343 research outputs found
Absolute radiometric calibration of the EUNIS-06 170-205 A channel and calibration update for CDS/NIS
The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding-rocket payload
was flown on 2006 April 12 (EUNIS-06), carrying two independent imaging
spectrographs covering wave bands of 300-370 A in first order and 170-205 A in
second order, respectively. The absolute radiometric response of the EUNIS-06
long-wavelength (LW) channel was directly measured in the same facility used to
calibrate CDS prior to the SOHO launch. Because the absolute calibration of the
short-wavelength (SW) channel could not be obtained from the same lab
configuration, we here present a technique to derive it using a combination of
solar LW spectra and density- and temperature-insensitive line intensity
ratios. The first step in this procedure is to use the coordinated, cospatial
EUNIS and SOHO/CDS spectra to carry out an intensity calibration update for the
CDS NIS-1 waveband, which shows that its efficiency has decreased by a factor
about 1.7 compared to that of the previously implemented calibration. Then,
theoretical insensitive line ratios obtained from CHIANTI allow us to determine
absolute intensities of emission lines within the EUNIS SW bandpass from those
of cospatial CDS/NIS-1 spectra after the EUNIS LW calibration correction. A
total of 12 ratios derived from intensities of 5 CDS and 12 SW emission lines
from Fe Fe X - Fe XIII yield an instrumental response curve for the EUNIS-06 SW
channel that matches well to a relative calibration which relied on combining
measurements of individual optical components. Taking into account all
potential sources of error, we estimate that the EUNIS-06 SW absolute
calibration is accurate to about 20%.Comment: 11 pages, 10 figures, 4 tables. 2010, ApJ Suppl. In pres
Presumed Diffuse Unilateral Subacute Neuroretinitis: A Review Supported by a Unique Case
Diffuse unilateral subacute neuroretinitis (DUSN) is a rare, sight-threatening inflammatory condition caused by a nematode. It typically affects healthy children and young adults. Various nematodes have been implicated, including those that originate from dogs and raccoons. Late stage findings include optic nerve atrophy, retinal arterial attenuation, “retinitis pigmentosa-like” retinal pigmentary changes, and central and peripheral vision loss. We present a case study of long-standing DUSN. The combination of optical coherence tomography (OCT) and visual electrophysiology testing proved invaluable in establishing a presumptive diagnosis of this rare condition
Parameters for successful nonoperative management of traumatic aortic injury
ObjectiveBlunt traumatic aortic injury is associated with significant mortality, and increased computed tomography use identifies injuries not previously detected. This study sought to define parameters identifying patients who can benefit from medical management.MethodsWe reviewed 4.5 years of blunt traumatic aortic injuries. Injury was classified as grade I (intimal flap or intramural hematoma), II (small pseudoaneurysm <50% circumference), III (large pseudoaneurysm >50% circumference), and IV (rupture/transection). Secondary signs of injury included pseudocoarctation, extensive mediastinal hematoma, and large left hemothorax. Follow-up, including computed tomography, was reviewed.ResultsWe identified 97 patients: 31 grade I, 35 grade II, 24 grade III, and 7 grade IV; 67(69%) male; mean age 47 ± 18.8 years, mean Injury Severity Score 38.8 ± 14.6; overall survival 76 (78.4%). Secondary signs of injury were found in 30 patients. Overall, 52 (53.6%) underwent repair, 45 undergoing thoracic endovascular aortic repair, with 2 (2.22%) procedure-related deaths, and 7 undergoing open repair. Five patients undergoing thoracic endovascular aortic repair required 7 additional procedures. In 45 medically managed patients, there were 14 deaths (31%), all secondary to associated injuries. Injury Severity Scores of survivors and nonsurvivors were 33 ± 10.8 and 48.6 ± 12.8, respectively (P < .001). Follow-up showed resolution or no change in 21 (91%) and a small increase in 2 grade I injuries.ConclusionsAll blunt traumatic aortic injury does not necessitate repair. Stratification by injury grade and secondary signs of injury identifies patients appropriate for medical management. Grade IV injury necessitates emergency procedures and carries high mortality. Grade III injury with secondary signs of injury should be urgently repaired; patients without secondary signs of injury may undergo delayed repair. Grade I and II injuries are amenable to medical management
Spherical Occulter Coronagraph Cubesat
The present invention relates to a space-based instrument which provides continuous coronal electron temperature and velocity images, for a predetermined period of time, thereby improving the understanding of coronal evolution and how the solar wind and Coronal Mass Ejection transients evolve from the low solar atmosphere through the heliosphere for an entire solar rotation. Specifically, the present invention relates to using a 6U spherical occulter coronagraph CubeSat, and a relative navigational system (RNS) that controls the position of the spacecraft relative to the occulting sphere. The present invention innovatively deploys a free-flying spherical occulter, and after deployment, the actively controlled CubeSat will provide an inertial formation flying with the spherical occulter and Sun
Underflight calibration of SOHO/CDS and Hinode/EIS with EUNIS-07
Flights of Goddard Space Flight Center's Extreme-Ultraviolet Normal-Incidence
Spectrograph (EUNIS) sounding rocket in 2006 and 2007 provided updated
radiometric calibrations for SOHO/CDS and Hinode/EIS. EUNIS carried two
independent imaging spectrographs covering wavebands of 300-370 A in first
order and 170-205 A in second order. After each flight, end-to-end radiometric
calibrations of the rocket payload were carried out in the same facility used
for pre-launch calibrations of CDS and EIS. During the 2007 flight, EUNIS, SOHO
CDS and Hinode EIS observed the same solar locations, allowing the EUNIS
calibrations to be directly applied to both CDS and EIS. The measured CDS NIS 1
line intensities calibrated with the standard (version 4) responsivities with
the standard long-term corrections are found to be too low by a factor of 1.5
due to the decrease in responsivity. The EIS calibration update is performed in
two ways. One is using the direct calibration transfer of the calibrated
EUNIS-07 short wavelength (SW) channel. The other is using the insensitive line
pairs, in which one member was observed by EUNIS-07 long wavelength (LW)
channel and the other by EIS in either LW or SW waveband. Measurements from
both methods are in good agreement, and confirm (within the measurement
uncertainties) the EIS responsivity measured directly before the instrument's
launch. The measurements also suggest that the EIS responsivity decreased by a
factor of about 1.2 after the first year of operation. The shape of the EIS SW
response curve obtained by EUNIS-07 is consistent with the one measured in
laboratory prior to launch. The absolute value of the quiet-Sun He II 304 A
intensity measured by EUNIS-07 is consistent with the radiance measured by CDS
NIS in quiet regions near the disk center and the solar minimum irradiance
obtained by CDS NIS and SDO/EVE recently.Comment: 16 pages, 14 figures, 5 tables, accepted by ApJ Supplement (Sep.
2011
Probabilistic Algorithmic Knowledge
The framework of algorithmic knowledge assumes that agents use deterministic
knowledge algorithms to compute the facts they explicitly know. We extend the
framework to allow for randomized knowledge algorithms. We then characterize
the information provided by a randomized knowledge algorithm when its answers
have some probability of being incorrect. We formalize this information in
terms of evidence; a randomized knowledge algorithm returning ``Yes'' to a
query about a fact \phi provides evidence for \phi being true. Finally, we
discuss the extent to which this evidence can be used as a basis for decisions.Comment: 26 pages. A preliminary version appeared in Proc. 9th Conference on
Theoretical Aspects of Rationality and Knowledge (TARK'03
Thermal phases of D1-branes on a circle from lattice super Yang-Mills
We report on the results of numerical simulations of 1+1 dimensional SU(N)
Yang-Mills theory with maximal supersymmetry at finite temperature and
compactified on a circle. For large N this system is thought to provide a dual
description of the decoupling limit of N coincident D1-branes on a circle. It
has been proposed that at large N there is a phase transition at strong
coupling related to the Gregory-Laflamme (GL) phase transition in the
holographic gravity dual. In a high temperature limit there was argued to be a
deconfinement transition associated to the spatial Polyakov loop, and it has
been proposed that this is the continuation of the strong coupling GL
transition. Investigating the theory on the lattice for SU(3) and SU(4) and
studying the time and space Polyakov loops we find evidence supporting this. In
particular at strong coupling we see the transition has the parametric
dependence on coupling predicted by gravity. We estimate the GL phase
transition temperature from the lattice data which, interestingly, is not yet
known directly in the gravity dual. Fine tuning in the lattice theory is
avoided by the use of a lattice action with exact supersymmetry.Comment: 21 pages, 8 figures. v2: References added, two figures were modified
for clarity. v3: Normalisation of lattice coupling corrected by factor of two
resulting in change of estimate for c_cri
Tropical nighttime warming as a dominant driver of variability in the terrestrial carbon sink
The terrestrial biosphere is currently a strong carbon (C) sink but may switch to a source in the 21st century as climate-driven losses exceed CO2-driven C gains, thereby accelerating global warming. Although it has long been recognized that tropical climate plays a critical role in regulating interannual climate variability, the causal link between changes in temperature and precipitation and terrestrial processes remains uncertain. Here, we combine atmospheric mass balance, remote sensing-modeled datasets of vegetation C uptake, and climate datasets to characterize the temporal variability of the terrestrial C sink and determine the dominant climate drivers of this variability. We show that the interannual variability of global land C sink has grown by 50–100% over the past 50 y. We further find that interannual land C sink variability is most strongly linked to tropical nighttime warming, likely through respiration. This apparent sensitivity of respiration to nighttime temperatures, which are projected to increase faster than global average temperatures, suggests that C stored in tropical forests may be vulnerable to future warming
A cluster randomized controlled trial of the effectiveness and cost-effectiveness of Intermediate Care Clinics for Diabetes (ICCD) : study protocol for a randomized controlled trial
Background
World-wide healthcare systems are faced with an epidemic of type 2 diabetes. In the United Kingdom, clinical care is primarily provided by general practitioners (GPs) rather than hospital specialists. Intermediate care clinics for diabetes (ICCD) potentially provide a model for supporting GPs in their care of people with poorly controlled type 2 diabetes and in their management of cardiovascular risk factors. This study aims to (1) compare patients with type 2 diabetes registered with practices that have access to an ICCD service with those that have access only to usual hospital care; (2) assess the cost-effectiveness of the intervention; and (3) explore the views and experiences of patients, health professionals and other stakeholders.
Methods/Design
This two-arm cluster randomized controlled trial (with integral economic evaluation and qualitative study) is set in general practices in three UK Primary Care Trusts. Practices are randomized to one of two groups with patients referred to either an ICCD (intervention) or to hospital care (control).
Intervention group: GP practices in the intervention arm have the opportunity to refer patients to an ICCD - a multidisciplinary team led by a specialist nurse and a diabetologist. Patients are reviewed and managed in the ICCD for a short period with a goal of improving diabetes and cardiovascular risk factor control and are then referred back to practice.
or
Control group: Standard GP care, with referral to secondary care as required, but no access to ICCD.
Participants are adults aged 18 years or older who have type 2 diabetes that is difficult for their GPs to control. The primary outcome is the proportion of participants reaching three risk factor targets: HbA1c (≤7.0%); blood pressure (<140/80); and cholesterol (<4 mmol/l), at the end of the 18-month intervention period. The main secondary outcomes are the proportion of participants reaching individual risk factor targets and the overall 10-year risks for coronary heart disease(CHD) and stroke assessed by the United Kingdom Prospective Diabetes Study (UKPDS) risk engine. Other secondary outcomes include body mass index and waist circumference, use of medication, reported smoking, emotional adjustment, patient satisfaction and views on continuity, costs and health related quality of life. We aimed to randomize 50 practices and recruit 2,555 patients
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