8,471 research outputs found
Heavy Quark Physics From Lattice QCD
We review the application of lattice QCD to the phenomenology of b- and
c-quarks. After a short discussion of the lattice techniques used to evaluate
hadronic matrix elements and the corresponding systematic uncertainties, we
summarise results for leptonic decay constants, B--Bbar mixing, semileptonic
and rare radiative decays. A discussion of the determination of heavy quark
effective theory parameters is followed by an explanation of the difficulty in
applying lattice methods to exclusive nonleptonic decays.Comment: 52 pages LaTeX with 10 eps files. Requires: hfsprocl.sty (included)
plus axodraw.sty, rotating.sty and array.sty. To appear in Heavy Flavours
(2nd edition) edited by A J Buras and M Lindner (World Scientific,
Singapore). Revised version corrects typo in axis labelling of Fig 1
A dynamical and kinematical model of the Galactic stellar halo and possible implications for galaxy formation scenarios
We re-analyse the kinematics of the system of blue horizontal branch field
(BHBF) stars in the Galactic halo (in particular the outer halo), fitting the
kinematics with the model of radial and tangential velocity dispersions in the
halo as a function of galactocentric distance r proposed by Sommer-Larsen,
Flynn & Christensen (1994), using a much larger sample (almost 700) of BHBF
stars. The basic result is that the character of the stellar halo velocity
ellipsoid changes markedly from radial anisotropy at the sun to tangential
anisotropy in the outer parts of the Galactic halo (r greater than approx 20
kpc). Specifically, the radial component of the stellar halo's velocity
ellipsoid decreases fairly rapidly beyond the solar circle, from approx 140 +/-
10 km/s at the sun, to an asymptotic value of 89 +/- 19 km/s at large r. The
rapid decrease in the radial velocity dispersion is matched by an increase in
the tangential velocity dispersion, with increasing r.
Our results may indicate that the Galaxy formed hierarchically (partly or
fully) through merging of smaller subsystems - the 'bottom-up' galaxy formation
scenario, which for quite a while has been favoured by most theorists and
recently also has been given some observational credibility by HST observations
of a potential group of small galaxies, at high redshift, possibly in the
process of merging to a larger galaxy (Pascarelle et al 1996).Comment: Latex, 16 pages. 2 postscript figures. Submitted to the Astrophysical
Journal. also available at http://astro.utu.fi/~cflynn/outerhalo.htm
Assessing the Effectiveness of Automated Emotion Recognition in Adults and Children for Clinical Investigation
Recent success stories in automated object or face recognition, partly fuelled by deep learning artificial neural network (ANN) architectures, has led to the advancement of biometric research platforms and, to some extent, the resurrection of Artificial Intelligence (AI). In line with this general trend, inter-disciplinary approaches have taken place to automate the recognition of emotions in adults or children for the benefit of various applications such as identification of children emotions prior to a clinical investigation. Within this context, it turns out that automating emotion recognition is far from being straight forward with several challenges arising for both science(e.g., methodology underpinned by psychology) and technology (e.g., iMotions biometric research platform). In this paper, we present a methodology, experiment and interesting findings, which raise the following research questions for the recognition of emotions and attention in humans: a) adequacy of well-established techniques such as the International Affective Picture System (IAPS), b) adequacy of state-of-the-art biometric research platforms, c) the extent to which emotional responses may be different among children or adults. Our findings and first attempts to answer some of these research questions, are all based on a mixed sample of adults and children, who took part in the experiment resulting into a statistical analysis of numerous variables. These are related with, both automatically and interactively, captured responses of participants to a sample of IAPS pictures
decays and twisted boundary conditions
We propose a new method to evaluate the Lellouch-L\"uscher factor which
relates the matrix elements computed on a finite
lattice to the physical (infinite-volume) decay amplitudes. The method relies
on the use of partially twisted boundary conditions, which allow the s-wave
phase shift to be computed as an almost continuous function of the
centre-of-mass relative momentum and hence for its derivative to be evaluated.
We successfully demonstrate the feasibility of the technique in an exploratory
computation.Comment: 19 pages, 7 figure
Contaminated water treatment
Method and system for processing of a liquid ("contaminant liquid") containing water and containing urine and/or other contaminants in a two step process. Urine, or a contaminated liquid similar to and/or containing urine and thus having a relatively high salt and urea content is passed through an activated carbon filter to provide a resulting liquid, to remove most of the organic molecules. The resulting liquid is passed through a semipermeable membrane from a membrane first side to a membrane second side, where a fortified drink having a lower water concentration (higher osmotic potential) than the resulting liquid is positioned. Osmotic pressure differential causes the water, but not most of the remaining inorganic (salts) contaminant(s) to pass through the membrane to the fortified drink. Optionally, the resulting liquid is allowed to precipitate additional organic molecules before passage through the membrane
Bayesian inference for form-factor fits regulated by unitarity and analyticity
We propose a model-independent framework for fitting hadronic form-factor
data, which is often only available at discrete kinematical points, using
parameterisations based on to unitarity and analyticity. In this novel approach
the latter two properties of quantum-field theory regulate the ill-posed
fitting problem and allow model-independent predictions over the entire
physical range. Kinematical constraints, for example for the vector and scalar
form factors in semileptonic meson decays, can be imposed exactly. The core
formulae are straight-forward to implement with standard math libraries. We
take account of a generalisation of the original Boyd~Grinstein~Lebed (BGL)
unitarity constraint for form factors and demonstrate our method for the
exclusive semileptonic decay , for which we make a number of
phenomenologically relevant predictions, including the CKM matrix element
.Comment: 45 pages, 8 figures, references added, typos fixe
In situ aerosol measurements taken during the 2007 COPS field campaign at the Hornisgrinde ground site
Copyright @ 2011 Royal Meteorological Society.The Convective and Orographically-induced Precipitation Study (COPS) campaign was conducted during the summer of 2007. A suite of instruments housed at the top of the Hornisgrinde Mountain (1156 m) in the Black Forest region of south-west Germany provided datasets that allow an investigation into the physical, chemical and hygroscopic properties of the aerosol particles sampled during COPS. Organic mass loadings were found to dominate the aerosol composition for the majority of the project, exceeding 8 µg m−3 during a period of high pressure, high temperature, and low wind speed. The ratio of organic:sulphate sub-micron mass concentration exceeds 10:1 during the same time period. Back trajectories show air from this time-frame passing slowly over the local forest and not passing over any local anthropogenic sources. Occasional peaks in nitrate mass loadings were associated with changes in the typical wind direction from south-westerly to north-westerly where air had passed over the Stuttgart region. Size distribution data shows a dominant accumulation-mode when the measurement site was free from precipitation events. A sharp increase in ultrafine particle number concentration was seen during most days commencing around noon. The apparent growth of these particles is associated with an increase in organic mass loading, suggesting condensational growth. For the most part, with the exception of the high pressure period, the aerosol properties recorded during COPS were comparable to previous studies of continental aerosol properties.NER
External insulation systems for cryogenic storage systems - Bibliography/synopsis and category report /type 2 data/
Bibliography synopsis of external insulation materials and techniques for cryogenic storage system
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