764 research outputs found
Crystal Structure of FePb 4 Sb 6 Se 14 and its Structural Relationship with FePb 3 Sb 4 Se 10
Single crystals of FePb 4 Sb 6 Se 14 , were obtained from solidâstate combination of high purity elemental powders at 873K for three days. Single crystal Xâray structure determination revealed that the compound crystallizes in the monoclinic space group P 2 1 / c (no. 14) and adopts the structure of Jamesonite (FePb 4 Sb 6 S 14 ). The structure contains two crystallographically independent lead atoms with monocapped and bicapped trigonal prismatic coordinations, three antimony atoms located in a distorted octahedral environment and one iron atom occupying a flattened octahedral coordination. Neighboring monocapped and bicapped trigonal prims around lead atoms share faces and edges to build a corrugated layer parallel to the ac plane. Octahedrally coordinated antimony atoms share edges to form oneâdimensional (1D) {SbSe} â ribbons connecting adjacent corrugated layers. The distortion of the octahedral coordination around antimony atoms within the {SbSe} â ribbons with the longest bond pointing towards the center of the ribbon, suggests the stereochemical activity of antimony loneâpairs with their electron clouds pointing towards the center of the {SbSe} â ribbon. The three dimensional framework resulting from the connectivity between the corrugated layers and the {SbSe} â ribbons, contains isolated cylindrical voids parallel to [100] which are filled by a 1D Fe n Se 4n+2 straight chain of edgeâsharing FeSe 6 octahedra. The crystal structure of FePb 4 Sb 6 Se 14 is closely related to that of FePb 3 Sb 4 Se 10 as they are formed by similar building units with different sizes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95198/1/2549_ftp.pd
The I-mode confinement regime at ASDEX Upgrade: global propert ies and characterization of strongly intermittent density fluctuations
Properties of the IÂmode confinement regime on the ASDEX Upgrade tokamak are
summarized. A weak dependence of the power threshold for the LÂI transition on the toroidal
magnetic field strength is found. During improved confinement, the edge radial electric field
well deepens. Stability calculations show that the IÂmode pedestal is peelingÂballooning stable.
Turbulence investigations reveal strongly intermittent density fluctuations linked to the weakly
coherent mode in the confined plasma, which become stronger as the confinement quality
increases. Across all investigated structure sizes (
â
â„
k
5
â
12 cm
â
1
, with
â„
k
the perpendicular
wavenumber of turbulent density fluctuations), the intermittent turbulence bursts are observed.
Comparison with bolometry data shows that they move poloidally toward the XÂpoint and
finally end up in the divertor. This might be indicative that they play a role in inhibiting the
density profile growth, such that no pedestal is formed in the edge density profile.European Union (EUROfusion 633053)European Union (EUROfusion AWP15ÂENRÂ09/IPPÂ02
Characterising The Atmospheric Dynamics Of HD209458b-like Hot Jupiters Using AI Driven Image Recognition/Categorisation
In-order to understand the results of recent observations of exoplanets,
models have become increasingly complex. Unfortunately this increases both the
computational cost and output size of said models. We intend to explore if
AI-image-recognition can alleviate this burden. We used DYNAMICO to run a
series of HD209458-like models with different orbital-radii. Training data for
a number of features of interest was selected from the initial outputs of these
models. This was used to train a pair of multi-categorisation
convolutional-neural-networks (CNN), which we applied to our
outer-atmosphere-equilibrated models. The features detected by our CNNs
revealed that our models fall into two regimes: models with a shorter
orbital-radii exhibit significant global mixing which shapes the entire
atmospheres dynamics. Whereas, models with longer orbital-radii exhibit
negligible mixing except at mid-pressures. Here, the initial non-detection of
any trained features revealed a surprise: a night-side hot-spot. Analysis
suggests that this occurs when rotational influence is sufficiently weak that
divergent flows from the day-side to the night-side dominate over
rotational-driven transport, such as the equatorial jet. We suggest that
image-classification may play an important role in future, computational,
atmospheric studies. However special care must be paid to the data feed into
the model, from the colourmap, to training the CNN on features with enough
breadth and complexity that the CNN can learn to detect them. However, by using
preliminary-studies and prior-models, this should be more than achievable for
future exascale calculations, allowing for a significant reduction in future
workloads and computational resources.Comment: Accepted for publication in Ap
1H and 13C NMR assignments for a series of DielsâAlder adducts of anthracene and 9âsubstituted anthracenes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111949/1/mrc4268.pd
Septic AKI in ICU patients. diagnosis, pathophysiology, and treatment type, dosing, and timing: a comprehensive review of recent and future developments
Evidence is accumulating showing that septic acute kidney injury (AKI) is different from non-septic AKI. Specifically, a large body of research points to apoptotic processes underlying septic AKI. Unravelling the complex and intertwined apoptotic and immuno-inflammatory pathways at the cellular level will undoubtedly create new and exciting perspectives for the future development (e.g., caspase inhibition) or refinement (specific vasopressor use) of therapeutic strategies. Shock complicating sepsis may cause more AKI but also will render treatment of this condition in an hemodynamically unstable patient more difficult. Expert opinion, along with the aggregated results of two recent large randomized trials, favors continuous renal replacement therapy (CRRT) as preferential treatment for septic AKI (hemodynamically unstable). It is suggested that this approach might decrease the need for subsequent chronic dialysis. Large-scale introduction of citrate as an anticoagulant most likely will change CRRT management in intensive care units (ICU), because it not only significantly increases filter lifespan but also better preserves filter porosity. A possible role of citrate in reducing mortality and morbidity, mainly in surgical ICU patients, remains to be proven. Also, citrate administration in the predilution mode appears to be safe and exempt of relevant side effects, yet still requires rigorous monitoring. Current consensus exists about using a CRRT dose of 25 ml/kg/h in non-septic AKI. However, because patients should not be undertreated, this implies that doses as high as 30 to 35 ml/kg/h must be prescribed to account for eventual treatment interruptions. Awaiting results from large, ongoing trials, 35 ml/kg/h should remain the standard dose in septic AKI, particularly when shock is present. To date, exact timing of CRRT is not well defined. A widely accepted composite definition of timing is needed before an appropriate study challenging this major issue can be launched
Nomenclature for renal replacement therapy and blood purification techniques in critically ill patients: practical applications
This article reports the conclusions of the second part of a consensus expert conference on the nomenclature of renal replacement therapy (RRT) techniques currently utilized to manage acute kidney injury and other organ dysfunction syndromes in critically ill patients. A multidisciplinary approach was taken to achieve harmonization of definitions, components, techniques, and operations of the extracorporeal therapies. The article describes the RRT techniques in detail with the relevant technology, procedures, and phases of treatment and key aspects of volume management/fluid balance in critically ill patients. In addition, the article describes recent developments in other extracorporeal therapies, including therapeutic plasma exchange, multiple organ support therapy, liver support, lung support, and blood purification in sepsis. This is a consensus report on nomenclature harmonization in extracorporeal blood purification therapies, such as hemofiltration, plasma exchange, multiple organ support therapies, and blood purification in sepsis
GATE : a simulation toolkit for PET and SPECT
Monte Carlo simulation is an essential tool in emission tomography that can
assist in the design of new medical imaging devices, the optimization of
acquisition protocols, and the development or assessment of image
reconstruction algorithms and correction techniques. GATE, the Geant4
Application for Tomographic Emission, encapsulates the Geant4 libraries to
achieve a modular, versatile, scripted simulation toolkit adapted to the field
of nuclear medicine. In particular, GATE allows the description of
time-dependent phenomena such as source or detector movement, and source decay
kinetics. This feature makes it possible to simulate time curves under
realistic acquisition conditions and to test dynamic reconstruction algorithms.
A public release of GATE licensed under the GNU Lesser General Public License
can be downloaded at the address http://www-lphe.epfl.ch/GATE/
ÎČ-Lactam Resistance Response Triggered by Inactivation of a Nonessential Penicillin-Binding Protein
It has long been recognized that the modification of penicillin-binding proteins (PBPs) to reduce their affinity for ÎČ-lactams is an important mechanism (target modification) by which Gram-positive cocci acquire antibiotic resistance. Among Gram-negative rods (GNR), however, this mechanism has been considered unusual, and restricted to clinically irrelevant laboratory mutants for most species. Using as a model Pseudomonas aeruginosa, high up on the list of pathogens causing life-threatening infections in hospitalized patients worldwide, we show that PBPs may also play a major role in ÎČ-lactam resistance in GNR, but through a totally distinct mechanism. Through a detailed genetic investigation, including whole-genome analysis approaches, we demonstrate that high-level (clinical) ÎČ-lactam resistance in vitro, in vivo, and in the clinical setting is driven by the inactivation of the dacB-encoded nonessential PBP4, which behaves as a trap target for ÎČ-lactams. The inactivation of this PBP is shown to determine a highly efficient and complex ÎČ-lactam resistance response, triggering overproduction of the chromosomal ÎČ-lactamase AmpC and the specific activation of the CreBC (BlrAB) two-component regulator, which in turn plays a major role in resistance. These findings are a major step forward in our understanding of ÎČ-lactam resistance biology, and, more importantly, they open up new perspectives on potential antibiotic targets for the treatment of infectious diseases
Quantification of the efficiency of treatment of Anopheles gambiae breeding sites with petroleum products by local communities in areas of insecticide resistance in the Republic of Benin
<p>Abstract</p> <p>Background</p> <p>The emergence of <it>Anopheles </it>populations capable of withstanding lethal doses of insecticides has weakened the efficacy of most insecticide based strategies of vector control and, has highlighted the need for developing new insecticidal molecules or, improving the efficacy of existing insecticides or abandoning those to which resistance has emerged. The use of petroleum products (PP) against mosquito larvae had an immense success during early programmes of malaria control, but these compounds were abandoned and replaced in the 1950s by synthetic insecticides probably because of the high performances given by these new products. In the current context of vector resistance, it is important to elucidate the empirical use of PP by quantifying their efficiencies on resistant strains of <it>Anopheles</it>.</p> <p>Methods</p> <p>Larvae of <it>Anopheles </it>Ladji a local resistant strain were exposed to increasing concentrations of various PP (kerosene, petrol and engine oils) for 24 hours and the lethal activities recorded. The highest concentration (HiC) having no lethal activity (also referred as the NOEL or no effect level) and the lowest concentration (LoC<sub>100</sub>) yielding 100% mortality were rated for each PP on the Ladji strain. Prior to laboratory analysis, KAP studies were conducted in three traditional communities were insecticide resistance is clearly established to confirm the use of PP against mosquitoes.</p> <p>Results</p> <p>Laboratory analysis of petrol, kerosene and engine oils, clearly established their lethal activities on resistant strains of <it>Anopheles </it>larvae. Contrary to existing references, this research revealed that exposed larvae of <it>Anopheles </it>were mostly killed by direct contact toxicity and not by suffocation as indicated in some earlier reports.</p> <p>Conclusion</p> <p>This research could serve as scientific basis to backup the empirical utilisation of PP on mosquito larvae and to envisage possibilities of using PP in some traditional settings where <it>Anopheles </it>have developed resistance to currently used insecticides.</p
Measurement of Receptor-Activated Phosphoinositide Turnover in Rat Brain: Nonequivalence of Inositol Phosphate and CDP-Diacylglycerol Formation
Two methods for the measurement of receptor-activated phosphoinositide turnover were evaluated for their degree of correspondence in slices of rat brain; they involved the Li + -dependent accumulations of either [ 3 H]-inositol-labeled inositol phosphates or [ 3 H]cytidine-labeled CDP-diacylglycerol. In contrast to the expectation that the ratio of these two responses would remain approximately constant, varying degrees of correspondence were obtained. The two extremes are exemplified by carbachol, which elicited large increases in both inositol phosphate and CDP-diacylglycerol labeling, and endothelin, which gave a robust inositol phosphate response with little or no accumulation of 3 H-CDP-diacylglycerol. No instance of the presence of the latter response in the absence of 3 H-inositol phosphate accumulation was observed. Measurement of 3 H-CDP-diacylglycerol accumulation thus may add additional insight into the regulation of phosphoinositide turnover and the complex actions of Li + .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66135/1/j.1471-4159.1993.tb03258.x.pd
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