169,611 research outputs found
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Quantum motion of a squeezed mechanical oscillator attained via an optomechanical experiment
No full textWe experimentally investigate a mechanical squeezed state realized in a parametrically modulated membrane resonator embedded in an optical cavity. We demonstrate that a quantum characteristic of the squeezed dynamics can be revealed and quantified even in a moderately warm oscillator, through the analysis of motional sidebands. We provide a theoretical framework for quantitatively interpreting the observations and present an extended comparison with the experiment. A notable result is that the spectral shape of each motional sideband provides a clear signature of a quantum mechanical squeezed state without the necessity of absolute calibrations, in particular in the regime where residual fluctuations in the squeezed quadrature are reduced below the zero-point level. </p
Special Issue — From Foundations of Quantum Mechanics to Quantum Information and Quantum Metrology & Sensing, “Quantum 2017”; Author Index Volume 15 (2017)
No full textSpondyloarthritis: A journey within and around the joint
No full textImaging has always been an integral part of the assessment of SpA. This group of diseases involving the axial skeleton and peripheral joints is a particularly intriguing area for sonographers, because it requires the evaluation of both articular and extra-articular regions. Among extra-articular features enthesitis has recently emerged as an area of special interest for both basic science and clinical researchers as well as for those working in the field of musculoskeletal imaging. This review provides information about research in this area focusing on the current concept and definition of enthesitis by US. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved
The safety and effectiveness of different methods of ear wax removal: a systematic review and economic evaluation
No full textEar wax (cerumen) is a natural secretion produced to protect the inner ear from dirt and other fragments by moving these particles towards the outer ear. If this process does not happen properly, wax may build up causing blockage in the ear canal and the possibility of impaction. People with a build up of ear wax may suffer from hearing loss, discomfort and, on occasions, infection. It may present problems in assessing hearing, blocking the view of the ear drum during medical examination and interfering with the fitting or function of hearing aids. Although it is thought to affect between 2% and 6% of the population in the England and Wales, some groups may be at a higher risk, such as those using hearing aids or with small ear canals and/or skin conditions. Recurrence is thought to be high among some of these groups. The consequences of the build up of ear wax in the ear canal are thought to be a common reason for consultation and cost in general practice with over 2 million consultations per year in the NHS.Methods of removal of ear wax include drops, flushing with water in general practice, and removal with suction or probes in specialist clinics. The relative safety and benefits of these different methods of removal remains uncertain. This research will systematically review published and unpublished evidence on the clinical and cost effectiveness of different methods for the removal of ear wax. Where appropriate, it will develop an economic model using data from this systematic review and other relevant sources to estimate the relative costs and benefits of different methods. In addition, the project will provide recommendations for future research to try to help answer any remaining areas of uncertainty
Direct P-Wave Seismic Noise Interferometry for Groundwater Monitoring: A Modelling Study
No full textIn this study, we monitor the depth variation of an unconfined aquifer by applying seismic noise interferometry to synthetic data modelled with a 2D finite-difference software. We consider two models with the same subsurface geological structure, but with different water table levels representing two monitoring periods. The receivers are placed at the topographic surface and collect the seismic signals generated by a source located at the bottom of the aquifer to simulate a pumping system. First, cross-correlation of seismic traces with a reference one is used to produce interferograms (i.e., virtual surveys) for both the tested models. Then, direct P-wave arrivals identified in the two interferograms are compared through the stretching technique in order to estimate the relative velocity changes (dv/v). Finally, the estimated dv/v values are related to theoretical ones obtained using a reference subsurface model to produce the water level depth in the considered monitoring period.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Applied Geophysics and Petrophysic
Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis
No full textMultiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis
Interaction between a large bubble and turbulence
No full textBubble dynamics in turbulent flows has been extensively studied using the point-bubble approximation. But when the carrier flow varies on length scales smaller than the bubble size, this approximation is no longer appropriate and one needs to resolve all the scales present in the two-phase flow. 3D Direct Numerical Simulations of turbulent bubbly flows are carried out for bubbles ten times larger than the Kolmogorov length scale. The dynamics of large bubbles subjected to homogeneous isotropic turbulence and the turbulence modulation induced by their presence are investigated by mean of conditional statistics
Dante "demonstrator" nel secondo libro della "Monarchia"
No full textAnalysis of Dante's Monarchia, II, 1-2, in order to demonstrate the scientifical methodology of the author in his treatise
Entrainment of a turbulent patch in a stratified fluid
No full textTurbulent patches are localized events of turbulence, typically characterized by sharp differences between the flow characteristics across their interfaces. These localized events might add to the global mixing, heat exchange and mass transfer, playing a non-negligible role in the total energy balance in lakes or the ocean. This study takes a detailed look at the inner structure of a localized, mechanically forced patch in a linearly stratified ambient using laboratory experiments utilizing synchronized PIV and PLIF. The results point out that the role of the turbulent/non-turbulent interface at the edge of the patch could be significant in determining the growth rate and the maximum size of the patch
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