5,170 research outputs found
SIMS chemical analysis of extended impact features from the trailing edge portion of experiment AO187-2
One hundred capture cells from the trailing edge, which had lost their cover foils during flight, were optically scanned for extended impact features caused by high velocity projectiles impinging on the cells while the foils were still intact. Of the 53 candidates, 24 impacts were analyzed by secondary ion mass spectroscopy for the chemical composition of the deposits. Projectile material was found in all impacts, and at least 75 percent of them appear to be caused by interplanetary dust particles. Elemental ratios are fractionated, with refractory elements enriched in the impacts relative to interplanetary dust particles collected in the stratosphere. Although this could be due to systematic differences in the compositions, a more likely explanation is volatility fractionation during the impact process
Cortisol is related to acute leukocytosis in maximal but not in hypertrophic dynamic resistance exercise
Introduction. Exercise induces immune changes that are multifactorial and include neuroendocrine factors. Acute resistance exercise is followed by marked increases in adrenaline, cortisol, growth hormone, and other factors that have immunomodulatory effects. The purpose of the present study was to investigate the relationship between leukocytosis and hormone responses to two different resistance exercises, low volume high load (gains in maximal strength, MAX) and high volume medium load (gains in muscle mass, HYP).
Methods. Using a cross-over design twelve healthy men participated in bilateral leg press exercise consisting of 5 sets of 10 RM and 15 sets of 1 RM. The inter-set rest period was 3 minutes for MAX and 2 minutes for HYP. Venous blood samples were taken at baseline, immediately after (P0) and 15 (P15) and 30 (P30) minutes after the exercise. Basic blood count was analyzed using Sysmex KX-21N (TOA Medical Electronics Co., Ltd., Kobe, Japan). Serum cortisol (COR), testosterone (TES), and growth hormone (GH) concentrations were analyzed by an immunometric chemiluminence method (Immunlite R 1000, DPC, Los Angeles, USA)
Results. Both exercises induced significant acute leukocytosis (p\u3c0.001). Leukocytosis was significantly higher after HYP (p\u3c0.01). COR and TES increased significantly after HYP (p\u3c0.01) but not in MAX. GH increased significantly (p\u3c0.05) in both exercises and stayed elevated at P30 in HYP. There was a significant negative correlation between acute leukocytosis and cortisol at P0 in MAX (R=-0.622, p=0.031) but not in HYP r=0.287 (p=0.366). Significant correlations between TES, GH and leukocytes were not observed.
Conclusions. Clearly, manipulation of the rest period and load in resistance exercise alters endocrinal as well as immunological responses. Hypertrophic resistance exercise triggered significantly stronger immunological as well as endocrinal responses. In line with the previous studies (e.g. Kraemer et al. 1996) cortisol did not correlate with leukocytes nor with leukocyte subgroups in HYP. It might be that cortisol acts as an anti-inflammatory agent in MAX, however in HYP leukocytosis appears to be related to additional physiological mechanisms e.g. muscle damage and metabolic demands, which might explain why we did not observe the same in HYP. When considering recovery from resistance exercise the immune system should be monitored in addition to hormones
The Arecibo Methanol Maser Galactic Plane Survey - III: Distances and Luminosities
We derive kinematic distances to the 86 6.7 GHz methanol masers discovered in
the Arecibo Methanol Maser Galactic Plane Survey. The systemic velocities of
the sources were derived from 13CO (J=2-1), CS (J=5-4), and NH3 observations
made with the ARO Submillimeter Telescope, the APEX telescope, and the
Effelsberg 100 m telescope, respectively. Kinematic distance ambiguities were
resolved using HI self-absorption with HI data from the VLA Galactic Plane
Survey. We observe roughly three times as many sources at the far distance
compared to the near distance. The vertical distribution of the sources has a
scale height of ~ 30 pc, and is much lower than that of the Galactic thin disk.
We use the distances derived in this work to determine the luminosity function
of 6.7 GHz maser emission. The luminosity function has a peak at approximately
10^{-6} L_sun. Assuming that this luminosity function applies, the methanol
maser population in the Large Magellanic Cloud and M33 is at least 4 and 14
times smaller, respectively, than in our Galaxy.Comment: Accepted by Ap
Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity
We investigate the nature of the long-period radial velocity variations in
Alpha Tau first reported over 20 years ago. We analyzed precise stellar radial
velocity measurements for Alpha Tau spanning over 30 years. An examination of
the Halpha and Ca II 8662 spectral lines, and Hipparcos photometry was also
done to help discern the nature of the long-period radial velocity variations.
Our radial velocity data show that the long-period, low amplitude radial
velocity variations are long-lived and coherent. Furthermore, Halpha equivalent
width measurements and Hipparcos photometry show no significant variations with
this period. Another investigation of this star established that there was no
variability in the spectral line shapes with the radial velocity period. An
orbital solution results in a period of P = 628.96 +/- 0.90 d, eccentricity, e
= 0.10 +/- 0.05, and a radial velocity amplitude, K = 142.1 +/- 7.2 m/s.
Evolutionary tracks yield a stellar mass of 1.13 +/- 0.11 M_sun, which
corresponds to a minimum companion mass of 6.47 +/- 0.53 M_Jup with an orbital
semi-major axis of a = 1.46 +/- 0.27 AU. After removing the orbital motion of
the companion, an additional period of ~ 520 d is found in the radial velocity
data, but only in some time spans. A similar period is found in the variations
in the equivalent width of Halpha and Ca II. Variations at one-third of this
period are also found in the spectral line bisector measurements. The 520 d
period is interpreted as the rotation modulation by stellar surface structure.
Its presence, however, may not be long-lived, and it only appears in epochs of
the radial velocity data separated by 10 years. This might be due to an
activity cycle. The data presented here provide further evidence of a planetary
companion to Alpha Tau, as well as activity-related radial velocity variations.Comment: 18 pages, 14 figures. Accepted for publication in Astronomy and
Astrophysic
Modelling Neglected Tropical Diseases diagnostics: the sensitivity of skin snips for Onchocerca volvulus in near elimination and surveillance settings.
BACKGROUND: The African Programme for Onchocerciasis Control has proposed provisional thresholds for the prevalence of microfilariae in humans and of L3 larvae in blackflies, below which mass drug administration (MDA) with ivermectin can be stopped and surveillance started. Skin snips are currently the gold standard test for detecting patent Onchocerca volvulus infection, and the World Health Organization recommends their use to monitor progress of treatment programmes (but not to verify elimination). However, if they are used (in transition and in parallel to Ov-16 serology), sampling protocols should be designed to demonstrate that programmatic goals have been reached. The sensitivity of skin snips is key to the design of such protocols. METHODS: We develop a mathematical model for the number of microfilariae in a skin snip and parameterise it using data from Guatemala, Venezuela, Ghana and Cameroon collected before the start of ivermectin treatment programmes. We use the model to estimate sensitivity as a function of time since last treatment, number of snips taken, microfilarial aggregation and female worm fertility after exposure to 10 annual rounds of ivermectin treatment. RESULTS: The sensitivity of the skin snip method increases with time after treatment, with most of the increase occurring between 0 and 5Â years. One year after the last treatment, the sensitivity of two skin snips taken from an individual infected with a single fertile female worm is 31Â % if there is no permanent effect of multiple ivermectin treatments on fertility; 18Â % if there is a 7Â % reduction per treatment, and 0.6Â % if there is a 35Â % reduction. At 5Â years, the corresponding sensitivities are 76Â %, 62Â % and 4.7Â %. The sensitivity improves significantly if 4 skin snips are taken: in the absence of a permanent effect of ivermectin, the sensitivity of 4 skin snips is 53Â % 1Â year and 94Â % 5Â years after the last treatment. CONCLUSIONS: Our model supports the timelines proposed by APOC for post-MDA follow-up and surveillance surveys every 3-5 years. Two skin snips from the iliac region have reasonable sensitivity to detect residual infection, but the sensitivity can be significantly improved by taking 4 snips. The costs and benefits of using four versus two snips should be evaluated
Response to the Letter to the Editor by Eberhard et al.
In a Letter to the Editor, Eberhard et al. question the validity of our model of skin snip sensitivity and argue against the use of skin snips to evaluate onchocerciasis elimination by mass drug administration. Here we discuss their arguments and compare model predictions with observed data to assess the validity of our model
Purity of Gaussian states: measurement schemes and time-evolution in noisy channels
We present a systematic study of the purity for Gaussian states of
single-mode continuous variable systems. We prove the connection of purity to
observable quantities for these states, and show that the joint measurement of
two conjugate quadratures is necessary and sufficient to determine the purity
at any time. The statistical reliability and the range of applicability of the
proposed measurement scheme is tested by means of Monte Carlo simulated
experiments. We then consider the dynamics of purity in noisy channels. We
derive an evolution equation for the purity of general Gaussian states both in
thermal and squeezed thermal baths. We show that purity is maximized at any
given time for an initial coherent state evolving in a thermal bath, or for an
initial squeezed state evolving in a squeezed thermal bath whose asymptotic
squeezing is orthogonal to that of the input state.Comment: 9 Pages, 6 Figures; minor errors correcte
Stellar Kinematics of the Andromeda II Dwarf Spheroidal Galaxy
We present kinematical profiles and metallicity for the M31 dwarf spheroidal
(dSph) satellite galaxy Andromeda II (And II) based on Keck DEIMOS spectroscopy
of 531 red giant branch stars. Our kinematical sample is among the largest for
any M31 satellite and extends out to two effective radii (r_eff = 5.3' = 1.1
kpc). We find a mean systemic velocity of -192.4+-0.5 km/s and an average
velocity dispersion of sigma_v = 7.8+-1.1 km/s. While the rotation velocity
along the major axis of And II is nearly zero (<1 km/s), the rotation along the
minor axis is significant with a maximum rotational velocity of v_max=8.6+-1.8
km/s. We find a kinematical major axis, with a maximum rotational velocity of
v_max=10.9+-2.4 km/s, misaligned by 67 degrees to the isophotal major axis. And
II is thus the first dwarf galaxy with evidence for nearly prolate rotation
with a v_max/sigma_v = 1.1, although given its ellipticity of epsilon = 0.10,
this object may be triaxial. We measured metallicities for a subsample of our
data, finding a mean metallicity of [Fe/H] = -1.39+- 0.03 dex and an internal
metallicity dispersion of 0.72+-0.03 dex. We find a radial metallicity gradient
with metal-rich stars more centrally concentrated, but do not observe a
significant difference in the dynamics of two metallicity populations. And II
is the only known dwarf galaxy to show minor axis rotation making it a unique
system whose existence offers important clues on the processes responsible for
the formation of dSphs.Comment: 14 pages, 10 figures, 4 tables, accepted for publication in Ap
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