938 research outputs found

    Primordial Black Holes: sirens of the early Universe

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    Primordial Black Holes (PBHs) are, typically light, black holes which can form in the early Universe. There are a number of formation mechanisms, including the collapse of large density perturbations, cosmic string loops and bubble collisions. The number of PBHs formed is tightly constrained by the consequences of their evaporation and their lensing and dynamical effects. Therefore PBHs are a powerful probe of the physics of the early Universe, in particular models of inflation. They are also a potential cold dark matter candidate.Comment: 21 pages. To be published in "Quantum Aspects of Black Holes", ed. X. Calmet (Springer, 2014

    Formation and Propagation of Matter Wave Soliton Trains

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    Attraction between atoms in a Bose-Einstein-Condensate renders the condensate unstable to collapse. Confinement in an atom trap, however, can stabilize the condensate for a limited number of atoms, as was observed with 7Li, but beyond this number, the condensate collapses. Attractive condensates constrained to one-dimensional motion are predicted to form stable solitons for which the attractive interactions exactly compensate for the wave packet dispersion. Here we report the formation or bright solitons of 7Li atoms created in a quasi-1D optical trap. The solitons are created from a stable Bose-Einstein condensate by magnetically tuning the interactions from repulsive to attractive. We observe a soliton train, containing many solitons. The solitons are set in motion by offsetting the optical potential and are observed to propagate in the potential for many oscillatory cycles without spreading. Repulsive interactions between neighboring solitons are inferred from their motion

    Numerical Modeling of the Internal Temperature in the Mammary Gland

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    The microwave thermometry method for the diagnosis of breast cancer is based on an analysis of the internal temperature distribution.This paper is devoted to the construction of a mathematical model for increasing the accuracy of measuring the internal temperature of mammary glands, which are regarded as a complex combination of several components, such as fat tissue, muscle tissue, milk lobules, skin, blood flows, tumor tissue. Each of these biocomponents is determined by its own set of physical parameters. Our numerical model is designed to calculate the spatial distributions of the electric microwave field and the temperature inside the biological tissue. We compare the numerical simulations results to the real medical measurements of the internal temperature.Comment: 8 pages, 4 figure

    HIV subtype and drug resistance patterns among drug naĂŻve persons in Jos, Nigeria

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    To determine HIV-1 subtypes and antiretroviral drug resistance mutations for 16 infected, pregnant women in Jos, Nigeria, part of pol (1040 bp) was amplified from patient PBMC DNA, sequenced andanalyzed. Eight of the samples were subtype G, three were CRF02_AG and 2 were unique recombinant forms (URF) between G and CRF02_AG. The remaining consisted of 3 different strains: one was subtypeC, and the other 2 were unrelated URF. Nearly full-length genome sequences were completed for 6 of the strains: 4 subtype G and 2 CRF02_AG. In the 14 drug-naĂŻve subjects, no primary resistance-associated mutations were found, but secondary mutations were identified in 7 different codons of the gene coding for protease: PR K20I, M36I, L63A/P/V, V82I, L10M/I and I93L. In addition, the K238R mutation was identified in the reverse transcriptase gene of 3 viruses. The PR K20I and M36I mutations occurred in all of the strains, and the L10M and V82I mutations occurred only in subtype G. The mutation, I93L, was carried by subtype C viruses. Two of the women that had prior niverapine treatment, had primary resistance-associated mutations, RT M184V and K103N, archived in their proviral DNA several months after treatment cessation. The study reports a predominance of clade G and CRF02_AG, and provides many more examples of nearly full-length genome sequences for subtype G viruses from Nigeria. The ubiquitous presence of PI secondary resistance-associated mutations, as well as primary resistanceassociatedmutations in 2 previously treated women, underscores the need to ensure adherence compliance to treatment

    The In Vivo Wear Resistance of 12 Composite Resins

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    : The in vivo wear resistance of 12 composite resins were compared with an amalgam control using the Latin Square experimental design. Sixteen edentulous patients wearing specially designed complete dentures formed the experimental population. Materials and Methods : The Michigan Computer Graphics Measurement System was used to digitize the surface of the control and composite resin samples before and after 3-month test periods to obtain wear data. The 12 composite resins selected for this investigation based on their published composite classification types were seven fine particle composites, three blends, and two microfilled composite resins. The Latin Square experimental design was found to be valid with the factor of material being statistically different at the 5% level of significance. Wear was computed as volume loss (mm 3 /mm 2 ), and all of the composites studied had more wear than the amalgam control ( P = .001). Results : After 3 months, the mean (error) of wear of the amalgam was 0.028 (0.006). Means (error) of wear for the 12 composites were ranked from most to least wear by mean wear volume loss. Conclusions : The absence of any relationship between mean wear volume loss and the volume percentage filler was confirmed by the correlation coefficient r = -0.158.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72960/1/j.1532-849X.1992.tb00419.x.pd

    Loneliness, social support and cardiovascular reactivity to laboratory stress

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    Self-reported or explicit loneliness and social support have been inconsistently associated with cardiovascular reactivity (CVR) to stress. The present study aimed to adapt an implicit measure of loneliness, and use it alongside the measures of explicit loneliness and social support, to investigate their correlations with CVR to laboratory stress. Twenty-five female volunteers aged between 18 and 39 years completed self-reported measures of loneliness and social support, and an Implicit Association Test (IAT) of loneliness. The systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) reactivity indices were measured in response to psychosocial stress induced in the laboratory. Functional support indices of social support were significantly correlated with CVR reactivity to stress. Interestingly, implicit, but not explicit, loneliness was significantly correlated with DBP reactivity after one of the stressors. No associations were found between structural support and CVR indices. Results are discussed in terms of validity of implicit versus explicit measures and possible factors that affect physiological outcomes

    Pediatrics

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    OBJECTIVESTo describe the prevalence and secular trends of high weight-for-length among infants (ages, 3\u201323 months) in the biennial US Department of Agriculture Women, Infants, and Children Program and Participants Characteristic (WIC-PC) Survey from 2000 through 2014 (n = 16 927 120).METHODSWeight-for-length was considered to be \u201chigh\u201d if it was 652 SDs above the sex-and age-specific median in the World Health Organization growth standards. Poisson regression was used to calculate adjusted prevalence ratios.RESULTSThe overall prevalence of high weight-for-length increased from 13.4% in 2000 to 14.5% in 2004, remained constant until 2010, and then decreased by >2 percentage points (to 12.3%) through 2014. The prevalence of high weight-for-length was associated with sex (higher among boys), race-ethnicity (highest among American Indians/Alaskan Natives), and with both age (positive) and family income (inverse). The secular trends, however, were fairly similar within categories of these variables. From 2010 to 2014, the prevalence of high weight-for-length decreased in 40 states and 3 (of 5) US territories, with the largest decreases seen in Puerto Rico ( 129 percentage points) and Kentucky ( 127 percentage points), and the largest increase (+2 percentage points) seen in West Virginia.CONCLUSIONSAlthough the current results cannot be considered representative of infants in the populations, the prevalence of a high weight-for-length has decreased among infants in WIC-PC since 2010. These decreases were similar across categories of most characteristics, but there were substantial differences across jurisdictions, possibly reflecting differences in policy and local programs that target maternal and infant health.20162018-01-01T00:00:00ZCC999999/Intramural CDC HHS/United States27965380PMC5359001777

    A new portable vibrator for plaster pouring: effect on the marginal fit at cylinder-abutment

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    OBJECTIVE: The aim of this study was to test a new portable vibrator for plaster pouring (developed for this purpose), comparing the effect of its use on the accuracy of working cast of implant-supported restorations to the conventional vibrator. MATERIAL AND METHODS: From a master cast with 2 implants, 30 transfer moldings were made randomly and divided into three groups: Group I (GI): pouring performed in an outsourced dental laboratory with conventional plaster vibrator (10 casts), Group II (GII): pouring performed in the laboratory of the Federal University of Santa Catarina (UFSC) with conventional plaster vibrator (10 casts) and Group III (GIII): pouring performed with the portable vibrator fabricated for this study (10 casts). The position of the analogue and marginal adaptation of the infrastructure were verified by testing the single screw on the master model and on the working model. The measurement of misfit was blindly performed with a precision microscope and analyzing unit, Quadra-Check 200. The data were statistically analyzed by analysis of variance (ANOVA) and the Holm-Sidak test (α=0.05). RESULTS: Means±standard deviations were as follows: GI: 19.19±4.73 µm; GII: 21.72±5.41 µm; GIII: 13.5±2.39 µm (P<0.05), with GIII significantly lower as compared to the other groups. CONCLUSION: Within the limitations of this study, it was concluded that a greater accuracy of working cast was achieved when a portable vibrator was used for casting molds
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