2,080 research outputs found
Intersection tests for single marker QTL analysis can be more powerful than two marker QTL analysis
BACKGROUND: It has been reported in the quantitative trait locus (QTL) literature that when testing for QTL location and effect, the statistical power supporting methodologies based on two markers and their estimated genetic map is higher than for the genetic map independent methodologies known as single marker analyses. Close examination of these reports reveals that the two marker approaches are more powerful than single marker analyses only in certain cases. Simulation studies are a commonly used tool to determine the behavior of test statistics under known conditions. We conducted a simulation study to assess the general behavior of an intersection test and a two marker test under a variety of conditions. The study was designed to reveal whether two marker tests are always more powerful than intersection tests, or whether there are cases when an intersection test may outperform the two marker approach. We present a reanalysis of a data set from a QTL study of ovariole number in Drosophila melanogaster. RESULTS: Our simulation study results show that there are situations where the single marker intersection test equals or outperforms the two marker test. The intersection test and the two marker test identify overlapping regions in the reanalysis of the Drosophila melanogaster data. The region identified is consistent with a regression based interval mapping analysis. CONCLUSION: We find that the intersection test is appropriate for analysis of QTL data. This approach has the advantage of simplicity and for certain situations supplies equivalent or more powerful results than a comparable two marker test
An extension of SPARQL for expressing qualitative preferences
In this paper we present SPREFQL, an extension of the SPARQL language that
allows appending a PREFER clause that expresses "soft" preferences over the
query results obtained by the main body of the query. The extension does not
add expressivity and any SPREFQL query can be transformed to an equivalent
standard SPARQL query. However, clearly separating preferences from the "hard"
patterns and filters in the WHERE clause gives queries where the intention of
the client is more cleanly expressed, an advantage for both human readability
and machine optimization. In the paper we formally define the syntax and the
semantics of the extension and we also provide empirical evidence that
optimizations specific to SPREFQL improve run-time efficiency by comparison to
the usually applied optimizations on the equivalent standard SPARQL query.Comment: Accepted to the 2017 International Semantic Web Conference, Vienna,
October 201
On the Mixing of the Scalar Mesons , and
Based on a mass matrix describing the mixing of the scalar states
, and , the hadronic decays of the three
states are investigated. Taking into account the two possible assumptions
concerning the mass level order of the bare states
, and in the
scalar sector, and , we obtain the
glueball-quarkonia content of the three states by solving the unlinear
equations. Some predictions about the decays of the three states in two cases
are presented, which can provide a stringent consistency check of the two
assumptions.Comment: revtex 10 pages, 1 eps figur
The Role of Bike Sharing in Promoting Transport Resilience
A resilient transport network, which is significant for urban sustainability and security,
is characterized by its ability to recover from disruptions subject to natural and manmade disasters. Bike sharing could act as a viable alternative in the case of public transit
disruptions given its flexibility and various social, environmental, and economic
benefits. This study aims to estimate quantitatively the potential of bike sharing to
promote transport resilience, by using autoregressive negative binomial time series
model to investigate the effects of public transit closures on bike sharing demand in
Washington, D.C. area during 2015â2017. We find that (1) bike sharing can act as a
supplementary mode to enhance urban transport resilience in the case of complete
transit closure; (2) the proximity of bike sharing docks to metro stations has a powerful
effect on propensity to use a bike sharing program; and (3) extreme weather is one of
major barriers to bicycling. Planners can enhance resilience of urban transport networks
by fully considering the capacity and usage of bike sharing docks, as well as the
coherence of metro stations and bike sharing docks, in distributing and rebalancing
activitie
Aerodynamic characteristics of a large scale lift fan transport model with podded fans forward and lift cruise fans mounted above the wing
The aerodynamic characteristics of a large scale V/STOL transport model powered by tip-turbine driven lift fans were investigated. The model had four fans; the forward fans were mounted in pods forward of the wing at midsemispan. The aft fans were placed in cruise nacelles behind and above the wing. A cascade of variable camber exit louvers was placed behind each of the lift-cruise fans to turn the fan flow in the lift direction for hover and transition to wing supported flight. The wing of the model was mounted above the fuselage, had an aspect ratio of 5.8, sweepback of 35 deg at the quarter chord line and a taper ratio of 0.3. Various configurations of the model were tested to explore the transition speed range. Fan performance, turning effectiveness of the variable camber exit louvers, longitudinal and lateral-directional characteristics with fan operation in crossflow are presented
Asymptotic Expansions for the Conditional Sojourn Time Distribution in the -PS Queue
We consider the queue with processor sharing. We study the
conditional sojourn time distribution, conditioned on the customer's service
requirement, in various asymptotic limits. These include large time and/or
large service request, and heavy traffic, where the arrival rate is only
slightly less than the service rate. The asymptotic formulas relate to, and
extend, some results of Morrison \cite{MO} and Flatto \cite{FL}.Comment: 30 pages, 3 figures and 1 tabl
Identification of co-regulated transcripts affecting male body size in Drosophila
Factor analysis is an analytic approach that describes the covariation among a set of genes through the estimation of 'factors', which may be, for example, transcription factors, microRNAs (miRNAs), and so on, by which the genes are co-regulated. Factor analysis gives a direct mechanism by which to relate gene networks to complex traits. Using simulated data, we found that factor analysis clearly identifies the number and structure of factors and outperforms hierarchical cluster analysis. Noise genes, genes that are not correlated with any factor, can be distinguished even when factor structure is complex. Applied to body size in Drosophila simulans, an evolutionarily important complex trait, a factor was directly associated with body size
Impacts of Geographic Distance on Peritoneal Dialysis Utilization: Refining Models of Treatment Selection
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/136011/1/hesr12489.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136011/2/hesr12489-sup-0001-AuthorMatrix.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136011/3/hesr12489_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136011/4/hesr12489-sup-0002-Appendix.pd
- âŠ