4,924 research outputs found
Exhaustive and Efficient Constraint Propagation: A Semi-Supervised Learning Perspective and Its Applications
This paper presents a novel pairwise constraint propagation approach by
decomposing the challenging constraint propagation problem into a set of
independent semi-supervised learning subproblems which can be solved in
quadratic time using label propagation based on k-nearest neighbor graphs.
Considering that this time cost is proportional to the number of all possible
pairwise constraints, our approach actually provides an efficient solution for
exhaustively propagating pairwise constraints throughout the entire dataset.
The resulting exhaustive set of propagated pairwise constraints are further
used to adjust the similarity matrix for constrained spectral clustering. Other
than the traditional constraint propagation on single-source data, our approach
is also extended to more challenging constraint propagation on multi-source
data where each pairwise constraint is defined over a pair of data points from
different sources. This multi-source constraint propagation has an important
application to cross-modal multimedia retrieval. Extensive results have shown
the superior performance of our approach.Comment: The short version of this paper appears as oral paper in ECCV 201
Many-Body Physics with Ultracold Gases
This article reviews recent experimental and theoretical progress on
many-body phenomena in dilute, ultracold gases. Its focus are effects beyond
standard weak-coupling descriptions, like the Mott-Hubbard-transition in
optical lattices, strongly interacting gases in one and two dimensions or
lowest Landau level physics in quasi two-dimensional gases in fast rotation.
Strong correlations in fermionic gases are discussed in optical lattices or
near Feshbach resonances in the BCS-BEC crossover.Comment: revised version, accepted for publication in Rev. Mod. Phy
Survey of the needs of patients with spinal cord injury: impact and priority for improvement in hand function in tetraplegics\ud
Objective: To investigate the impact of upper extremity deficit in subjects with tetraplegia.\ud
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Setting: The United Kingdom and The Netherlands.\ud
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Study design: Survey among the members of the Dutch and UK Spinal Cord Injury (SCI) Associations.\ud
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Main outcome parameter: Indication of expected improvement in quality of life (QOL) on a 5-point scale in relation to improvement in hand function and seven other SCI-related impairments.\ud
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Results: In all, 565 subjects with tetraplegia returned the questionnaire (overall response of 42%). Results in the Dutch and the UK group were comparable. A total of 77% of the tetraplegics expected an important or very important improvement in QOL if their hand function improved. This is comparable to their expectations with regard to improvement in bladder and bowel function. All other items were scored lower.\ud
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Conclusion: This is the first study in which the impact of upper extremity impairment has been assessed in a large sample of tetraplegic subjects and compared to other SCI-related impairments that have a major impact on the life of subjects with SCI. The present study indicates a high impact as well as a high priority for improvement in hand function in tetraplegics.\ud
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Mott Transition and Spin Structures of Spin-1 Bosons in Two-Dimensional Optical Lattice at Unit Filling
We study the ground state properties of spin-1 bosons in a two-dimensional
optical lattice, by applying a variational Monte Carlo method to the S=1
Bose-Hubbard model on a square lattice at unit filling. A doublon-holon binding
factor introduced in the trial state provides a noticeable improvement in the
variational energy over the conventional Gutzwiller wave function and allows us
to deal effectively with the inter-site correlations of particle densities and
spins. We systematically show how spin-dependent interactions modify the
superfluid-Mott insulator transitions in the S=1 Bose-Hubbard model due to the
interplay between the density and spin fluctuations of bosons. Furthermore,
regarding the magnetic phases in the Mott region, the calculated spin structure
factor elucidates the emergence of nematic and ferromagnetic spin orders for
antiferromagnetic () and ferromagnetic () couplings,
respectively.Comment: 5 pages, 5 figures, to appear in Journal of the Physical Society of
Japa
Role of Continuous Glucose Monitoring in Clinical Trials: Recommendations on Reporting.
Thanks to significant improvements in the precision, accuracy, and usability of continuous glucose monitoring (CGM), its relevance in both ambulatory diabetes care and clinical research is increasing. In this study, we address the latter perspective and derive provisional reporting recommendations. CGM systems have been available since around the year 2000 and used primarily in people with type 1 diabetes. In contrast to self-measured glucose, CGM can provide continuous real-time measurement of glucose levels, alerts for hypoglycemia and hyperglycemia, and a detailed assessment of glycemic variability. Through a broad spectrum of derived glucose data, CGM should be a useful tool for clinical evaluation of new glucose-lowering medications and strategies. It is the only technology that can measure hyperglycemic and hypoglycemic exposure in ambulatory care, or provide data for comprehensive assessment of glucose variability. Other advantages of current CGM systems include the opportunity for improved self-management of glycemic control, with particular relevance to those at higher risk of or from hypoglycemia. We therefore summarize the current status and limitations of CGM from the perspective of clinical trials and derive suggested recommendations for how these should facilitate optimal CGM use and reporting of data in clinical research
A multi-parent recombinant inbred line population of C. elegans allows identification of novel QTLs for complex life history traits
Background
The nematode Caenorhabditis elegans has been extensively used to explore the relationships between complex traits, genotypes, and environments. Complex traits can vary across different genotypes of a species, and the genetic regulators of trait variation can be mapped on the genome using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) derived from genetically and phenotypically divergent parents. Most RILs have been derived from crossing two parents from globally distant locations. However, the genetic diversity between local C. elegans populations can be as diverse as between global populations and could thus provide means of identifying genetic variation associated with complex traits relevant on a broader scale.
Results
To investigate the effect of local genetic variation on heritable traits, we developed a new RIL population derived from 4 parental wild isolates collected from 2 closely located sites in France: Orsay and Santeuil. We crossed these 4 genetically diverse parental isolates to generate a population of 200 multi-parental RILs and used RNA-seq to obtain sequence polymorphisms identifying almost 9000 SNPs variable between the 4 genotypes with an average spacing of 11 kb, doubling the mapping resolution relative to currently available RIL panels for many loci. The SNPs were used to construct a genetic map to facilitate QTL analysis. We measured life history traits such as lifespan, stress resistance, developmental speed, and population growth in different environments, and found substantial variation for most traits. We detected multiple QTLs for most traits, including novel QTLs not found in previous QTL analysis, including those for lifespan and pathogen responses. This shows that recombining genetic variation across C. elegans populations that are in geographical close proximity provides ample variation for QTL mapping.
Conclusion
Taken together, we show that using more parents than the classical two parental genotypes to construct a RIL population facilitates the detection of QTLs and that the use of wild isolates facilitates the detection of QTLs. The use of multi-parent RIL populations can further enhance our understanding of local adaptation and life history trade-offs
Phase diagram of two-component bosons on an optical lattice
We present a theoretical analysis of the phase diagram of two--component
bosons on an optical lattice. A new formalism is developed which treats the
effective spin interactions in the Mott and superfluid phases on the same
footing. Using the new approach we chart the phase boundaries of the broken
spin symmetry states up to the Mott to superfluid transition and beyond. Near
the transition point, the magnitude of spin exchange can be very large, which
facilitates the experimental realization of spin-ordered states. We find that
spin and quantum fluctuations have a dramatic effect on the transition making
it first order in extended regions of the phase diagram. For Mott states with
even occupation we find that the competition between effective Heisenberg
exchange and spin-dependent on--site interaction leads to an additional phase
transition from a Mott insulator with no broken symmetries into a spin-ordered
insulator
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