1,232 research outputs found
Recommended from our members
The Emergence of Barriers to Wh-movement, Negative Concord, and Quantification
Experiments on sedimentation in wide reservoirs and erosion following dam removal
River morphodynamics and sediment transportSedimentation in reservoir
Primary beam effects of radio astronomy antennas -- II. Modelling the MeerKAT L-band beam
After a decade of design and construction, South Africa's SKA-MID precursor
MeerKAT has begun its science operations. To make full use of the widefield
capability of the array, it is imperative that we have an accurate model of the
primary beam of its antennas. We have taken available L-band full-polarization
'astro-holographic' observations of three antennas and a generic
electromagnetic simulation and created sparse representations of the beams
using principal components and Zernike polynomials. The spectral behaviour of
the spatial coefficients has been modelled using discrete cosine transform. We
have provided the Zernike-based model over a diameter of 10 deg averaged over
the beams of three antennas in an associated software tool (EIDOS) that can be
useful in direction-dependent calibration and imaging. The model is more
accurate for the diagonal elements of the beam Jones matrix and at lower
frequencies. As we get more accurate beam measurements and simulations in the
future, especially for the cross-polarization patterns, our pipeline can be
used to create more accurate sparse representations of MeerKAT beams.Comment: 16 pages, 18 figures. This is a pre-copyedited, author-produced PDF
of an article accepted for publication in MNRAS following peer review. The
version of record [K. M. B. Asad et al., 2021] is available online at:
https://doi.org/10.1093/mnras/stab10
Cohort profile: biological pathways of risk and resilience in Syrian refugee children (BIOPATH)
The BIOPATH cohort was established to explore the interplay of psychosocial and biological factors in the development of resilience and mental health problems in Syrian refugee children. Based in Lebanon, a middle-income country significantly impacted by the refugee crisis, it is the first such cohort of refugees in the Middle East. Families were recruited from informal tented settlements in the Beqaa region using purposive cluster sampling. At baseline (October 2017–January 2018), N = 3188 individuals participated [n = 1594 child–caregiver dyads; child gender, 52.6% female; mean (SD) age = 11.44 (2.44) years, range = 6–19]. Re-participation rate at 1-year follow-up was 62.8%. Individual interviews were conducted with children and primary caregivers and biological samples collected from children. Measures include: (1) children’s well-being and mental health problems (using tools validated against clinical interviews in a subsample of the cohort); (2) psychosocial risk and protective factors at the level of the individual (e.g. coping strategies), family (e.g. parent–child relationship), community (e.g. collective efficacy), and wider context (e.g. services); (3) saliva samples for genetic and epigenetic (methylation) analyses; (4) hair samples to measure cortisol, dehydroepiandrosterone (DHEA) and testosterone. This cohort profile provides details about sampling and recruitment, data collection and measures, demographic data, attrition and potential bias, key findings on resilience and mental health problems in children and strengths and limitations of the cohort. Researchers interested in accessing data should contact Professor Michael Pluess at Queen Mary University of London, UK (e-mail: [email protected]). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00127-022-02228-8
Books
Brain work Brain Work and Mental Activity: Quantitative Studies with Radioactive Tracers. Ed. by N. A. Lassen, D. H. Ingvar, M. E. RaicWe and L. Friberg. Pp. 446. Illustrated. Copenhagen: Munksgaard. 1991.Neuroanatomy Neuroanatomy for Medical Students. 2nd ed. By ]. L. Wilkinson. pp. x + 307. illustrated. Oxford: Butterworth Heinemann. 1992.Atherosclerosis Molecular Biology of Atherosclerosis: Proceedings of the 57th European Atherosclerosis Society Meeting. Ed. by M. J. Halpern. Pp. xv + 662. Illustrated. ÂŁ45. London: John libbey. 1992.Antibiotics Antibiotic Guidelines. By H. J. Koomhof and L. D. Liebowitz. pp. 122. Pretoria: JL van Schaik. 1991.Reproductive medicine Reproduction, Growth and Development. By A. Negro-Vilar and G. perez-Palacios. Pp. xv + 440. illustrated. $162,50. New York: Raven Press. 1991.Obesity research Progress in Obesity Research 1990. Ed. by Y. Oomura, S. Tarui, S. Inoue and T. Shimazu. Pp. xiii + 688. illustrated. ÂŁ17,50. London: John Libbey. 1991.Epidemiology Fetal and Infant Origins of Adult Disease. Ed. by D.}. P. Barker. Pp. xv + 343. ÂŁ30. London: BM}. 1992
Conductance of the single-electron transistor: A comparison of experimental data with Monte Carlo calculations
We report on experimental results for the conductance of metallic
single-electron transistors as a function of temperature, gate voltage and
dimensionless conductance. In contrast to previous experiments our transistor
layout allows for a direct measurement of the parallel conductance and no ad
hoc assumptions on the symmetry of the transistors are necessary. Thus we can
make a comparison between our data and theoretical predictions without any
adjustable parameter. Even for rather weakly conducting transistors significant
deviations from the perturbative results are noted. On the other hand, path
integral Monte Carlo calculations show remarkable agreement with experiments
for the whole range of temperatures and conductances.Comment: 8 pages, 7 figures, revtex4, corrected typos, submitted to PR
Presence of papillomavirus sequences in condylomatous lesions of the mamillae and in invasive carcinoma of the breast
BACKGROUND: Viruses including Epstein–Barr virus (EBV), a human equivalent of murine mammary tumour virus (MMTV) and human papillomavirus (HPV) have been implicated in the aetiology of human breast cancer. We report the presence of HPV DNA sequences in areolar tissue and tumour tissue samples from female patients with breast carcinoma. The presence of virus in the areolar–nipple complex suggests to us a potential pathogenic mechanism. METHODS: Polymerase chain reaction (PCR) was undertaken to amplify HPV types in areolar and tumour tissue from breast cancer cases. In situ hybridisation supported the PCR findings and localised the virus in nipple, areolar and tumour tissue. RESULTS: Papillomavirus DNA was present in 25 of 29 samples of breast carcinoma and in 20 of 29 samples from the corresponding mamilla. The most prevalent type in both carcinomas and nipples was HPV 11, followed by HPV 6. Other types detected were HPV 16, 23, 27 and 57 (nipples and carcinomas), HPV 20, 21, 32, 37, 38, 66 and GA3-1 (nipples only) and HPV 3, 15, 24, 87 and DL473 (carcinomas only). Multiple types were demonstrated in seven carcinomas and ten nipple samples. CONCLUSIONS: The data demonstrate the occurrence of HPV in nipple and areolar tissues in patients with breast carcinoma. The authors postulate a retrograde ductular pattern of viral spread that may have pathogenic significance
On the Polish doughnut accretion disk via the effective potential approach
We revisit the Polish doughnut model of accretion disks providing a
comprehensive analytical description of the Polish doughnut structure. We
describe a perfect fluid circularly orbiting around a Schwarzschild black hole,
source of the gravitational field, by the effective potential approach for the
exact gravitational and centrifugal effects. This analysis leads to a detailed,
analytical description of the accretion disk, its toroidal surface, the
thickness, the distance from the source. We determine the variation of these
features with the effective potential and the fluid angular momentum. Many
analytical formulas are given. In particular it turns out that the distance
from the source of the inner surface of the torus increases with increasing
fluid angular momentum but decreases with increasing energy function defined as
the value of the effective potential for that momentum. The location of torus
maximum thickness moves towards the external regions of the surface with
increasing angular momentum, until it reaches a maximum an then decreases.
Assuming a polytropic equation of state we investigate some specific cases.Comment: 33 pages, 28 figures, 1 table. This is a revised version to meet the
published articl
Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and
NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a
quiescent state since at least early 2015, reactivated between 2017 March 19
and April 5. The radio flux density, while variable, is approximately 100x
larger than during its dormant state. The X-ray flux one month after
reactivation was at least 800x larger than during quiescence, and has been
decaying exponentially on a 111+/-19 day timescale. This high-flux state,
together with a radio-derived rotational ephemeris, enabled for the first time
the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV
pulsed fraction is comparable to the smallest observed for magnetars. The
overall pulsar geometry inferred from polarized radio emission appears to be
broadly consistent with that determined 6-8 years earlier. However, rotating
vector model fits suggest that we are now seeing radio emission from a
different location in the magnetosphere than previously. This indicates a novel
way in which radio emission from magnetars can differ from that of ordinary
pulsars. The torque on the neutron star is varying rapidly and unsteadily, as
is common for magnetars following outburst, having changed by a factor of 7
within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure
- …