Showing papers by "University of Alabama published in 1991"

Regression with Graphics: A Second Course in Applied Statistics

Abstract: 1. Variable Distributions 2. Bivariate Regression Analysis 3. Basics of Multiple Regression 4. Regression Criticism 5. Fitting Curves 6. Robust Regressions 7. Logit Regression 8. Principle Components and Factor Analysis

The Role of Soy Products in Reducing Risk of Cancer

Abstract: Since the initial recognition that diet plays a role in the etiology of certain cancers, particularly cancers of the breast and colon, considerable progress has been made in identifying dietary patterns associated with cancer risk. There is general agreement that a high-fat, low-fiber diet, like that consumed by much of the industrialized world, increases cancer risk and that plant-based diets, rich in whole grains, legumes, and fruits and vegetables, are protective. It has been, however, considerably more difficult to identify specific foods, types of food, or components of foods that influence cancer risk. The recent workshop on The Role of Soy Products in Cancer Prevention, sponsored by the National Cancer Institute, had two objectives: I) to evaluate the role of soybeans, food products derived from soybeans, and specific components of soybeans in the dietary prevention of cancer and 2) to recommend research initiatives and approaches for further studies of the effect of soy intake on human cancer risk. The meeting was chaired by Stephen Barnes and organized by Mark Messina.

The next generation of moderator research in personality psychology.

Abstract: The concept of a moderator variable has a long and checkered history in personality psychology. In this article I review the methodological and conceptual advances in recent moderator variable research. I then report the results of a number of empirical analyses of three newly proposed idiographic moderator variables: scalability, metatraits, and construct similarity, as well as the ipsatized variance index. The results of these analyses indicate that moderator effect sizes in personality can be expected to correspond to a correlation of about .10. I then consider two recent prescriptions, (a) aggregating trait-specific moderators into general ones, and (b) evaluating joint (e.g., triple interaction) moderator effects. Following these prescriptions did not increase the size of the moderator effects in these data. I conclude that moderator effects in personality will be small, and will thus be most reliably detected in very large samples with predictors that are strongly related to the criteria. Even small moderator effects can be important and interesting in the context of theory disconfirmation. However, moderator variables generally will not serve to transform weak relations among personality variables into strong ones.

The three-dimensional structure of canine parvovirus and its functional implications

Abstract: The three-dimensional atomic structure of a single-stranded DNA virus has been determined. Infectious virions of canine parvovirus contain 60 protein subunits that are predominantly VP-2. The central structural motif of VP-2 has the same topology (an eight-stranded antiparallel beta barrel) as has been found in many other icosahedral viruses but represents only about one-third of the capsid protein. There is a 22 angstrom (A) long protrusion on the threefold axes, a 15 A deep canyon circulating about each of the five cylindrical structures at the fivefold axes, and a 15 A deep depression at the twofold axes. By analogy with rhinoviruses, the canyon may be the site of receptor attachment. Residues related to the antigenic properties of the virus are found on the threefold protrusions. Some of the amino termini of VP-2 run to the exterior in full but not empty virions, which is consistent with the observation that some VP-2 polypeptides in full particles can be cleaved by trypsin. Eleven nucleotides are seen in each of 60 symmetry-related pockets on the interior surface of the capsid and together account for 13 percent of the genome.

Adjuvant chemotherapy for resectable squamous cell carcinomas of the head and neck: Report of intergroup study 0034

Abstract: To test the efficacy of sequential chemotherapy as an adjuvant to surgery and postoperative radiotherapy for patients with locally-advanced but operable squamous cell cancers of the head and neck region, a randomized clinical trial was conducted under the auspices of the Head and Neck Intergroup (Radiation Therapy Oncology Group, Southwest Oncology Group, Eastern Oncology Group, Cancer and Leukemia Group B, Northern California Oncology Group, and Southeast Group). Eligible patients had completely resected tumors of the oral cavity, oropharynx, hypopharynx, or larynx. They were then randomized to receive either three cycles of cis-platinum and 5-FU chemotherapy followed by postoperative radiotherapy (CT/RT) or postoperative radiotherapy alone (RT). Patients were categorized as having either "low-risk" or "high-risk" treatment volumes depending on whether the surgical margin was greater than or equal to 5 mm, there was extracapsular nodal extension, and/or there was carcinoma-in-situ at the surgical margins. Radiation doses of 50-54 Gy were given to "low-risk" volumes and 60 Gy were given to "high-risk" volumes. A total of 442 analyzable patients were entered into this study with the mean-time-at-risk being 45.7 months at the time of the present analysis. The 4-year actuarial survival rate was 44% on the RT arm and 48% on the CT/RT arm (p = n.s.). Disease-free survival at 4 years was 38% on the RT arm compared to 46% on the CT/RT arm (p = n.s.). At 4 years the local/regional failure rate was 29% vs. 26% for the RT and CT/RT arms, respectively (p = n.s.). The incidence of first failure in the neck nodes was 10% on the RT arm compared to 5% on the CT/RT arm (p = 0.03 without adjusting for multiple testing) and the overall incidence of distant metastases was 23% on the RT arm compared to 15% on the CT/RT arm (p = 0.03). Treatment related toxicity is discussed in detail, but, in general, the chemotherapy was satisfactorily tolerated and did not affect the ability to deliver the subsequent radiotherapy. Implications for future clinical trials are discussed.

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I, an 8 month campaign of monitoring NGC 5548 with IUE

Abstract: This is an electronic version of an article published in The Astrophysical Journal. Clavel, J. et al. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I. An 8 month campaign of monitoring NGC 5548 with IUE. The Astrophysical Journal 366 (1991): 64-81

Optimal design of a welded beam via genetic algorithms

Abstract: Introduction T HE welded beam structure is a practical design problem that is often used as a bench-mark problem in testing different optimization techniques This problem is one of a family of structural optimization problems, which consists of a nonlinear objective function and five nonlinear constraints There exist a number of optimization techniques that are successfully used in solving such problems Some of these methods, like geometric programming, require an extensive problem formulation prior to the optimization procedure Other methods, such as gradient search techniques, require derivative information that may not exist for others This paper considers the application of a genetic algorithm (GA) in obtaining optimal design parameters for a welded beam structure GAs are systematic search procedures—both global and efficient—based on the mechanics of natural genetics GAs search through large spaces quickly even though they only require payoff information Furthermore, because of the processing leverage associated with GAs, the method has a much more global perspective than many common methods in engineering optimization techniques GAs have been applied to a variety of optimization problems—engineering, social sciences, physical sciences, computer sciences, biology, and others In the welded beam problem described here, GAs are compared with other optimization techniques and found to have surprising speed of convergence to near-optimal solutions Simulation results suggest that GAs can be used to solve other problems of this class with similar efficiency

Mean reversion in stock prices? a reappraisal of the empirical evidence

Abstract: The paper re-examines the empirical evidence for mean-reverting behaviour in stock prices. Comparison of data before and after World War II shows that mean reversion is entirely a pre-war phenomenon. Using randomization methods to calculate significance levels, we find that the full sample evidence for mean reversion is weaker than previously indicated by Monte Carlo methods under a Normal assumption. Further, the switch to mean-averting behaviour after the war is about to be too strong to be compatible with sampling variation. We interpret these findings as evidence of a fundamental change in the stock returns process and conjecture that it may be due to the resolution of the uncertainties of the 1930's and 1940's.

Reproduction of Antarctic benthic marine invertebrates: Tempos, modes, and timing

Abstract: Work on the life histories of common antarctic benthic marine invertebrates over the past several decades demands a revision of several widely held paradigms. First, contrary to expectations derived from work on temperate species, there is little or no evidence for temperature adaptation with respect to reproduction (gametogenesis), development, and growth. It remains to be determined whether the slow rates of these processes reflect some inherent inability to adapt to low temperatures, or are a response to features of the antarctic marine environment not directly related to low temperature, such as low food resources. Secondly, contrary to the widely accepted opinion designated as “Thorson's rule,” pelagic development is common in many groups of shallow-water marine invertebrates. In fact in some groups, such as asteroids,pelagic development is as prevalent in McMurdo Sound, the southern-most open-water marine environment in the world, as in central California. In other taxonomic groups, especially gastropods, there does seem to be a genuine trend toward non-pelagic development from tropical to antarctic latitudes. Although this trend has been predicted by theoretical models, its underlying causes appear to be group specific rather than general. Thirdly, pelagic lecithotrophic development, often considered to be of negligible importance, occurs in many shallow-water antarctic marine macroinvertebrates. Pelagic lecithotrophy may be an adaptation to a combination of poor food conditions in antarctic waters most of the year and slow rates of development. Nevertheless, some of the most abundant and widespread antarctic marine invertebrates have pelagic planktotrophic larvae that take very long times to complete development to metamorphosis. These species areparticularly prevalent in productive regions of shallow water (<30 m), which are frequently disturbed by anchor ice formation, and the production of numerous pelagic planktotrophic larvaemay represent a strategy for colonization. Although planktotrophic larvae tend to be seasonal in occurrence, their production is not linked particularly closely to the mid-summer pulse of phytoplankton production. These larvae show no evidence of starvation, even during times when phytoplankton abundance is very low, and they may depend on unusual sources of food, such as bacteria. How they escape the selective conditions that apparently led to a predominance of non-feeding modes of development in antarctic marine invertebrates remains as a major challenge for antarctic marine biology.

The relationship between sense of community and subjective well-being: A first look

Abstract: The relationship between sense of community and subjective well-being (SWB) was tested by conducting telephone interviews with three random samples in South Carolina and Alabama (ns = 151, 399, and 442). Respondents answered the 17-item Sense of Community Scale (Davidson & Cotter, 1986), a measure of three facets of SWB (happiness, worrying, and personal coping), and questions about their demographic characteristics and subjective evaluations of their community. Partial correlation coefficients were computed between sense of community and SWB, partialling out the influence of demographic and community-evaluation variables. Sense of community was significantly related to SWB in all three samples. The effects were especially pronounced for the happiness facet of SWB. Implications are drawn for theory and intervention, and recommendations are made for further research.

X-ray diffraction evidence for aromatic π hydrogen bonding to water

Abstract: THEinteraction of water with aromatic moieties is of importance in biological systems, as most encounter an aqueous environment during their normal functions. For example, common constituents of globular proteins such as phenylalanine, tryptophan and tyrosine possess aromatic side-chains1 that may encounter water molecules inside the protein structure2. As a model for hydrogen-bonding interactions with aromatics, we have performed X-ray diffraction studies on crystalline Na4[calix[4]arene sulphonate].13.5H2O. Calixarene molecules3,4contain hydrophobic cavities comprised of aromatic groups, rimmed, in the case of the water-soluble sulphonates (R = -SO3Na), by hydrophilic groups5,6. In the absence of a hydrophobic guest, the cavity invariably contains a water molecule. The low-temperature X-ray crystal structure of this compound (see Table 1 and Fig. 1) shows direct evidence for hydrogen bonding between water and the aromatic π electrons in the solid state.

Mithramycin inhibits SP1 binding and selectively inhibits transcriptional activity of the dihydrofolate reductase gene in vitro and in vivo.

Abstract: The promoter of the human dihydrofolate reductase (DHFR) gene contains two consensus binding sites for the DNA binding protein Sp1. DNAse protection and gel mobility shift assays demonstrate binding of recombinant Sp1 to both decanucleotide Sp1 binding sequences which are located 49 and 14 base pairs upstream of the transcription start site. The more distal of the two binding sites exhibits a somewhat higher affinity for Sp1. The G-C specific DNA binding drug, mithramycin, binds to both consensus sequences and prevents subsequent Sp1 binding. Promoter-dependent in vitro transcription of a DHFR template is selectively inhibited by mithramycin when compared to the human H2b histone gene. A similar effect is also noted in vivo. Mithramycin treatment of MCF-7 human breast carcinoma cells containing an amplified DHFR gene induces selective inhibition of DHFR transcription initiation, resulting in a decline in DHFR mRNA level and enzyme activity. This selective inhibition of DHFR expression suggests that it is possible to modulate the overexpression of the DHFR gene in methotrexate resistant cells.

The Appalachian-Ouachita rifted margin of southeastern North America

Abstract: Promontories and embayments along the late Precambrian-early Paleozoic Appalachian-Ouachita continental margin of south-eastern North America are framed by a northeast-striking rift system offset by northwest-striking transform faults. Inboard from the continental margin, basement fault systems have two sets of orientation; one is northeast parallel with rift segments, and the other is northwest parallel with transform faults. Late Precambrian clastic and volcanic syn-rift rocks overlie Precambrian basement rocks along the Appalachian Blue Ridge. Lower Cambrian sandstone at the base of a transgressive passive-margin succession over-steps the rift-fill successions and basement rocks, defining the time of transition from an active rift to a passive margin along the Blue Ridge. Locally thick Early Late Cambrian and older sedimentary rocks fill downthrown blocks of the intracratonic Mississippi Valley-Rough Creek-Rome graben system and Birmingham basement fault system. These basement fault systems, which indicate north-west-southeast extension like the Blue Ridge rift, are overstepped by Upper Cambrian strata. The northwest-striking Southern Oklahoma fault system is interpreted to be a transform fault that propagated into the continent from the Ouachita rift. Early and Middle Cambrian rift-related igneous rocks along the fault system and adjacent Precambrian basement are overstepped by Upper Cambrian sandstone. The differences in age of rift-related rocks suggest a spreading-center shift at the beginning of the Cambrian Period from the Blue Ridge rift to the Ouachita rift southwest of the Alabama-Oklahoma transform fault. From Early to Early Late Cambrian, a small component of extension propagates north-eastward to form the intracratonic fault systems northeast of the transform fault, but most of the extension of the Ouachita rift was transformed along the Alabama-Oklahoma transform fault to the Mid-Iapetus Ridge outboard from the Blue Ridge passive margin.

Spectral dependence of glandular tissue dose in screen-film mammography.

Abstract: The average glandular tissue dose in mammography is generally determined from published tables with knowledge of the breast entrance skin exposure, x-ray tube target material, beam quality (half-value layer [HVL]), breast thickness, and breast composition. Using a carefully designed and experimentally validated Monte Carlo simulation, the authors found that average glandular dose also depends on x-ray tube voltage and, to a lesser extent, on x-ray tube voltage waveform. For currently employed molybdenum target-molybdenum filter source assemblies, a difference in dose of 10% or more is possible in estimating the average glandular dose obtained with different x-ray tube voltages but with the same HVL. Presented are normalized average glandular tissue doses in units of radiation absorbed dose per unit entrance skin exposure for different tube voltages and tube voltage waveforms as well as for different breast thicknesses and compositions and beam filtrations.

The Influence of Domestic and International Politics on the President's Use of Force:

Abstract: Ostrom and Job (1986) found that domestic, political factors are more influential on the president's decision to use military force than characteristics of the international environment. These results pose a serious challenge to realists' assumptions regarding the motives of states and the separability of domestic and foreign policy. This article reexamines Ostrom and Job's arguments and introduces a new indicator, a measure of the severity of ongoing international crises, to provide a better assessment of the relative effect of the international environment on presidential decision making. This severity index is significantly associated with the use of force by the United States from 1949 through 1976, and proves to be more influential than the international indicators used by Ostrom and Job. Nevertheless, domestic political factors remain most consequential in the president's decision to use force short of war.

Long-term results of a controlled prospective study with transfusion of donor-specific bone marrow in 57 cadaveric renal allograft recipients.

Abstract: Experimental studies have shown that antilymphocyte globulin combined with transfusion of donor-specific bone marrow cells can induce partial tolerance to allograft tissue. We have adapted these protocols to clinical use and present the results of 57 cadaveric renal allograft recipients who received Minnesota ALG followed by the transfusion of cryopreserved donor-specific bone marrow. A group of 54 patients received the contralateral kidney and similar immunosuppression without the marrow transfusion and serve as controls. Both groups received quadruple immunosuppression with MALG, cyclosporin, azathioprine, and prednisone. In the bone marrow group, after a 10-14 day induction course of ALG, cryopreserved marrow was transfused on the seventh day after the last dose of ALG. The median follow-up in both groups is 16 months, (range 2.5-33 months). Six grafts have been lost in the bone marrow group, (three rejections, 2 deaths [Cr 2.0, 2.3], 1 recurrent disease). In the control group 16 grafts have been lost (13 rejections, 3 deaths [Cr 1.7, 2.5, 3.0]). Five patients in the control group have biopsy-proved chronic rejection compared to one in the bone marrow group. 17 patients in the bone marrow group have been tapered off the prednisone, and three of these patients have had mild late rejection episodes without graft loss. The two groups were compared for differences in the number of rejection episodes, estimated renal plasma flow, glomerular filtration rate, and urine protein. No differences were found. The allograft survival of the bone marrow group was significantly greater (P less than .01) than the control group. The graft survival rates for the bone marrow group at 12 and 18 months were 90% (confidence limits [CL] 85-94) and 85% (CL 78-90), respectively. In the the control group the 12 and 18 month allograft survival rates were 71% (CL 63-78) and 67% (CL 58-74), respectively. The survival in the control group was similar to our overall transplant experience with quadruple therapy. Mixed lymphocyte culture analysis shows a trend to diminished donor-specific responsiveness in the bone marrow group. The use of cryopreserved donor-specific bone marrow is associated with improved allograft survival in cadaveric kidney allograft recipients. However, a more effective induction protocol is needed to reduce the overall number of rejection episodes.

Scapular fractures. Analysis of 113 cases.

Abstract: Scapular fractures have been the subject of study since Desault's treatise of 1805, but few large-scale studies have been completed with long-term follow-up evaluation of displaced scapular neck and spine fractures. This series of 148 fractures in 116 scapulae (113 patients) appears to be the largest ever reported and the only one with a follow-up study of a significant group (24 patients). Significant disability was found in patients with displaced scapular spine and neck fractures: (1) pain at rest in 50%-100%, (2) weakness with exertion in 40%-60%, and (3) pain with exertion in 20%-66%. Based on these findings, the indications for operative management should be expanded to include displaced scapular neck and spine fractures. Using extensile exposure through a posterior Judet incision, rigid internal fixation, and early motion, results in eight cases were excellent. All patients recovered at least 85 degrees of glenohumeral abduction, normal scapulothoracic motion, and none had resting pain, night pain, or pain with abduction. The minimum follow-up study period was 15 months.

A Controlled Trial of Acyclovir for Chickenpox in Normal Children

Abstract: Background. Chickenpox, the primary infection caused by the Varicella Zoster virus, affects more than 3 million children a year in the United States. Although usually self-limited, chickenpox can cause prolonged discomfort and is associated with infrequent but serious complications. Methods. To evaluate the effectiveness of acyclovir for the treatment of chickenpox, we conducted a multi-center, double-blind, placebo-controlled study involving 815 healthy children 2 to 12 years old who contracted chickenpox. Treatment with acyclovir was begun within the first 24 hours of rash and was administered orally in a dose of 20 mg per kilogram of body weight four times daily for five days. Results. The children treated with acyclovir had fewer varicella lesions than those given placebo (mean number, 294 vs. 347; P<0.001), and a smaller proportion of them had more than 500 lesions (21 percent, as compared with 38 percent with placebo; P<0.001). In over 95 percent of the recipients of acyclovir no new lesion...

Biocompatibility of the Bioelastic Materials, Poly(GVGVP) and Its γ-Irradiation Cross-Linked Matrix: Summary of Generic Biological Test Results

Abstract: The complete series of the recommended generic biological tests for materials and devices in contact with tissues and tissue fluids and blood have been carried out by an independent testing laborat...

Class i mhc-restricted cytotoxic t lymphocyte recognition of cells infected with human cytomegalovirus does not require endogenous viral gene expression^

Abstract: The human pathogen CMV, is a major cause of morbidity and mortality in immunocompromised hosts. The CD8+ class I-restricted CTL response to CMV assists in preventing progression of CMV infection to life-threatening disease; however, the viral Ag recognized by CD8+ CTL are not well characterized. In general, virus-specific CTL recognize endogenously synthesized viral proteins processed and presented associated with class I MHC molecules. Although proteins or inactivated virions have been experimentally delivered to the cytoplasm to result in class I MHC presentation, this mode of Ag delivery to the class I processing pathway after natural viral entry has not been documented in humans. Our data demonstrate that the CMV-specific class I-restricted CTL response in individuals latently infected with CMV is predominantly specific for selected structural virion proteins introduced into the cell after viral penetration and efficient recognition occurs in the absence of de novo viral gene expression. This CTL response may provide a biological advantage for limiting the spread of infection after CMV reactivation because infected cells are lysed before viral assembly.

Analysis of radiative scattering for multiple sphere configurations

Abstract: An analysis of radiative scattering for an arbitrary configuration of neighbouring spheres is presented. The analysis builds upon the previously developed superposition solution, in which the scattered field is expressed as a superposition of vector spherical harmonic expansions written about each sphere in the ensemble. The addition theorems for vector spherical harmonics, which transform harmonics from one coordinate system into another, are rederived, and simple recurrence relations for the addition coefficients are developed. The relations allow for a very efficient implementation of the 'order of scattering' solution technique for determining the scattered field coefficients for each sphere. Prediction of the radiative absorption and scattering characteristics of small particles is important to researchers in a number of fields, e.g. atmospheric modelling, analysis of radiative transfer from flames, and development of nonintrusive laser-based optical diagnostic methods. Computation of the radiative characteristics of spherical particles from Lorenz-Mie theory is practically a trivial matter due to the existence of efficient computer codes (Bohren & Huffman 1983). However, it is not unusual to encounter situations in which the individual particles, while spherical in shape, are so close together that the 'isolated sphere' assumption inherent in Lorenz-Mie theory is questionable. A common example is soot formed in combustion processes. Electron micrographs of the individual soot particles reveal them to be agglomerates of a large number of primary, spherical particles (Dobbins

Service Quality: the Front‐stage vs. the Back‐stage Perspective

Abstract: Evaluates customers′ and employees′ service quality expectations and perceptions from the example of a hospital environment. Considers employees′ responses in administrative and nonadministrative categories. Notes differences between the groups and discusses the managerial implications arising from the differences found. Includes a detailed description of the methodology involved in the study.

Genetic diversity of the attachment protein of subgroup B respiratory syncytial viruses.

Abstract: Respiratory syncytial (RS) virus causes repeated infections throughout life. Between the two main antigenic subgroups of RS virus, there is antigenic variation in the attachment protein G. The antigenic differences between the subgroups appear to play a role in allowing repeated infections to occur. Antigenic differences also occur within subgroups; however, neither the extent of these differences nor their contributions to repeat infections are known. We report a molecular analysis of the extent of diversity within the subgroup B RS virus attachment protein genes of viruses isolated from children over a 30-year period. Amino acid sequence differences as high as 12% were observed in the ectodomains of the G proteins among the isolates, whereas the cytoplasmic and transmembrane domains were highly conserved. The changes in the G-protein ectodomain were localized to two areas on either side of a highly conserved region surrounding four cysteine residues. Strikingly, single-amino-acid coding changes generated by substitution mutations were not the only means by which change occurred. Changes also occurred by (i) substitutions that changed the available termination codons, resulting in proteins of various lengths, and (ii) a mutation introduced by a single nucleotide deletion and subsequent nucleotide insertion, which caused a shift in the open reading frame of the protein in comparison to the other G genes analyzed. Fifty-one percent of the G-gene nucleotide changes observed among the isolates resulted in amino acid coding changes in the G protein, indicating a selective pressure for change. Maximum-parsimony analysis demonstrated that distinct evolutionary lineages existed. These data show that sequence diversity exists among the G proteins within the subgroup B RS viruses, and this diversity may be important in the immunobiology of the RS viruses.

Language learning tasks: teacher intention and learner interpretation

Abstract: Recent explorations in task-based pedagogy have pointed out that learning outcome is the result of a fairly unpredictable interaction between the   

Comparison of two methods of assessing physical activity in the coronary artery risk development in young adults (CARDIA) study

Abstract: Physical activity was assessed by questionnaire among 4,956 young blacks and whites aged 18-30 years at the baseline examination (1985-1986) of the Coronary Artery Risk Development in Young Adults (CARDIA) study, a longitudinal study of cardiovascular risk factors. The Physical Activity Recall questionnaire categorized all activity during the previous week, while the Physical Activity History questionnaire quantified participation in 13 specific activities during the previous year. This report compares the two questionnaires with regard to their characterization of the activity levels of the sociodemographic subgroups of the study population and their associations with known physiologic correlates of physical activity. Both questionnaires resulted in the same physical activity patterns for sex (men greater than women) and age (younger greater than older) strata. However, the mean Physical Activity History score was higher in white women than in black women, while the Physical Activity Recall scores were nearly equal. The Physical Activity History score was directly related to educational status, and the Physical Activity Recall score was inversely related to educational status. The Physical Activity History score was generally more strongly associated with physiologic variables known to be related to physical activity (e.g., treadmill test duration). Based upon these findings, which may only be appropriate in this age group, it was concluded that the Physical Activity History score was the more valid measure of habitual physical activity in this study group of young adults.

Metallocene/polypropylene structural relationships: Implications on polymerization and stereochemical control mechanisms

Abstract: A series of group 4 metallocenes possessing chiral ligand environments have been characterized and their structures are compared with their propylene polymerizations. Isotactic, syndiotactic, hemiisotactic, and atactic polypropylenes are produced selectively with chiral monoalkyl metallocene cations paired with perfluorotetraphenyl borate; analogous to the results obtained using methylaluminoxane as a cocatalyst. The relative catalyst stereospecificities suggest specific π-face selectivities and nonbonded contacts. Trends with solvents, temperatures, and catalyst structures are consistent with contact ion pairing for iPr[CpFlu]Zr-P(+) in liquid propylene. The specificities of differently structured metallocenes imply chain-migratory monomer addition reactions.

The influence of ownership on performance: An empirical study

Abstract: This research examines the relationship between ownership structure and financial performance in the context of the agency theory. It improves upon previous research by presenting an improved risk-adjusted performance measure, by using a larger sample size than prior work and also by controlling for firm size differences. The results suggest that ownership is significantly related to firm financial performance even after controlling for size.

An ( S -1, S ) inventory system with emergency orders

Abstract: In this paper, we develop an approximate model of an inventory control system in which there exist two options for resupply, with one having a shorter lead-time. We assume that demand and the fixed ordering costs are small relative to the holding cost so that a one-for-one ordering policy is appropriate. We consider a policy for placing emergency orders that uses information about the age of outstanding orders. We derive the steady-state behavior of this policy and present some computational results.

Acquired immune dysfunction in cats with experimentally induced feline immunodeficiency virus infection: comparison of short-term and long-term infections.

Abstract: Specific pathogen-free domestic cats with experimentally induced feline immunodeficiency virus (FIV) infections of short duration (less than or equal to 10 months) exhibited depressed total leukocyte and neutrophil numbers and a marginally decreased lymphocyte proliferative response to pokeweed mitogen (PWM), while cats with infections of more lengthy duration (greater than or equal to 25 months) exhibited normal leukocyte and neutrophil numbers but a dramatic loss of responsiveness to both PWM and concanavalin A (Con A). Cats with short-term infections exhibited a decrease in the percentage of CD4+ lymphocytes in peripheral blood and a corresponding depression of the CD4+:CD8+ ratio. Cats with long-term infections exhibited a similar but more profound perturbation of the CD4+ lymphocyte subset that also included a decrease in the absolute number of CD4+ cells. The decreased responsiveness to Con A and PWM in cats infected long term paralleled the decline in CD4+ cell counts, and the duration of infection was directly correlated with the decrease in the percentage of CD4+ cells. These data provide evidence supporting the hypothesis that FIV is the cause of an immune dysfunction in cats, with distinct similarities to that produced by human immunodeficiency virus (HIV) in people.