252 research outputs found
Compact 20-pass thin-disk amplifier insensitive to thermal lensing
We present a multi-pass amplifier which passively compensates for distortions
of the spherical phase front occurring in the active medium. The design is
based on the Fourier transform propagation which makes the output beam
parameters insensitive to variation of thermal lens effects in the active
medium. The realized system allows for 20 reflections on the active medium and
delivers a small signal gain of 30 with M = 1.16. Its novel geometry
combining Fourier transform propagations with 4f-imaging stages as well as a
compact array of adjustable mirrors allows for a layout with a footprint of 400
mm x 1000 mm.Comment: 7 pages, 6 figure
Status and perspectives of SARNET network
43 organisations (research, universities, industry, utilities, safety authorities and TSO) from 22 countries network their capabilities for R&D on
Severe Accidents (SA) in SARNET (Severe Accident Research NETwork of excellence) in the EC FP7 for 4 years from April 2009. The overall work
represents about 40 persons per year (230 researchers and 20 PhD students). A 43rd partner is currently joining the network: BARC (India).
See www.sar-net.e
Proposed relation between SARNET network on severe accidents and TWG Gen.II/III
SA Research Priorities defined in SARNET network should be the basis for proposing in the future relevant R&D programs to address them, when needed, and launch
projects with the endorsement of TWG
Transgenic wheat expressing a barley class II chitinase gene has enhanced resistance against Fusarium graminearum
Fusarium head blight (FHB; scab), primarily caused by Fusarium graminearum, is a devastating disease of wheat worldwide. FHB causes yield reductions and contamination of grains with trichothecene mycotoxins such as deoxynivalenol (DON). The genetic variation in existing wheat germplasm pools for FHB resistance is low and may not provide sufficient resistance to develop cultivars through traditional breeding approaches. Thus, genetic engineering provides an additional approach to enhance FHB resistance. The objectives of this study were to develop transgenic wheat expressing a barley class II chitinase and to test the transgenic lines against F. graminearum infection under greenhouse and field conditions. A barley class II chitinase gene was introduced into the spring wheat cultivar, Bobwhite, by biolistic bombardment. Seven transgenic lines were identified that expressed the chitinase transgene and exhibited enhanced Type II resistance in the greenhouse evaluations. These seven transgenic lines were tested under field conditions for percentage FHB severity, percentage visually scabby kernels (VSK), and DON accumulation. Two lines (C8 and C17) that exhibited high chitinase protein levels also showed reduced FHB severity and VSK compared to Bobwhite. One of the lines (C8) also exhibited reduced DON concentration compared with Bobwhite. These results showed that transgenic wheat expressing a barley class II chitinase exhibited enhanced resistance against F. graminearum in greenhouse and field conditions
Early precipitated micropyrite in microbialites: A time capsule of microbial sulfur cycling
Microbialites are organosedimentary rocks that have occurred throughout the Earthâs
history. The relationships between diverse microbial metabolic activities and isotopic
signatures in biominerals forming within these microbialites are key to understanding
modern biogeochemical cycles, but also for accurate interpretation of the geologic
record. Here, we performed detailed mineralogical investigations coupled with
NanoSIMS (Nanoscale Secondary Ion Mass Spectrometry) analyses of pyrite S
isotopes in mineralising microbial mats from two different environments, a hypersaline
lagoon (Cayo Coco, Cuba) and a volcanic alkaline crater lake (Atexcac, Mexico).
Both microbialite samples contain two distinct pyrite morphologies: framboids and
euhedral micropyrites, which display distinct ranges of ÎŽ34S values1. Considering
the sulfate-sulfur isotopic compositions associated with both environments, micropyrites display a remarkably narrow range
of Îpyr (i.e. Îpyr ⥠Ύ34SSO4 â ÎŽ34Spyr) between 56 and 62â°. These measured Îpyr values agree with sulfate-sulfide equilibrium
fractionation, as observed in natural settings characterised by low microbial sulfate reduction respiration rates. Moreover, the
distribution of S isotope compositions recorded in the studied micropyrites suggests that sulfide oxidation also occurred at
the microbialite scale. These results highlight the potential of micropyrites to capture signatures of microbial sulfur cycling
and show that S isotope composition in pyrites record primarily the local micro-environments induced by the microbialite
Franchising as a Strategy for Combining Small and Large Group Advantages (Logics) in Social Entrepreneurship:A Hayekian Perspective
This article develops a Hayekian perspective on social franchising that distinguishes between the end-connected logic of the small group and the rule-connected logic of the big group. Our key claim is that mission-driven social entrepreneurs often draw on the small-group logic when starting their social ventures and then face difficulties when the process of scaling shifts their operations toward a big-group logic. In this situation, social franchising offers a strategy to replicate the small group despite systemwide scaling, to mobilize decentrally accessible social capital, and to reduce agency costs through mechanisms of self-selection and self-monitoring. By employing a Hayekian perspective, we are thus able to offer an explanation as to why social franchising is a suitable scaling strategy for some social entrepreneurship organizations and not for others. We illustrate our work using the Ashoka Fellow Wellcome
Evidence for surface uplift of the Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleozoic basement)
This work represents an initial attempt to link the evolution of the topography in relation to the general tectonic framework of western Morocco. For this purpose, in a section of the Western Moroccan Meseta different tools are combined in order to attain the general objective. Apatite fission-track (AFT) data of granitic rocks of the RabatâKhenifra area give ages around 200 Ma with track length distributions which are compatible with the thermal models already established for the area. An inverse correlation between AFT ages and elevation is observed which is compatible with previous models indicating northward tilting of the whole Western Moroccan Meseta which is younger than 20â25 Ma. In order to test this possibility a detailed analysis of the topography at different scales in the Western Moroccan Meseta has been performed. Results indicate that two open folds with different amplitudes are recognized and that the one with wider wavelength could correspond to a lithospheric fold as previously stated by other authors on the basis of independent geological arguments. The northward tilting proposed based on the AFT data agrees with the results obtained in the analysis of the topography which reinforces the presence of a very open fold with a wavelength of 200â300 km in the north-western limb of the Western Moroccan Meseta
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Are Patient Self-Reported Outcome Measures Sensitive Enough to Be Used as End Points in Clinical Trials?: Evidence from the United Kingdom Glaucoma Treatment Study
Purpose
The United Kingdom Glaucoma Treatment Study (UKGTS) demonstrated the effectiveness of an intraocular pressure-lowering drug in patients with glaucoma using visual field progression as a primary outcome. The present study tested the hypothesis that responses on patient-reported outcome measures (PROMs; secondary outcome measure) differ between patients receiving a topical prostaglandin analog (latanoprost) or placebo eye drops in UKGTS.
Design
Multicenter, randomized, triple-masked, placebo-controlled trial.
Participants
Newly diagnosed glaucoma patients in the UKGTS with baseline and exit PROMs (n = 182 and n = 168 patients from the treatment and placebo groups, respectively).
Methods
In the UKGTS (trial registration number, ISRCTN96423140), patients with open-angle glaucoma were allocated to receive latanoprost (treatment) or placebo; the observation period was 24 months. Patients completed general health PROMs (European Quality of Life in 5 Dimensions [EQ-5D] and 36-item Short Form [SF-36]) and PROMs specific to glaucoma (15-item Glaucoma Quality of Life [GQL-15] and 9-item Glaucoma Activity Limitation [GAL-9]) at baseline and exit from the trial. Percentage changes between measurement on PROMs were calculated for each patient and compared between treatment arms. In addition, differences between stable patients (n = 272) and those with glaucomatous progression (n = 78), as determined by visual field change (primary outcome), were assessed.
Main Outcome Measure
PROMs on health-related and vision-related quality of life.
Results
Average percentage change on PROMs was similar for patients in both arms of the trial, with no statistically significant differences between treatment and placebo groups (EQ-5D, P = 0.98; EQ-5D visual analog scale, P = 0.88; SF-36, P = 0.94, GQL-15, P = 0.66; GAL-9, P = 0.87). There were statistically significant differences between stable and progressing patients on glaucoma-specific PROMs (GQL-15, P = 0.02; GAL-9, P = 0.02), but not on general health PROMs (EQ-5D, P = 0.62; EQ-5D visual analog scale, P = 0.23; SF-36, P = 0.65).
Conclusions
Average change in PROMs on health-related and vision-related quality of life was similar for the treatment and placebo groups in the UKGTS. The PROMs used may not be sensitive enough to function as primary end points in clinical trials when participants have newly diagnosed early-stage glaucoma
A Stewardship Cost Perspective on the Governance of Delegation Relationships:The Case of Social Franchising
We explore how nonprofits can effectively govern delegation relationships. We extend stewardship theory by conceptualizing stewardship costsâcosts in delegation relationships based on stewardship behavior. As stewards are theorized as other-regarding, self-actualizing, and intrinsically motivated, so far, literature almost exclusively points to the positive performance potential of stewardship behavior. Addressing this shortcoming, we develop propositions showing how stewardship selection costs rooted in the psychological characteristics of stewardship behavior and stewardship management costs rooted in situational factors of stewardship behavior occur during relationship formation and maintenance, and how they counteract the potential to increase performance. We identify and systematize opportunity costs of delayed growth, limited growth potential, and lost standardization gains, as well as increased selection and management costs. To demonstrate the theoretical potential and empirical relevance of our framework, we illustrate our arguments by referring to social franchising, a scaling strategy considered relevant for nonprofits as well as social enterprises
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