1,648 research outputs found
Dulling a Needle: Analyzing Federal Employment Restrictions on People with Insulin-Dependent Diabetes
Measurement of Photon Statistics with Live Photoreceptor Cells
We analyzed the electrophysiological response of an isolated rod
photoreceptor of Xenopus laevis under stimulation by coherent and
pseudo-thermal light sources. Using the suction electrode technique for single
cell recordings and a fiber optics setup for light delivery allowed
measurements of the major statistical characteristics of the rod response. The
results indicate differences in average responses of rod cells to coherent and
pseudo-thermal light of the same intensity and also differences in
signal-to-noise ratios and second order intensity correlation functions. These
findings should be relevant for interdisciplinary studies seeking applications
of quantum optics in biology.Comment: 6 pages, 7 figure
Recoverin Regulates Light-dependent Phosphodiesterase Activity in Retinal Rods
The Ca2+-binding protein recoverin may regulate visual transduction in retinal rods and cones, but its functional role and mechanism of action remain controversial. We compared the photoresponses of rods from control mice and from mice in which the recoverin gene was knocked out. Our analysis indicates that Ca2+-recoverin prolongs the dark-adapted flash response and increases the rod's sensitivity to dim steady light. Knockout rods had faster Ca2+ dynamics, indicating that recoverin is a significant Ca2+ buffer in the outer segment, but incorporation of exogenous buffer did not restore wild-type behavior. We infer that Ca2+-recoverin potentiates light-triggered phosphodiesterase activity, probably by effectively prolonging the catalytic activity of photoexcited rhodopsin
Developmental Evaluation in Theory versus Practice: Lessons from Three Developmental Evaluation Pilots
Background. Developmental Evaluation (DE) practitioners turn to DE theory to make design and implementation decisions. However, DE practitioners can experience difficulty in fully understanding how to implement DE using theory because it is method agnostic (Patton, 2016). Instead, DE is a principle-based approach.
Purpose. This article presents an empirical examination of how DE theory was (or was not) applied during three DE pilots. Our analysis aims to better understand how DE theory is used in practice to expand the evidence base and strengthen future DE implementation.
Setting. A consortium of three organizations implemented three DE pilots through the United States Agency for International Development (USAID) from November 2016 to September 2019. The authors—who participated in the consortium—did not implement the DEs but instead conducted a study or meta-evaluation across the DE pilots.
Data Collection and Analysis. This article focuses on the results of an ex post facto analysis of three DE pilots based on the entire DE implementation experience. For each DE studied, we used mixed methods to collect data on the effectiveness of the DE approach, to identify adaptations to strengthen DE implementation in the USAID context, and to measure its value to stakeholders. Data included more than 100 hours of interviews, 465 pages of qualitative data, and 30 surveys completed by DE participants.
Findings. We find that the ability to apply the DE principles in practice is influenced, in no particular order, by DE participant buy-in to the DE, the Developmental Evaluator’s aptitude, support and resources available to the Developmental Evaluator, and the number of DE participants. We also find that buy-in can change and this should be closely monitored throughout a DE to inform whether a DE should be paused or prematurely ended.
Keywords: Developmental Evaluation; developmental evaluator skills; buy-in; DE practice; DE funder; meta-evaluatio
Analysis of D Pellet Injection Experiments in the W7-AS Stellarator
A centrifugal injector was used to inject deuterium pellets (with 3--5 x 10{sup 19} atoms) at approx. equal 600 m/s into current-less, nearly shear-less plasmas in the Wendelstein 7-AS (W7-AS) stellarator. The D pellet was injected horizontally at a location where the non-circular and non-axisymmetric plasma cross section is nearly triangular. Visible-light TV pictures usually showed the pellet as a single ablating mass in the plasma, although the pellet occasionally broke in two or splintered into a cloud of small particles. The density evolution following pellet injection and the effect of pellet injection on energy confinement and fluctuations are discussed
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Development of novel Sol-Gel Indicators (SGI`s) for in-situ environmental measurements: Part 1, Program and a new pH Sol-Gel Indicator
The feasibility of incorporating analytical indicators into a sol-gel glassy matrix and then coating substrates with this composite material has bee demonstrated. Substrates coated include paper, wood, glass, and the lens of an analytical probe. The first SRTC sol-gel indicator, comprising bromophenol blue dispersed in a silica matrix, was fabricated and successfully used to measure solution pH in the range of pH 3.0 to 7.5. material exhibited a quick response time, as measured by color changes both qualitatively and quantitatively, and the measuring device was reversible or reusable. Additional indicators with responses over other ranges as well as indicators sensitive to the presence of elements of interest, are also under development. The new SGI composites possess promising properties and an excellent potential for performing a variety important in-situ environmental measurements and area discussed in this report
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