Chaos in computer performance

Modern computer microprocessors are composed of hundreds of millions of transistors that interact through intricate protocols. Their performance during program execution may be highly variable and present aperiodic oscillations. In this paper, we apply current nonlinear time series analysis techniques to the performances of modern microprocessors during the execution of prototypical programs. Our results present pieces of evidence strongly supporting that the high variability of the performance dynamics during the execution of several programs display low-dimensional deterministic chaos, with sensitivity to initial conditions comparable to textbook models. Taken together, these results show that the instantaneous performances of modern microprocessors constitute a complex (or at least complicated) system and would benefit from analysis with modern tools of nonlinear and complexity science

Gauge transformations for higher-order lagrangians

Noether's symmetry transformations for higher-order lagrangians are studied. A characterization of these transformations is presented, which is useful to find gauge transformations for higher-order singular lagrangians. The case of second-order lagrangians is studied in detail. Some examples that illustrate our results are given; in particular, for the lagrangian of a relativistic particle with curvature, lagrangian gauge transformations are obtained, though there are no hamiltonian gauge generators for them.Comment: 22 pages, LaTe

Projective Fourier Duality and Weyl Quantization

The Weyl-Wigner correspondence prescription, which makes large use of Fourier duality, is reexamined from the point of view of Kac algebras, the most general background for noncommutative Fourier analysis allowing for that property. It is shown how the standard Kac structure has to be extended in order to accommodate the physical requirements. An Abelian and a symmetric projective Kac algebras are shown to provide, in close parallel to the standard case, a new dual framework and a well-defined notion of projective Fourier duality for the group of translations on the plane. The Weyl formula arises naturally as an irreducible component of the duality mapping between these projective algebras.Comment: LaTeX 2.09 with NFSS or AMSLaTeX 1.1. 102Kb, 44 pages, no figures. requires subeqnarray.sty, amssymb.sty, amsfonts.sty. Final version with text improvements and crucial typos correction

Accounting students' expectations and transition experiences of supervised work experience

Political and economic discourses position employability as a responsibility of higher education, which utilise mechanisms such as supervised work experience (SWE) to embed employability into the undergraduate curriculum. However, sparse investigation of students' contextualised experiences of SWE results in little being known about the mechanisms through which students derive employability benefits from SWE. The aim of this study is to examine the impact of students' expectation and conception of workplace learning on their transition into SWE. Analysis of accounting students' experiences reveal two broad conceptions of workplace learning, the differing impacts of which on transition experience are explored using existing learning transfer perspectives. Students displaying the more common 'technical' conception construct SWE as an opportunity to develop technical, knowledge-based expertise and abilities that prioritize product-based or cognitive learning transfer. Students with an 'experiential' conception were found to construct SWE primarily as an experience through which the development of personal skills and abilities beyond technical expertise are prioritized using process-based or socio-cultural learning transfer. Further data analysis suggests that these two learning transfer approaches have differing impacts on students' employability development which may indicate a need for universities to consider how to develop appropriate student expectations of and approaches to SWE and meaningful support for students' SWE transition

Recovery and valorisation of ancient varieties grown in high-altitude vineyards of the Spanish Pyrenees

O libro completo pódese descargar aquí: https://dialnet.unirioja.es/servlet/articulo?codigo=8455113[Abstract:] This project aims to recover ancient grapevine varieties in the Biescas area (Huesca, Spanish Pyrenees), after studying its molecular profile and agricultural and oenological potentials. The molecular analysis will be performed with eight microsatellites markers with high discriminant power and the profiles will be checked in national and international databases to determine the varietal identity. The oenological aptitude of these varieties will be evaluated with micro and standard vinifications carried out in Bal Minuta Cellar. To expand the commercial vineyard, a new plantation is planned in a currently abandoned field located near the recovered village of Barbenuta. Due to the mountainous climatic conditions, the high slope gradient of the field and the characteristics of the drainage area, the processes of water soil erosion and hydrological connectivity (HC) will be studied by means of field assessments and numerical modelling. The aggregated index of HC (AIC) will be run before and after plantation establishment. In this landscape, the abandoned and recovered fields are intermingled with patches of forestry areas where high walls and stone walls are frequent and influence on the runoff pathways. This initiative aims to recover abandoned fields, to identify ancient varieties and to valorise the potential of these varieties cultivated in vineyards located around 1200 m a.s.l. The achievement of these goals will allow a better transfer to the sector of the wines coming out of high altitude and will be of interest for the sustainability of the local economy. The project “Recovery and valorisation of old mountain vine varieties (Tierra de Biescas - Huesca)” has the support of (i) the Government of Aragon (Spain) through aid for cooperation actions of agents of the agricultural sector (Rural Development Program 2014-2020), and (ii) the European Agricultural Fund for Rural Development (EAFRD - FEADER). Preliminary results will be presented during the Congress

Analysis of prion protein gene (prnp) polymorphisms in healthy Morada Nova sheep reveals the presence of genotypes susceptible to scrapie.

Prion diseases, such as sheep scrapie, are usually associated with certain genotypes of prion protein gene (PRNP). Polymorphisms at codons 136, 154 and 171 of ovine PRNP open reading frame (ORF) are believed to confer either resistance or susceptibility to scrapie. In this study 72 healthy sheep from two different flocks, representing two meat type color variants from hair breed Morada Nova, from the State of Ceará, Brazil, were analyzed. PRNP ORF sequences were investigated for single nucleotide polymorphisms (SNPs) detection, followed by genotype analysis of codons 136, 154 and 171. Well known polymorphisms at codons 136 (coding for A/V) and 171 (coding for Q/R) were identified among the subjects, while at codon 154 only codon R has been observed. PRNP genotypes observed among Morada Nova subjects were ARQ/ ARQ (34.75%), ARQ/ARR (30.49%), ARR/ARR (31.92%) and the rare VRR/VRR (2.78%). We suggest here that the observed high homozygote frequency among Morada Nova PRNP genotypes AA at codon 136 and RR at codon 171 could be a genetic element for a putative natural resistance to scrapie. This is the first report of PRNP genotyping in Morada Nova breed and the first time the scrapie susceptible allele VRR has been identified in Brazil. RESUMO - Doenças priônicas, como o scrapie (Paraplexia Enzoótica dos Ovinos) estão usualmente associadas com determinados genótipos do gene da proteína priônica (PRNP). Polimorfismos na matriz aberta de leitura (ORF) dos códons 136, 154 e 171 de PRNP de ovinos estão associados a resistência ou suscetibilidade a scrapie. Neste estudo, um total de 72 ovinos saudáveis, de 2 rebanhos e diferente variação de cor de pelagem, da raça deslanada Morada Nova no Estado do Ceará, foram analisadas. Seqüências PRNP, compreendendo as ORF, do gene PRNP foram investigadas para a identificação dos Polimorfismos de único nucleotídeo (SNPs), seguida de detalhado seqüenciamento do DNA e análise bioinformática para os códons 136, 154 e 171. As freqüências genotípicas dos polimorfismos do PRNP são relatadas. Os polimorfismos já identificados no códon 136 (codificando A/V), 171 (codificando Q/R), entretanto no códon 154 não houve variação (somente R). As variantes alélicas e genotípicas para o PRNP observadas entre os ovinos Morada Nova foram: ARQ/ARQ (34,75%), ARQ/ARR (30,49%), ARR/ARR (31,92%) além do genótipo raro VRR/VRR (2,78%). Além das variantes alélicas e genótipicas, nós discutimos a freqüência da homozigozidade dos alelos AA no códon 136 e RR no códon 171 do PRNP e correspondentes haplótipos nos ovinos Morada Nova como elementos genéticos como um suposto elemento de resistência natural a scrapie. Este é o primeiro relato de genotipagem para PRNP em ovinos da raça Morada Nova e primeira observação do genótipo VRR/VRR em rebanho brasileiro

On the geometry of quantum indistinguishability

An algebraic approach to the study of quantum mechanics on configuration spaces with a finite fundamental group is presented. It uses, in an essential way, the Gelfand-Naimark and Serre-Swan equivalences and thus allows one to represent geometric properties of such systems in algebraic terms. As an application, the problem of quantum indistinguishability is reformulated in the light of the proposed approach. Previous attempts aiming at a proof of the spin-statistics theorem in non-relativistic quantum mechanics are explicitly recast in the global language inherent to the presented techniques. This leads to a critical discussion of single-valuedness of wave functions for systems of indistinguishable particles. Potential applications of the methods presented in this paper to problems related to quantization, geometric phases and phase transitions in spin systems are proposed.Comment: 24 page

Isometric Embeddings and Noncommutative Branes in Homogeneous Gravitational Waves

We characterize the worldvolume theories on symmetric D-branes in a six-dimensional Cahen-Wallach pp-wave supported by a constant Neveu-Schwarz three-form flux. We find a class of flat noncommutative euclidean D3-branes analogous to branes in a constant magnetic field, as well as curved noncommutative lorentzian D3-branes analogous to branes in an electric background. In the former case the noncommutative field theory on the branes is constructed from first principles, related to dynamics of fuzzy spheres in the worldvolumes, and used to analyse the flat space limits of the string theory. The worldvolume theories on all other symmetric branes in the background are local field theories. The physical origins of all these theories are described through the interplay between isometric embeddings of branes in the spacetime and the Penrose-Gueven limit of AdS3 x S3 with Neveu-Schwarz three-form flux. The noncommutative field theory of a non-symmetric spacetime-filling D-brane is also constructed, giving a spatially varying but time-independent noncommutativity analogous to that of the Dolan-Nappi model.Comment: 52 pages; v2: References adde

On the relation of optical obscuration and X-ray absorption in Seyfert galaxies

The optical classification of a Seyfert galaxy and whether it is considered X-ray absorbed are often used interchangeably. But there are many borderline cases and also numerous examples where the optical and X-ray classifications appear to be in conflict. In this article we re-visit the relation between optical obscuration and X-ray absorption in AGNs. We make use of our "dust color" method (Burtscher et al. 2015) to derive the optical obscuration A_V and consistently estimated X-ray absorbing columns using 0.3--150 keV spectral energy distributions. We also take into account the variable nature of the neutral gas column N_H and derive the Seyfert sub-classes of all our objects in a consistent way. We show in a sample of 25 local, hard-X-ray detected Seyfert galaxies (log L_X / (erg/s) ~ 41.5 - 43.5) that there can actually be a good agreement between optical and X-ray classification. If Seyfert types 1.8 and 1.9 are considered unobscured, the threshold between X-ray unabsorbed and absorbed should be chosen at a column N_H = 10^22.3 / cm^2 to be consistent with the optical classification. We find that N_H is related to A_V and that the N_H/A_V ratio is approximately Galactic or higher in all sources, as indicated previously. But in several objects we also see that deviations from the Galactic ratio are only due to a variable X-ray column, showing that (1) deviations from the Galactic N_H/A_V can simply be explained by dust-free neutral gas within the broad line region in some sources, that (2) the dust properties in AGNs can be similar to Galactic dust and that (3) the dust color method is a robust way to estimate the optical extinction towards the sublimation radius in all but the most obscured AGNs.Comment: 7 pages, 3 figures, accepted for publication by A&A; updated PDF to include abstrac

Semiclassical analysis of Wigner 3j3j-symbol

We analyze the asymptotics of the Wigner $3j$-symbol as a matrix element connecting eigenfunctions of a pair of integrable systems, obtained by lifting the problem of the addition of angular momenta into the space of Schwinger's oscillators. A novel element is the appearance of compact Lagrangian manifolds that are not tori, due to the fact that the observables defining the quantum states are noncommuting. These manifolds can be quantized by generalized Bohr-Sommerfeld rules and yield all the correct quantum numbers. The geometry of the classical angular momentum vectors emerges in a clear manner. Efficient methods for computing amplitude determinants in terms of Poisson brackets are developed and illustrated.Comment: 7 figure file