3,241 research outputs found
Cardiovascular Effects of Long Term Androgenic Anabolic Steroid Use
Background: Anabolic steroids have been a consistent area of debate when it comes to athletes. Anabolic steroids are very common in certain sports like powerlifting and bodybuilding. Negative health effects have been found to be associated with the long term use of anabolic steroids. The objective of this review is to determine if there are negative cardiovascular effects associated with chronic androgenic anabolic steroid use when compared to non-steroid users.
Methods: A literature review of past research articles was performed. Pertinent information was obtained from the sources and compiled as evidence for the topic of this paper.
Results: Using primarily bodybuilder populations, the findings obtained from the articles supported decreased left ventricular function, increase in blood pressure, atherosclerosis of blood vessels, and an increase in LDL with a decrease in HDL.
Conclusion: Anabolic steroids can be contributed to decreased left ventricular function, increased blood pressure, atherosclerosis, and increase LDL and decrease HDL leading to an overall decrease in cardiovascular function. Improving education on the cardiovascular impact anabolic steroids can have can ultimately decrease the risk of individuals abusing these drugs and having a decrease in overall health
"Distance mapping" and the 3-D structure of BB +30 3639
BD +30 3639 is a member of a group of uncommon planetary nebula with
Wolf-Rayet central star and higher expansion velocities in [O III] than in [N
II] lines. Images and high-resolution spectra from the literature are used in
order to construct a 3-D model of the nebula using the morpho-kinematic code
SHAPE. We find that two homologous expansion laws are needed for the [N II] and
[O III] shell. We conclude that the internal velocity field of BD +30 3639
decreases with the distance from the central star at least between the [O III]
and [N II] shells. A cylindrical velocity component is used to replicate the
high-speed bipolar collimated outflows. We also present a new kinematic
analysis technique called "distance mapping". It uses the observed proper
motion vectors and the 3-D velocity field to generate maps that can be used as
a constraint to the morpho-kinematic modeling with SHAPE as well as improve the
accuracy for distance determination. It is applied to BD+30 3639 using 178
internal proper motion vectors from Li et al. (2002) and our 3-D velocity field
to determine a distance of 1.52 \pm 0.21 kpc. Finally, we find evidence for an
interaction between the eastern part of nebula and the ambient H2 molecular
gas.Comment: 11 pages, 12 figures, 1 table, Accepted to MNRA
A pseudo-planar, periodic-box formalism for modelling the outer evolution of structure in spherically expanding stellar winds
We present an efficient technique to study the 1D evolution of
instability-generated structure in winds of hot stars out to very large
distances (more than 1000 stellar radii). This technique makes use of our
previous finding that external forces play little role in the outer evolution
of structure. Rather than evolving the entire wind, as is traditionally done,
the technique focuses on a representative portion of the structure and follows
it as it moves out with the flow. This requires the problem to be formulated in
a moving reference frame. The lack of Galilean invariance of the spherical
equations of hydrodynamics is circumvented by recasting them in a pseudo-planar
form. By applying the technique to a number of problems we show that it is fast
and accurate, and has considerable conceptual advantages. It is particularly
useful to test the dependence of solutions on the Galilean frame in which they
were obtained. As an illustration, we show that, in a one-dimensional
approximation, the wind can remain structured out to distances of more than
1300 stellar radii from the central star.Comment: submitted to Astronomy and Astrophysics, 12 pages, 13 figure
The bright optical afterglow of the long GRB 001007
We present optical follow up observations of the long GRB 001007 between 6.14
hours and ~468 days after the event. An unusually bright optical afterglow (OA)
was seen to decline following a steep power law decay with index alpha = -2.03
+/- 0.11, possibly indicating a break in the light curve at t - to < 3.5 days,
as found in other bursts. Upper limits imposed by the LOTIS alerting system
6.14 hours after the gamma ray event provide tentative (1.2 sigma) evidence for
a break in the optical light curve. The spectral index beta of the OA yields
-1.24 +/- 0.57. These values may be explained both by several fireball jet
models and by the cannonball model. Fireball spherical expansion models are not
favoured. Late epoch deep imaging revealed the presence of a complex host
galaxy system, composed of at least two objects located 1.2" (1.7 sigma) and
1.9" (2.7 sigma) from the afterglow position.Comment: 7 pages, 5 figures, published in A&
Revealing evolved massive stars with Spitzer
Massive evolved stars loss a large fraction of their mass via copious stellar
wind or instant outbursts and during certain evolutionary phases they can be
identified via the presence of their circumstellar nebulae. In this paper, we
present the results of search for compact nebulae (reminiscent of circumstellar
nebulae around evolved massive stars) using archival 24 m data obtained
with the Multiband Imaging Photometer for Spitzer. We discovered 115 nebulae,
most of which bear a striking resemblance to the circumstellar nebulae
associated with Luminous Blue Variables (LBVs) and late WN-type (WNL)
Wolf-Rayet (WR) stars in the Milky Way and the Large Magellanic Cloud (LMC). We
interpret this similarity as an indication that the central stars of detected
nebulae are either LBVs or related evolved massive stars. Our interpretation is
supported by follow-up spectroscopy of two dozens of these central stars, most
of which turns out to be either candidate LBVs (cLBVs), blue supergiants or WNL
stars. We expect that the forthcoming spectroscopy of the remaining objects
from our list, accompanied by the spectrophotometric monitoring of the already
discovered cLBVs, will further increase the known population of Galactic LBVs,
which in turn would have profound consequences for better understanding the LBV
phenomenon and its role in the transition between hydrogen burning O stars and
helium burning WR stars. We also report the detection of an arc-like structure
attached to the cLBV HD326823 and an arc associated with the LBV R99 (HD269445)
in the LMC.Comment: 9 pages, 10 figures, accepted to MNRA
A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)
We present a measurement of time-dependent CP-violating asymmetries in
neutral B meson decays collected with the BABAR detector at the PEP-II
asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data
sample consists of 29.7 recorded at the
resonance and 3.9 off-resonance. One of the neutral B mesons,
which are produced in pairs at the , is fully reconstructed in
the CP decay modes , , , () and , or in flavor-eigenstate
modes involving and (). The flavor of the other neutral B meson is tagged at the time of
its decay, mainly with the charge of identified leptons and kaons. The proper
time elapsed between the decays is determined by measuring the distance between
the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample
finds . The value of the asymmetry amplitude is determined from
a simultaneous maximum-likelihood fit to the time-difference distribution of
the flavor-eigenstate sample and about 642 tagged decays in the
CP-eigenstate modes. We find , demonstrating that CP violation exists in the neutral B meson
system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review
ANCHOR: a web server and database for analysis of protein–protein interaction binding pockets for drug discovery
ANCHOR is a web-based tool whose aim is to facilitate the analysis of protein–protein interfaces with regard to its suitability for small molecule drug design. To this end, ANCHOR exploits the so-called anchor residues, i.e. amino acid side-chains deeply buried at protein–protein interfaces, to indicate possible druggable pockets to be targeted by small molecules. For a given protein–protein complex submitted by the user, ANCHOR calculates the change in solvent accessible surface area (ΔSASA) upon binding for each side-chain, along with an estimate of its contribution to the binding free energy. A Jmol-based tool allows the user to interactively visualize selected anchor residues in their pockets as well as the stereochemical properties of the surrounding region such as hydrogen bonding. ANCHOR includes a Protein Data Bank (PDB) wide database of pre-computed anchor residues from more than 30 000 PDB entries with at least two protein chains. The user can query according to amino acids, buried area (SASA), energy or keywords related to indication areas, e.g. oncogene or diabetes. This database provides a resource to rapidly assess protein–protein interactions for the suitability of small molecules or fragments with bioisostere anchor analogues as possible compounds for pharmaceutical intervention. ANCHOR web server and database are freely available at http://structure.pitt.edu/anchor
Measurement of ISR-FSR interference in the processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma
Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi-
gamma is measured using 232 fb-1 of data collected with the BABAR detector at
center-of-mass energies near 10.58 GeV. An observable is introduced and shown
to be very robust against detector asymmetries while keeping a large
sensitivity to the physical charge asymmetry that results from the interference
between initial and final state radiation. The asymmetry is determined as
afunction of the invariant mass of the final-state tracks from production
threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e-
--> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A
clear interference pattern is observed in e+ e- --> pi+ pi- gamma, particularly
in the vicinity of the f_2(1270) resonance. The inferred rate of lowest order
FSR production is consistent with the QED expectation for e+ e- --> mu+ mu-
gamma, and is negligibly small for e+ e- --> pi+ pi- gamma.Comment: 32 pages,29 figures, to be submitted to Phys. Rev.
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