Unitarity of Quantum Theory and Closed Time-Like Curves

Interacting quantum fields on spacetimes containing regions of closed timelike curves (CTCs) are subject to a non-unitary evolution $X$. Recently, a prescription has been proposed, which restores unitarity of the evolution by modifying the inner product on the final Hilbert space. We give a rigorous description of this proposal and note an operational problem which arises when one considers the composition of two or more non-unitary evolutions. We propose an alternative method by which unitarity of the evolution may be regained, by extending $X$ to a unitary evolution on a larger (possibly indefinite) inner product space. The proposal removes the ambiguity noted by Jacobson in assigning expectation values to observables localised in regions spacelike separated from the CTC region. We comment on the physical significance of the possible indefiniteness of the inner product introduced in our proposal.Comment: 13 pages, LaTeX. Final revised paper to be published in Phys Rev D. Some changes are made to expand our discussion of Anderson's Proposal for restoring unitarit

Mentalizing in an economic games context is associated with enhanced activation and connectivity in the left temporoparietal junction.

Prior studies in Social Neuroeconomics have consistently reported activation in social cognition regions during interactive economic games, suggesting mentalizing during economic choice. Such mentalizing occurs during active participation in the game, as well as during passive observation of others' interactions. We designed a novel version of the classic false-belief task (FBT) in which participants read vignettes about interactions between agents in the ultimatum and trust games and were subsequently asked to infer the agents' beliefs. We compared activation patterns during the economic games FBT to those during the classic FBT using conjunction analyses. We find significant overlap in the left temporoparietal junction (TPJ) and dorsal medial prefrontal cortex, as well as the temporal pole (TP) during two task phases: belief formation and belief inference. Moreover, generalized Psychophysiological Interaction (gPPI) analyses show that during belief formation, the right TPJ is a target of both the left TPJ and the right TP seed regions, whereas during belief inferences all seed regions show interconnectivity with each other. These results indicate that across different task types and phases, mentalizing is associated with activation and connectivity across central nodes of the social cognition network. Importantly, this is the case for both the novel economic games and the classic FBTs

Individual responder analysis of effectiveness of manual therapy and exercise versus usual care in neck pain patients: preliminary results of a randomized controlled trial

Trabalho apresentado no 10th Congress of European Pain Federation (EFIC), 6-9 setembro 2017, Copenhaga, DinamarcaN/

Processing and characterization of glass-ceramic foams belonging to the Li2O-ZrO2-Al2O3-SiO2 (LZSA) system produced by gelcasting

In this work the viscosimetry technique was used to evaluate the rheological characteristics of ceramic suspensions prepared with a LZSA (Li2O-ZrO2-SiO2-Al2O3) glass. From the rheological characterization it was possible to establish optimized conditions of solid fraction, dispersant, organic monomers and foaming agent for the production of glass-ceramic foams by gelcasting. The resulting foams were subjected to heattreatments at 200-500ºC/60 min, for degradation of organics and at 950ºC/60 min for sintering and crystallization. With the obtained porous ceramic bodies linear thermal shrinkage, apparent density and mechanical strength measurements as well as microstructural analysis were performed. The adaptation of the rheological characteristics of the LZSA parent glass powder with the gelcasting processing technique allowed the production of ceramic foams with high open and interconnected porosity (>90%) with good thermal stability and with mechanical strength suitable for the production of porous ceramics.Neste trabalho, a técnica de viscosimetria foi utilizada para avaliar as características reológicas de suspensões preparadas com precursor vitrocerâmico do sistema LZSA (Li2O-ZrO2-SiO2-Al2O3). A partir da caracterização reológica, foi possível estabelecer condições composicionais adequadas de fração de sólidos, dispersante e monômeros orgânicos. A quantidade de agente espumante para produção de espumas vitrocerâmicas por gelcasting foi determinada pela variação volumétrica após agitação. As espumas resultantes foram submetidas a tratamentos térmicos no intervalo de temperatura compreendido entre 200 e 500ºC/60 min, para degradação da matéria orgânica e a 950ºC/60 min para sinterização e cristalização. Com os corpos cerâmicos porosos foram realizadas medidas de retração térmica, densidade aparente, análise microestrutural e resistência mecânica. A adequação das características reológicas do precursor LZSA por gelcasting permitiu a produção de espumas com elevada porosidade (> 90%) aberta e interconectada com boa estabilidade térmica e com resistência mecânica compatível com cerâmicas [email protected]@[email protected]@emc.ufsc.brUniversidade Federal de Santa Catarina Departamento de Engenharia Mecânica Programa de Pós-Graduação em Ciência e Engenharia de MateriaisCentro Universitário Barriga Verde - UNIBAVEUniversidade Federal de São Paulo (UNIFESP) Departamento de Ciência e TecnologiaUNIFESP, Depto. de Ciência e TecnologiaSciEL

Mechanical and structural assessment of laboratory- and field-compacted asphalt mixtures

Compaction forms an integral part in the formation of the aggregate orientation and structure of an asphalt mixture and therefore has a profound influence on its final volumetric and mechanical performance. This article describes the influence of various forms of laboratory (gyratory, vibratory and slab-roller) and field compaction on the internal structure of asphalt specimens and subsequently on their mechanical properties, particularly stiffness and permanent deformation. A 2D image capturing and image analysis system has been used together with alternative specimen sizes and orientations to quantify the internal aggregate structure (orientation and segregation) for a range of typically used continuously graded asphalt mixtures. The results show that in terms of aggregate orientation, slab-compacted specimens tend to mimic field compaction better than gyratory and vibratory compaction. The mechanical properties of slab-compacted specimens also tend to be closer to that of field cores. However, the results also show that through careful selection of specimen size, specimen orientation and compaction variables, even mould-based compaction methods can be utilised with particular asphalt mixtures to represent field-compacted asphalt mixtures

Influence of a low magnetic field on the thermal diffusivity of Bi-2212

The thermal diffusivity of a Bi-2212 polycrystalline sample has been measured under a 1T magnetic field applied perpendicularly to the heat flux. The magnetic contribution to the heat carrier mean free path has been extracted and is found to behave as a simple power law. This behavior can be attributed to a percolation process of electrons in the vortex lattice created by the magnetic field.Comment: 10 pages, 3 figures; to be published in Phys. Rev.

Field-Induced Magnetization Steps in Intermetallic Compounds and Manganese Oxides: The Martensitic Scenario

Field-induced magnetization jumps with similar characteristics are observed at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even the existence- of these jumps depends critically on the magnetic field sweep rate used to record the data. It is proposed that, for both compounds, the martensitic character of their antiferromagnetic-to-ferromagnetic transitions is at the origin of the magnetization steps.Comment: 4 pages,4 figure

Magnetic states of granular layered CoFe-Al\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e

The granular layered magnetic system Co80Fe20(t)/Al2 O3 (3 nm), where the Co80Fe20 layers of nominal thickness t form separate, almost spherical magnetic granules of typical diameter 2-3 nm between the Al2O3 spacers, was studied. We discuss measurements of the dc and ac magnetic susceptibility χ for 1 n

Green functions for generalized point interactions in 1D: A scattering approach

Recently, general point interactions in one dimension has been used to model a large number of different phenomena in quantum mechanics. Such potentials, however, requires some sort of regularization to lead to meaningful results. The usual ways to do so rely on technicalities which may hide important physical aspects of the problem. In this work we present a new method to calculate the exact Green functions for general point interactions in 1D. Our approach differs from previous ones because it is based only on physical quantities, namely, the scattering coefficients, $R$ and $T$, to construct $G$. Renormalization or particular mathematical prescriptions are not invoked. The simple formulation of the method makes it easy to extend to more general contexts, such as for lattices of $N$ general point interactions; on a line; on a half-line; under periodic boundary conditions; and confined in a box.Comment: Revtex, 9 pages, 3 EPS figures. To be published in PR