9,843 research outputs found
Micro-simulating child poverty in 2010 and 2020
The 2008 Pre-Budget Report (PBR) said that 'the Government will take stock of progress towards its 2010 and 2020 child poverty target in the [2009] Budget'. As background to that exercise, this paper updates our previous analysis of the prospects for child poverty in the UK in 2010-11 and 2020-21
The magnetic phase of the perovskite CaCrO studied with SR
We investigated the magnetic phase of the perovskite CaCrO by using the
muon spin relaxation technique accompanied by susceptibility measurements. A
thermal hysteresis loop is identified with a width of about 1 K at the
transition temperature. Within the time scale of the muon lifetime, a static
antiferromagnetic order is revealed with distinct multiple internal fields
which are experienced in the muon interstitial sites below the phase-transition
temperature, . Above , lattice deformations are indicated by
transverse-field muon-spin rotation and relaxation suggesting a magneto-elastic
mechanism.Comment: 5 pages, 4 figures. Accepted for publication in PR
Study of the application of hydrogen fuel to long-range subsonic transport aircraft, volume 2
The feasibility, practicability, and potential advantages/disadvantages of using liquid hydrogen as fuel in long range, subsonic transport aircraft of advanced design were studied. Both passenger and cargo-type aircraft were investigated. To provide a valid basis for comparison, conventional hydrocarbon (Jet A) fueled aircraft were designed to perform identical missions using the same advanced technology and meeting the same operational constraints. The liquid hydrogen and Jet A fueled aircraft were compared on the basis of weight, size, energy utilization, cost, noise, emissions, safety, and operational characteristics. A program of technology development was formulated
Modification of silicon carbide fibers for use in SiC/Ti composites
The degradation of silicon carbide fibers during exposure to conditions typical of composite fabrication was investigated. The tensile strength of pristine fibers and fibers sputtered with thin metal coatings were determined before and after treatment at 870 C for one hour in vacuum. Each fiber strength distribution was related by an analytical procedure to a projected composite ultimate tensile strength (PC UTS). The results indicate that a thin aluminum diffusion barrier can yield a 150 percent increase in PC UTS over the baseline SiC/Ti system
WIMP astronomy and particle physics with liquid-noble and cryogenic direct-detection experiments
Once weakly-interacting massive particles (WIMPs) are unambiguously detected
in direct-detection experiments, the challenge will be to determine what one
may infer from the data. Here, I examine the prospects for reconstructing the
local speed distribution of WIMPs in addition to WIMP particle-physics
properties (mass, cross sections) from next-generation cryogenic and
liquid-noble direct-detection experiments. I find that the common method of
fixing the form of the velocity distribution when estimating constraints on
WIMP mass and cross sections means losing out on the information on the speed
distribution contained in the data and may lead to biases in the inferred
values of the particle-physics parameters. I show that using a more general,
empirical form of the speed distribution can lead to good constraints on the
speed distribution. Moreover, one can use Bayesian model-selection criteria to
determine if a theoretically-inspired functional form for the speed
distribution (such as a Maxwell-Boltzmann distribution) fits better than an
empirical model. The shape of the degeneracy between WIMP mass and cross
sections and their offset from the true values of those parameters depends on
the hypothesis for the speed distribution, which has significant implications
for consistency checks between direct-detection and collider data. In addition,
I find that the uncertainties on theoretical parameters depends sensitively on
the upper end of the energy range used for WIMP searches. Better constraints on
the WIMP particle-physics parameters and speed distribution are obtained if the
WIMP search is extended to higher energy (~ 1 MeV).Comment: 25 pages, 27 figures, matches published versio
Global Phase Diagram of the High Tc Cuprates
The high Tc cuprates have a complex phase diagram with many competing phases.
We propose a bosonic effective quantum Hamiltonian based on the projected SO(5)
model with extended interactions, which can be derived from the microscopic
models of the cuprates. The global phase diagram of this model is obtained
using mean-field theory and the Quantum Monte Carlo simulation, which is
possible because of the absence of the minus sign problem. We show that this
single quantum model can account for most salient features observed in the high
Tc cuprates, with different families of the cuprates attributed to different
traces in the global phase diagram. Experimental consequences are discussed and
new theoretical predictions are presented.Comment: 19 pages, 20 figures, with updated references, final versio
Monotonic Prefix Consistency in Distributed Systems
We study the issue of data consistency in distributed systems. Specifically,
we consider a distributed system that replicates its data at multiple sites,
which is prone to partitions, and which is assumed to be available (in the
sense that queries are always eventually answered). In such a setting, strong
consistency, where all replicas of the system apply synchronously every
operation, is not possible to implement. However, many weaker consistency
criteria that allow a greater number of behaviors than strong consistency, are
implementable in available distributed systems. We focus on determining the
strongest consistency criterion that can be implemented in a convergent and
available distributed system that tolerates partitions. We focus on objects
where the set of operations can be split into updates and queries. We show that
no criterion stronger than Monotonic Prefix Consistency (MPC) can be
implemented.Comment: Submitted pape
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