373 research outputs found
Biochemical correlates of cardiac hypertrophy. I. Experimental model; changes in heart weight, RNA content, and nuclear RNA polymerase activity
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
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
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
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
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)
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
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
<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
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