373 research outputs found

    Biochemical correlates of cardiac hypertrophy. I. Experimental model; changes in heart weight, RNA content, and nuclear RNA polymerase activity

    Get PDF
    Cardiac hypertrophy occurred in mature rats after producing supravalvular aortic stenosis with a specially designed silver clip. For 2 weeks following this procedure, heart weight, body weight, and RNA content of the myocardium were serially determined. Heart weight and RNA content increased within 24 hours of aortic banding, reaching a maximal level in 2 days and remaining elevated during the 2 weeks of observation. Nuclei were isolated and purified from heart muscle homogenates, and changes in RNA polymerase activity following aortic banding were determined. The nearest neighbor frequency of the bases of the RNA synthesized by the polymerase from nuclear preparations was identical in both the banded animals and the sham-operated controls. Both groups could thus be compared on the basis of the enzyme assay. RNA polymerase activity in nuclei from the hearts of banded rats rose rapidly when compared with the activity in sham-operated rats; peak values were reached on the second day, the earliest detectable change being around 12 hours. The increase in RNA polymerase activity represents one of the earliest biochemical events that take place in the myocardium following aortic banding

    The size, density, and formation of the Orcus-Vanth system in the Kuiper belt

    Get PDF
    The Kuiper belt object Orcus and its satellite Vanth form an unusual system in the Kuiper belt. Orcus is amongst the largest objects known in the Kuiper belt, but the relative size of Vanth is much larger than that of the tiny satellites of the other large objects. From Hubble Space Telescope observations we find that Orcus and Vanth have different visible colors and that Vanth does not share the water ice absorption feature seen in the infrared spectrum of Orcus. We also find that Vanth has a nearly face-on circular orbit with a period of 9.5393 +-0.0001 days and semimajor axis of 8980+-20 km, implying a system mass of 6.32+- 0.01 X 10^20 kg or 3.8% the mass of dwarf planet Eris. From Spitzer Space Telescope observations we find that the thermal emission is consistent with a single body with diameter 940+-70 km and a geometric albedo of 0.28+-0.04. Assuming equal densities and albedos, this measurements implies sizes of Orcus and Vanth of 900 and 280 km, respectively, and a mass ratio of 33. Assuming a factor of 2 lower albedo for the non-icy Vanth, however, implies sizes of 820 and 640 km and a mass ratio of 2. The measured density depends on the assumed albedo ratio of the two objects but is approximately 1.5+-0.3 g cm^-3$, midway between typical densities measured for larger and for smaller objects. The orbit and mass ratio is consistent with formation from a giant impact and subsequent outward tidal evolution and even consistent with the system having now achieved a double synchronous state. The system can equally well be explained, however, by initial eccentric capture, Kozai cycling which increases the eccentricity and decreases the pericenter of the orbit of Vanth, and subsequent tidal evolution inward.Comment: Submitted to A

    Localization phenomena in Nonlinear Schrodinger equations with spatially inhomogeneous nonlinearities: Theory and applications to Bose-Einstein condensates

    Full text link
    We study the properties of the ground state of Nonlinear Schr\"odinger Equations with spatially inhomogeneous interactions and show that it experiences a strong localization on the spatial region where the interactions vanish. At the same time, tunneling to regions with positive values of the interactions is strongly supressed by the nonlinear interactions and as the number of particles is increased it saturates in the region of finite interaction values. The chemical potential has a cutoff value in these systems and thus takes values on a finite interval. The applicability of the phenomenon to Bose-Einstein condensates is discussed in detail

    Comprehensive analysis of karyotypic mosaicism between trophectoderm and inner cell mass

    Get PDF
    Aneuploidy has been well-documented in blastocyst embryos, but prior studies have been limited in scale and/or lack mechanistic data. We previously reported preclinical validation of microarray 24-chromosome preimplantation genetic screening in a 24-h protocol. The method diagnoses chromosome copy number, structural chromosome aberrations, parental source of aneuploidy and distinguishes certain meiotic from mitotic errors. In this study, our objective was to examine aneuploidy in human blastocysts and determine correspondence of karyotypes between trophectoderm (TE) and inner cell mass (ICM). We disaggregated 51 blastocysts from 17 couples into ICM and one or two TE fractions. The average maternal age was 31. Next, we ran 24-chromosome microarray molecular karyotyping on all of the samples, and then performed a retrospective analysis of the data. The average per-chromosome confidence was 99.95%. Approximately 80% of blastocysts were euploid. The majority of aneuploid embryos were simple aneuploid, i.e. one or two whole-chromosome imbalances. Structural chromosome aberrations, which are common in cleavage stage embryos, occurred in only three blastocysts (5.8%). All TE biopsies derived from the same embryos were concordant. Forty-nine of 51 (96.1%) ICM samples were concordant with TE biopsies derived from the same embryos. Discordance between TE and ICM occurred only in the two embryos with structural chromosome aberration. We conclude that TE karyotype is an excellent predictor of ICM karyotype. Discordance between TE and ICM occurred only in embryos with structural chromosome aberrations

    The dynamical evolution of dwarf planet (136108) Haumea's collisional family: General properties and implications for the trans-Neptunian belt

    Get PDF
    Recently, the first collisional family was identified in the trans-Neptunian belt. The family consists of Haumea and at least ten other ~100km-sized trans-Neptunian objects (TNOs) located in the region a = 42 - 44.5 AU. In this work, we model the long-term orbital evolution of an ensemble of fragments representing hypothetical post-collision distributions at the time of the family's birth. We consider three distinct scenarios, in which the kinetic energy of dispersed particles were varied such that their mean ejection velocities (veje) were of order 200 m/s, 300 m/s and 400 m/s, respectively. Each simulation considered resulted in collisional families that reproduced that currently observed. The results suggest that 60-75% of the fragments created in the collision will remain in the trans-Neptunian belt, even after 4 Gyr of dynamical evolution. The surviving particles were typically concentrated in wide regions of orbital element space centred on the initial impact location, with their orbits spread across a region spanning {\Delta}a ~ 6-12 AU, {\Delta}e ~ 0.1-0.15 and {\Delta}i ~ 7-10{\deg}. Most of the survivors populated the so-called Classical and Detached regions of the trans-Neptunian belt, whilst a minor fraction entered the Scattered Disk reservoir (<1%), or were captured in Neptunian mean motion resonances (<10%). In addition, except for those fragments located near strong resonances, the great majority displayed negligible long-term orbital variation. This implies that the orbital distribution of the intrinsic Haumean family can be used to constrain the orbital conditions and physical nature of the collision that created the family, billions of years ago. Indeed, our results suggest that the formation of the Haumean collisional family most likely occurred after the bulk of Neptune's migration was complete, or even some time after the migration had completely ceased.Comment: 38 pages, 13 figures, accepted for publication in MNRAS (The abstract was shortened. Original version can be found in the pdf file

    Trans-Neptunian binaries (2018)

    Full text link
    The discovery and characteristics of transneptunian binaries are reviewed. In the 20 years since their first discovery, a wealth of detail has emerged including the frequency of binaries in different populations, their relative sizes and separations, and colors. Taken globally, these properties give strong clues to the origin and evolution of the populations where these binaries are found. In the last ten years and increasing number of binary orbits have been determined which yields a new trove of information on their masses and densities as well as details of their orbits including inclination, eccentricity and the timing of mutual events. In 2018, the study of transneptunian binaries remains one of the most active areas of progress in understanding the Solar System beyond Neptune.Comment: 22 pages, 9 figures, 1 tabl

    Instability zones for satellites of asteroids. The example of the (87) Sylvia system

    Full text link
    We study the stability of the (87) Sylvia system and of the neighborhood of its two satellites. We use numerical integrations considering the non-sphericity of Sylvia, as well as the mutual perturbation of the satellites and the solar perturbation. Two numerical models have been used, which describe respectively the short and long-term evolution of the system. We show that the actual system is in a deeply stable zone, but surrounded by both fast and secular chaotic regions due to resonances. We then investigate how tidal and BYORP effects modify the location of the system over time with respect to the instability zones. Finally, we briefly generalize this study to other known triple systems and to satellites of asteroids in general, and discuss about their distance from mean-motion and evection resonances.Comment: 25 pages, 11 figures. Submitted to Icaru

    Mental health literacy and attitudes in a Swedish community sample – Investigating the role of personal experience of mental health care

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Mental ill health is a common condition in the general population, yet only about half of those with a mental disorder have treatment contact. Personal experience may affect attitudes, which in turn influence the help-seeking process. This study investigated differences in mental health literacy and attitudes among mentally healthy persons and in persons with symptoms of mental illness with and without treatment contact.</p> <p>Method</p> <p>A postal screening questionnaire was sent to a random sample of the general population aged 20–64 in the county of Skaraborg, Sweden in order to ascertain mental health status and history of treatment contact; 3538 responded (49%). Face-to-face interviews were carried out in random sub samples of mentally healthy persons (n = 128) and in mentally ill persons with (n = 125) and without (n = 105) mental health care contact. Mental health literacy and attitudes to treatment were assessed using questions based on a vignette depicting a person with depression. Past month mental disorder was diagnosed according to the Schedule for Clinical Assessment in Neuropsychiatry (SCAN).</p> <p>Results</p> <p>Two thirds failed to recognize depression in a vignette; recognition was equally poor in mentally healthy persons and in persons with symptoms of mental illness with and without treatment contact. In response to an open-ended question concerning appropriate interventions, one third suggested counselling and only one percent proposed antidepressant treatment. Again, proportions were similar in all groups. Persons with a history of mental health contact more often suggested that a GP would provide the best form of help. When presented with a list of possible interventions, those with a history of mental health contact were more positive to medical interventions such as antidepressants, hypnotics, and inpatient psychiatric treatment. When asked about the prognosis for the condition described in the vignette, persons with treatment contact were less likely to believe in full recovery without intervention; mentally ill without treatment contact were more optimistic.</p> <p>Conclusion</p> <p>Mental health literacy, specially concerning attitudes towards interventions is associated with personal history of mental health care.</p
    corecore