1,858 research outputs found
Nondestructive Electromagnetic Material Characterization using a Dual Waveguide Probe: A Full Wave Solution
A nondestructive technique for determining the complex permittivity and permeability of a perfect electric conductor backed magnetic shielding material using a dual waveguide probe is presented. The dual waveguide probe allows for the simultaneous collection of reflection and transmission coefficients which distinguishes it from single probe methods common in the literature. Theoretical development of these coefficients, which is accomplished through a coupled magnetic field integral equations formulation using Love\u27s equivalence principle and solved via the method of moments (MOM), is discussed. Evaluation of the resulting MOM impedance matrix elements is performed using complex plane integration leading to enhanced computational efficiency and physical insight. Comparison of the theoretical and measured reflection and transmission coefficients using a root finding algorithm leads to the desired permittivity and permeability. Measurement results of a magnetic shielding material are presented and compared to traditional methods for the purpose of validating the new technique. The probe\u27s sensitivity to aperture alignment, sample thickness, and flange thickness is also investigated.Abstract © AGU
Investigation of the demand for a 7-day (extended access) primary care service : an observational study from pilot schemes in England
Objectives: To understand how the uptake of an extended primary care service in the evenings and weekend varied by day of week and over time. Secondary objectives were to understand patient demographics of users of the service and how these varied by type of appointment and to core hour users.
Design: Observational study.
Setting: Primary care extended access appointments data in 13 centres in Greater Manchester, England, during 2016.
Participants: Appointments could be booked by 1 261 326 patients registered with a family practitioner in five Clinical Commissioning Group geographic areas.
Main outcome measures: Primary outcome measure was whether an appointment was used (booked and attended), secondary outcome measures included whether used appointments were prebooked or booked the same day, and delivered by a family or nurse practitioner. Additional analyses compared patient demographics with patients reporting the use of core hour primary care services.
Results: 65.33% of 42 472 appointments were booked and attended (used). Usage of appointments was lowest on a Sunday at 46.73% (18.07 percentage points lower usage than on Mondays (95% CI â32.46 to â3.68)). Prebooked appointments were less likely to be booked among age group 0â9 and to result in patients not attending an appointment. Family practitioner appointments were increasingly less likely to be booked with age in comparison to nurse appointments. Patients attending extended access appointments tended to be younger in comparison to core hour patients.
Conclusions: There is spare capacity in the extended access service, particularly on Sundays, suggesting reconfigurations of the service may be needed to improve efficiency of delivering the service. Patient demographics suggest the service is used by a relatively younger population than core hour services. Patient demographics varied with the types of appointment provided, these findings may help healthcare providers improve usage by tailoring appointment provision to local populations
The VLA Galactic Plane Survey
The VLA Galactic Plane Survey (VGPS) is a survey of HI and 21-cm continuum
emission in the Galactic plane between longitude 18 degrees 67 degr. with
latitude coverage from |b| < 1.3 degr. to |b| < 2.3 degr. The survey area was
observed with the Very Large Array (VLA) in 990 pointings. Short-spacing
information for the HI line emission was obtained by additional observations
with the Green Bank Telescope (GBT). HI spectral line images are presented with
a resolution of 1 arcmin x 1 arcmin x 1.56 km/s (FWHM) and rms noise of 2 K per
0.824 km/s channel. Continuum images made from channels without HI line
emission have 1 arcmin (FWHM) resolution. VGPS images are compared with images
from the Canadian Galactic Plane Survey (CGPS) and the Southern Galactic Plane
Survey (SGPS). In general, the agreement between these surveys is impressive,
considering the differences in instrumentation and image processing techniques
used for each survey. The differences between VGPS and CGPS images are small, <
6 K (rms) in channels where the mean HI brightness temperature in the field
exceeds 80 K. A similar degree of consistency is found between the VGPS and
SGPS. The agreement we find between arcminute resolution surveys of the
Galactic plane is a crucial step towards combining these surveys into a single
uniform dataset which covers 90% of the Galactic disk: the International
Galactic Plane Survey (IGPS). The VGPS data will be made available on the World
Wide Web through the Canadian Astronomy Data Centre (CADC).Comment: Accepted for publication in The Astronomical Journal. 41 pages, 13
figures. For information on data release, colour images etc. see
http://www.ras.ucalgary.ca/VGP
GSH23.0-0.7+117, a neutral hydrogen shell in the inner Galaxy
GSH23.0-0.7+117 is a well-defined neutral hydrogen shell discovered in the
VLA Galactic Plane Survey (VGPS). Only the blueshifted side of the shell was
detected. The expansion velocity and systemic velocity were determined through
the systematic behavior of the HI emission with velocity. The center of the
shell is at (l,b,v)=(23.05,-0.77,+117 km/s). The angular radius of the shell is
6.8', or 15 pc at a distance of 7.8 kpc. The HI mass divided by the volume of
the half-shell implies an average density n_H = 11 +/- 4 cm^{-3} for the medium
in which the shell expanded. The estimated age of GSH23.0-0.7+117 is 1 Myr,
with an upper limit of 2 Myr. The modest expansion energy of 2 * 10^{48} erg
can be provided by the stellar wind of a single O4 to O8 star over the age of
the shell. The 3 sigma upper limit to the 1.4 GHz continuum flux density
(S_{1.4} < 248 mJy) is used to derive an upper limit to the Lyman continuum
luminosity generated inside the shell. This upper limit implies a maximum of
one O9 star (O8 to O9.5 taking into account the error in the distance) inside
the HI shell, unless most of the incident ionizing flux leaks through the HI
shell. To allow this, the shell should be fragmented on scales smaller than the
beam (2.3 pc). If the stellar wind bubble is not adiabatic, or the bubble has
burst (as suggested by the HI channel maps), agreement between the energy and
ionization requirements is even less likely. The limit set by the non-detection
in the continuum provides a significant challenge for the interpretation of
GSH23.0-0.7+117 as a stellar wind bubble. A similar analysis may be applicable
to other Galactic HI shells that have not been detected in the continuum.Comment: 18 pages, 6 figures. Figures 1 and 4 separately in GIF format.
Accepted for publication in Astrophysical Journa
The Phenomenon of Exquisite Motor Control in Tic Disorders and its Pathophysiological Implications
The unifying characteristic of movement disorders is the phenotypic presentation of abnormal motor outputs, either as isolated phenomena or in association with further clinical, often neuropsychiatric, features. However, the possibility of a movement disorder also characterized by supranormal or enhanced volitional motor control has not received attention. Based on clinical observations and cases collected over a number of years, we here describe the intriguing clinical phenomenon that people with tic disorders are often able to control specific muscle contractions as part of their tic behaviors to a degree that most humans typically cannot. Examples are given in accompanying video documentation. We explore medical literature on this topic and draw analogies with early research of fine motor control physiology in healthy humans. By systematically analyzing the probable sources of this unusual capacity, and focusing on neuroscientific accounts of voluntary motor control, sensory feedback, and the role of motor learning in tic disorders, we provide a novel pathophysiological account explaining both the presence of exquisite control over motor output and that of overall tic behaviors. We finally comment on key questions for future research on the topic and provide concluding remarks on the complex movement disorder of tic behaviors
Polyphenols: A concise overview on the chemistry, occurrence, and human health
This review gives an updated picture of each class of phenolic compounds and their properties. The most common classification implies the subdivision of phenolics in two main groups: flavonoids (e.g., anthocyanins, flavanols, flavanones, flavonols, flavonones, and isoflavones) and non-flavonoids (e.g., phenolic acids, xanthones, stilbens, lignans, and tannins) polyphenols. The great interest in polyphenols is associated with their high potential application for food preservation and for therapeutic beneficial use. The relationship between polyphenol intake and human health has been exploited with special reference to cardiovascular diseases, hypertension, diabetes, metabolic syndrome, obesity, and cancer. The use of current existing databases of bioactive compounds including polyphenols is described as key tools for human health research.info:eu-repo/semantics/publishedVersio
Obesity: A Biobehavioral Point of View
Excerpt: If you ask an overweight person, âWhy are you fat?â, you will, almost invariably, get the answer, âBecause 1 eat too much.â You will get this answer in spite of the fact that of thirteen studies, six find no significant differences in the caloric intake of obese versus nonobese subjects, five report that the obese eat significantly less than the nonobese, and only two report that they eat significantly more
BIANCA (Brain Intensity AbNormality Classification Algorithm): a new tool for automated segmentation of white matter hyperintensities
Reliable quantification of white matter hyperintensities of presumed vascular origin (WMHs) is increasingly needed, given the presence of these MRI findings in patients with several neurological and vascular disorders, as well as in elderly healthy subjects. We present BIANCA (Brain Intensity AbNormality Classification Algorithm), a fully automated, supervised method for WMH detection, based on the k-nearest neighbour (k-NN) algorithm. Relative to previous k-NN based segmentation methods, BIANCA offers different options for weighting the spatial information, local spatial intensity averaging, and different options for the choice of the number and location of the training points. BIANCA is multimodal and highly flexible so that the user can adapt the tool to their protocol and specific needs. We optimised and validated BIANCA on two datasets with different MRI protocols and patient populations (a âpredominantly neurodegenerativeâ and a âpredominantly vascularâ cohort). BIANCA was first optimised on a subset of images for each dataset in terms of overlap and volumetric agreement with a manually segmented WMH mask. The correlation between the volumes extracted with BIANCA (using the optimised set of options), the volumes extracted from the manual masks and visual ratings showed that BIANCA is a valid alternative to manual segmentation. The optimised set of options was then applied to the whole cohorts and the resulting WMH volume estimates showed good correlations with visual ratings and with age. Finally, we performed a reproducibility test, to evaluate the robustness of BIANCA, and compared BIANCA performance against existing methods. Our findings suggest that BIANCA, which will be freely available as part of the FSL package, is a reliable method for automated WMH segmentation in large cross-sectional cohort studies. © 2016 The Author
Compact HI clouds at high forbidden velocities in the inner Galaxy
The VLA Galactic Plane Survey (VGPS) of the first Galactic quadrant was
searched for HI emission with velocities well above the maximum velocity
allowed by Galactic rotation. A sample of 17 small fast-moving clouds was
identified. The distribution of the ensemble of clouds in longitude and
velocity indicates that the clouds are part of the Galactic disk, despite their
large forbidden velocity. The median angular diameter of the clouds detected in
the VGPS is 3.4 arcminutes. These clouds would not be noticed in previous low
resolution surveys because of strong beam dilution. Assuming each cloud is
located at the tangent point, a median cloud has a diameter of 10 pc, HI mass
of 60 M_sun, and a velocity more than 25 km/s beyond the local terminal
velocity derived from 12CO observations. Three clouds in the sample have a
velocity between 50 and 60 km/s in excess of the local terminal velocity. The
longitude distribution of the sample peaks near l = 30 degrees, while the
latitude distribution of the clouds is nearly flat. The observed longitude and
latitude distributions are compared with simulated distributions taking into
account the selection criteria of the cloud search. It is found that the number
of clouds declines with distance from the Galactic center, with an exponential
scale length 2.8 - 8 kpc at the 99% confidence level. We find a lower limit to
the scale height of the clouds of 180 pc (HWHM), but the true value is likely
significantly higher.Comment: Accepted for publication in The Astrophysical Journal. 28 pages, 10
figures of which 3 as separate jpg file
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