Improved solution of the lidar equation utilizing particle counter measurements

The extraction of particle backscattering from incoherent lidar measurements poses some problems. In the case of measurements of the stratospheric aerosol layer the solution of the lidar equation is based on two assumptions which are necessary to normalize the measured signal and to correct it with the two-way transmission of the laser pulse. Normalization and transmission are tackled by adding the information contained in aerosol particle counter measurements of the University of Wyoming to the ruby lidar measurements at Garmisch-Partenkirchen. Calculated backscattering from height levels above 25 km for the El Chichon period will be compared with lidar measurements and necessary corrections. The calculated backscatter-to-extinction ratios are compared to those, which were derived from a comparison of published extinction values to measured lidar backscattering at Garmisch. These ratios were used to calculate the Garmisch lidar returns. For the period 4 to 12 months after the El Chichon eruption a backscater-to-extinction ratio of 0.026 1/sr was applied with smaller values before and after that time

Three views of two degrees

Limiting global warming to 2°C above pre-industrial global mean temperature has become a widely endorsed goal for climate policy. It has also been severely criticized. We show how the limit emerged out of a marginal remark in an early paper about climate policy and distinguish three possible views of it. The catastrophe view sees it as the threshold separating a domain of safety from a domain of catastrophe. The cost-benefit view sees it as a strategy to optimize the relation between the costs and benefits of climate policy. The focal point view sees it as a solution to a complex coordination problem. We argue that the focal point view is the most appropriate. It leads to an emphasis on implementing effective steps toward a near-zero emissions economy, without panicking in the face of a possible temporary overshooting. After several decades of practical experiences, the focal point may or may not be redefined on the basis of knowledge gathered thanks to these experiences

Memory effects in vibrated granular systems

Granular materials present memory effects when submitted to tapping processes. These effects have been observed experimentally and are discussed here in the context of a general kind of model systems for compaction formulated at a mesoscopic level. The theoretical predictions qualitatively agree with the experimental results. As an example, a particular simple model is used for detailed calculations.Comment: 12 pages, 5 figures; to appear in Journal of Physics: Condensed Matter (Special Issue: Proceedings of ESF SPHINX Workshop on ``Glassy behaviour of kinetically constrained models.''

Sleep deprivation (SD) on focal brain ischemia in the rat : effects of different SD protocols

Sleep-wake disturbances are frequently observed in stroke patients and are associated with poorer functional outcome. Until now the effects of sleep on stroke evolution are unknown. The purpose of the present study was to evaluate the effects of three sleep deprivation (SD) protocols on brain damages after focal cerebral ischemia in a rat model. Permanent occlusion of distal branches of the middle cerebral artery was induced in adult rats. The animals were then subjected to 6h SD, 12h SD or sleep disturbances (SDis) in which 3 x 12h sleep deprivation were performed by gentle handling. Infarct size and brain swelling were assessed by Cresyl violet staining, and the number of damaged cells was measured by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining. Behavioral tests, namely tape removal and cylinder tests, were performed for assessing sensorimotor function. In the 6h SD protocol, no significant difference (P > 0.05) was found either in infarct size (42.5 ± 30.4 mm3 in sleep deprived animals vs. 44.5 ± 20.5 mm3 in controls, mean ± s.d.), in brain swelling (10.2 ± 3.8 % in sleep deprived animals vs. 11.3 ± 2.0 % in controls) or in number of TUNEL-positive cells (21.7 ± 2.0/mm2 in sleep deprived animals vs. 23.0 ± 1.1/mm2 in controls). In contrast, 12h sleep deprivation increased infarct size by 40 % (82.8 ± 10.9 mm3 in SD group vs. 59.2 ± 13.9 mm3 in control group, P = 0.008) and number of TUNEL-positive cells by 137 % (46.8 ± 15/mm in SD group vs. 19.7 ± 7.7/mm2 in control group, P = 0.003). There was no significant difference (P > 0.05) in brain swelling (12.9 ± 6.3 % in sleep deprived animals vs. 11.6 ± 6.0 % in controls). The SDis protocol also increased infarct size by 76 % (3 x 12h SD 58.8 ± 20.4 mm3 vs. no SD 33.8 ± 6.3 mm3, P = 0.017) and number of TUNEL-positive cells by 219 % (32.9 ± 13.2/mm2 vs. 10.3 ± 2.5/mm2, P = 0.008). Brain swelling did not show any difference between the two groups (24.5 ± 8.4 % in SD group vs. 16.7 ± 8.9 % in control group, p > 0.05). Both behavioral tests did not show any concluding results. In summary, we demonstrate that sleep deprivation aggravates brain damages in a rat model of stroke. Further experiments are needed to unveil the mechanisms underlying these effects

A study in the mathematical theory of the conduction of heat

This work represents a study in the application of the Laplace Trans format! on method to the Theory of Conduction of Heat; with a few exceptions indicated in footnotes, the derivation by this method of all the results is new. In Chapters II, VI, VIII, and X which contain collections of results, some of these are classical and given for completeness, and some are new* Almost all the results of Chapters I, III, IV, VII, and IX are believed to be new# None of this work has been submitted for any degree, and it is entirely my own with the exception of Chapters I and X, which have been written for publication in collaboration with Professor Carslaw. These are included here since they form an essential part of the whole scheme; the problems considered were solved independently and published jointly. The parts of this thesis which the referee may deem suitable will be published as soon as possible. Chapters I, VII, and X, and portion of Chapter I1/ have already been published, and Chapter III, and portions of Chapters VIII and IX are in the press# It is my pleasure to adknowledge my great indebtedness to Professor Carslaw who not only aroused my interest in the subject, but in the course of a frequent correspondence extending over several years has been most generous with advice and criticism# I am also indebted to Miss M. E. Clarke for her assistance with the computations of Chapter V and for the preparation of the typescript

Exploring dance: An outline for the study of dance appreciation with suggested films

Exploring Dance: An Outline for the Study of Dance Appreciation with Suggested Films surveys the history of the dance genres--ballet, ballroom, tap, and jazz--used in film musicals. Dance creators, their contributions to the art, as well as salient characteristics of each period are discussed. Each section concludes with an analysis of the function of dance in selected films; Chapter I outlines ballet\u27s history from the Renaissance through the twentieth century. The films Dancers, The Red Shoes, and Oklahoma! are examined. Chapter II chronicles ballroom dancing from the fourteenth to twentieth century. The Story of Vernon and Irene Castle is discussed. Chapter III traces the evolution of tap dance from the seventeenth to twentieth century. That\u27s Dancing is examined. Chapter IV outlines the growth of jazz dance from the early eighteenth century to the present and analyzes the function of jazz dance in West Side Story

The Effects Of Differential Reinforcement Structures On Computer-Assisted Instructional Learning

The use of computer assisted instruction as a viable educational technology in our nation\u27s schools has presented educators with new dilemmas and decisions. To operate these devices in the manner in which they were intended, computer software or courseware, whose cost often rivals the original cost of the computers themselves, must be purchased before their potential benefit can be realized. The most widely used type of instructional design that is inherent in these programs can be categorized under the operant theory of learning comprising the styles such as tutorial, skills building, and drill and practice. These computer lessons can be described as question-response-reinforcement in organizational design. The purpose of this study was to determine the nature of the reinforcement and its effects upon certain learner behaviors. Four computer lessons of equal length, scope and difficulty were designed to teach symbolic number systems to high school students. The lessons were designed with four different types of reinforcement structures ranging from sound and color graphics animation to simple knowledge of correct response. The programs were coded so that the students could control the real times allowed to read instructional frames, compute their responses, or watch the rewards. It was clear from the study that reinforcement style had little to do with the effectiveness of the lesson. Students watched the reinforcements for a substantial time to begin with, but ultimately opted to continue the program with little attention to the rewards. Students spent significantly more time watching the frames that demonstrated the question and correct response when they answered incorrectly than they spent listening or watching an animation intended for their delight. The implications for software publishers and purchasers are threefold: 1) Effort needs to be given in examination and evaluation of educational software concerning its learning design. 2) Programs designed as instructional tutorials should be structured economically, without the extensive reinforcement frills. 3) Continued research should be aimed at identifying the most efficient reinforcement strategies in operant-style computer assisted instruction