A study of interdiurnal pressure and temperature variations in the free atmosphere over North America

The three-dimensional distribution of pressure and its variation with time are intimately associated with the principal weather phenomena. However, this association is indirect rather than direct and the link connecting the two is the horizontal and vertical field of motion. The relationship between the field of motion and the variation in time and space of pressure is one of interdependence. On the other hand, the field of motion seems causally related to most weather phenomena. Neither of these relationships is fully understood so it is not surprising that current attempts to utilize pressure distributions as tools for predicting weather phenomena do not meet with complete success. In this connection, the variation of pressure with time is of prime interest, inasmuch as it reflects physical processes currently in operation in the atmosphere and as it presages future developments. Study of these processes through an analysis of pressure variations is complicated by the compressibility of the atmosphere and by the observed fact that mass variations of either sign may be taking place within any layer in the atmosphere quite independently of variations of the mass within any other layer. Since the instantaneous distribution of pressure and its variation with time are hydrostatically related to the temperature field and its changes, it is advantageous to study the two elements simultaneously. Any consideration of the temperature field in the atmosphere inevitably requires that some attention must be devoted to the tropopause as a major first order discontinuity of temperature. Moreover, the significance of this general reglon of the atmosphere as a location of processes important in determining tropospheric pressure variations has been stressed by the Austrian School of Meteorologists. The problem of achieving a better understanding of the nature of pressure changes may be attacked in one or more of three different, though complementary ways - theoretically, descriptively, and/or, statistically. The theory has been discussed by Stüve, Defant, V. Bjerknes, J. Bjerknes, Solberg, and Bergeron, and more recently by Wulf and Obloy, J. Bjerknes and Holmboe, and Petterssen, as well as by others. The descriptive approach by means of detailed analyses of selected situations has been demonstrated in many investigations all over the world, among which are several particularly interesting studies in North America and Europe. The statistical treatment was first attempted by Dines and Schedler and considerably extended and refined by Haurwitz and others and by Penner. The statistical studies mentioned above have been based upon an analysis of mean conditions and mean changes in vertical columns of air assumed to be in hydrostatic equiiibrium. Since the problem is essentially dynamic, such analyses can never present the complete picture of the physical processes involved in pressure changes. However, in view of the present unsatisfactory state of knowledge concerning these processes, such statistical studies play an extremely valuable role in improving the general understanding of the complex systems of mass variations which are integrated into pressure changes by the atmosphere. They present mean conditions against which descriptive and theoretical studies may be evaluated with regard to representativeness and applicability, respectively. Furthermore, they are systematic summaries of actual conditions which may properly serve as a guide to the direction in which further theoretical and descrptive investigations may most profitably proceed. The paucity of upper air data has restricted the scope of previous studies along these lines and so it is the aim of this investigation to utilize the information recently available as a result of the well organized network of radiosonde observation stations in North America to extend these studies. In particular, it is desired to investigate the geographical and seasonal differences in the mean values of pressure and temperature variation at all levels and the related upper air conditions. It is hoped that the greater number of observations in the stratosphere may throw some light on its true importance with respect to tropospheric pressure variations and that mean conditions throughout the lower atmosphere may be so defined that it will be possible to set up certain requirements which any proposed mechanism for pressure changes must satisfy in order to be thoroughly consistent with reality. The observational material and the methods of analysis will be discussed in Chapter I. Chapters II, III, and IV will be devoted to a description of the results of the statistical analysis. Since the interpretations of one aspect of the study depend upon the results of some of the other aspects, most of the interpretations and conclusions wil be discussed in Chapter V

Attitudes of Teachers Toward Supervisory Services Employed by Building Principals

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A study of some factors of role deprivation on selected aspects of the behavior, attitudes, and values of nurses in the outpatient department

Thesis (M.S.)--Boston Universit

Catalase-Containing Silica Particles as Ultrasound-Based Hydrogen Peroxide Sensors to Determine Infected From Noninfected Fluid Collections in Humans.

OBJECTIVE. Hydrogen peroxide (H2O2) plays a key role in neutrophil oxidative defense against infection. Catalase-containing silica nanoshells are nanoparticles that generate O2 microbubbles imaged with ultrasound in the presence of elevated H2O2. We aimed to determine whether ultrasound-detectable O2 microbubbles produced by catalase-containing silica nanoshells can determine whether fluid collections drained from patients are infected. SUBJECTS AND METHODS. During this HIPAA-compliant, institutional review board-approved study, 52 human fluid samples were collected from clinically required image-guided percutaneous drainage procedures. Catalase-containing silica nanoshells were added to the fluid samples during imaging in real time using a Sequoia-512 15L8-S linear transducer (Siemens Healthcare). Production of detectable microbubbles was graded subjectively as negative (noninfected) or positive (infected) with low, moderate, or high confidence by a single observer blinded to all clinical data. The truth standard was microbiology laboratory culture results. Performance characteristics including ROC curves were calculated. RESULTS. Microbubble detection to distinguish infected from noninfected fluids was 84% sensitive and 72% specific and offered negative and positive predictive values of 89% and 64%, respectively. The AUC was 0.79. Six of nine false-positive samples were peritoneal fluid collections that were all collected from patients with decompensated cirrhosis. CONCLUSION. The presence of elevated H2O2 indicated by microbubble formation in the presence of catalase-containing silica nanoshells is sensitive in distinguishing infected from noninfected fluids and offers a relatively high negative predictive value. False-positive cases may result from noninfectious oxidative stress. Catalase-containing silica nanoshells may constitute a novel point-of-care test performed at time of percutaneous drainage, potentially obviating placement of drains into otherwise sterile collections and minimizing risk of secondary infection or other complication

Human operator performance of remotely controlled tasks: Teleoperator research conducted at NASA's George C. Marshal Space Flight Center

The capabilities within the teleoperator laboratories to perform remote and teleoperated investigations for a wide variety of applications are described. Three major teleoperator issues are addressed: the human operator, the remote control and effecting subsystems, and the human/machine system performance results for specific teleoperated tasks

A vertical profile of deep horizontal current near Cape Lookout, North Carolina

The acoustic transit times for a float to sink to a bottom-anchored triangular array of disposable transponders are used to construct a horizontal current profile in the anticyclonic shear region of the Gulf Stream, southeast of Cape Lookout, North Carolina...

Trophic classification of Tennessee Valley area reservoirs derived from LANDSAT multispectral scanner data

LANDSAT MSS data from four different dates were extracted from computer tapes using a semiautomated digital data handling and analysis system. Reservoirs were extracted from the surrounding land matrix by using a Band 7 density level slice of 3; and descriptive statistics to include mean, variance, and ratio between bands for each of the four bands were calculated. Significant correlations ( 0.80) were identified between the MSS statistics and many trophic indicators from ground truth water quality data collected at 35 reservoirs in the greater Tennessee Valley region. Regression models were developed which gave significant estimates of each reservoir's trophic state as defined by its trophic state index and explained in all four LANDSAT frames at least 85 percent of the variability in the data. To illustrate the spatial variations within reservoirs as well as the relative variations between reservoirs, a table look up elliptical classification was used in conjunction with each reservoir's trophic state index to classify each reservoir on a pixel by pixel basis and produce color coded thematic representations

Numerical Investigation of the Layer-Inversion Phenomenon in Binary Solid Liquid Fluidized Beds

Layer inversion behaviour in binary-solid liquid fluidized beds is examined using a Combined Continuum and Discrete Model. A suitable bidisperse system was selected from information in the literature. By simulating the fluidization of the system at a range of liquid velocities, varying degrees of segregation and mixing have been observed