222 research outputs found
Lichen Deterioration About a Coal-Fired Steam Electric Generating Plant
A survey of three common epiphytic species of foliose lichens was conducted about a coal-fired steam electric station in North-central Minnesota during the summer of 1977 to assess general lichen health on a gradient basis from a point-source of air pollution. Health, as judged by abnormal form and color, of nearly 3,500 lichen specimens was recorded in 35 vegetation survey plots from a total of 291 trees. Lichen discoloration and degeneration decreased with increased distance from the power plant, and little deterioration was observed beyond 3 miles. Within the plant vicinity, lichen damage was noted on tree boles facing the plant which were impacted with fly ash. Maximum damage of lichens followed the pattern of prevailing winds (NW-SE). Sulfur analysis of lichen thalli was not correlated with visible damage distribution tended to decrease at the most distant plots (30 mi. from source).
Considering the sensitivity of foliose lichens to declining air quality (especially S02 pollution), pollution sources in the rural environment are bound to affect lichen communities, as this study indicates. More sophisticated lichen surveys coupled with future monitoring of pollution would be a valuable contribution to the general environmental impact assessment of coal-fired electrical energy production
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
Early precipitated micropyrite in microbialites: A time capsule of microbial sulfur cycling
Microbialites are organosedimentary rocks that have occurred throughout the Earth’s
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 δ34S values1. Considering
the sulfate-sulfur isotopic compositions associated with both environments, micropyrites display a remarkably narrow range
of Δpyr (i.e. Δpyr ≡ δ34SSO4 − δ34Spyr) between 56 and 62‰. These measured Δpyr 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
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 Rabat–Khenifra 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 20–25 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 200–300 km in the north-western limb of the Western Moroccan Meseta
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
Recommended from our members
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
Tempered mlo broad-spectrum resistance to barley powdery mildew in an Ethiopian landrace
Recessive mutations in the Mlo gene confer broad spectrum resistance in barley (Hordeum vulgare) to powdery mildew (Blumeria graminis f. sp. hordei), a widespread and damaging disease. However, all alleles discovered to date also display deleterious pleiotropic effects, including the naturally occurring mlo-11 mutant which is widely deployed in Europe. Recessive resistance was discovered in Eth295, an Ethiopian landrace, which was developmentally controlled and quantitative without spontaneous cell wall appositions or extensive necrosis and loss of photosynthetic tissue. This resistance is determined by two copies of the mlo-11 repeat units, that occur upstream to the wild-type Mlo gene, compared to 11-12 in commonly grown cultivars and was designated mlo-11 (cnv2). mlo-11 repeat unit copy number-dependent DNA methylation corresponded with cytological and macroscopic phenotypic differences between copy number variants. Sequence data indicated mlo-11 (cnv2) formed via recombination between progenitor mlo-11 repeat units and the 3' end of an adjacent stowaway MITE containing region. mlo-11 (cnv2) is the only example of a moderated mlo variant discovered to date and may have arisen by natural selection against the deleterious effects of the progenitor mlo-11 repeat unit configuration
Cation Exchange in Smectites as a New Approach to Mineral Carbonation
Mineral carbonation of alkaline mine residues is a carbon dioxide removal (CDR) strategy that can be employed by the mining industry. Here, we describe the mineralogy and reactivity of processed kimberlites and kimberlite ore from Venetia (South Africa) and Gahcho Kué (Canada) diamond mines, which are smectite-rich (2.3–44.1 wt.%). Whereas, serpentines, olivines, hydrotalcites and brucite have been traditionally used for mineral carbonation, little is known about the reactivity of smectites to CO2. The smectite from both mines is distributed as a fine-matrix and is saponite, Mx/mm+Mg3(AlxSi4−x)O10(OH)2·nH2O, where the layer charge deficiency is balanced by labile, hydrated interlayer cations (Mm+). A positive correlation between cation exchange capacity and saponite content indicates that smectite is the most reactive phase within these ultramafic rocks and that it can be used as a source of labile Mg2+ and Ca2+ for carbonation reactions. Our work shows that smectites provide the fast reactivity of kimberlite to CO2 in the absence of the highly reactive mineral brucite [Mg(OH)2]. It opens up the possibility of using other, previously inaccessible rock types for mineral carbonation including tailings from smectite-rich sediment-hosted metal deposits and oil sands tailings. We present a decision tree for accelerated mineral carbonation at mines based on this revised understanding of mineralogical controls on carbonation potential
- …