21,443 research outputs found
Optical constants of uranium plasma Final report
Thermodynamic and optical properties of uranium plasma in proposed gaseous core nuclear rocket
Entropic Origin of Pseudogap Physics and a Mott-Slater Transition in Cuprates
We propose a new approach to understand the origin of the pseudogap in the
cuprates, in terms of bosonic entropy. The near-simultaneous softening of a
large number of different -bosons yields an extended range of short-range
order, wherein the growth of magnetic correlations with decreasing temperature
is anomalously slow. These entropic effects cause the spectral weight
associated with the Van Hove singularity (VHS) to shift rapidly and nearly
linearly toward half filling at higher , consistent with a picture of the
VHS driving the pseudogap transition at a temperature . As a
byproduct, we develop an order-parameter classification scheme that predicts
supertransitions between families of order parameters. As one example, we find
that by tuning the hopping parameters, it is possible to drive the cuprates
across a {\it transition between Mott and Slater physics}, where a
spin-frustrated state emerges at the crossover.Comment: 24 pgs, 15 figs + Supp. Material [6pgs, 3 figs]. Major revision of
arXiv:1505.0477
Characterization of Thin Film Materials using SCAN meta-GGA, an Accurate Nonempirical Density Functional
We discuss self-consistently obtained ground-state electronic properties of
monolayers of graphene and a number of beyond graphene compounds, including
films of transition-metal dichalcogenides (TMDs), using the recently proposed
strongly constrained and appropriately normed (SCAN) meta-generalized gradient
approximation (meta-GGA) to the density functional theory. The SCAN meta-GGA
results are compared with those based on the local density approximation (LDA)
as well as the generalized gradient approximation (GGA). As expected, the GGA
yields expanded lattices and softened bonds in relation to the LDA, but the
SCAN meta-GGA systematically improves the agreement with experiment. Our study
suggests the efficacy of the SCAN functional for accurate modeling of
electronic structures of layered materials in high-throughput calculations more
generally
What impact did a Paediatric Early Warning system have on emergency admissions to the paediatric intensive care unit? An observational cohort study
Summary
The ideology underpinning Paediatric Early Warning systems (PEWs) is that earlier recognition of deteriorating in-patients would improve clinical outcomes.
Objective
To explore how the introduction of PEWs at a tertiary children's hospital affects emergency admissions to the Paediatric Intensive Care Unit (PICU) and the impact on service delivery. To compare ‘in-house’ emergency admissions to PICU with ‘external’ admissions transferred from District General Hospitals (without PEWs).
Method
A before-and-after observational study August 2005–July 2006 (pre), August 2006–July 2007 (post) implementation of PEWs at the tertiary children's hospital.
Results
The median Paediatric Index of Mortality (PIM2) reduced; 0.44 vs 0.60 (p < 0.001). Fewer admissions required invasive ventilation 62.7% vs 75.2% (p = 0.015) for a shorter median duration; four to two days. The median length of PICU stay reduced; five to three days (p = 0.002). There was a non-significant reduction in mortality (p = 0.47). There was no comparable improvement in outcome seen in external emergency admissions to PICU. A 39% reduction in emergency admission total beds days reduced cancellation of major elective surgical cases and refusal of external PICU referrals.
Conclusions
Following introduction of PEWs at a tertiary children's hospital PIM2 was reduced, patients required less PICU interventions and had a shorter length of stay. PICU service delivery improved
Dry matter yields and quality of organic lupin/cereal mixtures for wholecrop forage
In view of climate change predictions and the general desirability of increasing the amount of home grown protein, a case exists for the investigation of lupins and lupin/cereal bicrop combinations as wholecrop forage on organic farms. A replicated randomised block trial is described which took place at the Royal Agricultural College, Cirencester, in 2005. This involved spring sown blue, white and yellow lupins, millet, wheat and triticale and lupin/cereal bi-crops. Data for dry matter yields for wholecrop silage, crude protein, MAD fi bre content and estimated ME, are presented for a single harvest. It is concluded that white lupins and white lupin bi-crops with spring wheat or triticale offer the best prospects for a viable wholecrop forage crop in an organic situation
A Search for New Physics with the BEACON Mission
The primary objective of the Beyond Einstein Advanced Coherent Optical
Network (BEACON) mission is a search for new physics beyond general relativity
by measuring the curvature of relativistic space-time around Earth. This
curvature is characterized by the Eddington parameter \gamma -- the most
fundamental relativistic gravity parameter and a direct measure for the
presence of new physical interactions. BEACON will achieve an accuracy of 1 x
10^{-9} in measuring the parameter \gamma, thereby going a factor of 30,000
beyond the present best result involving the Cassini spacecraft. Secondary
mission objectives include: (i) a direct measurement of the "frame-dragging"
and geodetic precessions in the Earth's rotational gravitomagnetic field, to
0.05% and 0.03% accuracy correspondingly, (ii) first measurement of gravity's
non-linear effects on light and corresponding 2nd order spatial metric's
effects to 0.01% accuracy. BEACON will lead to robust advances in tests of
fundamental physics -- this mission could discover a violation or extension of
general relativity and/or reveal the presence of an additional long range
interaction in physics. BEACON will provide crucial information to separate
modern scalar-tensor theories of gravity from general relativity, probe
possible ways for gravity quantization, and test modern theories of
cosmological evolution.Comment: 8 pages, 2 figures, 2 table
Travelling waves in a tissue interaction model for skin pattern formation
Tissue interaction plays a major role in many morphogenetic processes, particularly those associated with skin organ primordia. We examine travelling wave solutions in a tissue interaction model for skin pattern formation which is firmly based on the known biology. From a phase space analysis we conjecture the existence of travelling waves with specific wave speeds. Subsequently, analytical approximations to the wave profiles are derived using perturbation methods. We then show numerically that such travelling wave solutions do exist and that they are in good agreement with our analytical results. Finally, the biological implications of our analysis are discussed
Pseudo-Goldstone Boson Effects in Top-Antitop Productions at High Energy Hadron Colliders and Testing Technicolor Models
We study the top quark pair production process p+p(anti-p)-->top+antitop in
various kinds of technicolor (TC) models at the Fermilab Tevatron Run II and
the CERN LHC. The s-channel neutral pseudo-Goldstone bosons (PGB's) contribute
dominately to the production amplitudes from its coupling to the gluons through
the triangle loops of techniquarks and the top quark. Cross sections in
different TC models with s-channel PGB contributions are calculated. It is
shown that the PGB effects can be experimentally tested and different TC models
under consideration can be distinguished at the LHC. Therefore, the
p+p-->top+antitop process at the LHC provides feasible tests of the TC models.Comment: 10 pages in RevTex and 4 PS-files for the figures. Paramemter range
is changed, and some references are added. Version for publication in Phys.
Rev.
Composite Scalars at LEP: Constraining Technicolor Theories
LEPI and LEPII data can be used to constrain technicolor models with light,
neutral pseudo-Nambu-Goldstone bosons, Pa. We use published limits on branching
ratios and cross sections for final states with photons, large missing energy,
jet pairs, and b bbar pairs to constrain the anomalous Pa Z0 Z0, Pa Z0 photon,
and Pa photon photon couplings. From these results, we derive bounds on the
size of the technicolor gauge group and the number of technifermion doublets in
models such as Low-scale Technicolor.Comment: 27 pages (including title page), 15 figures, 6 tables. version 2: In
addressing PRD referee comments, we have significantly expanded our
manuscript, to include detailed discussion of limits from LEP II data, as
well as expanding the number or specific models to which we apply our
results. As a result, we have changed the title from "Z0 decays to composite
scalars: constraining technicolor theories
- …