963 research outputs found

    Temperature Mapping of Nitrogen-Doped Niobium Superconducting Radiofrequency Cavities

    Get PDF
    It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping

    Nitrogen Doping Study in Ingot Niobium Cavities

    Get PDF
    Thermal diffusion of nitrogen in superconducting radio frequency cavities at temperatures around 800C has resulted in the increase in quality factor with a low-field Q-rise. However, the maximum accelerating gradients of these doped cavities often reduces below the values achieved by standard treatments. In this contribution, we present the results of the nitrogen diffusion into ingot niobium cavities subjected to successive material removal from the inner cavity surface by electropolishing in an effort to explore the underlying cause for the gradient degradation

    Control of Synchrotron Radiation Effects During Recirculation With Bunch Compression

    Get PDF
    Studies of beam quality preservation during recirculation * have been extended to generate a design of a compact arc providing bunch compression with positive momentum compaction ** and control of both incoherent and coherent synchrotron radiation (ISR and CSR) effects using the optics balance methods of diMitri et al.***. In addition, the arc/compressor generates very little micro-bunching gain. We detail the beam dynamical basis for the design, discuss the design process, give an example solution, and provide simulations of ISR and CSR effects. Reference will be made to a complete analysis of micro-bunching effects ****

    Goal-oriented cognitive rehabilitation for early-stage Alzheimer's and related dementias: the GREAT RCT

    Get PDF
    This is the author accepted manuscript. The final version is available from NIHR Journals Library via the DOI in this record.The published version is available in ORE at http://hdl.handle.net/10871/36867This study was funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme; PI Professor L Clare; HTA reference 11/15/04

    The importance of age effects on performance in the assessment of clinical trials

    Full text link
    Forty young adult normal subjects, 10 Parkinson's disease patients and their 10 matched normal subjects, and 10 multiple sclerosis patients and their 10 matched normal subjects were evaluated in the Quantitative Examination of Neurological Function to determine age effects and the importance of selecting closely matched normal control groups for assessing the performance of patients. Where there are significant differences among the three normal subject groups, it is the oldest normal subject group that differs from the two younger subject groups. Significant decreases in performance with increasing age were found for the steadiness tests performed in the supported position, the sensation tests, two or five tests in the Neuro-Psychological Examination and tests requiring fine skilled movements primarily with the dominant hand. It was found that older subjects made fewer errors in coordinated tasks.A normalization technique, expressing performance as a percentage of normal function, was introduced. A method was developed to provide quantitative and meaningful indices of neurological function. The measure is obtained by averaging the percentage of normal function scores over several tests that belong to a primary category of neurological function.Young adult normal subjects do not perform significantly better than normal subjects in the age range of multiple sclerosis patients; however, young adult normal subjects do perform significantly better than normal subjects in the age range of Parkinson's disease patients, especially on tasks requiring fine skilled movements of the dominant hand and coordinated activities of the lower extremities. These results indicate that the performance of multiple sclerosis patients can be expressed as a percentage of the function of either age-matched normal controls or young adult normal controls. However, the performance of Parkinson's disease patients should be expressed only as a percentage of the function of age-matched normal controls.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33791/1/0000046.pd

    Global Warming: Forecasts by Scientists versus Scientific Forecasts

    Get PDF
    In 2007, the Intergovernmental Panel on Climate Change’s Working Group One, a panel of experts established by the World Meteorological Organization and the United Nations Environment Programme, issued its Fourth Assessment Report. The Report included predictions of dramatic increases in average world temperatures over the next 92 years and serious harm resulting from the predicted temperature increases. Using forecasting principles as our guide we asked: Are these forecasts a good basis for developing public policy? Our answer is “no”. To provide forecasts of climate change that are useful for policy-making, one would need to forecast (1) global temperature, (2) the effects of any temperature changes, and (3) the effects of feasible alternative policies. Proper forecasts of all three are necessary for rational policy making. The IPCC WG1 Report was regarded as providing the most credible long-term forecasts of global average temperatures by 31 of the 51 scientists and others involved in forecasting climate change who responded to our survey. We found no references in the 1056-page Report to the primary sources of information on forecasting methods despite the fact these are conveniently available in books, articles, and websites. We audited the forecasting processes described in Chapter 8 of the IPCC’s WG1 Report to assess the extent to which they complied with forecasting principles. We found enough information to make judgments on 89 out of a total of 140 forecasting principles. The forecasting procedures that were described violated 72 principles. Many of the violations were, by themselves, critical. The forecasts in the Report were not the outcome of scientific procedures. In effect, they were the opinions of scientists transformed by mathematics and obscured by complex writing. Research on forecasting has shown that experts’ predictions are not useful in situations involving uncertainly and complexity. We have been unable to identify any scientific forecasts of global warming. Claims that the Earth will get warmer have no more credence than saying that it will get colder

    Limited receipt of support services among people with mild-to-moderate dementia: findings from the IDEAL cohort

    Get PDF
    YesBackground: Global initiatives that promote public health responses to dementia have resulted in numerous countries developing new national policies. Current policy guidelines in England, for example, recommend that people diagnosed with mild-to-moderate dementia receive information and psychosocial interventions to improve their ability to ‘live well’. However, it remains unclear to what extent these recommendations are being achieved. Methods: Self-reported information from 1537 people living with dementia and informant-reported information from 1277 carers of people living with dementia was used to quantify receipt of community-based dementia support services, including health and social care services provided by statutory or voluntary-sector organisations, in Britain from 2014 to 2016. Demographic factors associated with differences in receipt of support services were also investigated to identify particularly vulnerable groups of people living with dementia. Results: Both self- and informant reports suggested that approximately 50% of people living with dementia received support services for dementia. Receipt of support services was lower among people living with dementia who are older, female, and have fewer educational qualifications. Receipt of support services also differed according to diagnosis and carer status, but was unrelated to marital status. Conclusions: Limited receipt of dementia support services among people living with dementia in Britain provides a baseline to assess the efficacy of current policy guidelines regarding provision of information and support. Targeted efforts to facilitate receipt of support services among the particularly vulnerable groups identified in the current study could improve the efficacy of dementia support services both in Britain and internationally, and should inform policy development.The IDEAL study’ was funded jointly by the Economic and Social Research Council (ESRC) and the National Institute for Health Research (NIHR) through grant ES/L001853/2. The IDEAL‐2 study’ is funded by Alzheimer's Society, grant number 348,AS‐PR2‐16‐001

    Clinical delineation and natural history of the PIK3CA-related overgrowth spectrum.

    Get PDF
    Somatic mutations in the phosphatidylinositol/AKT/mTOR pathway cause segmental overgrowth disorders. Diagnostic descriptors associated with PIK3CA mutations include fibroadipose overgrowth (FAO), Hemihyperplasia multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi, Scoliosis/skeletal and spinal (CLOVES) syndrome, macrodactyly, and the megalencephaly syndrome, Megalencephaly-Capillary malformation (MCAP) syndrome. We set out to refine the understanding of the clinical spectrum and natural history of these phenotypes, and now describe 35 patients with segmental overgrowth and somatic PIK3CA mutations. The phenotypic data show that these previously described disease entities have considerable overlap, and represent a spectrum. While this spectrum overlaps with Proteus syndrome (sporadic, mosaic, and progressive) it can be distinguished by the absence of cerebriform connective tissue nevi and a distinct natural history. Vascular malformations were found in 15/35 (43%) and epidermal nevi in 4/35 (11%) patients, lower than in Proteus syndrome. Unlike Proteus syndrome, 31/35 (89%) patients with PIK3CA mutations had congenital overgrowth, and in 35/35 patients this was asymmetric and disproportionate. Overgrowth was mild with little postnatal progression in most, while in others it was severe and progressive requiring multiple surgeries. Novel findings include: adipose dysregulation present in all patients, unilateral overgrowth that is predominantly left-sided, overgrowth that affects the lower extremities more than the upper extremities and progresses in a distal to proximal pattern, and in the most severely affected patients is associated with marked paucity of adipose tissue in unaffected areas. While the current data are consistent with some genotype-phenotype correlation, this cannot yet be confirmed
    • 

    corecore