Biomedical subjects

G C Hall

Publications and source records attributed to G C Hall.

At least 19 recordsLinked to original sources

PubMed2004

Effectiveness of wet and dry mercury vapour suppressant systems in a faculty of dentistry clinic.

The objective of this study was to determine the effectiveness of a liquid and a dry commercial mercury vapour suppressant system. Measurements were made in a student dental clinic, using a mercury vapour detector for periods up to 76 weeks. The two products examined were Mercon vap liquid in a stock jar and the Mercon tainer dry jar system. Amalgam scrap jars were removed from the study when the mercury vapour concentration in the jars exceeded the arbitrary cut-off criterion of 0.05 mg Hg m(-3). Results showed that the mercury vapour concentration in the liquid system exceeded the cut-off criterion in 44 weeks or less, whereas the dry system remained below the detection limit (0.01 mg Hg m(-3)) for the maximum measurement period of 76 weeks. It was concluded that the dry system is more effective and reliable than the liquid system. The reliability of the liquid system may be influenced by contact of amalgam scrap with the portion of the inner wall of the jar that is not covered by liquid. It is proposed that amalgam scrap contaminates the wall with mercury during its insertion.

Air Pollution, Indoor↗

PubMed2001

Psychotherapy research with ethnic minorities: empirical, ethical, and conceptual issues.

There is an increasing demand for psychotherapy among ethnic minority populations. Yet, there is not adequate evidence that empirically supported therapies (ESTs) are effective with ethnic minorities. Ethical guidelines suggest that psychotherapies be modified to become culturally appropriate for ethnic minority persons. Conceptual approaches have identified interdependence, spirituality, and discrimination as considerations for culturally sensitive therapy (CST). However, there is no more empirical support for the efficacy of CSTs than there is for the efficacy of ESTs with ethnic minority populations. The chasm between EST and CST research is a function of differences between methods and researchers in these 2 traditions. Specific recommendations for research collaboration between CST and EST researchers are offered.

Cultural Diversity↗

PubMed2001

In search of cultural diversity: recent literature in cross-cultural and ethnic minority psychology.

The purpose of this study was to identify where the most work on cross-cultural and ethnic minority psychology is being published and who the most productive authors are. The journals that published the most articles on cross-cultural and ethnic minority issues from 1993 to 1999 and the most prolific authors on these issues were identified by PsycINFO. Cross-cultural research is cross-national, whereas ethnic minority research involves groups of color within the United States. The citation impact of these journals and authors was determined from the 1997 Social Sciences Citation Index. The results suggest that there is very limited overlap between the literatures in cross-cultural and ethnic minority psychology. Most of the research in these areas is published in specialty journals, and there is a paucity of this research in prestigious journals. Perceived or actual barriers to publication in prestigious journals may cause some to seek specialty journals as outlets for research on cultural diversity. The top scholars in cross-cultural psychology are primarily men of European ancestry, whereas most of the top scholars in ethnic minority psychology are ethnic minority men and women. Strategies to increase the prominence of cultural diversity in the psychology literature include combining cross-cultural and ethnic minority psychology, increasing the number of editorial board members of prestigious journals having expertise in cultural diversity, and increasing the quality of specialty journals. Psychology will remain ill-equipped to face the challenges of the new millennium without increased attention to cultural diversity.

Cultural Diversity↗

PubMed2000

Culture-specific models of men's sexual aggression: intra- and interpersonal determinants.

The role of intra- and interpersonal variables was examined in samples of Asian American (N = 91) and European American (N = 377) men. A path model for Asian American men suggested 2 interpersonal paths and 1 intrapersonal path to sexual aggression. For Asian Americans, concern about social standing is a risk factor among those who hold misogynous beliefs and who use alcohol before sex. Concern about the negative reputational impact of sexual aggression is a protective factor among Asian Americans who do not hold these negative attitudes. A European American model suggested only an intrapersonal path to sexual aggression consisting of misogynous beliefs, with interpersonal variables not being predictive of sexual aggression. These results suggest both individualist and collectivist determinants of Asian American sexual aggression, whereas only individualist determinants were found for European American sexual aggression.

Adult↗

PubMed2000

Considerations in measuring the electrical potentials of metallic restorations in vivo.

Many variables are believed to affect the accurate measuring of metallic restoration electrical potentials. This study examined the effects of intra- versus extra-oral location of the reference electrode, the type of metallic probe used to make contact with the restoration, and scratching and brushing of the restoration surface. Dental amalgam restorations were measured in 40 human subjects. Results showed that only the location of the reference electrode affected the central tendency of the potential. The study discusses the significance of some experimental variables in the accurate measuring of metallic potentials and the need to consider individual subject differences when statistically analysing for the central tendency of a sample.

Adult↗

PubMed2000

Effect of stepped light exposure on the volumetric polymerization shrinkage and bulk modulus of dental composites and an unfilled resin.

PURPOSE: To compare the volumetric polymerization shrinkage and dynamic bulk modulus of five resins and an experimental unfilled resin polymerized with a stepped power light and with a conventional one step curing light. MATERIALS AND METHODS: Parallel sided glass rings 5 mm in diameter and 2 mm high were etched for 5 min with hydrofluoric acid and silanated. The density and volume of the rings were calculated before they were filled with either SureFil, AEliteflo, Pertac II, Z100, or an experimental unfilled resin. When cured, the resin was bonded to the glass ring which produced a mold with a configuration C-factor of approximately 0.8. The resin was cured for 40 s on each side using either a one step curing light or a stepped power curing light. After curing, the specimens were weighed in air and in water to calculate their final density and volumetric shrinkage. Ten samples were made using each light system and for each resin (total of 100 samples). The bulk modulus was determined for each resin using an ultrasonic method, and the percentage filler contents were determined by thermogravimetric analysis. RESULTS: The mean +/- SD volumetric polymerization shrinkage values ranged from 3.10 +/- 1.19% for SureFil using the one step light to 12.35 +/- 1.38% for the unfilled resin using the stepped power curing light. Student-Newman-Keuls post hoc test separated the 10 different materials into three significant groups at P= 0.05. The unfilled resin exhibited the highest volumetric shrinkage followed by the flowable composite (AEliteflo). For all materials tested, there was no significant difference in the volumetric shrinkage values when the resin was cured with the one step or the stepped power curing light. There was no significant difference in the volumetric shrinkage values for the hybrid composites (Pertac II, Z100, and SureFil). The volumetric shrinkage values were highly sensitive to filler weight (P < 0.001). Except for Z100, there was no difference in the specific gravity values and velocities of the longitudinal and shear waves and bulk modulus when the one step and stepped power curing lights were used. The bulk modulus values ranged from 6.30 +/- 0.19 GPa for unfilled resin, to 17.10 +/- 1.09 GPa for Z100. Curing with the one step or the stepped curing light had no significant effect on the modulus values for any resin with the exception of Z100, P = 0.05. The bulk modulus values were highly sensitive to filler weight, and higher modulus values were associated with increased filler weight (P < 0.001). There was no significant difference between the bulk modulus of Pertac II and SureFil (P = 0.05).

Acid Etching, Dental↗

PubMed2000

Effect of stepped vs. continuous light curing exposure on bond strengths to dentin.

PURPOSE: To compare the 10-min and 24-hr shear bond strengths of three dentin bonding systems, polymerized with either a standard (Optilux 401) light for 60 s, or a stepped curing light (Elipar Highlight) that delivered a low light intensity for 10 s followed by high intensity for 50 s. MATERIALS AND METHODS: Three bonding systems were used to bond two resin-based composites (RBC) to dentin at 34 degrees +/- 2C using the two curing lights. Single Bond (SB) and Prime & Bond 2.1 (P&B) were used with Z100 RBC, and EBS bonding system was used with Pertac II RBC. Ten specimens from each combination were debonded at 37 degrees +/- 1C 10 min after starting to light cure the bonding system. Ten other specimens were stored in water at 37 degrees +/- 1C for 24 hrs before debonding at 37 degrees +/- 1C (total 120 teeth). RESULTS: The 10-min mean shear bond strengths were: Standard Cure; EBS 11.9 +/- 2.9 MPa, SB 14.6 +/- 2.2 MPa, P&B 14.7 +/- 4.2 MPa: Stepped Curing; EBS 7.4 +/- 2.1 MPa, SB 13.0 +/- 3.6 MPa, P&B 15.6 +/- 4.8 MPa. The 24-hr mean shear bond strengths were: Standard Cure; EBS 14.8 +/- 5.1 MPa, SB 25.1 +/- 3.3 MPa, P&B 25.2 +/- 8.8 MPa: Stepped Curing; EBS 15.1 +/- 4.6 MPa, SB 21.9 +/- 5.9 MPa, P&B 17.3 +/- 9.2 MPa. Three way ANOVA showed significant main effects for light, bonding system and time and no 2- or 3-way interaction effects at P = 0.01. The Least-Squares Means test with Sidak's adjustment for Multiple Comparisons showed that the bond strengths obtained using the standard light were significantly greater than the bond strengths obtained using the stepped curing light (P < 0.01). The 24-hr bond strengths were significantly greater (P < 0.01) than the 10-min bond strengths. The bond strengths obtained with EBS were significantly less than SB and P&B (P < 0.01), but there were no significant differences between SB and PB (P = 0.9752).

Adhesiveness↗

PubMed1999

Corrosion and cytotoxicity evaluation of thermafil endodontic obturator carriers.

The purpose of this study was to evaluate the in vitro cytotoxicity of two metallic and two plastic Thermafil carrier materials, and to separately evaluate the in vitro corrosion behavior of the two metallic carriers. Stainless-steel, Ti-6AI-4V, Polysulfone, and Vectra carriers were evaluated for cytotoxicity using the ISO-recommended agar overlay test. The two metallic carriers were additionally corrosion tested in 0.9% NaCl solution for 174 wk, at 37 degrees C. Elemental analyses of the corrosion solutions were periodically conducted using inductively coupled plasma-mass spectroscopy. Agar overlay results showed that the four carrier materials were not cytotoxic to L929 fibroblasts. Inductively coupled plasma-mass spectroscopy results showed that the metallic materials had small mass loss rates. Scanning electron microscopy showed no evidence of pitting or crevice corrosion.

Alloys↗

PubMed1999

In vitro comparison of 10-minute versus 24-hour shear bond strengths of six dentin bonding systems.

OBJECTIVE: Early bond strengths produced by dentin bonding systems should be sufficient to resist the polymerization shrinkage of resin composite. This study compared the 10-minute and 24-hour shear bond strengths of six dentin bonding systems: One-Step (OS), PermaQuik (PQ), Prime & Bond 2.1 (PB), Scotchbond Multi-Purpose (SBMP), Single Bond (SB), and Tenure Quik with Fluoride (TQ). METHOD AND MATERIALS: Each bonding system was used to bond composite to visibly moist dentin at 34 degrees C +/- 2 degrees C. The specimens were debonded at 37 degrees C +/- 1 degree C 10 minutes after the start of light curing of the bonding system, and the results were compared with the 24-hour bond strengths. The mode of failure was recorded. RESULTS: The 10-minute mean shear bond strengths were: OS, 16.4; PQ, 14.3; SB, 14.0; PB, 12.7; TQ, 10.7; and SBMP, 9.3 MPa. The 24-hour mean shear bond strengths were OS, 23.3; PB, 20.8; SB, 20.3; PQ, 19.4; TQ, 11.2; and SBMP, 10.0 MPa. The 10-minute mean shear bond strengths of OS, PQ, PB, and SB bonding systems were significantly less than the 24-hour values. More dentinal fractures and mixed failures were observed with OS, PQ, and PB. Systems with higher bond strengths had more resin penetration into the lateral dentinal branches. CONCLUSION: The 10-minute mean shear bond strengths were all less than 17 MPa, and the 10-minute bond strengths were less than the 24-hour values.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1998

Sexual aggression among Asian Americans: risk and protective factors.

Rates of sexual aggression among Asian Americans are relatively low. It is possible that these low rates are because Asian Americans are less likely than other groups to develop developmental, motivational, and situational risk factors associated with sexual aggression. Moreover, an emphasis in Asian cultures on self-control of sexual and aggressive behavior may serve as a protective factor. Nevertheless, patriarchal aspects of Asian cultures may place some Asian Americans at risk for sexual victimization or perpetration of sexually aggressive behavior. Although Asian Americans may be at less risk for sexual aggression than other groups, interventions that counteract the patriarchal aspects of Asian cultures may further reduce risk.

Aggression↗

PubMed1997

Prevention of sexual aggression: Sociocultural risk and protective factors.

Physiological, cognitive, affective, and developmental sociocultural risk factors for perpetrating sexual aggression are identified. Feminine and multicultural socialization may serve as protective factors against these risk factors because both forms of socialization emphasize empathy and sexuality in the context of committed relationships. It is proposed that feminist and multicultural education across the developmental span may constitute methods of reducing and preventing the development of sexually aggressive behavior. However, feminist and multicultural approaches may have limited impact without greater acceptance within societal power structures, including psychology. The authors call for psychologists interested in reducing sexually aggressive behavior to become better informed and experienced with feminist and multicultural approaches. They also suggest that it may be time for all persons in society to become competent in multiple domains.

Aggression↗

PubMed1996

Crystallization of experimental bioactive glass compositions.

Crystallization kinetics studies for six experimental glass formulations in the system Na2O-CaO-SiO2-P2O5 synthesized by wet chemistry were conducted by means of differential thermal analysis. These glasses had CaO/P2O5 and SiO2/ (CaO + Na2O) ratios ranging from 8.74-3.38 and 0.92-3.03, respectively. Samples of each glass (n = 30 were heated from 23 to 1250 degrees C under N2 atmosphere at heating rates ranging from 10 to 50 degrees C/min. Glass-ceramics were obtained after heat treating the initial glasses at temperatures determined from their DTA exotherms. The activation energy of crystallization for each glass composition was calculated from an expression-relating log-heating rate and the reciprocal of the exothermic peak temperature. The compositions of the six glasses were significantly different (p = 0.05). The activation energy of crystallization (Q) values ranged from 196 to 782 kJ/mole. A correlation was obtained between Q and CaO/P2O5 and between Q and the Young's modulus (P < 0.001). Two of the six glasses exhibited bulk crystallization. X-ray diffraction studies showed that four of the six glasses exhibited different proportions of crystalline phases following heat treatment. These phases were wollastonite (CaSiO3), Na2CaSi3O9, combeite [Na4Ca3SI6O16(OH)2], and some unidentifiable phases. Two of the six bioceramic materials had a mixture of unknown crystalline phases.

Biocompatible Materials↗

PubMed1995

Sexual offender recidivism revisited: a meta-analysis of recent treatment studies.

Meta-analyses were performed on 12 studies of treatment with sexual offenders (N = 1,313). A small, but robust, overall effect size was found for treatment versus comparison conditions (r = .12). The overall recidivism rate for treated sexual offenders was .19 versus .27 for untreated sexual offenders. Treatment effect sizes across studies, however, were heterogeneous. Effect sizes were larger in studies that had higher base rates of recidivism, had follow-up periods longer than 5 years, included outpatients, and involved cognitive-behavioral or hormonal treatments. Cognitive-behavioral (p < .0005) and hormonal treatments (p < .00005) were significantly more effective than behavioral treatments but were not significantly different from each other.

Androgen Antagonists↗

PubMed1994

The relationship between men's sexual aggression inside and outside the laboratory.

The purpose of this study was to develop a laboratory analogue of sexually aggressive behavior. Subjects viewed neutral, sexual-violent, and violent-sexual film vignettes and chose a vignette to show to a female confederate. Among highly sexually aggressive men (n = 25) according to the Coercive Sexuality Scale (CSS; Rapaport & Burkhart, 1984), 24% showed the sexual-violent vignette and 28% showed the violent-sexual vignette. Among men who did not report being sexually aggressive on the CSS (n = 13), none showed the sexual-violent vignette and only one showed the violent-sexual vignette. The between-group difference in vignette showing was statistically significant (p < .024). Subjects who showed the sexually aggressive vignettes reported that the female confederate was upset (p < .0001) and uncomfortable (p < .0001) in viewing these vignettes more than the subjects did who showed the neutral vignette. These results support the validity of this film-showing procedure as a laboratory analogue of sexually aggressive behavior.

Adult↗

PubMed1994

Now what?

Explore the source record for details and available documents.

Alabama↗

PubMed1993

The role of sexual arousal in sexually aggressive behavior: a meta-analysis.

Meta-analyses were performed on 9 studies of subjects' (N = 434) penile responsivity to rape stimuli. The mean effect size for raw score data suggested that most sexual aggressors against women exhibit slightly more rape arousal than control or comparison subjects, whereas the mean effect size for rape index (rape arousal:consenting sexual arousal) data suggested a moderate between-groups difference. Rape index effect sizes in individual studies, however, were heterogeneous. The rape index appears sensitive to differences between sexually aggressive men and those who are not but is not sensitive to differences between men who sexually aggress against women versus other types of sexual aggressors. Also discussed are the needs for standardization and methodological and statistical improvements.

Aggression↗

PubMed1992

MMPI taxonomies of child sexual and nonsexual offenders: a cross-validation and extension.

In a court clinic sample of 107 child sexual and nonsexual offenders, Minnesota Multiphasic Personality Inventory (MMPI) profiles did not differ as a function of arrests for sexual versus nonsexual offending. However, a three-group cluster-analytic solution was generated. Two of these clusters replicated those derived by Hall, Graham, and Shepherd (1991). The first cluster was unelevated, with Scales 4 and 9 as high points. The second cluster had MMPI Scales 4, 8, 2, and 7 as the highest scales. The third cluster was even more elevated than the other two clusters, characterized by extreme elevations on MMPI Scales F, 2, 4, 6, 7, and 8. The somewhat different results of this study versus previous studies (e.g., Hall et al., 1991) may be a function of the different populations sampled. The results provide evidence of within-group heterogeneity among sexual and nonsexual offenders that may be as important as between-group differences.

Adult↗

PubMed1991

Sexual arousal as a function of physiological and cognitive variables in a sexual offender population.

Physiological and cognitive variables may compromise the physiological assessment of sexual arousal, particularly in forensic settings. Thus, the effects of physiological and cognitive variables as potential moderators need investigation with respect to physiological measures of sexual arousal. Penile erection, demographic, and psychometric data were analyzed among 169 inpatients adult male sexual offenders. The hypotheses that (i) sexual arousability would be inversely related to age and (ii) subjects who were able to cognitively inhibit their sexual arousal would exhibit lower levels of pedophilic arousal than subjects who were unable to inhibit arousal were supported. Subject age did not interact with inhibition ability. Age and the presence of inhibitory ability appear to be arousability variables in that these variables mediate both deviant and nondeviant arousal.

Adult↗