358 research outputs found
A study of order based genetic and evolutionary algorithms in combinatorial optimization problems
In Genetic and Evolutionary Algorithms (GEAs) one is faced with a given number of parameters, whose possible values are coded in a binary alphabet. With Order Based Representations (OBRs) the genetic information is kept by the order of the genes and not by its value. The application of OBRs to the Traveling Salesman Problem (TSP) is a well known technique to the GEA community. In this work one intends to show that this coding scheme can be used as an indirect representation, where the chromosome is the input for the decoder. The behavior of the GEA's operators is compared under benchmarks taken from the Combinatorial Optimization arena.(undefined
Comparing Pfizer GeneSTAR and Igenity PROFILE DNA tests in Crossbred Cattle
Our objective was to compare the performance of Pfizer’s GeneSTAR and Igenity’s PROFILE DNA tests in crossbred beef cattle. Hair follicles were collected from 394 crossbred steers that were part of the South Dakota State University Calf Value Discovery project (n = 145) and calves that were fed at the SDSU Southeast Research Farm (n = 249) in 2011. Hair follicles were sent to Pfizer Animal Genetics and Igenity for testing with their GeneSTAR and PROFILE DNA tests, respectively. Marbling score (100-999 scale), ribeye area, fat thickness, carcass weight, yield grade, quality grade, and % kidney, pelvic, and heart fat was collected post-harvest on all steers. Using this dataset, we first asked whether each DNA test was associated with marbling scores. If the DNA tests were not associated with marbling, then the tests may not be useful for predicting genetic merit for marbling in crossbred cattle. The GeneSTAR and PROFILE DNA tests were associated with marbling scores, but this association was not high. Second, we asked whether GeneSTAR and PROFILE DNA test results were associated with each other. If test results were not correlated, then using both DNA test results together may improve genetic predictions. GeneSTAR and PROFILE tests for tenderness were highly correlated, suggesting that DNA markers for tenderness are similar for both tests. GeneSTAR and PROFILE DNA tests for marbling and feed efficiency were not highly correlated, raising the possibility that both tests could be used jointly to improve genetic predictions for these traits. However, using both GeneSTAR and PROFILE DNA tests jointly did not appreciably improve predictions for marbling score in our dataset. We conclude that, although both GeneSTAR and PROFILE DNA tests were associated with marbling score, the correlation between these tests and marbling was low in our sample of crossbred cattle. Further, using GeneSTAR and PROFILE DNA tests for marbling and feed efficiency may improve genetic predictions for these traits, but we did not find evidence that using both tests jointly improves predictions for marbling
White matter impairment in the speech network of individuals with autism spectrum disorder
AbstractImpairments in language and communication are core features of Autism Spectrum Disorder (ASD), and a substantial percentage of children with ASD do not develop speech. ASD is often characterized as a disorder of brain connectivity, and a number of studies have identified white matter impairments in affected individuals. The current study investigated white matter integrity in the speech network of high-functioning adults with ASD. Diffusion tensor imaging (DTI) scans were collected from 18 participants with ASD and 18 neurotypical participants. Probabilistic tractography was used to estimate the connection strength between ventral premotor cortex (vPMC), a cortical region responsible for speech motor planning, and five other cortical regions in the network of areas involved in speech production. We found a weaker connection between the left vPMC and the supplementary motor area in the ASD group. This pathway has been hypothesized to underlie the initiation of speech motor programs. Our results indicate that a key pathway in the speech production network is impaired in ASD, and that this impairment can occur even in the presence of normal language abilities. Therapies that result in normalization of this pathway may hold particular promise for improving speech output in ASD
Calculation of nanowire thermal conductivity using complete phonon dispersion relations
The lattice thermal conductivity of crystalline Si nanowires is calculated.
The calculation uses complete phonon dispersions, and does not require any
externally imposed frequency cutoffs. No adjustment to nanowire thermal
conductivity measurements is required. Good agreement with experimental results
for nanowires wider than 35 nm is obtained. A formulation in terms of the
transmission function is given. Also, the use of a simpler, nondispersive
"Callaway formula", is discussed from the complete dispersions perspective.Comment: 4 pages, 3 figures. Accepted in Phys. Rev.
Input-output theory for fermions in an atom cavity
We generalize the quantum optical input-output theory developed for optical
cavities to ultracold fermionic atoms confined in a trapping potential, which
forms an "atom cavity". In order to account for the Pauli exclusion principle,
quantum Langevin equations for all cavity modes are derived. The dissipative
part of these multi-mode Langevin equations includes a coupling between cavity
modes. We also derive a set of boundary conditions for the Fermi field that
relate the output fields to the input fields and the field radiated by the
cavity. Starting from a constant uniform current of fermions incident on one
side of the cavity, we use the boundary conditions to calculate the occupation
numbers and current density for the fermions that are reflected and transmitted
by the cavity
A slip-based model for the size-dependent effective thermal conductivity of nanowires
The heat flux across a nanowire is computed based on the Guyer-Krumhansl
equation. Slip conditions with a slip length depending on both temperature and
nanowire radius are introduced at the outer boundary. An explicit expression
for the effective thermal conductivity is derived and compared to existing
models across a given temperature range, providing excellent agreement with
experimental data for Si nanowires
Two-fermion bound state in a Bose-Einstein condensate
A nonlinear Schr\"odinger equation is derived for the dynamics of a beam of
ultracold fermionic atoms traversing a Bose-Einstein condensate. The condensate
phonon modes are shown to provide a nonlinear medium for the fermionic atoms. A
two-fermion bound state is predicted to arise, and the signature of the bound
state in a nonlinear atom optics experiment is discussed.Comment: 4 pages, 1 figure
What do people do with porn? qualitative research into the consumption, use and experience of pornography and other sexually explicit media
This article reviews qualitative research into the consumption of pornography and other sexually explicit media emerging from a range of subject areas. Taking a critique of quantitative methods and a focus on measuring sexual effects and attitudes as a starting point, it considers the proposition that qualitative work is more suited to an examination of the complex social, cultural and political constructions of sexuality. Examining studies into the way men, women and young people see, experience, and use explicit media texts, the article identifies the key findings that have emerged. Qualitative work shows that sexuality explicit media texts are experienced and understood in a variety of ways and evoke strong and often contradictory reactions, not all of which are represented in public debates about pornography. These texts function in a range of different ways, depending on context; as a source of knowledge, a resource for intimate practices, a site for identity construction, and an occasion for performing gender and sexuality. The article reviews these studies and their findings, identifying what they suggest about directions for future research, both in terms of developing methodology and refining approaches to sexuality and media consumption.</p
Thermopower of a 2D electron gas in suspended AlGaAs/GaAs heterostructures
We present thermopower measurements on a high electron mobility
two-dimensional electron gas (2DEG) in a thin suspended membrane.We show that
the small dimension of the membrane substantially reduces the thermal
conductivity compared to bulk material so that it is possible to establish a
strong thermal gradient along the 2DEG even at a distance of few micrometers.
We find that the zero-field thermopower is significantly affected by the micro
patterning. In contrast to 2DEGs incorporated in a bulk material, the diffusion
contribution to the thermopower stays dominant up to a temperature of 7 K until
the phonon-drag becomes strong and governs the run of the thermopower. We also
find that the coupling between electrons and phonons in the phonon-drag regime
is due to screened deformation potentials, in contrast to piezoelectric
coupling found with bulk phonons.Comment: 7 page
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