480 research outputs found
Energy conservation in protected agriculture and the future of the UK glasshouse industry
Imperial Users onl
Quasilocal Center-of-Mass for Teleparallel Gravity
Asymptotically flat gravitating systems have 10 conserved quantities, which
lack proper local densities. It has been hoped that the teleparallel equivalent
of Einstein's GR (TEGR, aka GR) could solve this gravitational
energy-momentum localization problem. Meanwhile a new idea: quasilocal
quantities, has come into favor. The earlier quasilocal investigations focused
on energy-momentum. Recently we considered quasilocal angular momentum for the
teleparallel theory and found that the popular expression (unlike our
``covariant-symplectic'' one) gives the correct result only in a certain frame.
We now report that the center-of-mass moment, which has largely been neglected,
gives an even stronger requirement. We found (independent of the frame gauge)
that our ``covariant symplectic'' Hamiltonian-boundary-term quasilocal
expression succeeds for all the quasilocal quantities, while the usual
expression cannot give the desired center-of-mass moment. We also conclude,
contrary to hopes, that the teleparallel formulation appears to have no
advantage over GR with regard to localization.Comment: 12 pages, to appear in the proceedings of the 10th Marcel Grossman
meeting (Rio de Janeiro, 2003
Efficient Discovery of Ontology Functional Dependencies
Poor data quality has become a pervasive issue due to the increasing
complexity and size of modern datasets. Constraint based data cleaning
techniques rely on integrity constraints as a benchmark to identify and correct
errors. Data values that do not satisfy the given set of constraints are
flagged as dirty, and data updates are made to re-align the data and the
constraints. However, many errors often require user input to resolve due to
domain expertise defining specific terminology and relationships. For example,
in pharmaceuticals, 'Advil' \emph{is-a} brand name for 'ibuprofen' that can be
captured in a pharmaceutical ontology. While functional dependencies (FDs) have
traditionally been used in existing data cleaning solutions to model syntactic
equivalence, they are not able to model broader relationships (e.g., is-a)
defined by an ontology. In this paper, we take a first step towards extending
the set of data quality constraints used in data cleaning by defining and
discovering \emph{Ontology Functional Dependencies} (OFDs). We lay out
theoretical and practical foundations for OFDs, including a set of sound and
complete axioms, and a linear inference procedure. We then develop effective
algorithms for discovering OFDs, and a set of optimizations that efficiently
prune the search space. Our experimental evaluation using real data show the
scalability and accuracy of our algorithms.Comment: 12 page
Cross-Power Spectrum and Its Application on Window Functions in the WMAP data
Cross-power spectrum is a quadratic estimator between two maps that can
provide unbiased estimate of the underlying power spectrum of the correlated
signals, which is therefore used for extracting the power spectrum in the WMAP
data. In this paper we discuss the limit of cross-power spectrum and derive the
residual from uncorrelated signal, which is the source of error in power
spectrum extraction. We employ the estimator to extract window functions by
crossing pairs of extragalactic point sources. We desmonstrate its usefulness
in WMAP Difference Assembly maps where the window functions are measured via
Jupiter and then extract the window functions of the 5 WMAP frequency band
maps.Comment: added the part of applying cross power spectrum on WMAP DA maps and
frequency band maps and submitted to Ap
Direct measurement of the angular power spectrum of cosmic microwave background temperature anisotropies in the WMAP Data
Angular power spectrum of the cosmic microwave background (CMB) temperature
anisotropies is one of the most important on characteristics of the Universe
such as its geometry and total density. Using flat sky approximation and
Fourier analysis, we estimate the angular power spectrum from an ensemble of
least foreground-contaminated square patches from WMAP W and V frequency band
map. This method circumvents the issue of foreground cleaning and that of
breaking orthogonality in spherical harmonic analysis due to masking out the
bright Galactic plane region, thereby rendering a direct measurement of the
angular power spectrum. We test and confirm Gaussian statistical characteristic
of the selected patches, from which the first and second acoustic peak of the
power spectrum are reproduced, and the third peak is clearly visible albeit
with some noise residual at the tail.Comment: 13 pages, 5 figure
The Development of a Counseling Service Questionnaire: Study of Validation and Reliability
The study developed items of a counseling service questionnaire to aid counselors and universities in supporting students’ mental health. The participants of this study were 1,022 Chinese college students from three universities in Thailand. The questionnaire included development items and content validity and reliability testing. The questionnaire contained 17 items covering four aspects: (1) developmental counseling; (2) adaptive counseling; (3) disorder counseling; and (4) intervention in psychological crises. The results showed that the counseling services questionnaire is a valid and reliable instrument that can be used to determine students’ mental health
Anti-inflammatory and anti-infectious effects of Evodia rutaecarpa (Wuzhuyu) and its major bioactive components
This article reviews the anti-inflammatory relative and anti-infectious effects of Evodia rutaecarpa and its major bioactive components and the involvement of the nitric oxide synthases, cyclooxygenase, NADPH oxidase, nuclear factor kappa B, hypoxia-inducible factor 1 alpha, reactive oxygen species, prostaglandins, tumor necrosis factor, LIGHT, amyloid protein and orexigenic neuropeptides. Their potential applications for the treatment of endotoxaemia, obesity, diabetes, Alzheimer's disease and their uses as cardiovascular and gastrointestinal protective agents, analgesics, anti-oxidant, anti-atherosclerosis agents, dermatological agents and anti-infectious agents are highlighted. Stimulation of calcitonin gene-related peptide release may partially explain the analgesic, cardiovascular and gastrointestinal protective, anti-obese activities of Evodia rutaecarpa and its major bioactive components
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