9,839 research outputs found
Detecting paired and counterflow superfluidity via dipole oscillations
We suggest an experimentally feasible procedure to observe paired and
counterflow superfluidity in ultra-cold atom systems. We study the time
evolution of one-dimensional mixtures of bosonic atoms in an optical lattice
following an abrupt displacement of an additional weak confining potential. We
find that the dynamic responses of the paired superfluid phase for attractive
inter-species interactions and the counterflow superfluid phase for repulsive
interactions are qualitatively distinct and reflect the quasi long-range order
that characterizes these states. These findings suggest a clear experimental
procedure to detect these phases, and give an intuitive insight into their
dynamics.Comment: 4 pages,5 figure
Retrieving Nuclear Information from Protons Propagating through A Thick Target
The multiple scattering of high-energy particles in a thick target is
fromulated in an impact parameter representation. A formalism similar but not
identical to that of Moliere is obtained. We show that calculations of particle
beam broadening due to multiple Coulomb scattering alone can be given in closed
form. The focus of this study is on whether or not the broadening of the
Coulomb angular distribution prevents the retrieval of nuclear-interaction
information from mesauring the angular distributions of charged partiles
scattered from a thick target. For this purpose, we study multiple scatterings
with both the nuclear and Coulomb interactions included and we do not make a
small-angle expansion. Condition for retrieving nuclear infomration from
high-energy protons propagating through a block of material are obtained.Comment: 29 pages, 13 figure
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Investigation of discrepancies in satellite rainfall estimates over Ethiopia
Tropical Applications of Meteorology Using Satellite and Ground-Based Observations (TAMSAT) rainfall estimates are used extensively across Africa for operational rainfall monitoring and food security applications; thus, regional evaluations of TAMSAT are essential to ensure its reliability. This study assesses the performance of TAMSAT rainfall estimates, along with the African Rainfall Climatology (ARC), version 2; the Tropical Rainfall Measuring Mission (TRMM) 3B42 product; and the Climate Prediction Center morphing technique (CMORPH), against a dense rain gauge network over a mountainous region of Ethiopia. Overall, TAMSAT exhibits good skill in detecting rainy events but underestimates rainfall amount, while ARC underestimates both rainfall amount and rainy event frequency. Meanwhile, TRMM consistently performs best in detecting rainy events and capturing the mean rainfall and seasonal variability, while CMORPH tends to overdetect rainy events. Moreover, the mean difference in daily rainfall between the products and rain gauges shows increasing underestimation with increasing elevation. However, the distribution in satellite–gauge differences demon- strates that although 75% of retrievals underestimate rainfall, up to 25% overestimate rainfall over all eleva- tions. Case studies using high-resolution simulations suggest underestimation in the satellite algorithms is likely due to shallow convection with warm cloud-top temperatures in addition to beam-filling effects in microwave- based retrievals from localized convective cells. The overestimation by IR-based algorithms is attributed to nonraining cirrus with cold cloud-top temperatures. These results stress the importance of understanding re- gional precipitation systems causing uncertainties in satellite rainfall estimates with a view toward using this knowledge to improve rainfall algorithms
Intervention Now To Eliminate Repeat Unintended Pregnancy in Teenagers (INTERUPT): a systematic review of intervention effectiveness and cost-effectiveness, qualitative and realist synthesis of implementation factors and user engagement
Background The UK has the highest rate of teenage pregnancies in Western Europe, a fifth are repeat pregnancies. Unintended conceptions can result in emotional, psychological and educational harm to teenage girls, often with enduring implications for their life chances. Babies of teenage mothers have increased mortality in their first year and increased risk of poverty, educational underachievement and unemployment later in life, with associated societal costs.
Methods and analysis We will conduct a streamed, mixed-methods systematic review to find and evaluate interventions designed to reduce repeat unintended teen pregnancies.
Our aims are to identify Who is at greater risk of repeat unintended pregnancies? Which interventions are effective, cost-effective, how they work, in what setting and for whom? What are the barriers and facilitators to intervention uptake? Traditional electronic database searches will be augmented by targeted searches for evidence ‘clusters’ and guided by an advisory group of experts and stakeholders. To address the topic's inherent complexities, we will use a highly structured, innovative and iterative approach combining methodological techniques tailored to each stream of evidence. Quantitative data will be synthesised with reference to Cochrane guidelines for public health interventions. Qualitative evidence addressing facilitators and barriers to the uptake of interventions, experience and acceptability of interventions will be synthesised thematically. We will apply the principles of realist synthesis to uncover theories and mechanisms underpinning interventions. We will conduct an integration and overarching narrative of findings authenticated by client group feedback.
Ethics and dissemination We will publish the complete review in ‘Health Technology Assessment’ and sections in specialist peer-reviewed journals. We will present at national and international conferences in the fields of public health, reproductive medicine and review methodology. Findings will be fed back to service users and practitioners via workshops run by the partner collaborators
Mesoscopic Effects in Quantum Phases of Ultracold Quantum Gases in Optical Lattices
We present a wide array of quantum measures on numerical solutions of 1D
Bose- and Fermi-Hubbard Hamiltonians for finite-size systems with open boundary
conditions. Finite size effects are highly relevant to ultracold quantum gases
in optical lattices, where an external trap creates smaller effective regions
in the form of the celebrated "wedding cake" structure and the local density
approximation is often not applicable. Specifically, for the Bose-Hubbard
Hamiltonian we calculate number, quantum depletion, local von-Neumann entropy,
generalized entanglement or Q-measure, fidelity, and fidelity susceptibility;
for the Fermi-Hubbard Hamiltonian we also calculate the pairing correlations,
magnetization, charge-density correlations, and antiferromagnetic structure
factor. Our numerical method is imaginary time propagation via time-evolving
block decimation. As part of our study we provide a careful comparison of
canonical vs. grand canonical ensembles and Gutzwiller vs. entangled
simulations. The most striking effect of finite size occurs for bosons: we
observe a strong blurring of the tips of the Mott lobes accompanied by higher
depletion, and show how the location of the first Mott lobe tip approaches the
thermodynamic value as a function of system size.Comment: 13 pages, 10 figure
Usage of and attitudes about green tea extract and Epigallocathechin-3-gallate (EGCG) as a therapy in individuals with Down syndrome
Objective
Usage of and views concerning alternative therapies in the DS community are not well documented. Some positive effects of green tea extracts (GTE) containing Epigallocathechin-3-gallate (EGCG) have been reported in individuals with DS and DS mouse models, but minimal improvements or detrimental effects of pure EGCG treatment have been reported in DS mouse models. Given the uncertainty about the effectiveness of these supplements, the goal of this study was to determine the relative prevalence of and attitudes about GTE/EGCG treatments among DS caregivers.
Methods
An anonymous survey about attitudes and usage of GTE/EGCG in individuals with DS was completed by caregivers of these individuals.
Results
GTE/EGCG treatment was provided by 18% of responding caregivers who were mostly younger, highly educated, and utilized scientific sources and other parents to influence their decision to use GTE/EGCG. Individuals with DS who received GTE/EGCG were characterized as less severely disabled. Most caregivers who did not give GTE/EGCG reported concerns about potential side effects and lack of effectiveness. Few caregivers consulted with medical providers about GTE/EGCG usage.
Conclusions
These results demonstrate a need for communication between caregivers, medical providers, and scientists about potential benefits and risks for adverse effects of GTE, EGCG, and other nutritional supplements in individuals with DS
A Bow Shock Nebula Around a Compact X-Ray Source in the Supernova Remnant IC443
We present spectra and high resolution images of the hard X-ray feature along
the southern edge of the supernova remnant IC443. Data from the Chandra X-ray
Observatory reveal a comet-shaped nebula of hard emission, which contains a
softer point source at its apex. We also present 20cm, 6cm, and 3.5cm images
from the Very Large Array that clearly show the cometary nebula. Based on the
radio and X-ray morphology and spectrum, and the radio polarization properties,
we argue that this object is a synchrotron nebula powered by the compact source
that is physically associated with IC443. The spectrum of the soft point source
is adequately but not uniquely fit by a black body model (kT=0.71 +/- 0.08 keV,
L=(6.5 +/- 0.9) * 10^31 erg/s). The cometary morphology of the nebula is the
result of the supersonic motion of the neutron star (V_NS=250 +/- 50 km/s),
which causes the relativistic wind of the pulsar to terminate in a bow shock
and trail behind as a synchrotron tail. This velocity is consistent with an age
of 30,000 years for the SNR and its associated neutron star.Comment: 9 pages, 5 figures, accepted for publication in the ApJ Letter
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