5,461 research outputs found

    Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations

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    Until recently, determining the rotational properties of galaxies in the early universe (z>4, Universe age <1.5Gyr) was impractical, with the exception of a few strongly lensed systems. Combining the high resolution and sensitivity of ALMA at (sub-) millimeter wavelengths with the typically high strength of the [CII] 158um emission line from galaxies and long-developed dynamical modeling tools raises the possibility of characterizing the gas dynamics in both extreme starburst galaxies and normal star forming disk galaxies at z~4-7. Using a procedure centered around GIPSY's ROTCUR task, we have fit tilted ring models to some of the best available ALMA [CII] data of a small set of galaxies: the MS galaxies HZ9 & HZ10, the Damped Lyman-alpha Absorber (DLA) host galaxy ALMA J0817+1351, the submm galaxies AzTEC/C159 and COSMOS J1000+0234, and the quasar host galaxy ULAS J1319+0950. This procedure directly derives rotation curves and dynamical masses as functions of radius for each object. In one case, we present evidence for a dark matter halo of O(10^11) solar masses. We present an analysis of the possible velocity dispersions of AzTEC/C159 and ULAS J1319+0950 based on matching simulated observations to the integrated [CII] line profiles. Finally, we test the effects of observation resolution and sensitivity on our results. While the conclusions remain limited at the resolution and signal-to-noise ratios of these observations, the results demonstrate the viability of the modeling tools at high redshift, and the exciting potential for detailed dynamical analysis of the earliest galaxies, as ALMA achieves full observational capabilities.Comment: 20 pages, 6 figures, Accepted for publication in Ap

    Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

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    In this investigation, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to study the evolution of deformation in Al13Co4. Streaking of the Laue spots showed that the onset of plastic flow occured at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enabled the geometrically necessary dislocation density to be estimated as 1.1 x 1013 m-2

    The Magnificent Seven: Magnetic fields and surface temperature distributions

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    Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name ``The Magnificent Seven''. Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which are interpreted as cyclotron resonance absorption lines by protons or heavy ions and / or atomic transitions shifted to X-ray energies by strong magnetic fields of the order of 10^13 G. New XMM-Newton observations indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals variations in derived emission temperature and absorption line depth with pulse phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are interpreted as due to free precession of the neutron star. Modeling of the pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the surface temperature distribution of the neutron stars indicating hot polar caps which have different temperatures, different sizes and are probably not located in antipodal positions.Comment: 10 pages, 8 figures, to appear in Astrophysics and Space Science, in the proceedings of "Isolated Neutron Stars: from the Interior to the Surface", edited by D. Page, R. Turolla and S. Zan

    Switzerland-wide Neospora caninum seroprevalence in female cattle and identification of risk factors for infection.

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    INTRODUCTION Neospora caninum is an important cause of abortion in cattle worldwide. Infection in cattle occurs horizontally by ingestion of oocysts shed by canids or vertically, from an infected dam to the fetus, and may result in abortion, stillbirth, or birth of seropositive offspring. The control of bovine neosporosis is difficult and costly. The objectives of this study were to estimate the current nationwide seroprevalence of N. caninum infections in Swiss cattle and to assess risk factors for infection with this parasite. METHODS We conducted a cross-sectional study with cattle farms randomly selected and stratified according to population size, resulting in a sample of 780 female cattle. The cattle originated from 161 farms distributed over all Switzerland. The serum samples were tested for antibodies against N. caninum using a commercial ELISA and if inconclusive, retested using an in-house immunoblot technique. To collect farm parameters relevant to N. caninum transmission and prevention, farm owners were mailed a questionnaire which addressed topics putatively related to N. caninum infection such as husbandry, history of abortion, and presence of dogs on farm. Univariate analysis by generalized linear mixed model (with animal seropositivity as outcome variable) and logistic regression modeling (with farm seropositivity as outcome variable) was conducted on farm parameters investigated in the questionnaire. RESULTS By ELISA and immunoblot, 4.2% (33/780) of cattle sera yielded positive results. At the farm level, 16.2% (26/161) of the sampled farms had at least one seropositive animal. The return rate of the valid questionnaires was 54.0%. At the animal level, odds for farm seropositivity were 3.8 times higher when rodents had been recorded by the farmer as a problem on the farm. At the farm-level, two protective factors were identified: rearing of replacement heifers and feeding of concentrated feed. CONCLUSION We recorded a low seroprevalence of N. caninum in a random sample of Swiss cattle representative for the years 2017-2018. Based on a questionnaire survey, we could identify risk and protective factors for infection with N. caninum, however their biological relevance needs to be confirmed in further studies

    Suggested Improvements in the Law of Evidence

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    The Washington Committee on Judicial Administration assigned a section of its membership to study the law of evidence in the state of Washington in the light of the Reports of the Section of Judicial Administration of the American Bar Association, published in July, 1938. The observations and recommendations of the Washington Section on the Law of Evidence appear in the following report

    Clinical and MRI responses to etanercept in early non-radiographic axial spondyloarthritis : 48-week results from the EMBARK study

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    Objective: To evaluate the efficacy and safety of etanercept (ETN) after 48 weeks in patients with early active non-radiographic axial spondyloarthritis (nr-axSpA). Methods: Patients meeting Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA, but not modified New York radiographic criteria, received double-blind ETN 50 mg/week or placebo (PBO) for 12 weeks, then open-label ETN (ETN/ETN or PBO/ETN). Clinical, health, productivity, MRI and safety outcomes were assessed and the 48-week data are presented here. Results: 208/225 patients (92%) entered the open-label phase at week 12 (ETN, n=102; PBO, n=106). The percentage of patients achieving ASAS40 increased from 33% to 52% between weeks 12 and 48 for ETN/ETN and from 15% to 53% for PBO/ETN (within-group p value <0.001 for both). For ETN/ETN and PBO/ETN, the EuroQol 5 Dimensions utility score improved by 0.14 and 0.08, respectively, between baseline and week 12 and by 0.23 and 0.22 between baseline and week 48. Between weeks 12 and 48, MRI Spondyloarthritis Research Consortium of Canada sacroiliac joint (SIJ) scores decreased by -1.1 for ETN/ETN and by -3.0 for PBO/ETN, p<0.001 for both. Decreases in MRI SIJ inflammation and C-reactive protein correlated with several clinical outcomes at weeks 12 and 48. Conclusions: Patients with early active nr-axSpA demonstrated improvement from week 12 in clinical, health, productivity and MRI outcomes that was sustained to 48 weeks

    Highly flexible silica/chitosan hybrid scaffolds with oriented pores for tissue regeneration

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    Inorganic/organic sol–gel hybrids have nanoscale co-networks of organic and inorganic components that give them the unique potential of tailored mechanical properties and controlled biodegradation in tissue engineering applications. Here, silica/chitosan hybrid scaffolds with oriented structures were fabricated through the sol–gel method with a unidirectional freeze casting process. 3-Glycidoxypropyl trimethoxysilane (GPTMS) was used to obtain covalent inorganic/organic coupling. Process variables were investigated such as cooling rate, GPTMS and inorganic content, which can be used to tailor the mechanical properties and hybrid chemical coupling. Structural characterization and dissolution tests confirmed the covalent cross-linking of the chitosan and the silica network in hybrids. The scaffolds had a directional lamellar structure along the freezing direction and a cellular morphology perpendicular to the freezing direction. Compression testing showed that the scaffolds with 60 wt% organic were flexible and elastomeric perpendicular to the freezing direction whilst behaving in an elastic-brittle fashion parallel to the freezing direction. The compressive strengths are about one order of magnitude higher in the latter direction reaching values of the order of 160 kPa. This behaviour provides potential for clinicians to be able to squeeze the materials to fit tissue defect sites while providing some mechanical support from the other direction

    Toxoplasma gondii and Neospora caninum infections in sheep and goats in Switzerland: Seroprevalence and occurrence in aborted foetuses.

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    Toxoplasma gondii and Neospora caninum infections are important causes of abortion in ruminants. Besides, meat from T. gondii infected animals represent a major infection source for humans. The occurrence of these protozoan parasites in Switzerland was investigated both, in a nationwide cross-sectional serological survey, and by molecular methods in aborted sheep and goat foetuses. A total of 653 sheep from 143 farms and 748 goats from 164 farms were tested by commercial ELISAs and inconclusive results were defined by immunoblot. Besides, a risk factor analysis for seropositivity was performed. The observed seroprevalences for T. gondii in sheep and goats were 66.3% and 50.5% at the animal level, and 90.9% and 81.1% at the farm level, respectively. For N. caninum, the detected seroprevalences in sheep and goats were 0.8% and 0.9% at the animal level, and 2.8% and 1.8% at the farm level, respectively. Older small ruminants, and sheep (vs. goats) had a higher risk of being seropositive to T. gondii. Alpine grazing in summer was identified as a protective factor for seropositivity to T. gondii in both animal species. Toxoplasma gondii and N. caninum DNA were detected in 6.1% and 2.4% (n = 82), and in 6.8% and 1.4% (n = 73) of the tested ovine and caprine foetuses, respectively. These results suggest the involvement of these parasites in abortions and reveal a high prevalence of T. gondii and lower prevalence of N. caninum infections in small ruminants in Switzerland. They also suggest that consumption of undercooked meat from T. gondii infected sheep and goats may represent a risk for public health

    Transformer-based normative modelling for anomaly detection of early schizophrenia

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    Despite the impact of psychiatric disorders on clinical health, early-stage diagnosis remains a challenge. Machine learning studies have shown that classifiers tend to be overly narrow in the diagnosis prediction task. The overlap between conditions leads to high heterogeneity among participants that is not adequately captured by classification models. To address this issue, normative approaches have surged as an alternative method. By using a generative model to learn the distribution of healthy brain data patterns, we can identify the presence of pathologies as deviations or outliers from the distribution learned by the model. In particular, deep generative models showed great results as normative models to identify neurological lesions in the brain. However, unlike most neurological lesions, psychiatric disorders present subtle changes widespread in several brain regions, making these alterations challenging to identify. In this work, we evaluate the performance of transformer-based normative models to detect subtle brain changes expressed in adolescents and young adults. We trained our model on 3D MRI scans of neurotypical individuals (N=1,765). Then, we obtained the likelihood of neurotypical controls and psychiatric patients with early-stage schizophrenia from an independent dataset (N=93) from the Human Connectome Project. Using the predicted likelihood of the scans as a proxy for a normative score, we obtained an AUROC of 0.82 when assessing the difference between controls and individuals with early-stage schizophrenia. Our approach surpassed recent normative methods based on brain age and Gaussian Process, showing the promising use of deep generative models to help in individualised analyses.Comment: 10 pages, 2 figures, 2 tables, presented at NeurIPS22@PAI4M

    A Search for Very Low-mass Stars and Brown Dwarfs in the Young sigma Orionis Cluster

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    We present a CCD-based photometric survey covering 870 sq. arcmin in a young stellar cluster around the young multiple star sigma Orionis. Our survey limiting R, I, and Z magnitudes are 23.2, 21.8, and 21.0, respectively. From our colour-magnitude diagrams, we have selected 49 faint objects, which smoothly extrapolate the photometric sequence defined by more massive known members. Adopting the currently accepted age interval of 2-10 Myr for the Orion 1b association and considering recent evolutionary models, our objects may span a mass range from 0.1 down to 0.02 Msun, well within the substellar regime. Follow-up low-resolution optical spectroscopy (635-920 nm) for eight of our candidates (I=16-19.5) shows that they have spectral types M6-M8.5 which are consistent with the expectations for true members. Compared with their Pleiades counterparts of similar types, Halpha emission is generally stronger, while NaI and KI absorption lines appear weaker, as expected for lower surface gravities and younger ages. Additionally, TiO bands and in particular VO bands appear clearly enhanced in our candidate with the latest spectral type, SOri 45 (M8.5, I=19.5), compared to objects of similar types in older clusters and the field. We have estimated the mass of this candidate at only 0.020-0.040 Msun, hence it is one of the least massive brown dwarfs yet discovered. We also discuss in this paper the potential role of deuterium as a tracer of both substellar nature and age in very young clusters.Comment: Accepted for publication in ApJ Main Journal. 32 pages of text and tables + 9 pages of figures. Figures 3a and 3b (gif format) provided separatel
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