3,287 research outputs found
A Physiologic Evaluation of the Sports Massage
This study determines the physiological responses of 10 healthy college-age subjects during submaximal exercise on the treadmill with and without a prior 30-minute sports massage. The Beckman Metabolic Measurement Cart was used to determine the subjects\u27 steady-state responses. Cardiac output was determined by the indirect CO2 Fick method; mixed venous PCO2 was calculated using the equilibrium CO 2 rebreathing method. No significant differences in central (HR, SV, Q) or peripheral (a-v~O2 diff) responses were found between the two submaximal exercise tests. Also, there were no significant differences in lactic acid (LA) and blood pressure responses. The results indicate that massage immediately prior to submaximal exercise at 80% intensity had no effect on the subjects\u27 cardiovascular systems
X-Ray Wind Tomography of the highly absorbed HMXB IGR J17252-3616
Our goal is to understand the specificities of highly absorbed sgHMXB and in
particular of the companion stellar wind, thought to be responsible for the
strong absorption. We have monitored IGR J17252-3616, a highly absorbed system
featuring eclipses, with XMM-Newton to study the vari- ability of the column
density and of the Fe K{\alpha} emission line along the orbit and during the
eclipses. We also built a 3D model of the structure of the stellar wind to
reproduce the observed variability. We first derived a refined orbital solution
built from INTEGRAL, RXTE and XMM data. The XMM monitoring campaign revealed
significant variation of intrinsic absorbing column density along the orbit and
of the Fe K{\alpha} line equivalent width around the eclipses. The origin of
the soft X-ray absorption is modeled with an dense and extended hydrodynamical
tail, trailing the neutron star. This structure extends along most of the
orbit, indicating that the stellar wind is strongly disrupted by the neutron
star. The variability of the absorbing column density suggests that the
terminal velocity of the wind is smaller (~400 km/s) than observed in classical
systems. This can also explain the much stronger density perturbation inferred
from the observations. Most of the Fe K{\alpha} emission is generated in the
most inner region of the hydrodynamical tail. This region, that extends over a
few accretion radii, is ionized and does not contribute to the soft X-ray
absorption. We have built a qualitative model of the stellar wind of IGR
J17252-3616 that can represent the observations and suggest that highly
absorbed systems have a lower wind velocity than classical sgHMXB. This
proposal could be tested with de- tailed numerical simulations and
high-resolution infrared/optical observations. If confirmed, it may turn out
that half of the persistent sgHMXB have low stellar wind speeds.Comment: 9 pages, 8 figure
Stringent neutron-star limits on large extra dimensions
Supernovae (SNe) are copious sources for Kaluza-Klein gravitons which are
generic for theories with large extra dimensions. These massive particles are
produced with average velocities ~0.5 c so that many of them are
gravitationally retained by the SN core. Every neutron star thus has a halo of
KK gravitons which decay into nu bar-nu, e^+e^- and gamma gamma on time scales
\~10^9 years. The EGRET gamma-flux limits (E_gamma ~ 100 MeV) for nearby
neutron stars constrain the fundamental scale for n=2 extra dimensions to M
>500 TeV, and M>30 TeV for n=3. The upcoming GLAST satellite is a factor ~30
more sensitive and thus may detect KK decays, for example at the nearby neutron
star RX J185635--3754. The requirement that neutron stars are not excessively
heated by KK decays implies M>1700 TeV for n=2, and M>60 TeV for n=3.Comment: Minor changes, matches version to appear in PR
Creatine Kinase, Creatine Kinase‑MM, and the Isoforms of Creatine Kinase‑MM Following a Competitive Swimming Workout
Serum levels of total creatine kinase (CK), CK-MM and the isoform of CD-MM were measured in 14 male competitive collegiate swimmers. The purpose of this study was to observe changes in CK and the isoforms of CK-MM following a competitive swim training session. Venous blood samples were taken before and immediately following a 5550 yard training session. The main series in the workout consisted of a 27 minute, minimal rest interval set designed to obtain a moderately heavy physical effort. Total CK, composed predominantly of CK-MM, increased significantly (
Development of a Suicide Inhibition-Based Protein Labeling Strategy for Nicotinamide N-Methyltransferase
Nicotinamide N-methyltransferase (NNMT) catalyzes the S-adenosyl-l-methionine-dependent methylation of nicotinamide to form N-methylnicotinamide. This enzyme detoxifies xenobiotics and regulates NAD+ biosynthesis. Additionally, NNMT is overexpressed in various cancers. Herein, we describe the first NNMT-targeted suicide substrates. These compounds, which include 4-chloropyridine and 4-chloronicotinamide, exploit the broad substrate scope of NNMT; methylation of the pyridine nitrogen enhances the electrophilicity of the C4 position, thereby promoting an aromatic nucleophilic substitution by C159, a noncatalytic cysteine. On the basis of this activity, we developed a suicide inhibition-based protein labeling strategy using an alkyne-substituted 4-chloropyridine that selectively labels NNMT in vitro and in cells. In total, this study describes the first NNMT-directed activity-based probes
The Orbit of the Eclipsing X-ray Pulsar EXO 1722-363
With recent and archival Rossi X-Ray Timing Explorer (RXTE) X-ray
measurements of the heavily obscured X-ray pulsar EXO 1722-363 (IGR
J17252-3616), we carried out a pulse timing analysis to determine the orbital
solution for the first time. The binary system is characterized by a_x sin(i) =
101 +/- 3 lt-s and P_orb = 9.7403 +/- 0.0004 days (90% confidence), with the
precision of the orbital period being obtained by connecting datasets separated
by more than 7 years (272 orbital cycles). The orbit is consistent with
circular, and e < 0.19 at the 90% confidence level. The mass function is 11.7
+/- 1.2 M_sun and confirms that this source is a High Mass X-ray Binary (HMXB)
system. The orbital period, along with the previously known ~414 s pulse
period, places this system in the part of the Corbet diagram populated by
supergiant wind accretors. Using previous eclipse time measurements by Corbet
et al. and our orbital solution, combined with the assumption that the primary
underfills its Roche lobe, we find i > 61 degrees at the 99% confidence level,
the radius of the primary is between 21 R_sun and 37 R_sun, and its mass is
less than about 22 M_sun. The acceptable range of radius and mass shows that
the primary is probably a supergiant of spectral type B0I-B5I. Photometric
measurements of its likely counterpart are consistent with the spectral type
and luminosity if the distance to the system is between 5.3 kpc and 8.7 kpc.
Spectral analysis of the pulsar as a function of orbital phase reveals an
evolution of the hydrogen column density suggestive of dense filaments of gas
in the downstream wake of the pulsar, with higher levels of absorption seen at
orbital phases 0.5-1.0, as well as a variable Fe K_alpha line.Comment: Submitted to ApJ, 11 pages, 11 figure
Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. I. The nature of the companion star
Context: The INTEGRAL hard X-ray observatory has revealed an emerging
population of highly obscured X-ray binary systems through multi-wavelength
observations. Previous studies have shown that many of these sources are
high-mass X-ray binaries hosting neutron stars orbiting around luminous and
evolved companion stars. Aims: To better understand this newly-discovered
population, we have selected a sample of sources for which an accurate
localisation is available to identify the stellar counterpart and reveal the
nature of the companion star and of the binary system. Methods: We performed an
intensive study of a sample of thirteen INTEGRAL sources, through
multi-wavelength optical to NIR photometric and spectroscopic observations,
using EMMI and SofI instruments at the ESO NTT telescope. We performed accurate
astrometry and identified candidate counterparts for which we give the optical
and NIR magnitudes. We detected many spectral lines allowing us to determine
the spectral type of the companion star. We fitted with stellar black bodies
the mid-infrared to optical spectral energy distributions of these sources.
From the spectral analysis and SED fitting we identified the nature of the
companion stars and of the binary systems. (abridged).Comment: A&A in press; The official date of acceptance is 15/12/2007; 25
pages, 6 figures, 8 tables. New version with language editing required by
edito
Exceptional flaring activity of the anomalous X-ray pulsar 1E 1547.0-5408
(Abridged) We studied an exceptional period of activity of the anomalous
X-ray pulsar 1E 1547.0-5408 in January 2009, during which about 200 bursts were
detected by INTEGRAL. The major activity episode happened when the source was
outside the field of view of all the INTEGRAL instruments. But we were still
able to study the properties of 84 bursts detected simultaneously by the
anti-coincidence shield of the spectrometer SPI and by the detector of the
imager ISGRI. We find that the luminosity of the 22 January 2009 bursts of 1E
1547.0-5408 was > 1e42 erg/s. This luminosity is comparable to that of the
bursts of soft gamma repeaters (SGR) and is at least two orders of magnitude
larger than the luminosity of the previously reported bursts from AXPs.
Similarly to the SGR bursts, the brightest bursts of 1E 1547.0-5408 consist of
a short spike of ~100 ms duration with a hard spectrum, followed by a softer
extended tail of 1-10 s duration, which occasionally exhibits pulsations with
the source spin period of ~2 s. The observation of AXP bursts with luminosities
comparable to the one of SGR bursts strengthens the conjecture that AXPs and
SGRs are different representatives of one and the same source type.Comment: 9 pages, 10 figures, accepted to Astronomy & Astrophysic
Detection of fast radio transients with multiple stations: a case study using the Very Long Baseline Array
Recent investigations reveal an important new class of transient radio
phenomena that occur on sub-millisecond timescales. Often transient surveys'
data volumes are too large to archive exhaustively. Instead, an on-line
automatic system must excise impulsive interference and detect candidate events
in real-time. This work presents a case study using data from multiple
geographically distributed stations to perform simultaneous interference
excision and transient detection. We present several algorithms that
incorporate dedispersed data from multiple sites, and report experiments with a
commensal real-time transient detection system on the Very Long Baseline Array
(VLBA). We test the system using observations of pulsar B0329+54. The
multiple-station algorithms enhanced sensitivity for detection of individual
pulses. These strategies could improve detection performance for a future
generation of geographically distributed arrays such as the Australian Square
Kilometre Array Pathfinder and the Square Kilometre Array.Comment: 12 pages, 14 figures. Accepted for Ap
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