4,262 research outputs found

    Supernova pencil beam survey

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    Type Ia supernovae (SNe Ia) can be calibrated to be good standard candles at cosmological distances. We propose a supernova pencil beam survey that could yield between dozens to hundreds of SNe Ia in redshift bins of 0.1 up to z=1.5z=1.5, which would compliment space based SN searches, and enable the proper consideration of the systematic uncertainties of SNe Ia as standard candles, in particular, luminosity evolution and gravitational lensing. We simulate SNe Ia luminosities by adding weak lensing noise (using empirical fitting formulae) and scatter in SN Ia absolute magnitudes to standard candles placed at random redshifts. We show that flux-averaging is powerful in reducing the combined noise due to gravitational lensing and scatter in SN Ia absolute magnitudes. The SN number count is not sensitive to matter distribution in the universe; it can be used to test models of cosmology or to measure the SN rate. The SN pencil beam survey can yield a wealth of data which should enable accurate determination of the cosmological parameters and the SN rate, and provide valuable information on the formation and evolution of galaxies. The SN pencil beam survey can be accomplished on a dedicated 4 meter telescope with a square degree field of view. This telescope can be used to conduct other important observational projects compatible with the SN pencil beam survey, such as QSOs, Kuiper belt objects, and in particular, weak lensing measurements of field galaxies, and the search for gamma-ray burst afterglows.Comment: Final version, to appear in ApJ, 531, #2 (March 10, 2000). 22 pages including 5 figures. Improved presentatio

    Bringing Background into the Foreground: Making All Classes Equal in Weakly-supervised Video Semantic Segmentation

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    Pixel-level annotations are expensive and time-consuming to obtain. Hence, weak supervision using only image tags could have a significant impact in semantic segmentation. Recent years have seen great progress in weakly-supervised semantic segmentation, whether from a single image or from videos. However, most existing methods are designed to handle a single background class. In practical applications, such as autonomous navigation, it is often crucial to reason about multiple background classes. In this paper, we introduce an approach to doing so by making use of classifier heatmaps. We then develop a two-stream deep architecture that jointly leverages appearance and motion, and design a loss based on our heatmaps to train it. Our experiments demonstrate the benefits of our classifier heatmaps and of our two-stream architecture on challenging urban scene datasets and on the YouTube-Objects benchmark, where we obtain state-of-the-art results.Comment: 11 pages, 4 figures, 7 tables, Accepted in ICCV 201

    A New Local Temperature Distribution Function for X-ray Clusters: Cosmological Applications

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    (abridged) We present a new determination of the local temperature function of X-ray clusters. We use a new sample comprising fifty clusters for which temperature information is now available, making it the largest complete sample of its kind. It is therefore expected to significantly improve the estimation of the temperature distribution function of moderately hot clusters. We find that the resulting temperature function is higher than previous estimations, but agrees well with the temperature distribution function inferred from the BCS and RASS luminosity function. We have used this sample to constrain the amplitude of the matter fluctuations on cluster's scale of 8Ω031h18\sqrt[3]{\Omega_0}^{-1}h^{-1}Mpc, assuming a mass-temperature relation based on recent numerical simulations. We find σ8=0.6±0.02\sigma_8 = 0.6\pm 0.02 for an Ω0=1\Omega_0 = 1 model. Our sample provides an ideal reference at z0z \sim 0 to use in the application of the cosmological test based on the evolution of X-ray cluster abundance (Oukbir & Blanchard 1992, 1997). Using Henry's sample, we find that the abundance of clusters at z=0.33z = 0.33 is significantly smaller, by a factor larger than 2, which shows that the EMSS sample provides strong evidence for evolution of the cluster abundance. A likelihood analysis leads to a rather high value of the mean density parameter of the universe: Ω=0.92±0.22\Omega =0.92 \pm 0.22 (open case) and Ω=0.86±0.25\Omega =0.86 \pm 0.25 (flat case), which is consistent with a previous, independent estimation based on the full EMSS sample by Sadat et al.(1998). Some systematic uncertainties which could alter this result are briefly discussed.Comment: 31 pages, 12 figures, mathches the version published in Astronomy and Astrophysic

    Comparison of Knee-High and Thigh-High Graduated Compression Stockings in Preventing Deep Vein Thrombosis in Patients with Hemorrhagic Stroke

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    Background: Deep Vein Thrombosis (DVT) is a common complication in patients with hemorrhagic stroke. Prophylaxis and treatment of DVT in these patients is very difficult because there are some limitations regarding the use of anticoagulant drugs. Objectives: The purpose of this study was to compare the effectiveness of knee-high and thigh-high graduated compression stockings in preventing DVT in patients with hemorrhagic stroke. Methods: In this clinical trial, 88 patients with hemorrhagic stroke were randomly assigned to two groups to receive either thighhigh or knee-high graduated compression stockings as prophylaxis for DVT. The prevalence of DVT was studied using clinical symptoms and Doppler ultrasound. Chi-square and Mann Whitney U tests were used to analyze the data. Results: In the thigh-high stockings group, 11 patients (26.8%) and in the knee-high stockings group, 18 patients (38.3%) were affected by DVT during the study. However, no significant difference was observed between the two groups (P = 0.25). Conclusions: There was no significant difference between the two groups in the incidence of DVT. Therefore, either knee-high or thigh-high stockings can be used as prophylaxis, depending on patients’ will, cost and ease of use

    Effect of Ginger on Relieving Nausea and Vomiting in Pregnancy: A Randomized, Placebo-Controlled Trial

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    Background: Nausea and vomiting are common and unpleasant complications in pregnancy. Although many alternative therapists support the use of ginger for nausea and vomiting of pregnancy, there is currently insufficient clinical evidence to support its use in this condition Objectives: The present study was performed to assess the effectiveness of ginger in the treatment of nausea and vomiting in pregnancy. Patients and Methods: This seven-day clinical trial was performed on 120 eligible pregnant women with symptoms of mild to moderate nausea and vomiting before 16 weeks gestation. They were divided into; ginger, placebo and control groups, by block randomization. Women were asked to record their nausea and vomiting for three days, and then participants received either ginger capsules, or a placebo for four days. No intervention was done with the control group. Data measure was self-recorded symptoms according to the Rhodes Index. Data were analyzed by ANOVA, ANCOVA, Kruskal-Wallis, Chi-square, and Fisher’s exact test, for the quantitative and qualitative variables. Results: There were no statistical differences in the baseline demographics between the three groups apart from age of marriage and wanted or unwanted pregnancy. An ANCOVA test (covariance test) showed significant differences in mean scores after the intervention in the three groups (P < 0.001). Conclusions: Ginger was effective for the relief of mild to moderate nausea and vomiting in pregnant women at less than 16 weeks gestation

    The Expected Rate of Gamma-Ray Burst Afterglows In Supernova Searches

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    We predict the rate at which Gamma-Ray Burst (GRB) afterglows should be detected in supernova searches as a function of limiting flux. Although GRB afterglows are rarer than supernovae, they are detectable at greater distances because of their higher intrinsic luminosity. Assuming that GRBs trace the cosmic star formation history and that every GRB gives rise to a bright afterglow, we find that the average detection rate of supernovae and afterglows should be comparable at limiting magnitudes brighter than K=18. The actual rate of afterglows is expected to be somewhat lower since only a fraction of all gamma-ray selected GRBs were observed to have associated afterglows. However, the rate could also be higher if the initial gamma-ray emission from GRB sources is more beamed than their late afterglow emission. Hence, current and future supernova searches can place strong constraints on the afterglow appearance fraction and the initial beaming angle of GRB sources.Comment: 13 pages, submitted to ApJ

    Prevalence and Severity of Menopausal Symptoms and Related Factors Among Women 40-60 Years in Kashan, Iran

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    Background: Menopause is a unique event in a woman’s life which has many symptoms. Frequency and severity of these symptoms vary, and they are based on the woman’s epidemiological characteristics. Objectives: The aim of this study was to determine the prevalence and severity of menopausal symptoms and related factors among women, 40-60 years in Kashan, Iran. Patients and Methods: In this cross-sectional study, 700 menopausal women in Kashan City were selected using cluster sampling. Data were collected by the Menopause Quality of Life Questionnaire (MENQOL). In addition, demographic variables including; current age, age of menarche and menopause, marital status, educational level, working status and exercise activity levels, were recorded. Data were analyzed using SPSS software version 16 and socio-demographic characteristics were compared using a chi-square test. A P value < 0.05 was considered significant. Results: The most common symptoms in; vasomotor, psychosocial, physical and sexual domains were; ‘night sweats’, ‘accomplishing less than I used to’, ‘feeling a lack of energy’, and ‘change in sexual desire’, respectively. Moreover, the most severe symptoms in these domains were; ‘night sweats’, ‘feeling anxious or nervous’, ‘aching muscles or joints’, and ‘avoiding intimacy’. There was a statistically significant difference between; the severity of menopausal symptoms and working status (P = 0.017), different educational levels (P = 0.001), exercise activity (P = 0.001), exercise frequency (P = 0.04), and duration of menopause (P = 0.03). Conclusions: The prevalence of menopausal symptoms in our population is similar to most other communities. Employment, higher educational levels, doing physical activity and duration of menopause of more than five years is associated with milder menopausal symptoms

    XMMNewtonXMM-Newton Ω\Omega project: III. Gas mass fraction shape in high redshift clusters

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    We study the gas mass fraction, f_gas,f\_{\rm gas}, behavior in XMMNewtonXMM-Newton Ω\Omega project. The typical f_gasf\_{\rm gas} shape of high redshift galaxy clusters follows the global shape inferred at low redshift quite well. This result is consistent with the gravitational instability picture leading to self similar structures for both the dark and baryonic matter. However, the mean f_gasindistantclustersshowssomedifferencestolocalones,indicatingadeparturefromstrictscaling.Thisresultisconsistentwiththeobservedevolutionintheluminositytemperaturerelation.Wequantitativelyinvestigatethisdeparturefromscalinglaws.Withinthelocalsampleweused,amoderatebutclearvariationoftheamplitudeofthegasmassfractionwithtemperatureisfound,atrendthatweakensintheouterregions.Thesevariationsdonotexplaindeparturefromscalinglawsofourdistantclusters.Animportantimplicationofourresultsisthatthegasfractionevolution,atestofthecosmologicalparameters,canleadtobiasedvalueswhenappliedatradiismallerthanthevirialradius.Fromourf\_{\rm gas} in distant clusters shows some differences to local ones, indicating a departure from strict scaling. This result is consistent with the observed evolution in the luminosity-temperature relation. We quantitatively investigate this departure from scaling laws. Within the local sample we used, a moderate but clear variation of the amplitude of the gas mass fraction with temperature is found, a trend that weakens in the outer regions. These variations do not explain departure from scaling laws of our distant clusters. An important implication of our results is that the gas fraction evolution, a test of the cosmological parameters, can lead to biased values when applied at radii smaller than the virial radius. From our XMM$ clusters, the apparent gas fraction at the virial radius is consistent with a non-evolving universal value in a high matter density model and not with a concordance.Comment: Accepted, A&A, in pres
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