3,042 research outputs found
Acute Respiratory Distress Syndrome: Response
The epistolic response to other letters published in The New England Journal of Medicine 337 (2017), no. 19, pp. 1903-1905, as a result of the Review Article: B. Taylor Thompson, Rachel C. Chambers, Kathleen D. Liu, Acute Respiratory Distress Syndrome, The New England of Medicine 377, no. 6, (2017), pp. 562-572
Acute Respiratory Distress Syndrome.
Fifty years ago, Ashbaugh and colleagues described 12 patients with tachypnea, refractory hypoxemia, and diffuse opacities on chest radiographs after infection or trauma.1 Prominent hyaline membranes were seen lining the alveolar spaces of the lungs in 6 of the 7 patients who died, findings previously thought to be specific for the respiratory distress syndrome of the newborn. Thus, the term adult (later changed to acute) respiratory distress syndrome (ARDS) was proposed.
Since ARDS was last reviewed in the Journal, 17 years ago,2 substantial progress has been made in the care of affected patients and those at risk for the disorder, with reductions in both incidence and mortality. However, ARDS remains a relatively common and lethal or disabling syndrome. In a recent international study involving 29,144 patients,3 10% of all patients admitted to the intensive care unit (ICU) and 23% of mechanically ventilated patients had ARDS. Mortality in the subgroup of patients with severe ARDS was 46%.3 Patients who survive this disorder are at high risk for cognitive decline, depression, post-traumatic stress disorder, and persistent skeletal-muscle weakness
Networks and regional economic growth: a spatial analysis of knowledge ties
In recent years, increased attention has been given to role of inter-organisational knowledge networks in promoting regional economic growth. Nevertheless, the empirical evidence base concerning the extent to which inter-organisational knowledge networks influence regional growth is at best patchy. This paper utilises a panel data regression approach to undertake an empirical analysis of economic growth across regions of the UK. Drawing on the concept of network capital, significant differences in the stocks of network capital and flows of knowledge within and across regions are found, which are significantly associated with regional rates of economic growth. The analysis finds that both inter- and intra-regional networks shape regional growth processes, highlighting the role of both embedded localised linkages and the importance of accessing more geographically distant knowledge. The study adds weight to the suggestion that one of the most interesting implications of endogenous growth theory relates to the impact of the spatial organisation of regions on flows of knowledge. It is concluded that the adoption of a relational approach to understanding differing economic geographies indicates that network systems are a key component of the regional development mix
Exoplanet Catalogues
One of the most exciting developments in the field of exoplanets has been the
progression from 'stamp-collecting' to demography, from discovery to
characterisation, from exoplanets to comparative exoplanetology. There is an
exhilaration when a prediction is confirmed, a trend is observed, or a new
population appears. This transition has been driven by the rise in the sheer
number of known exoplanets, which has been rising exponentially for two decades
(Mamajek 2016). However, the careful collection, scrutiny and organisation of
these exoplanets is necessary for drawing robust, scientific conclusions that
are sensitive to the biases and caveats that have gone into their discovery.
The purpose of this chapter is to discuss and demonstrate important
considerations to keep in mind when examining or constructing a catalogue of
exoplanets. First, we introduce the value of exoplanetary catalogues. There are
a handful of large, online databases that aggregate the available exoplanet
literature and render it digestible and navigable - an ever more complex task
with the growing number and diversity of exoplanet discoveries. We compare and
contrast three of the most up-to-date general catalogues, including the data
and tools that are available. We then describe exoplanet catalogues that were
constructed to address specific science questions or exoplanet discovery space.
Although we do not attempt to list or summarise all the published lists of
exoplanets in the literature in this chapter, we explore the case study of the
NASA Kepler mission planet catalogues in some detail. Finally, we lay out some
of the best practices to adopt when constructing or utilising an exoplanet
catalogue.Comment: 14 pages, 6 figures. Invited review chapter, to appear in "Handbook
of Exoplanets", edited by H.J. Deeg and J.A. Belmonte, section editor N.
Batalh
Acute Respiratory Distress Syndrome:The Berlin Definition
The acute respiratory distress syndrome (ARDS) was defined in 1994 by the American-European Consensus Conference (AECC); since then, issues regarding the reliability and validity of this definition have emerged. Using a consensus process, a panel of experts convened in 2011 (an initiative of the European
Society of Intensive Care Medicine endorsed by the American Thoracic Society and the Society of Critical Care Medicine) developed the Berlin Definition, focusing on feasibility, reliability, validity, and objective evaluation of its performance. A draft definition proposed 3 mutually exclusive categories
of ARDS based on degree of hypoxemia: mild (200 mm HgPaO2/FIO2300 mmHg), moderate (100mmHgPaO2/FIO2200mmHg), and severe (PaO2/FIO2100mmHg) and 4 ancillary variables for severe ARDS: radiographic severity,
respiratory system compliance (40 mL/cm H2O), positive endexpiratory pressure (10 cm H2O), and corrected expired volume per minute(10 L/min). The draft Berlin Definition was empirically evaluated using patientlevel meta-analysis of 4188 patients with ARDS from 4 multicenter clinical data
sets and 269 patients with ARDS from 3 single-center data sets containing physiologic information. The 4 ancillary variables did not contribute to the predictive validity of severe ARDS for mortality and were removed from the definition.
Using the Berlin Definition, stages of mild, moderate, and severe ARDS were associated with increased mortality (27%;95%CI, 24%-30%; 32%;95% CI, 29%-34%; and 45%; 95% CI, 42%-48%, respectively; P.001) and increased
median duration of mechanical ventilation in survivors (5 days; interquartile [IQR], 2-11; 7 days; IQR, 4-14; and 9 days; IQR, 5-17, respectively;
P.001). Compared with the AECC definition, the final Berlin Definition had better predictive validity for mortality, with an area under the receiver operating curve of 0.577 (95% CI, 0.561-0.593) vs 0.536 (95% CI, 0.520-0.553;
P.001). This updated and revised Berlin Definition for ARDS addresses a number of the limitations of the AECC definition. The approach of combining consensus discussions with empirical evaluation may serve as a model to create more accurate, evidence-based, critical illness syndrome definitions and to better
inform clinical care, research, and health services planning
On Semiclassical Limits of String States
We explore the relation between classical and quantum states in both open and
closed (super)strings discussing the relevance of coherent states as a
semiclassical approximation. For the closed string sector a gauge-fixing of the
residual world-sheet rigid translation symmetry of the light-cone gauge is
needed for the construction to be possible. The circular target-space loop
example is worked out explicitly.Comment: 12 page
The Dawn of Open Access to Phylogenetic Data
The scientific enterprise depends critically on the preservation of and open
access to published data. This basic tenet applies acutely to phylogenies
(estimates of evolutionary relationships among species). Increasingly,
phylogenies are estimated from increasingly large, genome-scale datasets using
increasingly complex statistical methods that require increasing levels of
expertise and computational investment. Moreover, the resulting phylogenetic
data provide an explicit historical perspective that critically informs
research in a vast and growing number of scientific disciplines. One such use
is the study of changes in rates of lineage diversification (speciation -
extinction) through time. As part of a meta-analysis in this area, we sought to
collect phylogenetic data (comprising nucleotide sequence alignment and tree
files) from 217 studies published in 46 journals over a 13-year period. We
document our attempts to procure those data (from online archives and by direct
request to corresponding authors), and report results of analyses (using
Bayesian logistic regression) to assess the impact of various factors on the
success of our efforts. Overall, complete phylogenetic data for ~60% of these
studies are effectively lost to science. Our study indicates that phylogenetic
data are more likely to be deposited in online archives and/or shared upon
request when: (1) the publishing journal has a strong data-sharing policy; (2)
the publishing journal has a higher impact factor, and; (3) the data are
requested from faculty rather than students. Although the situation appears
dire, our analyses suggest that it is far from hopeless: recent initiatives by
the scientific community -- including policy changes by journals and funding
agencies -- are improving the state of affairs
High levels of contamination and antimicrobial-resistant non-typhoidal Salmonella serovars on pig and poultry farms in the Mekong Delta of Vietnam.
We investigated the prevalence, diversity, and antimicrobial resistance (AMR) profiles of non-typhoidal Salmonella (NTS) and associated risk factors on 341 pig, chicken, and duck farms in Dong Thap province (Mekong Delta, Vietnam). Sampling was stratified by species, district (four categories), and farm size (three categories). Pooled faeces, collected using boot swabs, were tested using ISO 6575: 2002 (Annex D). Isolates were serogrouped; group B isolates were tested by polymerase chain reaction to detect S. Typhimurium and (monophasic) serovar 4,[5],12:i:- variants. The farm-level adjusted NTS prevalence was 64·7%, 94·3% and 91·3% for chicken, duck and pig farms, respectively. Factors independently associated with NTS were duck farms [odds ratio (OR) 21·2], farm with >50 pigs (OR 11·9), pig farm with 5-50 pigs (OR 4·88) (vs. chickens), and frequent rodent sightings (OR 2·3). Both S. Typhimurium and monophasic S. Typhimurium were more common in duck farms. Isolates had a high prevalence of resistance (77·6%) against tetracycline, moderate resistance (20-30%) against chloramphenicol, sulfamethoxazole-trimethoprim, ampicillin and nalidixic acid, and low resistance (<5%) against ciprofloxacin and third-generation cephalosporins. Multidrug resistance (resistance against ⩾3 classes of antimicrobial) was independently associated with monophasic S. Typhimurium and other group B isolates (excluding S. Typhimurium) and pig farms. The unusually high prevalence of NTS on Mekong Delta farms poses formidable challenges for control
Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip
Vascular plants rely on differences of osmotic pressure to export sugars from
regions of synthesis (mature leaves) to sugar sinks (roots, fruits). In this
process, known as M\"unch pressure flow, the loading of sugars from
photosynthetic cells to the export conduit (the phloem) is crucial, as it sets
the pressure head necessary to power long-distance transport. Whereas most
herbaceous plants use active mechanisms to increase phloem concentration above
that of the photosynthetic cells, in most tree species, for which transport
distances are largest, loading seems to occur via passive symplastic diffusion
from the mesophyll to the phloem. Here, we use a synthetic microfluidic model
of a passive loader to explore the nonlinear dynamics that arise during export
and determine the ability of passive loading to drive long-distance transport.
We first demonstrate that in our device, phloem concentration is set by the
balance between the resistances to diffusive loading from the source and
convective export through the phloem. Convection-limited export corresponds to
classical models of M\"unch transport, where phloem concentration is close to
that of the source; in contrast, diffusion-limited export leads to small phloem
concentrations and weak scaling of flow rates with the hydraulic resistance. We
then show that the effective regime of convection-limited export is predominant
in plants with large transport resistances and low xylem pressures. Moreover,
hydrostatic pressures developed in our synthetic passive loader can reach
botanically relevant values as high as 10 bars. We conclude that passive
loading is sufficient to drive long-distance transport in large plants, and
that trees are well suited to take full advantage of passive phloem loading
strategies
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