2,132 research outputs found

    Matter in inhomogeneous loop quantum cosmology: the Gowdy T(3) model

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    We apply a hybrid approach which combines loop and Fock quantizations to fully quantize the linearly polarized Gowdy T3T^3 model in the presence of a massless scalar field with the same symmetries as the metric. Like in the absence of matter content, the application of loop techniques leads to a quantum resolution of the classical cosmological singularity. Most importantly, thanks to the inclusion of matter, the homogeneous sector of the model contains flat Friedmann-Robertson-Walker (FRW) solutions, which are not allowed in vacuo. Therefore, this model provides a simple setting to study at the quantum level interesting physical phenomena such as the effect of the anisotropies and inhomogeneities on flat FRW cosmologies

    Measuring farmers' attitude towards breeding tools: the Livestock Breeding Attitude Scale

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    Under-use of genetic improvement tools and low participation in breeding programmes are key drivers of breeding programmes under-performance. Both aspects are heavily influenced by farmers attitudes which, to date, have not been analysed in an objective and systematic manner. A key factor constraining the implementation of attitudinal studies towards livestock breeding tools is the lack of a reference scale for measuring attitudes. In this research, we provide the livestock breeding sector with such a reference measure. We developed the scale following the standardized psychometric methodologies and statistical tools. Then, as a case study, we used the scale to explore the attitudes of beef and dairy sheep farmers in Australia, New Zealand and Spain and analysed farmer and farming system factors related to those attitudes. Fourteen sheep and beef breed associations facilitated the implementation of a survey of 547 farmers, generating data that was used for the scale evaluation. The relationship between attitudinal factors and farmer and farming system factors was analysed using generalized linear models across and within breeds. The results suggest that the 8-item definitive scale we have developed is appropriate to measure farmer attitudes. We found that attitudes towards genetic improvement tools have two components; i) traditional selection and ii) genetic and genomic selection combined. This means that positive attitudes towards traditional phenotypic selection do not necessarily imply a negative attitude towards genetic and genomic selection tools. Farmer attitudes varied greatly not only across the studied breeds, species and countries, but also within them. High-educated farmers of business-oriented farms tend to have the most negative attitude towards traditional selection. However, attitudes towards genetic and genomic selection tools could not be linked to these factors. Finally, we found that the breed raised had a large effect on farmer attitude. These findings may help in the evolution of breeding programmes by identifying both the farmers most inclined to uptake breeding innovations in the early stages of its establishment and the farmers who would be more reluctant to participate in such programmes, thus informing where to focus extension efforts

    Graph theory analysis of resting-state functional magnetic resonance imaging in essential tremor.

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    Essential tremor (ET) is a neurological disease with both motor and non-motor manifestations; however, little is known about its underlying brain basis. Furthermore, the overall organization of the brain network in ET remains largely unexplored. We investigated the topological properties of brain functional network, derived from resting-state functional MRI data, in 23 ET patients vs. 23 healthy controls. Graph theory analysis was used to assess the functional network organization. At the global level, the functional network of ET patients was characterized by lower small-world values than healthy controls - less clustered functionality of the brain. At the regional level, compared with the healthy controls, ET patients showed significantly higher values of global efficiency, cost and degree, and a shorter average path length in the left inferior frontal gyrus (pars opercularis), right inferior temporal gyrus (posterior division and temporo-occipital part), right inferior lateral occipital cortex, left paracingulate, bilateral precuneus bilaterally, left lingual gyrus, right hippocampus, left amygdala, nucleus accumbens bilaterally, and left middle temporal gyrus. In addition, ET patients showed significant higher local efficiency and clustering coefficient values in the frontal medial cortex bilaterally, subcallosal cortex, posterior cingulate, parahippocampal gyri bilaterally (posterior division), right lingual gyrus, right cerebellar flocculus, right postcentral gyrus, right inferior semilunar lobule of cerebellum and culmen of vermis. In conclusion, the efficiency of the overall brain functional network in ET is disrupted. Further, our results support the concept that ET is a disorder that disrupts widespread brain regions, including those outside of the brain regions responsible for tremor.pre-print1168 K

    Loop Quantum Gravity and the The Planck Regime of Cosmology

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    The very early universe provides the best arena we currently have to test quantum gravity theories. The success of the inflationary paradigm in accounting for the observed inhomogeneities in the cosmic microwave background already illustrates this point to a certain extent because the paradigm is based on quantum field theory on the curved cosmological space-times. However, this analysis excludes the Planck era because the background space-time satisfies Einstein's equations all the way back to the big bang singularity. Using techniques from loop quantum gravity, the paradigm has now been extended to a self-consistent theory from the Planck regime to the onset of inflation, covering some 11 orders of magnitude in curvature. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects, such as a modification of the consistency relation involving the scalar and tensor power spectra and a new source for non-Gaussianities. Thus, the genesis of the large scale structure of the universe can be traced back to quantum gravity fluctuations \emph{in the Planck regime}. This report provides a bird's eye view of these developments for the general relativity community.Comment: 23 pages, 4 figures. Plenary talk at the Conference: Relativity and Gravitation: 100 Years after Einstein in Prague. To appear in the Proceedings to be published by Edition Open Access. Summarizes results that appeared in journal articles [2-13

    Psychometric attributes of the DISC Predictive Scales

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    Introduction: This study was designed to evaluate the psychometric attributes and screening efficiency of a Spanish version of the Children Predictive Scales (DPS) against the Spanish Diagnostic Interview Schedule for Children (DISC-IV). Method: This pilot cross-sectional study included 61 children aged 9 to 14 years in a mainstream school. The following psychometric attributes were analyzed: acceptability, scale assumptions, internal consistency, and precision, as well the predictive validity (AUC). Results: The scale did not show ceiling or floor effects (6.4%, 1.3%, respectively). The internal consistency was high (α±=0.92), and the standard error of measurement was adequate (SEM=1.54). The overall DPS AUC was 0.72 against DISC IV corresponding diagnosis. Conclusion: The Spanish version of the DPS-4.32 seems to be a reliable and precise tool for screening mental health disorders in a school-age population

    Entropy in the Classical and Quantum Polymer Black Hole Models

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    We investigate the entropy counting for black hole horizons in loop quantum gravity (LQG). We argue that the space of 3d closed polyhedra is the classical counterpart of the space of SU(2) intertwiners at the quantum level. Then computing the entropy for the boundary horizon amounts to calculating the density of polyhedra or the number of intertwiners at fixed total area. Following the previous work arXiv:1011.5628, we dub these the classical and quantum polymer models for isolated horizons in LQG. We provide exact micro-canonical calculations for both models and we show that the classical counting of polyhedra accounts for most of the features of the intertwiner counting (leading order entropy and log-correction), thus providing us with a simpler model to further investigate correlations and dynamics. To illustrate this, we also produce an exact formula for the dimension of the intertwiner space as a density of "almost-closed polyhedra".Comment: 24 page

    Numerical loop quantum cosmology: an overview

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    A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and Quantum Gravity special issue on Non-Astrophysical Numerical Relativit

    Cost-Utility Analysis of a Medication Review with Follow-Up Service for Older Adults with Polypharmacy in Community Pharmacies in Spain: The conSIGUE Program

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    © 2015, Springer International Publishing Switzerland. Background: The concept of pharmaceutical care is operationalized through pharmaceutical professional services, which are patient-oriented to optimize their pharmacotherapy and to improve clinical outcomes. Objective: The objective of this study was to estimate the incremental cost-effectiveness ratio (ICER) of a medication review with follow-up (MRF) service for older adults with polypharmacy in Spanish community pharmacies against the alternative of having their medication dispensed normally. Methods: The study was designed as a cluster randomized controlled trial, and was carried out over a time horizon of 6 months. The target population was older adults with polypharmacy, defined as individuals taking five or more medicines per day. The study was conducted in 178 community pharmacies in Spain. Cost-utility analysis adopted a health service perspective. Costs were in euros at 2014 prices and the effectiveness of the intervention was estimated as quality-adjusted life-years (QALYs). In order to analyze the uncertainty of ICER results, we performed a non-parametric bootstrapping with 5000 replications. Results: A total of 1403 older adults, aged between 65 and 94 years, were enrolled in the study: 688 in the intervention group (IG) and 715 in the control group (CG). By the end of the follow-up, both groups had reduced the mean number of prescribed medications they took, although this reduction was greater in the IG (0.28 ± 1.25 drugs; p < 0.001) than in the CG (0.07 ± 0.95 drugs; p = 0.063). Older adults in the IG saw their quality of life improved by 0.0528 ± 0.20 (p < 0.001). In contrast, the CG experienced a slight reduction in their quality of life: 0.0022 ± 0.24 (p = 0.815). The mean total cost was €977.57 ± 1455.88 for the IG and €1173.44 ± 3671.65 for the CG. In order to estimate the ICER, we used the costs adjusted for baseline medications and QALYs adjusted for baseline utility score, resulting in a mean incremental total cost of −€250.51 ± 148.61 (95 % CI −541.79 to 40.76) and a mean incremental QALY of 0.0156 ± 0.004 (95 % CI 0.008–0.023). Regarding the results from the cost-utility analysis, the MRF service emerged as the dominant strategy. Conclusion: The MRF service is an effective intervention for optimizing prescribed medication and improving quality of life in older adults with polypharmacy in community pharmacies. The results from the cost-utility analysis suggest that the MRF service is cost effective
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