11,897 research outputs found
2D-Oide effect
The Oide effect considers the synchrotron radiation in the final focusing
quadrupole and it sets a lower limit on the vertical beam size at the
Interaction Point, particularly relevant for high energy linear colliders. The
theory of the Oide effect was derived considering only the radiation in the
focusing plane of the magnet. This article addresses the theoretical
calculation of the radiation effect on the beam size consider- ing both
focusing and defocusing planes of the quadrupole, refered to as 2D-Oide. The
CLIC 3 TeV final quadrupole (QD0) and beam parameters are used to compare the
theoretical results from the Oide effect and the 2D-Oide effect with particle
tracking in PLACET. The 2D-oide demonstrates to be important as it increases by
17% the contribution to the beam size. Further insight into the aberrations
induced by the synchrotron radiation opens the possibility to partially correct
the 2D-Oide effect with octupole mag
Infrared spectroscopy of the dwarf starburst galaxy Henize 2-10
Researchers present 1.2 to 2.2 micron spectra of the nucleus of Henize 2 to 10, taken at United Kingdom Infrared Telescope (UKIRT) with the cool grating spectrometer 2 (CGS 2). This galaxy displays strong line emission from interstellar H (+) (1.282 and 2.166 microns) and (Fe (+)) (1.256 and 1.644 microns), in common with other star-forming galaxy nuclei. However, the 1 to 0 S(1) line of molecular hydrogen at 2.122 micron is not detected - the upper limit of 0.15 (3 sigma) for the value of the flux ratio I sub 1-os(1)/I sub Br gamma is much lower than the typical values of 0.4 to 0.9 measured in a sample of 28 non-interacting starburst galaxies. From the Pa beta/Br gamma line ratio researchers derive a total extinction of A sub v approx. 4 mag. The de-reddened H (+) and (Fe (+) line fluxes are used to estimate the total ionizing luminosity and the average supernova rate in the central 150 pc of He 2 to 10. By comparison of these estimates with existing Infrared Astronomy Satellite (IRAS) and radio continuum data, researchers are able to set limits on the range of stellar masses present in this unevolved (less than 10(exp 7) year old) starburst nucleus. Possible reasons for the low H2/H+ line ratios observed in young starburst systems (He 2 to 10, NGC 7714, IIZw40; e.g., Moorwood and Oliva 1988) are briefly discussed
Resistive plate chambers for time-of-flight measurements
The applications of Resistive Plate Chambers (RPCs) have recently been
extended by the development of counters with time resolution below 100 ps sigma
for minimum ionising particles. Applications to HEP experiments have already
taken place and many further applications are under study. In this work we
address the operating principles of such counters along with some present
challenges, with emphasis on counter aging.Comment: Presented at "PSD6 - 6th International Conference on Position
Sensitive Detectors", 9-13 September 2002, Leicester, UK. Submitted to
Nuclear Instruments and Methods
Intersection between class and gender and its effect on the quality of employment in Chile
IndexaciĂłn: Web of Science; Scopus.En este artĂculo se analiza el efecto de la intersecciĂłn entre clase y gĂ©nero sobre la calidad
del empleo en Chile. La medida de posiciĂłn de clase utilizada estĂĄ basada en la propuesta de
Erik O. Wright y la calidad del empleo en una medida multidimensional, que incluye un Ăndice
de condiciones objetivas de empleo y dos Ăndices de condiciones subjetivas (motivaciĂłn en
el trabajo y percepciĂłn del control sobre el proceso de trabajo). Los resultados demuestran
que la clase y el género determinan diferencias significativas en la calidad objetiva y subjetiva
del empleo. Sin embargo, los datos también indican que el género (particularmente, el
hecho de ser mujer) no actĂșa necesariamente como âamplificadorâ de las desigualdades
de clase observadas en el mercado laboral. A partir de esto, al final del artĂculo se plantean
algunas reflexiones sobre cómo opera la intersección entre clase y género en el mercado
laboral chileno.This study explores the impact of the intersection between class and gender on the quality
of employment in Chile. The method used to measure social class position is based on the
work of Erik O. Wright, while, for the quality of employment, a multidimensional measurement
was used, including one index for objective working conditions and two indices for subjective
ones (motivation on the job and the perception of control over work processes). The results
demonstrate that class and gender give rise to signifcant differences in objective and
subjective job quality. However, the data also indicate that gender (more specifcally, the fact
of being female) does not necessarily amplify the class-based inequalities observed in the
labour market. Drawing on these fndings, a number of thoughts about how the class/gender
intersection operates in the Chilean labour market are shared in the fnal section of this studyhttp://hdl.handle.net/11362/4079
Progression from ocular hypertension to visual field loss in the English hospital eye service
Background There are more than one million National Health Service visits in England and Wales each year for patients with glaucoma or ocular hypertension (OHT). With the ageing population and an increase in optometric testing, the economic burden of glaucoma-related visits is predicted to increase. We examined the conversion rates of OHT to primary open-angle glaucoma (POAG) in England and assessed factors associated with risk of conversion.
Methods Electronic medical records of 45â309 patients from five regionally different glaucoma clinics in England were retrospectively examined. Conversion to POAG from OHT was defined by deterioration in visual field (two consecutive tests classified as stage 1 or worse as per the glaucoma staging system 2). Cox proportional hazards models were used to examine factors (age, sex, treatment status and baseline intraocular pressure (IOP)) associated with conversion.
Results The cumulative risk of conversion to POAG was 17.5% (95% CI 15.4% to 19.6%) at 5 years. Older age (HR 1.35 per decade, 95%âCI 1.22 to 1.50, p<0.001) was associated with a higher risk of conversion. IOP-lowering therapy (HR 0.45, 95%âCI 0.35 to 0.57, p<0.001) was associated with a lower risk of conversion. Predicted 5-year conversion rates for treated and untreated groups were 14.0% and 26.9%, respectively.
Conclusion Less than one-fifth of OHT patients managed in glaucoma clinics in the UK converted to POAG over a 5-year period, suggesting many patients may require less intensive follow-up. Our study provides real-world evidence for the efficacy of current management (including IOP-lowering treatment) at reducing risk of conversion
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Relationship between thoracic kyphosis and neural axis abnormalities in patients with adolescent idiopathic scoliosis.
Purpose:Previous studies have suggested an association between increased thoracic kyphosis and neural axis abnormalities in patients with adolescent idiopathic scoliosis (AIS). However, the basis for this finding is unclear, and this association has been mainly noted in retrospective studies on a non-consecutive series of patients. The purpose of this study was to assess the relationship between thoracic kyphosis and neural axis abnormalities in patients with AIS. Methods:We studied a consecutive series of AIS patients treated with spinal fusion. Thoracic kyphosis (T2 to T12) was measured from preoperative lateral radiographs. All patients underwent a spine magnetic resonance imaging (MRI) prior to surgery, and MRI reports were reviewed to determine the presence of neural axis abnormalities. Statistical analyses included descriptive statistics and chi-squared analysis. Results:This study included 210 patients with AIS. There were no significant differences in age or gender between patients with thoracic hypokyphosis (kyphosis < 20°), normal thoracic kyphosis (kyphosis 20° to 40°) and thoracic hyperkyphosis (kyphosis > 40°) (p > 0.05). Neural axis abnormalities were present in 17.9% of patients with thoracic hypokyphosis, 9.8% of patients with normal thoracic kyphosis and 13.6% of patients with thoracic hyperkyphosis (p = 0.60). There were no significant differences in rates of Chiari malformation, syrinx, intra-spinal masses and other central nervous system abnormalities between groups (p > 0.05). Conclusions:Thoracic kyphosis was not associated with neural axis abnormalities in our consecutive series of patients with AIS. Increased thoracic kyphosis may not be a reliable indicator for the presence of neural axis abnormalities in patients with AIS. Level of Evidence:IV
Fluctuation Analysis of Human Electroencephalogram
The scaling behaviors of the human electroencephalogram (EEG) time series are
studied using detrended fluctuation analysis. Two scaling regions are found in
nearly every channel for all subjects examined. The scatter plot of the scaling
exponents for all channels (up to 129) reveals the complicated structure of a
subject's brain activity. Moment analyses are performed to extract the gross
features of all the scaling exponents, and another universal scaling behavior
is identified. A one-parameter description is found to characterize the
fluctuation properties of the nonlinear behaviors of the brain dynamics.Comment: 4 pages in RevTeX + 6 figures in ep
CLIC 3 TeV Beam size Optimization with Radiation Effects
TUPWO003 - ISBN 978-3-95450-122-9International audienceHorizontal beamsize contribution due to radiation on bending magnets is calculated using theoretical results and recent improvements in mapclass (Mapclass2). In order to verify the code and validity of its approximations, a simple lattice with no geometrical nor chromatic aberrations, one dipole and a final drift has been used to compareMapclass2 calculations and Placet tracking results. CLIC 3TeV lattice is optimized including the radiation effects. Current results show that correction of chromatic aberrations impose constraints in radiation improvement
Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window
Aims: We seek to provide 2MASS and OGLE identifications and coordinates for
all stars in the finding chart published by Arp\,(1965). This chart covers the
low extinction area around NGC 6522, also known as Baade's window, at
coordinates (l,b)=(1.02,-3.92).
Methods: A cross correlation, using numerical techniques, was performed
between a scan of the original finding chart from Arp (1965) and 2MASS and
OGLE-II images and stellar coordinates.
Results: We provide coordinates for all stars in Arp's finding chart and
2MASS and OGLE identifications wherever possible. Two identifications in
quadrant II do not appear in the original finding chart.Comment: 30 pages, accepted by A&A as a Research Not
Faint Infrared Flares from the Microquasar GRS 1915+105
We present simultaneous infrared and X-ray observations of the Galactic
microquasar GRS 1915+105 using the Palomar 5-m telescope and Rossi X-ray Timing
Explorer on July 10, 1998 UT. Over the course of 5 hours, we observed 6 faint
infrared (IR) flares with peak amplitudes of mJy and durations
of seconds. These flares are associated with X-ray
soft-dip/soft-flare cycles, as opposed to the brighter IR flares associated
with X-ray hard-dip/soft-flare cycles seen in August 1997 by Eikenberry et al.
(1998). Interestingly, the IR flares begin {\it before} the X-ray oscillations,
implying an ``outside-in'' origin of the IR/X-ray cycle. We also show that the
quasi-steady IR excess in August 1997 is due to the pile-up of similar faint
flares. We discuss the implications of this flaring behavior for understanding
jet formation in microquasars.Comment: 10 pages, 4 figures Accepted for publication in ApJ Letter
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