6,486 research outputs found
Development of an EOG (electro-oculography) based human-computer interface
Author name used in this publication: Kaiyu TongJockey Club Rehabilitation Engineering CentreRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe
Constraints on holographic dark energy models using the differential ages of passively evolving galaxies
Using the absolute ages of passively evolving galaxies observed at different
redshifts, one can obtain the differential ages, the derivative of redshift
with respect to the cosmic time (i.e. ). Thus, the
Hubble parameter can be measured through the relation . By comparing the measured Hubble parameter at different
redshifts with the theoretical one containing free cosmological parameters, one
can constrain current cosmological models. In this paper, we use this method to
present the constraint on a spatially flat Friedman-Robert-Walker Universe with
a matter component and a holographic dark energy component, in which the
parameter plays a significant role in this dark energy model. Firstly we
consider three fixed values of =0.6, 1.0 and 1.4 in the fitting of data. If
we set free, the best fitting values are , ,
. It is shown that the holographic dark energy behaves like a
quintom-type at the level. This result is consistent with some other
independent cosmological constrains, which imply that is favored. We
also test the results derived from the differential ages using another
independent method based on the lookback time to galaxy clusters and the age of
the universe. It shows that our results are reliable.Comment: 18 pages including 7 figures and 1 tables. Final version for
publication in Modern Physics Letters A (MPLA)[minor revision to match the
appear version
A model for luminescence of localized state ensemble
A distribution function for localized carriers,
, is proposed by solving a
rate equation, in which, electrical carriers' generation, thermal escape,
recapture and radiative recombination are taken into account. Based on this
distribution function, a model is developed for luminescence from localized
state ensemble with a Gaussian-type density of states. The model reproduces
quantitatively all the anomalous temperature behaviors of localized state
luminescence. It reduces to the well-known band-tail and luminescence quenching
models under certain approximations.Comment: 14 pages, 4 figure
Urban Crime Trends Analysis and Occurrence Possibility Prediction based on Light Gradient Boosting Machine
Big Data and Machine learning have been increasingly used to fight against Urban crimes. Our goal is to discover the connection between crime-related factors and the underlying complex crime pattern. Therefore, to predict the possibility of crime occurrence. Light Gradient Boosting Machine (LightGBM) Model is adopted in our study to predict the crime occurrence possibility based on actual crime information. We found that the prediction results are approximately consistent with an actual variation. We hope this work could help with crime prevention and policing
Angle-Resolved X-Ray Circular and Magnetic Circular Dichroisms: Definitions and Applications
We introduce definitions of angle-resolved x-ray circular dichroism (ARXCD) and magnetic x-ray circular dichroism (ARMXCD). As defined, the much larger effect of circular dichroism (ARXCD) is separated from the smaller magnetic (ARMXCD) effect. In all materials, ARXCD is zero along mirror planes while nonzero elsewhere. ARMXCD is nonzero only in magnetic materials. The measurement and analysis of ARMXCD allow element specific surface magnetism and surface structure as well as their inter-relationship to be studied as functions of the outgoing electron\u27s direction
Opportunities for improving waterlogging tolerance in cereal crops—Physiological traits and genetic mechanisms
Waterlogging occurs when soil is saturated with water, leading to anaerobic conditions in the root zone of plants. Climate change is increasing the frequency of waterlogging events, resulting in considerable crop losses. Plants respond to waterlogging stress by adventitious root growth, aerenchyma formation, energy metabolism, and phytohormone signalling. Genotypes differ in biomass reduction, photosynthesis rate, adventitious roots development, and aerenchyma formation in response to waterlogging. We reviewed the detrimental effects of waterlogging on physiological and genetic mechanisms in four major cereal crops (rice, maize, wheat, and barley). The review covers current knowledge on waterlogging tolerance mechanism, genes, and quantitative trait loci (QTL) associated with waterlogging tolerance-related traits, the conventional and modern breeding methods used in developing waterlogging tolerant germplasm. Lastly, we describe candidate genes controlling waterlogging tolerance identified in model plants Arabidopsis and rice to identify homologous genes in the less waterlogging-tolerant maize, wheat, and barley
Effect of a photoperiodic green light program during incubation on embryo development and hatch process
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