34 research outputs found
A Model for the Stray Light Contamination of the UVCS Instrument on SOHO
We present a detailed model of stray-light suppression in the spectrometer
channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO
spacecraft. The control of diffracted and scattered stray light from the bright
solar disk is one of the most important tasks of a coronagraph. We compute the
fractions of light that diffract past the UVCS external occulter and
non-specularly pass into the spectrometer slit. The diffracted component of the
stray light depends on the finite aperture of the primary mirror and on its
figure. The amount of non-specular scattering depends mainly on the
micro-roughness of the mirror. For reasonable choices of these quantities, the
modeled stray-light fraction agrees well with measurements of stray light made
both in the laboratory and during the UVCS mission. The models were constructed
for the bright H I Lyman alpha emission line, but they are applicable to other
spectral lines as well.Comment: 19 pages, 5 figures, Solar Physics, in pres
Prominence-cavity regions observed using SWAP 174A filtergrams and simultaneous eclipse flash spectra
Images from the SWAP (Proba 2 mission) taken at 174A in the Fe IX/X lines are
compared to simultaneous slitless flash spectra taken during the last solar
total eclipse of July, 11th 2010. Many faint low excitation emission lines
together with the HeI and HeII Paschen Alpha chromospheric lines are recorded
on eclipse spectra where regions of limb prominences are obtained with
space-borne imagers. We consider a deep flash spectrum obtained by summing 80
individual spectra to show the intensity modulations of the continuum.
Intensity depressions are observed around the prominences in both eclipse and
SWAP images. The prominence cavities are interpreted as a relative depression
of plasma density, produced inside the corona surrounding the prominences.
Photometric measurements are shown at different scales and different,
spectrally narrow, intervals for both the prominences and the coronal
background.Comment: 22 pages, 14 figures, accepted to publish in Sol. Phy
The Physical Processes of CME/ICME Evolution
As observed in Thomson-scattered white light, coronal mass ejections (CMEs) are manifest as large-scale expulsions of plasma magnetically driven from the corona in the most energetic eruptions from the Sun. It remains a tantalizing mystery as to how these erupting magnetic fields evolve to form the complex structures we observe in the solar wind at Earth. Here, we strive to provide a fresh perspective on the post-eruption and interplanetary evolution of CMEs, focusing on the physical processes that define the many complex interactions of the ejected plasma with its surroundings as it departs the corona and propagates through the heliosphere. We summarize the ways CMEs and their interplanetary CMEs (ICMEs) are rotated, reconfigured, deformed, deflected, decelerated and disguised during their journey through the solar wind. This study then leads to consideration of how structures originating in coronal eruptions can be connected to their far removed interplanetary counterparts. Given that ICMEs are the drivers of most geomagnetic storms (and the sole driver of extreme storms), this work provides a guide to the processes that must be considered in making space weather forecasts from remote observations of the corona.Peer reviewe
Safety and efficacy of vanzacaftorâtezacaftorâdeutivacaftor in adults with cystic fibrosis: randomised, double-blind, controlled, phase 2 trials
Background
Elexacaftorâtezacaftorâivacaftor has been shown to be safe and efficacious in people with cystic fibrosis and at least one F508del allele. Our aim was to identify a novel cystic fibrosis transmembrane conductance regulator (CFTR) modulator combination capable of further increasing CFTR-mediated chloride transport, with the potential for once-daily dosing.
Methods
We conducted two phase 2 clinical trials to assess the safety and efficacy of a once-daily combination of vanzacaftorâtezacaftorâdeutivacaftor in participants with cystic fibrosis who were aged 18 years or older. A phase 2 randomised, double-blind, active-controlled study (VX18-561-101; April 17, 2019, to Aug 20, 2020) was carried out to compare deutivacaftor monotherapy with ivacaftor monotherapy in participants with CFTR gating mutations, following a 4-week ivacaftor monotherapy run-in period. Participants were randomly assigned to receive either ivacaftor 150 mg every 12 h, deutivacaftor 25 mg once daily, deutivacaftor 50 mg once daily, deutivacaftor 150 mg once daily, or deutivacaftor 250 mg once daily in a 1:1:2:2:2 ratio. The primary endpoint was absolute change in ppFEV1 from baseline at week 12. A phase 2 randomised, double-blind, controlled, proof-of-concept study of vanzacaftorâtezacaftorâdeutivacaftor (VX18-121-101; April 30, 2019, to Dec 10, 2019) was conducted in participants with cystic fibrosis and heterozygous for F508del and a minimal function mutation (F/MF genotypes) or homozygous for F508del (F/F genotype). Participants with F/MF genotypes were randomly assigned 1:2:2:1 to receive either 5 mg, 10 mg, or 20 mg of vanzacaftor in combination with tezacaftorâdeutivacaftor or a triple placebo for 4 weeks, and participants with the F/F genotype were randomly assigned 2:1 to receive either vanzacaftor (20 mg)âtezacaftorâdeutivacaftor or tezacaftorâivacaftor active control for 4 weeks, following a 4-week tezacaftorâivacaftor run-in period. Primary endpoints for part 1 and part 2 were safety and tolerability and absolute change in ppFEV1 from baseline to day 29. Secondary efficacy endpoints were absolute change from baseline at day 29 in sweat chloride concentrations and Cystic Fibrosis Questionnaire-Revised (CFQ-R) respiratory domain score. These clinical trials are registered with ClinicalTrials.gov, NCT03911713 and NCT03912233, and are complete.
Findings
In study VX18-561-101, participants treated with deutivacaftor 150 mg once daily (n=23) or deutivacaftor 250 mg once daily (n=24) had mean absolute changes in ppFEV1 of 3·1 percentage points (95% CI â0·8 to 7·0) and 2·7 percentage points (â1·0 to 6·5) from baseline at week 12, respectively, versus â0·8 percentage points (â6·2 to 4·7) with ivacaftor 150 mg every 12 h (n=11); the deutivacaftor safety profile was consistent with the established safety profile of ivacaftor 150 mg every 12 h. In study VX18-121-101, participants with F/MF genotypes treated with vanzacaftor (5 mg)âtezacaftorâdeutivacaftor (n=9), vanzacaftor (10 mg)âtezacaftorâdeutivacaftor (n=19), vanzacaftor (20 mg)âtezacaftorâdeutivacaftor (n=20), and placebo (n=10) had mean changes relative to baseline at day 29 in ppFEV1 of 4·6 percentage points (â1·3 to 10·6), 14·2 percentage points (10·0 to 18·4), 9·8 percentage points (5·7 to 13·8), and 1·9 percentage points (â4·1 to 8·0), respectively, in sweat chloride concentration of â42·8 mmol/L (â51·7 to â34·0), â45·8 mmol/L (95% CI â51·9 to â39·7), â49·5 mmol/L (â55·9 to â43·1), and 2·3 mmol/L (â7·0 to 11·6), respectively, and in CFQ-R respiratory domain score of 17·6 points (3·5 to 31·6), 21·2 points (11·9 to 30·6), 29·8 points (21·0 to 38·7), and 3·3 points (â10·1 to 16·6), respectively. Participants with the F/F genotype treated with vanzacaftor (20 mg)âtezacaftorâdeutivacaftor (n=18) and tezacaftorâivacaftor (n=10) had mean changes relative to baseline (taking tezacaftorâivacaftor) at day 29 in ppFEV1 of 15·9 percentage points (11·3 to 20·6) and â0·1 percentage points (â6·4 to 6·1), respectively, in sweat chloride concentration of â45·5 mmol/L (â49·7 to â41·3) and â2·6 mmol/L (â8·2 to 3·1), respectively, and in CFQ-R respiratory domain score of 19·4 points (95% CI 10·5 to 28·3) and â5·0 points (â16·9 to 7·0), respectively. The most common adverse events overall were cough, increased sputum, and headache. One participant in the vanzacaftorâtezacaftorâdeutivacaftor group had a serious adverse event of infective pulmonary exacerbation and another participant had a serious rash event that led to treatment discontinuation. For most participants, adverse events were mild or moderate in severity.
Interpretation
Once-daily dosing with vanzacaftorâtezacaftorâdeutivacaftor was safe and well tolerated and improved lung function, respiratory symptoms, and CFTR function. These results support the continued investigation of vanzacaftorâtezacaftorâdeutivacaftor in phase 3 clinical trials compared with elexacaftorâtezacaftorâivacaftor.
Funding
Vertex Pharmaceuticals
Similarity-based retrieval and solution re-use policies in the game of Texas holdâem, in: Case-Based Reasoning
Abstract. In previous papers we have presented our autonomous poker playing agent (SARTRE) that uses a memory-based approach to create a betting strategy for two-player, limit Texas Holdâem. SARTRE participated in the 2009 IJCAI Computer Poker Competition where the system was thoroughly evaluated by challenging a range of other computerised opponents. Since the competition SARTRE has undergone case-based maintenance. In this paper we present results from the 2009 Computer Poker Competition and describe the latest modifications and improvements to the system. Specifically, we investigate two claims: the first that modifying the solution representation results in changes to the problem coverage and the second that different policies for re-using solutions leads to changes in performance. Three separate solution re-use policies for making betting decisions are introduced and evaluated. We conclude by presenting results of self-play experiments between the pre and post maintenance systems.
Educating for anti-racism: producing and reproducing race and power in a university classroom
In this paper I explore some of the issues associated with teaching about race, culture and ethnicity in a psychology program. These curriculum initiatives are part of a broader agenda of raising awareness about racialised oppression and exclusion and contributing to the development of ways of researching and practising psychology that are transformative and culturally sensitive. I overview the broader context and describe our subject and the guiding principles. This is followed by a description and analysis of two events in the classroom that illustrate the ways in which students differentially respond to the challenges posed by writings that challenge taken for granted understandings of race. Part of the analysis shows that students can often engage in the reproduction of oppressive practices and invest in whiteness. It is suggested that more than single semester subjects are required to promote and support the development of critical capacities for anti-racism practice