220 research outputs found
Can inflationary models of cosmic perturbations evade the secondary oscillation test?
We consider the consequences of an observed Cosmic Microwave Background (CMB)
temperature anisotropy spectrum containing no secondary oscillations. While
such a spectrum is generally considered to be a robust signature of active
structure formation, we show that such a spectrum {\em can} be produced by
(very unusual) inflationary models or other passive evolution models. However,
we show that for all these passive models the characteristic oscillations would
show up in other observable spectra. Our work shows that when CMB polarization
and matter power spectra are taken into account secondary oscillations are
indeed a signature of even these very exotic passive models. We construct a
measure of the observability of secondary oscillations in a given experiment,
and show that even with foregrounds both the MAP and \pk satellites should be
able to distinguish between models with and without oscillations. Thus we
conclude that inflationary and other passive models can {\em not} evade the
secondary oscillation test.Comment: Final version accepted for publication in PRD. Minor improvements
have been made to the discussion and new data has been included. The
conclusions are unchagne
Human airway smooth muscle maintain in situ cell orientation and phenotype when cultured on aligned electrospun scaffolds
Human airway smooth muscle (HASM) contraction plays a central role in regulating airway resistance in both healthy and asthmatic bronchioles. In vitro studies that investigate the intricate mechanisms that regulate this contractile process are predominantly conducted on tissue culture plastic, a rigid, 2D geometry, unlike the 3D microenvironment smooth muscle cells are exposed to in situ. It is increasingly apparent that cellular characteristics and responses are altered between cells cultured on 2D substrates compared with 3D topographies. Electrospinning is an attractive method to produce 3D topographies for cell culturing as the fibers produced have dimensions within the nanometer range, similar to cells' natural environment. We have developed an electrospun scaffold using the nondegradable, nontoxic, polymer polyethylene terephthalate (PET) composed of uniaxially orientated nanofibers and have evaluated this topography's effect on HASM cell adhesion, alignment, and morphology. The fibers orientation provided contact guidance enabling the formation of fully aligned sheets of smooth muscle. Moreover, smooth muscle cells cultured on the scaffold present an elongated cell phenotype with altered contractile protein levels and distribution. HASM cells cultured on this scaffold responded to the bronchoconstrictor bradykinin. The platform presented provides a novel in vitro model that promotes airway smooth muscle cell development toward a more in vivo-like phenotype while providing topological cues to ensure full cell alignment
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Emotional health in adolescents with and without a history of specific language impairment (SLI)
Objective:  This study examined the emotional health of adolescents with and without specific language impairment (SLI).
Method:  One hundred and thirty-nine adolescents with a history of SLI (15;10 years) and a peer group of 124 adolescents with normal language development (NLD) (15;11 years) participated, who were in their final year of compulsory schooling. The risk of emotional difficulties was assessed using the Moods and Feelings Questionnaire (MFQ) and the Child Manifest Anxiety Scale-R (CMAS-R). Comprehensive language and cognition data were available for all participants (NLD and SLI) concurrently and also longitudinally for those with SLI.
Results:  A clear increased risk of emotional health symptoms was found for the SLI group on both self- and parental-report. Girls scored less favourably than boys when groups were combined, but these were due to the effect of the NLD group, with no gender differences found in the SLI group. Direct links with language and cognition were not obvious. Instead, more diffuse factors such as family history of emotional health difficulties may warrant further investigation.
Conclusion:  There is a marked higher rate of anxiety and depression symptoms in adolescents with SLI. However, these do not appear to be a direct result of impoverished communicative experiences
The Primordial Inflation Explorer (PIXIE): A Nulling Polarimeter for Cosmic Microwave Background Observations
The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to
measure the gravity-wave signature of primordial inflation through its
distinctive imprint on the linear polarization of the cosmic microwave
background. The instrument consists of a polarizing Michelson interferometer
configured as a nulling polarimeter to measure the difference spectrum between
orthogonal linear polarizations from two co-aligned beams. Either input can
view the sky or a temperature-controlled absolute reference blackbody
calibrator. PIXIE will map the absolute intensity and linear polarization
(Stokes I, Q, and U parameters) over the full sky in 400 spectral channels
spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 um
wavelength). Multi-moded optics provide background-limited sensitivity using
only 4 detectors, while the highly symmetric design and multiple signal
modulations provide robust rejection of potential systematic errors. The
principal science goal is the detection and characterization of linear
polarization from an inflationary epoch in the early universe, with
tensor-to-scalar ratio r < 10^{-3} at 5 standard deviations. The rich PIXIE
data set will also constrain physical processes ranging from Big Bang cosmology
to the nature of the first stars to physical conditions within the interstellar
medium of the Galaxy.Comment: 37 pages including 17 figures. Submitted to the Journal of Cosmology
and Astroparticle Physic
Near-threshold measurement of the 4He(g,n) reaction
A near-threshold 4He(g,n) cross-section measurement has been performed at
MAX-lab. Tagged photons from 23 < Eg < 42 MeV were directed toward a liquid 4He
target, and neutrons were detected by time-of-flight in two liquid-scintillator
arrays. Seven-point angular distributions were measured for eight photon
energies. The results are compared to experimental data measured at comparable
energies and Recoil-Corrected Continuum Shell Model, Resonating Group Method,
and recent Hyperspherical-Harmonic Expansion calculations. The angle-integrated
cross-section data is peaked at a photon energy of about 28 MeV, in
disagreement with the value recommended by Calarco, Berman, and Donnelly in
1983.Comment: 10 pages, 3 figures, some revisions, submitted to Physics Letters
Electronic structure, phase stability and chemical bonding in ThAl and ThAlH
We present the results of theoretical investigation on the electronic
structure, bonding nature and ground state properties of ThAl and
ThAlH using generalized-gradient-corrected first-principles
full-potential density-functional calculations. ThAlH has been reported
to violate the "2 \AA rule" of H-H separation in hydrides. From our total
energy as well as force-minimization calculations, we found a shortest H-H
separation of 1.95 {\AA} in accordance with recent high resolution powder
neutron diffraction experiments. When the ThAl matrix is hydrogenated, the
volume expansion is highly anisotropic, which is quite opposite to other
hydrides having the same crystal structure. The bonding nature of these
materials are analyzed from the density of states, crystal-orbital Hamiltonian
population and valence-charge-density analyses. Our calculation predicts
different nature of bonding for the H atoms along and . The strongest
bonding in ThAlH is between Th and H along which form dumb-bell
shaped H-Th-H subunits. Due to this strong covalent interaction there is very
small amount of electrons present between H atoms along which makes
repulsive interaction between the H atoms smaller and this is the precise
reason why the 2 {\AA} rule is violated. The large difference in the
interatomic distances between the interstitial region where one can accommodate
H in the and planes along with the strong covalent interaction
between Th and H are the main reasons for highly anisotropic volume expansion
on hydrogenation of ThAl.Comment: 14 pages, 9 figure
Self-efficacy, habit strength, health locus of control and response to the personalised nutrition Food4Me intervention study
YesPurpose – Randomised controlled trials identify causal links between variables but not why an outcome has
occurred. This analysis sought to determine how psychological factors assessed at baseline influenced
response to personalised nutrition.
Design/methodology/approach – Web-based, randomised, controlled trial (RCT) was conducted across
seven European countries. Volunteers, both male and female, aged over 18 years were randomised to either a
non-personalised (control) or a personalised (treatment) dietary advice condition. Linear mixed model analysis
with fixed effects was used to compare associations between internal and external health locus of control
(HLoC), nutrition self-efficacy (NS-E) and self-report habit index (S-RHI) at baseline (N 5 1444), with healthy
eating index (HEI) and Mediterranean diet index (MDI) scores between conditions post-intervention (N 5 763).
Findings – An increase in MDI scores was observed between baseline and six months in the treatment group
which was associated with higher NS-E (pEU FP7 Project “Personalised nutrition: an integrated analysis of opportunities and challenges” (Contract No. KBBE. 2010.2.3–02, Project No. 265494
Measurement and simulation of the neutron response of the Nordball liquid scintillator array
The response of the liquid scintillator array Nordball to neutrons in the
energy range 1.5 < T_n < 10 MeV has been measured by time of flight using a
252Cf fission source. Fission fragments were detected by means of a thin-film
plastic scintillator. The measured differential and integral neutron detection
efficiencies agree well with predictions of a Monte Carlo simulation of the
detector which models geometry accurately and incorporates the measured,
non-linear proton light output as a function of energy. The ability of the
model to provide systematic corrections to photoneutron cross sections,
measured by Nordball at low energy, is tested in a measurement of the two-body
deuteron photodisintegration cross section in the range E_gamma=14-18 MeV.
After correction the present 2H(gamma,n)p measurements agree well with a
published evaluation of the large body of 2H(gamma,p)n data.Comment: 20 pages 10 figures, submitted Nucl. Instr. Meth.
Atmosphere Revitalization Technology Development for Crewed Space Exploration
As space exploration objectives extend human presence beyond low Earth orbit, the solutions to technological challenges presented by supporting human life in the hostile space environment must build upon experience gained during past and present crewed space exploration programs. These programs and the cabin atmosphere revitalization process technologies and systems developed for them represent the National Aeronautics and Space Administration s (NASA) past and present operational knowledge base for maintaining a safe, comfortable environment for the crew. The contributions of these programs to the NASA s technological and operational working knowledge base as well as key strengths and weaknesses to be overcome are discussed. Areas for technological development to address challenges inherent with the Vision for Space Exploration (VSE) are presented and a plan for their development employing unit operations principles is summarize
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