2,220 research outputs found
Pulse transducer with artifact signal attenuator
An artifact signal attenuator for a pulse rate sensor is described. The circuit for attenuating background noise signals is connected with a pulse rate transducer which has a light source and a detector for light reflected from blood vessels of a living body. The heart signal provided consists of a modulated dc signal voltage indicative of pulse rate. The artifact signal resulting from light reflected from the skin of the body comprises both a constant dc signal voltage and a modulated dc signal voltage. The amplitude of the artifact signal is greater and the frequency less than that of the heart signal. The signal attenuator circuit includes an operational amplifier for canceling the artifact signal from the output signal of the transducer and has the capability of meeting packaging requirements for wrist-watch-size packages
Cotreatment with a novel phosphoinositide analogue inhibitor and carmustine enhances chemotherapeutic efficacy by attenuating AKT activity in gliomas
Chandra observation of the fast X-ray transient IGR J17544-2619: evidence for a neutron star?
IGR J17544-2619 belongs to a distinct group of at least seven fast X-ray
transients that cannot readily be associated with nearby flare stars or
pre-main sequence stars and most probably are X-ray binaries with wind
accretion. Sofar, the nature of the accretor has been determined in only one
case (SAX J1819.3-2525/V4641 Sgr). We carried out a 20 ks Chandra ACIS-S
observation of IGR J17544-2619 which shows the source in quiescence going into
outburst. The Chandra position confirms the previous tentative identification
of the optical counterpart, a blue O9Ib supergiant at 3 to 4 kpc (Pellizza,
Chaty & Negueruela, in prep.). This is the first detection of a fast X-ray
transient in quiescence. The quiescent spectrum is very soft. The photon index
of 5.9+/-1.2 (90% confidence error margin) is much softer than 6 quiescent
black hole candidates that were observed with Chandra ACIS-S (Kong et al. 2002;
Tomsick et al. 2003). Assuming that a significant fraction of the quiescent
photons comes from the accretor and not the donor star, we infer that the
accretor probably is a neutron star. A fit to the quiescent spectrum of the
neutron star atmosphere model developed by Pavlov et al. (1992) and Zavlin et
al. (1996) implies an unabsorbed quiescent 0.5--10 keV luminosity of
(5.2+/-1.3) x 10^32 erg/s. We speculate on the nature of the brief outbursts.Comment: accepted for publication in Astronomy & Astrophysic
A New Family of Multistep Methods with Improved Phase Lag Characteristics for the Integration of Orbital Problems
In this work we introduce a new family of ten-step linear multistep methods
for the integration of orbital problems. The new methods are constructed by
adopting a new methodology which improves the phase lag characteristics by
vanishing both the phase lag function and its first derivatives at a specific
frequency. The efficiency of the new family of methods is proved via error
analysis and numerical applications.Comment: 21 pages, 3 figures, 1 tabl
Men, Muscles, and Body Image: Comparisons of Competitive Bodybuilders, Weight Trainers, and Athletically Active Controls
Objectives: To investigate body image and psychosocial adjustment among competitive bodybuilders, non-competitive weight trainers, and athletically active men. Methods: Participants were 40 men in each of the three groups who were assessed on body composition and multiple facets of body image evaluation, investment and anxiety, eating attitudes, and social self esteem. Results: Relative to the other two groups, competitive bodybuilders had greater body mass due to fat-free body mass. Although groups did not differ in their situational body image discomfort, competitive bodybuilders and weight trainers had a more positive global appearance evaluation and were more psychologically invested in their physical appearance. Compared with active controls, men in both weightlifting groups were more satisfied with their upper torso and muscle tone. Competitive bodybuilders reported more mid torso satisfaction than the other two groups. Competitive bodybuilders also wished to be significantly heavier than controls did and reported higher social self esteem but greater eating disturbance. Conclusions: The findings suggest that competitive bodybuilders as a group are not more muscle dysmorphic\u27\u27 than either non-competitive weight trainers or physically active men who do not train with weights
Brain Age from the Electroencephalogram of Sleep
The human electroencephalogram (EEG) of sleep undergoes profound changes with
age. These changes can be conceptualized as "brain age", which can be compared
to an age norm to reflect the deviation from normal aging process. Here, we
develop an interpretable machine learning model to predict brain age based on
two large sleep EEG datasets: the Massachusetts General Hospital sleep lab
dataset (MGH, N = 2,621) covering age 18 to 80; and the Sleep Hearth Health
Study (SHHS, N = 3,520) covering age 40 to 80. The model obtains a mean
absolute deviation of 8.1 years between brain age and chronological age in the
healthy participants in the MGH dataset. As validation, we analyze a subset of
SHHS containing longitudinal EEGs 5 years apart, which shows a 5.5 years
difference in brain age. Participants with neurological and psychiatric
diseases, as well as diabetes and hypertension medications show an older brain
age compared to chronological age. The findings raise the prospect of using
sleep EEG as a biomarker for healthy brain aging
Spatial Correlation Function of X-ray Selected AGN
We present a detailed description of the first direct measurement of the
spatial correlation function of X-ray selected AGN. This result is based on an
X-ray flux-limited sample of 219 AGN discovered in the contiguous 80.7 deg^2
region of the ROSAT North Ecliptic Pole (NEP) Survey. Clustering is detected at
the 4 sigma level at comoving scales in the interval r = 5-60 h^-1 Mpc. Fitting
the data with a power law of slope gamma=1.8, we find a correlation length of
r_0 = 7.4 (+1.8, -1.9) h^-1 Mpc (Omega_M=0.3, Omega_Lambda=0.7). The median
redshift of the AGN contributing to the signal is z_xi=0.22. This clustering
amplitude implies that X-ray selected AGN are spatially distributed in a manner
similar to that of optically selected AGN. Furthermore, the ROSAT NEP
determination establishes the local behavior of AGN clustering, a regime which
is poorly sampled in general. Combined with high-redshift measures from optical
studies, the ROSAT NEP results argue that the AGN correlation strength
essentially does not evolve with redshift, at least out to z~2.2. In the local
Universe, X-ray selected AGN appear to be unbiased relative to galaxies and the
inferred X-ray bias parameter is near unity, b_X~1. Hence X-ray selected AGN
closely trace the underlying mass distribution. The ROSAT NEP AGN catalog,
presented here, features complete optical identifications and spectroscopic
redshifts. The median redshift, X-ray flux, and X-ray luminosity are z=0.41,
f_X=1.1*10^-13 cgs, and L_X=9.2*10^43 h_70^-2 cgs (0.5-2.0 keV), respectively.
Unobscured, type 1 AGN are the dominant constituents (90%) of this soft X-ray
selected sample of AGN.Comment: 17 pages, 8 figures, accepted for publication in ApJ, a version with
high-resolution figures is available at
http://www.eso.org/~cmullis/papers/Mullis_et_al_2004b.ps.gz, a
machine-readable version of the ROSAT NEP AGN catalog is available at
http://www.eso.org/~cmullis/research/nep-catalog.htm
Comparison of the estimated incidence of acute leptospirosis in the Kilimanjaro Region of Tanzania between 2007-08 and 2012-14
Background:
The sole report of annual leptospirosis incidence in continental Africa of 75–102 cases per 100,000 population is from a study performed in August 2007 through September 2008 in the Kilimanjaro Region of Tanzania. To evaluate the stability of this estimate over time, we estimated the incidence of acute leptospirosis in Kilimanjaro Region, northern Tanzania for the time period 2012–2014.
Methodology and Principal Findings:
Leptospirosis cases were identified among febrile patients at two sentinel hospitals in the Kilimanjaro Region. Leptospirosis was diagnosed by serum microscopic agglutination testing using a panel of 20 Leptospira serovars belonging to 17 separate serogroups. Serum was taken at enrolment and patients were asked to return 4–6 weeks later to provide convalescent serum. Confirmed cases required a 4-fold rise in titre and probable cases required a single titre of ≥800. Findings from a healthcare utilisation survey were used to estimate multipliers to adjust for cases not seen at sentinel hospitals. We identified 19 (1.7%) confirmed or probable cases among 1,115 patients who presented with a febrile illness. Of cases, the predominant reactive serogroups were Australis 8 (42.1%), Sejroe 3 (15.8%), Grippotyphosa 2 (10.5%), Icterohaemorrhagiae 2 (10.5%), Pyrogenes 2 (10.5%), Djasiman 1 (5.3%), Tarassovi 1 (5.3%). We estimated that the annual incidence of leptospirosis was 11–18 cases per 100,000 population. This was a significantly lower incidence than 2007–08 (p<0.001).
Conclusions:
We estimated a much lower incidence of acute leptospirosis than previously, with a notable absence of cases due to the previously predominant serogroup Mini. Our findings indicate a dynamic epidemiology of leptospirosis in this area and highlight the value of multi-year surveillance to understand leptospirosis epidemiology
Evolution of the Cluster X-ray Luminosity Function
We report measurements of the cluster X-ray luminosity function out to z=0.8
based on the final sample of 201 galaxy systems from the 160 Square Degree
ROSAT Cluster Survey. There is little evidence for any measurable change in
cluster abundance out to z~0.6 at luminosities less than a few times 10^44
ergs/s (0.5-2.0 keV). However, between 0.6 < z < 0.8 and at luminosities above
10^44 ergs/s, the observed volume densities are significantly lower than those
of the present-day population. We quantify this cluster deficit using
integrated number counts and a maximum-likelihood analysis of the observed
luminosity-redshift distribution fit with a model luminosity function. The
negative evolution signal is >3 sigma regardless of the adopted local
luminosity function or cosmological framework. Our results and those from
several other surveys independently confirm the presence of evolution. Whereas
the bulk of the cluster population does not evolve, the most luminous and
presumably most massive structures evolve appreciably between z=0.8 and the
present. Interpreted in the context of hierarchical structure formation, we are
probing sufficiently large mass aggregations at sufficiently early times in
cosmological history where the Universe has yet to assemble these clusters to
present-day volume densities.Comment: 15 pages, 10 figures, accepted for publication in Ap
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