721 research outputs found
A "little bit illegalā? Withholding and withdrawing of mechanical ventilation in the eyes of German intensive care physicians
Research questions and background: This study explores a highly controversial issue of medical care in Germany: the decision to withhold or withdraw mechanical ventilation in critically ill patients. It analyzes difficulties in making these decisions and the physicians' uncertainty in understanding the German terminology of Sterbehilfe, which is used in the context of treatment limitation. Used in everyday language, the word Sterbehilfe carries connotations such as helping the patient in the dying process or helping the patient to enter the dying process. Yet, in the legal and ethical discourse Sterbehilfe indicates several concepts: (1) treatment limitation, i.e., withholding or withdrawing life-sustaining treatment (passive Sterbehilfe), (2) the use of medication for symptom control while taking into account the risk of hastening the patient's death (indirekte Sterbehilfe), and (3) measures to deliberately terminate the patient's life (aktive Sterbehilfe). The terminology of Sterbehilfe has been criticized for being too complex and misleading, particularly for practical purposes. Materials and methods An exploratory study based on qualitative interviews was conducted with 28 physicians from nine medical intensive care units in tertiary care hospitals in the German federal state of Baden-Wuerttemberg. The method of data collection was a problem-centered, semi-structured interview using two authentic clinical case examples. In order to shed light on the relation between the physicians' concepts and the ethical and legal frames of reference, we analyzed their way of using the terms passive and aktive Sterbehilfe. Results Generally, the physicians were more hesitant in making decisions to withdraw rather than withhold mechanical ventilation. Almost half of them assumed a categorical prohibition to withdraw any mechanical ventilation and more than one third felt that treatment ought not to be withdrawn at all. Physicians showed specific uncertainty about classifying the withdrawal of mechanical ventilation as passive Sterbehilfe, and had difficulties understanding that terminating ventilation is not basically illegal, but the permissibility of withdrawal depends on the situation. Conclusions The physicians' knowledge and skills in interpreting clinical ethical dilemmas require specific improvement on the one hand; on the other hand, the terms passive and aktive Sterbehilfe are less clear than desirable and not as easy to use in clinical practice. Fear of making unjustified or illegal decisions may motivate physicians to continue (even futile) treatment. Physicians strongly opt for more open discussion about end-of-life care to allow for discontinuation of futile treatment and to reduce conflic
Inference with Constrained Hidden Markov Models in PRISM
A Hidden Markov Model (HMM) is a common statistical model which is widely
used for analysis of biological sequence data and other sequential phenomena.
In the present paper we show how HMMs can be extended with side-constraints and
present constraint solving techniques for efficient inference. Defining HMMs
with side-constraints in Constraint Logic Programming have advantages in terms
of more compact expression and pruning opportunities during inference.
We present a PRISM-based framework for extending HMMs with side-constraints
and show how well-known constraints such as cardinality and all different are
integrated. We experimentally validate our approach on the biologically
motivated problem of global pairwise alignment
Monitoring effects of land cover change on biophysical drivers in rangelands using albedo
This paper explores the relationship between land cover change and albedo, recognized as a regulating ecosystems service. Trends and relationships between land cover change and surface albedo were quantified to characterise catchment water and carbon fluxes, through respectively evapotranspiration (ET) and net primary production (NPP). Moderate resolution imaging spectroradiometer (MODIS) and Landsat satellite data were used to describe trends at catchment and land cover change trajectory level. Peak season albedo was computed to reduce seasonal effects. Different trends were found depending on catchment land management practices, and satellite data used. Although not statistically significant, albedo, NPP, ET and normalised difference vegetation index (NDVI) were all correlated with rainfall. In both catchments, NPP, ET and NDVI showed a weak negative trend, while albedo showed a weak positive trend. Modelled land cover change was used to calculate future carbon storage and water use, with a decrease in catchment carbon storage and water use computed. Grassland, a dominant dormant land cover class, was targeted for land cover change by woody encroachment and afforestation, causing a decrease in albedo, while urbanisation and cultivation caused an increase in albedo. Land cover map error of fragmented transition classes and the mixed pixel effect, affected results, suggesting use of higher-resolution imagery for NPP and ET and albedo as a proxy for land cover
The Clearance of Cyclosporine by Hemodialysis
The pharmacokinetics of cyclosporine were studied in five liver transplant patients when they were on and off hemodialysis. There was no significant difference in the blood clearance of cyclosporine between these two periods. Less than 1 per cent of the dose of cyclosporine was recovered in the dialysate. The mean dialysis clearance was less than 1 ml/min. This represents less than 1 per cent of the total blood clearance of cyclosporine. Dosage alterations of cyclosporine during or after hemodialysis do not appear to be necessary
Structural investigations of the regio- and enantioselectivity of lipases
Although lipases are widely applied for the stereospecific resolution of racemic mixtures of esters, the atomic details of the factors that are responsible for their stereospecificity are largely obscure. We determined the X-ray structures of Pseudomonas cepacia lipase in complex with two enantiopure triglyceride analogues, that closely mimic natural substrates. This allowed an unambiguous view of how the two wings of the boomerang-shaped active site accommodate the acyl and alcohol parts of the triglyceride. The binding groove for the hydrophobic sn-3 fatty acid chain is large and hydrophobic. The cleft for the alcohol moiety is divided in two parts, one tightly binding the sn-2 acyl chain with hydrophilic and hydrophobic interactions, the other more weakly binding the sn-1 fatty acid. The enantioselectivity of Pseudomonas cepacia lipase seems therefore to be predominantly determined by the size and interactions of the sn-2 chain and by the size of the sn-3 chain.
A Rejoinder on Energy versus Impact Indicators
Citation distributions are so skewed that using the mean or any other central
tendency measure is ill-advised. Unlike G. Prathap's scalar measures (Energy,
Exergy, and Entropy or EEE), the Integrated Impact Indicator (I3) is based on
non-parametric statistics using the (100) percentiles of the distribution.
Observed values can be tested against expected ones; impact can be qualified at
the article level and then aggregated.Comment: Scientometrics, in pres
Continuum Surface Energy from a Lattice Model
We investigate connections between the continuum and atomistic descriptions
of deformable crystals, using certain interesting results from number theory.
The energy of a deformed crystal is calculated in the context of a lattice
model with general binary interactions in two dimensions. A new bond counting
approach is used, which reduces the problem to the lattice point problem of
number theory. The main contribution is an explicit formula for the surface
energy density as a function of the deformation gradient and boundary normal.
The result is valid for a large class of domains, including faceted (polygonal)
shapes and regions with piecewise smooth boundaries.Comment: V. 1: 10 pages, no fig's. V 2: 23 pages, no figures. Misprints
corrected. Section 3 added, (new results). Intro expanded, refs added.V 3: 26
pages. Abstract changed. Section 2 split into 2. Section (4) added material.
V 4, 28 pages, Intro rewritten. Changes in Sec.5 (presentation only). Refs
added.V 5,intro changed V.6 address reviewer's comment
Threshold electronic structure at the oxygen K edge of 3d transition metal oxides: a configuration interaction approach
It has been generally accepted that the threshold structure observed in the
oxygen K edge X-ray absorption spectrum in 3d transition metal oxides
represents the electronic structure of the 3d transition metal. There is,
however, no consensus about the correct description. We present an
interpretation, which includes both ground state hybridization and electron
correlation. It is based on a configuration interaction cluster calculation
using a MO6 cluster. The oxygen K edge spectrum is calculated by annihilating a
ligand hole in the ground state and is compared to calculations representing
inverse photoemission experiments in which a 3d transition metal electron is
added. Clear differences are observed related to the amount of ligand hole
created in the ground state. Two "rules" connected to this are discussed.
Comparison with experimental data of some early transition metal compounds is
made and shows that this simple cluster approach explains the experimental
features quite well.Comment: 10 pages, submitted to Phys. Rev. B, tried to make a better PS file
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