bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioactive Molecules: Perfectly Shaped for Their Target?
Authors: Wirth Matthias , Sauer Wolfgang H. B.
Published: July 2011

In this study, we examined target subsets extracted from the MDL Drug Data Report (MDDR)1 to identify specific molecular shape profiles that are representative for compounds active on those targets. Normalized Principal Moments of Inertia Ratios (NPRs)2 have been used to describe molecular shape of small molecules in a finite triangular descriptor space. The clustering behavior of the MDDR target subsets in a cell‐based triangular system shows a significant difference compared to randomly sampled datasets and proves the capability of the NPR descriptor to provide information. For some of the target subsets, certain parts of the descriptor space are unlikely to be occupied by bioactive compounds. All analyzed datasets show a generally biased distribution of molecular shapes: the majority of their compounds exhibit a rod‐like character. The influence of the employed 3D conformer generators on this distribution has been assessed as well as the capability of multiple conformations of compounds to increase the shape space covered.
SketchSort: Fast All Pairs Similarity Search for Large Databases of Molecular Fingerprints
Authors: Tabei Yasuo , Tsuda Koji
Published: July 2011

Similarity networks of ligands are often reported useful in predicting chemical activities and target proteins. However, the naive method of computing all pairwise similarities of chemical fingerprints takes quadratic time, which is prohibitive for large scale databases with millions of ligands. We propose a fast all pairs similarity search method, called SketchSort, that maps chemical fingerprints to symbol strings with random projections, and finds similar strings by multiple masked sorting. Due to random projection, SketchSort misses a certain fraction of neighbors (i.e., false negatives). Nevertheless, the expected fraction of false negatives is theoretically derived and can be kept under a very small value. Experiments show that SketchSort is much faster than other similarity search methods and enables us to obtain a PubChem‐scale similarity network quickly.
Novel MRI detection of the ischemic penumbra: direct assessment of metabolic integrity
Authors: Holmes William M. , Lopez‐Gonzalez Maria R. , Gallagher Lindsay , Deuchar Graeme A. , Macrae I. Mhairi , Santosh Celestine
Published: July 2011

We describe a novel magnetic resonance imaging technique to directly assess the metabolic integrity of penumbral tissue following stroke. For ischemically stressed tissue to be salvageable, it has to be capable of recovering aerobic metabolism (in place of anaerobic metabolism) on reperfusion. We probed ischemic brain tissue by altering the rate of oxygen delivery using a challenge of 100% oxygen ventilation. Any change from anaerobic to aerobic metabolism should alter the rate of lactate production and hence, levels of tissue lactate. Stroke was induced by permanent middle cerebral artery occlusion in rats. In Series 1 (n = 6), changes in tissue lactate during and following 100% oxygen challenge were monitored using 1H magnetic resonance spectroscopy (MRS). Diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI) were used to locate MRS voxels within the ischemic core, the homotopic contralateral striatum and within PWI/DWI mismatch (i.e. presumed penumbra). After 20 min of oxygen, lactate signal change was −16.1 ± 8.8% (mean ± SD) in PWI/DWI mismatch, +2.8 ± 5.1% in the ischemic core, and −0.6 ± 7.6% in the contralateral striatum. Return to air ventilation for 20 min resulted in a reversal, with lactate increasing by 46 ± 25.3% in the PWI/DWI mismatch, 6.6 ± 6.2% in the ischemic core, and −5 ± 11.4% in the contralateral striatum. In Series 2 (n = 6), a novel form of spectroscopic imaging was used to acquire lactate change maps to spatially identify regions of lactate change within the ischemic brain. This technique has potential clinical utility by identifying tissue that displays anaerobic metabolism capable of recovering aerobic metabolism when oxygen delivery is increased, which could provide a more precise assessment of penumbra. Copyright © 2011 John Wiley & Sons, Ltd.
The Earliest Case of Spondylocarpotarsal Synostosis Syndrome (Roman Age—2nd Century ad)
Authors: Rubini M. , Cerroni V. , Zaio P.
Published: July 2011

Spondylocarpotarsal synostosis syndrome (SCT) is a rare genetic disease. It was described for the first time during the 1970s. The most relevant pathognomonic skeletal changes are vertebral malsegmentation and the fusion of the carpal and tarsal bones. This last implication can be absent in some cases. We have investigated a case of SCT in a female of about 40–45 years of age, dated to the 2nd century ad. This discovery is important for two reasons: first, SCT is not a recent disease but rather one with a very long history; second, the clinical picture of the skeletal changes (malsegmentation of some elements of the spine, fusion of carpal bones) seems not to have varied in the last 2000 years. Furthermore, the age of the Roman female shows medium–long survival in patients suffering from SCT, even in the absence of medical treatment. Copyright © 2011 John Wiley & Sons, Ltd.
Syntheses and optoelectronic properties of quinoxaline polymers: The effect of donor unit
Authors: Sendur Merve , Balan Abidin , Baran Derya , Toppare Levent
Published: July 2011

Tuning the bandgap of electrochromic polymers is one of the important research topics in electrochromism. To understand clearly the effect of donor unit in donor–acceptor–donor‐type polymers, 2,3‐bis(4‐tert‐butylphenyl)‐5,8‐di(thiophen‐2‐yl)quinoxaline and 2,3‐bis(4‐tert‐butylphenyl)‐5‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐ 5‐yl)‐8‐(thiophen‐2‐yl)quinoxaline were synthesized and polymerized potentiodynamically. Their electrochemical and spectroelectrochemical studies were performed, and the results were compared with those of poly(2,3‐bis(4‐tert‐butylphenyl)‐5,8‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)quinoxaline) (Gunbas et al., Adv Mater 2008, 20, 691–695). A blue shift in the polymer π–π* transitions revealed that the bandgap of such polymers with the same acceptor unit is related to the electron density of donor units. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of double‐hydrophilic block copolymers via combination of oxyanion‐initiated polymerization and polymer reaction for fabricating magnetic target gene carrier
Authors: Zhang Shihua , Gu Zixu , Hao Ying , Zhang Mingzu , Ni Peihong
Published: July 2011

In this work, we have synthesized a polycation and a polyanion via a combination of oxyanion‐initiated polymerization and polymer reaction, and then developed a novel approach to prepare a controlled magnetic target gene carrier with magnetic Fe3O4 nanoparticles as core and poly(ethylene glycol) (PEG) segment as corona via layer‐by‐layer (LbL) assembly and shell‐crosslinking. Magnetic nanoparticles (MNPs) were first modified by poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) via radical polymerization. The resulting MNPs were used to compact deoxyribonucleic acid (DNA) through LbL assembly, involving four steps: (1) the binding of DNA to the polycation PDMAEMA on the surface of MNPs; (2) the produced particles in Step 1 with negative charge interacting with additional polycation ethoxy group end‐capped PDMAEMA (EtO‐PDMAEMA) homopolymer, leading to a positive charge surface; (3) using carboxyl group (‐COO‐) of poly(methacrylic acid) (PMAA) in a diblock copolymer (MePEG2000‐b‐PMAASH) as polyanion, which has partial mercapto groups (‐SH) in PMAA segment, to interact with the particles produced in Step 2; (4) the shell of the composite nanoparticle was crosslinked by oxidizing the ‐SH groups of the MePEG2000‐b‐PMAASH to form disulfide linkage (SS). All the processes of LbL assembly were investigated by agarose gel retardation assay and zeta potential measurements. The in vitro cytotoxicity analysis proves that polyions/DNA MNPs have excellent properties and potential applications as gene carriers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Polyester from dimethylketene and acetaldehyde: Direct copolymerization and β‐lactone ring‐opening polymerization
Authors: Brestaz Marc , Desilles Nicolas , Le Guillaume , Bunel Claude
Published: July 2011

Two ways to obtain aliphatic polyesters (PEs) from dimethylketene and acetaldehyde were investigated. On the one hand, a direct anionic copolymerization was carried out in toluene at −60 °C. The resulting polymer was mainly composed of PE units. On the other hand, a two‐step process involving the synthesis of 3,3,4‐trimethyl‐2‐oxetanone by [2+2] cycloaddition, followed by its ring‐opening polymerization, with various initiators and solvents, led to the expected PE. Molecular weights up to 9000 g mol−1 (measured by nuclear magnetic resonance (NMR)), with narrow polydispersity around 1.2, were obtained. These polymers were found stable up to 274 °C under nitrogen and a broad and complex endothermic peak attributed to crystallinity was observed near 139 °C by differential scanning calorimetry (DSC). The crystallinity, measured by X‐ray diffraction, was close to 0.45. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Utilization of New Non‐toxic Substances as Stabilizers for Nitrocellulose‐Based Propellants
Authors: Fryš Ondřej , Bajerová Petra , Eisner Aleš , Skládal Jan , Ventura Karel
Published: July 2011

Propellants consisting of nitrocellulose (NC) and/or other nitrate esters are inherently chemically unstable and undergo decomposition even under standard storage conditions. Decomposition of such compounds can be inhibited or nearly stopped when stabilizers are used. However, conventional stabilizers form nitrosamines that have toxic and carcinogenic effects. As a result, these conventional stabilizers should be replaced as soon as possible.

A series of NC‐based propellants doped with different novel manufactured stabilizers were investigated using microcalorimetry, conventional stability tests, and sensitivity tests. The results were compared with propellants containing the conventional stabilizer Akardite II. The chemical structure of these new stabilizers and their decomposition products do not enable the formation of toxic N‐nitrosamines.
The advection–condensation model and water‐vapour probability density functions
Authors: Sukhatme Jai , Young William R.
Published: July 2011

The statistically steady humidity distribution resulting from an interaction of advection, modelled as an uncorrelated random walk of moist parcels on an isentropic surface, and a vapour sink, modelled as immediate condensation whenever the specific humidity exceeds a specified saturation humidity, is explored with theory and simulation. A source supplies moisture at the deep‐tropical southern boundary of the domain and the saturation humidity is specified as a monotonically decreasing function of distance from the boundary. The boundary source balances the interior condensation sink, so that a stationary spatially inhomogeneous humidity distribution emerges. An exact solution of the Fokker–Planck equation delivers a simple expression for the resulting probability density function (PDF) of the water‐vapour field and also the relative humidity. This solution agrees completely with a numerical simulation of the process, and the humidity PDF exhibits several features of interest, such as bimodality close to the source and unimodality further from the source. The PDFs of specific and relative humidity are broad and non‐Gaussian. The domain‐averaged relative humidity PDF is bimodal with distinct moist and dry peaks, a feature which we show agrees with middleworld isentropic PDFs derived from the ERA interim dataset. Copyright © 2011 Royal Meteorological Society
Avoiding bias in mixed model inference for fixed effects
Authors: Gurka Matthew J. , Edwards Lloyd J. , Muller Keith E.
Published: July 2011

Analysis of a large longitudinal study of children motivated our work. The results illustrate how accurate inference for fixed effects in a general linear mixed model depends on the covariance model selected for the data. Simulation studies have revealed biased inference for the fixed effects with an underspecified covariance structure, at least in small samples. One underspecification common for longitudinal data assumes a simple random intercept and conditional independence of the within‐subject errors (i.e., compound symmetry). We prove that the underspecification creates bias in both small and large samples, indicating that recruiting more participants will not alleviate inflation of the Type I error rate associated with fixed effect inference. Enumerations and simulations help quantify the bias and evaluate strategies for avoiding it. When practical, backwards selection of the covariance model, starting with an unstructured pattern, provides the best protection. Tutorial papers can guide the reader in minimizing the chances of falling into the often spurious software trap of nonconvergence. In some cases, the logic of the study design and the scientific context may support a structured pattern, such as an autoregressive structure. The sandwich estimator provides a valid alternative in sufficiently large samples. Authors reporting mixed‐model analyses should note possible biases in fixed effects inference because of the following: (i) the covariance model selection process; (ii) the specific covariance model chosen; or (iii) the test approximation. Copyright © 2011 John Wiley & Sons, Ltd.
Robust extraction of covariate information to improve estimation efficiency in randomized trials
Authors: Moore Kelly L. , Neugebauer Romain , Valappil Thamban , van der Laan Mark J.
Published: July 2011

In randomized trials, investigators typically rely upon an unadjusted estimate of the mean outcome within each treatment arm to draw causal inferences. Statisticians have underscored the gain in efficiency that can be achieved from covariate adjustment in randomized trials with a focus on problems involving linear models. Despite recent theoretical advances, there has been a reluctance to adjust for covariates based on two primary reasons: (i) covariate‐adjusted estimates based on conditional logistic regression models have been shown to be less precise and (ii) concern over the opportunity to manipulate the model selection process for covariate adjustments to obtain favorable results. In this paper, we address these two issues and summarize recent theoretical results on which is based a proposed general methodology for covariate adjustment under the framework of targeted maximum likelihood estimation in trials with two arms where the probability of treatment is 50%. The proposed methodology provides an estimate of the true causal parameter of interest representing the population‐level treatment effect. It is compared with the estimates based on conditional logistic modeling, which only provide estimates of subgroup‐level treatment effects rather than marginal (unconditional) treatment effects. We provide a clear criterion for determining whether a gain in efficiency can be achieved with covariate adjustment over the unadjusted method. We illustrate our strategy using a resampled clinical trial dataset from a placebo controlled phase 4 study. Results demonstrate that gains in efficiency can be achieved even with binary outcomes through covariate adjustment leading to increased statistical power. Copyright © 2011 John Wiley & Sons, Ltd.
Simulation study of power and sample size for repeated measures with multinomial outcomes: an application to sound direction identification experiments (SDIE)
Authors: Jiang Dingfeng , Oleson Jacob J.
Published: July 2011

This study focuses on sample size determination in repeated measures studies with multinomial outcomes from multiple factors. In settings where multiple factors have repeated measures, a single subject could have hundreds of observations. Sample size selection may then refer to the number of subjects, the number of levels within a factor, or the number of repetitions within the level. We simulate multinomial data through a generalized linear mixed model (GLMM) with and without overdispersion, compute the empirical power of detecting group difference for several analytical methods and contrast their performance in group comparison studies with repeated multinomial data. We use four spatial functions to model the spatial correlation structures among observations. We evaluate the factors affecting the power under various scenarios. We also present a dataset typical in hearing studies for sound localization, in which a spatially distributed array of audio loudspeakers plays multiple sounds in order to compare two programming schemes for a hearing aid device. Copyright © 2011 John Wiley & Sons, Ltd.
Cyanidin does not affect sulforaphane-mediated Nrf2 induction in cultured human keratinocytes
Authors: Ernst I. M. A. , Wagner A. E. , Huebbe P. , Rimbach G.
Published: July 2011

There is increasing interest in the gene-regulatory activities of isothiocyanates and flavonoids in human skin. Nrf2 agonists, such as isothiocyanate sulforaphane (SFN), have been shown to promote chemopreventive effects in skin both in vitro and in vivo. Recent data indicate that different secondary plant compounds may either antagonise or enhance SFN-induced Nrf2 activation. We therefore studied the interactions of a flavonoid, cyanidin and the potent Nrf2 inductor SFN in cultured human keratinocytes (HaCaT cells). We observed that cyanidin does not induce the activation of Nrf2 and its target genes, γ-glutamylcysteine synthetase (γGCS), NAD(P)H:quinone oxidoreductase 1 and haem oxygenase-1 in HaCaT cells. Furthermore, SFN-mediated Nrf2 activation and its target gene expression were not further enhanced by the co-application of SFN with cyanidin.
Potential applications of fish oils rich in n-3 fatty acids in the palliative treatment of advanced pancreatic cancer
Authors: Arshad Ali , Al-Leswas Dhya , Stephenson James , Metcalfe Matthew , Dennison Ashley
Published: July 2011

The palliative treatment of patients with advanced pancreatic cancer (APC) has undergone little advancement in the last 15 years. Novel therapies that have been investigated to extend survival have shown little benefit over existing chemotherapy regimens. Patients with APC often experience significant weight loss, which is one of the primary factors involved in declining quality of life. Recently, the ability of n-3 fatty acid rich oral preparations to attenuate or reverse tumour-related weight loss has been investigated in this patient group with encouraging results. Laboratory investigation has also yielded promising results suggesting a potential direct tumouricidal effect of n-3 fatty acids as well as the putative potentiation of existing chemotherapy regimes. The present review aims to examine the potential applications of fish oils rich in n-3 fatty acids in patients with APC, present a selection of the studies carried out to date and outline avenues of possible further clinical investigation.
Sequence variability in two mitochondrial DNA regions and internal transcribed spacer among three cestodes infecting animals and humans from China
Authors: Dai R.S. , Liu G.H. , Song H.Q. , Lin R.Q. , Yuan Z.G. , Li M.W. , Huang S.Y. , Liu W. , Zhu X.Q.
Published: July 2011

Sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochromecoxidase subunit 1 (cox1) and NADH dehydrogenase subunit 4 (nad4), and internal transcribed spacer (ITS) of rDNA among and within three cestodes,Spirometra erinaceieuropaei,Taenia multicepsandTaenia hydatigena, from different geographical origins in China was examined. A portion of thecox1 (pcox1),nad4 genes (pnad4) and the ITS (ITS1+5.8S rDNA+ITS2) were amplified separately from individual cestodes by polymerase chain reaction (PCR). Representative amplicons were subjected to sequencing in order to estimate sequence variability. While the intra-specific sequence variations within each of the tapeworm species were 0–0.7% for pcox1, 0–1.7% for pnad4 and 0.1–3.6% for ITS, the inter-specific sequence differences were significantly higher, being 12.1–17.6%, 18.7–26.2% and 31–75.5% for pcox1, pnad4 and ITS, respectively. Phylogenetic analyses based on the pcox1 sequence data revealed thatT. multicepsandT. hydatigenawere more closely related to the other members of theTaeniagenus, andS. erinaceieuropaeiwas more closely related to the other members of theSpirometragenus. These findings demonstrated clearly the usefulness of mtDNA and rDNA sequences for population genetic studies of these cestodes of socio-economic importance.
Bismuth iodoform paraffin paste: a review
Authors: Crossland G J , Bath A P
Published: July 2011

Introduction:

This article reviews the literature pertaining to bismuth iodoform paraffin paste.

Overview:

Bismuth iodoform paraffin paste is used in most otolaryngology departments on a daily basis. Questions about its properties are common in postgraduate otolaryngology examinations. This article reviews bismuth iodoform paraffin paste's current and historical usage, constituents, properties, side effects, and radiographic properties, and its alternatives in otological and rhinological practice.
An unfortunate case of Pendred syndrome
Authors: Sanei-Moghaddam A , Wilson T , Kumar S , Gray R
Published: July 2011

Objective:

To report a patient with Pendred syndrome who developed life-threatening hypokalaemia as an unpredicted consequence of implant-induced imbalance and alcohol dependency, leading to multiple cardiac arrests.

Setting:

Addenbrooke's Hospital, Cambridge, UK.

Method:

Case report and review of the English language literature concerning Pendred syndrome and cochlear implantation in Pendred syndrome patients.

Result:

Pendred syndrome is an autosomal recessive disorder which mainly affects the inner ear, thyroid and kidneys. It accounts for 10 per cent of syndromic hearing loss cases. The majority of Pendred syndrome patients are referred to cochlear implant programmes for hearing assessment and therapy. They may also have an underlying metabolic abnormality which is not clinically apparent.

Conclusion:

Providing cochlear implants to patients with Pendred syndrome demands extensive knowledge of this condition, in order to avoid potential morbidity.
Malleo-incudal osteoma: an unexpected finding during surgery for presumed otosclerosis
Authors: Ramdoo K , Dale O T , Herdman R C D
Published: July 2011

Objective:

To report a rare case of a symptomatic malleo-incudal osteoma, and to highlight the difficulties in making the clinical diagnosis.

Method:

Case report and literature review.

Results:

Malleo-incudal osteoma is a rare cause of unilateral conductive hearing loss. Its symptoms may mimic those of other otological causes of conductive hearing loss, such as otosclerosis.

Conclusion:

This case report highlights the challenges involved in establishing a clinical diagnosis of malleo-incudal osteoma. It also emphasises the importance of assessing the mobility of the divided ossicular chain during a planned stapedectomy.
Response to Martin Ball & Joan Rahilly, ‘The symbolization of central approximants in the IPA’,JIPA41 (2011), 231–237
Authors: Recasens Daniel
Published: July 2011

In the paper ‘The symbolization of central approximants in the IPA’, Martin Ball and Joan Rahilly approach an interesting problem – the phonetic transcription of approximants other than the so-called semivowels. In the absence of special symbols in the IPA chart, they suggest that special characters should be used for the notation of approximant realizations made at the bilabial, dental, alveolar, lamino-postalveolar, palatal, velar, uvular and pharyngeal places of articulation. In their view, the introduction of new symbols should render those sounds comparable to other non-semivowel approximants for which special symbols are available, i.e., [ʋ] (labiodental), [ɹ] (apico-postalveolar) and [ɻ] (retroflex), while, at the same time, avoiding having to add the lowered diacritic to the voiced fricative symbols [β ðzʒ ʁ ʕ].
Intonational convergence in language contact: Utterance-final F0 contours in Catalan–Spanish early bilinguals
Authors: Simonet Miquel
Published: July 2011

This study investigates utterance-final pitch accents in declaratives in two contact languages (Catalan and Spanish) as produced by two groups of Catalan–Spanish bilinguals (Catalan-dominant and Spanish-dominant). It contributes to a growing body of research showing that bilinguals transfer the intonational patterns of their native language to their non-native language, and it provides a sociolinguistic profile of an intonational variable in a language contact situation. We also examine the interaction of native and non-native patterns within the performance of the bilinguals. Evidence is presented for the existence of a process of phonetic category assimilation of non-native pitch contrasts to native pitch contours, as well as for phonetic new-category formation in second language learning.
Robert Falcon Scott: a Tasmanian connection
Authors: Quilty Patrick G. , Winter Gillian
Published: July 2011

The Edge Anglican church (originally St Alban's) in the northern Hobart suburb of Claremont has above its main altar a triptych stained glass window, a memorial to Robert Falcon Scott R.N. New information suggests that the designer/manufacturer was Auguste Fischer of Melbourne, a close associate of the church's architect, Alan Cameron Walker of Hobart. The window was promised by Mrs Edith Knight at the laying of the foundation stone of the church in July 1913, five months after Scott's death became known to the world. Lady Ellison-Macartney attended the ceremony. She was Scott's sister and wife of the recently appointed governor of Tasmania, Sir William Ellison-Macartney. Other members of Scott's family were also living in Hobart at the time. The Ellison-Macartneys and their daughter Esther attended the dedication of the window on 17 October 1915. Admiral E.R.G.R. Evans, second in command of Scott's expedition, spoke to The Royal Society of Tasmania on 29 March 1930, on the topic of Scott's last Antarctic venture.
Conceptualizing Age-Friendly Communities
Authors: Menec Verena H. , Means Robin , Keating Norah , Parkhurst Graham , Eales Jacquie
Published: July 2011

Sur le front politique et des lignes de conduite, l’intérêt a augmenté pour rendre les communautés plus « amies des ainés », cette tendance est restée constante depuis que l’Organisation mondiale de la Santé a lancé son projet « Réseau mondial des Villes-amies des aînés. » Nous conceptualisons les communautés amies des aînés en nous appuyons sur le cadre de l’OMS et l’application d’un point de vue écologique. Ainsi nous visons à rendre explicite les principales hypothèses sur l’interaction entre la personne et l’environnement afin de faire progresser la recherche ou de décisions politiques dans ce domaine. Les prémisses écologiques (par exemple, il doit y avoir une adéquation entre la personne âgée et les conditions environnementales) suggèrent la nécessité d’une approche de recherche holistique et interdisciplinaire. Une telle approche est requise car les domaines amis des aînés (l’environnement physique, le logement, l’environnement social, les possibilités de participation, le soutien communautaire formel et informel et les services de santé, de transport, de communication et de l’information) ne peuvent pas être traitées independamment des facteurs personnels, tels que l’âge, le sexe, le revenu et l’état fonctionnel, ainsi que des autres niveaux d’influence, y compris l’environnement politique.
Differential expression of Axin1, Cdc25c and Cdkn2d mRNA in 2-cell stage mouse blastomeres
Authors: Sun Jian Hong , Zhang Yong , Yin Bao Ying , Li Ji Xia , Liu Gen Sheng , Xu Wei , Tang Shuang
Published: July 2011

There is increasing evidence to show that 2-cell stage mouse blastomeres have differing developmental properties. Additionally, it has been suggested that such a difference might be due to their distribution of mRNA and/or protein asymmetry. However, to date, the exact genes that are involved in the orientation and order of blastomere division are not known. In this study, some differentially expressed transcripts were identified. Axin1, cell division cycle 25 homolog C (Cdc25c) and cyclin-dependent inhibitor 2D (Cdkn2d) were selected for validation by real-time polymerase chain reaction (PCR) based on published data. Our real-time PCR results demonstrated thatAxin1,Cdc25candCdkn2dgenes had different levels of expression among blastomeres of the mouse 2-cell embryo i.e. the level of Axin1 mRNA was significantly higher in one blastomere when compared with the other blastomeres of the 2-cell embryo (p< 0.05). The variation in Cdc25c (p< 0.05) and Cdkn2d (p< 0.01) mRNA expression followed a similar trend to that of Axin1. In addition, the highest levels of expression of these three genes were detected in the same blastomere in the 2-cell embryo. We confirmed that there was an asymmetrical distribution pattern for Axin1, Cdc25c and Cdkn2d transcripts in 2-cell embryos. In conclusion, this study demonstrated clearly that there is embryonic asymmetry at the 2-cell stage and that these differentially expressed genes may result in differentiation in expression in embryo development.
Testing models of rotating stars
Authors: Potter Adrian T. , Tout Christopher A.
Published: July 2011

The effects of rapid rotation on stellar evolution can be profound but we are only now starting to gather the data necessary to adequately determine the validity of the many proposed models of rotating stars. Some aspects of stellar rotation, particularly the treatment of angular momentum transport within convective zones, still remain very poorly explored. Distinguishing between different models is made difficult by the typically large number of free parameters in models compared with the amount of available data. This also makes it difficult to determine whether increasing the complexity of a model actually results in a better reflection of reality. We present a new code to straightforwardly compare different rotating stellar models using otherwise identical input physics. We use it to compare several models with different treatments for the transport of angular momentum within convective zones.
Results from a recent stellar rotation census of B stars
Authors: Huang Wenjin , Gies Douglas R. , McSwain M. Virginia
Published: July 2011

In an analysis of the rotational properties of more than 1100 B stars (~660 cluster and ~500 field B stars), we determine the projected rotational velocity (V sin i), effective temperature, gravity, mass, and critical rotation speed for each star. The new data provide us a solid observational base to explore many hot topics in this area: Why do field B stars rotate slower than cluster B stars? How fast do B stars rotate when they are just born? How fast can B stars rotate before they become Be stars? How does the rotation rate of B stars change with time? Does the evolutionary change in rotation velocity lead to the Be phenomenon? Here we report the results of our efforts in searching for answers to these questions based on the latest B star census.
Mass and angular momentum loss of fast rotating stars via decretion disks
Authors: Krtička Jiří , Owocki Stan P. , Meynet Georges
Published: July 2011

The spinup of massive stars induced by evolution of the stellar interior can bring the star to near-critical rotation. In critically rotating stars the decrease of the stellar moment of inertia must be balanced by a net loss of angular momentum through an equatorial decretion disk. We examine the nature and role of mass loss via such disks. In contrast to the usual stellar wind mass loss set by exterior driving from the stellar luminosity, such decretion-disk mass loss stems from the angular momentum loss needed to keep the star near and below critical rotation, given the interior evolution and decline in the star's moment of inertia. Because the specific angular momentum in a Keplerian disk increases with the square root of the radius, the decretion mass loss associated with a required level of angular momentum loss critically depends on the outer radius for viscous coupling of the disk, and can be significantly less than the spherical, wind-like mass loss commonly assumed in evolutionary calculations.
Evolutionary effects of stellar rotation of massive stars in their pre-supernova environments
Authors: Pérez-Rendón Brenda , Pineda-León Horacio , Santillán Alfredo , Hernández-Cervantes Liliana
Published: July 2011

Massive main sequence stars are fast rotators. Stellar rotation affects massive stellar rotation due to rotationally induced mixing processes, the increase of mass loss rates, etc. and also affects the circumstellar medium due to their interaction with the stellar wind. The parameters of stellar winds depends on stellar parameters so the wind parameters change as the star evolves, coupling the evolution of circumstellar medium to the star itself. In this work we used a stellar code to build models of two massive stars (30 and 40 M⊙) and we used their wind parameters to simulate the hydrodynamics of their surrounding gas with the ZEUS-3D code in order to explore the effects of stellar rotation in the pre-supernova environments.
The Nitrogen Abundance in Be Stars Determined from UV Spectra
Authors: Peters Geraldine J.
Published: July 2011

A NLTE abundance analysis of the IUE spectra of 8 Be stars with v sin i < 150km s−1 reveals no evidence for nitrogen enrichment from mixing of core and photospheric material.
Modeling the winds and magnetospheres of active OB stars
Authors: Townsend Richard H. D.
Published: July 2011

After briefly reviewing the theory behind the radiative line-driven winds of OB stars, I examine the processes that can generate structure in them; these include both intrinsic instabilities, and surface perturbations such as pulsation and rotation. I then delve into wind channeling and confinement by magnetic fields as a mechanism for forming longer-lived circumstellar structures. With a narrative that largely follows the historical progression of the field, I introduce the key insights and results that link the first detection of a magnetosphere, over three decades ago, to the recent direct measurement of magnetic braking in a number of active OB stars.
Searching for massive star magnetospheres
Authors: Bohlender David , Monin Dmitry
Published: July 2011

We review the status of a long-term program to search for stellar magnetospheres in Bp stars. A few new σOri E analogues discovered during the course of this investigation are briefly discussed and other stars that may be worthy of further study are noted.
The constant magnetic field of ξ1 CMa: geometry or slow rotation?
Authors: Fourtune-Ravard Chloé , Wade Gregg A. , Marcolino Wagner L. F. , Shultz Matthew , Grunhut Jason H. , Henrichs Huib F. ,   the MiMeS Collaboration
Published: July 2011

We report recent observations of the sharp-lined magnetic βCep pulsator ξ1 CMa (= HD 46328). The longitudinal magnetic field of this star is detected consistently, but it is not observed to vary significantly, during nearly 5 years of observation. In this poster we evaluate whether the constant longitudinal field is due to intrinsically slow rotation, or rather if the stellar or magnetic geometry is responsible.
Is the wind of the Oe star HD 155806 magnetically confined?
Authors: Fullerton Alex W. , Petit Véronique , Bagnulo Stefano , Wade Gregg A. ,   the MiMeS Collaboration
Published: July 2011

Spectropolarimetric observations of HD 155806 – the hottest Galactic Oe star – were obtained with CFHT/ESPaDOnS to test the hypothesis that disk signatures in its spectrum are due to magnetic channeling and confinement of its stellar wind. We did not detect a dipole field of sufficient strength to confine the wind, and could not confirm previous reports of a magnetic detection. It appears that stellar magnetism is not responsible for producing the disk of HD 155806.
Searching for magnetic fields in the descendants of massive OB stars
Authors: Grunhut Jason H. , Wade Gregg A. , Hanes David A. , Alecian Evelyne
Published: July 2011

We present the results of a recent survey of cool, late-type supergiants - the descendants of massive O- and B-type stars - that has systematically detected magnetic fields in these stars using spectropolarimetric observations obtained with ESPaDOnS at the Canada-France-Hawaii Telescope. Our observations reveal detectable, often complex, Stokes V Zeeman signatures in Least-Squares Deconvolved mean line profiles in a significant fraction of the observed sample of ~30 stars.
A MiMeS analysis of the magnetic field and circumstellar environment of the weak-wind O9 sub-giant star HD 57682
Authors: Grunhut Jason H. , Wade Gregg A. , Marcolino Wagner L. F. , Petit Véronique ,   the MiMeS Collaboration
Published: July 2011

I will review our recent analysis of the magnetic properties of the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the Canada-France-Hawaii telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Program. I discuss our most recent determination of the rotational period from longitudinal magnetic field measurements and Hα variability - the latter obtained from over a decade's worth of professional and amateur spectroscopic observations. Lastly, I will report on our investigation of the magnetic field geometry and the effects of the field on the circumstellar environment.
The magnetic field of the B1/B2V star σ Lup
Authors: Henrichs Huib F. , Kolenberg Katrien , Plaggenborg Benjamin , Marsden Stephen C. , Waite Ian A. , Wade Gregg A. ,   the MiMeS collaboration
Published: July 2011

The ultraviolet stellar wind lines of the photometrically periodic variable early B-type star σ Lupi were found to behave very similarly to what has been observed in known magnetic B stars, although no periodicity could be determined. AAT spectropolarimetric measurements with SEMPOL were obtained. We detected a longitudinal magnetic field with varying strength and amplitude of about 100 G with error bars of typically 20 G. This type of variability supports an oblique magnetic rotator model. We fold the equivalent width of the 4 usable UV spectra in phase with the well-known photometric period of 3.019 days, which we identify with the rotation period of the star. The magnetic field variations are consistent with this period. Additional observations with ESPaDOnS attached to the CFHT strongly confirmed this discovery, and allowed to determine a precise magnetic period. Like in the other magnetic B stars the wind emission likely originates in the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.0182 d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field. No helium or other chemical peculiarity is known for this object.
Searching for weak or complex magnetic fields in polarized spectra of Rigel
Authors: Shultz Matthew , Wade Gregg A. , Neiner Coralie , Manset Nadine , Petit Véronique , Grunhut Jason H. , Guinan Edward , Hanes David A. ,   the MiMeS collaboration
Published: July 2011

Seventy-eight high-resolution Stokes V, Q and U spectra of the B8Iae supergiant Rigel were obtained with the ESPaDOnS spectropolarimeter at CFHT and its clone NARVAL at TBL in the context of the Magnetism in Massive Stars (MiMeS) Large Program, in order to scrutinize this core-collapse supernova progenitor for evidence of weak and/or complex magnetic fields. In this paper we describe the reduction and analysis of the data, the constraints obtained on any photospheric magnetic field, and the variability of photospheric and wind lines.
Line profiles of OB star winds using a Monte Carlo method
Authors: Šurlan Brankica , Kubát Jiří
Published: July 2011

The solution of the radiative transfer in an expanding atmospheres using the Monte Carlo method is presented. We applied our method to winds of several OB stars. In our calculation, the velocity and density structure is assumed to be given. Selected line profiles are shown.
Influence of decoupling effect on stellar wind variability
Authors: Votruba Viktor , Šejnová Klára , Koubský Pavel , Korčáková Daniela
Published: July 2011

A detailed investigation of momentum transfer in radiatively driven stellar winds shows that for the thin wind case ion decoupling may occur. The decoupling of absorbing ions significantly affects dynamics of the wind. We analysed such effects using our hydrodynamic code and predicted spectral changes with the help of the SHELLSPEC code.
Magnetic fields in classical Be stars: results of our long-term program with FORS1 at the VLT
Authors: Yudin Ruslan V. , Hubrig Swetlana , Pogodin Michail A. , Schoeller Markus
Published: July 2011

We report the results of our search for magnetic fields in a representative sample of classical Be stars carried out during 2006-2008 using low-resolution spectropolarimetry with FORS1 at the VLT. Among the 28 classical Be stars studied, detections of a magnetic field were achieved in seven stars (i.e. ~25%). The detected magnetic fields are rather weak, not stronger than ~150G. Among the Be stars studied with time series, one Be star, λ Eri, displays cyclic variability of the magnetic field with a period of 21.12 min.
ArasBeam: when amateurs contribute to Be star research
Authors: Cochard François , Desnoux Valérie , Buil Christian
Published: July 2011

Since 2003, the amateur astronomical community has decided, in collaboration with the Paris-Meudon Observatory, to coordinate their observations to get the best spectral survey of Be stars as possible. A database for amateur and professional Be star spectra, BeSS, has been created. Spectrographs (up to R=20000) and software tools have been developed for amateurs. Among them, ArasBeam is a web-based tool designed to organize amateur Be spectral observations. A very simple color coding indicates to any observer which stars must be observed on the following night to get the best possible survey of Be stars. So far, more than 11000 amateur spectra have been collected in BeSS. About all bright Be stars (up to magnitude 8) listed in BeSS and visible from the Northern hemisphere have been observed at least one time. In addition, 6 outbursts have been detected by amateurs in the last 2 years.
Spectrographs for small telescopes
Authors: Thizy Olivier , Cochard François
Published: July 2011

Shelyak Instruments is a company founded in 2006 offering a full range of spectrographs designed for Astronomy, shipping World Wide. Current users are (1) Public and private observatories who want to setup small telescope for scientific programs or training; (2) Universities for education and demonstrations; (3) Experienced amateurs observers who work in Pro/Amateur collaborations. Lhires III Littrow high resolution spectrograph and eShel optical fibre fed echelle solution are presented with some scientific results including OB stars in which those instruments had a significant contribution.
BeSS, the official Be Star Spectra database
Authors: de Batz Bertrand , Neiner Coralie , Floquet Michèle , Cochard François
Published: July 2011

We present the status of the BeSS database, which contains a catalogue of all known classical Be stars and a large collection of their spectra obtained at any wavelength, any epoch, and from various sources, from amateur astronomer spectra to professional high-resolution high signal-to-noise echelle spectra. Efficient data retrieval in such a heterogeneous data collection is possible with a wide range of selection criteria thanks to their storage in the fits format and via a web interface (http://basebe.obspm.fr) as well as via the Virtual Observatory. BeSS already contains over 49000 spectra and has allowed the detection of several outbursts.
Statistical search for Be stars candidates in the Small Magellanic Cloud
Authors: García-Varela Alejandro , Sabogal Beatriz , Mennickent Ronald E.
Published: July 2011

A report of a systematic search for Be star candidates in the Small Magellanic Cloud using statistical selection criteria is presented. The results are compared with those obtained with a standard photometric method to search for Be star candidates.
A statistical study of galactic bright Be stars
Authors: Miroshnichenko Anatoly S.
Published: July 2011

Creation of a modern database with a wide variety of data is an important step toward a better understanding of the Be phenomenon. In an effort to do that, I refined the existing catalog of Galactic Be stars and collected available observational data for 340 brightest objects and present some results of these data analysis. New candidates for Be binaries, which seem to represent a large fraction of Be stars, are suggested. Importance of the circumstellar optical continuum for modeling of the Be star envelopes is illustrated.
The e-MERLIN Cyg OB2 radio survey (COBRaS)
Authors: Prinja Raman K. , Fenech Danielle
Published: July 2011

The e-MERLIN Cyg OB2 Radio Survey (COBRaS) is designed to exploit e-MERLIN's enhanced capabilities to conduct uniquely probing, targeted deep-field mapping of the massive Cyg OB2 association in our Galaxy. The project aims to deliver (between 2010 to 2013) the most detailed radio census for the most massive OB association in the northern hemisphere, offering direct comparison to not only massive clusters in general, but also young globular clusters and super star clusters. With the COBRaS Legacy project we will assemble a uniform dataset of lasting value that is critical for advancing our understanding of current astrophysical problems in the inter-related core themes of (i) mass loss and evolution of massive stars, (ii) the formation, dynamics and content of massive OB associations, and (iii) the frequency of massive binaries and the incidence of non-thermal radiation.
Spatially resolving the wind and disk structures around active B-type stars
Authors: Tycner Christopher
Published: July 2011

Long-baseline optical and IR interferometers now routinely resolve the wind and disk-like structures around early-type stars. The typical angular scales resolved by current generation of instruments are well bellow the milli-arcsecond level. These type of observations allow, in some cases for the first time, placing very tight constraints on current theories and models of the circumstellar structures around these type of stars. Specific examples of observations obtained at the Navy Prototype Optical interferometer of the spatially resolved regions around a luminous blue variable star P Cyg and a B-type star with circumstellar disk are presented. The need for connection between interferometric observables and physical parameters predicted by theory and numerical models are emphasized.
High spatial resolution monitoring of the activity of BA supergiant winds
Authors: Chesneau Olivier , Dessart Luc , Kaufer Andreas , Mourard Denis , Stahl Otmar , Prinja Raman K. , Owocki Stan P.
Published: July 2011

There are currently two optical interferometry recombiners that can provide spectral resolutions better than 10000, AMBER/VLTI operating in the H-K bands, and VEGA/CHARA, recently commissioned, operating in the visible. These instruments are well suited to study the wind activity of the brightest AB supergiants in our vicinity, in lines such as Hα or Brγ. We present here the first observations of this kind, performed on Rigel (B8Ia) and Deneb (A2Ia). Rigel was monitored by AMBER in two campaigns, in 2006-2007 and 2009-2010, and observed in 2009 by VEGA; whereas Deneb was monitored in 2008-2009 by VEGA. The extension of the Hα and Brγ line forming regions were accurately measured and compared with CMFGEN models of both stars. Moreover, clear signs of activity were observed in the differential visibility and phases. These pioneer observations are still limited, but show the path for a better understanding of the spatial structure and temporal evolution of localized ejections using optical interferometry.