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

Some Models for Estimating Technical and Scale Inefficiencies in Data Envelopment Analysis

Abstract: In management contexts, mathematical programming is usually used to evaluate a collection of possible alternative courses of action en route to selecting one which is best. In this capacity, mathematical programming serves as a planning aid to management. Data Envelopment Analysis reverses this role and employs mathematical programming to obtain ex post facto evaluations of the relative efficiency of management accomplishments, however they may have been planned or executed. Mathematical programming is thereby extended for use as a tool for control and evaluation of past accomplishments as well as a tool to aid in planning future activities. The CCR ratio form introduced by Charnes, Cooper and Rhodes, as part of their Data Envelopment Analysis approach, comprehends both technical and scale inefficiencies via the optimal value of the ratio form, as obtained directly from the data without requiring a priori specification of weights and/or explicit delineation of assumed functional forms of relations between inputs and outputs. A separation into technical and scale efficiencies is accomplished by the methods developed in this paper without altering the latter conditions for use of DEA directly on observational data. Technical inefficiencies are identified with failures to achieve best possible output levels and/or usage of excessive amounts of inputs. Methods for identifying and correcting the magnitudes of these inefficiencies, as supplied in prior work, are illustrated. In the present paper, a new separate variable is introduced which makes it possible to determine whether operations were conducted in regions of increasing, constant or decreasing returns to scale in multiple input and multiple output situations. The results are discussed and related not only to classical single output economics but also to more modern versions of economics which are identified with "contestable market theories."

The effect of sampling error on convergence, improper solutions, and goodness-of-fit indices for maximum likelihood confirmatory factor analysis

Abstract: A Monte Carlo study assessed the effect of sampling error and model characteristics on the occurrence of nonconvergent solutions, improper solutions and the distribution of goodness-of-fit indices in maximum likelihood confirmatory factor analysis. Nonconvergent and improper solutions occurred more frequently for smaller sample sizes and for models with fewer indicators of each factor. Effects of practical significance due to sample size, the number of indicators per factor and the number of factors were found for GFI, AGFI, and RMR, whereas no practical effects were found for the probability values associated with the chi-square likelihood ratio test.

Noise-induced transitions

Abstract: In this paper I will deal with the effect of external random perturbations, “noise”, on chemical systems and other open nonlinear systems. As a concrete example let us consider a CSTR. This is an open system and as such subject to external constraints, namely the concentrations of the chemical species in the feed streams, the flow rate, the stirring rate, the temperature, and the incident light intensity in the case of a photochemical reaction. These external constraints characterize the state of the environment of the open system and will, in general, fluctuate more or less strongly. Such environmental fluctuations are particularly important for natural systems; here random fluctuations are always present and their amplitude is not necessarily small as in laboratory systems. In the latter systems the experimenter will of course try to minimize the effect of random perturbations, though it is impossible to eliminate noise completely. Clearly, random external noise is ubiquitous in open systems, but this fact by itself would hardly warrant a systematic study of the effects of external fluctuations. The question is whether noise is more than a mere nuisance we have to live with. Is there any hope of finding interesting physics? The intuitive, and wrong, answer would be negative: The system averages out rapid fluctuations and the only trace of external noise would be a certain fuzziness in the state of the system. Of course, if the state of the system becomes unstable, the fluctuations initiate the departure from the unstable state. Then the dynamics of the system take over and the system evolves to a new stable state.

A developmental study of data envelopment analysis in measuring the efficiency of maintenance units in the U.S. air forces

Abstract: : There are four basic questions related to efficiency and capability which are of particular interest to officials in the military services who are interested in better ways of evaluating military capability and efficiency: (1) What level of military capability can the services achieve with available resources? (2) What capability is required, and where are the shortfalls? (3) What resource acquisitions or redistributions are needed to achieve maximum improvement in efficiency and effectiveness? and (4) How can management systems be changed to improve the identification and correction of factors which limit the readiness and efficiency of our military operations? The last question, which differs in its emphasis from the other three, provides an opening to the topics that will be addressed in this report. In particular, reported are results from a study of DEA (Data Envelopment Analysis) as a method for evaluating the efficiency of Air Force Wings--or, more precisely, their maintenance operations--as elements in Numbered Units in the U.S. Air Force.

Congestive heart failure with normal systolic function

Abstract: Although there have been isolated reports of congestive heart failure (CHF) with normal systolic function, the prevalence and characteristics of this condition have not previously been described. Accordingly, 188 patients with CHF undergoing radionuclide ventriculography were prospectively evaluated. Sixty-seven (36%) had a normal ejection fraction (EF) of 0.45 or greater, and 121, an abnormal EF of less than 0.45. Of these, 72 (55 with an abnormal EF [group I] and 17 with a normal EF [group II]) were also reviewed for clinical characteristics. There was no demographic difference between groups, except that systemic hypertension appeared to be a contributing factor in 65% of the patients in group II, compared with 23% of the patients in group I (p

Reminders to physicians from an introspective computer medical record. A two-year randomized trial.

Abstract: We developed a computer-stored medical record system containing a limited set of the total clinical data base--primarily diagnostic studies and treatments. This system responds to its own content according to physician-authored reminder rules. To determine the effect of the reminder messages generated by 1490 rules on physician behavior, we randomly assigned practitioners in a general medicine clinic to study or control groups. The computer found indications for six different actions per patient in 12 467 patients during a 2-year study: 61 study group residents who received computer reminders responded to 49% of these indications; 54 control group residents, to only 29% (p less than 0.0001). Preventive care (occult blood testing, mammographic screening, weight reduction diets, influenza and pneumococcal vaccines) was affected. The intentions of the study group to use a given action for an indication predicted their response to the indications (p less than 0.03, r2 = 0.33). The intentions of the control residents did not.

Histologic grading of adenoid cystic carcinoma of the salivary glands

Abstract: Seventy-nine patients with adenoid cystic carcinoma arising in salivary glands were studied to determine whether a correlation existed between the morphologic features of the tumor and the prognosis. Three histologic grades were established: Grade I, tumors with tubular and cribriform areas but without solid components; Grade II, cribriform tumors that were either pure or mixed with less than 30% of solid areas; and Grade III, tumors with a predominantly solid pattern. Cumulative survival rates at 15 years were 39%, 26%, and 5%, for Grades I, II, and III, respectively. Grade III tumors were larger, recurred frequently, and killed the patients within 4 years. Grade I lesions were smaller, were amenable to complete surgical excision, and had a protracted clinical course. Grade II tumors lay between the other two forms both clinically and pathologically. Other important prognostic features of the adenoid cystic carcinoma were its primary site, its presence or absence at surgical margins, and the anatomic structures it involved.

Biological communities at the Florida escarpment resemble hydrothermal vent taxa.

Abstract: Dense biological communities of large epifaunal taxa similar to those found along ridge crest vents at the East Pacific Rise were discovered in the abyssal Gulf of Mexico. These assemblages occur on a passive continental margin at the base of the Florida Escarpment, the interface between the relatively impermeable hemipelagic clays of the distal Mississippi Fan and the jointed Cretaceous limestone of the Florida Platform. The fauna apparently is nourished by sulfide rich hypersaline waters seeping out at near ambient temperatures onto the sea floor.

Issues in the design of group decision support systems

Abstract: This paper deals with a number of issues pertinent to the design of group decision support systems. It notes that the need for such systems, whether designed by users or vendors, is a consequence of the clash of two important forces: (1) the environmentally-imposed demand for more information sharing in organizations, and (2) the resistance to allocating more managerial and professional time to attending meetings. The paper focuses on three major issues in the design of these systems: 1) system capabilities, 2) system delivery modes, and 3) system design strategies, and discusses the relationship of these issues to system use and survival. The relevance of numeric information, textual information, and relational information in a decision-group context are examined, and various system capabilities for displaying and using such information are noted.

Preface to topics in data envelopment analysis

Abstract: This paper serves as an introduction to a series of three papers which are directed to different aspects of DEA (Data Envelopment Analysis) as follows: (1) uses and extensions of window analyses' to study DEA efficiency measures with an illustrative applications to maintenance activities for U.S. Air Force fighter wings, (2) a comparison of DEA and regression approaches to identifying and estimating, sources of inefficiency by means of artificially generated data, and (3) an extension of ordinary (linear programming) sensitivity analyses to deal with special features that require attention in DEA. Background is supplied in this introductory paper with accompanying proofs and explanations to facilitate understanding of what DEA provides in the way of underpinning for the papers that follow. An attempt is made to bring readers abreast of recent progress in DEA research and uses. A synoptic history is presented along with brief references to related work, and problems requiring attention are also indicated and possible research approaches also suggested.

Excitation of internal kink modes by trapped energetic beam ions

Abstract: Energetic trapped particles are shown to have a destabilizing effect on the internal kink mode in tokamaks. The plasma pressure threshold for the mode is lowered by the particles. The growth rate is near the ideal magnetohydrodynamic value, but the frequency is comparable to the trapped particle precission frequency. A model for the instability cycle gives stability properties, associated particle losses, and neutron emissivity consistent with the fishbone events observed in PDX.

The Sociology of Conversion

Abstract: This essay reviews recent research on religious conversion, particularly within the context of "new" religious movements. It addresses three fundamental issues pertinent to the study of conversion: first, the conceptualization and nature of conversion; second, the analytic status of converts' accounts; and third, the causes of conversion. The chapter concludes with a proposed agenda for subsequent research on conversion and related topics.

Changes in the Levels of Plant Secondary Metabolites Under Water and Nutrient Stress

Abstract: Increasing interest in the stress physiology of higher plants has, in the last few years, greatly expanded our knowledge concerning the effects of stresses such as drought, freezing, nutrient deficiencies, disease and insect attack on plant metabolism. This work, however, has concentrated on the influences of stress on the basic processes of growth and development (primary metabolism). Very little attention has been paid to the changes in secondary metabolism that may be occurring. Information on the effects of stress conditions on secondary metabolites has come mainly from research efforts to maximize the yield of active constituents from herb, spice and drug plants and from attempts to reduce the levels of toxins in certain food and forage crops. Advances in our understanding of the functional roles of secondary metabolites in plants, however, and new information about how pest resistance is altered by stress should stimulate additional interest in the responses of secondary metabolites to stress.

The drinking philosophers problem

Abstract: The problem of resolving conflicts between processes in distributed systems is of practical importance. A conflict between a set of processes must be resolved in favor of some (usually one) process and against the others: a favored process must have some property that distinguishes it from others. To guarantee fairness, the distinguishing property must be such that the process selected for favorable treatment is not always the same. A distributed implementation of an acyclic precedence graph, in which the depth of a process (the longest chain of predecessors) is a distinguishing property, is presented. A simple conflict resolution rule coupled with the acyclic graph ensures fair resolution of all conflicts. To make the problem concrete, two paradigms are presented: the well-known distributed dining philosophers problem and a generalization of it, the distributed drinking philosophers problem.

View Definition and Generalization for Database Integration in a Multidatabase System

Abstract: Access to a heterogeneous distributed collection of databases can be simplified by providing users with a logically integrated interface or global view. There are two aspects to database integration. Firstly, the local schemas may model objects and relationships differently and, secondly, the databases may contain mutually inconsistent data. This paper identifies several kinds of structural and data inconsistencies that might exist. It describes a versatile view definition facility for the functional data model and illustrates the use of this facility for resolving inconsistencies. In particular, the concept of generalization is extended to this model, and its importance to database integration is emphasized. The query modification algorithm for the relational model is extended to the semantically richer functional data model with generalization.

The Demand for Labor in the Long Run

Abstract: The theory of the demand for labor is presented along with a catalog and critique of methods that are used to estimate the parameters that describe empirical labor-demand and substitution possibilities. A critical survey is presented of studies of own-price demand elasticities for labor as a whole and for workers categorized by demographic group, of substitution parameters among workers of different types, and of workers for capital. The main findings are: 1) The long-run constant-output demand elasticity for labor that istreated as homogeneous is between .15 and .5; 2) Own-price demand elasticities are higher for workers that have less general human capital embodied and them; 3) Skilled labor and physical capital are p-complements; and 4) More tentatively, youths and wornenare q-substitutes in production. The implications and importance for policy of these and other results are discussed. Suggestions for improving the literature and narrowing the range of knowledge of the underlying parameters, especially by concentrating more on disaggregated and even microeconornic data, are presented.

Concerns of College Students Regarding Business Ethics

Abstract: Although some attention has been devoted to assessing the attitudes and concerns of businesspeople toward ethics, relatively little attention has focused on the attitudes and concerns of tomorrow's business leaders, today's college students. In this investigation a national sample was utilized to study college students' attitudes toward business ethics, with the results being analyzed by academic classification, academic major, and sex. Results of the investigation indicate that college students are currently somewhat concerned about business ethics in general, and that female students in particular are more concerned about ethical issues than are their male counterparts.

Polymorphous low-grade adenocarcinoma of minor salivary glands. A study of 14 cases of a distinctive neoplasm.

Abstract: M. D. Anderson Hospital cases diagnosed as adenocarcinoma of minor salivary glands before 1977 were reviewed. Within this heterogeneous group of neoplasms there was identified one clinicopathologic tumor entity, which we have designated "polymorphous low-grade adenocarcinoma." The 14 tumors in that category were characterized by cytologic uniformity and histologic diversity; growth patterns varied (both within and among cases) from solid to tubular to papillary to cribriform (pseudoadenoid cystic) to fascicular, while the cells were always small to medium-sized, regular, and lacking in nuclear atypia. Mitotic figures were infrequent, and tumor necrosis was seen in only one instance (a recurrent neoplasm). Clear cytoplasm, oxyphilic and mucinous metaplasia, and intratubular calcification were sometimes present, and stromal mucinization and hyalinization were common. The tumors were always unencapsulated, and exhibited extension into surrounding tissues including bone. The 14 patients ranged in age from 27 to 76 years (median, 64 years). Eight were male and six were female; eight were white and six were black. The neoplasm was intraoral in all cases, involving the palate in 11, the buccal mucosa in two, and the posterior mandibular area in one. Local recurrence developed in one case, cervical lymph node metastasis in one, and both recurrence and cervical lymph node metastasis in two. The number of successive recurrences ranged up to three, and the interval to recurrence varied up to nine years (the interval to metastasis up to five years). Although radical surgical procedures were necessary for tumor control in some cases, no distant metastases occurred and all patients were clinically tumor-free at latest follow-up.

Masculinity, femininity, and gender-related traits: a conceptual analysis and critique of current research.

Abstract: Publisher Summary The research employing the Bern Sex Role Inventory (BSRI), Personal Attributes Questionnaire (PAQ), and other instruments containing separate M and F scales has fundamentally been inspired by a shift in societal attitudes, shared by most social scientists, toward a more egalitarian view of the status of women and the relationships between the sexes. Substitution of traditional bipolar theories with the proposition that masculinity and femininity are independent dimensions and that androgyny, a combination of both, is associated with greater psychological competency than sex-typing held out the promise that a society, in which roles are not differentially assigned to men and women, except as dictated by biology, is both feasible and desirable. The chapter discusses that the multidimensional nature of sex-role and other gender-related phenomena is also beginning to be recognized. Although gender identity is essentially dimorphic, the general statement that masculine and feminine attributes and behaviors cannot or do not coexist has been effectively refuted. Androgyny, defined as the possession of substantial numbers of desirable attributes and response dispositions currently stereotyped as masculine and feminine, or as an indifference to sex-role standards that leads the person to behave according to his or her individual predilections may turn out to have the benefits assigned to it.

Water Solubilities of Polynuclear Aromatic and Heteroaromatic Compounds

Abstract: The water solubilities of several polynuclear aromatic and heteroaromatic hydrocarbons have been compiled and reviewed for consistency through correlations with parameters such as surface area, molecular volume, and boiling point. The carbocycles and oxygen and sulfur heterocycles were governed by the same correlative equations, thereby indicating that these heteroatoms entered into only a limited degree of hydrogen bonding. Equations representing the nitrogen heterocycles differed from their carbocyclic counterparts by an approximately constant amount, suggesting that while the solubilizing effect of the nitrogen heteroatom may be large, it tends to remain constant within a similar series of compounds.

Victimization Rates, Exposure to Risk, and Fear of Crime

Abstract: Studies of fear of crime repeatedly point to an apparent paradox: fear of crime and risk of victimization are related inversely among demographic groups (i.e., age, race, and sex groups). However, data from surveys of Chicago residents show that fear of crime is related positively to victimization rates once they are adjusted for exposure to risk. When demographic variables are included with the adjusted rates as predictors of fear of crime, age and sex effects persist. Even so the present findings indicate that fear of crime should not be interpreted as an irrational or unjustified response and that fear can be reduced by lowering victimization rates.

A silicon phthalocyanine and a silicon naphthalocyanine: synthesis, electrochemistry, and electrogenerated chemiluminescence

Abstract: : The synthesis, spectral characterization, and electrochemical behavior of bis(tri-n-hexylsiloxy)-2,3-phthalocyaninatosilicon (SiPc(OR)2), its dimer (RO(SiPcO)2R), and its naphthalocyanine analog (SiNc(OR)2) are described. All compounds show near UV absorption corresponding to Soret and N bands and intense absorption in the visible-near IR region corresponding to Q-bands. In CH2Cl2, within the solvent stability limit, there are two reductions and one oxidation for SiPc(OR)2 and two reductions and two oxidations for RO(SiPcO)2R and SiNc(OR)2; all appear as reversible one electron waves, although n=2 for the dimer. The difference in the peak potentials of the first oxidation and first reduction waves agrees well with the excitation energy and fluorescence (corresponding to Q-bands) of SiPc(OR)2 and SiNc(OR)2.