2,015 research outputs found
Preliminary vegetation map of the Espenberg Peninsula, Alaska, based on an Earth Resources Technology Satellite image
There are no author-identified significant results in this report
AGAPE, an experiment to detect MACHO's in the direction of the Andromeda galaxy
The status of the Agape experiment to detect Machos in the direction of the
andromeda galaxy is presented.Comment: 4 pages, 1 figure in a separate compressed, tarred, uuencoded uufile.
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Quantification of valvular regurgitation by cardiac blood pool scintigraphy: correlation with catheterization
The diagnosis of valvular regurgitation (R) is usually based on clinical signs. Quantification conventionally requires catheterization (C). We have quantified R with cardiac blood pool scintigraphy (CBPS) and compared the results with those obtained by C. Regurgitant fraction (RF) determined by C was calculated with the technique of Dodge. Forward output was measured by thermodilution or cardiogreen dilution. The RF at CBPS was obtained by the stroke index ratio (SIR) minus 1.2 divided by SIR, where SIR is the ratio of the stroke counts of left venticle over those of the right ventricle. Stroke counts are calculated directly from the time-activity curves. Each time-activity curve was obtained by drawing one region of interest around each diastolic image. The correction factor (1.2) was calculated from a large normal population. 22 patients had aortic R, 7 mitral R, 12 both, 8 patients had no evidence of regurgitation. RF of the patients with R varied from 27 to 71% (x = 42%) at C and from 26 to 74% (Y = 41%) at CBPS. Linear regression shows a good correlation coefficient (r = 0.82). The regression equation is y = 0.93x + 1.8. No correlation was found between RF (CBPS or C) and the severity of R assessed visually from angiography. In conclusion: CBPS, a non-invasive method, allows easy and repeatable determination of RF and correlates well with data obtained at catheterizatio
AgapeZ1: a Large Amplification Microlensing Event or an Odd Variable Star Towards the Inner Bulge of M31
AgapeZ1 is the brightest and the shortest duration microlensing candidate
event found in the Agape data. It occured only 42" from the center of M31. Our
photometry shows that the half intensity duration of the event6 is 4.8 days and
at maximum brightness we measure a stellar magnitude of R=18.0 with B-R=0.80
mag color. A search on HST archives produced a single resolved star within the
projected event position error box. Its magnitude is R=22.Comment: 4 pages with 5 figure
Early risk factors for hyperactivity-impulsivity and inattention trajectories from age 17 months to 8 years.
CONTEXT: Attention-deficit/hyperactivity disorder is an etiologically heterogeneous neurodevelopmental condition with long-term negative outcomes. However, the early developmental course of hyperactivity-impulsivity and inattention symptoms and their association with previous environmental risk factors are still poorly understood OBJECTIVES: To describe the developmental trajectories of hyperactivity-impulsivity and inattention symptoms and to identify their prenatal, perinatal, and postnatal risk factors. DESIGN: Birth cohort from the general population. SETTING: Quebec Longitudinal Study of Child Development. PARTICIPANTS: The sample consisted of 2057 individuals, followed up from age 5 months to 8 years. MAIN OUTCOME MEASURES: Prenatal, perinatal, and postnatal risk factors assessed at age 5 months were considered predictors of group membership in high hyperactivity-impulsivity and inattention trajectories from age 17 months to 8 years. RESULTS: The frequency of hyperactivity-impulsivity symptoms tended to slightly decrease with age, whereas the frequency of inattention symptoms substantially increased up to age 6 years. However, trajectories of hyperactivity-impulsivity and inattention symptoms were significantly associated with each other. Risk factors for high trajectories of both types of symptoms were premature birth (adjusted odds ratio [aOR], 1.93; 95% CI, 1.07-3.50), low birth weight (2.11; 1.12-3.98), prenatal tobacco exposure (1.41; 1.03-1.93), nonintact family (1.85; 1.26-2.70), young maternal age at birth of the target child (1.78; 1.17-2.69), paternal history of antisocial behavior (1.78; 1.28-2.47), and maternal depression (1.35; 1.18-1.54). CONCLUSIONS: A large range of early risk factors, including prenatal, perinatal social, and parental psychopathology variables, act independently to heighten the likelihood of having persistently high levels of hyperactivity-impulsivity and inattention symptoms from infancy to middle childhood. Early interventions should be experimented with to provide effective tools for attention-deficit/hyperactivity disorder prevention
Difference Image Analysis of Galactic Microlensing I. Data Analysis
This is a preliminary report on the application of Difference Image Analysis
(DIA) to galactic bulge images. The aim of this analysis is to increase the
sensitivity to the detection of gravitational microlensing. We discuss how the
DIA technique simplifies the process of discovering microlensing events by
detecting only objects which have variable flux. We illustrate how the DIA
technique is not limited to detection of so called ``pixel lensing'' events,
but can also be used to improve photometry for classical microlensing events by
removing the effects of blending. We will present a method whereby DIA can be
used to reveal the true unblended colours, positions and light curves of
microlensing events. We discuss the need for a technique to obtain the accurate
microlensing time scales from blended sources, and present a possible solution
to this problem using the existing HST colour magnitude diagrams of the
galactic bulge and LMC. The use of such a solution with both classical and
pixel microlensing searches is discussed. We show that one of the major causes
of systematic noise in DIA is differential refraction. A technique for removing
this systematic by effectively registering images to a common airmass is
presented. Improvements to commonly used image differencing techniques are
discussed.Comment: 18 pages, 8 figures, uses AAS LaTEX 4.0, To appear in Astrophysical
Journa
Variability in Antarctic surface climatology across regional climate models and reanalysis datasets
Regional climate models (RCMs) and reanalysis datasets provide valuable information for assessing the vulnerability of ice shelves to collapse over Antarctica, which is important for future global sea level rise estimates. Within this context, this paper examines variability in snowfall, near-surface air temperature and melt across products from the Met Office Unified Model (MetUM), Regional Atmospheric Climate Model (RACMO) and Modèle Atmosphérique Régional (MAR) RCMs, as well as the ERA-Interim and ERA5 reanalysis datasets. Seasonal and trend decomposition using LOESS (STL) is applied to split the monthly time series at each model grid cell into trend, seasonal and residual components. Significant systematic differences between outputs are shown for all variables in the mean and in the seasonal and residual standard deviations, occurring at both large and fine spatial scales across Antarctica. Results imply that differences in the atmospheric dynamics, parametrisation, tuning and surface schemes between models together contribute more significantly to large-scale variability than differences in the driving data, resolution, domain specification, ice sheet mask, digital elevation model and boundary conditions. Despite significant systematic differences, high temporal correlations are found for snowfall and near-surface air temperature across all products at fine spatial scales. For melt, only moderate correlation exists at fine spatial scales between different RCMs and low correlation between RCM and reanalysis outputs. Root mean square deviations (RMSDs) between all outputs in the monthly time series for each variable are shown to be significant at fine spatial scales relative to the magnitude of annual deviations. Correcting for systematic differences results in significant reductions in RMSDs, suggesting the importance of observations and further development of bias-correction techniques
ISOCAM OBSERVATIONS OF M31
Abstract We present ISOCAM images of the Andromeda galaxy center. They display an elliptical stellar bulge and a more complexe dust distribution. The spatial dust distribution follows a mini-spiral structure identical to the distribution of absorption in optical wavelengths. A discussion on the nature of the dust from CVF observations is also presented. The central part and the molecular ring of M31 are excellent targets for FIRST
Herschel observations in the ultracompact HII region Mon R2: Water in dense Photon-dominated regions (PDRs)
Mon R2, at a distance of 830 pc, is the only ultracompact HII region (UC HII)
where the photon-dominated region (PDR) between the ionized gas and the
molecular cloud can be resolved with Herschel. HIFI observations of the
abundant compounds 13CO, C18O, o-H2-18O, HCO+, CS, CH, and NH have been used to
derive the physical and chemical conditions in the PDR, in particular the water
abundance. The 13CO, C18O, o-H2-18O, HCO+ and CS observations are well
described assuming that the emission is coming from a dense (n=5E6 cm-3,
N(H2)>1E22 cm-2) layer of molecular gas around the UC HII. Based on our
o-H2-18O observations, we estimate an o-H2O abundance of ~2E-8. This is the
average ortho-water abundance in the PDR. Additional H2-18O and/or water lines
are required to derive the water abundance profile. A lower density envelope
(n~1E5 cm-3, N(H2)=2-5E22 cm-2) is responsible for the absorption in the NH
1_1-0_2 line. The emission of the CH ground state triplet is coming from both
regions with a complex and self-absorbed profile in the main component. The
radiative transfer modeling shows that the 13CO and HCO+ line profiles are
consistent with an expansion of the molecular gas with a velocity law, v_e =0.5
x (r/Rout)^{-1} km/s, although the expansion velocity is poorly constrained by
the observations presented here.Comment: 4 pages, 5 figure
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