Progress report on the relativistic three-particle quantization condition

We describe recent work on the relativistic three-particle quantization condition, generalizing and applying the original formalism of Hansen and Sharpe, and of Brice\~no, Hansen and Sharpe. In particular, we sketch three recent developments: the generalization of the formalism to include K-matrix poles; the numerical implementation of the quantization condition in the isotropic approximation; and ongoing work extending the description of the three-particle divergence-free K matrix beyond the isotropic approximation.Comment: 7 pages, 1 figure, Proceedings of Lattice 201

Proximal methods for stationary mean field games with local couplings

© 2018 Society for Industrial and Applied Mathematics. We address the numerical approximation of mean field games with local couplings. For power-like Hamiltonians, we consider a stationary system and also a system involving density constraints modeling hard congestion effects. For finite difference discretization of the mean field game system developed in [Y. Achdou and I. Capuzzo-Dolcetta, SIAM J. Numer. Anal., 48 (2010), pp. 1136-1162], we follow a variational approach. We prove that the aforementioned schemes can be obtained as the optimality system of suitably defined optimization problems. In order to prove the existence of solutions of the scheme with a variational argument, monotonicity assumptions on the coupling term are not needed, which allows us to recover general existence results proved by Achdou and Capuzzo-Dolcetta. Next, assuming that the coupling term is nondecreasing, the variational problem is cast as a convex optimization problem, for which we study and compare several proximal-type methods. These algorithms have several interesting features, such as global convergence and stability with respect to the viscosity parameter, which can eventually be zero. We assess the performance of the methods via numerical experiments

A fossil assemblage from the mid–late Maastrichtian of Gavdos Island, Greece, provides insights into the pre-extinction pelagic ichthyofaunas of the Tethys

The global body-fossil record of marine ‘fishes’ from the time interval immediately preceding the Cretaceous–Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid–late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil ‘fishes’, which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region

New record of Pachyarmatherium (Cingulata: Pachyarmatheriidae) from the Late Pleistocene in Venezuela

The Falcón state, in northwestern Venezuela, preserves one of the oldest localities documenting human presence on the Americas in association with megafauna remains. One of these localities is the Late Pleistocene Taima-Taima site, which is located in the vicinity of the Caribbean coast. Excavations since the 1960s in the Taima-Taima site, and surroundings, have offered new insights into the faunal assemblages that inhabited this arid coastal savannah region during the Late Pleistocene. Isolated osteoderms collected in recent prospections allow us to report here the presence of the extinct cingulate Pachyarmatherium cf. brasiliense and Pachyarmatherium sp. from the Taima-Taima site, and the new locality Cucuruchú (Las Dunas). The record of these taxa in the Late Pleistocene of the Falcón state increases the known paleodiversity of Cingulata for the region and expands the geographical distribution of the genus, which is poorly known in South America

Study of an iterative resource allocation technique to minimize machine completion times in a distributed computing system

Heterogeneous computing (HC) is the coordinated use of different types of machines, networks, and interfaces to maximize the combined performance and/or cost effectiveness. Heuristics for allocating resources in an HC system have different optimization criteria. A common optimization criterion is to minimize the completion time of the last to finish machine (makespan). In some environments, it is useful to minimize the finishing times of the other machines in the system, i.e., those machines that are not the last to finish. Consider a production environment where a set of known tasks are to be mapped to resources off-line before execution begins. In this study, we present an "iterative" approach for decreasing the finishing time of each machine in a given resource allocation, by repeatedly running a mapping heuristic to minimize makespan on all machines and then the non-makespan machines; i.e., ignoring the current makespan machine and the tasks assigned to it. This work identifies heuristics that can offer improvements in the completion time of non-makespan machines using this "iterative" approach

La NAIRU y el problema de la regresión inversa

En este artículo se efectúa una reseña de la evolución histórica del concepto Tasa de Desempleo No Aceleradora de la Inflación (TDNAI o NAIRU, por su acrónimo en inglés). Se revisan algunos problemas metodológicos que enfrentan quienes se proponen estimar esta variable, y principalmente se demuestra que los cálculos de una virtual nairu a partir de la regresión muestral directa de ?t en función de ut siempre son sesgados debido a que el grado de asociación lineal entre ambas variables no es perfecta. Adicionalmente se demuestra que, aun soslayando los problemas examinados, la evidencia empírica cuestiona severamente la pertinencia de la nairu como guía para la política monetaria o como instrumento para el pronóstico de la tasa de inflación

Yacimiento paleontológico de Taima-Taima. “Una ventana a la última Edad de Hielo en la costa caribeña”

El yacimiento de Taima-Taima, ubicado en la costa caribeña de Venezuela, es un sitio de referencia para el estudio de los primeros pobladores de las Américas. Luego de las primeras excavaciones sistemáticas realizadas en el lugar en la década de 1960, abundantes restos de megafauna y inequívocas evidencias antrópicas fueron encontradas. El ambiente sedimentario ha sido referenciado como un antiguo manantial, y dataciones absolutas le asigan al sitio una edad comprendida entre los 9.650 ± 80 y 14.440 ± 435 años de antigüedad; sustentándose así la teoría de que el paleoindio de la región usó estos bebederos naturales para acechar y cazar grandes mega-mamíferos. Una reseña histórica del yacimiento de Taima-Taima es ofrecida, apuntalando la importancia de carácter patrimonial, histórico y científico del lugar.The Taima-Taima deposit, located on the Caribbean coast of Venezuela, is a reference site for the study of the first settlers of the Americas. After the first systematic excavations carried out on the site in the 1960s, abundant remains of megafauna and unequivocal anthropic evidence were found. The sedimentary environment has been referenced as an ancient spring, and absolute dates give the site an age between 9,650 ± 80 and 14,440 ± 435 years old; thus sustaining the theory that the Paleoindian in the region used these natural drinking troughs to stalk and hunt large mega-mammals. A historical review of the Taima-Taima site is offered, underlining the importance of heritage, historical and scientific character of the place

La NAIRU y el problema de la regresión inversa

En este artículo se efectúa una reseña de la evolución histórica del concepto Tasa de Desempleo No Aceleradora de la Inflación (tdnai o nairu, por su acrónimo en inglés). Se revisan algunos problemas metodológicos que enfrentan quienes se proponen estimar esta variable, y principalmente se demuestra que los cálculos de una virtual nairu a partir de la regresión muestral directa de ?t en función de ut siempre son sesgados debido a que el grado de asociación lineal entre ambas variables no es perfecta. Adicionalmente se demuestra que, aun soslayando los problemas examinados, la evidencia empírica cuestiona severamente la pertinencia de la nairu como guía para la política monetaria o como instrumento para el pronóstico de la tasa de inflación