182 research outputs found
Sleep problems for children with autism and caregiver spillover effects
Sleep problems in children with autism spectrum disorders (ASD) are under-recognized and under-treated. Identifying treatment value accounting for health effects on family members (spillovers) could improve the perceived cost-effectiveness of interventions to improve child sleep habits. A prospective cohort study (N = 224) was conducted with registry and postal survey data completed by the primary caregiver.Wecalculated quality of life outcomes for the child and the primary caregiver associated with treatments to improve sleep in the child based on prior clinical trials. Predicted treatment effects for melatonin and behavioral interventions were similar in magnitude for the child and for the caregiver. Accounting for caregiver spillover effects associated with treatments for the child with ASD increases treatment benefits and improves cost-effectiveness profiles
Design and operation of automated ice-tethered profilers for real-time seawater observations in the polar oceans
An automated, easily-deployed Ice-Tethered Profiler (ITP) has been developed for deployment on perennial sea ice in polar oceans to
measure changes in upper ocean temperature and salinity in all seasons. The ITP system consists of three components: a surface
instrument that sits atop an ice floe, a weighted, plastic-jacketed wire-rope tether of arbitrary length (up to 800 m) suspended from the
surface instrument, and an instrumented underwater unit that profiles up and down the wire tether. The profiling underwater unit is
similar in shape and dimension to an ARGO float except that the float's variable-buoyancy system is replaced with a traction drive unit.
Deployment of ITPs may be conducted either from ice caps or icebreakers, utilizing a self contained tripod/winch system that requires no
power. Careful selection of an appropriate multiyear ice floe is needed to prolong the lifetime of the system (up to 3 years depending on
the profiling schedule). Shortly after deployment, each ITP begins profiling the water column at its programmed sampling interval. After
each acquired temperature and salinity profile, the underwater unit (PROCON) transfers the data and engineering files using an inductive
modem to the surface controller (SURFCON). SURFCON also accumulates battery voltages, buoy temperature, and locations from GPS at
specified intervals in status files, and queues that information for transmission at the start of each new day. At frequent intervals, an
Iridium satellite transceiver in the surface package calls and transmits queued status and CTD data files onto a WHOI logger computer,
which are subsequently processed and displayed in near-real time at http://www.whoi.edu/itp. In 2004 and 2005, three ITP prototypes
were deployed in the Arctic Ocean. Each system was programmed with accelerated sampling schedules of multiple one-way traverses per
day between 10 and 750-760 m depth in order to quickly evaluate endurance and component fatigue. Two of the ITPs are continuing to
function after more than 10 months and 1200 profiles. Larger motor currents are observed at times of fast ice floe motion when larger
wire angles develop and drag forces on the profiler are increased. The CTD profile data so far obtained document interesting spatial
variations in the major water masses of the Beaufort Gyre, show the double-diffusive thermohaline staircase that lies above the warm,
salty Atlantic layer, and many mesoscale eddys. Deployed together with CRREL Ice Mass Balance (IMB) buoys, these ITP systems also
operate as part of an Ice Based Observatory (IBO). Data returned from an array of IBOs within an Arctic Observing Network will provide
valuable real time observations, support studies of ocean processes, and facilitate numerical model initialization and validation.Funding was provided by the National Science Foundation under Contract Nos. OCE-0324233 and ARC-0519899
The Cold Peace: Russo-Western Relations as a Mimetic Cold War
In 1989â1991 the geo-ideological contestation between two blocs was swept away, together with the ideology of civil war and its concomitant Cold War played out on the larger stage. Paradoxically, while the domestic sources of Cold War confrontation have been transcended, its external manifestations remain in the form of a âlegacyâ geopolitical contest between the dominant hegemonic power (the United States) and a number of potential rising great powers, of which Russia is one. The post-revolutionary era is thus one of a âcold peaceâ. A cold peace is a mimetic cold war. In other words, while a cold war accepts the logic of conflict in the international system and between certain protagonists in particular, a cold peace reproduces the behavioural patterns of a cold war but suppresses acceptance of the logic of behaviour. A cold peace is accompanied by a singular stress on notions of victimhood for some and undigested and bitter victory for others. The perceived victim status of one set of actors provides the seedbed for renewed conflict, while the âvictoryâ of the others cannot be consolidated in some sort of relatively unchallenged post-conflict order. The âuniversalismâ of the victors is now challenged by Russia's neo-revisionist policy, including not so much the defence of Westphalian notions of sovereignty but the espousal of an international system with room for multiple systems (the Schmittean pluriverse)
Bright Strongly Lensed Galaxies at Redshift z~ 6-7 behind the Clusters Abell 1703 and CL0024+161
We report on the discovery of three bright, strongly-lensed objects behind
Abell 1703 and CL0024+16 from a dropout search over 25 square arcminutes of
deep NICMOS data, with deep ACS optical coverage. They are undetected in the
deep ACS images below 8500 A and have clear detections in the J and H bands.
Fits to the ACS, NICMOS and IRAC data yield robust photometric redshifts in the
range z~6-7 and largely rule out the possibility that they are low-redshift
interlopers. All three objects are extended, and resolved into a pair of bright
knots. The bright i-band dropout in Abell 1703 has an H-band AB magnitude of
23.9, which makes it one of the brightest known galaxy candidates at z>5.5. Our
model fits suggest a young, massive galaxy only ~ 60 million years old with a
mass of ~ 1E10 solar mass. The dropout galaxy candidates behind CL0024+16 are
separated by 2.5" (~ 2 kpc in the source plane), and have H-band AB magnitudes
of 25.0 and 25.6. Lensing models of CL0024+16 suggest that the objects have
comparable intrinsic magnitudes of AB ~ 27.3, approximately one magnitude
fainter than L* at z~6.5. Their similar redshifts, spectral energy
distribution, and luminosities, coupled with their very close proximity on the
sky, suggest that they are spatially associated, and plausibly are physically
bound. Combining this sample with two previously reported, similarly magnified
galaxy candidates at z~6-8, we find that complex systems with dual nuclei may
be a common feature of high-redshift galaxies.Comment: 34 pages, 9 figure
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Modeling Transport in Gas Chromatography Columns for the Micro-ChemLab
The gas chromatography (GC) column is a critical component in the microsystem for chemical detection ({mu}ChemLab{trademark}) being developed at Sandia. The goal is to etch a meter-long GC column onto a 1-cm{sup 2} silicon chip while maintaining good chromatographic performance. Our design strategy is to use a modeling and simulation approach. We have developed an analytical tool that models the transport and surface interaction process to achieve an optimized design of the GC column. This analytical tool has a flow module and a separation module. The flow module considers both the compressibility and slip flow effects that may significantly influence the gas transport in a long and narrow column. The separation module models analyte transport and physico-chemical interaction with the coated surface in the GC column. It predicts the column efficiency and performance. Results of our analysis will be presented in this paper. In addition to the analytical tool, we have also developed a time-dependent adsorption/desorption model and incorporated this model into a computational fluid dynamics (CFD) code to simulate analyte transport and separation process in GC columns. CFD simulations can capture the complex three-dimensional flow and transport dynamics, whereas the analytical tool cannot. Different column geometries have been studied, and results will be presented in this paper. Overall we have demonstrated that the modeling and simulation approach can guide the design of the GC column and will reduce the number of iterations in the device development
Cluster Lenses
Clusters of galaxies are the most recently assembled, massive, bound
structures in the Universe. As predicted by General Relativity, given their
masses, clusters strongly deform space-time in their vicinity. Clusters act as
some of the most powerful gravitational lenses in the Universe. Light rays
traversing through clusters from distant sources are hence deflected, and the
resulting images of these distant objects therefore appear distorted and
magnified. Lensing by clusters occurs in two regimes, each with unique
observational signatures. The strong lensing regime is characterized by effects
readily seen by eye, namely, the production of giant arcs, multiple-images, and
arclets. The weak lensing regime is characterized by small deformations in the
shapes of background galaxies only detectable statistically. Cluster lenses
have been exploited successfully to address several important current questions
in cosmology: (i) the study of the lens(es) - understanding cluster mass
distributions and issues pertaining to cluster formation and evolution, as well
as constraining the nature of dark matter; (ii) the study of the lensed objects
- probing the properties of the background lensed galaxy population - which is
statistically at higher redshifts and of lower intrinsic luminosity thus
enabling the probing of galaxy formation at the earliest times right up to the
Dark Ages; and (iii) the study of the geometry of the Universe - as the
strength of lensing depends on the ratios of angular diameter distances between
the lens, source and observer, lens deflections are sensitive to the value of
cosmological parameters and offer a powerful geometric tool to probe Dark
Energy. In this review, we present the basics of cluster lensing and provide a
current status report of the field.Comment: About 120 pages - Published in Open Access at:
http://www.springerlink.com/content/j183018170485723/ . arXiv admin note:
text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author
Gravitational Lensing
Gravitational lensing has developed into one of the most powerful tools for
the analysis of the dark universe. This review summarises the theory of
gravitational lensing, its main current applications and representative results
achieved so far. It has two parts. In the first, starting from the equation of
geodesic deviation, the equations of thin and extended gravitational lensing
are derived. In the second, gravitational lensing by stars and planets,
galaxies, galaxy clusters and large-scale structures is discussed and
summarised.Comment: Invited review article to appear in Classical and Quantum Gravity, 85
pages, 15 figure
Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens
Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift zâ=â1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than Ă2,000. A separate image, detected briefly 0.26âł from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of âł3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the starsâ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two imagesâ long-term brightness ratio
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