70,596 research outputs found
Brave New World: Can We Engineer a Better Start for Freshers?
Abstract - The crucial importance of first experiences in shaping future success has been widely acknowledged. Creating the best foundations in large cohorts of students from diverse backgrounds presents special problems of its own. But a secure foundation can enhance student achievement and improve retention – and the students may even have fun too. Research has suggested that building learning communities can enhance student engagement and achievement. This paper examines how introducing non-technical activities can establish sound foundations for a university career by a) addressing objectives in the wider curriculum and b) promoting non-technical skills and experience of group working. A set of changes introduced to five degree cohorts in our academic school were designed to complement enhancements to our technical curriculum introduced during many years of debate and consideration. The changes have impacted upon generic and technical educational experiences. The paper presents an evaluation of the programme of changes through two iterations from the perspective of both faculty and student
Cosmology of the Next-to-Minimal Supersymmetric Standard Model
We discuss the domain wall problem in the Next-to-Minimal Supersymmetric
Standard Model, with particular attention to the usual solution of explicit
breaking of the discrete symmetry by non-renormalisable operators. This
``solution'' leads to a contradiction between the requirements of cosmology and
those of avoiding the destabilisation of the hierarchy.Comment: 6 pages LaTeX, needs sprocl.sty (included at end) Talk presented by
P.L. White at Valencia 9
A Two-dimensional Infinte System Density Matrix Renormalization Group Algorithm
It has proved difficult to extend the density matrix renormalization group
technique to large two-dimensional systems. In this Communication I present a
novel approach where the calculation is done directly in two dimensions. This
makes it possible to use an infinite system method, and for the first time the
fixed point in two dimensions is studied. By analyzing several related blocking
schemes I find that there exists an algorithm for which the local energy
decreases monotonically as the system size increases, thereby showing the
potential feasibility of this method.Comment: 5 pages, 6 figure
The critical behaviour of the 2D Ising model in Transverse Field; a Density Matrix Renormalization calculation
We have adjusted the Density Matrix Renormalization method to handle two
dimensional systems of limited width. The key ingredient for this extension is
the incorporation of symmetries in the method. The advantage of our approach is
that we can force certain symmetry properties to the resulting ground state
wave function. Combining the results obtained for system sizes up-to and finite size scaling, we derive the phase transition point and the
critical exponent for the gap in the Ising model in a Transverse Field on a two
dimensional square lattice.Comment: 9 pages, 8 figure
MCMC methods for functions modifying old algorithms to make\ud them faster
Many problems arising in applications result in the need\ud
to probe a probability distribution for functions. Examples include Bayesian nonparametric statistics and conditioned diffusion processes. Standard MCMC algorithms typically become arbitrarily slow under the mesh refinement dictated by nonparametric description of the unknown function. We describe an approach to modifying a whole range of MCMC methods which ensures that their speed of convergence is robust under mesh refinement. In the applications of interest the data is often sparse and the prior specification is an essential part of the overall modeling strategy. The algorithmic approach that we describe is applicable whenever the desired probability measure has density with respect to a Gaussian process or Gaussian random field prior, and to some useful non-Gaussian priors constructed through random truncation. Applications are shown in density estimation, data assimilation in fluid mechanics, subsurface geophysics and image registration. The key design principle is to formulate the MCMC method for functions. This leads to algorithms which can be implemented via minor modification of existing algorithms, yet which show enormous speed-up on a wide range of applied problems
Use of record-linkage to handle non-response and improve alcohol consumption estimates in health survey data: a study protocol
<p>Introduction: Reliable estimates of health-related behaviours, such as levels of alcohol consumption in the population, are required to formulate and evaluate policies. National surveys provide such data; validity depends on generalisability, but this is threatened by declining response levels. Attempts to address bias arising from non-response are typically limited to survey weights based on sociodemographic characteristics, which do not capture differential health and related behaviours within categories. This project aims to explore and address non-response bias in health surveys with a focus on alcohol consumption.</p>
<p>Methods and analysis: The Scottish Health Surveys (SHeS) aim to provide estimates representative of the Scottish population living in private households. Survey data of consenting participants (92% of the achieved sample) have been record-linked to routine hospital admission (Scottish Morbidity Records (SMR)) and mortality (from National Records of Scotland (NRS)) data for surveys conducted in 1995, 1998, 2003, 2008, 2009 and 2010 (total adult sample size around 40 000), with maximum follow-up of 16 years. Also available are census information and SMR/NRS data for the general population. Comparisons of alcohol-related mortality and hospital admission rates in the linked SHeS-SMR/NRS with those in the general population will be made. Survey data will be augmented by quantification of differences to refine alcohol consumption estimates through the application of multiple imputation or inverse probability weighting. The resulting corrected estimates of population alcohol consumption will enable superior policy evaluation. An advanced weighting procedure will be developed for wider use.</p>
<p>Ethics and dissemination: Ethics approval for SHeS has been given by the National Health Service (NHS) Multi-Centre Research Ethics Committee and use of linked data has been approved by the Privacy Advisory Committee to the Board of NHS National Services Scotland and Registrar General. Funding has been granted by the MRC. The outputs will include four or five public health and statistical methodological international journal and conference papers.</p>
The Radio Spectrum of TVLM513-46546: Constraints on the Coronal Properties of a Late M Dwarf
We explore the radio emission from the M9 dwarf, TVLM513-46546, at multiple
radio frequencies, determining the flux spectrum of persistent radio emission,
as well as constraining the levels of circular polarization. Detections at both
3.6 and 6 cm provide spectral index measurement (where S) of . A detection at 20 cm suggests that the
spectral peak is between 1.4 and 5 GHz. The most stringent upper limits on
circular polarization are at 3.6 and 6 cm, with 15%. These
characteristics agree well with those of typical parameters for early to mid M
dwarfs, confirming that magnetic activity is present at levels comparable with
those extrapolated from earlier M dwarfs. We apply analytic models to
investigate the coronal properties under simple assumptions of dipole magnetic
field geometry and radially varying nonthermal electron density distributions.
Requiring the spectrum to be optically thin at frequencies higher than 5 GHz
and reproducing the observed 3.6 cm fluxes constrains the magnetic field at the
base to be less than about 500 G. There is no statistically significant
periodicity in the 3.6 cm light curve, but it is consistent with low-level
variability.Comment: 11 pages, 2 figures Accepted for publication in the Astrophysical
Journa
Effects of nanoscale spatial inhomogeneity in strongly correlated systems
We calculate ground-state energies and density distributions of Hubbard
superlattices characterized by periodic modulations of the on-site interaction
and the on-site potential. Both density-matrix renormalization group and
density-functional methods are employed and compared. We find that small
variations in the on-site potential can simulate, cancel, or even
overcompensate effects due to much larger variations in the on-site interaction
. Our findings highlight the importance of nanoscale spatial inhomogeneity
in strongly correlated systems, and call for reexamination of model
calculations assuming spatial homogeneity.Comment: 5 pages, 1 table, 4 figures, to appear in PR
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