7,171 research outputs found
Systematic review of antimicrobial drug prescribing in hospitals.
Prudent antibiotic prescribing to hospital inpatients has the potential to reduce the incidences of antimicrobial resistance and healthcare-associated infection. We reviewed the literature from January 1980 to November 2003 to identify rigorous evaluations of interventions to improve hospital antibiotic prescribing. We identified 66 studies with interpretable data of which 16 reported 20 microbiological outcomes: Gram negative resistant bacteria (GNRB), 10 studies; Clostridium difficile associated diarrhoea (CDAD), 5 studies; vancomycin resistant enterococci (VRE), 3 studies and methicillin resistant Staphylococcus aureus (MRSA), 2 studies. Four studies provide good evidence that the intervention changed microbial outcomes with low risk of alternative explanations, eight studies provide less convincing evidence and four studies were negative. The strongest and most consistent evidence was for CDAD but we were able to analyse only the immediate impact of interventions because of nonstandardised durations of follow up. The ability to compare results of studies could be substantially improved by standardising methodology and reporting
Effects of diamagnetic levitation on bacterial growth in liquid
Diamagnetic levitation is a technique that uses a strong, spatially-varying magnetic field to levitate diamagnetic materials, such as water and biological cells. This technique has the potential to simulate aspects of weightlessness, on the Earth. In common with all ground-based techniques to simulate weightlessness, however, there are effects introduced by diamagnetic levitation that are not present in space. Since there have been few studies that systematically investigate these differences, diamagnetic levitation is not yet being fully exploited. For the first time, we critically assess the effect of diamagnetic levitation on a bacterial culture in liquid. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 hours, in a series of experiments to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture. The speed of sedimentation of the bacterial cells to the bottom of the container is considerably reduced. Further experiments and microarray gene analysis show that the growth enhancement is due to greater oxygen availability in the magnetically levitated sample. We demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid, an effect not present in microgravity. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause the liquid to become unstable to convection when the consumption of oxygen by the bacteria generates an oxygen concentration gradient. We propose that this convection enhances oxygen availability by transporting oxygen around the sample. Since convection is absent in space, these results are of significant importance and timeliness to researchers considering using diamagnetic levitation to explore weightless effects on living organisms and a broad range of other topics in the physical and life sciences
An economic survey of New Zealand town milk producers 1976-77
This report is the fourth in an annual series
of economic surveys of New Zealand town milk supply
farms. These surveys have been undertaken by the
Agricultural Economics Research Unit at Lincoln College
on behalf of the New Zealand Milk Board and the Town
Milk Producers Federation of New Zealand (Inc.)
As in the past the major objective of this survey
has been to estimate the average net farm income
received by town milk producers in New Zealand. In
addition, however, the opportunity provided by the surveys
has been used to collect additional data so that a
more comprehensive profile of the industry emerges
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Dynamic Load and Storage Integration
Modern technology combined with the desire to minimize the size and weight of a ship’s power system are leading to renewed interest in more electric or all electric ships. An important characteristic of the emerging ship power system is an increasing level of load variability, with some future pulsed loads requiring peak power in excess of the available steady– state power. This inevitably leads to the need for some additional energy storage beyond that inherent in the fuel. With the current and evolving technology, it appears that storage will be in the form of batteries, rotating machines, and capacitors. All of these are in use on ships today and all have enjoyed significant technological improvements over the last decade. Moreover all are expected to be further enhanced by today’s materials research. A key benefit of storage is that, when it can be justified for a given load, it can have additional beneficial uses such as ride-through capability to restart a gas turbine if there is an unanticipated power loss; alternatively, storage can be used to stabilize the power grid when switching large loads. Knowing when to stage gas turbine utilization versus energy storage is a key subject in this paper. The clear need for storage has raised the opportunity to design a comprehensive storage system, sometimes called an energy magazine, that can combine intermittent generation as well as any or all of the other storage technologies to provide a smaller, lighter and better performing system than would individual storage solutions for each potential application.Center for Electromechanic
Rossby adjustment over a step
The adjustment of a rotating fluid to a geostrophic equilibrium is now a classical problem in the theory of rotating fluids and is associated with the name of Rossby because of his pioneering work in this subject. The case of particular interest here is the one where the fluid is initially at rest but has a discontinuity in surface elevation along a certain line. If the bottom is flat, the adjustment gives rise to a jet flowing along the line of the initial discontinuity, the width of the jet being the Rossby radius of deformation. This paper examines how the flow is modified when the bottom is not flat, but has a step-like discontinuity running perpendicular to the line of the initial jump in surface elevation, giving rise to double Kelvin waves which propagate along the step. Flow is thus diverted parallel to the step, and behind the wave front there is no mass flux across the step.The effect of adding a vertical coast perpendicular to the step is also considered. When the double Kelvin wave propagates offshore, it leaves behind a state with no transport across the step. With propagation toward the coast, however, there is pinching of the longshore current into a narrow boundary layer.The problem is examined using (a) linear analysis, (b) laboratory experiments, and (c) numerical experiments
An economic survey of New Zealand wheatgrowers : survey no. 2
This is survey number 2. No. 1 was know as "National wheatgrowers' survey"This Report is the second in an annual series of economic
surveys of New Zealand wheatgrowing farms. These surveys have been undertaken by the Agricultural Economics Research Unit
at Lincoln College on behalf of Wheat Growers Sub-Section of
Federated Farmers of New Zealand Inc.
Specific attention has been focused on the physical
characteristics of wheatgrowing farms, the area of wheat and
other crops sown, wheat yields, cultural practices and costs and
returns for the 1977/78 wheat crop. An attempt has also been
made to allocate plant and machinery overhead costs to the wheat
enterprise on both an historical and current cost basis.
The need for current and detailed information from the
Survey involved two visits to the farms in the sample; one in
the spring following drilling and the second in the autumn after
harvest
On a discrete Davey-Stewartson system
We propose a differential difference equation in and study it by
Hirota's bilinear method. This equation has a singular continuum limit into a
system which admits the reduction to the Davey-Stewartson equation. The
solutions of this discrete DS system are characterized by Casorati and Grammian
determinants. Based on the bilinear form of this discrete DS system, we
construct the bilinear B\"{a}cklund transformation which enables us to obtain
its Lax pair.Comment: 12 pages, 2 figure
Spectral decomposition for the Dirac system associated to the DSII equation
A new (scalar) spectral decomposition is found for the Dirac system in two
dimensions associated to the focusing Davey--Stewartson II (DSII) equation.
Discrete spectrum in the spectral problem corresponds to eigenvalues embedded
into a two-dimensional essential spectrum. We show that these embedded
eigenvalues are structurally unstable under small variations of the initial
data. This instability leads to the decay of localized initial data into
continuous wave packets prescribed by the nonlinear dynamics of the DSII
equation
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