An Optical Readout TPC (O-TPC) for Studies in Nuclear Astrophysics With Gamma-Ray Beams at HIgS

We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO2(80%) + N2(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic gamma-ray beams at the High Intensity Gamma Source (HIgS) facility. The O-TPC has a sensitive target-drift volume of 30x30x21 cm^3. Ionization electrons drift towards a double parallel grid avalanche multiplier, yielding charge multiplication and light emission. Avalanche induced photons from N2 emission are collected, intensified and recorded with a Charge Coupled Device (CCD) camera, providing two-dimensional track images. The event's time projection (third coordinate) and the deposited energy are recorded by photomultipliers and by the TPC charge-signal, respectively. A dedicated VME-based data acquisition system and associated data analysis tools were developed to record and analyze these data. The O-TPC has been tested and calibrated with 3.183 MeV alpha-particles emitted by a 148Gd source placed within its volume with a measured energy resolution of 3.0%. Tracks of alpha and 12C particles from the dissociation of 16O and of three alpha-particles from the dissociation of 12C have been measured during initial in-beam test experiments performed at the HIgS facility at Duke University. The full detection system and its performance are described and the results of the preliminary in-beam test experiments are reported.Comment: Supported by the Richard F. Goodman Yale-Weizmann Exchange Program, ACWIS, NY, and USDOE grant Numbers: DE-FG02-94ER40870 and DE-FG02-97ER4103

Electronic structure of superconducting graphite intercalate compounds: The role of the interlayer state

Although not an intrinsic superconductor, it has been long--known that, when intercalated with certain dopants, graphite is capable of exhibiting superconductivity. Of the family of graphite--based materials which are known to superconduct, perhaps the most well--studied are the alkali metal--graphite intercalation compounds (GIC) and, of these, the most easily fabricated is the C${}_8$K system which exhibits a transition temperature $\bm{T_c\simeq 0.14}$K. By increasing the alkali metal concentration (through high pressure fabrication techniques), the transition temperature has been shown to increase to as much as $\bm 5$K in C${}_2$Na. Lately, in an important recent development, Weller \emph{et al.} have shown that, at ambient conditions, the intercalated compounds \cyb and \cca exhibit superconductivity with transition temperatures $\bm{T_c\simeq 6.5}$K and $\bm{11.5}$K respectively, in excess of that presently reported for other graphite--based compounds. We explore the architecture of the states near the Fermi level and identify characteristics of the electronic band structure generic to GICs. As expected, we find that charge transfer from the intercalant atoms to the graphene sheets results in the occupation of the $\bm\pi$--bands. Yet, remarkably, in all those -- and only those -- compounds that superconduct, we find that an interlayer state, which is well separated from the carbon sheets, also becomes occupied. We show that the energy of the interlayer band is controlled by a combination of its occupancy and the separation between the carbon layers.Comment: 4 Figures. Please see accompanying experimental manuscript "Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca" by Weller et a

Maternal Environmental Contribution to Adult Sensitivity and Resistance to Obesity in Long Evans Rats

The OLETF rat is an animal model of early onset hyperphagia induced obesity, presenting multiple pre-obese characteristics during the suckling period. In the present study, we used a cross-fostering strategy to assess whether interactions with obese dams in the postnatal environment contributed to the development of obesity.On postnatal Day (PND)-1 OLETF and control LETO pups were cross-fostered to same or opposite strain dams. An independent ingestion test was performed on PND11 and a nursing test on PND18. Rats were sacrificed at weaning or on PND90, and plasma leptin, insulin, cholesterol, triglycerides and alanine aminotransferase (ALT) were assayed. Fat pads were collected and weighed and adipocyte size and number were estimated. Body weight and intake, as well as the estrous cycle of the female offspring were monitored.During the suckling period, the pups' phenotype was almost completely determined by the strain of the mother. However, pups independently ingested food according to their genotype, regardless of their actual phenotype. At adulthood, cross fostered males of both strains and LETO females were affected in regard of their adiposity levels in the direction of the foster dam. On the other hand, OLETF females showed almost no alterations in adiposity but were affected by the strain of the dams in parameters related to the metabolic syndrome. Thus, OLETF females showed reduced liver adiposity and circulating levels of ALT, while LETO females presented a disrupted estrous cycle and increased cholesterol and triglycerides in the long term.The present study provides further support for the early postnatal environment playing a sex-divergent role in programming later life phenotype. In addition, it plays a more central role in determining the functioning of mechanisms involved in energy balance that may provide protection from or sensitivity to later life obesity and pathologies related to the metabolic syndrome

Detection of rubella antibodies in human serum by the indirect fluorescent antibody technique

Antibodies for rubella virus were detected in human serum and titrated by the indirect method of immunofluorescence using a chronically infected, continuous line of monkey kidney cells as antigen. Positive reactions were obtained with convalescent or post-exposure specimens while acute sera and those from unexposed individuals were negative.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41678/1/705_2005_Article_BF01253854.pd

Cosmological parameters constraints from galaxy cluster mass function measurements in combination with other cosmological data

We present the cosmological parameters constraints obtained from the combination of galaxy cluster mass function measurements (Vikhlinin et al., 2009a,b) with new cosmological data obtained during last three years: updated measurements of cosmic microwave background anisotropy with Wilkinson Microwave Anisotropy Probe (WMAP) observatory, and at smaller angular scales with South Pole Telescope (SPT), new Hubble constant measurements, baryon acoustic oscillations and supernovae Type Ia observations. New constraints on total neutrino mass and effective number of neutrino species are obtained. In models with free number of massive neutrinos the constraints on these parameters are notably less strong, and all considered cosmological data are consistent with non-zero total neutrino mass \Sigma m_\nu \approx 0.4 eV and larger than standard effective number of neutrino species, N_eff \approx 4. These constraints are compared to the results of neutrino oscillations searches at short baselines. The updated dark energy equation of state parameters constraints are presented. We show that taking in account systematic uncertainties, current cluster mass function data provide similarly powerful constraints on dark energy equation of state, as compared to the constraints from supernovae Type Ia observations.Comment: Accepted for publication in Astronomy Letter

Knowledge and attitudes of primary healthcare patients regarding population-based screening for colorectal cancer

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to assess the extent of knowledge of primary health care (PHC) patients about colorectal cancer (CRC), their attitudes toward population-based screening for this disease and gender differences in these respects.</p> <p>Methods</p> <p>A questionnaire-based survey of PHC patients in the Balearic Islands and some districts of the metropolitan area of Barcelona was conducted. Individuals between 50 and 69 years of age with no history of CRC were interviewed at their PHC centers.</p> <p>Results</p> <p>We analyzed the results of 625 questionnaires, 58% of which were completed by women. Most patients believed that cancer diagnosis before symptom onset improved the chance of survival. More women than men knew the main symptoms of CRC. A total of 88.8% of patients reported that they would perform the fecal occult blood test (FOBT) for CRC screening if so requested by PHC doctors or nurses. If the FOBT was positive and a colonoscopy was offered, 84.9% of participants indicated that they would undergo the procedure, and no significant difference by gender was apparent. Fear of having cancer was the main reason for performance of an FOBT, and also for not performing the FOBT, especially in women. Fear of pain was the main reason for not wishing to undergo colonoscopy. Factors associated with reluctance to perform the FOBT were: <b><it>(i) </it></b>the idea that that many forms of cancer can be prevented by exercise and, <b><it>(ii) </it></b>a reluctance to undergo colonoscopy if an FOBT was positive. Factors associated with reluctance to undergo colonoscopy were: <b><it>(i) </it></b>residence in Barcelona, <b><it>(ii) </it></b>ignorance of the fact that early diagnosis of CRC is associated with better prognosis, <b><it>(iii) </it></b>no previous history of colonoscopy, and <b><it>(iv) </it></b>no intention to perform the FOBT for CRC screening.</p> <p>Conclusion</p> <p>We identified gaps in knowledge about CRC and prevention thereof in PHC patients from the Balearic Islands and the Barcelona region of Spain. If fears about CRC screening, and CRC per se, are addressed, and if it is emphasized that CRC is preventable, participation in CRC screening programs may improve.</p

Dark solitons in atomic Bose-Einstein condensates: from theory to experiments

This review paper presents an overview of the theoretical and experimental progress on the study of matter-wave dark solitons in atomic Bose-Einstein condensates. Upon introducing the general framework, we discuss the statics and dynamics of single and multiple matter-wave dark solitons in the quasi one-dimensional setting, in higher-dimensional settings, as well as in the dimensionality crossover regime. Special attention is paid to the connection between theoretical results, obtained by various analytical approaches, and relevant experimental observations.Comment: 82 pages, 13 figures. To appear in J. Phys. A: Math. Theor