venturi Vanessa
Published: June 2009

Rhesus macaque models have been instrumental in the development and testing of vaccines before human studies and have provided fundamental insights into the determinants of immune efficacy in a variety of infectious diseases. However, the characterization of antigen‐specific T‐cell receptor (TCR) repertoires during adaptive immune responses in these models has earlier relied on human TCR gene assignments. Here, we extracted and characterized TCR β‐chain (TRB) genes from the recently sequenced rhesus macaque genome that are homologous to the human TRB genes. Comparison of the rhesus macaque TRB genes with the human TRB genes showed an average best match similarity of 92.9%. Furthermore, we confirmed the usage of most rhesus macaque TRB genes by expressed TCRβ sequences within epitope‐specific TCR repertoires. This primary description of the rhesus macaque TRB genes will provide a standardized nomenclature and enable better characterization of TCR usage in studies that use this species.
X chromosome reactivation perturbs intracellular self/not‐self discrimination
Authors: Forsdyke Donald R
Published: June 2009

New reports indicate a chromosomal rather than hormonal basis for the susceptibility of females to autoimmune disease. It is held that if females reactivate an inactivated X chromosome, there will be overexpression of certain X‐located genes affecting immune function. Hence, normal mechanisms of self/not‐self discrimination might be impaired resulting in immune reaction to self antigens. However, the data are also consistent with the long‐held view that the demands of intracellular self/not‐self discrimination have driven the evolution of X‐chromosome dosage compensation. It was proposed that, whether cells are in male or female bodies, concentrations of proteins are fine‐tuned up to their aggregation thresholds. A disruption of this equilibrium, by agents originating either externally (for example, virus) or internally (for example, reactivated X chromosome), generates homoaggregates that trigger responses against the respective not‐self or self antigens. Thus, female susceptibility to autoimmune disease may not be because certain immune system genes happen to be X‐located, but because self/not‐self discrimination was the raison d'être for X‐chromosome dosage compensation in the first place.
Microscopic origins of the induced χ(2) in thermally poled phosphate glasses
Authors: Thamboon P. , Krol D. M.
Published: June 2009

We have investigated the microscopic origins of the induced χ(2) in two phosphate glasses: a self-prepared lanthanum phosphate glass with molar composition 0.2La2O3 0.8P2O5 and a commercial sodium alumino phosphate glass (IOG-1, Schott Glass Technologies, Inc.) with molar composition 0.6P2O5 0.24Na2O 0.13Al2O3 0.03Ce2O3. The drastic difference in alkali content in these two phosphate glass systems results in different origins of their induced χ(2). For the poled lanthanum phosphate glass, the origin of the induced χ(2), which is directly proportional to the dc field established inside the glass, is the result of charge migration. A model that uses a single-positive-charge carrier with a nonblocking cathode describes the anodic surface χ(2) of 30μm thickness. For the poled sodium alumino phosphate glass, two mechanisms—dipole reorientation via the applied field and charge migration—are responsible for the origin of the bulk and the surface χ(2). Dipole reorientation via the applied field is suggested for the bulk contribution, while a charge migration model that involves multiple-charge carriers with nonblocking electrodes is appropriate for the surface χ(2).
Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films
Authors: Chen C. Q. , Pei Y. T. , Shaha K. P. , De Hosson J. Th. M.
Published: June 2009

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a “microstructural ruler” that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens of nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.
Nontrivial systems and the necessity of the scalar quantum mechanics axioms
Authors: Kotůlek Jan
Published: June 2009

We discuss the necessity of the axioms of scalar quantum mechanics introduced by Paschke and clearly demonstrate their geometric and/or physical meaning. We show that reasonable nonrelativistic quantum mechanics is exactly specified by the axioms. A system describing the electric Aharonov–Bohm effect is presented. It illustrates the topological obstructions for the existence of a Hamiltonian.
Multiple-oscillating-field techniques for accurate distance measurements by solid-state NMR
Authors: Straasø Lasse Arnt , Bjerring Morten , Khaneja Navin , Nielsen Niels Chr.
Published: June 2009

Dipolar truncation prevents accurate measurement of long-range internuclear distances between nuclei of the same spin species, e.g., within C13–C13 spin pairs in uniformly C13-isotope-labeled proteins, using magic-angle spinning solid-state NMR spectroscopy. Accordingly, one of the richest sources of accurate structure information is at present not exploited fully, leaving the bulk part of the experimentally derived structural constraints to less accurate long-range C13–C13 dipolar couplings estimated from methods based on spin diffusion through proton spins in the close environment. In this paper, we extend our previous triple-oscillating field technique [N. Khaneja and N. C. Nielsen, J. Chem. Phys. 128, 015103 (2008)] for dipolar recoupling without dipolar truncation in homonuclear spin systems to a more advanced rf modulation with four independent oscillations and rotations involving nonorthogonal axes. This provides important new degrees of freedom, which are used to improve the scaling factor of the recoupled dipole-dipole couplings by a factor of 2.5 relative to the triple-oscillating field approach. This significant improvement, obtained by refocusing of otherwise defocused parts of the residual dipolar coupling Hamiltonian, may be exploited to measure much weaker C13–C13 dipolar couplings (and thereby longer distances) with much higher accuracy. We present a detailed theoretical description of multiple-field oscillating recoupling experiments, along with numerical simulations and experimental results on U–C13, N15-L-threonine and U–C13,N15-ubiquitin.
Absolute stability mechanism of a swept cylinder laminar boundary layer with imposed spanwise periodic conditions
Authors: Piot E. , Casalis G.
Published: June 2009

The linear impulse response of a laminar three-dimensional boundary layer with imposed spanwise periodic conditions is theoretically analyzed. Because of the imposed spanwise periodicity, a unidirectional absolute instability is physically significant. The base flow is obtained through a direct numerical simulation of the flow along a swept cylinder, with periodic boundary conditions enforced at the spanwise boundaries. It is shown that this flow is absolutely stable. However, it exhibits crossflow modes of zero group velocity whose damping rate in time is quite slow. Moreover, these crossflow modes are spatially amplified. A direct numerical simulation of the same configuration but in the presence of surface roughness has enabled the observation of these traveling crossflow waves. The introduction of the roughness element in the computation creates initial transients that play the role of an impulselike forcing, which generates the traveling crossflow waves as predicted by the theoretical analysis. Depending on the roughness chordwise location, the frequency and damping rate in time of the crossflow waves change in agreement with the theoretical results.
Density functional theory study of multiply ionized weakly bound fullerene dimers
Authors: Zettergren Henning , Wang Yang , Lamsabhi Al Mokhtar , Alcamí Manuel , Martín Fernando
Published: June 2009

Multiply ionized fullerene dimers ([C60]2q+,q=1–6) have been studied by means of state-of-the-art density functional theory methods. We found that the singly charged dimer is more strongly bound than the corresponding neutral van der Waals dimer at the binding distance of the latter; in contrast, multiply charged dimers (q≥2) are unstable. For the latter dimers, the calculated kinetic energy release in the binary fission yielding intact fullerenes is lower than those reported in recent experimental work. This implies that, in such experiments, there are significant internal excitations in the separating monomers. We also show that electron transfer within the charged dimers occurs on the subfemtosecond time scale, in accordance with the high charge mobility observed in dimers and larger clusters of fullerenes. This provides an explanation for the even-odd effects in the measured multiple ionization yields of fullerene dimers.
Multilevel resistive switching with ionic and metallic filaments
Authors: Liu Ming , Abid Z. , Wang Wei , He Xiaoli , Liu Qi , Guan Weihua
Published: June 2009

The resistive random access memory (ReRAM) device with three distinguishable resistance states is fabricated by doping Cu into a portion of the ZrO2 oxide layer of the Ti/ZrO2/n+-Si structure. The temperature-dependent measurement results demonstrate that filaments due to ionic trap-controlled space charge limited current conduction and metallic bridge are formed at different voltages. The formation and rupture of these different conducting filamentary paths in parallel are suggested to be responsible for the multilevel switching with the large resistance ratio, which can be used to establish a reliable multilevel ReRAM solution with variation tolerance.
Photon drag effect in carbon nanotube yarns
Authors: Obraztsov Alexander N. , Lyashenko Dmitry A. , Fang Shaoli , Baughman Ray H. , Obraztsov Petr A. , Garnov Sergei V. , Svirko Yuri P.
Published: June 2009

We demonstrate that in graphitic nanocarbon materials, combination of ballistic conductivity and strong electron photon coupling opens a unique opportunity to observe transfer of momentum of the electromagnetic radiation to free carriers. The resulting drag of quasiballistically propagating electrons can be employed, in particular, to visualize the temporal profile, polarization, and propagation direction of the laser pulse. In this letter, we report the giant photon drag effect in yarns made of multiwall carbon nanotubes.
Ultrashort dead time of photon-counting InGaAs avalanche photodiodes
Authors: Dixon A. R. , Dynes J. F. , Yuan Z. L. , Sharpe A. W. , Bennett A. J. , Shields A. J.
Published: June 2009

We report a 1.036 GHz gated Geiger mode InGaAs avalanche photodiode with a detection dead time of just 1.93 ns. This is demonstrated by full recovery of the detection efficiency two gate cycles after a detection event, as well as a measured maximum detection rate of 497 MHz. As an application, we measure the second order correlation function g(2) of the emission from a diode laser with a single detector that works reliably at high speed owing to the extremely short dead time of the detector. The device is ideal for high bit rate fiber wavelength quantum key distribution and photonic quantum computing.
High efficiency organic photovoltaic cells based on a vapor deposited squaraine donor
Authors: Wang Siyi , Mayo Elizabeth I. , Perez M. Dolores , Griffe Laurent , Wei Guodan , Djurovich Peter I. , Forrest Stephen R. , Thompson Mark E.
Published: June 2009

2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ) is used as a donor material in vapor deposited organic heterojunction photovoltaic cells. Devices with the structure indium tin oxide/SQ (x)∕C60 (400Å)/bathocuproine (100Å)∕Al (1000Å), where x=65, 110, 150, and 200Å were compared. Devices with x=65Å exhibited a power conversion efficiency of 3.1% under 1sun, AM1.5G simulated solar irradiation, giving an open circuit voltage of 0.76±0.01V, a short circuit current of 7.01±0.05mA∕cm2, and a fill factor of 0.56±0.05. Thicker SQ films lead to lower short circuit currents and fill factors, giving conversion efficiencies in the range of 2.6% to 3.2%. The demonstration of sublimable SQ as a donor material opens up a family of compounds for use in small molecule based heterojunction photovoltaics.
The stabilities of boron nitride nanoribbons with different hydrogen-terminated edges
Authors: Ding Yi , Wang Yanli , Ni Jun
Published: June 2009

We have investigated the stabilities of boron nitride nanoribbons with different hydrogen-terminated edges by first principles calculations. Five kinds of the stable edges are determined for the zigzag boron nitride nanoribbons (ZBNNRs). While for the armchair boron nitride nanoribbons (ABNNRs), there are three kinds of the stable edges. ZBNNRs under hydrogen rich environment are found to be ferromagnetic metals, while ABNNRs are nonmagnetic semiconductors regardless of the hydrogen content.
Magnetocaloric properties of nanocrystalline La0.125Ca0.875MnO3
Authors: Biswas Anis , Samanta Tapas , Banerjee S. , Das I.
Published: June 2009

Some recent experimental studies show the invisibility of antiferromagnetic transition in the cases of manganites when their particle size is reduced to nanometer scale. In complete contrast to these cases, we have observed the signature of antiferromagnetic transition in the magnetocaloric properties of nanocrystalline La0.125Ca0.875MnO3 of average particle sizes 70 and 60 nm similar to its polycrystalline bulk form. The system exhibits inverse magnetocaloric effect in its polycrystalline and nanocrystalline forms. An extra ferromagnetic phase is stabilized at low temperature for the sample with particle size ∼60 nm.
Nonradiative energy transfer in ZnO nanorods/dye-doped polymer heterostructures
Authors: Park Jun Kue , Lee Kyu Won , Lee W. , Lee Cheol Eui
Published: June 2009

Nonradiative energy transfer from the ZnO nanorods (donor) to fluorescent dye-doped polymer (acceptor) was investigated in heterostructures of ZnO nanorods/dye-doped polymer films, with the fluorescent dye, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran, being doped into the host material, poly(9-vinylcarbazole). Introduction of the ZnO nanorods layer to the dye-doped polymer film devices turned out to give much enhanced and blueshifted photoluminescence.
Affinity-Based Proteomics Probes; Tools for Studying Carbohydrate-Processing Enzymes
Authors: Stubbs Keith A. , Vocadlo David J.
Published: June 2009

As more information becomes available through the efforts of high-throughput screens, there is increasing pressure on the three main ‘omic’ fields, genomics, proteomics, and metabolomics, to organize this material into useful libraries that enable further understanding of biological systems. Proteomics especially is faced with two highly challenging tasks. The first is assigning the activity of thousands of putative proteins, the existence of which has been suggested by genomics studies. The second is to serve as a link between genomics and metabolomics by demonstrating which enzymes play roles in specific metabolic pathways. Underscoring these challenges in one area are the thousands of putative carbohydrate-processing enzymes that have been bioinformatically identified, mostly in prokaryotes, but that have unknown or unverified activities. Using two brief examples, we illustrate how biochemical pathways within bacteria that involve carbohydrate-processing enzymes present interesting potential antimicrobial targets, offering a clear motivation for gaining a functional understanding of biological proteomes. One method for studying proteomes that has been developed recently is to use synthetic compounds termed activity-based proteomics probes. Activity-based proteomic profiling using such probes facilitates rapid identification of enzyme activities within proteomes and assignment of function to putative enzymes. Here we discuss the general design principles for these probes with particular reference to carbohydrate-processing enzymes and give an example of using such a probe for the profiling of a bacterial proteome.
An overview of Nitella (Characeae, Charophyceae) in Australia
Authors: Casanova Michelle T.
Published: June 2009

The genus Nitella Ag. in algal family Characeae is characterised by furcate (forked) branchlets, compressed oospores (i.e. oval in cross-section), terminal antheridia and a 10-celled coronula on the oogonium. Species of Nitella are submerged plants that grow in a variety of wetland and riverine habitats. Approximately 89 taxa of Nitella (species, subspecies, varieties and forms) have been described on the basis of Australian collections, and published estimates of the number of species range from 18 to >35. The lower value is based on the assumption that infra-specific variation is great, species have a wide distribution, monoecy and dioecy are not indicative of speciation and the number of furcations and the ratio of branchlet segment lengths vary for a species owing to the environment in which they grow. The higher value is based on evidence that morphological characters are relatively constant for a species, that oospore variation is a good indication of speciation and that monoecious and dioecious entities are not inter-fertile. An overview of Australian members of the genus is presented here as a framework for further taxonomic work. Representatives of all three subgenera of Nitella occur in Australia, with subgenus Nitella poorly represented, and subgenera Tieffallenia and Hyella equally speciose. The subgenera are defined here in relation to the Australian taxa they contain. In the present treatment, section Migularia is transferred from subgenus Tieffallenia to subgenus Hyella, and several species are transferred to subgenus Tieffallenia. Within subgenus Tieffallenia, variation in vegetative and oospore morphology is useful for distinguishing among sections and species. However, although members of subgenus Hyella display a similar range of variation in vegetative morphology, most of the species have similar, reticulate, oospore ornamentation. Australia is home to a large number of endemic species of Nitella, many of which are dioecious. The total number of species and the degree of endemism have been underestimated in earlier studies, and it is likely that more than 50 species of Nitella will be recognised on the basis of Australian specimens. A key to the subgenera, and keys to sections in the subgenera are provided.