1,921 research outputs found
A hybrid metal/semiconductor electron pump for quantum metrology
Electron pumps capable of delivering a current higher than 100pA with
sufficient accuracy are likely to become the direct mise en pratique of the
possible new quantum definition of the ampere. Furthermore, they are essential
for closing the quantum metrological triangle experiment which tests for
possible corrections to the quantum relations linking e and h, the electron
charge and the Planck constant, to voltage, resistance and current. We present
here single-island hybrid metal/semiconductor transistor pumps which combine
the simplicity and efficiency of Coulomb blockade in metals with the
unsurpassed performances of silicon switches. Robust and simple pumping at
650MHz and 0.5K is demonstrated. The pumped current obtained over a voltage
bias range of 1.4mV corresponds to a relative deviation of 5e-4 from the
calculated value, well within the 1.5e-3 uncertainty of the measurement setup.
Multi-charge pumping can be performed. The simple design fully integrated in an
industrial CMOS process makes it an ideal candidate for national measurement
institutes to realize and share a future quantum ampere
Aquariums as Reservoirs for Multidrug-resistant Salmonella Paratyphi B
Multidrug-resistant Salmonella enterica serovar Paratyphi B dT+ isolates from patients with gastroenteritis were identical with isolates from their home aquariums. Matched isolates had identical phage types, XbaI and IS200 profiles, and Salmonella genomic island 1 (SGI1). Ornamental fish tanks are reservoirs for SGI1-containing S. Paratyphi B dT+
Hydrodynamic Effects of Debris Blockage and Scour on Masonry Bridges: Towards Experimental Modelling
This is the author accepted manuscript. The final version is available from CRC Press via the DOI in this record8th International Conference on Scour and Erosion, 12-15 September 2016, Oxford, UKThis paper describes the preliminary stage of an ongoing project investigating the hydrodynamic effects of debris blockage at masonry bridges. Debris blockage is cited as one of the primary causes of bridge failures in the UK and around the world. Masonry bridges, many of which are valuable historical assets, are particularly vulnerable to debris blockage due to their short spans and low clearance. This paper presents work done as part of the first phase of the project involving experimental research to understand the scientific relationships between debris characteristics and flow conditions. The study, being carried out at Centre for Water Systems at University of Exeter, utilizes a 0.6m-wide and 10m-long flume to run hydraulic experiments in order to characterize the impact of debris blockage on flow hydrodynamics, scour, and hydrodynamic pressures and forces at masonry bridges. This paper outlines the design of the experimental setup and the reasoning behind the choices for preliminary experimental parameters. The experiments are to include testing of bridge models and various 3D-printed debris shapes under realistic flow conditions. Geometry of the bridge and debris mod-els are kept approximately similar to prototype conditions, with hydraulic conditions of the experiments de-signed to the degree that experimental constraints allow based on Froude similarity. Velocities, scour and hy-drodynamic pressures are measured using an Acoustic Doppler Velocimeter, echo-sounding concept and pres-sure sensors, respectively. Preliminary results indicate that the designed experiments have the potential to en-hance our understanding of the hydrodynamic effects of debris blockage.The research presented in this paper was supported by funding from the UK’s Engineering and Physical Sciences Research Council (EPSRC) under grant EP/M017354/1. The authors are grateful to project partners for their support, particularly Devon County Council and Network Rail for providing useful prototype data
Prediction of flow around a sharp-nosed bridge pier: Influence of the Froude number and free surface variation on the flow field (article)
This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThe dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.1503Author accepted manuscript replaced with published version by Caroline Huxtable on 2019-10-11This study investigates the influence of free surface variation on the velocity field using numerical simulations of flow around a
sharp-nosed pier that is representative of a typical masonry bridge pier. This study evaluates the assumption that free surface effects
are negligible at small Froude numbers by comparing the change in flow field predictions due to the use of a free surface model (i.e.
multi-phase simulation with a Volume of Fluid (VOF) model in place of a rigid-lid approximation (i.e. single phase simulation).
Results show that simulations using the VOF model are in better agreement with experimental data than those using the rigid-lid
approximation. Importantly, results show that even though the change in free surface height near the pier is small comparative to
the approach flow, it still has a significant effect on velocities in front of the pier and in the wake region, and that too at low Froude
numbers.Engineering and Physical Sciences Research Council (EPSRC
Scour and hydrodynamic effects of debris blockage at masonry bridges: insights from experimental and numerical modelling
The final version is available from IAHR via the URL in this record.This paper describes preliminary results of a project investigating the scour and hydrodynamic effects of debris blockage at masonry bridges. Debris blockage, which is often cited as one of the primary causes of bridge failures in the UK and around the world, results in a larger obstruction to the flow leading to increased flow velocities, scour and hydrodynamic forces, compared to the conditions without debris. This, in turn, can affect the structural stability of bridges, for example, by undermining their foundations. Masonry bridges, many of which are valuable historical assets, are particularly vulnerable to debris blockage due to their short spans and low clearance. The reported study, being undertaken at the Centre for Water Systems at the University of Exeter, has two main phases: (i) laboratory experiments and (ii) CFD simulations. In the first phase, a 0.6m-wide and 10m-long flume is utilized to study the flow hydrodynamics and scour associated with pier/bridge models in several reference scenarios. The geometry of the pier/bridge and debris models are kept approximately similar to prototype conditions, with hydraulic conditions of the experiments designed to the degree that laboratory constraints allow to maintain Froude similarity. Velocities and scour are measured via an acoustic Doppler velocimeter and echo-sounding concept. Experimental results are used to calibrate and validate CFD models which can later enable simulation of more complicated scenarios. This paper will report these preliminary results from both experimental and CFD phases. Preliminary experimental results highlight the significance of debris existence in enhancing scour due to increasing flow downward velocities. Preliminary results from CFD modelling also show good agreement with experimental results.The research presented in this paper was supported by funding from the UK’s Engineering and Physical
Sciences Research Council (EPSRC) under grant EP/M017354/1
Rapid identification of some Leptospira isolates from cattle by random amplified polymorphic DNA fingerprinting
We compared random amplified polymorphic DNA (RAPD) fingerprinting with cross-absorption agglutination and restriction enzyme analysis for typing bovine leptospires. Using RAPD fingerprinting, we examined a number of Leptospira serovars, namely, hardjo genotypes bovis and prajitno, pomona, balcanica, tarassovi, swajizak, kremastos, australis, and zanoni, which are likely to be isolated from Australian cattle. Each serovar and genotype had a unique RAPD profile. Of 26 field isolates of Leptospira, 23 were identified as hardjo genotype bovis subtype A, 2 were identified as zanoni, and 1 was identified as pomona by RAPD fingerprinting, and their types were confirmed by cross-absorption agglutination and restriction enzyme analysis
Reconstructive Procedures after Total Gastrectomy for Gastric Cancer
Till this day, there are more than 60 described surgical procedures of the intestinal reconstructions after a total gastrectomy. In 1897, Schlatter reconstructed the digestive tract by creating a termino-lateral esophagojejunostomies that was the first successful total gastrectomy. Many of the total gastrectomy pioneers did the reconstruction by esophagoduodenostomy or by forming a loop esophagojejunostomy. The main reconstruction modalities after a total gastrectomy are a restitution of the intestinal continuity, without a preservation of the duodenal food passage (esophagojejunostomy with a Roux-en-Y configuration) and a restitution of the intestinal continuity with a preservation of the duodenal passage (esophagojejunostomy with Roux-en-Y configuration and forming of the lateral-terminal jejunoduodenal anastomosis double tract and jejunal interposition by Longmire). The surgeries in these categories can be combined with forming of an enteral pouch or a stomach reservoir which would simulate a reservoir of a normal intact stomach. The ideal reconstruction procedure after total gastrectomy should replace all lost functions of the stomach. Preservation of duodenal transit with replacement of the jejunal segment, the so-called physiological route, is now believed to be preferential for postoperative nutritional condition, prevents persistent postgastrectomy syndrome, and improves the quality of life. Reconstructive procedures which allow duodenal passage should be regarded as a key to physiological reconstruction
Dietary fat intake as a risk factor for the development of diabetes. Multinational, multicenter study of the Mediterranean Group for the Study of Diabetes (MGDS)
In the context of the Multinational MGSD Nutrition Study, three groups of subjects were studied: 204 subjects with recently diagnosed diabetes(RDM),42subjectswithundiagnoseddiabetes(UDM)(AmericanDiabetesAssociation criteria—fasting plasma glucose [FPG] 126 mg/dl), and 55 subjects with impaired fasting glucose(IFG)(FPG 110and126mg/dl).Eachgroupwascomparedwithacontrolgroupof nondiabetic subjects, matched one by one for center, sex, age, and BMI. Nutritional habits were evaluated by a dietary history method, validated against the 3-day diet diary. In RDM, the questionnaire referred to the nutritional habits before the diagnosis of diabetes. Demographic data were collected, and anthropometrical and biochemical measurements were taken. RESULTS— Compared with control subjects, RDM more frequently had a family history of diabetes(49.0vs.14.2%;P0.001),exercisedless(exerciseindex53.5vs.64.4;P0.01),and more frequently had sedentary professions (47.5 vs. 27.4%; P 0.001). Carbohydrates contributed less to their energy intake (53.5 vs. 55.1%; P 0.05), whereas total fat (30.2 0.5 vs. 27.8 0.5%; P 0.001) and animal fat (12.2 0.3 vs. 10.8 0.3%; P 0.01) contributed moreandtheplant-to-animalfatratiowaslower(1.50.1vs.1.80.1;P0.01).UDMmore frequentlyhadafamilyhistoryofdiabetes(38.1vs.19.0%;P0.05)andsedentaryprofessions (58.5vs.34.1%;P0.05),carbohydratescontributedlesstotheirenergyintake(47.61.7vs. 52.81.4%;P0.05),totalfat(34.71.5vs.30.41.2%;P0.05)andanimalfat(14.2 0.9 vs. 10.6 0.7%; P 0.05) contributed more, and the plant-to-animal fat ratio was lower (1.6 0.2 vs. 2.3 0.4; P 0.05). IFG differed only in the prevalence of family history of diabetes (32.7 vs. 16.4%; P 0.05). CONCLUSIONS— Our data support the view that increased animal fat intake is associated with the presence of diabetes
A practical method to assess risks from large wood debris accumulations at bridge piers
This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this recordAccumulations of large woody debris can worsen scour at a bridge pier
and thereby lead to structural damage. Accumulations can also increase the
flood risk in adjacent areas. These consequences can cause disruption to
local communities and even pose a risk to human life. Current methodologies acknowledge the existence of these effects of debris but do not provide a
practical method, usable by engineers and practitioners, to assess the potential for debris accumulation at a bridge structure based on readily available
data. This work aims to address this practical need by proposing a methodology based on direct and indirect observations. Using this methodology, a
desk-based analysis can be performed to assess whether a bridge is prone to
the formation of debris accumulations. Direct observations may include information from inspection reports, satellite imagery and tree removal works,
while indirect observations may use information related to the geographical
location of the bridge such as on other structures that share the watercourse
or the presence of forested areas in its proximity. This methodology has been
applied to local authority-owned bridges in Devon, UK. Results show that
a large number of the structures (100 out of over 3000 bridges) are liable
to debris accumulations. Direct observations served as primary evidence for
over 80% of the bridges liable to debris accumulations. For many cases,
direct observations existed to corroborate indirect observations suggesting
that indirect observations can also be relied upon. The proposed methodology has also been applied to the prioritisation of bridge inspections for
scour assessment. Results showed that many of the bridges prone to debris
accumulations would need to be prioritised for scour inspections over other
bridges in the aftermath of floods due to their significantly higher risk to scour in the presence of debris.Engineering and Physical Sciences Research Council (EPSRC
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