1,813 research outputs found
A comparative analysis of rawinsonde and NIMBUS 6 and TIROS N satellite profile data
Comparisons are made between rawinsonde and satellite profiles in seven areas for a wide range of surface and weather conditions. Variables considered include temperature, dewpoint temperature, thickness, precipitable water, lapse rate of temperature, stability, geopotential height, mixing ratio, wind direction, wind speed, and kinematic parameters, including vorticity and the advection of vorticity and temperature. In addition, comparisons are made in the form of cross sections and synoptic fields for selected variables. Sounding data from the NIMBUS 6 and TIROS N satellites were used. Geostrophic wind computed from smoothed geopotential heights provided large scale flow patterns that agreed well with the rawinsonde wind fields. Surface wind patterns as well as magnitudes computed by use of the log law to extrapolate wind to a height of 10 m agreed with observations. Results of this study demonstrate rather conclusively that satellite profile data can be used to determine characteristics of large scale systems but that small scale features, such as frontal zones, cannot yet be resolved
The Mental and Physical Health of Mothers of Children with Special Health Care Needs in the United States
OBJECTIVE: To determine the prevalence of poor mental and physical health among mothers of children with special health care needs (CSHCN) and to determine the association between maternal health and the child\u27s number of special health care needs (SHCN) and severity of ability limitation.
METHODS: We used the combined 2016-2018 National Survey of Children\u27s Health Dataset of 102,341 children ages 0-17 including 23,280 CSHCN. We used regression models to examine the associations of a child\u27s number of SHCN and ability limitations with maternal health.
RESULTS: Twice as many mothers of CSHCN had poor mental and physical health compared to non-CSHCN (mental 10.3% vs. 4.0%, p \u3c .001; physical 11.9% vs 5.0%, p \u3c .001). In regression models, increased number of SHCN and severity of activity limitations were associated with significantly increased odds of poor maternal health.
CONCLUSIONS FOR PRACTICE: Mothers of CSHCN have worse health compared to mothers of non-CSHCN, especially those who experience social disadvantage and those with children with complex SHCN or severe ability limitations. Interventions to improve the health of these particularly vulnerable caregivers of CSHCN are warranted
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Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems
In many regions, three dimensional characterization of the groundwater regime is limited by coarse well spacing or borehole lithologic logs of low quality. However, regulatory requirements for drinking water or site remediation may require collection of extensive chemical and water quality data from existing wells. Similarly, for wells installed in the distant past, lithologic logs may not be available, but the wells can be sampled for chemical and isotopic constituents. In these situations, a thorough analysis of trends in chemical and isotopic constituents can be a key component in characterizing the regional groundwater system. On a basin or subbasin scale, especially in areas of intensive groundwater management where artificial recharge is important, introduction of an extrinsic tracer can provide a robust picture of groundwater flow. Dissolved gases are particularly good tracers since a large volume of water can be tagged, there are no real or perceived health risks associated with the tracer, and a very large dynamic range allows detection of a small amount of tagged water in well discharge. Recent applications of the application of extrinsic tracers, used in concert with intrinsic chemical and isotopic tracers, demonstrate the power of chemical analyses in interpreting regional subsurface flow regimes
Historical changes in the phenology of British Odonata are related to climate
Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates significantly advanced the leading edge (first quartile date) of the flight period by a mean of 1.51 ±0.060 (SEM, n=17) days per decade or 3.08±1.16 (SEM, n=17) days per degree rise in temperature when phylogeny is controlled for. This study represents the first review of changes in odonate phenology in relation to climate change. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared with terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa
First mineralogical maps of 4 Vesta
Before Dawn arrived at 4 Vesta only very low spatial resolution (~50 km) albedo and color maps were available from HST data. Also ground-based color and spectroscopic data were utilized as a first attempt to map Vesta’s mineralogical diversity [1-4]. The VIR spectrometer [5] onboard Dawn has ac-quired hyperspectral data while the FC camera [6] ob-tained multi-color data of the Vestan surface at very high spatial resolutions, allowing us to map complex geologic, morphologic units and features. We here re-port about the results obtained from a preliminary global mineralogical map of Vesta, based on data from the Survey orbit. This map is part of an iterative map-ping effort; the map is refined with each improvement in resolution
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Dissolved gas and isotopic tracers of denitrification
We present results from field studies in California (USA) where tritium-helium age dating is used in conjunction with major gases (N{sub 2}, O{sub 2}, CH{sub 4}, CO{sub 2}), noble gases (He, Ne, Ar, Kr, Xe), and stable isotopes ({sup 15}N/{sup 14}N, {sup 18}O/{sup 16}O) in order to document nitrate loading and denitrification associated with confined animal agricultural operations and septic systems. Preliminary results show that in-field extraction of the full suite of dissolved gases will be possible using a new Gas Extraction System under development to augment the current Noble Gas Mass Spectrometry and Membrane Inlet Mass Spectrometry techniques. Ascribing observed groundwater nitrate levels to specific current and past land use practices is often complicated by uncertainty in groundwater age and the degree and locus of dentrification. Groundwater age dating at dairy field sites using the {sup 3}H-{sup 3}He method indicates that the highest nitrate concentrations (150-260 mg/L-NO3) occur in waters with apparent ages of <5 yrs, whereas older waters contain excess N{sub 2} from saturated zone denitrification [1]. At a residential septic system site in Livermore, CA, waters with young apparent ages (<1 yr) proximal to leach line drainage have lower nitrate concentrations and elevated nitrate {delta}{sup 15}N and {delta}{sup 18}O values consistent with denitrification, but little evidence for excess N{sub 2}, indicating that denitrification is occurring in the unsaturated zone. Degassing of groundwater can complicate efforts to calculate travel times [2] and to quantify denitrification. Degassed groundwater underlying dairy operations is formed by two distinct mechanisms: (1) recharge of manure lagoon water affected by biogenic gas ebullition [3] and (2) saturated zone denitrification producing N{sub 2} gas above solubility in groundwater. Gas loss due to both mechanisms is evident in the concentrations of noble gases and major gases in dairy groundwater samples
First light of the VLT planet finder SPHERE. I. Detection and characterization of the sub-stellar companion GJ 758 B
GJ758 B is a brown dwarf companion to a nearby (15.76 pc) solar-type,
metal-rich (M/H = +0.2 dex) main-sequence star (G9V) that was discovered with
Subaru/HiCIAO in 2009. From previous studies, it has drawn attention as being
the coldest (~600K) companion ever directly imaged around a neighboring star.
We present new high-contrast data obtained during the commissioning of the
SPHERE instrument at the VLT. The data was obtained in Y-, J-, H-, and Ks-bands
with the dual-band imaging (DBI) mode of IRDIS, providing a broad coverage of
the full near-infrared (near-IR) range at higher contrast and better spectral
sampling than previously reported. In this new set of high-quality data, we
report the re-detection of the companion, as well as the first detection of a
new candidate closer-in to the star. We use the new 8 photometric points for an
extended comparison of GJ758 B with empirical objects and 4 families of
atmospheric models. From comparison to empirical object, we estimate a T8
spectral type, but none of the comparison object can accurately represent the
observed near-IR fluxes of GJ758 B. From comparison to atmospheric models, we
attribute a Teff = 600K 100K, but we find that no atmospheric model can
adequately fit all the fluxes of GJ758 B. The photometry of the new candidate
companion is broadly consistent with L-type objects, but a second epoch with
improved photometry is necessary to clarify its status. The new astrometry of
GJ758 B shows a significant proper motion since the last epoch. We use this
result to improve the determination of the orbital characteristics using two
fitting approaches, Least-Square Monte Carlo and Markov Chain Monte Carlo.
Finally, we analyze the sensitivity of our data to additional closer-in
companions and reject the possibility of other massive brown dwarf companions
down to 4-5 AU. [abridged]Comment: 20 pages, 15 figures. Accepted for publication in A&
First light of the VLT planet finder SPHERE. II. The physical properties and the architecture of the young systems PZ Tel and HD 1160 revisited
[Abridged] Context. The young systems PZ Tel and HD 1160, hosting known
low-mass companions, were observed during the commissioning of the new planet
finder SPHERE with several imaging and spectroscopic modes. Aims. We aim to
refine the physical properties and architecture of both systems. Methods. We
use SPHERE commissioning data and REM observations, as well as literature and
unpublished data from VLT/SINFONI, VLT/NaCo, Gemini/NICI, and Keck/NIRC2.
Results. We derive new photometry and confirm the nearly daily photometric
variability of PZ Tel A. Using literature data spanning 38 yr, we show that the
star also exhibits a long-term variability trend. The 0.63-3.8 mic SED of PZ
Tel B allows us to revise its properties: spectral type M7+/-1, Teff=2700+/-100
K, log(g)<4.5 dex, log(L/L_Sun)=-2.51+/-0.10 dex, and mass 38-72 MJ. The 1-3.8
mic SED of HD 1160 B suggests a massive brown dwarf or a low-mass star with
spectral type M5.5-7.0, Teff=3000+/-100 K, [M/H]=-0.5-0.0 dex,
log(L/L_Sun)=-2.81+/-0.10 dex, and mass 39-168 MJ. We confirm the deceleration
and high eccentricity (e>0.66) of PZ Tel B. For e<0.9, the inclination,
longitude of the ascending node, and time of periastron passage are well
constrained. The system is seen close to an edge-on geometry. We reject other
brown dwarf candidates outside 0.25" for both systems, and massive giant
planets (>4 MJ) outside 0.5" for the PZ Tel system. We also show that K1-K2
color can be used with YJH low-resolution spectra to identify young L-type
companions, provided high photometric accuracy (<0.05 mag) is achieved.
Conclusions. SPHERE opens new horizons in the study of young brown dwarfs and
giant exoplanets thanks to high-contrast imaging capabilities at optical and
near-infrared wavelengths, as well as high signal-to-noise spectroscopy in the
near-infrared from low (R~30-50) to medium resolutions (R~350).Comment: 25 pages, 23 figures, accepted for publication in A&A on Oct. 13th,
2015; version including language editing. Typo on co-author name on astroph
page corrected, manuscript unchange
Post conjunction detection of Pictoris b with VLT/SPHERE
With an orbital distance comparable to that of Saturn in the solar system,
\bpic b is the closest (semi-major axis \,9\,au) exoplanet that has
been imaged to orbit a star. Thus it offers unique opportunities for detailed
studies of its orbital, physical, and atmospheric properties, and of
disk-planet interactions. With the exception of the discovery observations in
2003 with NaCo at the Very Large Telescope (VLT), all following astrometric
measurements relative to \bpic have been obtained in the southwestern part of
the orbit, which severely limits the determination of the planet's orbital
parameters. We aimed at further constraining \bpic b orbital properties using
more data, and, in particular, data taken in the northeastern part of the
orbit.
We used SPHERE at the VLT to precisely monitor the orbital motion of beta
\bpic b since first light of the instrument in 2014. We were able to monitor
the planet until November 2016, when its angular separation became too small
(125 mas, i.e., 1.6\,au) and prevented further detection. We redetected \bpic b
on the northeast side of the disk at a separation of 139\,mas and a PA of
30 in September 2018. The planetary orbit is now well constrained.
With a semi-major axis (sma) of au (1 ), it
definitely excludes previously reported possible long orbital periods, and
excludes \bpic b as the origin of photometric variations that took place in
1981. We also refine the eccentricity and inclination of the planet. From an
instrumental point of view, these data demonstrate that it is possible to
detect, if they exist, young massive Jupiters that orbit at less than 2 au from
a star that is 20 pc away.Comment: accepted by A&
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