945 research outputs found

    Resolving the Surfaces of Extrasolar Planets With Secondary Eclipse Light Curves

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    We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially resolve its central star. We evaluate the feasibility of this technique for the HD 209458 system [..]. We consider two representations of the planetary thermal emission; a simple model parameterized by a sinusoidal dependence on longitude and latitude, as well as the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal offset in the geometric and photometric centroids of the hemisphere of the planet visible near opposition. To quantify this signal, we define a new parameter, the ``uniform time offset,'' which measures the time lag between the observed secondary eclipse and that predicted by a planet with a uniform surface flux distribution. We compare the predicted amplitude of this parameter for HD 209458 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6um a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands (4.5um, 5.8um, and 8.0um), and find that a modest improvement in photometric precision (as might be realized through observations of several eclipse events) should permit a similarly robust detection.Comment: AASTeX 5.2, 24 pages, 5 figures, accepted for publication in ApJ; v2: clarifications, updated to version accepted by ApJ; v3: try to reduce spacin

    Greenhouse and Field Evaluations of Entomopathogenic Nematodes (Nematode: Heterorhabditidae and Steinernematidae) for Control of Cabbage Maggot (Diopters: Anthomyiidae) on Cabbage

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    Entomb pathogenic nematodes-Heterorhabditis bacteriophora Poinar (Oswego strain), Steinenema carpocapsae (Weiser) (NY001 strain), Steinemema carpocapsae (25 strain), Steinemema feltiae Filipjev (=Neoaplectana carpocapsae Weiser) (369 strain), Steinernema feltiae (27 strain), and Steinernema riobravus Cabanillas and Poinar (355 strain)-were examined for pathogenicity against cabbage maggot, Delia radicum (L.), larvae in the greenhouse and field. Applications (per plant) of 3,000 and 4,000 infective juveniles of S. feltiae (369 strain), 30,000 infective juveniles of H. bacteriophora (Oswego strain), and 300 and 30,000 infective juveniles of S. feltiae (27 strain) reduced the number of D. radicum that developed to pupae on potted cabbage plants. H. bacteriophora (Oswego) at applications of 3,000 and 30,000 infective juveniles per plant and S. feltiae (27 strain) at applications of 30,000 (but not 3,000) infective juveniles per plant significantly reduced root damage caused by larvae of D. radicum. Logarithmically increased dosages between 100 and 100,000 infective juveniles per plant of S. feltiae (27 strain) linearly reduced the number of D. radicum pupae that developed on potted cabbage plants and the damage caused to the roots by D. radicullarvae. Root and stem dry weights of cabbage plants infested with D. radicum were significantly greater for plants inoculated with 100,000 infective juveniles of S. feltiae (27 strain) than for plants not inoculated with nematodes. Nematode inoculation did not prevent significant losses in root or stem dry weights at dosages less than 100,000 infective juveniles per plant. Soil surface applications of 100,000 and 200,000 infective juveniles per plant of S. feltiae (27 strain) were more effective than subsurface applications in preventing damage by natural or augmented populations of D. radicum larvae on cabbage in the field. However, mortality rates of wax moth larvae exposed to soil samples treated with S. feltiae (27 strain) suggested that this nematode showed greater persistence when applied beneath rather than on the soil surfac

    Contrasting strategies of hydraulic control in two codominant temperate tree species

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    Biophysical controls on plant water status exist at the leaf, stem, and root levels. Therefore, we pose that hydraulic strategy is a combination of traits governing water use at each of these three levels. We studied sap flux, stem water storage, stomatal conductance, photosynthesis, and growth of red oaks (Quercus rubra) and red maples (Acer rubrum). These species differ in stomatal hydraulic strategy and xylem architecture and may root at different depths. Stable isotope analysis of xylem water was used to identify root water uptake depth. Oaks were shown to access a deeper water source than maples. During non‐limiting soil moisture conditions, transpiration was greater in maples than in oaks. However, during a soil dry down, transpiration and stem water storage decreased by more than 80% and 28% in maples but only by 31% and 1% in oaks. We suggest that the preferential use of deep water by red oaks allows the species to continue transpiration and growth during soil water limitations. In this case, deeper roots may provide a buffer against drought‐induced mortality. Using 14 years of growth data, we show that maple growth correlates with mean annual soil moisture at 30 cm but oak growth does not. The observed responses of oak and maple to drought were not able to be explained by leaf and xylem physiology alone. We employed the Finite‐difference Ecosystem‐scale Tree Crown Hydrodynamics model version 2 plant hydrodynamics model to demonstrate the influence of root, stem, and leaf controls on tree‐level transpiration. We conclude that all three levels of hydraulic traits are required to define hydraulic strategy.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136732/1/eco1815_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136732/2/eco1815.pd

    Bayesian echo classification for Australian single-polarization weather radar with application to assimilation of radial velocity observations

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    The Australian Bureau of Meteorology’s operational weather radar network comprises a heterogeneous radar collection covering diverse geography and climate. A naïve Bayes classifier has been developed to identify a range of common echo types observed with these radars. The success of the classifier has been evaluated against its training dataset and by routine monitoring. The training data indicate that more than 90% of precipitation may be identified correctly. The echo types most difficult to distinguish from rainfall are smoke, chaff, and anomalous propagation ground and sea clutter. Their impact depends on their climatological frequency. Small quantities of frequently misclassified persistent echo (like permanent ground clutter or insects) can also cause quality control issues. The Bayes classifier is demonstrated to perform better than a simple threshold method, particularly for reducing misclassification of clutter as precipitation. However, the result depends on finding a balance between excluding precipitation and including erroneous echo. Unlike many single-polarization classifiers that are only intended to extract precipitation echo, the Bayes classifier also discriminates types of nonprecipitation echo. Therefore, the classifier provides the means to utilize clear air echo for applications like data assimilation, and the class information will permit separate data handling of different echo types

    Differences in health care use and outcomes by the timing of in-hospital worsening heart failure

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    BACKGROUND: Patients hospitalized with acute heart failure may experience worsening symptoms requiring escalation of therapy. In-hospital worsening heart failure is associated with worse in-hospital and postdischarge outcomes, but associations between the timing of worsening heart failure and outcomes are unknown. METHODS: Using data from a large clinical registry linked to Medicare claims, we examined characteristics, outcomes, and costs of patients hospitalized for acute heart failure. We defined in-hospital worsening heart failure by the use of inotropes or intravenous vasodilators or initiation of mechanical circulatory support, hemodialysis, or ventilation. The study groups were early worsening heart failure (n = 1,990), late worsening heart failure (n = 4,223), complicated presentation (n = 15,361), and uncomplicated hospital course (n = 41,334). RESULTS: Among 62,908 patients, those with late in-hospital worsening heart failure had higher in-hospital and postdischarge mortality than patients with early worsening heart failure or complicated presentation. Those with early or late worsening heart failure had more frequent all-cause and heart failure readmissions at 30 days and 1 year, with resultant higher costs, compared with patients with an uncomplicated hospital course. CONCLUSION: Although late worsening heart failure was associated with the highest mortality, both early and late worsening heart failures were associated with more frequent readmissions and higher health care costs compared to uncomplicated hospital course. Prevention of worsening heart failure may be an important focus in the care of hospitalized patients with acute heart failure

    Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared

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    We report spectroscopic and photometric observations of the Type IIb SN 2011dh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2,000 Angstroms in the UV to 2.4 microns in the NIR. Optical spectra provide line profiles and velocity measurements of HI, HeI, CaII and FeII that trace the composition and kinematics of the SN. NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the STIS reveals that the UV flux for SN 2011dh is low compared to other SN IIb. The HI and HeI velocities in SN 2011dh are separated by about 4,000 km/s at all phases. We estimate that the H-shell of SN 2011dh is about 8 times less massive than the shell of SN 1993J and about 3 times more massive than the shell of SN 2008ax. Light curves (LC) for twelve passbands are presented. The maximum bolometric luminosity of 1.8±0.2×10421.8 \pm 0.2 \times 10^{42} erg s−1^{-1} occurred about 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations and increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9 and 1% on day 34. We compare the bolometric light curves of SN 2011dh, SN 2008ax and SN 1993J. The LC are very different for the first twelve days after the explosions but all three SN IIb display similar peak luminosities, times of peak, decline rates and colors after maximum. This suggests that the progenitors of these SN IIb may have had similar compositions and masses but they exploded inside hydrogen shells that that have a wide range of masses. The detailed observations presented here will help evaluate theoretical models for this supernova and lead to a better understanding of SN IIb.Comment: 23 pages, 14 figures, 9 tables, accepted by Ap

    Overlap between general factors of psychopathology and personality : they share associations with daily life functioning and communication style

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    Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Previous studies have shown that specific personality dimensions, -e.g., the Big Five-, consistently intercorrelate, such that they form a general factor of personality (GFP). It has been hypothesized that the GFP reflects social effectiveness. Similarly, in the clinical domain, overlap between various psychopathological symptoms has also been reported, leading to a general factor of Psychopathology, or p factor. The aim of this study was to test the overlap between the higher order factors in personality and psychopathology, and how they relate to daily life functioning and communication style. We tested a sample of 165 outpatients of a psychological therapy institute, using a multi-source approach that included self-reports and other ratings. The outpatients’ self-reports of personality, general psychological problems, and interpersonal problems were available. Psychotherapists rated the outpatients’ functioning in daily life with the well-known Global Assessment of Functioning (GAF) scale. A spouse or friend also rated the impact of the patient’s communication/social behavior. Patients with lower GFP scores and higher scores on general psychopathology, displayed more distress and daily functioning deficits (i.e., lower GAF scores) and, in terms of communication styles, were also rated as being less dominant, less in control socially, and more submissive and aggressive. We proposed that part of the overlap between the general factors (GFP, psychopathology factors) may relate to a lower general life functioning and less social effectiveness

    Type Ia Supernova Rate Measurements To Redshift 2.5 From CANDELS: Searching For Prompt Explosions In The Early Universe

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    dThe Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of -0.25 deg2 with -900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z 2.5. We classify -24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z =- 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only -3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation ( 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions-though further analysis and larger samples will be needed to examine that suggestion. Key words: infrared: general - supernovae:Astronom

    SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion

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    We report evidence for excess blue light from the Type Ia supernova SN 2012cg at fifteen and sixteen days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN~Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected M_B = -19.62 +/- 0.02 mag and Delta m_{15}(B) = 0.86 +/- 0.02. Our data set is extensive, with photometry in 7 filters from 5 independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity v_{Si} = -10,500$ km s^{-1}. Comparing the early data with models by Kasen (2010) favors a main-sequence companion of about 6 solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.Comment: accepted to Ap

    Interacting effects of soil fertility and atmospheric CO 2 on leaf area growth and carbon gain physiology in Populus × euramericana (Dode) Guinier

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    Two important processes which may limit productivity gains in forest ecosystems with rising atmospheric CO 2 are reduction in photosynthetic capacity following prolonged exposure to high CO 2 and diminution of positive growth responses when soil nutrients, particularly N, are limiting. To examine the interacting effects of soil fertility and CO 2 enrichment on photosynthesis and growth in trees we grew hybrid poplar ( Populus × euramericana ) for 158 d in the field at ambient and twice ambient CO 2 and in soil with low or high N availability. We measured the timing and rate of canopy development, the seasonal dynamics of leaf level photosynthetic capacity, respiration, and N and carbohydrate concentration, and final above- and belowground dry weight. Single leaf net CO 2 assimilation (A) increased at elevated CO 2 over the majority of the growing season in both fertility treatments. At high fertility, the maximum size of individual leaves, total leaf number, and seasonal leaf area duration (LAD) also increased at elevated CO 2 , leading to a 49% increase in total dry weight. In contrast, at low fertility leaf area growth was unaffected by CO 2 treatment. Total dry weight nonetheless increased 25% due to CO 2 effects on A. Photosynthetic capacity (A at constant internal p(CO 2 ), (( C 1 )) was reduced in high CO 2 plants after 100 d growth at low fertility and 135 d growth at high fertility. Analysis of A responses to changing C 1 indicated that this negative adjustment of photosynthesis was due to a reduction in the maximum rate of CO 2 fixation by Rubisco. Maximum rate of electron transport and phosphate regeneration capacity were either unaffected or declined at elevated CO 2 . Carbon dioxide effects on leaf respiration were most pronounced at high fertility, with increased respiration mid-season and no change (area basis) or reduced (mass basis) respiration late-season in elevated compared to ambient CO 2 plants. This temporal variation correlated with changes in leaf N concentration and leaf mass per area. Our results demonstrate the importance of considering both structural and physiological pathways of net C gain in predicting tree responses to rising CO 2 under conditions of suboptimal soil fertility.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65655/1/j.1469-8137.1995.tb04295.x.pd
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