6,152 research outputs found
Prediction with Dimension Reduction of Multiple Molecular Data Sources for Patient Survival
Predictive modeling from high-dimensional genomic data is often preceded by a
dimension reduction step, such as principal components analysis (PCA). However,
the application of PCA is not straightforward for multi-source data, wherein
multiple sources of 'omics data measure different but related biological
components. In this article we utilize recent advances in the dimension
reduction of multi-source data for predictive modeling. In particular, we apply
exploratory results from Joint and Individual Variation Explained (JIVE), an
extension of PCA for multi-source data, for prediction of differing response
types. We conduct illustrative simulations to illustrate the practical
advantages and interpretability of our approach. As an application example we
consider predicting survival for Glioblastoma Multiforme (GBM) patients from
three data sources measuring mRNA expression, miRNA expression, and DNA
methylation. We also introduce a method to estimate JIVE scores for new samples
that were not used in the initial dimension reduction, and study its
theoretical properties; this method is implemented in the R package R.JIVE on
CRAN, in the function 'jive.predict'.Comment: 11 pages, 9 figure
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Commodities and Linkages: Meeting the Policy Challenge
The results of detailed empirical enquiry into the nature and determinants of the breadth and depth of linkages in and out of the commodities sector in eight SSA countries (Angola, Botswana, Gabon, Ghana, Nigeria, South Africa Tanzania, and Zambia) and six sectors (copper, diamonds, gold, oil and gas, mining services and timber) has shown extensive scope for industrial development (MMCP DP 13, 2011). A primary conclusion of this research was that policy in both the private and public realm was a prime factor holding back the development of linkages. Addressing this problem requires the closing of three sets of misalignments between policy and practice – within the corporate sector, within the public sector, and between the public sector and other stakeholders involved in linkage development. In addition, specific policies need to be developed, monitored and implemented in relation to the three contextual drivers of linkages from the commodity sector – skills and capabilities, infrastructure and policies towards ownership
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Commodities and Linkages: Industrialisation in Sub-Saharan Africa
In a complementary Discussion Paper (MMCP DP 12 2011) we set out the reasons why we believe that there is extensive scope for linkage development into and out of SSA’s commodities sectors. In this Discussion Paper, we present the findings of our detailed empirical enquiry into the determinants of the breadth and depth of linkages in eight SSA countries (Angola, Botswana, Gabon, Ghana, Nigeria, South Africa Tanzania, and Zambia) and six sectors (copper, diamonds, gold, oil and gas, mining services and timber). We conclude from this detailed research that the extent of linkages varies as a consequence of four factors which intrinsically affect their progress – the passage of time, the complexity of the sector and the level of capabilities in the domestic economy. However, beyond this we identify three sets of related factors which determined the nature and pace of linkage development. The first is the structure of ownership, both in lead commodity producing firms and in their suppliers and domestic customers. The second is the nature and quality of both hard infrastructure (for example, roads and ports) and soft infrastructure (for example, the efficiency of customs clearance). The third is the availability of skills and the structure and orientation of the National System of Innovation in the domestic economy. The fourth, and overwhelmingly important contextual factor is policy. This reflects policy towards the commodity sector itself, and policy which affects the three contextual drivers, namely ownership, infrastructure and capabilities. As a result of this comparative analysis we provided an explanation of why linkage development was progressive in some economies (such as Botswana) and regressive in others (such as Tanzania). This cluster of factors also explains why the breadth and depth of linkages is relative advanced in some countries (such as South Africa), and at a very nascent stage in other countries (such as Angola)
Greening in the United States hotel sector: An exploratory examination
The aim of this paper is to explore the concept of greening in the U.S. hotel sector. Much of the existing research on the topic of greening is relegated to the European and Asian hotel sectors. Within the literature review, the paper will examine what industry leaders and scholars have reported about the progress of greening in the global sector. Given the scant research domestically, the paper will attempt to generalize some of the findings to the situation in the U.S. hotel sector. The paper’s methodology section will build on European research on greening and develop a blueprint for U.S. hotels to measure their environmental impact and reveal ways they may have addressed it within their operations. A proposed questionnaire, if distributed to property-level general managers, may provide an indication of the extent greening has caught on in the U.S. hotel sector. This paper will contribute to the existing body of research and provide insight as to why some hoteliers have adopted green programs, while others have failed to do so
Path planning and energy management of solar-powered unmanned ground vehicles
Many of the applications pertinent to unmanned vehicles, such as environmental research and analysis, communications, and information-surveillance and reconnaissance, benefit from prolonged vehicle operation time. Conventional efforts to increase the operational time of electric-powered unmanned vehicles have traditionally focused on the design of energy-efficient components and the identification of energy efficient search patterns, while little attention has been paid to the vehicle\u27s mission-level path plan and power management. This thesis explores the formulation and generation of integrated motion-plans and power-schedules for solar-panel equipped mobile robots operating under strict energy constraints, which cannot be effectively addressed through conventional motion planning algorithms. Transit problems are considered to design time-optimal paths using both Balkcom-Mason and Pseudo-Dubins curves. Additionally, a more complicated problem to generate mission plans for vehicles which must persistently travel between certain locations, similar to the traveling salesperson problem (TSP), is presented. A comparison between one of the common motion-planning algorithms and experimental results of the prescribed algorithms, made possible by use of a test environment and mobile robot designed and developed specifically for this research, are presented and discussed
EXPERIMENTS AND ANALYSIS OF ALUMINUM TUBE HYDROFORMING
This is a thesis on the development of an experimental table-top sized tube hydroforming machine at the University of New Hampshire. This thesis documents the design of the machine and the exploration of the forming envelope of the device via finite element modeling of the forming process. Several experiments on Al-6061-T4 tubes were used to evaluate the plastic behavior and strain limits of the tube in the axial and circumferential (hoop) directions. Two of these material tests, the uniaxial tension test and the ring hoop tension tests, were simulated with finite element models to refine the Al-6061-T4 plasticity curve, including the extrapolation of the hardening curve beyond the point of ultimate tensile stress. 2D and 3D finite element models of the hydroforming process were also used to evaluate potential tube materials, outer diameters, and wall-thickness for future experiments and research efforts
A New Mechanism for Light Composite Higgs Bosons
Repeated symmetry-breaking and restoration phase transitions occur as one
traverses the parameter space of interactions competing to align the vacuum.
This phenomenon, augmented with a topcolor-like interaction, can make a
composite Higgs boson's mass and vacuum expectation value naturally much less
than its underlying structure scale, without introducing new symmetries and
their associated TeV-scale particles. We illustrate it by reconstructing a
simple light composite Higgs model of electroweak symmetry breaking proposed by
Georgi and Kaplan.Comment: 9 pages, 4 postscript figures, LaTe
Reconciling optical and radio observations of the binary millisecond pulsar PSR J1640+2224
Previous optical and radio observations of the binary millisecond pulsar PSR
J1640+2224 have come to inconsistent conclusions about the identity of its
companion, with some observations suggesting the companion is a low-mass
helium-core (He-core) white dwarf (WD), while others indicate it is most likely
a high-mass carbon-oxygen (CO) WD. Binary evolution models predict PSR
J1640+2224 most likely formed in a low-mass X-ray binary (LMXB) based on the
pulsar's short spin period and long-period, low-eccentricity orbit, in which
case its companion should be a He-core WD with mass about , depending on metallicity. If it is instead a CO WD, that would
suggest the system has an unusual formation history. In this paper we present
the first astrometric parallax measurement for this system from observations
made with the Very Long Baseline Array (VLBA), from which we determine the
distance to be . We use this distance and a
reanalysis of archival optical observations originally taken in 1995 with the
Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST) in
order to measure the WD's mass. We also incorporate improvements in
calibration, extinction model, and WD cooling models. We find that the existing
observations are not sufficient to tightly constrain the companion mass, but we
conclude the WD mass is with confidence. The limiting
factor in our analysis is the low signal-to-noise ratio of the original HST
observations.Comment: 6 pages, 5 figure
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