An investigation into the structure of a turbulent plane jet.

PhDAn experimental investigation into the structure of the plane jet in a moving airstream has been made. The majority of the measurements have been made in a jet exhausting into a slow moving airstream providing an example of a possible self-preserving flow. The experiments showed that the flow does, in fact, become self-preserving at distances downstream from the jet nozzle of thirty jet nozzle width. The distributions of the turbulent intensities across the jet in the self-preserving region of the flow are shown to be similar to those found in the plane wake. However, the turbulent energy balance for the two flows appears to be quite different. Some measurements of the eddy structure indicate that shear carrying eddies are among the largest eddies in the flow and are also partly responsible for the intermittency phenomenon. The unsteady irrotational flow outside the jet is shown to be adequately described by the theories of Phillips (1955) and Stewart (1956). Some comments are made on the applicability of the various simple theories of turbulence to the plane jet and the interesting, though not necessarily significant, point emerges that the Prandtl Mixing Length theory gives the beat description of the flow structure. Additional measurements in jets in fast moving airstreams show that the change from a jet to a wake type of turbulence structure takes place at a very slow rate. Several simple theories were developed to account for the spread of a plane jet in a moving airstream but none of then proved wholly adequate. Apart from the main investigation, some work on the problem of measurements in a turbulent flow in discussed. Aspects of both hot wire anemometer theory and static pressure measurements are re-appraised

Developing digital interventions: a methodological guide.

Digital interventions are becoming an increasingly popular method of delivering healthcare as they enable and promote patient self-management. This paper provides a methodological guide to the processes involved in developing effective digital interventions, detailing how to plan and develop such interventions to avoid common pitfalls. It demonstrates the need for mixed qualitative and quantitative methods in order to develop digital interventions which are effective, feasible, and acceptable to users and stakeholders

A four year prospective study of age-related cognitive change in adults with Down's syndrome

Background. While neuropathological studies indicate a high risk for Alzheimer's disease in adults with Down's syndrome, neuropsychological studies suggest a lower prevalence of dementia. In this study, cognitive deterioration in adults with Down's syndrome was examined prospectively over 4 years to establish rates and profiles of cognitive deterioration.Methods. Fifty-seven people with Down's syndrome aged 30 years or older were assessed using a battery of neuropsychological tests on five occasions across 50 months. Assessments of domains of cognitive function known to change with the onset of Alzheimer related dementia were employed. These included tests of learning, memory, orientation, agnosia, apraxia and aphasia. The individual growth trajectory methodology was used to analyse change over time.Results. Severe cognitive deterioration, such as acquired, apraxia and agnosia, was evident in 28·3% of those aged over 30 and a higher prevalence of these impairments was associated with older age. The rate of cognitive deterioration also increased with age and degree of pre-existing cognitive impairment. Additionally, deterioration in memory, learning and orientation preceded the acquisition of aphasia, agnosia and apraxia.Conclusions. The prevalence of cognitive impairments consistent with the presence of Alzheimer's disease is lower than that suggested by neuropathological studies. The pattern of the acquisition of cognitive impairments in adults with Down's syndrome is similar to that seen in individuals with Alzheimer's disease who do not have Down's syndrome.</jats:p

Cuando la morfología y los marcadores moleculares entran en conflicto: el ejemplo de los anfípodos subterráneos de la región de Pilbara, Australia Occidental

Fifteen species of groundwater amphipods in the genus Chydaekata have been described from the Pilbara, Western Australia, each restricted to a single bore. Dewatering at a local mine site was halted while a second survey was undertaken. Newly collected samples were identified using the existing key, and allozyme analysis was used to test species boundaries. Allozymic diversity was not associated with single bores, and only two distinct genetic groups (one of which was very rare), were identified. Based on these results, and the finding that species were found to be more widespread, the Western Australian Environmental Protection Authority recommended that dewatering continue with caution at the site. This study provides an example of the problems associated with incongruent data sets, and the difficulties inherent in working with rare species, namely, interpreting the results of studies based on small samples or incomplete collections.Se han descrito quince especies de anfípodos de aguas subterráneas del género Chydaekata que habitan en la región de Pilbara, Australia Occidental, restringiéndose cada una de ellas a una única perforación. Mientras se elaboraba un segundo estudio, se interrumpió el desagüe que se estaba llevando a cabo en un emplazamiento minero local. Las nuevas muestras recolectadas se identificaron utilizando la clave existente, mientras que para verificar los límites de la especie se recurrió a un análisis alozimático. La diversidad alozimática no se asoció con perforaciones únicas y sólo se identificaron dos grupos genéticos bien diferenciados (uno de los cuales era muy poco común). Basándose en estos resultados y en el hallazgo de que la especie estaba más extendida, el Organismo de Protección Medioambiental de Australia Occidental recomendó que se actuara con cautela al proceder con el desagüe. El presente estudio brinda un ejemplo de los problemas asociados con conjuntos de datos incongruentes, así como las dificultades que conlleva trabajar con especies poco comunes, especialmente en lo que respecta a la interpretación de los resultados de estudios basados en pequeñas muestras o recolecciones incompletas

Echolocation detections and digital video surveys provide reliable estimates of the relative density of harbour porpoises

Acknowledgements We would like to thank Erik Rexstad and Rob Williams for useful reviews of this manuscript. The collection of visual and acoustic data was funded by the UK Department of Energy & Climate Change, the Scottish Government, Collaborative Offshore Wind Research into the Environment (COWRIE) and Oil & Gas UK. Digital aerial surveys were funded by Moray Offshore Renewables Ltd and additional funding for analysis of the combined datasets was provided by Marine Scotland. Collaboration between the University of Aberdeen and Marine Scotland was supported by MarCRF. We thank colleagues at the University of Aberdeen, Moray First Marine, NERI, Hi-Def Aerial Surveying Ltd and Ravenair for essential support in the field, particularly Tim Barton, Bill Ruck, Rasmus Nielson and Dave Rutter. Thanks also to Andy Webb, David Borchers, Len Thomas, Kelly McLeod, David L. Miller, Dinara Sadykova and Thomas Cornulier for advice on survey design and statistical approache. Data Accessibility Data are available from the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.cf04gPeer reviewedPublisher PD

Lithology and Internal Structure of the San Andreas Fault at Depth Based on Characterization of Phase 3 Whole-rock Core in the San Andreas Fault Observatory at Depth (SAFOD) Borehole

We characterize the lithology and structure of the spot core obtained in 2007 during Phase 3 drilling of the San Andreas Fault Observatory at Depth (SAFOD) in order to determine the composition, structure, and deformation processes of the fault zone at 3 km depth where creep and microseismicity occur. A total of approximately 41 m of spot core was taken from three separate sections of the borehole; the core samples consist of fractured arkosic sandstones and shale west of the SAF zone (Pacific Plate) and sheared fine-grained sedimentary rocks, ultrafine black fault-related rocks, and phyllosilicate-rich fault gouge within the fault zone (North American Plate). The fault zone at SAFOD consists of a broad zone of variably damaged rock containing localized zones of highly concentrated shear that often juxtapose distinct protoliths. Two zones of serpentinite-bearing clay gouge, each meters-thick, occur at the two locations of aseismic creep identified in the borehole on the basis of casing deformation. The gouge primarily is comprised of Mg-rich clays, serpentinite (lizardite ± chrysotile) with notable increases in magnetite, and Ni-Cr-oxides/hydroxides relative to the surrounding host rock. The rocks surrounding the two creeping gouge zones display a range of deformation including fractured protolith, block-in-matrix, and foliated cataclasite structure. The blocks and clasts predominately consist of sandstone and siltstone embedded in a clay-rich matrix that displays a penetrative scaly fabric. Mineral alteration, veins and fracture-surface coatings are present throughout the core, and reflect a long history of syn-deformation, fluid-rock reaction that contributes to the low-strength and creep in the meters-thick gouge zones

Observations of TeV gamma rays from Markarian 501 at large zenith angles

TeV gamma rays from the blazar Markarian 501 have been detected with the University of Durham Mark 6 atmospheric Cerenkov telescope using the imaging technique at large zenith angles. Observations were made at zenith angles in the range 70 - 73 deg during 1997 July and August when Markarian 501 was undergoing a prolonged and strong flare.Comment: 7 pages, 2 figures, accepted for publication in J. Phys. G.: Nucl. Part. Phy

Parsec Scale Properties of Markarian 501

We present the results of a high angular resolution study of the BL Lac object Markarian 501 in the radio band. We consider data taken at 14 different epochs, ranging between 1.6 GHz and 22 GHz in frequency, and including new Space VLBI observations obtained on 2001 March 5 and 6 at 1.6 and 5 GHz. We study the kinematics of the parsec-scale jet and estimate its bulk velocity and orientation with respect to the line of sight. Limb brightened structure in the jet is clearly visible in our data and we discuss its possible origin in terms of velocity gradients in the jet. Quasi-simultaneous multi-wavelength observations allow us to map the spectral index distribution and to compare it to the jet morphology. Finally, we estimate the physical parameters of the parsec-scale jet.Comment: accepted for publication in ApJ; 24 pages with 17 figures (fig. 1 and fig. 2 available only as .jpg files

Reallocation of Responsibilities and/or Financing for Selected Municipal Services to the State: A Municipal Finance Alternative

This report recommends that the administration and/or financing of a selected group of public services be shifted from municipalities to the state government in Massachusetts. Several criteria are used to identify local functions and local fiscal responsibilities which are more suitable for state than local financing. The first criterion is the efficiency of delivery of the service: for some functions, such as solid waste disposal, technology makes it more costly per capita to provide the service separately through individual municipalities than to operate regionally-based waste disposal facilities. The second criterion is the degree to which residents of the service area are agreed as to the quantity or quality of the service to be provided. The greatest degree of consensus can always be found at the lowest jurisdictional level, but this report argues that for the services selected for shifting, state financing will not result in service levels too different from any one municipality\u27s preferences. For example, there is not likely to be much dispute among municipal officials as to correctional institution standards. Third, the report recommends shifting services which have significant spill-in or spill-out characteristics; that is, when municipally-financed, they benefit or adversely affect residents of other local jurisdictions which have no voice in their delivery, on the one hand; and on the other hand, services with these characteristics involve costs without commensurate benefits to the responsible jurisdiction and eventually generate taxpayer resistance which forces severe reductions in service levels. Vocational education and transportation are two good examples of this phenomenon. The fourth criterion is that the area taxed to provide any service which effects a redistribution of services or cash (e.g. health and hospitals, veterans\u27 assistance) should include enough persons in both groups to make redistribution worthwhile: enough of those we wish to redistribute from and enough of those we wish to redistribute to. A great many municipalities in Massachusetts are somewhat internally homogeneous with respect to income; that is, the incomes of residents of any one community are likely to cluster. This tendency inhibits the provision of services with redistributive objectives which might significantly change the relative inequality of opportunity or well-being. In addition, the report notes that over-dependence on the local property tax has both inefficient and inequitable consequences which can be somewhat alleviated by any kind or measure of property tax relief