4,759 research outputs found
Recent MOST space photometry
The Microvariability and Oscillations of STars (MOST) photometric satellite
has already undertaken more than 64 primary campaigns which include some
clusters and has obtained observations of >850 secondary stars of which ~180
are variable. More than half of the variables pulsate, with the majority being
of B-type. Since 2006 January, MOST has operated with only a single CCD for
both guiding and science. The resulting increase in read-out cadence has
improved precision for the brightest stars. The 2007 light curve for Procyon
confirms the lack of predicted p-modes with photometric amplitudes exceeding 8
ppm as we found in 2004 and 2005. p-modes have been detected in other
solar-type stars as well as pre-main sequence objects, roAp and delta Scuti
variables. g-modes have been detected in a range of slowly pulsating B stars,
Be stars and beta Cephei variables. Differential rotation has been defined for
several spotted solar-type stars and limits set to the albedo of certain
transiting planets and the presence of other perturbing planets. The mission is
expected to continue as long as the experiment operates.Comment: 9 pages, 7 figures, from HELAS-II meetin
Characteristics of patients who die of necrotizing enterocolitis
Objective:Necrotizing enterocolitis (NEC) is associated with high morbidity and mortality among infants admitted for intensive care. The factors associated with mortality and catastrophic presentation remain poorly understood. Our objective was to describe the factors associated with mortality in infants with NEC and to quantify the degree to which catastrophic presentation contributes to mortality in infants with NEC. Catastrophic NEC was defined before data analysis as NEC that led to death within 7 days of diagnosis.Study Design:We performed a retrospective review of the Pediatrix's Clinical Data Warehouse (1997 to 2009, n=560,227) to compare the demographic, therapeutic and outcome characteristics of infants who survived NEC vs those who died. Associations were tested by bivariate and multivariate analysis.Result:We compared the 5594 infants diagnosed with NEC and who were discharged home with 1505 infants diagnosed with NEC who died. In multivariate analysis, the factors associated with death (P<0.01 in analysis) were lower estimated gestational age, lower birth weight, treatment with assisted ventilation on the day of diagnosis of NEC, treatment with vasopressors at the time of diagnosis, and Black race. Patients who received only ampicillin and gentamicin on the day of diagnosis were less likely to die. Two-thirds of NEC deaths occurred quickly (<7 days from diagnosis), with a median time of death of one day from time of diagnosis. Infants who died within 7 days of diagnosis had a higher birth weight, more often were on vasopressors and high frequency ventilation at the time of diagnosis compared with patients who died at 7 or more days. Although mortality decreased with increasing gestational age, the proportion of deaths that occurred within 7 days was relatively consistent (65 to 75% of the patients who died) across all gestational ages.Conclusion:Mortality among infants who have NEC remains high and infants who die of NEC commonly (66%) die quickly. Most of the factors associated with mortality are related to immaturity, low birth weight and severity of illness
Limits to Interstellar C_4 and C_5 Towards zeta Ophiuchi
We have made a sensitive search for the origin bands in the known electronic
transitions of the linear carbon chains C_4 and C_5 at 3789 and 5109 A towards
zeta Oph (A_V <= 1). The incentive was a recent detection of C_3 in this
interstellar cloud with a column density of 1.6 x 10^12 cm^-2 plus the
availability of laboratory gas phase spectra of C_4 and C_5. Further, some
models of diffuse interstellar clouds predict that the abundance of these
latter species should be within an order of magnitude of C_3. Despite achieving
S/N of 2300 to 2600 per pixel at a resolution of ~110,000, the searches were
negative, leading to 3 sigma upper limits to the column density of N(C_5) = 2 x
10^11 cm^-2 and N(C_4) = 4 x 10^12-13 cm^-2 where these values rely on
theoretically calculated oscillator strengths. The implication of these limits
are discussed on the choice of molecules for study in future attempts to
identify the carriers of the stronger diffuse interstellar bands.Comment: 12 pages, 3 figure
Personality predictors of levels of forgiveness two and a half years after the transgression
The aim of the present study was to explore whether the domains and facets of the five-factor model of personality predicted motivational states for avoidance and revenge following a transgression at a second temporal point distant from the original transgression. A sample of 438 university students, who reported experiencing a serious transgression against them, completed measures of avoidance and revenge motivations around the transgression and five-factor personality domains and facets at time 1, and measures of avoidance and revenge motivations two and a half years later. The findings suggest that neuroticism, and specifically anger hostility, predicts revenge and avoidance motivation
Candida albicans Hypha Formation and Mannan Masking of ÎČ-Glucan Inhibit Macrophage Phagosome Maturation
Received 28 August 2014 Accepted 28 October 2014 Published 2 December 2014 This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license. ACKNOWLEDGMENTS We thank Janet Willment, Aberdeen Fungal Group, University of Aberdeen, for kindly providing the soluble Dectin-1-Fc reporter. All microscopy was performed with the assistance of the University of Aberdeen Core Microscopy & Histology Facility, and we thank the IFCC for their assistance with flow cytometry. We thank the Wellcome Trust for funding (080088, 086827, 075470, 099215, 097377, and 101873). E.R.B. and A.J.P.B. are funded by the European Research Council (ERC-2009-AdG-249793), and J.L. is funded by a Medical Research Council Clinical Training Fellowship.Peer reviewedPublisher PD
Predators in Natural Fragments: Foraging Ecology of Wolves in British Columbiaâs Central and North Coast Archipelago
Aim Predatorâprey dynamics in fragmented areas may be influenced by spatial features of the landscape. Although little is known about these processes, an increasingly fragmented planet underscores the urgency to predict its consequences. Accordingly, our aim was to examine foraging behaviour of an apex mammalian predator, the wolf (Canis lupus), in an archipelago environment.
Location Mainland and adjacent archipelago of British Columbia, Canada; a largely pristine and naturally fragmented landscape with islands of variable size and isolation.
Methods We sampled 30 mainland watersheds and 29 islands for wolf faeces in summers 2000 and 2001 and identified prey remains. We examined broad geographical patterns and detailed biogeographical variables (area and isolation metrics) as they relate to prey consumed. For island data, we used Akaike Information Criteria to guide generalized linear regression model selection to predict probability of black-tailed deer (main prey; Odocoileus hemionus) in faeces.
Results Black-tailed deer was the most common item in occurrence per faeces (63%) and occurrence per item (53%) indices, representing about 63% of mammalian biomass. Wolves consumed more deer on islands near the mainland (65% occurrence per item) than on the mainland (39%) and outer islands (45%), where other ungulates (mainland only) and small mammals replaced deer. On islands, the probability of detecting deer was influenced primarily by island distance to mainland (not by area or inter-landmass distance), suggesting limited recolonization by deer from source populations as a causal mechanism.
Main conclusions Although sampling was limited in time, consistent patterns among islands suggest that population dynamics in isolated fragments are less stable and can result in depletion of prey. This may have important implications in understanding predatorâprey communities in isolation, debate regarding wolfâ deer systems and logging in temperate rain forests, and reserve design
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Designing theoretically-informed implementation interventions
Clinical and health services research is continually producing new findings that may contribute to effective and efficient patient care. However, the transfer of research findings into practice is unpredictable and can be a slow and haphazard process. Ideally, the choice of implementation strategies would be based upon evidence from randomised controlled trials or systematic reviews of a given implementation strategy. Unfortunately, reviews of implementation strategies consistently report effectiveness some, but not all of the time; possible causes of this variation are seldom reported or measured by the investigators in the original studies. Thus, any attempts to extrapolate from study settings to the real world are hampered by a lack of understanding of the effects of key elements of individuals, interventions, and the settings in which they were trialled. The explicit use of theory offers a way of addressing these issues and has a number of advantages, such as providing: a generalisable framework within which to represent the dimensions that implementation studies address, a process by which to inform the development and delivery of interventions, a guide when evaluating, and a way to allow for an exploration of potential causal mechanisms. However, the use of theory in designing implementation interventions is methodologically challenging for a number of reasons, including choosing between theories and faithfully translating theoretical constructs into interventions. The explicit use of theory offers potential advantages in terms of facilitating a better understanding of the generalisability and replicability of implementation interventions. However, this is a relatively unexplored methodological area
Boolean delay equations on networks: An application to economic damage propagation
We introduce economic models based on Boolean Delay Equations: this formalism
makes easier to take into account the complexity of the interactions between
firms and is particularly appropriate for studying the propagation of an
initial damage due to a catastrophe. Here we concentrate on simple cases, which
allow to understand the effects of multiple concurrent production paths as well
as the presence of stochasticity in the path time lengths or in the network
structure.
In absence of flexibility, the shortening of production of a single firm in
an isolated network with multiple connections usually ends up by attaining a
finite fraction of the firms or the whole economy, whereas the interactions
with the outside allow a partial recovering of the activity, giving rise to
periodic solutions with waves of damage which propagate across the structure.
The damage propagation speed is strongly dependent upon the topology. The
existence of multiple concurrent production paths does not necessarily imply a
slowing down of the propagation, which can be as fast as the shortest path.Comment: Latex, 52 pages with 22 eps figure
A Planetary Companion to gamma Cephei A
We report on the detection of a planetary companion in orbit around the
primary star of the binary system Cephei. High precision radial
velocity measurements using 4 independent data sets spanning the time interval
1981--2002 reveal long-lived residual radial velocity variations superimposed
on the binary orbit that are coherent in phase and amplitude with a period or
2.48 years (906 days) and a semi-amplitude of 27.5 m s. We performed a
careful analysis of our Ca II H & K S-index measurements, spectral line
bisectors, and {\it Hipparcos} photometry. We found no significant variations
in these quantities with the 906-d period. We also re-analyzed the Ca II
8662 {\AA} measurements of Walker et al. (1992) which showed possible
periodic variations with the ``planet'' period when first published. This
analysis shows that periodic Ca II equivalent width variations were only
present during 1986.5 -- 1992 and absent during 1981--1986.5. Furthermore, a
refined period for the Ca II 8662 {\AA} variations is 2.14 yrs,
significantly less than residual radial velocity period. The most likely
explanation of the residual radial velocity variations is a planetary mass
companion with sin = 1.7 and an orbital semi-major axis
of 2.13 AU. This supports the planet hypothesis for the residual
radial velocity variations for Cep first suggested by Walker et al.
(1992). With an estimated binary orbital period of 57 years Cep is the
shortest period binary system in which an extrasolar planet has been found.
This system may provide insights into the relationship between planetary and
binary star formation.Comment: 19 pages, 15 figures, accepted in Ap. J. Includes additional data and
improved orbital solutio
Retrieval of Carbon Dioxide Vertical Profiles From Solar Occultation Observations and Associated Error Budgets for ACE-FTS and CASS-FTS
An algorithm is developed to retrieve the vertical profile of carbon dioxide in the 5 to 25 km altitude range using mid-infrared solar occultation spectra from the main instrument of the ACE (Atmospheric Chemistry Experiment) mission, namely the Fourier transform spectrometer (FTS). The main challenge is to find an atmospheric phenomenon which can be used for accurate tangent height determination in the lower atmosphere, where the tangent heights (THs) calculated from geometric and timing information are not of sufficient accuracy. Error budgets for the retrieval of CO2 from ACE-FTS and the FTS on a potential follow-on mission named CASS (Chemical and Aerosol Sounding Satellite) are calculated and contrasted. Retrieved THs have typical biases of 60m relative to those retrieved using the ACE version 3. x software after revisiting the temperature dependence of the N2 CIA (collision-induced absorption) laboratory measurements and accounting for sulfate aerosol extinction. After correcting for the known residual high bias of ACE version 3. x THs expected from CO2 spectroscopic/isotopic inconsistencies, the remaining bias for tangent heights determined with the N2 CIA is -20 m. CO2 in the 5-13 km range in the 2009-2011 time frame is validated against aircraft measurements from CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container), CONTRAIL (Comprehensive Observation Network for Trace gases by Airline), and HIPPO HIAPER Pole-to-Pole Observations), yielding typical biases of -1.7 ppm in the 5-13 km range. The standard error of these biases in this vertical range is 0.4 ppm. The multiyear ACE-FTS data set is valuable in determining the seasonal variation of the latitudinal gradient which arises from the strong seasonal cycle in the Northern Hemisphere troposphere. The annual growth of CO2 in this time frame is determined to be 2.6±0.4 ppm year-1, in agreement with the currently accepted global growth rate based on ground-based measurements
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