Showing papers by "University of Texas at Arlington published in 1984"

Sulphur-rich volcanic eruptions and stratospheric aerosols

Abstract: Data from direct measurements of stratospheric optical depth, Greenland ice-core acidity, and volcanological studies are compared, and it is shown that relatively small but sulfur-rich volcanic eruptions can have atmospheric effects equal to or even greater than much larger sulfur-poor eruptions. These small eruptions are probably the most frequent cause of increased stratospheric aerosols. The possible sources of the excess sulfur released in these eruptions are discussed.

Applicability of the fluorescein diacetate method of detecting active bacteria in freshwater.

Abstract: Fluorescein diacetate (FDA) hydrolysis was evaluated as a means to detect actively metabolizing bacteria in freshwater. Fluorescein diacetate, a nonfluorescent derivative of fluorescein, can be transported across cell membranes and deacetylated by nonspecific esterases. Resultant fluorescein accumulates within cells and allows direct visualization by epifluorescent microscopy. Application of FDA to a variety of freshwater habitats yielded estimates of active cells ranging from 6–24% of the total population. These estimates were 49–61% lower than estimates of active cells obtained from measures of electron transport activity. The difference was attributed to low permeability of the fluorogen through the outer membrane of heterotrophic gram-negative cells. Data suggest that FDA hydrolysis as a means of detecting active bacteria may be limited to environments rich in eucaryotes and gram-positive cells.

Improved Pel-Recursive Motion Compensation

Abstract: A pel-recursive motion estimation technique for television coding was introduced by Netravali and Robbins [1]. This method basically involves computing a motion displacement and then separating the pels into predictable and unpredictable segments. The addresses required to identify these segments and thus enable the motion estimation algorithm are transmitted along with pel error data. The original algorithms are slow to converge, i.e., many iterations are required to obtain an accurate displacement estimate. This research introduces extensions to the basic algorithm of [1] and offers two significant improvements. First, convergence speed is improved substantially, which means that the algorithms can better tolerate motion changes and diverse motion within the picture. Secondly, explicit address information is not required, as it is contained implicitly in the motion compensation algorithm. For the sequences examined, this method proved superior to that of explicitly transmitting the address data. This algorithm has much better convergence rates and has prediction rates better than the original.

Selected Effects of Salesperson Sex and Attractiveness in Direct Mail Advertisements

Abstract: This study assesses whether sex and attractiveness of a sales representative used in a direct mail advertisement or the sex of the receiver of that advertisement influences the receiver's decision ...

Employee Ownership Work Attitudes, and Power Relationships

Abstract: Relationships of employee equity in the company with work attitudes, information, and desired influence were examined in a prosperous firm converted to employee ownership by its management. Questio...

Heat Transfer Enhancement in a Paraffin Wax Thermal Storage System

Abstract: Heat transfer enhancement in a thermal storage system consisting of vertically arranged fins between a heated and cooled horizontal finned-tube arrangement is reported. The high thermal expansion coefficient and low viscosity of paraffin wax, at temperatures above 50/sup 0/C, are utilized to induce natural convection in the liquid phase even at small thicknesses. The experimental data on the rate of production of liquid as a function of time and temperature of the hot surface is presented. The photographs of the melted zone indicate a naturally buoyant flow induced in the neighborhood of the vertical fins causes a rapid melting of the solid wax and a downdraft along the cooler solid phase surface. The heat transfer coefficient at the interface is calculated from experimentally determined instantaneous locations of the moving boundary.

A job severity index for the evaluation and control of lifting injury

Abstract: Two large field studies were conducted to test the validity of the Job Severity Index (JSI) as an engineering tool for the control of manual materials-handling injury. Comparisons were made between the calculated JSIs of 453 individuals working in 101 different jobs and the injuries sustained by the same individuals over a period of 1057881 exposure hours (529 exposure years). The results revealed the existence of a job severity threshold above which the incidence, severity, and cost of injury dramatically increased. It was concluded that the JSI method can effectively be used to control injuries caused by the manual lifting of loads.

Acid-base properties of α-ribazole and the thermodynamics of dimethylbenzimidazole association in alkylcobalamins

Abstract: Preparation de l'α-ribazole et caracterisation par analyse elementaire RMN de H 1 et C 13 , spectre UV-visible, valeurs du pKa. Preparation de 7 alkylcobalamines et determination de leurs pKa a la meme temperature que pour l'α-ribazole. On determine les constantes de stabilite apparentes et on calcule pour cette substitution de coordinat les changements d'enthalpie et d'entropie

Short-lived manganate(VI) and manganate(V) intermediates in the permanganate oxidation of sulfite ion

Abstract: La reaction globale entre pH 8 et 12 est: 2MnO 4 − +3SO 3 2− +H 2 O→2MnO 2 +3SO 4 2− +2OH − ; elle consiste en 2 etapes: accumulation et disparition de M 4 O 4 2−

Fast decimation-in-time algorithms for a family of discrete sine and cosine transforms

Abstract: Fast decimation-in-time (DIT) algorithms for the various discrete cosine transforms (DCT) and discrete sine transforms (DST) are systematically developed, based on a radix-2 factorization of the transformation matrix. The results indicate these to be attractive alternatives to existing algorithms in terms of computational complexity and structural simplicity.

Empirical identification of the criteria for effective affirmative action programs.

Abstract: Legislation prohibits discrimination in most social activities. Organizations have implemented affirmative action programs to comply with the law and to attempt to reduce discrimination. Research indicates, however, that discrimination still exists. Research must therefore identify the key factors that make affirmative action programs truly effective. The authors designed this study to capture the policies of personnel and affirmative action officers in institutions of higher learning regarding criteria for effective affirmative action programs. The research identified 13 potential criteria. The results suggest that attitudinal and procedural factors — e.g., commitment from higher administration, receptive attitudes of key personnel, formal and informal grievance procedures — were the most important criteria for program effectiveness. The institution type — i.e., public versus private — and size — number of students — have no moderating effects.

Remarks on First and Second Order Periodic Boundary Value Problems

Abstract: On etudie les problemes aux valeurs limites periodiques d'ordre 1 et 2 suivants: u'=f(t,u), u(0)=u(2π) et −u''=f(t,u), u(0)=u(2π); u'(0)=u'(2π). On obtient l'existence de solutions extremales comme limites d'iterees monotones

Electrodeposition of CdTe Thin Films

Abstract: Cadmium telluride thin films were fabricated on Ti and Nesatron substrates by electrodeposition and characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analyses (EDAX), optical transmission measurements, and photoelectrochemical (PEC) studies. The deposition-bath preparation procedure was slightly modified from the literature method to permit initial speciation of TeO/sub 2/ and thereby increase the loading level of Te in the film. New data are presented on the electrochemistry of the deposition process and on the cyclic voltammetric behavior of TeO/sub 2/ containing electrolytes in the pH range from about 0.7 to 11.0. The films after suitable annealing in an Ar atmosphere show x-ray diffraction behavior consistent with a hexagonal structure. Data from EDAX show that the Cd/Te ratio in the film is sensitive to the annealing process. Concomitantly, the conductivity also changes from p-type to n-type, as shown by PEC measurements on the films containing a protective ..cap alpha..-PbO/sub 2/ coating in contact with alkaline polysulfide electrolytes. Finally, some preliminary data are presented on PEC cells based on these CdTe thin films in a nonaqueous electrolyte system comprising the ferrocene/ferricenium ion redox couple.

Coproduction, Equity, and the Distribution of Safety

Abstract: In response to decreases in federal funding affecting a number of urban services and substantial reductions in other fiscal resources, municipal governments have developed several new methods to de

The GRE: A Question of Validity in Predicting Performance in Professional Schools of Social Work

Abstract: Several forceful arguments have been presented which raise questions about the use of the GRE as a primary factor in the admissions process. Two issues that are raised repeatedly are concerned with...

A stratified sampling approach to compensating for non-random sedimentation of phytoplankton cells in inverted microscope settling chambers

Abstract: A pronounced “edge effect” resulting in non-random cell sedimentation is documented for standard-design inverted microscope counting chambers. Comparison of mean cell densities of two green algae from random fields in central and peripheral regions of chambers substantiate a marked peripheral settling bias. The non-random settling pattern is independent of phytoplankton cell size and population density over the ranges encountered in this analysis. If this problem is not compensated for, the magnitude of the bias is such that large errors in estimates of mean cell density/chamber can result. A stratified sampling approach is developed to minimize the error resulting from non-random settling without increasing the amount of time spent enumerating cells. Counting of random fields rather than patterned transects is strongly recommended as the standard procedure in phytoplankton studies.

Action as a Text: Gadamer's Hermeneutics and the Social Scientific Analysis of Action

Abstract: This paper argues that Gadamer's hermeneutics offers a methodological perspective for social and political theory that overcomes the impasse created by the dichotomy between the positivist and humanist approaches to social action. Both the positivists’attempt to replace the actors’subjective concepts with the objective concepts of the social scientist and the humanists’attempt to describe meaningful action strictly in the social actors’terms have been called into question in contemporary discussions. Gadamer's approach, which is based on the hermeneutical method of textual interpretation, offers an alternative to both the positivist and humanist perspectives. Gadamer argues that understanding a text involves the fusing of the conceptual schemes of author and interpreter. Relying on Ricoeur's analysis of the parallels between actions and texts, it is argued that this understanding of the process of textual interpretation can be profitably applied to the analysis of social action. This application, furthermore, provides a means of analyzing social action that transcends the dichotomy between the positivist and humanist approaches. Gadamer's approach legitimizes the imposition of the observer's conceptual scheme without denying the constitutive role of the social actors’concepts.

Deep Sea Drilling Project, Leg 77, southeastern Gulf of Mexico

Abstract: In January 1981, R/V Glomar Challenger drilled five holes in the southeastern Gulf of Mexico to provide ground data for extensive seismic surveys and to document the pre-Tertiary history of the Gulf. Holes 535 and 540 were drilled in a basinal terrane for maximum penetration of the Cretaceous-Tertiary sequence. Rhythmic alternations of light bioturbated and dark laminated carbonaceous limestone represent the Early Cretaceous interval. Some of the dark layers are rich but immature oil source rocks. The limestones resemble the Blake-Bahama Formation in the North Atlantic but their stratigraphic age overlaps in part with the Hatteras Shale. Late Cretaceous rocks are almost totally missing in the basin sites and the Cenozoic section consists of chalk and marly carbonate ooze. Holes 536,537, and 538A were drilled on high-standing fault blocks. Hole 537 recovered phyllite that records 40 Ar/ 39 Ar plateau ages of about 500 m.y. and is overlain by an Early Cretaceous deepening sequence of alluvial to littoral elastics and oolitic-oncolitic limestones, capped by a thin sequence of Cretaceous and Cenozoic pelagics. In Hole 538A, basement consists of mylonitic gneiss and amphibolite, intruded by several generations of diabase dikes (that is, “transitional” crust). 40 Ar/ 39 Ar dates of hornblendes and biotite from the regional metamorphic rocks suggest a 500-m.y. (“Pan-African”) age with mild late Paleozoic thermal overprint. 40 Ar/ 39 Ar whole-rock dates from the dikes suggest intrusions between 190 and 160 m.y. ago. Basement is covered by a thin layer of pelagic chalk, followed by Early Cretaceous skeletal-oolitic limestones and, finally, Cretaceous-Tertiary pelagics. The oolitic-oncolitic limestones at both sites represent either parts of a shallow-water carbonate platform or platform talus deposited in deep water. Hole 536 bottomed in shallow-water dolomite (Jurassic or Permian), overlain by middle Cretaceous skeletal limestones with shallow-water biota and intercalations of pelagic chalk, interpreted as Cretaceous talus at the foot of the Campeche Bank. Cretaceous-Tertiary chalk and carbonate ooze cap the sequence. Among the most significant results of the leg are: (1) recovery of “transitional” crust with early Paleozoic (Pan-African) metamorphic rocks, (2) recovery of Early Cretaceous deep-water limestones with immature petroleum source beds, (3) recovery of mid-Cretaceous platform talus resembling the reservoirs in the Poza Rica and probably some of the Reforma fields of Mexico, and (4) discovery of a Late Cretaceous hiatus of 30 m.y. that corresponds approximately to the “mid-Cretaceous unconformity” recognized widely on seismic records in the Gulf of Mexico.

Testing the invulnerability of laboratory island communities to invasion.

Abstract: One hundred communities were developed through the controlled introductions of microorganisms to beakers over a six month period of time. Following three months of development, a series of three separate previously unencountered species were introduced into each community. The persistences of these invaders were monitored and their relationships to invaded community complexity, composition and history of development evaluated. The null hypothesis that colonization success is independent of community complexity cannot be rejected. The rate at which species were introduced during development of these communities, as well as beaker size, influenced the invasion success of Dictyosphaerium, but not Staurastrum or Platydorina. The assembled communities were of two types: those dominated by Ochromonas and those domnated by Paramecium bursaria. Ochromonas dominated communities were invulnerable to the invasion of the above 3 species; no clear pattern of invulnerability was evident for P. bursaria communities.

Visual and haptic perception of three-dimensional solid forms

Abstract: Subjects sorted 24 solid forms into groups on the basis of perceived similarity of shape, and rated each on a series of physical attributes under either visual or haptic conditions. Multidimensional scaling analyses within each condition produced highly similar two-dimensional solutions. Both first dimensions were related to size judgments, and both second dimensions were related to shape judgments. Correlations between haptic and visual attribute ratings were high, and the between-attribute correlational structures within each condition were also very similar. The findings are discussed in terms of Gibson’s notion of partial perceptual invariances.