1,804 research outputs found
Response to the authors:Feasibility of an alternative, physiologic, individualized open-lung approach to high-frequency oscillatory ventilation in children Response
Physiological modes of action across species and toxicants : the key to predictive ecotoxicology
As ecotoxicologists we strive for a better understanding of how chemicals affect our environment. Humanity needs tools to identify those combinations of man-made chemicals and organisms most likely to cause problems. In other words: which of the millions of species are at risk from pollution? And which of the tens of thousands of chemicals contribute most to the risk? We identified our poor knowledge on physiological modes of action (how a chemical affects the energy allocation in an organism), and how they vary across species and toxicants, as a major knowledge gap. We also find that the key to predictive ecotoxicology is the systematic, rigorous characterization of physiological modes of action because that will enable more powerful in vitro to in vivo toxicity extrapolation and in silico ecotoxicology. In the near future, we expect a step change in our ability to study physiological modes of action by improved, and partially automated, experimental methods. Once we have populated the matrix of species and toxicants with sufficient physiological mode of action data we can look for patterns, and from those patterns infer general rules, theory and models
Optimizing cofactor availability for the production of recombinant heme peroxidase in Pichia pastoris
Signatures of Planets in Spatially Unresolved Disks
Main sequence stars are commonly surrounded by debris disks, composed of cold
dust continuously replenished by a reservoir of undetected dust-producing
planetesimals. In a planetary system with a belt of planetesimals (like the
Solar System's Kuiper Belt) and one or more interior giant planets, the
trapping of dust particles in the mean motion resonances with the planets can
create structure in the dust disk, as the particles accumulate at certain
semimajor axes. Sufficiently massive planets may also scatter and eject dust
particles out of a planetary system, creating a dust depleted region inside the
orbit of the planet. In anticipation of future observations of spatially
unresolved debris disks with the Spitzer Space Telescope, we are interested in
studying how the structure carved by planets affects the shape of the disk's
spectral energy distribution (SED), and consequently if the SED can be used to
infer the presence of planets. We numerically calculate the equilibrium spatial
density distributions and SEDs of dust disks originated by a belt of
planetesimals in the presence of interior giant planets in different planetary
configurations, and for a representative sample of chemical compositions. The
dynamical models are necessary to estimate the enhancement of particles near
the mean motion resonances with the planets, and to determine how many
particles drift inside the planet's orbit. Based on the SEDs and predicted
colors we discuss what types of planetary systems can be
distinguishable from one another and the main parameter degeneracies in the
model SEDs.Comment: 40 pages (pre-print form), including 16 figures. Published in ApJ
200
Next-to-leading order QCD corrections to Higgs boson production in association with a photon via weak-boson fusion at the LHC
Higgs boson production in association with a hard central photon and two
forward tagging jets is expected to provide valuable information on Higgs boson
couplings in a range where it is difficult to disentangle weak-boson fusion
processes from large QCD backgrounds. We present next-to-leading order QCD
corrections to Higgs production in association with a photon via weak-boson
fusion at a hadron collider in the form of a flexible parton-level Monte Carlo
program. The QCD corrections to integrated cross sections are found to be small
for experimentally relevant selection cuts, while the shape of kinematic
distributions can be distorted by up to 20% in some regions of phase space.
Residual scale uncertainties at next-to-leading order are at the few-percent
level.Comment: 17 pages, 7 figures, 1 tabl
NICMOS Spectrophotometry and Models for A-Stars
Absolute flux distributions for eight stars are well measured from 0.8-2.5mu
m with NICMOS grism spectrophotometry at a resolution of R~100 and an accuracy
of 1-2%. These SEDs are fit with Castelli & Kurucz model atmospheres; and the
results are compared with the Cohen-Walker-Witteborn (CWW) template models for
the same stars. In some cases, the T_{eff}, log g, and log z parameters of the
best fitting model differ by up to 1000 K from the earlier CWW model. However,
differences in the continua of the modeled IR flux distributions from 0.4-40mu
m are always less than the quoted CWW uncertainty of 5% because of compensating
changes in the measured extinction. At wavelengths longward of the 2.5mu m
NICMOS limit, uncertainties still approach 5%, because A-star models are not
yet perfect. All of these A stars lie in the JWST continuous viewing zone and
will be important absolute flux standards for the 0.8-30mu m JWST wavelength
range.Comment: 20 pages, 6 figures, 2 tables; to be published in AJ, 2008 Septembe
Methanol-Driven Oxidative Rearrangement of Biogenic Furans - Enzyme Cascades vs. Photobiocatalysis
The oxidative ring expansion of bio-derived furfuryl alcohols to densely functionalized six-membered O-heterocycles represents an attractive strategy in the growing network of valorization routes to synthetic building blocks out of the lignocellulosic biorefinery feed. In this study, two scenarios for the biocatalytic Achmatowicz-type rearrangement using methanol as terminal sacrificial reagent have been evaluated, comparing multienzymatic cascade designs with a photo-bio-coupled activation pathway.Peer reviewe
Hemodynamic Effects of a High-Frequency Oscillatory Ventilation Open-Lung Strategy in Critically Ill Children With Acquired or Congenital Cardiac Disease
OBJECTIVES: To study the hemodynamic consequences of an open-lung high-frequency oscillatory ventilation (HFOV) strategy in patients with an underlying cardiac anomaly with or without intracardiac shunt or primary pulmonary hypertension with severe lung injury.DESIGN: Secondary analysis of prospectively collected data.SETTING: Medical-surgical PICU.PATIENTS: Children less than 18 years old with cardiac anomalies (± intracardiac shunt) or primary pulmonary hypertension.INTERVENTIONS: None.MEASUREMENTS AND MAIN RESULTS: Data from 52 subjects were analyzed, of whom 39 of 52 with cardiac anomaly (23/39 with intracardiac shunt) and 13 of 52 with primary pulmonary hypertension. Fourteen patients were admitted postoperatively, and 26 patients were admitted with acute respiratory failure. Five subjects (9.6%) were canulated for ECMO (of whom four for worsening respiratory status). Ten patients (19.2%) died during PICU stay. Median conventional mechanical ventilation settings prior to HFOV were peak inspiratory pressure 30 cm H 2 O (27-33 cm H 2 O), positive end-expiratory pressure 8 cm H 2 O (6-10 cm H 2 O), and F io2 0.72 (0.56-0.94). After transitioning to HFOV, there was no negative effect on mean arterial blood pressure, central venous pressure, or arterial lactate. Heart rate decreased significantly over time ( p < 0.0001), without group differences. The percentage of subjects receiving a fluid bolus decreased over time ( p = 0.003), especially in those with primary pulmonary hypertension ( p = 0.0155) and without intracardiac shunt ( p = 0.0328). There were no significant differences in the cumulative number of daily boluses over time. Vasoactive Infusion Score did not increase over time. Pa co2 decreased ( p < 0.0002) and arterial pH significantly improved ( p < 0.0001) over time in the whole cohort. Neuromuscular blocking agents were used in all subjects switched to HFOV. Daily cumulative sedative doses were unchanged, and no clinically apparent barotrauma was found.CONCLUSIONS: No negative hemodynamic consequences occurred with an individualized, physiology-based open-lung HFOV approach in patients with cardiac anomalies or primary pulmonary hypertension suffering from severe lung injury.</p
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