Is the brick-wall model unstable for a rotating background?

The stability of the brick wall model is analyzed in a rotating background. It is shown that in the Kerr background without horizon but with an inner boundary a scalar field has complex-frequency modes and that, however, the imaginary part of the complex frequency can be small enough compared with the Hawking temperature if the inner boundary is sufficiently close to the horizon, say at a proper altitude of Planck scale. Hence, the time scale of the instability due to the complex frequencies is much longer than the relaxation time scale of the thermal state with the Hawking temperature. Since ambient fields should settle in the thermal state in the latter time scale, the instability is not so catastrophic. Thus, the brick wall model is well defined even in a rotating background if the inner boundary is sufficiently close to the horizon.Comment: Latex, 17 pages, 1 figure, accepted for publication in Phys. Rev.

Efecto de extractos de hojas y frutos de Schinus molle sobre la estabilidad oxidativa de aceites mediante oxidación acelerada

The most highly recommended oils for the diet are those which are rich in unsaturated fatty acids. However, the presence of these components in the oils is related to oxidation, which can be determined by the induction period. Further safety and the prolongation of the storage period for such oils can be achieved by the addition of efficient antioxidants, which today are preferably from natural sources. In order to contribute to the related research, the main objective of this study was to evaluate the efficacy of Schinus molle extracts compared to synthetic antioxidants (BHT) in delaying the oxidation of some vegetable oils. The results of the present study showed that the fruit and leaf extracts of Schinus molle presented activities and potential for being used as antioxidants in vegetable oils based on the tested methods (DPPH and ABTS). The extracts were also characterized as containing phenolic compounds by the Folin Ciocalteau method and by high performance liquid chromatography (HPLC). The action of the extracts as natural antioxidants was proven in the vegetal oils of chia (Salvia hispanica) and peanut (Arachis hypogaea) by the Rancimat method. It was observed that the oils increased their resistance to oxidation when incorporated with the extracts of Schinus molle, and the extract from the leaves increased the induction period of peanut oil by more than three hours (from 19.5 to 22.9 hours) with an extract concentration of 2.5%. The fruit extract was more efficient in delaying the oxidation of chia oil, prolonging its induction period by more than one hour with a concentration of 2.5% (from 3.1 to 4.3 hours). According to the results, the extracts of Schinus molle have favorable properties for possible use as an additive which inhibits the oxidation process of the tested vegetables oils.Los aceites más recomendados para la dieta son los ricos en ácidos grasos insa­turados. Sin embargo, la presencia de estos componentes está relacionada con la oxidación del aceite, que puede determinarse por el período de inducción. La seguridad adicional de tales aceites y la prolongación del almacenamiento se pueden lograr mediante la adición de antioxidantes eficientes, que hoy en día se prefieren los provenientes de fuentes naturales. Para contribuir con estas investigaciones, el objetivo principal de este estudio fue evaluar la eficacia de los extractos de Schinus molle en comparación con el antioxidante sintético BHT, para retrasar la oxidación de algunos aceites vegetales. Los resultados del presente estudio mostraron que los extractos de frutas y hojas de Schinus molle presentan potencial para ser utilizados como antioxidan­tes en aceites vegetales, presentando actividades basadas en métodos probados, DPPH y ABTS. Los extrac­tos también se caracterizaron por la presencia de compuestos fenólicos determinados mediante el método de Folin Ciocalteau y por cromatografía líquida de alta resolución (HPLC). La acción de los extractos como antioxidantes naturales se evidenció en aceites vegetales de chía (Salvia hispanica) y maní (Arachis hypogaea) por el método Rancimat. Se observó que los aceites aumentan la resistencia a la oxidación cuando se le incor­poran extractos de Schinus molle, aumentando el periodo de inducción en más de tres horas (de 19,5 a 22,9 horas) del aceite de cacahuete con una concentración de extracto del 2,5%. El extracto de fruta fue más efi­ciente en retrasar la oxidación del aceite de chia, prolongando el período de inducción de este aceite en más de una hora con una concentración del 2,5% (de 3,1 a 4,3 horas). De acuerdo con los resultados, los extractos de Schinus molle tienen propiedades favorables para un posible uso como un aditivo inhibidor del proceso de oxidación de los aceites vegetales ensayados

Study of Effect on Teeth of Intermittent Fluoridation of a Community Water Supply

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67913/2/10.1177_00220345530320011601.pd

Carbohydrate intake prior to oral glucose tolerance testing

With the emergence of glycated hemoglobin as a diagnostic test for diabetes, oral glucose tolerance tests (OGTTs) have become rare in endocrinology practice. As they have moved out of favor, the importance of patient instructions on preparation prior to OGTT has faded from memory. Decades-old literature, well-known to endocrinologists a generation ago, emphasized the importance of carbohydrate intake prior to OGTT. In this expert endocrine consult, we discuss an OGTT performed in a research setting without adequate carbohydrate intake at the evening meal prior to the OGTT. The resultant elevated plasma glucose levels at 1-hour and 2-hours mimicked the loss of first-phase insulin release seen in early type 1 and type 2 diabetes. With clinical concern that the research participant had evolving type 1 or type 2 diabetes, the volunteer was subjected to additional testing and experienced anxiety. Repeat OGTT was normal after adequate carbohydrate intake (>150 grams/day and >50 grams the evening prior to overnight fast for the study). The physiology of this phenomenon is explored and is likely mediated through beta cell adaptation and alteration in peripheral glucose uptake in response to nutrient exposure. The learnings of decades ago have clearly faded, and this literature should be revisited to ensure that OGTT results are not compromised when ordered for clinical or research purposes

Characterization of neutrino signals with radiopulses in dense media through the LPM effect

We discuss the possibilities of detecting radio pulses from high energy showers in ice, such as those produced by PeV and EeV neutrino interactions. It is shown that the rich radiation pattern structure in the 100 MHz to few GHz allows the separation of electromagnetic showers induced by photons or electrons above 100 PeV from those induced by hadrons. This opens up the possibility of measuring the energy fraction transmitted to the electron in a charged current electron neutrino interaction with adequate sampling of the angular distribution of the signal. The radio technique has the potential to complement conventional high energy neutrino detectors with flavor information.Comment: 5 pages, 4 ps figures. Submitted to Phys. Rev. Let

The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources

The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.Comment: 24 pages, 13 figure

Shadowing Effects on Vector Boson Production

We explore how nuclear modifications to the nucleon structure functions, shadowing, affect massive gauge boson production in heavy ion collisions at different impact parameters. We calculate the dependence of $Z^0$, $W^+$ and $W^-$ production on rapidity and impact parameter to next-to-leading order in Pb+Pb collisions at 5.5 TeV/nucleon to study quark shadowing at high $Q^2$. We also compare our Pb+Pb results to the $pp$ rapidity distributions at 14 TeV.Comment: 25 pages ReVTeX, 12 .eps figures, NLO included, version accepted for publication in Physical Review

Quantum dynamics of crystals of molecular nanomagnets inside a resonant cavity

It is shown that crystals of molecular nanomagnets exhibit enhanced magnetic relaxation when placed inside a resonant cavity. Strong dependence of the magnetization curve on the geometry of the cavity has been observed, providing evidence of the coherent microwave radiation by the crystals. A similar dependence has been found for a crystal placed between Fabry-Perot superconducting mirrors. These observations open the possibility of building a nanomagnetic microwave laser pumped by the magnetic field

The Effect of Shadowing on Initial Conditions, Transverse Energy and Hard Probes in Ultrarelativistic Heavy Ion Collisions

The effect of shadowing on the early state of ultrarelativistic heavy ion collisions is investigated along with transverse energy and hard process production, specifically Drell-Yan, $J/\psi$, and $\Upsilon$ production. We choose several parton distributions and parameterizations of nuclear shadowing, as well as the spatial dependence of shadowing, to study the influence of shadowing on relevant observables. Results are presented for Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV and Pb+Pb collisions at $\sqrt{s_{NN}} = 5.5$ TeV.Comment: Submitted to Phys. Rev.