Entropy in Spin Foam Models: The Statistical Calculation

Recently an idea for computing the entropy of black holes in the spin foam formalism has been introduced. Particularly complete calculations for the three dimensional euclidean BTZ black hole were done. The whole calculation is based on observables living at the horizon of the black hole universe. Departing from this idea of observables living at the horizon, we now go further and compute the entropy of BTZ black hole in the spirit of statistical mechanics. We compare both calculations and show that they are very interrelated and equally valid. This latter behaviour is certainly due to the importance of the observables.Comment: 11 pages, 1 figur

Towards a spin foam model description of black hole entropy

We propose a way to describe the origin of black hole entropy in the spin foam models of quantum gravity. This stimulates a new way to study the relation of spin foam models and loop quantum gravity.Comment: 5 pages, 1 figur

Measurements and Information in Spin Foam Models

We present a problem relating measurements and information theory in spin foam models. In the three dimensional case of quantum gravity we can compute probabilities of spin network graphs and study the behaviour of the Shannon entropy associated to the corresponding information. We present a general definition, compute the Shannon entropy of some examples, and find some interesting inequalities.Comment: 15 pages, 3 figures. Improved versio

Supernova search at intermediate z. I. Spectroscopic analysis

We study 8 supernovae discovered as part of the International Time Programme (ITP) project ``Omega and Lambda from Supernovae and the Physics of Supernova Explosions'' at the European Northern Observatory (ENO). The goal of the project is to increase the sample of intermediate redshift (0.1<z<0.4) SNe Ia for testing properties of SNe Ia along z and for enlarging the sample in the Hubble diagram up to large z.Comment: 2 pages, 2 figures, 1 table, to appear in ``1604-2004: Supernovae as Cosmological Lighthouses'', (extended text upon request

56Ni dredge-up in the type IIp Supernova 1995V

We present contemporary infrared and optical spectra of the plateau type II SN 1995V in NGC 1087 covering four epochs, approximately 22 to 84 days after shock breakout. The data show, for the first time, the infrared spectroscopic evolution during the plateau phase of a typical type II event. In the optical region P Cygni lines of the Balmer series and of metals lines were identified. The infrared (IR) spectra were largely dominated by the continuum, but P Cygni Paschen lines and Brackett gamma lines were also clearly seen. The other prominent IR features are confined to wavelengths blueward of 11000 \AA and include Sr II 10327, Fe II 10547, C I 10695 and He I 10830 \AA. We demonstrate the presence of He I 10830 \AA on days 69 and 85. The presence of this line at such late times implies re-ionisation. A likely re-ionising mechanism is gamma-ray deposition following the radioactive decay of 56Ni. We examine this mechanism by constructing a spectral model for the He I 10830 \AA line based on explosion model s15s7b2f of Weaver & Woosley (1993). We find that this does not generate the observed line owing to the confinement of the 56Ni to the central zones of the ejecta. In order to reproduce the He I line, it was necessary to introduce additional upward mixing of the 56Ni, with 10^{-5} of the total nickel mass reaching above the helium photosphere. In addition, we argue that the He I line-formation region is likely to have been in the form of pure helium clumps in the hydrogen envelope.Comment: Accepted for publication in MNRAS, 32 pages including 11 figures (uses psfig.sty - included

Using Head, Heart and Hands to (De)construct Community Development in Tijuana, Mexico

Short-term international service-learning immersions can provide accessible ways for students to experience other countries and cultures, creating the possibility for development of the whole person in a global context. These programs often involve the physical labor of students, through building houses, serving food to migrants, and the like. As Peter-Hans Kolvenbach, S.J. has observed, such service can be valued by the recipient community and for the participating student, and can challenge the mind to change. But how can such programs increase their value proposition in support of the organization’s mission? In other words, how might we employ minds as well as hands and hearts in other ways that promote justice work? This article describes an immersion program, academic course, and community-based research effort forged over a 25-year relationship between Seattle University and Esperanza, a non-governmental organization that focuses on community development, micro finance, and affordable housing in Tijuana, Mexico. Using the Ignatian pedagogical paradigm, a constellation of stakeholders—faculty, staff, students, and community partners—reflect on the partnership and the enhancements to a long-standing collaborative effort. Lessons learned are offered. Ultimately, we conclude that long-term reciprocal benefits can be achieved while also inviting participants to deepen their aspirations for social change in a global context

Biomecánica en la natación

En el último siglo se ha notado de manera significativa el progreso de la técnica de nado en los atletas y esto se debe a estudios científicos que han aportado países como Holanda, Alemania, España y E.U.A, los cuales brindan a los nadadores estudios biomecánicos para mejorar su técnica. Mientras tanto en México, según nuestro conocimiento se proporciona poco apoyo para los atletas que quieren mejorar su rendimiento para llegar a competir en eventos internacionales como las olimpiadas. El presente trabajo tiene como objetivo presentar un proyecto que apoye a la mejora del rendimiento de estos atletas. “Biomecánica en la Natación” se encarga de monitorear y analizar principalmente los movimientos y procesos que hace el cuerpo humano para lograr desplazarse en medio acuático. Consiste en un estudio que analiza y compara en el tiempo la técnica de nado mediante sensores de movimiento, los cuales arrojan simulaciones 3D en forma de avatares y datos de posición y movimiento de diferentes regiones de interés (por sus siglas en inglés ROI, Regions of Interest) en el cuerpo humano. Además, se complementa el análisis de movimiento con el software KINOVEA TM para la medición de datos biométricos de los participantes y el análisis e interpretación de vídeos tomados durante las sesiones de evaluación. También se realizarán tomas de frecuencia cardiaca la cual medirá si existe un aumento o descenso del ritmo. Otra prueba para realizar será la prueba de lactato, la cual se utiliza para determinar la capacidad anaeróbica de un atleta.ITESO, A.C

Total particulate trace element concentrations from bulk aerosol samples collected during the US GEOTRACES EPZT section cruise (R/V Thomas G. Thompson TN303) in the Eastern Tropical Pacific from October to December 2013

Dataset: Total Particulate AerosolsAtmospheric input is important to the biogeochemical cycling of trace metals in the ocean. This dataset provides total particulate trace metal values from bulk aerosols over the Equatorial Pacific along the US GEOTRACES EPTZ transect (TN303) from Peru to Tahiti. This region is characterized as one of the lowest atmospheric deposition regimes in the ocean. Bulk aerosols were collected from the boundary layer (~15 m above sea level) using a high-volume aerosol sampler drawing approximately 1.2 cubic meters of air per minute over Whatman 41 ash-less filter discs. Despite low aerosol loadings, triplicate agreement for most samples was good for Al, Ti, V, Mn, Fe, and Cu. Away from the coast, Cd and Pb values in most samples were close to, or below detection limit. Total digestions were carried out with a combination of hydrochloric acid, nitric acid, hydrofluoric acid, heat and pressure. Total particulate trace metal concentrations were determined at the University of Alaska Fairbanks by inductively couple plasma mass spectrometry (Thermo Element-2) using external calibration curves. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/675632NSF Division of Ocean Sciences (NSF OCE) OCE-1234417, NSF Division of Ocean Sciences (NSF OCE) OCE-145436