916 research outputs found
Analytical determination of orbital elements using Fourier analysis. I. The radial velocity case
We describe an analytical method for computing the orbital parameters of a
planet from the periodogram of a radial velocity signal. The method is very
efficient and provides a good approximation of the orbital parameters. The
accuracy is mainly limited by the accuracy of the computation of the Fourier
decomposition of the signal which is sensitive to sampling and noise. Our
method is complementary with more accurate (and more expensive in computer
time) numerical algorithms (e.g. Levenberg-Marquardt, Markov chain Monte Carlo,
genetic algorithms). Indeed, the analytical approximation can be used as an
initial condition to accelerate the convergence of these numerical methods. Our
method can be applied iteratively to search for multiple planets in the same
system.Comment: accepted to A&
Chemical and Toxicological Characterization of the Upper York River, Virginia The Mattaponi and Pamunkey Rivers
This study describes the most extensive effort to characterize the chemistry, toxicology and community of the sediments of the Mattaponi and Pamunkey Rivers. This was accomplished using a study design modified to expand the number of stations occupied by reducing the cost of analyses by compositing replicate samples collected from each study site rather than performing toxicity tests on these samples individually. In previous studies, the variability in field replicate samples was equivalent to the variability in laboratory replicates. This design has long been used to analyze samples for various chemical contaminants as a cost savings endeavor. More ...
Chemical and toxicological characterization of the lower Mobjack Bay, York River, Virginia segment of the Chesapeake Bay
The Chesapeake Bay segment called Lower Mobjack Bay Lower York River Virginia was found to have insufficient data to characterize in 1999. Therefore this area was selected for a chemical, toxicological, benthic community characterization study of the sediments in 2002. The segment was divided into 3 strata: the lower York River, the Poquoson River, and Back River, each with 4 randomly selected stations. Samples were collected in October 2002 for evaluation of conditions.
There were few significant chemical exceedances of the ER-L or ER-M in the three strata and no toxicologically effects from exposure to sediment samples from any stratum. In contrast, the Poquoson and Back River strata showed consistent community degradation ranging from degraded to seriously degraded. The lack of chemical and toxicological impacts and the intensive residential land use makes it reasonable to conclude that the likely explanation for the degraded benthic community is eutrophication. There is not, however, confirmatory data for this interpretation
Recurrent Bacteremia, a Complication of Cyanoacrylate Injection for Variceal Bleeding: Report of Two Cases and Review of the Literature
We report the first description of recurrent bacteremia in two patients after cyanoacrylate injection for gastric varices bleeding treated with antibiotics alone. Adapted and prolonged antibiotic treatment allowed a complete resolution of the infection with no relapse after more than 6 months. According to recent data, prophylactic antibiotics should be further investigated for patients with bleeding varices undergoing cyanoacrylate injection
Essential requirement for sphingosine kinase activity in eNOS-dependent NO release and vasorelaxation
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that acts both as an extracellular ligand for endothelial differentiation gene receptor family and as an intracellular second messenger. Cellular levels of S1P are low and tightly regulated by sphingosine kinase (SPK). Recent studies have suggested that eNOS pathway may function as a downstream target for the biological effects of receptor-mediated S1P. Here we have studied the possible interplay between intracellular SIP generation and the eNOS activation pathway. S1P causes an endothelium-dependent vasorelaxation in rat aorta that is PTX sensitive, inhibited by L-NAME that involves eNOS phosphorylation, and mainly dependent on hsp90. When rat aorta rings were incubated with the SPK inhibitor DL-threo-dihydrosphingosine (DTD), there was a concentration-dependent reduction of Ach-induced vasorelaxation, implying a consistent contribution of sphingolipid pathway through intracellular sphingosine release and phosphorylation. Co-immunoprecipitation experiments consistently showed increased association of hsp90 with eNOS after exposure of cells to S1P as well to BK or calcium ionophore A-23187. Interestingly, as opposite to A-23187, BK and S1P effect were significantly inhibited by pretreatment with the SPK inhibitor DTD. In conclusion, our data demonstrate that an interplay exists among eNOS, hsp90, and intracellularly generated S1P where eNOS coupling to hsp90 is a major determinant for NO release as confirmed by our functional and molecular studies
A 12-month follow-up of a mobile-based (mHealth) obesity prevention intervention in pre-school children: the MINISTOP randomized controlled trial
Background: To date, few mobile health (mHealth) interventions aimed at changing lifestyle behaviors have
measured long term effectiveness. At the 6-month follow-up the MINISTOP trial found a statistically significant
intervention effect for a composite score comprised of fat mass index (FMI) as well as dietary and physical activity
variables; however, no intervention effect was observed for FMI. Therefore, the aim of this study was to investigate
if the MINISTOP intervention 12-months after baseline measurements: (i) improved FMI and (ii) had a maintained
effect on a composite score comprised of FMI and dietary and physical activity variables.
Methods: A two-arm parallel randomized controlled trial was conducted in 315 healthy 4.5 year old children
between January 2014 and October 2015. Parents’ of the participating children either received the MINISTOP
intervention or a basic pamphlet on dietary and physical activity behaviors (control group). After 6 months,
participants did not have access to the intervention content and were measured again 6 months later (i.e. the
12-month follow-up). The Wilcoxon rank-sum test was then used to examine differences between the groups.
Results: At the 12-month follow-up, no statistically significant difference was observed between the intervention
and control groups for FMI (p = 0.57) and no maintained effect for the change in composite score was observed
(mean ± standard deviation for the intervention and control group: + 0.53 ± 1.49 units and + 0.35 ± 1.27 units
respectively, p = 0.25 between groups).
Conclusions: The intervention effect observed at the 6-month follow-up on the composite score was not
maintained at the 12-month follow-up, with no effect on FMI being observed at either follow-up. Future studies
using mHealth are needed to investigate how changes in obesity related markers in young children can be
maintained over longer time periods.The MINISTOP project was funded by the Swedish Research Council (project
no. 2012–2883), the Swedish Research Council for Health, Working Life and
Welfare (2012–0906), Bo and Vera Axson Johnsons Foundation, and
Karolinska Institutet (M.L.). C.D.N was supported by the Swedish Nutrition
Foundation and S.S was funded by the Seaver Foundation. None of the
funding bodies had any contributions or influence in the design of the
study, data collection, analysis, interpretation of the data, or the writing of
the manuscript
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