scholarly journals A forth-and-back implicit λ iteration in the solution of radiative transfer in spherical media

2003 ◽  
pp. 27-34 ◽  
Author(s):  
Olga Atanackovic-Vukmanovic
Keyword(s):  
Radiative Transfer ◽  
Efficient Method ◽  
Spherical Symmetry ◽  
Source Function ◽  
The Other ◽  
Implicit Representation ◽  
The Mean ◽  
Parallel Geometry ◽  
Transfer Problems ◽  
Implicit Iteration

Forth-and-back implicit ?-iteration has been developed to solve radiative transfer (RT) problems with plane-parallel geometry in which there is a coupling of all RT equations by the scattering term included in the source function (Atanackovic-Vukmanovic, Crivellari and Simonneau 1997). Owing to the implicit representation of the source function in the computation of the mean intensities within a forth-and-back sequential treatment of the two intensities propagating in opposite directions, implicit ?-iteration (ILI) appears to be a very efficient method in the solution of linear as well as non-linear transfer problems. In this paper ILI method is generalized and applied to radiative transfer problems with spherical symmetry. The results for the monochromatic radiative transfer in a spherical atmosphere are presented and compared to those of other authors obtained by the other methods.

scholarly journals Dynamical Instabilities in Spherical Stellar Systems

1985 ◽  
Vol 113 ◽  
pp. 297-299
Author(s):  
Joshua Barnes
Keyword(s):  
Mass Distribution ◽  
Spherical Symmetry ◽  
Mean Field ◽  
The Other ◽  
Stellar Systems ◽  
Spherically Symmetric ◽  
Quadrupole Mode ◽  
Radial Forces ◽  
The Mean ◽  
Dynamical Instabilities

Equlibrium spherical stellar systems exhibiting instabilities on a dynamical timescale were first studied by Henon (1973), using a spherically symmetric N-body code. We have re-examined Henon's models using an improved code which includes non-radial forces to quadrupole order. In addition to the radial instability reported by Henon, two new non-radial instabilities are also observed. In one, found in models with highly circular orbits, the mass distribution exhibits quadrupole-mode oscillations. In the other, seen in models with highly radial orbits, the system spontaneously breaks spherical symmetry and settles into a tri-axial ellipsoid. These instabilities, which are driven by fluctuations of the mean field, offer some analogies to the well-known dynamical instabilities of a cold disk of stars. While our models are rather artificial, they indicate that dynamical instabilities may be more common in spherical systems than had been thought.

scholarly journals Promoting Hand Sanitizer Use in a University Cafeteria

2020 ◽  
Vol 29 (1) ◽  
pp. 255-263 ◽  
Author(s):  
Christoph Bördlein
Keyword(s):  
Efficient Method ◽  
Control Site ◽  
The Other ◽  
Response Effort ◽  
Public Places ◽  
Hand Sanitizer ◽  
Considerable Impact ◽  
The Mean ◽  
Cost Efficient

AbstractHandwashing is the most cost-efficient method to lower the risk of the transmission of infectious diseases. Especially before eating in public places like cafeterias, handwashing is recommended. Often, people do not wash their hands before eating because of the response effort associated with going to the bathroom. As an alternative way to improve hygiene, disinfection with a hand sanitizer gel is recommended. The current study used an A-B-C-A design (and a no-intervention control site) with prompts and feedback to increase the number of cafeteria patrons using hand sanitizer. Dispensers for hand sanitizer gel were placed at the entrance area of two halls of a university cafeteria. Intervention took place in one hall, whereas the other served as a control. After baseline, a poster explaining the usefulness of hand sanitizing was posted near the entrance of the cafeteria. This led to a doubling of the percentage of cafeteria patrons using the hand sanitizer, from 10.79% during baseline to 24.45%. A second poster provided feedback about the percentage of patrons sanitizing their hands and asked for more participation. This led to no further increases in hand sanitizing (23.73%). After all posters were removed, the percentage dropped to 15.63% in the mean. This research demonstrated that a simple, informative prompt can have a considerable impact on hand-sanitizing behavior. However, the role of feedback in such interventions remains questionable.

Multi-Center Study of Thromboplastin Calibration Precision – Influence of Reagent Species, Composition, and International Sensitivity Index (ISI)

1993 ◽  
Vol 69 (01) ◽  
pp. 035-040 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Oral Anticoagulants ◽  
International Normalized Ratio ◽  
The Other ◽  
World Health ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Bovine Plasma ◽  
Significant Difference ◽  
The Mean ◽  
International Sensitivity Index

SummaryFour thromboplastin reagents were tested by 18 laboratories in Europe, North-America, and Australasia, according to a detailed protocol. One thromboplastin was the International Reference Preparation for ox brain thromboplastin combined with adsorbed bovine plasma (coded OBT/79), and the second was a certified reference material for rabbit brain thromboplastin, plain (coded CRM 149R). The other two thromboplastin reagents were another rabbit plain brain thromboplastin (RP) with a lower ISI than CRM 149R and a rabbit brain thromboplastin combined with adsorbed bovine plasma (RC). Calibration of the latter two reagents was performed according to methods recommended by the World Health Organization (W. H. O.).The purpose of this study was to answer the following questions: 1) Is the calibration of the RC reagent more precise against the bovine/combined (OBT/79) than against the rabbit/plain reagent (CRM 149R)? 2) Is the precision of calibration influenced by the magnitude of the International Sensitivity Index (ISI)?The lowest inter-laboratory variation of ISI was observed in the calibration of the rabbit/plain reagent (RP) against the other rabbit/plain reagent (CRM 149R) (CV 1.6%). The highest interlaboratory variation was obtained in the calibration of rabbit/plain (RP) against bovine/combined (OBT/79) (CV 5.1%). In the calibration of the rabbit/combined (RC) reagent, there was no difference in precision between OBT/79 (CV 4.3%) and CRM 149R (CV 4.2%). Furthermore, there was no significant difference in the precision of the ISI of RC obtained with CRM 149R (ISI = 1.343) and the rabbit/plain (RP) reagent with ISI = 1.14. In conclusion, the calibration of RC could be performed with similar precision with either OBT/79 or CRM 149R, or RP.The mean ISI values calculated with OBT/79 and CRM 149R were practically identical, indicating that there is no bias in the ISI of these reference preparations and that these reference preparations have been stable since their original calibration studies in 1979 and 1987, respectively.International Normalized Ratio (INR) equivalents were calculated for a lyophilized control plasma derived from patients treated with oral anticoagulants. There were small but significant differences in the mean INR equivalents between the bovine and rabbit thromboplastins. There were no differences in the interlaboratory variation of the INR equivalents, when the four thromboplastins were compared.

Prothrombin Time Standardization: Report of the Expert Panel on Oral Anticoagulant Control

1979 ◽  
Vol 42 (04) ◽  
pp. 1073-1114 ◽  
Keyword(s):  
Prothrombin Time ◽  
Expert Panel ◽  
The Other ◽  
Rabbit Brain ◽  
Calibration Constant ◽  
Freeze Dried ◽  
The Mean ◽  
Point Of Intersection ◽  
And Control ◽  
Standardization Report

SummaryIn collaborative experiments in 199 laboratories, nine commercial thromboplastins, four thromboplastins held by the National Institute for Biological Standards and Control (NIBS & C), London and the British Comparative Thromboplastin were tested on fresh normal and coumarin plasmas, and on three series of freeze-dried plasmas. One of these was made from coumarin plasmas and the other two were prepared from normal plasmas; in each series, one plasma was normal and the other two represented different degrees of coumarin defect.Each thromboplastin was calibrated against NIBS&C rabbit brain 70/178, from the slope of the line joining the origin to the point of intersection of the mean ratios of coumarin/normal prothrombin times when the ratios obtained with the two thromboplastins on the same fresh plasmas were plotted against each other. From previous evidence, the slopes were calculated which would have been obtained against the NIBS&C “research standard” thromboplastin 67/40, and termed the “calibration constant” of each thromboplastin. Values obtained from the freeze-dried coumarin plasmas gave generally similar results to those from fresh plasmas for all thromboplastins, whereas values from the artificial plasmas agreed with those from fresh plasmas only when similar thromboplastins were being compared.Taking into account the slopes of the calibration lines and the variation between laboratories, precision in obtaining a patient’s prothrombin time was similar for all thromboplastins.

Platelet Suruival and Function in Rats with Enhanced Thrombotic Tendency

1985 ◽  
Vol 54 (04) ◽  
pp. 739-743 ◽  
Author(s):  
Federica Delaini ◽  
Elisabetta Dejana ◽  
Ine Reyers ◽  
Elisa Vicenzi ◽  
Germana De Bellis Vitti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Nephrotic Syndrome ◽  
Platelet Function ◽  
Laboratory Tests ◽  
Thrombus Formation ◽  
The Other ◽  
Mean Survival Time ◽  
The Mean ◽  
And Function ◽  
Thrombotic Tendency

SummaryWe have investigated the relevance of some laboratory tests of platelet function in predicting conditions of thrombotic tendency. For this purpose, we studied platelet survival, platelet aggregation in response to different stimuli, TxB2 and 6-keto-PGFlα production in serum of rats bearing a nephrotic syndrome induced by adriamycin. These animals show a heavy predisposition to the development of both arterial and venous thrombosis. The mean survival time was normal in nephrotic rats in comparison to controls. As to aggregation tests, a lower aggregating response was found in ADR-treated rats using ADP or collagen as stimulating agents. With arachidonic acid (AA) we observed similar aggregating responses at lower A A concentrations, whereas at higher AA concentrations a significantly lower response was found in nephrotic rats, despite their higher TxB2 production. Also TxB2 and 6-keto-PGFlα levels in serum of nephrotic rats were significantly higher than in controls. No consistent differences were found in PGI2-activity generated by vessels of control or nephrotic rats.These data show that platelet function may appear normal or even impaired in rats with a markedly increased thrombotic tendency. On the other hand, the significance of high TxB2 levels in connection with mechanisms leading to thrombus formation remains a controversial issue.

Voronoi Analysis of a Soccer Game

2004 ◽  
Vol 9 (3) ◽  
pp. 233-240 ◽  
Author(s):  
S. Kim
Keyword(s):  
Collective Behavior ◽  
Quantitative Assessment ◽  
The Other ◽  
Analysis Method ◽  
Random System ◽  
Soccer Game ◽  
Voronoi Polygons ◽  
The Mean

This paper describes a Voronoi analysis method to analyze a soccer game. It is important for us to know the quantitative assessment of contribution done by a player or a team in the game as an individual or collective behavior. The mean numbers of vertices are reported to be 5–6, which is a little less than those of a perfect random system. Voronoi polygons areas can be used in evaluating the dominance of a team over the other. By introducing an excess Voronoi area, we can draw some fruitful results to appraise a player or a team rather quantitatively.

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