Showing papers by "University of Illinois at Chicago published in 1984"

Stability of Aggression Over Time and Generations.

Abstract: This study was supported in part by Grant MH-34410 to Leonard D. Eron from the National Institute of Mental Health.

Preliminary Studies of the Reliability and Validity of the Children's Depression Rating Scale

Abstract: The Children's Depression Rating Scale, revised version (CDRS-R), is a reliable, clinician-rated scale which differentiates the depressed from the nondepressed child. The sum score of the CDRS-R appears to provide a better estimate of depressive symptomatology than does clinical impression. The relationship of the sum of the CDRS-R with global clinical ratings of depression indicates that the scale measures the severity of depression which is its primary purpose. The scale is not affected by the age of the child in our clinical sample, and the content of the items grouped as mood, somatic, subjective, and behavior all show good correlations with depression. The CDRS-R has been shown to be useful in a variety of settings, suggesting it is useful in both primary and secondary depressions.

Multiple Evanescent White Dot Syndrome: I. Clinical Findings

Abstract: • We examined 11 young patients with unilateral ocular findings that included multiple white dots at the level of the retinal pigment epithelium (RPE) or the deep retina, vitreal cells, RPE granularity in the macula, reduced visual acuity, electroretinogram (ERG) and early receptor potential (ERP) amplitudes, and fluorescein leakage from disc capillaries and late staining of the RPE. Recovery of visual function included a dramatic improvement in ERG and ERP amplitudes over several weeks. The etiology of this syndrome remains uncertain; there is no definite evidence of systemic involvement.

The Effects of Homework on Learning: A Quantitative Synthesis

Abstract: This paper synthesizes empirical studies of homework and of various homework strategies on the academic achievement and attitude of elementary and secondary students. A computer search yielded 15 p...

The emergence and consolidation of self-control from eighteen to thirty months of age: normative trends and individual differences.

Abstract: This study is a descriptive report of the capability to exercise self-control in very young children. 2 aspects of self-control were assessed (delay/response inhibition in the presence of an attractive stimulus and compliance with maternal directives in a cleanup task) for 72 children between the ages of 18 and 30 months. The results indicated that both aspects of self-control show age-related increases. However, a factor analysis of the behaviors observed in the cleanup task suggested that compliance could not be adequately described with a unitary, bipolar dimension (noncompliance vs. compliance). 2 patterns of non-compliance were observed, and 1 of these also increased with age. Cross-task consistency for the delay measures) and coherence across the 2 aspects of self-control showed a positive relationship with increasing age. Finally, correlational analyses of the self-control measures and developmental test data showed that individual differences in self-control were associated with differences in cognitive-developmental status (DA). The results are interpreted as evidence that the achievement of self-control can be considered as a major developmental accomplishment and as evidence that individual differences in self-control emerge and are consolidated during the second and third years of life.

Bioactivities, Estrogen Receptor Interactions, and Plasminogen Activator-inducing Activities of Tamoxifen and Hydroxy-tamoxifen Isomers in MCF-7 Human Breast Cancer Cells

Abstract: Tamoxifen is used widely in the treatment of endocrine-responsive breast cancers in humans. Studies were undertaken to examine the biological character (estrogenic-antiestrogenic properties) and estrogen receptor (ER) interaction of the cis- and trans-isomers of tamoxifen and hydroxytamoxifen in MCF-7 human breast cancer cells. For each compound, the following parameters were monitored: affinity for ER and effects on cellular ER levels; stimulation-inhibition of cell growth, plasminogen activator activity, and cellular progesterone receptor levels; and isomer interconversion and metabolism in vitro. The relative binding affinities of the compounds cis-tamoxifen, trans-tamoxifen, cis-hydroxytamoxifen, and trans-hydroxytamoxifen for cytosol ER were 0.3, 2.5, 1.8, and 310%, respectively, in which the affinity of estradiol is considered 100%. cis-Tamoxifen behaved as a weak estrogen agonist in all assays, while trans-tamoxifen was an effective estrogen antagonist. cis-Tamoxifen behaved like estradiol in stimulating MCF-7 cell growth and increasing plasminogen activator activity and cellular progesterone receptor content, although very much higher concentrations of cis-tamoxifen (10(-6) M) were needed to achieve the levels of stimulation observed with 10(-10) M estradiol. trans-Tamoxifen and trans-hydroxytamoxifen suppressed cell growth, inhibited plasminogen activator activity of control cells, and suppressed estradiol-stimulation of plasminogen activator activity, and they evoked minimal increases in cellular progesterone receptor levels. trans-Hydroxytamoxifen had a 100-fold increased affinity for ER and was approximately 100-times more potent than was trans-tamoxifen in suppressing cell growth and plasminogen activator activity. cis-Hydroxytamoxifen behaved as an estrogen antagonist, suppressing cell growth and plasminogen activator activity, and it elicited submaximal increases in progesterone receptor levels. This apparently paradoxical behavior of cis-hydroxytamoxifen was shown to be due to the fact that the cis- and trans-hydroxytamoxifens readily undergo isomeric interconversion upon exposure to our cell culture conditions, resulting in substantial accumulation of the higher-affinity trans-hydroxytamoxifen in the nuclear ER fraction of cells. In contrast to the facile interconversion of the hydroxytamoxifen isomers, there is no metabolism or interconversion of the parent compounds cis- and trans-tamoxifen in vitro. Hence, by the criteria we have used, the biological characters of trans-tamoxifen and trans-hydroxytamoxifen are similar, the major difference being the approximately 100-fold enhanced potency of the hydroxylated form. In contrast, cis-t

Cloning of genes controlling alginate biosynthesis from a mucoid cystic fibrosis isolate of Pseudomonas aeruginosa.

Abstract: Mucoid strains of Pseudomonas aeruginosa isolated from the sputum of cystic fibrosis patients produce copious quantities of an exopolysaccharide known as alginic acid. Since clinical isolates of the mucoid variants are unstable with respect to alginate synthesis and revert spontaneously to the more typical nonmucoid phenotype, it has been difficult to isolate individual structural gene mutants defective in alginate synthesis. The cloning of the genes controlling alginate synthesis has been facilitated by the isolation of a stable alginate-producing strain, 8830. The stable mucoid strain was mutagenized with ethyl methanesulfonate to obtain various mutants defective in alginate biosynthesis. Several nonmucoid (Alg-) mutants were isolated. A mucoid P. aeruginosa gene library was then constructed, using a cosmid cloning vector. DNA isolated from the stable mucoid strain 8830 was partially digested with the restriction endonuclease HindIII and ligated to the HindIII site of the broad host range cosmid vector, pCP13. After packaging in lambda particles, the recombinant DNA was introduced via transfection into Escherichia coli AC80. The clone bank was mated (en masse) from E. coli into various P. aeruginosa 8830 nonmucoid mutants with the help of pRK2013, which provided donor functions in trans, and tetracycline-resistant exconjugants were screened for the ability to form mucoid colonies. Three recombinant plasmids, pAD1, pAD2, and pAD3, containing DNA inserts of 20, 9.5, and 6.2 kilobases, respectively, were isolated based on their ability to restore alginate synthesis in various strain 8830 nonmucoid (Alg-) mutants. Mutants have been assigned to at least four complementation groups, based on complementation by pAD1, pAD2, or pAD3 or by none of them. Introduction of pAD1 into the spontaneous nonmucoid strain 8822, as well as into other nonmucoid laboratory strains of P. aeruginosa such as PAO and SB1, was found to slowly induce alginate synthesis. This alginate-inducing ability was found to reside on a 7.5-kilobase EcoRI fragment that complemented the alg-22 mutation of strain 8852. The pAD1 chromosomal insert which complements the alg-22 mutation was subsequently mapped at ca. 19 min of the P. aeruginosa PAO chromosome. Images

Distributed query processing

Abstract: On presente plusieurs techniques d'optimisation des questions au sein d'un reseau de bases de donnees. Les caracteristiques d'un algorithme integrant ces techniques sont enoncees

Psychometric assessment of the Jalowiec Coping Scale.

Abstract: The Jalowiec Coping Scale consists of 40 coping behaviors culled from a comprehensive literature review, which are rated on a 1- to 5-point scale to indicate degree of use. Twenty judges classified the items to permit analysis of the coping behaviors according to a problem-oriented/affective-oriented dichotomy; 15 problem and 25 affective items resulted. Overall agreement by the judges was 85%, with greater consensus on problem items. Evaluation of stability using a two-week retest interval (N = 28) yielded significant rhos of .79 for total coping scores, .85 for problem, and .86 for affective. With a one-month interval (N = 30) coefficients were .78, .84, and .83, respectively. Alpha reliability coefficients of .86 (N = 141) and .85 (N = 150) supported instrument homogeneity. Content validity is substantiated by the systematic manner of tool development, by the large number of items used, and by the inclusion of diverse coping behaviors. Factor analysis (N = 141) was used to investigate construct validity. A two-factor solution to evaluate the validity of the dichotomous classification showed that 80% of the problem items loaded on Factor I, but only 56% of the affective items loaded on Factor II. To examine this multidimensional aspect, several other factor solutions were explored. Ultimately, the four-factor solution provided the most intelligible conceptual pattern with the least loss of information. Conceptual composition of these factors is discussed, and several tentative labels for each factor are suggested.

Adenosine analogs and sleep in rats.

Abstract: The effects of N6-L-(phenylisopropyl)adenosine, cyclohexyladenosine and adenosine-5'-N-ethylcarboxamide on sleep were examined in rats. These effects consist of 1) increased slow-wave sleep2 from 6.6 to 45.7%, in all doses used for cyclohexyladenosine and adenosine-5'-N-ethylcarboxamide and for 0.1 and 0.3 mumol/kg of N6-L-(phenylisopropyl)adenosine and 2) increased values for rapid-eye-movement-sleep, amounting to 56.2 and 51.6% for 0.1 mumol/kg of cyclohexyl-adenosine and 0.3 mumol/kg of N6-L-(phenylisopropyl)adenosine, respectively. Slow-wave sleep1 decreased but values for wakefulness and total sleep were unchanged for 0.03, 0.1 and 0.3-mumol/kg doses of the drugs. Only 0.9-mumol/kg dose of cyclohexyladenosine and N6-L-(phenylisopropyl)adenosine increased wakefulness and decreased total sleep, whereas the same dose of adenosine-5'-N-ethylcarboxamide increased total sleep during the 0- to 3-hr time interval. All three agents reduced rapid-eye-movement sleep at the 0.9-mumol/kg dose. The results indicate that the effect on sleep of all three adenosine analogs was obtained with nanomolar doses of the drugs and that it diminished or disappeared when the drug dose reached micromolar range (0.9 mumol/kg). It appears, therefore, that activation of A1 rather than A2 receptors contributed to the sleep effects of the drugs because adenosine and adenosine analogs activate A1 receptors in nanomolar quantities whereas activation of A2 receptors requires micromolar concentration of these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Intervening Variables in the TV Violence-Aggression Relation: Evidence from Two Countries.

Abstract: s research was supported in part by Grants MH- 28280 and MH-3I886 from the National Institute of Mental Health to L. Rowell Huesmann, and by grants from the Council of Social Sciences, Academy of Finland (Valtion Yhteiskuntatieteelhnen Toimikunta, Suomen Akatemia) to Kirsti Lagerspetz.

Theoretical contributions: A five-stage model of intergroup relations

Abstract: This paper outlines a five-stage model of intergroup relations that attempts to specify the responses of disadvantaged and advantaged groups to inequality. It is proposed that at Stage 1 stratification is based solely on group membership resulting in a rigid dominant–subordinate relationship between groups. At Stage 2 stratification is believed to be based on individual achievement. At Stage 3 certain members of the disadvantaged group attempt to pass into the advantaged group. Stage 4 emerges as those who are unsuccessful in their attempt to pass engage in consciousness raising. Specifically, they attempt to persuade all members of the disadvantaged group that their status is collectively defined and illegitimate. At Stage 5 the disadvantaged group competes directly with the advantaged group. It is hypothesized that the basic processes of causal attribution and social comparison both underlie each stage and control the transition between the stages.

Homologous recombination between plasmids in mammalian cells can be enhanced by treatment of input DNA.

Abstract: We have used the eukaryotic-prokaryotic shuttle vector pSV2Neo to demonstrate that cultured mammalian somatic cells have the enzymatic machinery to mediate homologous recombination and that the frequency of this recombination can be enhanced by pretreatment of the input DNA. Two nonoverlapping deletion mutants of pSV2Neo were constructed, each affecting the bacterial aminoglycoside 3'-phosphorylase gene (the neo gene), which confers resistance to aminoglycoside antibiotics on bacteria and resistance to the antibiotic G418 on mammalian cells. Mammalian cells transfected with either deletion plasmid alone yield no G418 -resistant colonies. Cells cotransfected with both deletion plasmids yield G418 -resistant colonies with high frequency. We show that these resistant colonies result from recombination involving homologous crossing-over or gene conversion between the deletion plasmids by rescuing from the resistant cells both types of reciprocal recombinant, full-length plasmids, and doubly deleted plasmids. Cutting one of the input plasmids to generate a double-stranded gap in the neo gene considerably enhances the frequency of homologous recombination within the gene. This suggests that targeting exogenous DNA to specific sites in mammalian chromosomes could be facilitated by suitable pretreatment of the DNA.

The Genus Chrysomya (Diptera: Calliphoridae) in the New World

Abstract: Four Chrysomya species have recently become established in the Americas and are spreading rapidly. Chrysomya albiceps and C. putoria (= C. chloropyga form putoria ) in Peru, C. putoria in Colombia, are reported for the first time. Previously unrecognized specimens of Chrysomya taken in South America in the late 1800's and in 1961 in Puerto Rico are proof of past unsuccessful introductions. Estimated maximum dispersal rates for C. rufifacies (3.2 km/day) and C. albiceps and C. putoria (1.8 km/day), enhanced by their hitchhiking habits and synanthropy, account for their rapid spread in South America. On the eastern slope of the Peruvian Andes, C. putoria occurs mainly below 1000 m, while C. albiceps flourishes from 1000 to 3100 m in areas with an annual median temperature range of 11–23 °C. Data are presented on synanthropy, endophily, and bait preferences for C. putoria and C. albiceps in Peru. Sampling the same Peruvian localities in 1977, 1980, and 1981 has demonstrated that Cochliomyia macellaria is suppressed as populations of C. putoria and C. albiceps increase. At 1000 m, near San Ramon, where C. putoria and C. albiceps are equally numerous, Co. macellaria plummeted in 18 months from 89 to 0.2% of the total blow fly population. At 200 m, near Pto. Bermudez, where C. albiceps is rare, Co. macellaria suppresssion has been less severe (45.5 to 1 1.3%). Bionomic and other factors favoring displacement of Co. macellaria are discussed.

Honesty testing for personnel selection: a review and critique

Abstract: Paper and pencil predictors of employee theft are described and studies of validity, reliability, and adverse impact of these tests are examined. Validity studies for 10 tests were grouped into 5 categories: comparisons with polygraph examination results, correlations with admissions of past theft, predictive studies using future job behaviors as criteria, comparisons of shrinkage rates before and after the introduction of a testing program, and comparisons of test scores of groups known to be dishonest with groups representing the general population. While positive correlations were consistently found, a variety of methodological differences between studies were identified which make the direct comparison of test validities suspect. High reliabilities are consistently reported, and test score comparisons by race and sex generally report no differences. Ethical issues in honesty test usage are considered and future research needs are identified.

Cognitive processes and the persistence of aggressive behavior

Abstract: Recent data from several longitudinal studies including one spanning 22 years suggest that aggression is quite stable over time and situation. Early measures of intellectual competence predicted concurrent and later aggression, but early aggression was independently a good predictor of reduced intellectual achievement as an adult. Over a shorter period of years cognitive rehearsal of aggressive behaviors predicted overt aggression, was predicted by overt aggression, and correlated with the child's TV viewing. In combination, these data suggest a circular process in which scripts for aggressive behavior are learned at an early age and become more firmly entrenched as the child develops, so that aggression becomes self-perpetuating in children with certain cognitive characteristics.

Perianal abscesses and fistulas. A study of 1023 patients.

Abstract: In a five and one-half year period, 1023 patients with anorectal abscesses and fistulas were treated. Under regional anesthesia the abscesses were unroofed and debrided and a primary fistulotomy was performed whenever a low fistula was identified. In 355 (34.7 per cent) an internal fistulous opening was demonstrated at the time of abscess drainage. Thirty-two patients had suprashincteric fistulas and underwent two-stage fistulotomy using a seton. Perianal abscesses were encountered in 42.7 per cent of the patients, followed by ischiorectal (22.7 per cent), intersphincteric (21.4 per cent), and supralevator (7.33 per cent). The patients with supralevator and intersphincteric abscesses had a high incidence of fistula identified during abscess drainage. The recurrence rates were 3.7 per cent in the group with abscess drainage only and 1.8 per cent in the group that had primary fistulotomy along with abscess drainage. The follow-up period averaged 36 months. To accomplish adequate drainage and identify the deeper components and associated fistulous opening (34.7 per cent of the entire group), careful examination under regional anesthesia is recommended. Early aggressive treatment of an anorectal abscess and fistula significantly reduces the possibility of recurrent abscesses and/or the need for further surgery.

You're Only as Pretty as You Feel: Facial Expression as a Determinant of Physical Attractiveness

Abstract: Photos of IS target persons posing happy, neutral, and sad facial expressions were rated for facial attractiveness using paired comparisons and Likert scales. Half the raters were instructed to compensate for the effects of facial expression. Paired comparisons and Likert ratings were highly correlated. Target persons were less attractive when posing sad expressions than when posing neutral or happy expressions, which did not differ. No effect of compensation instructions was found. In addition, independent ratings of four dimensions of the target persons' facial expression were obtained: pleasantness, surprise, intensity, and naturalness. Changes in these dimensions from the neutral to the happy and sad expressions and the corresponding changes in attractiveness were consistently related only to pleasantness supporting the reinforcement-affect theory of attraction. A second study related overall attractiveness to facial and bodily attractiveness. Both facial and bodily attractiveness were predictive of overall attractiveness, but the face was a slightly more powerful predictor. Results are discussed with respect to the stability of physical attractiveness, and alternative explanations of the mental-illness/physicalunattractiveness relation were proposed.

A topological approach to evasiveness

Abstract: The complexity of a digraph property is the number of entries of the vertex adjacency matrix of a digraph which must be examined in worst case to determine whether the graph has the property Rivest and Vuillemin proved the result (conjectured by Aanderaa and Rosenberg) that every graph property that is monotone (preserved by addition of edges) and nontrivial (holds for some but not all graphs) has complexity Ω(v 2) wherev is the number of vertices Karp conjectured that every such property is evasive, ie, requires that every entry of the incidence matrix be examined In this paper the truth of Karp’s conjecture is shown to follow from another conjecture concerning group actions on topological spaces A special case of the conjecture is proved which is applied to prove Karp’s conjecture for the case of properties of graphs on a prime power number of vertices

Psychological factors associated with primary fibromyalgia syndrome.

Abstract: Forty-five ambulatory patients with primary fibromyalgia syndrome (PFS), 30 with rheumatoid arthritis, and 32 normal controls were administered 3 psychological tests: the Minnesota Multiphasic Personality Inventory (MMPI), the Life Events Inventory, and the Assertiveness-Aggressiveness Inventory. The PFS patients scored significantly higher on 8 MMPI scales when compared with the normal control group and on 4 MMPI scales when compared with the rheumatoid arthritis group. Further subgrouping of PFS patients according to MMPI scores showed that only 31% were "psychologically disturbed," 33% had a typical chronic pain profile, and 36% were within the normal range. The PFS patients scored higher than the rheumatoid arthritis and normal control groups on the Life Events Inventory but not the Assertiveness-Aggressiveness Inventory.

Selective necrosis and total necrosis in focal cerebral ischemia. Neuropathologic observations on experimental middle cerebral artery occlusion in the macaque monkey.

Abstract: Temporary (15 minutes to 24 hours) or permanent focal cerebral ischemia was induced in 87 awake monkeys (Macaca mulatta and Macaca fasicularis) by transorbital snare ligation of the middle cerebral artery (MCA) and neuropathological evaluation was carried out two weeks later. The size, location and histology of lesions varied within each time-period of MCA occlusion. However, most animals that underwent long-term ischemia (eight hours to permanent) had a single, confluent infarct involving deep and sometimes cortical structures. These animals had total necrosis chracterized by: 1. indiscriminate involvement of white and gray matter, 2. relatively sharp margins containing astrocytic and mononuclear cells, 3. an inner zone of liquefaction, infiltrated with fat-laden macrophages and newly formed blood vessels. Animals that underwent moderate to short-term ischemia (30 minutes to four hours) showed multiple, non-confluent deep infarcts. These animals had selective necrosis characterized by: 1. involvement of gray matter and relative sparing of white matter, 2. poorly circumscribed, multiple and often perivascular lesions with incomplete tissue destruction, 3. preferential loss of neurons and proliferation of reactive astrocytes and microglia.

Energy Eigenstates of Spherically Symmetric Potentials Using the Shifted 1/$N$ Expansion

Abstract: We show that an excellent analytic approximation to the energy eigenvalues and eigenfunctions of the Schr\"odinger equation can be obtained using the shifted $\frac{1}{N}$ expansion, where $N$ is the number of spatial dimensions. This technique, which was physically motivated for power-law potentials, is extended in this paper to general spherically symmetric potentials. The calculations are carried out for states with arbitrary quantum numbers $n$ and $l$ using fourth-order perturbation theory in the shifted expansion parameter $\frac{1}{\overline{k}}$, where $\overline{k}=N+2l\ensuremath{-}a$. We obtain very accurate agreement with numerical results for a variety of potentials for a very large range of both $n$ and $l$. Our results using the shift $a$ are consistently better than those previously obtained using the unshifted expansion parameter $\frac{1}{k}$, $k=N+2l$. The shifted $\frac{1}{N}$ expansion is seen to be applicable to a much wider class of problems than are most other approximation methods.

Ontogenetic changes in frequency mapping of a mammalian ear

Abstract: Cochlear microphonic iso-response functions reported here suggest an explanation of frequency-dependent changes in hearing sensitivity during early development. The work is a direct demonstration of developmental changes in the spatial frequency map of the mammalian hearing organ. Intracochlear recordings from the midbasal turn in a series of age-graded gerbils reveal a progressive increase in best frequency, spanning approximately two octaves, from the time of onset of function until adultlike responses are seen. It is, therefore, suggested that ontogenetic changes in the cellular structure of the organ of Corti contribute to an age-dependent shift in micromechanical response.

The effects of pollen composition on fitness components in a neotropical herb.

Abstract: Experimental pollinations of Costus allenii (Zingiberaceae) were conducted to assess the effects of pollen composition on fitness. Plants were selfed, outcrossed with the first nearest neighbor, and outcrossed with pollen mixtures obtained from the nearest 2, 3, and 5 plants. Cross type had a significant effect on seed production, seed weight and total-plant dry weight. Progeny from crosses with 3, and 5 parents grew significantly larger than selfed progeny, or those from 1-parent crosses. Competition experiments indicated the superiority of progeny from 3-, and 5-parent crosses over progeny from 1-parent crosses, but no differences in competitive ability were observed between progeny from 3-, and 5-parent crosses. Relative fitness, based on 1) seed production, 2) percent germination, and 3) dry weight, varied significantly among crosses, and was greatest for crosses with 3 parents and lowest for selfs. The relative fitness of progeny from 5-parent crosses was lower than that of all other outcrossed classes. We suggest that the significant effect of pollen composition on fitness results from variation in the genetic similarity of seed and pollen parents, which is a function of spatial distribution and population structure.

William River: An outstanding example of channel widening and braiding caused by bed-load addition

Abstract: The lower William River in northwestern Saskatchewan, Canada, presents an excellent and unambiguous example of rapid channel adjustment to abrupt additions of sandy bed load. A relatively narrow and deep single-channel stream as it flows northward to Lake Athabasca, the river picks up a 40-fold increase of bed load over a 27-km reach as it encounters a large dune field just south of the lake. As a result of the large infusion of eolian sand, the channel develops a thoroughly braided pattern while undergoing a 5-fold increase in width and a 10-fold increase in width/depth ratio.

Effect of diagnostic criteria on the ratio of male to female schizophrenic patients.

Abstract: Contrary to earlier epidemiological data, recent evidence points to a significantly greater proportion of men than women among schizophrenic patients diagnosed by current restrictive criteria. In this study, the authors analyzed the effect of using six different diagnostic systems (varying in their stringency) on the male to female ratio of schizophrenia among 387 inpatients. Diagnostic criteria representing a broad conceptualization of schizophrenia, such as the New Haven Schizophrenia Index, consistently yielded equal rates of schizophrenia among men and women. Those diagnostic systems representing more stringently defined schizophrenia, such as the Research Diagnostic Criteria, consistently yielded a male to female ratio significantly greater than the male to female ratio of the total sample.