948 research outputs found
All Optical Implementation of Multi-Spin Entanglement in a Semiconductor Quantum Well
We use ultrafast optical pulses and coherent techniques to create spin
entangled states of non-interacting electrons bound to donors (at least three)
and at least two Mn2+ ions in a CdTe quantum well. Our method, relying on the
exchange interaction between localized excitons and paramagnetic impurities,
can in principle be applied to entangle a large number of spins.Comment: 17 pages, 3 figure
Homeostasis of metabolites in Escherichia coli on transition from anaerobic to aerobic conditions and the transient secretion of pyruvate
We have developed a method for rapid quenching of samples
taken from chemostat cultures of Escherichia coli that gives
reproducible and reliable measurements of extracellular and
intracellular metabolites by 1H NMR and have applied it
to study the major central metabolites during the transition
from anaerobic to aerobic growth. Almost all metabolites
showed a gradual change after perturbation with air, consistent
with immediate inhibition of pyruvate formate-lyase, dilution
of overflow metabolites and induction of aerobic enzymes.
Surprisingly, although pyruvate showed almost no change
in intracellular concentration, the extracellular concentration
transiently increased. The absence of intracellular accumulation
of pyruvate suggested that one or more glycolytic enzymes
might relocate to the cell membrane. To test this hypothesis,
chromosomal pyruvate kinase (pykF) was modified to express
either PykF-green fluorescent protein or PykF-FLAG fusion
proteins. Measurements showed that PykF-FLAG relocates to
the cell membrane within 5 min of aeration and then slowly
returns to the cytoplasm, suggesting that on aeration, PykF
associates with the membrane to facilitate secretion of pyruvate
to maintain constant intracellular levels
Visualising spatial and social media
In this chapter, we begin by surveying the development of computer graphics as it has influenced the development of the spatial representation of social and economic data, charting the history of computer cartography and geographic information systems (GIS) which have broadened into a wide array of forms for scientific visualisation. With the advent of the World Wide Web and the widespread adoption of graphical user interfaces (GUIs) to most kinds of computer device, visualisation has become central to most sciences and to the dissemination of many kinds of data and information. We divide our treatment of this domain according to three themes. First we examine how the 2-‐dimensional map has become key to many kinds of spatial representation, showing how this software has moved from the desktop to the web as well as how 2-‐d has moved to 3-‐d in terms of the visualisation of maps. Second, we explore how social data is being augmented by space-‐time series generated in real time and show how such real-‐time streaming of data presents problems and opportunities in which visualisation is key. We illustrate these new data for basic feeds from cities but then move to examine data from transit systems, social media, and data that is pulled from the crowd – crowdsourcing. Finally we note the development of visual analytics showing how 2d and 3d spatial representations are essential to interpreting the outputs and the workings of more complex models and simulations. We conclude with the notion that much of what we develop in this chapter for the space-time domain is generic to the future representation of all kinds of social data
Services just for men? Insights from a national study of the well men services pilots.
Men continue to have a lower life expectancy in most countries compared to women. Explanations of this gendered health inequality tend to focus on male risk taking, unhealthy lifestyle choices and resistance to seeking help from health services. In the period 2005-2008 the Scottish Government funded a nationwide community health promotion programme aimed at improving men's health, called Well Men Service Pilots (henceforth WMS)
Biomarkers in dementia: clinical utility and new directions.
Imaging, cerebrospinal fluid (CSF) and blood-based biomarkers have the potential to improve the accuracy by which specific causes of dementia can be diagnosed in vivo, provide insights into the underlying pathophysiology, and may be used as inclusion criteria and outcome measures for clinical trials. While a number of imaging and CSF biomarkers are currently used for each of these purposes, this is an evolving field, with numerous potential biomarkers in varying stages of research and development. We review the currently available biomarkers for the three most common forms of neurodegenerative dementia, and give an overview of research techniques that may in due course make their way into the clinic
Hospitalization for pertussis: profiles and case costs by age
BACKGROUND: Pertussis, a highly contagious respiratory illness, affects people of all ages and can have serious clinical consequences. It has been reported that from 1997–2000, 20% of all pertussis cases required hospitalization in the US. This analysis examined demographics, case fatality rate, resource use and costs of hospital care related to pertussis by age. METHODS: ICD-9 codes (033.0, 033.9) were used to identify cases of pertussis in hospital discharge databases from roughly 1,000 US hospitals in 4 states (California, Florida, Maryland, Massachusetts). Data from 1996–1999 were examined by age group. Separate analyses were done for infants (<1 year) and children (1–11 years); however, adolescent and adult cases were combined into one group (12+ years), due to the small number of cases. Databases were used to determine demographics, health service utilization and care costs. Cost estimates include accommodations, ancillary and physician services, reported in 2002 US9,586 per stay. Children (n = 191) had a mean LOS of 3.7 and cost of 5,683 per hospitalization. CONCLUSION: Infants are responsible for the bulk of hospitalizations and generate higher inpatient costs. Costly hospital care occurs, however, in patients with pertussis at all ages
An asymmetric shock wave in the 2006 outburst of the recurrent nova RS Ophiuchi
Nova outbursts take place in binary star systems comprising a white dwarf and
either a low-mass Sun-like star or, as in the case of the recurrent nova RS
Ophiuchi, a red giant. Although the cause of these outbursts is known to be
thermonuclear explosion of matter transferred from the companion onto the
surface of the white dwarf, models of the previous (1985) outburst of RS
Ophiuchi failed to adequately fit the X-ray evolution and there was controversy
over a single-epoch high-resolution radio image, which suggested that the
remnant was bipolar rather than spherical as modelled. Here we report the
detection of spatially resolved structure in RS Ophiuchi from two weeks after
its 12 February 2006 outburst. We track an expanding shock wave as it sweeps
through the red giant wind, producing a remnant similar to that of a type II
supernova but evolving over months rather than millennia. As in supernova
remnants, the radio emission is non-thermal (synchrotron emission), but
asymmetries and multiple emission components clearly demonstrate that contrary
to the assumptions of spherical symmetry in models of the 1985 explosion, the
ejection is jet-like, collimated by the central binary whose orientation on the
sky can be determined from these observations.Comment: 10 pages, 4 figures, accepted by Natur
Capturing the essence of folding and functions of biomolecules using Coarse-Grained Models
The distances over which biological molecules and their complexes can
function range from a few nanometres, in the case of folded structures, to
millimetres, for example during chromosome organization. Describing phenomena
that cover such diverse length, and also time scales, requires models that
capture the underlying physics for the particular length scale of interest.
Theoretical ideas, in particular, concepts from polymer physics, have guided
the development of coarse-grained models to study folding of DNA, RNA, and
proteins. More recently, such models and their variants have been applied to
the functions of biological nanomachines. Simulations using coarse-grained
models are now poised to address a wide range of problems in biology.Comment: 37 pages, 8 figure
Be careful with triage in emergency departments: interobserver agreement on 1,578 patients in France
<p>Abstract</p> <p>Background</p> <p>For several decades, emergency departments (EDs) utilization has increased, inducing ED overcrowding in many countries. This phenomenon is related partly to an excessive number of nonurgent patients. To resolve ED overcrowding and to decrease nonurgent visits, the most common solution has been to triage the ED patients to identify potentially nonurgent patients, i.e. which could have been dealt with by general practitioner. The objective of this study was to measure agreement among ED health professionals on the urgency of an ED visit, and to determine if the level of agreement is consistent among different sub-groups based on following explicit criteria: age, medical status, type of referral to the ED, investigations performed in the ED, and the discharge from the ED.</p> <p>Methods</p> <p>We conducted a multicentric cross-sectional study to compare agreement between nurses and physicians on categorization of ED visits into urgent or nonurgent. Subgroups stratified by criteria characterizing the ED visit were analyzed in relation to the outcome of the visit.</p> <p>Results</p> <p>Of 1,928 ED patients, 350 were excluded because data were lacking. The overall nurse-physician agreement on categorization was moderate (kappa = 0.43). The levels of agreement within all subgroups were variable and low. The highest agreement concerned three subgroups of complaints: cranial injury (kappa = 0.61), gynaecological (kappa = 0.66) and toxicology complaints (kappa = 1.00). The lowest agreement concerned two subgroups: urinary-nephrology (kappa = 0.09) and hospitalization (kappa = 0.20). When categorization of ED visits into urgent or nonurgent cases was compared to hospitalization, ED physicians had higher sensitivity and specificity than nurses (respectively 94.9% versus 89.5%, and 43.1% versus 30.9%).</p> <p>Conclusions</p> <p>The lack of physician-nurse agreement and the inability to predict hospitalization have important implications for patient safety. When urgency screening is used to determine treatment priority, disagreement might not matter because all patients in the ED are seen and treated. But using assessments as the basis for refusal of care to potential nonurgent patients raises legal, ethical, and safety issues. Managed care organizations should be cautious when applying such criteria to restrict access to EDs.</p
A new hammer to crack an old nut : interspecific competitive resource capture by plants is regulated by nutrient supply, not climate
Peer reviewedPublisher PD
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