1,828 research outputs found
Simulated drug administration: An emerging tool for teaching clinical pharmacology during anesthesiology training
A thorough understanding of the dose-response relationship is required for optimizing the efficacy of anesthetics while minimizing adverse drug effects.(1) Nowadays, except for the inhaled anesthetics (for which end-tidal concentrations can be measured online), most of the drugs used in clinical anesthesia are administered using standard dosing guidelines, without giving due consideration to their pharmacokinetics and dynamics in guiding their administration. Various studies have found that introducing pharmacokinetics and pharmacodynamics as part of the inputs in clinical anesthesiology could lead to better patient care.(2) With this in mind, it is extremely important that clinicians understand and apply the principles of clinical pharmacology that determine the time course of a drug's disposition and effect.
Clinical pharmacology is one of the most challenging topics to teach in anesthesiology. The development of simulators to illustrate the time course of a drug's disposition and effect provides online visualization of pharmacokinetic pharmacodynamic information during the clinical use of anesthetics. The aim of this review is to discuss the importance of simulation as a clinical pharmacology teaching tool for trainees in anesthesiology
San Francisco Bay Area corporate history : a selected annotated bibliography
Human activities, among which dredging and land use change in river basins,
are altering estuarine ecosystems. These activities may result in changes in
sedimentary processes, affecting biodiversity of sediment macrofauna. As
macrofauna controls sediment chemistry and fluxes of energy and matter between
water column and sediment, changes in the structure of macrobenthic
communities could affect the functioning of an entire ecosystem. We assessed
the impact of sediment deposition on intertidal macrobenthic communities and
on rates of an important ecosystem function, i.e. sediment community oxygen
consumption (SCOC). An experiment was performed with undisturbed sediment
samples from the Scheldt river estuary (SW Netherlands). The samples were
subjected to four sedimentation regimes: one control and three with a
deposited sediment layer of 1, 2 or 5 cm. Oxygen consumption was measured
during incubation at ambient temperature. Luminophores applied at the
surface, and a seawater–bromide mixture, served as tracers for bioturbation
and bio-irrigation, respectively. After incubation, the macrofauna was
extracted, identified, and counted and then classified into functional groups
based on motility and sediment reworking capacity. Total macrofaunal
densities dropped already under the thinnest deposits. The most affected
fauna were surficial and low-motility animals, occurring at high densities in
the control. Their mortality resulted in a drop in SCOC, which decreased
steadily with increasing deposit thickness, while bio-irrigation and
bioturbation activity showed increases in the lower sediment deposition
regimes but decreases in the more extreme treatments. The initial increased
activity likely counteracted the effects of the drop in low-motility, surficial
fauna densities, resulting in a steady rather than sudden fall in oxygen
consumption. We conclude that the functional identity in terms of motility
and sediment reworking can be crucial in our understanding of the regulation
of ecosystem functioning and the impact of habitat alterations such as
sediment deposition
Module networks revisited: computational assessment and prioritization of model predictions
The solution of high-dimensional inference and prediction problems in
computational biology is almost always a compromise between mathematical theory
and practical constraints such as limited computational resources. As time
progresses, computational power increases but well-established inference
methods often remain locked in their initial suboptimal solution. We revisit
the approach of Segal et al. (2003) to infer regulatory modules and their
condition-specific regulators from gene expression data. In contrast to their
direct optimization-based solution we use a more representative centroid-like
solution extracted from an ensemble of possible statistical models to explain
the data. The ensemble method automatically selects a subset of most
informative genes and builds a quantitatively better model for them. Genes
which cluster together in the majority of models produce functionally more
coherent modules. Regulators which are consistently assigned to a module are
more often supported by literature, but a single model always contains many
regulator assignments not supported by the ensemble. Reliably detecting
condition-specific or combinatorial regulation is particularly hard in a single
optimum but can be achieved using ensemble averaging.Comment: 8 pages REVTeX, 6 figure
Layer charge instability in unbalanced bilayer systems in the quantum Hall regime
Measurements in GaAs hole bilayers with unequal layer densities reveal a
pronounced magneto-resistance hysteresis at the magnetic field positions where
either the majority or minority layer is at Landau level filling factor one. At
a fixed field in the hysteretic regions, the resistance exhibits an unusual
time dependence, consisting of random, bidirectional jumps followed by slow
relaxations. These anomalies are apparently caused by instabilities in the
charge distribution of the two layers.Comment: 4 pages, 4 figure
MarkerMiner 1.0: a new application for phylogenetic marker development using angiosperm transcriptomes
Premise of the study: Targeted sequencing using next-generation sequencing (NGS) platforms offers enormous potential for plant systematics by enabling economical acquisition of multilocus data sets that can resolve difficult phylogenetic problems. However, because discovery of single-copy nuclear (SCN) loci from NGS data requires both bioinformatics skills and access to high-performance computing resources, the application of NGS data has been limited.
Methods and Results: We developed MarkerMiner 1.0, a fully automated, open-access bioinformatic workflow and application for discovery of SCN loci in angiosperms. Our new tool identified as many as 1993 SCN loci from transcriptomic data sampled as part of four independent test cases representing marker development projects at different phylogenetic scales.
Conclusions: MarkerMiner is an easy-to-use and effective tool for discovery of putative SCN loci. It can be run locally or via the Web, and its tabular and alignment outputs facilitate efficient downstream assessments of phylogenetic utility, locus selection, intron-exon boundary prediction, and primer or probe development
Spins, charges and currents at Domain Walls in a Quantum Hall Ising Ferromagnet
We study spin textures in a quantum Hall Ising ferromagnet. Domain walls
between ferro and unpolarized states at are analyzed with a functional
theory supported by a microscopic calculation. In a neutral wall, Hartree
repulsion prevents the appearance of a fan phase provoked by a negative
stiffness. For a charged system, electrons become trapped as solitons at the
domain wall. The size and energy of the solitons are determined by both Hartree
and spin-orbit interactions. Finally, we discuss how electrical transport takes
place through the domain wall.Comment: 4 pages, 3 figures include
Caged Black Holes: Black Holes in Compactified Spacetimes II - 5d Numerical Implementation
We describe the first convergent numerical method to determine static black
hole solutions (with S^3 horizon) in 5d compactified spacetime. We obtain a
family of solutions parametrized by the ratio of the black hole size and the
size of the compact extra dimension. The solutions satisfy the demanding
integrated first law. For small black holes our solutions approach the 5d
Schwarzschild solution and agree very well with new theoretical predictions for
the small corrections to thermodynamics and geometry. The existence of such
black holes is thus established. We report on thermodynamical (temperature,
entropy, mass and tension along the compact dimension) and geometrical
measurements. Most interestingly, for large masses (close to the
Gregory-Laflamme critical mass) the scheme destabilizes. We interpret this as
evidence for an approach to a physical tachyonic instability. Using
extrapolation we speculate that the system undergoes a first order phase
transition.Comment: 42 pages, 19 eps figures; v2: 3 references added, version to appear
in Phys.Rev.
Functional trait responses to sediment deposition reduce macrofauna-mediated ecosystem functioning in an estuarine mudflat
Human activities, among which dredging and land use change in river basins, are altering estuarine ecosystems. These activities may result in changes in sedimentary processes, affecting biodiversity of sediment macrofauna. As macrofauna controls sediment chemistry and fluxes of energy and matter between water column and sediment, changes in the structure of macrobenthic communities could affect the functioning of an entire ecosystem. We assessed the impact of sediment deposition on intertidal macrobenthic communities and on rates of an important ecosystem function, i.e. sediment community oxygen consumption (SCOC). An experiment was performed with undisturbed sediment samples from the Scheldt river estuary (SW Netherlands). The samples were subjected to four sedimentation regimes: one control and three with a deposited sediment layer of 1, 2 or 5 cm. Oxygen consumption was measured during incubation at ambient temperature. Luminophores applied at the surface, and a seawater–bromide mixture, served as tracers for bioturbation and bio-irrigation, respectively. After incubation, the macrofauna was extracted, identified, and counted and then classified into functional groups based on motility and sediment reworking capacity. Total macrofaunal densities dropped already under the thinnest deposits. The most affected fauna were surficial and low-motility animals, occurring at high densities in the control. Their mortality resulted in a drop in SCOC, which decreased steadily with increasing deposit thickness, while bio-irrigation and bioturbation activity showed increases in the lower sediment deposition regimes but decreases in the more extreme treatments. The initial increased activity likely counteracted the effects of the drop in low-motility, surficial fauna densities, resulting in a steady rather than sudden fall in oxygen consumption. We conclude that the functional identity in terms of motility and sediment reworking can be crucial in our understanding of the regulation of ecosystem functioning and the impact of habitat alterations such as sediment deposition
O3/O7 Orientifold Truncations and Very Special Quaternionic-Kaehler Geometry
We study the orientifold truncation that arises when compactifying type II
string theory on Calabi-Yau orientifolds with O3/O7-planes, in the context of
supergravity. We look at the N=2 to N=1 reduction of the hypermultiplet sector
of N=2 supergravity under the truncation, for the case of very special
quaternionic-Kaehler target space geometry. We explicitly verify the Kaehler
structure of the truncated spaces, and we study the truncated isometry algebra.
For symmetric special quaternionic spaces, we give a complete overview of the
spaces one finds after truncation. We also find new examples of dual Kaehler
spaces, that give rise to flat potentials in N=1 supergravity.Comment: 25 pages, LaTeX, v2:curvature tensor of the dual symmetric spaces
calculated, section 7 expanded, references added, v3:few typos fixed, version
to appear in Class.Quantum Gravit
Analytical Tachyonic Lump Solutions in Open Superstring Field Theory
We construct a classical solution in the GSO(-) sector in the framework of a
Wess-Zumino-Witten-like open superstring field theory on a non-BPS D-brane. We
use an su(2) supercurrent, which is obtained by compactifying a direction to a
circle with the critical radius, in order to get analytical tachyonic lump
solutions to the equation of motion. By investigating the action expanded
around a solution we find that it represents a deformation from a non-BPS
D-brane to a D-brane-anti-D-brane system at the critical value of a parameter
which is contained in classical solutions. Although such a process was
discussed in terms of boundary conformal field theory before, our study is
based on open superstring field theory including interaction terms.Comment: 17 pages, references adde
- …