13,784 research outputs found
Implementation of complex interactions in a Cox regression framework
The standard Cox proportional hazards model has been extended by functionally describable interaction terms. The first of which are related to neural networks by adopting the idea of transforming sums of weighted covariables by means of a logistic function. A class of reasonable weight combinations within the logistic transformation is described. Apart from the standard covariable product interaction, a product of logistically transformed covariables has also been included in the analysis of performance of the new terms. An algorithm combining likelihood ratio tests and AIC criterion has been defined for model choice. The critical values of the likelihood ratio test statistics had to be corrected in order to guarantee a maximum type I error of 5% for each interaction term. The new class of interaction terms allows interpretation of functional relationships between covariables with more flexibility and can easily be implemented in standard software packages
Improving aquaculture feed in Bangladesh: From feed ingredients to farmer profit to safe consumption
Use of manufactured feeds in aquaculture in Bangladesh has grown rapidly over the last five years. More than 1 million tonnes of commercially formulated feeds and 0.3-0.4 million tonnes of farm-made feeds were produced in 2012, and sectoral growth is projected to increase substantially over the medium term. This working paper summarizes findings from a study, conducted as part of the WorldFish/USAID “Feed the Future-Aquaculture” project in 2012, assessing the current status of the aquaculture feed sector in Bangladesh. Fish feed value chains, market trends, ingredients and formulation systems, farm feeding practices, ancillary services and feed regulations were investigated. The study identifies a number of entry points for interventions in the sector, and investments which would improve feed quality and farmer access to better feeds and support the growth of sustainable aquaculture
Natural maps between CAT(0) boundaries
It is shown that certain natural maps between the ideal, Gromov, and end
boundaries of a complete CAT(0) space can fail to be either injective or
surjective. Additionally the natural map from the Gromov boundary to the end
boundary of a complete CAT(-1) space can fail to be either injective or
surjective.Comment: 8 page
Two-colour QCD with heavy quarks at finite densities
We extend the density-of-states approach to gauge systems (LLR method) to QCD
at finite temperature and density with heavy quarks. The approach features an
exponential error suppression and yields the Polyakov loop probability
distribution function over a range of more than hundred orders of magnitude.
SU(2) gauge theory is considered in the confinement and the high-temperature
phase, and at finite densities of heavy quarks. In the latter case, a smooth
rise of the density with the chemical potential is observed, and no critical
phenomenon associated with deconfinement due to finite densities is found.Comment: 4 pages, 5 figure
Rough CAT(0) spaces
We investigate various notions of rough CAT(0). These conditions define
classes of spaces that strictly include the union of all Gromov hyperbolic
length spaces and all CAT(0) spaces.Comment: Corrected typos and updated Corollaries 3.22 and 3.2
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