Multiple-event probability in general-relativistic quantum mechanics: a discrete model

We introduce a simple quantum mechanical model in which time and space are discrete and periodic. These features avoid the complications related to continuous-spectrum operators and infinite-norm states. The model provides a tool for discussing the probabilistic interpretation of generally-covariant quantum systems, without the confusion generated by spurious infinities. We use the model to illustrate the formalism of general-relativistic quantum mechanics, and to test the definition of multiple-event probability introduced in a companion paper. We consider a version of the model with unitary time-evolution and a version without unitary time-evolutio

Multiple-event probability in general-relativistic quantum mechanics

We discuss the definition of quantum probability in the context of "timeless" general--relativistic quantum mechanics. In particular, we study the probability of sequences of events, or multi-event probability. In conventional quantum mechanics this can be obtained by means of the ``wave function collapse" algorithm. We first point out certain difficulties of some natural definitions of multi-event probability, including the conditional probability widely considered in the literature. We then observe that multi-event probability can be reduced to single-event probability, by taking into account the quantum nature of the measuring apparatus. In fact, by exploiting the von-Neumann freedom of moving the quantum classical boundary, one can always trade a sequence of non-commuting quantum measurements at different times, with an ensemble of simultaneous commuting measurements on the joint system+apparatus system. This observation permits a formulation of quantum theory based only on single-event probability, where the results of the "wave function collapse" algorithm can nevertheless be recovered. The discussion bears also on the nature of the quantum collapse

Unitary Chern-Simons matrix model and the Villain lattice action

We use the Villain approximation to show that the Gross-Witten model, in the weak- and strong-coupling limits, is related to the unitary matrix model that describes U(N) Chern-Simons theory on S^3. The weak-coupling limit corresponds to the q->1 limit of the Chern-Simons theory while the strong-coupling regime is related to the q->0 limit. In the latter case, there is a logarithmic relationship between the respective coupling constants. We also show how the Chern-Simons matrix model arises by considering two-dimensional Yang-Mills theory with the Villain action. This leads to a U(1)^N theory which is the Abelianization of 2d Yang-Mills theory with the heat-kernel lattice action. In addition, we show that the character expansion of the Villain lattice action gives the q deformation of the heat kernel as it appears in q-deformed 2d Yang-Mills theory. We also study the relationship between the unitary and Hermitian Chern-Simons matrix models and the rotation of the integration contour in the corresponding integrals.Comment: 17 pages, Minor corrections to match the published versio

Tsunami hazard assessment in the southern Colombian Pacific basin and a proposal to regenerate a previous barrier island as protection

ABSTRACT: In this study, the tsunami hazard posed to 120 000 inhabitants of Tumaco (Colombia) is assessed, and an evaluation and analysis of regenerating the previous El Guano Island for tsunami protection is conducted. El Guano Island was a sandy barrier island in front of the city of Tumaco until its disappearance during the tsunami of 1979; the island is believed to have played a protective role, substantially reducing the scale of the disaster. The analysis is conducted by identifying seismotectonic parameters and focal mechanisms of tsunami generation in the area, determining seven potential generation sources, applying a numerical model for tsunami generation and propagation, and evaluating the effect of tsunamis on Tumaco. The results show that in the current situation, this area is vulnerable to impact and flooding by tsunamis originating nearby. El Guano Island was found to markedly reduce flood levels and the energy flux of tsunami waves in Tumaco during the 1979 tsunami. By reducing the risk of flooding due to tsunamis, the regeneration and morphological modification of El Guano Island would help to protect Tumaco

Concordancia entre los modelos de SCORE y Framingham y las ecuaciones AHA/ACC como evaluadores de riesgo cardiovascular

ResumenObjetivoDiferentes modelos de evaluación de riesgo cardiovascular están actualmente en uso en Colombia. El objetivo de este estudio es analizar la concordancia entre las ecuaciones AHA/ACC 2013, SCORE y Framingham ajustado, así como el impacto de usar una u otra en la cantidad de pacientes clasificados como de alto riesgo y en la cantidad de pacientes que requerirían manejo farmacológico.MétodosSe evaluaron 800 pacientes entre 40 y 74 años, de la clínica de prevención primaria del Hospital militar Central en Bogotá (Colombia), libres de eventos cardiovasculares. Se estimaron el riesgo a 10 años de enfermedad arterioesclerótica cardiovascular según las ecuaciones propuestas por las guías AHA/ACC 2013, el riesgo de muerte cardiovascular según la función SCORE de la guía europea y el riesgo coronario según la función de Framingham ajustada, recomendada por la guía colombiana. Se consideró como indicación de manejo farmacológico un cálculo de riesgo AHA/ACC o Framingham ajustado>7,5%. Un riesgo de Framingham>20% o SCORE>5% definía el riesgo alto.ResultadosSegún el Framingham había un 5,9% de pacientes de alto riesgo, según las ecuaciones de SCORE para países de bajo riesgo un 18,7% y según las ecuaciones de SCORE para países de alto riesgo, un 31,2%. El coeficiente Kappa mostró baja concordancia entre Framingham ajustado y cada una de las ecuaciones de SCORE (0,28 y 0,22 respectivamente). Según las recomendaciones de la guía AHA/ACC, el tratamiento hipolipemiante estaría indicado en un 40,8% de los pacientes, frente a un 50,6% según la guía colombiana (Framingham ajustado). El coeficiente kappa fue de 0,5735.ConclusionesEn la actualidad existe pobre acuerdo entre las diferentes escalas de evaluación del riesgo cardiovascular usadas en Colombia, hecho que conlleva incertidumbre para la toma de decisiones terapéuticas. Los datos de este estudio demuestran la necesidad de validar los modelos de SCORE y AHA/ACC en Colombia y Latinoamérica.AbstractMotivationIn Colombia, different models of cardiovascular risk assessment are currently being used. The motivation of this study is to analyse the concordance between the ACC/AHA 2013 equation, SCORE and adjusted Framingham, as well as the impact of using one or another in the amount of patients classified as high risk and the amount of patients requiring pharmacological management.Methods800 patients between 40 and 74 years old were assessed, from the primary prevention clinic of the Hospital Militar Central in Bogotá (Colombia), who were free of cardiovascular events. 10-year risk for atherosclerotic vascular disease was estimated according to the equations proposed by ACC/AHA 2013 guides, the risk of cardiovascular death according to the SCORE function of the European guide and the coronary risk according to the adjusted Framingham function recommended by the Colombian guide. The indication of pharmacological management was considered with an ACC/AHA or adjusted Framingham risk of>7.5%. A >20% Framingham or a >5% SCORE risk were considered high risk.ResultsAccording to Framingham there was a 5.9% of high-risk patients, according to SCORE equations for low-risk countries an 18.7% and according to SCORE equations for high-risk countries, a 31.2%. The Kappa coefficient showed a low concordance between adjusted Framingham and each of the SCORE equations (0.28 and 0.22 respectively). According to the ACC/AHA guide recommendations, hypolipidemic treatment would be indicated in 40.8% of patients, versus a 50.6% following the Colombian guide indications (adjusted Framingham). Kappa coefficient was 0.5735.ConclusionsNowadays there is a poor agreement between the different cardiovascular risk assessment scales used in Colombia, thus generating uncertainty when it comes to making therapeutic choices. Data from this study show the need to validate the validate the SCORE and ACC/AHA models in Colombia and Latin America

Encoding dynamics for multiscale community detection: Markov time sweeping for the Map equation

The detection of community structure in networks is intimately related to finding a concise description of the network in terms of its modules. This notion has been recently exploited by the Map equation formalism (M. Rosvall and C.T. Bergstrom, PNAS, 105(4), pp.1118--1123, 2008) through an information-theoretic description of the process of coding inter- and intra-community transitions of a random walker in the network at stationarity. However, a thorough study of the relationship between the full Markov dynamics and the coding mechanism is still lacking. We show here that the original Map coding scheme, which is both block-averaged and one-step, neglects the internal structure of the communities and introduces an upper scale, the `field-of-view' limit, in the communities it can detect. As a consequence, Map is well tuned to detect clique-like communities but can lead to undesirable overpartitioning when communities are far from clique-like. We show that a signature of this behavior is a large compression gap: the Map description length is far from its ideal limit. To address this issue, we propose a simple dynamic approach that introduces time explicitly into the Map coding through the analysis of the weighted adjacency matrix of the time-dependent multistep transition matrix of the Markov process. The resulting Markov time sweeping induces a dynamical zooming across scales that can reveal (potentially multiscale) community structure above the field-of-view limit, with the relevant partitions indicated by a small compression gap.Comment: 10 pages, 6 figure

Darboux coordinates for (first order) tetrad gravity

The Hamiltonian form of the Hilbert action in the first order tetrad formalism is examined. We perform a non-linear field redefinition of the canonical variables isolating the part of the spin connection which is canonically conjugate to the tetrad. The geometrical meaning of the constraints written in these new variables is examined.Comment: 12 pages, Latex. Minor presentation changes and some references added. Version to appear in Classical and Quantum Gravit

Complete Calabi-Yau metrics from Kahler metrics in D=4

In the present work the local form of certain Calabi-Yau metrics possessing a local Hamiltonian Killing vector is described in terms of a single non linear equation. The main assumptions are that the complex $(3,0)$-form is of the form $e^{ik}\widetilde{\Psi}$, where $\widetilde{\Psi}$ is preserved by the Killing vector, and that the space of the orbits of the Killing vector is, for fixed value of the momentum map coordinate, a complex 4-manifold, in such a way that the complex structure of the 4-manifold is part of the complex structure of the complex 3-fold. The link with the solution generating techniques of [26]-[28] is made explicit and in particular an example with holonomy exactly SU(3) is found by use of the linearization of [26], which was found in the context of D6 branes wrapping a holomorphic 1-fold in a hyperkahler manifold. But the main improvement of the present method, unlike the ones presented in [26]-[28], does not rely in an initial hyperkahler structure. Additionally the complications when dealing with non linear operators over the curved hyperkahler space are avoided by use of this method.Comment: Version accepted for publication in Phys.Rev.

How many people with type 2 diabetes fulfil the eligibility criteria for randomized, controlled trials of insulin glargine 300 U/mL in a real-world setting?

Altres ajuts: SanofiRandomized controlled trial (RCT) populations often do not reflect those typically seen in clinical practice. This retrospective, observational cohort study analysed the real-world data of people with type 2 diabetes (T2DM) prescribed basal insulin analogues from electronic medical records (EMRs) in the Explorys database, which includes data from 39 integrated healthcare systems in the United States, to determine how representative selected RCTs investigating insulin glargine 300 U/mL (Gla-300) are of T2DM populations in a real-world setting. Applying eligibility criteria derived from the EDITION 1, 2 and 3 (Gla-300 vs. insulin glargine 100 U/mL [Gla-100]) and BRIGHT (Gla-300 vs. insulin degludec) RCTs, we observed that only 17% (33 345/191 218) of people captured in the real-world database would have been eligible for such trials. Those who were ineligible tended to be older, had more comorbidities and a higher baseline hypoglycaemia rate than the eligible group. Using another large US EMR database (Optum Humedica) as corroboration, we found that 15% (36 285/235 697) would have been eligible to participate in the EDITION/BRIGHT RCTs. Furthermore, only 7% (1734/24 547) would have been eligible for the CONCLUDE (insulin degludec vs. Gla-300) RCT. Our findings remind us of the value of real-world data studies, complementing the results of RCTs, and providing additional insights into groups who would typically be excluded from RCTs