442 research outputs found

    Extreme Variability in a Broad Absorption Line Quasar

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    CRTS J084133.15+200525.8 is an optically bright quasar at z=2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitude of V~17.3 between 2002 and 2008. Then, over the following five years, the source slowly brightened by approximately one magnitude, to V~16.2. Only ~1 in 10,000 quasars show such extreme variability, as quantified by the extreme parameters derived for this quasar assuming a damped random walk model. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line (FeLoBAL) quasar with extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. We report the first definitive redshift for this source, based on the detection of broad H-alpha in a Keck/MOSFIRE spectrum. Absorption systems separated by several 1000 km/s in velocity show coordinated weakening in the depths of their troughs as the continuum flux increases. We interpret the broad absorption line variability to be due to changes in photoionization, rather than due to motion of material along our line of sight. This source highlights one sort of rare transition object that astronomy will now be finding through dedicated time-domain surveys.Comment: 6 pages, 4 figures; accepted for publication in Ap

    Collimation and asymmetry of the hot blast wave from the recurrent nova V745 Scorpii

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    The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 10^7K. X-ray line profiles are more sharply peaked than expected for a spherically-symmetric blast wave, with a full width at zero intensity of approximately 2400 km/s, a full width at half maximum of 1200 +/- 30 km/s and an average net blueshift of 165 +/- 10 km/s. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray emitting material is aligned close to the plane of the sky and most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations and near-infrared line widths indicates the explosion energy was approximately 10^43 erg, and confirms an ejected mass of approximately 10^-7 Msun. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating the white dwarf is gaining mass and is a supernova Type 1a progenitor candidate.Comment: To appear in the Astrophysical Journa

    Insomnia disorder

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    Insomnia disorder affects a large proportion of the population on a situational, recurrent or chronic basis and is among the most common complaints in medical practice. The disorder is predominantly characterized by dissatisfaction with sleep duration or quality and difficulties initiating or maintaining sleep, along with substantial distress and impairments of daytime functioning. It can present as the chief complaint or, more often, co-occurs with other medical or psychiatric disorders, such as pain and depression. Persistent insomnia has been linked with adverse long-term health outcomes, including diminished quality of life and physical and psychological morbidity. Despite its high prevalence and burden, the aetiology and pathophysiology of insomnia is poorly understood. In the past decade, important changes in classification and diagnostic paradigms have instigated a move from a purely symptom-based conceptualization to the recognition of insomnia as a disorder in its own right. These changes have been paralleled by key advances in therapy, with generic pharmacological and psychological interventions being increasingly replaced by approaches that have sleep-specific and insomnia-specific therapeutic targets. Psychological and pharmacological therapies effectively reduce the time it takes to fall asleep and the time spent awake after sleep onset, and produce a modest increase in total sleep time; these are outcomes that correlate with improvements in daytime functioning. Despite this progress, several challenges remain, including the need to improve our knowledge of the mechanisms that underlie insomnia and to develop more cost-effective, efficient and accessible therapies

    Practical Handbook of Curve Fitting

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    First volume in a three-part series. Book written by Sandra Lach Arlinghaus. Material underwent extensive classroom testing (pre and post publication in handbook form) in course created and taught by W. D. Drake and S. L. Arlinghaus: Population-Environment Dynamics--Transition Theory, NRE 545, School of Natural Resources and Environment, The University of Michigan (1991-1997). Links to published documents containing student work from this course appear elsewhere in Deep Blue.Worked real-world examples illustrate theoretical aspects of fitting curves to data. TABLE OF CONTENTS: | Introduction--Theoretical Background | Chapter 1, Population Data Analysis: Straight line curve-fitting--least squares; Exponential curve-fitting; Exponential curve-fitting with a lower bound; Logistic curve-fitting; Gompertz curve-fitting. | Chapter 2, Epidemiology Data Analysis: Consistent database construction; Mapping of data; Straight line curve-fitting-least squares; Root mean square error. | Chapter 3, Agriculture Data Analysis: Linear fitting--bounded; Bar charts; Default computer curves; Linear fitting--unbounded--simple use of least squares; Exponenital fitting--unbounded; Extrapolation of fitted curves--prediction. | Chapter 4, Biodiversity Data Analysis: Dot maps; Equal-area map projection; Geographic information systems; Map overlays; Feigenbaum's graphical analysis. | Chapter 5, Soils and Forestry Data Analysis: Simple cubic spline curve fitting; Interpolation using a cubic spline; Feigenbaum's graphical analysis. | Chapter 6, Education Data Analysis: Straight line curve-fitting--least squares; Residual plots; Root mean square error. | Chapter 7, Transportation and Communication Data Analysis: Historical maps; Space-filling measured by density; Rank-ordering; Fitting maps to empirical curves. | Chapter 8, Environmental Toxicity Data Analysis: Straight line curve-fitting--least squares; Fitting curves to maps. | Chapter 9, Urbanization Data Analysis: Straight line curve-fitting--least squares; Partitioning of data--scale transformation; Residual plots; Examination and removal of outliers. | Chapter 10, World Trade Data Analysis: Set-theoretic analysis of numerical structure of data; Partitioning of data; Organization techniques; Geometric self-similarity. | Index of Figure Captions and Table Titles. | Quotation from the Overview section of the Introduction. | "Computers offer even the casual user opportunities to handle data that were seldom dreamed of a decade ago. Most spreadsheets and other software packages that have some sort of analytic capability offer an option to graph input data; indeed, even many hand-held calculators do so. Default graphs generated by the computer often link points in a kind of follow the dots fashion; while this is a useful feature, default curves of this sort do not generally assign an equation to the curve. Thus, these curves cannot be projected nor can they be used for systematic interpolation between values. Many of the same software packages that offer default curves also permit the user to insert equations and to generate other graphs based on these equations. The problem is that the user new to this world often does not have the needed mathematical background. We offer a practical approach to showing how to fit curves; it is practical because it uses global real-world data and exposes the reader, as an important side benefit, to the problems encountered when using first-rate electronic (or other) data bases. The reader who is content to fit curves without some sort of mathematical discussion behind these efforts, but who understands that different choices of curves can forecast highly diverse alternative futures, should be able to use all the techniques in this handbook. This section is included because it is important that it be here should one wish it. | With any data set (presented in electronic or paper format), it is important first to examine the set for interesting or unusual patterns in the display. These patterns often influence decisions in choosing subsets of data and tools to analyze subsets. Thus, we encourage readers to approach any data set with a set of basic guidelines in mind and to browse it in a thoughtful manner. We offer the following as one set of guidelines; it will be repeated throughout, with commentary relating it to the databases selected in particular chapters. | Patterns in Data--What to Look For--| 1. What is the general orgainzation scheme of the entire set? Is it arranged alphabetically, numerically, or in some other fashion? | 2. Are the real-world entries in the Table (nations, states, counties) expressed as comparable units: For example, county data and national data are generally not comparable. | 3. Are the numerical entries in the Table expressed in comparable units? For example, data in one column might measure percentaes while data in another column might measure thousands of dollars--these columns would not be comparable. | 4. Are there gaps in the data? If so, what is their significance to the questions you wish to have the data answer?" |Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58759/1/HandbookCurveFitting.pd

    The Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of prostate carcinoma.

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    Prostate cancer is the most commonly diagnosed malignancy and second leading cause of cancer death among men in the United States. In recent years, several new agents, including cancer immunotherapies, have been approved or are currently being investigated in late-stage clinical trials for the management of advanced prostate cancer. Therefore, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel, including physicians, nurses, and patient advocates, to develop consensus recommendations for the clinical application of immunotherapy for prostate cancer patients. To do so, a systematic literature search was performed to identify high-impact papers from 2006 until 2014 and was further supplemented with literature provided by the panel. Results from the consensus panel voting and discussion as well as the literature review were used to rate supporting evidence and generate recommendations for the use of immunotherapy in prostate cancer patients. Sipuleucel-T, an autologous dendritic cell vaccine, is the first and currently only immunotherapeutic agent approved for the clinical management of metastatic castrate resistant prostate cancer (mCRPC). The consensus panel utilized this model to discuss immunotherapy in the treatment of prostate cancer, issues related to patient selection, monitoring of patients during and post treatment, and sequence/combination with other anti-cancer treatments. Potential immunotherapies emerging from late-stage clinical trials are also discussed. As immunotherapy evolves as a therapeutic option for the treatment of prostate cancer, these recommendations will be updated accordingly

    Dynamic Analysis of Vascular Morphogenesis Using Transgenic Quail Embryos

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    Background: One of the least understood and most central questions confronting biologists is how initially simple clusters or sheet-like cell collectives can assemble into highly complex three-dimensional functional tissues and organs. Due to the limits of oxygen diffusion, blood vessels are an essential and ubiquitous presence in all amniote tissues and organs. Vasculogenesis, the de novo self-assembly of endothelial cell (EC) precursors into endothelial tubes, is the first step in blood vessel formation [1]. Static imaging and in vitro models are wholly inadequate to capture many aspects of vascular pattern formation in vivo, because vasculogenesis involves dynamic changes of the endothelial cells and of the forming blood vessels, in an embryo that is changing size and shape. Methodology/Principal Findings: We have generated Tie1 transgenic quail lines Tg(tie1:H2B-eYFP) that express H2B-eYFP in all of their endothelial cells which permit investigations into early embryonic vascular morphogenesis with unprecedented clarity and insight. By combining the power of molecular genetics with the elegance of dynamic imaging, we follow the precise patterning of endothelial cells in space and time. We show that during vasculogenesis within the vascular plexus, ECs move independently to form the rudiments of blood vessels, all while collectively moving with gastrulating tissues that flow toward the embryo midline. The aortae are a composite of somatic derived ECs forming its dorsal regions and the splanchnic derived ECs forming its ventral region. The ECs in the dorsal regions of the forming aortae exhibit variable mediolateral motions as they move rostrally; those in more ventral regions show significant lateral-to-medial movement as they course rostrally. Conclusions/Significance: The present results offer a powerful approach to the major challenge of studying the relative role(s) of the mechanical, molecular, and cellular mechanisms of vascular development. In past studies, the advantages of the molecular genetic tools available in mouse were counterbalanced by the limited experimental accessibility needed for imaging and perturbation studies. Avian embryos provide the needed accessibility, but few genetic resources. The creation of transgenic quail with labeled endothelia builds upon the important roles that avian embryos have played in previous studies of vascular development

    Searching for periodicities in the MACHO light curve of LMC X-2

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    Using the exceptional long-term monitoring capabilities of the MACHO project, we present here the optical history of LMC X-2 for a continuous 6-yr period. These data were used to investigate the previously claimed periodicities for this source of 8.15 h and 12.54 d : we find upper amplitude limits of 0.10 mag and 0.09 mag, respectively.Comment: 4 pages, 4 figures. Minor changes, including title. MNRAS, in pres

    The Extraordinary X-ray Light Curve of the Classical Nova V1494 Aquilae (1999 #2) in Outburst: The Discovery of Pulsations and a "Burst"

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    V1494 Aql (Nova Aql 1999 No. 2) was discovered on 2 December 1999. We obtained Chandra ACIS-I spectra on 15 April and 7 June 2000 which appear to show only emission lines. Our third observation, on 6 August, showed that its spectrum had evolved to that characteristic of a Super Soft X-ray Source. We then obtained Chandra LETG+HRC-S spectra on 28 September (8 ksec) and 1 October (17 ksec). We analyzed the X-ray light curve of our grating observations and found both a short time scale ``burst'' and oscillations. Neither of these phenomena have previously been seen in the light curve of a nova in outburst. The ``burst'' was a factor of 10 rise in X-ray counts near the middle of the second observation, and which lasted about 1000 sec; it exhibited at least two peaks, in addition to other structure. Our time series analysis of the combined 25 ksec observation shows a peak at 2500 s which is present in independent analyses of both the zeroth order image and the dispersed spectrum and is not present in similar analyses of grating data for HZ 43 and Sirius B. Further analyses of the V1494 Aql data find other periods present which implies that we are observing non-radial g+ modes from the pulsating, rekindled white dwarf.Comment: ApJ accepte

    Reduction of parathyroid hormone with vitamin D supplementation in blacks: A randomized controlled trial

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    BACKGROUND: Response of parathyroid hormone (PTH) to vitamin D supplementation is determined by the baseline PTH level and change in vitamin D status. Conflicting reports in Blacks exist on the PTH response to vitamin D to supplementation. METHODS: During 3 winters from 2007-2010, 328 healthy Blacks (median age, 51 years) living in Boston, MA were randomized into a 4-arm, double-blind trial for 3 months of placebo, 1000, 2000, or 4000 IU of vitamin D3. PTH was measured in 254 participants at baseline and at the end of vitamin D supplementation period. RESULTS: The differences in PTH between baseline and 3 months were 3.93 pg/mL for those receiving placebo, -3.37 pg/mL for those receiving 1000 IU/d, -6.76 pg/mL for those receiving 2000 IU/d, and -8.99 pg/mL for those receiving 4000 IU/d ( -2.98 pg/mL for each additional 1000 IU/d of vitamin D3; p<0.001). CONCLUSION: We found a significant decrease in PTH with increasing doses of vitamin D supplementation up to intakes of 4000 IU/d in Blacks. Clinical Trials.gov: NCT0058563

    A Nationally Representative Survey Assessing Restorative Sleep in US Adults

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    Restorative sleep is a commonly used term but a poorly defined construct. Few studies have assessed restorative sleep in nationally representative samples. We convened a panel of 7 expert physicians and researchers to evaluate and enhance available measures of restorative sleep. We then developed the revised Restorative Sleep Questionnaire (REST-Q), which comprises 9 items assessing feelings resulting from the prior sleep episode, each with 5-point Likert response scales. Finally, we assessed the prevalence of high, somewhat, and low REST-Q scores in a nationally representative sample of US adults (n= 1,055) and examined the relationship of REST-Q scores with other sleep and demographic characteristics. Pairwise correlations were performed between the REST-Q scores and other self-reported sleep measures. Weighted logistic regression analyses were conducted to compare scores on the REST-Q with demographic variables. The prevalence of higher REST-Q scores (4 or 5 on the Likert scale) was 28.1% in the nationally representative sample. REST-Q scores positively correlated with sleep quality (r=0.61) and sleep duration (r=0.32), and negatively correlated with both difficulty falling asleep (r=-0.40) and falling back asleep after waking (r=-0.41). Higher restorative sleep scores (indicating more feelings of restoration upon waking) were more common among those who were: ≥60 years of age (OR=4.20, 95%CI: 1.92-9.17); widowed (OR=2.35, 95%CI:1.01-5.42), and retired (OR=2.02, 95%CI:1.30-3.14). Higher restorative sleep scores were less frequent among those who were not working (OR=0.36, 95%CI: 0.10-1.00) and living in a household with two or more persons (OR=0.51,95%CI:0.29-0.87). Our findings suggest that the REST-Q may be useful for assessing restorative sleep
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