Showing papers by "Indiana University published in 1987"

Leaving College: Rethinking the Causes and Cures of Student Attrition

Abstract: As enrollments continue to decline, student retention is increasingly vital to the survival of most colleges and universities. In the second edition of this text, Tinto synthesizes far-ranging research on student attrition and on actions institutions can and should take to reduce it. The key to effective retention, Tinto demonstrates, is in a strong commitment to quality education and the building of a strong sense of inclusive educational and social community on campus. This revised and expanded edition incorporates the explosion of recent research and policy reports on why students leave higher education. Incorporating current data, Tinto applies his theory of student departure to the experiences of minority, adult and graduage students, and to the situation facing commuting institutions and two-year colleges. He has revised his theory, giving new emphasis to the central importance of the classroom experience and to the role of multiple college communities.

The genetic defect causing familial Alzheimer's disease maps on chromosome 21

Abstract: Alzheimer's disease is a leading cause of morbidity and mortality among the elderly. Several families have been described in which Alzheimer's disease is caused by an autosomal dominant gene defect. The chromosomal location of this defective gene has been discovered by using genetic linkage to DNA markers on chromosome 21. The localization on chromosome 21 provides an explanation for the occurrence of Alzheimer's disease-like pathology in Down syndrome. Isolation and characterization of the gene at this locus may yield new insights into the nature of the defect causing familial Alzheimer's disease and possibly, into the etiology of all forms of Alzheimer's disease.

Manufacturing strategy, environmental uncertainty and performance: a path analytic model

Abstract: In recent years, researchers and practitioners are paying increasing attention to the phenomenon of manufacturing strategy. However, there exists no formal theory of manufacturing strategy to explain the phenomenon. There is a real need for empirical studies for the development of such a theory. This study takes a step in that direction by clarifying, organizing and integrating terms and concepts relevant to manufacturing strategy in the process of conducting an empirical investigation of key manufacturing strategy variables. The empirical section of this study based on data gathered from 35 manufacturers found that environmental uncertainty influenced manufacturing strategy variables such as Manufacturing Flexibility, and the Role of Manufacturing Managers in Strategic Decision Making. The manufacturing strategy variables, in turn, influenced business performance.

Thermal Tolerance of Avian Embryos: A Review

Abstract: Avian eggs usually experience temperatures of 30 to 400C during the incubation period, but eggs often cool to much lower temperatures. Hyperthermia is less common. Passerines do not show higher incubation temperatures than other orders that have been studied extensively. Field measurements of incubation temperatures are usually lower than the optimal temperatures for development found in laboratory studies. Some species regulate egg temperatures closely throughout incubation; but in at least one penguin species, mean egg temperature increases and ranges of egg temperature decrease through the incubation period. Both the optimal temperature for continuous exposure and the range of temperatures producing high survivorship differ among species. Species also differ in their responses to temperature exposures of limited duration. Thus, the use of a "physiological zero" applicable to all species is not warranted. Penguins have both a lower optimum and a broader range of acceptable incubation temperatures than do other species studied. Age, duration, and temperature of exposure significantly affect survivorship. Hyperthermia is evidently more injurious to the developing embryo than is hypothermia. Resistance to cold exposure is a heritable trait, but the genetics and physiology of the response(s) are not known. For older embryos, the physiological effects of hyperthermia are similar to those of adult birds in terms of the organ systems that are first to fail. An estimate of thermal tolerance for short exposures in most species studied is 16 to 41 C and, for exposures lasting several hours, 36 to 390C.

Effects of recombinant human granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndromes.

Abstract: The myelodysplastic syndromes are characterized by ineffective hematopoiesis and refractory cytopenias. In an attempt to improve hematopoiesis, we administered recombinant human granulocyte–macrophage colony-stimulating factor (GM-CSF) to eight patients with myelodysplastic syndrome, as part of a Phase I trial. The GM-CSF was given by continuous intravenous infusion daily for two weeks and then again after a two-week rest period. Over the entire dose range tested (30 to 500 μg per square meter of body-surface area), treatment was associated with marked increases in peripheral-blood leukocytes (5- to 70-fold), including granulocytes (5- to 373-fold), in all eight patients. The absolute number of monocytes, eosinophils, and lymphocytes increased in all patients. Three of eight patients also had 2- to 10-fold increases in platelet counts and improvement in erythropoiesis, with the result that two of three patients who had required red-cell and platelet transfusions no longer needed them (at 20 to 27...

Concordance for type 2 (non-insulin-dependent) diabetes mellitus in male twins.

Abstract: Concordance for Type 2 (non-insulin-dependent) diabetes was determined in 250 monozygotic and 264 dizygotic white male twin pairs who participated in the National Heart, Lung, and Blood Institute Twin Study. These twins were born between 1917 and 1927 and were identified from military records without regard to disease status. We examined surviving members of the cohort twice--at mean ages of 47 and 57 years--and obtained 1-h post-load glucose tests and medication histories. Diagnostic criteria for Type 2 diabetes included a glucose value greater than or equal to 13.9 mmol/l or current use of antidiabetic medication; possible Type 1 (insulin-dependent) diabetic twins were excluded. A strong genetic predisposition to Type 2 diabetes was suggested by 3 lines of evidence from the second examination: (1) 58% of monozygotic co-twins of diabetic twins were themselves diabetic compared with an expected prevalence of 10%; (2) only 1 of 15 originally disease-discordant, monozygotic twin pairs remained discordant for diabetes; and (3) 65% of non-diabetic monozygotic co-twins of diabetic twins had elevated glucose values. Because concordance for diabetes was less than 100% for twins aged 52-65 years and because twins varied in age at onset of disease, non-genetic factors may also influence diabetes development. Among the 19 monozygotic twins pairs discordant for diabetes, diabetic twins did not differ from their non-diabetic co-twins in obesity, diet, alcohol consumption, or education. However, compared with unrelated non-diabetic twins of the same ages, non-diabetic co-twins of diabetic twins gained more weight as adults (p less than 0.02) and had higher glucose levels (p less than 0.03).

Attention and learning processes in the identification and categorization of integral stimuli.

Abstract: The relationship between subjects' identification and categorization learning of integral-dimension stimuli was studied within the framework of an exemplar-based generalization model. The model was used to predict subjects' learning in six different categorization conditions on the basis of data obtained in a single identification learning condition. A crucial assumption in the model is that because of selective attention to component dimensions, similarity relations may change in systematic ways across different experimental contexts. The theoretical analysis provided evidence that, at least under unspeeded conditions, selective attention may play a critical role in determining the identification-categorization relationship for integral stimuli. Evidence was also provided that similarity among exemplars decreased as a function of identification learning. Various alternative classification models, including prototype, multiple-prototype, average distance, and "value-on-dimensions" models, were unable to account for the results. This article seeks to characterize performance relations between the two fundamental classification paradigms of identification and categorization. Whereas in an identification paradigm people identify stimuli as unique items (a one-to-one stimulus-response mapping), in a categorization paradigm people classify items into groups (a many-to-one stimulus-response mapping). The present study of the identification-categorization relationship is motivated by the recent "exemplar view" of categorization proposed by investigators such as Brooks (1978), Hintzman and Ludlam (1980), and Medin and Schaffer (1978). According to the exemplar view, people represent categories by storing individual category exemplars in memory. Classification decisions are based on the similarity of stimuli to the stored exemplars. This view contrasts with some other approaches that assume that people form category "summary" representations such as a prototype or a rule. A suggestion that follows from the exemplar view is that there may be highly regular and systematic relations between identification and categorization performance. Presumably, when subjects learn to identify stimuli, a unique representation of each stimulus is stored in memory. Furthermore, the extent to which individual stimuli are confused during identification is

The estimation of a conceptual model of nontraditional undergraduate student attrition

Abstract: The purpose of this study was to estimate a conceptual model of nontraditional student attrition. Data were gathered from 624 nontraditional (commuter, part-time) freshmen at a midwestern urban university enrolling 22,000 students. For these nontraditional students, dropout was a function of GPA and credit hours enrolled, as well as the utility of education for future employment, satisfaction with the student role, opportunity to transfer, and age affecting dropout through intent to leave. In addition, absence from class, age, high school performance, and ethnicity had indirect effects on dropout through GPA. These results suggested that nontraditional students dropped out of college for academic reasons or because they were not committed to attending the institution, but their reasons for leaving were unrelated to social factors at school. The findings helped validate the conceptual model.

Genetic linkage of bilateral acoustic neurofibromatosis to a DNA marker on chromosome 22

Abstract: Bilateral acoustic neurofibromatosis (BANF) is a severe autosomal dominant disorder involving development of multiple tumours of the nervous system including meningiomas, gliomas, neurofibromas and particularly bilateral acoustic neuromas. We have used genetic linkage analysis with DNA markers to establish that the defective gene causing BANF is on chromosome 22, and is therefore distinct from the gene for the von Recklinghausen form of neurofibromatosis, which maps to chromosome 17. Linked DNA markers will be particularly valuable in BANF, facilitating early detection of tumours and thereby permitting more effective surgical intervention. In view of the reported loss of genes on chromosome 22 in meningiomas and acoustic neuromas, the genetic localization of the primary BANF defect strongly supports the concept that the disease locus encodes a 'tumour suppressor' gene. Isolation of this gene should provide insights into the pathogenesis of acoustic neuromas and other nervous system tumours, as well as into the control of proliferation and differentiation of neural crest cells.

From text to speech: the MITalk system

Abstract: This book describes the most comprehensive system yet developed for the automatic conversion of English text to intelligible and natural sounding synthetic speech. It offers detailed accounts of the various components any speech technologist needs to consider - algorithms for morphological analysis, letter-to-sound rules, syntactic analysis, lexical stress, timing and pitch, together with segmental synthesis. The MIT text-to-speech system, on which Jonathan Allen has collaborated with Sheri Hunnicutt, Dennis Klatt and other colleagues, has set new standards for intelligibility, linguistic sophistication and methods of evaluation. This study will be an invaluable resource not only for professionals in the field, but for any reader with an informed interest in natural language processing.

Homozygotes for Huntington's disease

Abstract: Careful comparison of symptomatic individuals with normal controls has revealed the primary biochemical abnormality in many human genetic diseases, particularly recessive disorders1. This strategy has proved less successful for most human disorders which are not recessive, and where a single copy of the aberrant gene has clinically significant effects even though the normal gene product is present. An alternative approach that eliminates the impediment of a normal protein in affected individuals is to study homozygotes for the mutant allele2. For virtually all dominant human disorders in which homozygotes have been described, symptoms have been significantly more severe in the homozygote than in the heterozygote3. Thus, these disorders do not conform to the classical definition of dominance which states that homozygotes and heterozygotes for a defect are phenotypically indistinguishable3–5. Instead, they display incomplete dominance, indicating that the normal allele may play a role in ameliorating the disease process. The D4S10 locus, defined by the probe G8 and linked to the gene for Huntington's disease (HD), has permitted us to identify individuals with a high probability of being homozygous for this autosomal dominant neurodegenerative disorder6–9. These homozygotes do not differ in clinical expression or course from typical HD heterozygotes. HD appears to be the first human disease of genetically documented homozygosity that displays complete phenotypic dominance.

The impact of culture on the cognitive structure of illness

Abstract: This paper presents a theoretical framework for understanding the impact of culture on the processes of symptom recognition, labeling, and help-seeking and consequently on large-scale epidemiological studies involving different ethnic groups. We begin with the assumption that the subjective experience of illness is culture- bound and that the cognitive and linguistic categories of illness characteristic of any culture constrain the interpretative and behavioral options available to individuals in response to symptoms. We hypothesize the existence of learned cognitive structures, through which bodily experiences are filtered, that influence the interpretation of deviations from culturally-defined physical and mental health norms. Certain contradictory findings concerning the self-reported health of Mexican Americans are discussed in order to illustrate the impact of culture on perceived health status.

Bank funding modes: Securitization versus deposits

Abstract: We examine a bank's choice of whether to fund the loans it originates by emitting deposits or to sell the loans to investors. With common knowledge of loan quality and laissez faire banking, we find that the choice is irrelevant. With asymmetric information but without government intervention, we find that better quality assets will be sold (securitized) and poorer quality assets will be funded with deposits. Public regulation can influence the bank's choice; subsidies can cause a bank to favor deposit funding, but mutual funds and third-party insurers may mitigate the effects of governmental subsidies.

Sex steroids and bone mass. A study of changes about the time of menopause.

Abstract: To examine the relationships between bone loss and sex steroids, 84 peri- and postmenopausal women were studied at 4-mo intervals for 3 yr. At each visit, measurements were made of bone mass at the midshaft and distal radius, of steroids, of gonadotropins, and of bone gla protein (BGP). Bone loss was approximately 1% per yr among late perimenopausal and postmenopausal groups, whereas the early perimenopausal group lost no bone. Mean serum estrogen and BGP concentrations predicted rates of bone loss. BGP was negatively correlated with the rate of bone loss (r = -0.45) and with mean estrogen concentrations (r = -0.40). Multivariate regressions showed estrogen concentrations to be strong independent predictors of the slope of bone mass over time. When BGP concentrations were added to the models, the significance of estrogen was reduced, suggesting that a portion of the estrogen effect was mediated through effects on rates of bone remodelling.

Hybrid Molecular Dynamics Algorithms for the Numerical Simulation of Quantum Chromodynamics

Abstract: We discuss two algorithms for the numerical simulation of SU(3) lattice gauge theory with dynamical quarks. Both are based on the hybrid stochastic method of Duane and Kogut. They provide a relatively rapid evolution of the gauge fields through configuration space and good control of errors. One of the algorithms allows the simulation of arbitrary numbers of quarks. Tests of the algorithms are presented as well as initial data from a study of the thermodynamics of quarks and gluons with Kogut-Susskind fermions.

Immediate adjuvant chemotherapy versus observation with treatment at relapse in pathological stage II testicular cancer.

Abstract: Between 1979 and 1984, 195 evaluable patients were entered in an international multicenter study comparing two regimens for patients with completely resected pathological Stage II testicular cancer (that is, with positive retroperitoneal lymph nodes). All patients had undergone orchiectomy and dissection of the retroperitoneal lymph nodes. They were randomly assigned to be treated with two cycles of immediate adjuvant cisplatin-based chemotherapy or to be observed monthly with treatment at relapse. The median follow-up period was four years. Of the 97 patients assigned to adjuvant chemotherapy, 6 (6 percent) had a recurrence; however, only 1 had received adjuvant chemotherapy before the recurrence. Three died (one of testicular cancer), and 94 of the 97 survived. Of the 98 patients who were observed, 48 (49 percent) had a relapse. However, almost all patients with relapses were effectively treated, and 93 of the 98 are alive and disease-free; 3 have died of testicular cancer. No identifiable fact...

Cyclosporine-induced acute renal dysfunction in the rat. Evidence of arteriolar vasoconstriction with preservation of tubular function.

Abstract: Dose-related cyclosporine-induced renal dysfunction is the most frequent adverse effect noted with this exciting immunosuppressive drug. To investigate pathogenetic factors involved, we studied renal tubular function and afferent arteriolar morphology during severe experimental cyclosporine-induced reduction in glomerular filtration rate. Pair-fed male rats were given cyclosporine 50 mg/kg or olive oil vehicle alone by gavage for periods of 3-14 days. Glomerular filtration rate declined progressively, reaching a nadir of 0.18 +/- .05 ml/min/100 g vs. .86 +/- .03 ml/min/100 g in controls at 14 days (P less than 0.001). Despite the severe reduction in glomerular filtration rate there was no difference in fractional sodium excretion, fractional lithium excretion, enzymuria, or in vitro renal cortical slice uptake of tetraethylammonium in cyclosporine and vehicle-treated animals. Light microscopy showed vacuolar changes without evidence of tubular necrosis at 7 and 14 days in cyclosporine-treated rats. Progressive decline in the diameter of the afferent arteriole was noted by scanning electron microscopy. By day 14 the lumenal diameter of afferent arterioles from cyclosporine-treated animals was 8.9 +/- 0.4 micron vs. 13.5 +/- 0.4 micron in controls (P less than 0.05). We conclude that afferent arteriolar vasoconstriction rather than direct tubular injury is a major pathogenetic factor in experimental cyclosporine nephrotoxicity.

Contents of monoamines in forebrain regions of alcohol-preferring (P) and -nonpreferring (NP) lines of rats.

Abstract: The contents of monoamine neurotransmitters and metabolites were assayed in the frontal cortex, nucleus accumbens and anterior striatum of rats from the selectively bred alcohol-preferring P and nonpreferring NP lines Lower levels of serotonin (20–30%) in all three brain regions of P as compared with NP rats lends support to the hypothesis that a decreased metabolic activity and/or innervation by serotonin neurons is associated with the abnormally high volitional intake of ethanol Of additional interest, however, were the approximately 25% lower contents of dopamine and its major metabolites in the nucleus accumbens of the P rats This observation may indicate that P rats have a specific deficiency in the dopaminergic projections from the ventral tegmental area to the nucleus accumbens and, since the accumbens is an important structure in brain reward circuitry, it might also be an important determinant of the excessive volitional intake of alcohol by P rats

The effects of storage of blood and isolated DNA on the integrity of DNA

Abstract: Long-term storage of DNA is required for a number of genetic studies; prior to extraction, blood samples may be subject to elevated temperatures for variable intervals. We have studied the effect of temperatures ranging from -70 degrees C to +65 degrees C on human blood and on DNA extracted from it. DNA in solution stored at ambient temperatures up to 37 degrees C for 6 months was digestible by three different restriction endonucleases, whereas storage at 45 degrees C is deleterious after 6-7 weeks. DNA can be extracted from blood samples stored at -70 degrees C for at least 2 months or at 23 degrees C for a week or more, but blood stored at these temperatures may yield less high-molecular-weight DNA. Cell pellets from which plasma has been removed also can serve as a source of DNA. Isolated DNA stored dry for years (up to 30) is difficult to dissolve and may appear degraded, but a sample stored dry for 13 years and then in solution at -20 degrees C for 7 years appeared to be intact.

The genetic defect in familial Alzheimer's disease is not tightly linked to the amyloid β-protein gene

Abstract: Amyloid β-protein (AP) is a peptide of relative molecular mass (Mr) 42,000 found in the senile plaques, cerebrovascular amyloid deposits, and neurofibrillary tangles of patients with Alzheimer's disease and Down's syndrome (trisomy 21)1–4. Recen t molecular genetic evidence has indicated that AP is encoded as part of a larger protein by a gene on chromosome 21 (refs 5–7). The defect in the inherited autosomal dominant form of Alzheimer's disease, familial Alzheimer's disease (FAD), has been mapped to the same approximate region of chromosome 21 by genetic linkage to anonymous DNA markers8, raising the possibility that this gene product, which could be important in the pathogenesis of Alzheimer's disease, is also the site of the inherited defect in FAD (ref. 5). We have determined the pattern of segregation of the AP gene in FAD pedigrees using restriction fragment length polymorphisms. The detection of several recombination events with FAD suggests that the AP gene is not the site of the inherited defect underlying this disorder.

Transcriptional trans-activating function of hepatitis B virus.

Abstract: The ability of hepatitis B virus (HBV) to stimulate the expression of a cellular gene was investigated by using a transient-expression system. A plasmid in which the expression of the bacterial chloramphenicol acetyltransferase (cat) gene had been placed under the control of the DNA sequences that regulate the expression of the human beta-interferon gene was constructed. In Vero cells, cotransfection of the 2.7-kilobase BglII DNA fragment of HBV together with the test plasmid containing the cat gene resulted in stimulation of the expression of the cat gene. This HBV DNA fragment was specific in its trans-activation; no significant stimulation of CAT activity was observed in constructs when the promoter and enhancer elements were derived from the murine sarcoma viral long terminal repeat, Rous sarcoma virus, BK virus, or simian virus 40. Results of subcloning of the HBV DNA fragment indicate that the trans-activating function resides in a 944-base-pair EcoRV-BglII DNA fragment of the HBV genome that contains the X structural gene and its promoter element. Removal of the promoter from the X structural gene resulted in loss of the trans-activating function. A frameshift mutation within the X gene region also eliminated the trans-activating activity. These results suggest that the X antigen could play a role in HBV infections by activating the expression of cellular genes.