Thermodynamics of frozen stars

The frozen star is a recent proposal for a non-singular solution of Einstein's equations that describes an ultracompact object which closely resembles a black hole from an external perspective. The frozen star is also meant to be an alternative, classical description of an earlier proposal, the highly quantum polymer model. Here, we show that the thermodynamic properties of frozen stars closely resemble those of black holes: Frozen stars radiate thermally, with a temperature and an entropy that are perturbatively close to those of black holes of the same mass. Their entropy is calculated using the Euclidean-action method of Gibbons and Hawking. We then discuss their dynamical formation by estimating the probability for a collapsing shell of "normal" matter to transition, quantum mechanically, into a frozen star. This calculation followed from a reinterpretation of a transitional region between the Euclidean frozen star and its Schwarzschild exterior as a Euclidean instanton that mediates a phase transition from the Minkowski interior of an incipient Schwarzschild black hole to a microstate of the frozen star interior. It is shown that, up to negligible corrections, the probability of this transition is $e^{-A/4}$, with $A$ being the star's surface area. Taking into account that the dimension of the phase space is $e^{+A/4}$, we conclude that the total probability for the formation of the frozen star is of order unity. The duration of this transition is estimated, which we then use to argue, relying on an analogy to previous results, about the scaling of the magnitude of the off-diagonal corrections to the number operator for the Hawking-like particles. Such scaling was shown to imply that the corresponding Page curve indeed starts to go down at about the Page time, as required by unitarity

Collagen-Binding Peptidoglycans Inhibit MMP Mediated Collagen Degradation and Reduce Dermal Scarring

Scarring of the skin is a large unmet clinical problem that is of high patient concern and impact. Wound healing is complex and involves numerous pathways that are highly orchestrated, leaving the skin sealed, but with abnormal organization and composition of tissue components, namely collagen and proteoglycans, that are then remodeled over time. To improve healing and reduce or eliminate scarring, more rapid restoration of healthy tissue composition and organization offers a unique approach for development of new therapeutics. A synthetic collagen-binding peptidoglycan has been developed that inhibits matrix metalloproteinase-1 and 13 (MMP-1 and MMP-13) mediated collagen degradation. We investigated the synthetic peptidoglycan in a rat incisional model in which a single dose was delivered in a hyaluronic acid (HA) vehicle at the time of surgery prior to wound closure. The peptidoglycan treatment resulted in a significant reduction in scar tissue at 21 days as measured by histology and visual analysis. Improved collagen architecture of the treated wounds was demonstrated by increased tensile strength and transmission electron microscopy (TEM) analysis of collagen fibril diameters compared to untreated and HA controls. The peptidoglycan's mechanism of action includes masking existing collagen and inhibiting MMP-mediated collagen degradation while modulating collagen organization. The peptidoglycan can be synthesized at low cost with unique design control, and together with demonstrated preclinical efficacy in reducing scarring, warrants further investigation for dermal wound healing

Natural history of rotavirus infection in the children of Santa Maria Cauque

Artículo científico -- Uiversidad de Costa Rica, Instituto de Investigaciones en Salud. 1983A prospective observation of 45 cohort children from birth to three years of age permitted the collection of 5689 weekly stool specimens, along with frequent morbidity, dietary and growth data. Specimens tested by the EtISA showed that all children became infected with rotaviruses during the first three years of life, many repeatedly. The overall rotavirus incidence was 10.6 per 100 child-months (or 1.3 infections per child per year). Rotaviruses exhibited a high pathogenic potential estimated in 65%, but only about 10% of all diarrheas appeared associated with them. Rotaviruses occurred throughout the year but clustering was evident in August through December, with epidemics of greater severity in particular months of certain years. During outbreaks, from a third to one half of all children became infected with rotaviruses in a given month. This and the frequent association of rotaviruses with other enteric agents ;(34 %) suggest that fecal-oral transmission is the main source of infection, a net result of the prevailing low socioeconomic level in the village setting.Universidad de Costa Rica, Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Acinetobacter baumannii at a Tertiary-Care Teaching Hospital in Jerusalem, Israel

In a retrospective 10-year analysis of 3,536 patient-unique isolates, Acinetobacter baumannii imipenem susceptibility declined from 98.1 (1990) to 64.1% (2000), and ciprofloxacin susceptibility decreased from 50.5 to 13.1%. Imipenem median zone diameters decreased from 27.7 (1997) to 18.8 mm (2000). No outbreaks were detected. Two clusters were identified for 41 strains genotyped by pulsed-field gel electrophoresis, but imipenem resistance was not clonal

Epidemiology of rotaviruses in a cohort of 45 Guatemalan Mayan Indian children observed from birth to the age of three years

Artículo científico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1983. Este artículo es privado debido a limitaciones de derechos de autor.Chort of 45 children was observed from birth to three years of age in their natural ecosystem to determine patterns of infection, morbidity, and growth. Data from enzyme-linked immunosorbent assay analysis for rotavirus of 5,891 extracts (kept frozen since 1964-1969) of weekly fecal specimens were compared against growth, morbidity, and specimen data files, permitting a retrospective description of the epidemiology of rotavirus infection in the cohort. Rotavirus infections were uncommon in the first months of life in intensively breast-fed infants. Infection increased with age to reach a maximal rate in the six- to 18-month age period. While there was a high incidence of diarrhea in the cohort, rotavirus was associated with only 10% of such episodes. The incidence of rotavirus infection was 1.2 episodes per child-year, and the incidence of rotavirus-associated diarrhea was 0.8 episodes per child-year. Serious outbreaks of rotavirus generally occurred from September through December, with as many as one-half of the children becoming infected. Repeated rotavirus infection was a common phenomenon.Organización Panamericana de la SaludUniversidad de Costa Rica. Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

EUROGRAPHICS Workshop on Sketch-Based Interfaces and Modeling (2004)

This paper presents a smart interface that automatically extracts and refines pen strokes from images of hand drawn sketches. The interface allows users to digitize hand-drawn material such sketches of flowcharts, cartoons or other pen based drawings and automatically isolate and refine the individual strokes making up the sketch. First, we present a method for extracting pen strokes based on learned constraints on curves. The approach consists of using a training set that shows good examples of curves and how a user would draw them. Given an image of a hand-drawn sketch, the system selects the pen stroke that is most statistically consistent with the examples in the training set and ranks the others based on their likelihood. Users can keep the selected candidate or they may scroll through the other top candidates to select a preferred solution. Second, we present an overview of our refinement procedure and its application on the extracted pen strokes. Using the same database of examples, the extracted pen stroke is refined to make it 'look' more like those in the database