To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
This paper describes a simulation technique that has been developed to quantify the unsteady forces and moments that are imposed onto a maritime helicopter by a ship’s airwake during a deck landing. An unsteady CFD-generated airwake, created using a CAD model of the ship, is integrated with a flight dynamics model of a helicopter. By holding the helicopter at a fixed position in the airwake it is possible to quantify the unsteady forces and moments imposed on the aircraft. The technique is therefore a software-based airwake dynamometer, and has been called the virtual AirDyn. As well as determining the mean loads, from consideration of the unsteady loads in the closed-loop pilot response frequency range of 0·2-2Hz it is also possible to quantify the magnitude of the unsteady disturbance in each axis. The loads are also indicators of the control activity the pilot would have to exert to maintain aircraft position and attitude. By placing the virtual AirDyn at different positions around the landing deck in different wind conditions, it is able to quantify the effect of the airwake on the mean and unsteady loads. The quantified loads can be explained by examining the CFD-generated flow field, and the geometric features on the ship’s superstructure that gave rise to them can be identified. The virtual AirDyn is therefore a tool that can be used to evaluate and inform ship design for maritime helicopter operations.
Contact precautions are a cornerstone of infection prevention but have also been associated with less healthcare worker (HCW) contact and adverse events. We studied how contact precautions modified HCW behavior in 4 acute care facilities.
Prospective cohort study.
Participants and Setting.
Four acute care facilities in the United States performing active surveillance for methicillin-resistant Staphylococcus aureus.
Trained observers performed “secret shopper” monitoring of HCW activities during routine care, using a standardized collection tool and fixed 1-hour observation periods.
A total of 7,743 HCW visits were observed over 1,989 hours. Patients on contact precautions had 36.4% fewer hourly HCW visits than patients not on contact precautions (2.78 vs 4.37 visits per hour; P< .001 ) as well as 17.7% less direct patient contact time with HCWs (13.98 vs 16.98 minutes per hour; P = .02). Patients on contact precautions tended to have fewer visitors (23.6% fewer; P = .08). HCWs were more likely to perform hand hygiene on exiting the room of a patient on contact precautions (63.2% vs 47.4% in rooms of patients not on contact precautions; P< .001).
Contact precautions were found to be associated with activities likely to reduce transmission of resistant pathogens, such as fewer visits and better hand hygiene at exit, while exposing patients on contact precautions to less HCW contact, less visitor contact, and potentially other unintended outcomes.
This paper presents highlights from research conducted at the University of Liverpool to determine suitable fidelity criteria and guidelines for the modelling and simulation of the helicopter-ship dynamic interface environment. The paper begins by describing the characteristics of the helicopter-ship dynamic interface, explaining the motivation behind the research and reviewing the state-of-the-art in dynamic interface simulation. The development of a dynamic interface research environment based on an existing research simulator operated by the University of Liverpool is then described, before key results from a number of piloted simulation experiments are presented. These experiments were specifically designed to address fidelity sensitivity issues, such as, are unsteady airwake models necessary, or can a steady airwake model induce appropriate levels of pilot workload? What influence does the modelled ship geometry, or choice of atmospheric wind conditions have on the airwake model and on pilot workload? Finally, the paper concludes by briefly describing the relevance of these research findings to current and future industry programmes.
Prisoners with mental illness on release from prison often face complex challenges with little support, leading to poor clinical and social outcomes. This feasibility study aimed to see whether a Critical Time Intervention (CTI) in the first weeks post-release effectively connects mentally ill prisoners with social, clinical, housing, and welfare services on leaving prison. The study took place in 2007 and involved local prisons in London and Manchester.
A pilot randomised controlled trial in which CTI was compared to Treatment as Usual (TAU).
Sixty prisoners were randomised in the trial, with outcome measures completed on 23. A higher proportion of prisoners in CTI group were in contact with services at follow-up than those receiving TAU. CTI prisoners were significantly more likely to be receiving medication, and be registered with a General Practitioner (GP) than those in the TAU group.
Continuity of care for prisoners with severe mental illness can be improved by working with them to identify their needs prior to release, and by assisting them to engage effectively to the necessary agencies in the community.
The administration per-orally to mice of the non-absorbable antibiotics polymyxin E, tobramycin and amphotericin B resulted in the elimination of detectable aerobic gram-negative rods from the faecal flora without affecting the total viable aerobic count. The addition of parental cefotaxime to the regime caused a fall in the number of aerobic lactobacilli and an increase in the number of enterococci. The rise was associated with the translocation of viable enterococci to the mesenteric lymph nodes and the spleen. The changes induced by cefotaxime were reversed when the antibiotic was withdrawn. Following withdrawal of all antibiotics the total aerobic faecal flora increased to above normal levels, but there was no associated diarrhoea. Attempts to implant exogenous enterobacteria into the digestive tract resulted in only low level colonization both in treated mice and in control mice. These results may have implications for the use of this antibiotic regime for selective decontamination of the digestive tract in humans, particularly those who are immunocompromised.
To determine the relationship of diet to overweight and obesity among populations of African origin.
Design and setting
Cross-sectional data were obtained from adults aged 25–74 years in rural Cameroon (n = 686), urban Cameroon (n = 975), Jamaica (n = 924) and Afro-Caribbeans in the UK (n = 257). Dietary data were collected using food-frequency questionnaires specifically designed for each site. Body mass index (BMI) was used as a measure of overweight.
The expected gradient in the distribution of overweight across sites was seen in females (rural Cameroon, 9.5%; urban Cameroon, 47.1%; Jamaica, 63.8%; UK, 71.6%); however, among males overweight was less prevalent in Jamaica (22.0%) than urban Cameroon (36.3%). In developing countries increased risks of overweight (BMI ≥ 25 kg m− 2) were influenced by higher energy (urban Cameroonian men) and protein (Jamaican women) intakes. No dietary variables were associated with obesity (BMI ≥ 30 kg m− 2) in Cameroon or Jamaica. In the UK, energy intakes were inversely related with overweight whereas increased risks of being overweight were associated with higher protein (men) and fat (women) intakes. Similarly, whereas higher protein and fat intakes in UK men and women were associated with obesity, carbohydrate intakes were associated with decreased risks of obesity in men.
Diet and overweight were associated in the UK but few dietary variables were related to overweight in Jamaica and the Cameroon. These findings suggest that associations between diet and overweight/obesity are not generalisable among populations.
Rabbit haemorrhagic disease virus (RHDV) has killed many millions of wild rabbits in Europe and Australia, but has had little impact in the United Kingdom, despite outbreaks having occurred since 1994. High seroprevalence detected in the absence of associated mortality had suggested the presence of an endemic non-pathogenic strain which may be ‘protecting’ UK populations. Following the first detailed field study of RHDV epidemiology in the United Kingdom, using mark–recapture with serum sampling, we report that RHDV caused highly prevalent persistent infection in seropositive rabbits in the absence of associated mortality. Furthermore the virus strains responsible could not be distinguished phylogenetically from known pathogenic isolates, and were clearly very different from the only previously identified non-pathogenic strain of RHDV. These findings suggest that many – perhaps most – strains of RHDV may be propagated through both ‘pathogenic’ and ‘non-pathogenic’ modes of behaviour. Transmission occurred predominantly during and just after the breeding season.
Okamoto has obtained a sequence of τ-functions for the PVI system expressed as a double Wronskian determinant based on a solution of the Gauss hypergeometric equation. Starting with integral solutions of the Gauss hypergeometric equation, we show that the determinant can be re-expressed as multidimensional integrals, and these in turn can be identified with averages over the eigenvalue probability density function for the Jacobi unitary ensemble (JUE), and the Cauchy unitary ensemble (CyUE) (the latter being equivalent to the circular Jacobi unitary ensemble (cJUE)). Hence these averages, which depend on four continuous parameters and the discrete parameter N, can be characterised as the solution of the second order second degree equation satisfied by the Hamiltonian in the PVI theory. We show that the Hamiltonian also satisfies an equation related to the discrete PV equation, thus providing an alternative characterisation in terms of a difference equation. In the case of the cJUE, the spectrum singularity scaled limit is considered, and the evaluation of a certain four parameter average is given in terms of the general PV transcendent in σ form. Applications are given to the evaluation of the spacing distribution for the circular unitary ensemble (CUE) and its scaled counterpart, giving formulas more succinct than those known previously; to expressions for the hard edge gap probability in the scaled Laguerre orthogonal ensemble (LOE) (parameter a a non-negative integer) and Laguerre symplectic ensemble (LSE) (parameter a an even non-negative integer) as finite dimensional combinatorial integrals over the symplectic and orthogonal groups respectively; to the evaluation of the cumulative distribution function for the last passage time in certain models of directed percolation; to the τ-function evaluation of the largest eigenvalue in the finite LOE and LSE with parameter a = 0; and to the characterisation of the diagonal-diagonal spin-spin correlation in the two-dimensional Ising model.
Escherichia coli O157 infections cause an estimated 60 deaths and 73000 illnesses annually in the United States. A marked summer peak in incidence is largely unexplained. We investigated an outbreak of E. coli O157 infections at an agricultural fair in Ohio and implicated consumption of beverages made with fairground water and sold by a geographically localized group of vendors who were all on the same branch of the fairground water distribution system. To examine county fair attendance as a risk factor for infection, we conducted two further epidemiological studies. In the first, we enhanced surveillance for E. coli O157 infections in 15 Northeast Ohio counties during the 2000 agricultural fair season and showed increased risk of E. coli O157 infection among fair attendees. In the second study, we examined Ohio Public Health Laboratory Information Service (PHLIS) data for 1999 using a time-varying covariate proportional hazards model and demonstrated an association between agricultural fairs and E. coli O157 infections, by county. Agricultural fair attendance is a risk factor for E. coli O157 infection in the United States and may contribute to the summer peak in incidence. Measures are needed to reduce transmission of enteric pathogens at agricultural fairs.
The probability that an interval I is free of eigenvalues in a matrix ensemble with unitary symmetry is given by a Fredholm determinant. When the weight function in the matrix ensemble is a classical weight function, and the interval I includes an endpoint of the support, Tracy and Widom have given a formalism which gives coupled differential equations for the required probability and some auxiliary quantities. We summarize and extend earlier work by expressing the probability and some of the auxiliary quantities in terms of Painlevé transcendents.
In October 1997 the Times of London announced the sale by
auction of fourteen hundred gold coins that formed part of the hoard
lost by Clive of India when the East Indiaman Dodington was
wrecked in Algoa Bay on July 17, 1755. The wreck and its contents lie
within South African territorial waters and are protected by South
African heritage legislation. Very little gold has ever been reported
recovered, despite ongoing excavations, and only a single permit has
been issued for the export and sale of twenty–one gold coins. This article will consider the legal steps taken to repatriate the coins, and the difficulties encountered when taking such steps before a foreign court. It evaluates the extent to which existing international conventions, including the recently adopted UNESCO Convention on the Protection of Underwater Cultural Heritage, are able to assist states in repatriating stolen or illegally exported underwater cultural heritage.
An interviewer-administered quantitative food-frequency questionnaire (FFQ) was developed to determine the energy and nutrient intakes of adult Jamaicans of African origin as part of a study of the epidemiology of diabetes and hypertension.
Reproducibility of the questionnaire was investigated in 123 participants aged 25–74 years. The relative validity of the FFQ was assessed against twelve 24-hour recalls administered over 12 months in 73 of the participants. In addition, energy intakes (EI) were compared with estimated basal metabolic rates (BMR).
Reproducibility correlation coefficients (Pearson and intraclass) varied between 0.42 for retinol and 0.71 for carbohydrate, with most values falling between 0.50 and 0.60. When compared with repeated 24-hour recalls, the FFQ estimated slightly higher energy (mean 6%) and macronutrient intakes (mean 2–14%), and was within 5% when expressed as a percentage of energy intake. Micronutrients were higher by 1.19 (calcium) to 1.61 times (vitamin C). Unadjusted correlations between the FFQ and the reference method ranged from 0.20 for beta-carotene to 0.86 for alcohol. Cross-classification of nutrients into quartiles showed that 46–48% of participants in the lowest and highest quartiles were jointly classified by both methods. Misclassifications were low for most nutrients with one or two persons misclassified at the extreme quartiles. EI/BMR ratios suggested light to moderate activity levels appropriate for an urban population in a developing country.
The FFQ showed reasonable reproducibility and validity and is suitable for estimating the habitual intakes of energy and macronutrients, but was poor for some micronutrients (retinol and beta-carotene).
Background. Despite more than 100 years of study, there remains no definitive diagnostic
validation of the functional psychoses. Factor analysis suggests the presence of three or more
psychopathological syndromes in functional psychoses as a whole. The relationship between these
factors and cerebral anatomy has been investigated in schizophrenia only. This study aimed to
address the relationship of symptom factors to clinically important variables and cerebral anatomy
in a sample of psychotic patients with a spread of diagnoses.
Methods. In a sample of patients with functional psychoses, symptom data was obtained on four
consecutive admissions using the OPCRIT symptom checklist. OPCRIT data was used to generate
operational diagnoses in accordance with pre-set criteria and a principle components analysis was
performed on symptom data. Factor loadings were compared between each admission to examine
factor stability over time. Factor scores at first admission were also correlated with clinical variables
obtained from patients' case notes. From the sample of 204 patients, 64 subjects were recruited and
underwent an MRI scan of the brain. Regional anatomical volumes were compared with diagnosis
and factor loadings at first admission.
Results. A principal components analysis gave a four-factor solution of ‘manic’, ‘depressive’,
‘disorganization’ and ‘reality distortion’ factors at each admission. Factors showed a high degree
of stability over the four admissions studied. The factors were significantly associated with several
clinical variables. Three of the four factors were associated with a specific pattern of cerebral
Conclusions. This study suggests that factors may correspond to relatively specific disease processes
underlying functional psychotic illness. We propose that the use of symptom factors may facilitate
the investigation of the underlying mechanisms of psychotic illness.
This paper presents an x-ray diffraction and transmission electron microscopy analysis of Al1−xInxAs grown by molecular beam epitaxy. Two samples grown on (001) InP at temperatures of 370 and 400 °C are characterized. The first, which contains a high density of twin lamellae, exhibits triple-period short-range ordering with a rather short correlation range normal to the (111) planes. Within these (individual) planes, the concentration, however, is uniform over a considerably greater distance, leading to a highly anisotropic scattering. This is the first observation of triple-period short-range ordering in a sample that exhibits 2 × 1 surface reconstruction. The second sample exhibits CuPt-type short-range ordering with scattering that is significantly streaked, suggestive of lamellar-shaped ordered domains. Both samples contain high densities of stacking faults leading to additional sharp streaking along symmetry-allowed 〈111〉 directions.
Spatial studies of the emission line regions in planetary nebulae (PN) can provide insight into the physical and chemical environments across the nebulae. In a collaborative effort by the coauthors, a K-band Fabry-Perot etalon has been coupled with an advanced 256 × 256 InSb focal plane array at the Wyoming Infrared Observatory 2.3m telescope. This system permits us to obtain spatially resolved, 0.24″/pixel, moderate spectral resolution (R ≈ 800), flux-density IR emission line images of astronomical sources. We obtained continuum-subtracted images of Br γ, HeI 2.06 μm, the 2-μm UIR features, and the 3.3 μm PAH dust feature in the PN NGC 6572, NGC 7027, and NGC 7662. One objective was to determine the spatial morphology of two unidentified emission lines, UIR1−2.199 μm, and UIR2−2.287 μm (Geballe et al. 1991). These UIR lines appear in the spectra of many PN (Hora et al. 1997) and in the Orion Nebula (Luhman & Rieke 1996). Geballe et al. suggested that the UIR lines are most likely forbidden transitions and showed that the parent ion ionization potential is ≈ 30–40 eV, while the ionization potential for the ions themselves is 40–60 eV. Here we directly compare the distribution of the UIR emitters to that of the gas (H+,He+) and dust (PAHs).
We have studied the uniformity of the arsenic flux from a commercially available valved arsenic cracker source for MBE. There are many epitaxial structures that require a uniform arsenic flux distribution for rotated epitaxial growth and, in the non-rotated case, for RHEED. For non-stoichiometric GaAs growth at low substrate temperatures, which results in arsenic precipitates being formed during the in-situ anneal process, a specific As/Ga ratio must be used to maintain high crystalline quality and to achieve the desired electrical properties. Also, in the growth of InGaAsP the As/P ratio is equally important for lattice match and quality device results. We report on the uniformity of amorphous arsenic (a-As) films condensed on the surface of 3" diameter sapphire wafers slightly below room temperature. Sapphire substrates were used in place of GaAs wafers to facilitate the use of x-ray fluorescence for the measurement of the arsenic film uniformity. Uniformity maps will be presented for rotated and non-rotated a-As depositions of As2 and As4. Results indicate the uniformity of a-As, As4, films to have a standard deviation of < 2.5% across a 3" diameter substrate for the rotated case. Characteristics of the non-rotated case will be presented.
A transmission electron microscope investigation was made of zirconolites and perovskites irradiated to amorphization with 1 MeV krypton ions using the HVEM-Tandem Facility at Argonne National Laboratory. Three specimens were examined - a prototype zirconolite CaZrTi2O7, a gadolinium doped zirconolite Ca0.75Gd0.50Zr0.75Ti2O7and a uranium doped zirconolite Ca0.75U0.50Zr0.75Ti2O7. The critical amorphization dose Dc was determined at several temperatures between 20K to 675K. Dc was inversely proportional with temperature. For example, pure zirconolite requiring 10x the dose for amorphization at 475K compared with gadolinium zirconolite. Using an Arrhenius plot, the activation energy Ea for annealing in these compounds was found to be 0.129 eV and 0.067 eV respectively. The greater ease of amorphization for the gadolinium sample is probably a reflection of this element’s large cross section for interaction with heavy ions. Uranium zirconolite was very susceptible to damage and amorphised under 4 keV argon ions during the preparation of microscope specimens. In each sample, zirconolite coexisted with minor perovskite, reduced rutile (Magneli phases) and zirconia. These phases were more resistant to ion irradiation than zirconolite. Even for high gadolinium loadings, perovskite (Ca0.8Gd0.2TiO3) was 3-4 times more stable to ion irradiation than the surrounding zirconolite crystals.
We introduce a model to calculate the static equilibrium configuration between two monolayers of large, planar organic molecules bonded by van der Waals (vdW) forces. The Model significantly simplifies analysis by replacing the conventional atom-atom potential summation with a single ellipsoidal potential centered in the molecular plane. Our results indicate that recent observations of crystalline “quasi-epitaxial” growth of these planar molecular films in ultrahigh vacuum results from the relatively large intralayer elasticity as compared to the small interlayer stress. Good agreement between calculated and observed structures is achieved using no adjustable parameters. The Model is used to predict molecular structures which are likely to form quasi-epitaxial layers. Quasi-epitaxy is a general feature of large planar molecules of similar shape and size in adlayers and substrates where there is comparatively weak vdW bonding between layers.