730 research outputs found

    Noncanonical Quantization of Gravity. I. Foundations of Affine Quantum Gravity

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    The nature of the classical canonical phase-space variables for gravity suggests that the associated quantum field operators should obey affine commutation relations rather than canonical commutation relations. Prior to the introduction of constraints, a primary kinematical representation is derived in the form of a reproducing kernel and its associated reproducing kernel Hilbert space. Constraints are introduced following the projection operator method which involves no gauge fixing, no complicated moduli space, nor any auxiliary fields. The result, which is only qualitatively sketched in the present paper, involves another reproducing kernel with which inner products are defined for the physical Hilbert space and which is obtained through a reduction of the original reproducing kernel. Several of the steps involved in this general analysis are illustrated by means of analogous steps applied to one-dimensional quantum mechanical models. These toy models help in motivating and understanding the analysis in the case of gravity.Comment: minor changes, LaTeX, 37 pages, no figure

    Virulence Factors and Pathogenicity of Mycobacterium

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    Virulence, is referred as the ability of a pathogen to cause disease, and for mycobacteria it depends on their ability to reside within host cells and evade the microbicidal mechanisms of macrophages. The outcome of tuberculosis (TB) infection is highly variable and it seems that the closest relationship between the Mycobacterium genre and humans has shaped the mycobacterial genome to encode bacterial factors that reflects a highly evolved and coordinated program of immune evasion strategies that interfere with both innate and adaptive immunity causing disease even in fully immunocompetent host. Although Mycobacterium tuberculosis (MTB) does not have classical virulence factors, it has described many virulence-associated genes and virulence lifestyle genes from Mycobacterium tuberculosis complex (MTBC). In this chapter, we describe the most important gene/molecule involved in the host defense modulation response, also the plethora of strategies to evade immune mechanisms of macrophage. We review the main genes whose inactivation in the mycobacterial genome leads to a measurable loss in virulence in the different validated TB models

    Effect of the biobased polyols chemical structure on high performance thermoset polyurethane properties

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    The sustainability of the polymeric materials has become a fundamental challenge; therefore, the development of new biobased formulations has gained increasing interest. Thermoset polyurethanes (PURs) present high performance and are a competitive solution for structural composites. However, polyols used in the PUR synthesis are typically from petrochemical origin. Nowdays, a broad range of biobased polyols is available in the market, but there is not yet a specific formulation for high performance PURs composites. The aim of this work was to study the effect of biobased polyols' characteristics in the PUR processing and final properties. In addition, biobased polyol features to synthesize BIO-PURs suitable for structural applications were stablished. The viscosity and reactivity were studied by means of rheology and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and flexural tests. The results obtained demonstrated the dramatic influence of polyols’ nature on BIO-PUR/PUR properties and their effect on the crosslink density. It was observed that using a high functionality and high hydroxyl index biobased polyol, it was possible to synthesize high performance BIO-PUR suitable for structural composites.We gratefully acknowledge the Basque Government for the financial support through the ELKARTEK 2021 (Project NEOMAT KK-2021/00059) program and in the frame of Grupos Consolidados (IT-1690-22). The authors also acknowledge the University of the Basque Country (UPV/EHU) in the frame of GIU18/216 Research Group and the Macrobehavior-Mesostructure-Nanotechnology SGIker unit

    Carve-Outs in Workers\u27 Compensation: An Analysis of the Experience in the California Construction Industry

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    Employers and unions in several states during the 1990s were allowed to carve out their own workers\u27 compensation systems. These innovative reforms gave the parties the right to collectively bargain their own systems outside the statutory systems. In addition, alternative dispute resolution (ADR) systems were implemented in order speed the legal process and reduce litigation costs. This book offers an evaluation of the first few years\u27 experience with these organizational reforms in California.https://research.upjohn.org/up_press/1054/thumbnail.jp

    Combining the Burrows-Wheeler Transform and RCM-LDGM Codes for the Transmission of Sources with Memory at High Spectral Efficiencies

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    In this paper, we look at the problem of implementing high-throughput Joint SourceChannel (JSC) coding schemes for the transmission of binary sources with memory over AWGN channels. The sources are modeled either by a Markov chain (MC) or a hidden Markov model (HMM). We propose a coding scheme based on the Burrows-Wheeler Transform (BWT) and the parallel concatenation of Rate-Compatible Modulation and Low-Density Generator Matrix (RCM-LDGM) codes. The proposed scheme uses the BWT to convert the original source with memory into a set of independent non-uniform Discrete Memoryless (DMS) binary sources, which are then separately encoded, with optimal rates, using RCM-LDGM codes

    The role of urban/rural environments on Mexican children’s connection to nature and pro-environmental behavior

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    Living in rural areas has been described a driver for behaving in a pro-environmental way, mainly due to the more frequent contact with nature that people from rural areas have. However, the processes that link living in a rural area and behaving in a more ecological manner have not been systematically studied. Moreover, most studies have focused on adults living in developed countries. Given the importance that the actions conducted by people in developing countries have for the future of the environment, as well as the relevance of children’s pro-environmentalism for nature conservation, we present a brief research report examining the relationship between Mexican children’s place of residence and self-reported pro-environmental behavior (PEB). Participants were 200 children from Mexican rural areas (150, 000 inhabitants). Children were between 9 and 12 years old. Children’s connection to nature was considered as a mediator in the relationship between children’s place of residence and PEB. Our findings revealed that rural children hold a stronger sense of connection to nature and behave in a more pro-environmental way than urban children. In addition, place of residence was directly and positively linked to their PEBs, and this relationship was mediated by children’s connection to nature. The relationship between connection to nature and PEB was stronger for girls than for boys. The model explained 45% of the variance of children’s self-reported PEBs

    Path Integrals, Density Matrices, and Information Flow with Closed Timelike Curves

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    Two formulations of quantum mechanics, inequivalent in the presence of closed timelike curves, are studied in the context of a soluable system. It illustrates how quantum field nonlinearities lead to a breakdown of unitarity, causality, and superposition using a path integral. Deutsch's density matrix approach is causal but typically destroys coherence. For each of these formulations I demonstrate that there are yet further alternatives in prescribing the handling of information flow (inequivalent to previous analyses) that have implications for any system in which unitarity or coherence are not preserved.Comment: 25 pages, phyzzx, CALT-68-188

    Proyecto eMadrid: metodologĂ­as educativas, ludificaciĂłn y calidad

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    Esta comunicación presenta un conjunto de trabajos de investigación sobre metodologías docentes, ludificación y calidad realizados en el seno del proyecto eMadrid, de la Comunidad Autónoma de Madrid. En primer lugar se resumen los trabajos realizados en los dos primeros años del proyecto. Posteriormente se presentan las líneas de trabajo previstas para los dos años restantesEstos trabajos se han financiado parcialmente por el proyecto eMadrid (S2013/ICE-2715) de la Comunidad de Madrid, los proyectos FLEXOR (TIN2014-52129-R), RESET (TIN2014-53199-C3-1-R) e iProg (TIN2015-66731-C2-1-R) del Ministerio de Economía y Competitividad, y el proyecto “Adaptación de la metodología PhyMEL a la formación clínica mediante el uso de simuladores” financiado por la empresa Medical Simulato

    Noise propagation issues in Belle II pixel detector power cable

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    The vertex detector used in the upgrade of High-Energy physics experiment Belle II includes DEPFET pixel detector (PXD) technology. In this complex topology the power supply units and the front-end electronics are connected through a PXD power cable bundle which may propagate the output noise from the power supplies to the vertex area. This paper presents a study of the propagation of noise caused by power converters in the PXD cable bundle based on Multi-conductor Transmission Line (MTL) theory. The work exposes the effect of the complex cable topology and shield connections on the noise propagation, which has an impact on the requirements of the power supplies. This analysis is part of the electromagnetic compatibility based design focused on functional safety to define the shield connections and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics

    Time travel paradoxes, path integrals, and the many worlds interpretation of quantum mechanics

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    We consider two approaches to evading paradoxes in quantum mechanics with closed timelike curves (CTCs). In a model similar to Politzer's, assuming pure states and using path integrals, we show that the problems of paradoxes and of unitarity violation are related; preserving unitarity avoids paradoxes by modifying the time evolution so that improbable events bewcome certain. Deutsch has argued, using the density matrix, that paradoxes do not occur in the "many worlds interpretation". We find that in this approach account must be taken of the resolution time of the device that detects objects emerging from a wormhole or other time machine. When this is done one finds that this approach is viable only if macroscopic objects traversing a wormhole interact with it so strongly that they are broken into microscopic fragments.Comment: no figure
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