Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas.

Observations of improved radio frequency (rf) heating efficiency in ITER relevant high-confinement (H-)mode plasmas on the National Spherical Tokamak Experiment are investigated by whole-device linear simulation. The steady-state rf electric field is calculated for various antenna spectra and the results examined for characteristics that correlate with observations of improved or reduced rf heating efficiency. We find that launching toroidal wave numbers that give fast-wave propagation in the scrape-off plasma excites large amplitude (∼kV m(-1)) coaxial standing modes between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggests that these modes are a probable cause of degraded heating efficiency.

Sheared poloidal flow driven by mode conversion in tokamak plasmas.

A two-dimensional integral full-wave model is used to calculate poloidal forces driven by mode conversion in tokamak plasmas. In the presence of a poloidal magnetic field, mode conversion near the ion-ion hybrid resonance is dominated by a transition from the fast magnetosonic wave to the slow ion cyclotron wave. The poloidal field generates strong variations in the parallel wave spectrum that cause wave damping in a narrow layer near the mode conversion surface. The resulting poloidal forces in this layer drive sheared poloidal flows comparable to those in direct launch ion Bernstein wave experiments.

High-beta equilibria of drift-optimized compact stellarators.

Compact stellarator configurations have been obtained with good neoclassical confinement that are stable to both pressure- and current-driven modes for high values of beta. These configurations are drift-optimized tokamak-stellarator hybrids with a high-shear tokamak-like rotational transform profile and /B/ that is approximately poloidally symmetric. The bootstrap current is consistent with the required equilibrium current and, while larger than that in existing stellarators, is typically only a small fraction (1/3-1/5) of that in an equivalent tokamak. These configurations have strong magnetic wells and consequently high interchange stability beta limits up to beta=23%. Because of the reduced bootstrap current, these configurations are stable to low-n ideal MHD kink modes with no wall stabilization for values of beta ( approximately 7%-11%) significantly larger than in an equivalent advanced tokamak.

Personality attributions based on speech samples of children with repaired cleft palates.

OBJECTIVE: This study examined whether or not assumptions made about personality characteristics based on speech samples differed for children with repaired cleft palates (CP) versus unaffected children. DESIGN: Audiotapes of speech samples were presented in random order to blind raters. PATIENTS/PARTICIPANTS: The subjects were 20 children (10 females, 10 males) with repaired CP and 16 control (i.e., unaffected) children (8 females, 8 males). All children were 8 to 12 years of age, Caucasian, living in the St. Louis area, and lower-middle to upper-middle class. The raters were 20 (13 females, 7 males) 6th grade Caucasian students who attend a private school in the area. SETTING: Raters heard tapes in a group setting, but with individual headphones, in their school's cafeteria. MAIN OUTCOME MEASURE: Each speech sample was rated (7-point Likert scale) by each student rater on a variety of personality characteristics based on the "Big Five" personality factors. RESULTS: A factor analysis of the items revealed a two-factor solution, although the factors were highly negatively correlated. No significant differences were found between ratings for the CP sample and the control sample for either factor scale (ANOVA, p = .93; p = .67). Similarly, when the two factors were combined to form a single factor, no significant differences were found between the ratings for the CP sample and the control sample (ANOVA, p = .79). CONCLUSIONS: Overall, it does not appear that children differentially associated personality characteristics based on speech to children with repaired CP versus unaffected children, in the absence of visual input.

Speech outcome following palatoplasty in primary school children: do lay peer observers agree with speech pathologists?

The aim of this study was twofold: (1) to test the ability of normal children to discriminate the speech of children with repaired cleft palate from the speech of unaffected peers and (2) to compare these naive assessments of speech acceptability with the sophisticated assessments of speech pathologists. The study group (subjects) was composed of 21 children of school age (aged 8 to 12 years) who had undergone palatoplasty at a single cleft center and 16 matched controls. The listening team (student raters) was composed of 20 children who were matched to the subjects for age, sex, and other variables. Randomized master audio-tape recordings of the children who had undergone palatoplasty were presented in blinded fashion and random order to student raters who were inexperienced in the evaluation of patients with speech dysfunction. The same sound recordings were evaluated by an experienced panel of extramural speech pathologists whose intrarater and interrater reliabilities were known; they were not direct care providers. Additionally, the master tape was presented in blinded fashion and random order to the velopharyngeal staff at the cleft center for intramural assessment. Comparison of these assessment methodologies forms the basis of this report. Naive raters were insensitive to speech differences in the control and cleft palate groups. Differences in the mean scores for the groups never approached statistical significance, and there was adequate power to discern a difference of 0.75 on a 7-point scale. Expert raters were sensitive to differences in resonance and intelligibility in the control and cleft palate groups but not to other aspects of speech. The expert raters recommended further evaluation of cleft palate patients more often than control patients. Speech pathologists discern differences that the laity does not. Consideration should be given to the utilization of untrained listeners to add real-life significance to clinical speech assessments. Peer group evaluations of speech acceptability may define the morbidity of cleft palate speech in terms that are most relevant to the patients themselves and may safeguard against the possibility of offering treatment that may be unnecessary.

Ethnic comparability of the MMPI in pain patients.

The MMPI basic validity and clinical scales' patterns of 295 White-, African- and Latino-American pain patients were compared. Mean group differences across ethnic groups on scales L, F, K, Mf, and Si were revealed in multivariate analysis of covariance for females, while differences across ethnic groups on scales F, K, Mf, Sc, Ma, and Si were revealed for males. In the univariate follow-up analyses of covariance, significant main effects were obtained for ethnicity along with education and (occasionally for males) duration of pain. Various high-point, two-point, and other profile patterns were examined and notable gender/ethnic group differences were found. The pattern of intercorrelations of the MMPI scales mean T scores with various demographic and clinical characteristics suggested some notable divergence across subgroups on certain correlates of the pain experience.

Effects of irradiation of CBA/CA mice on hematopoietic stem cells and stromal cells in long-term bone marrow cultures.

Following 200 cGy total body irradiation, 20-25% of CBA/Ca mice and their CBA/B and CBA/H sublines develop myeloid leukemia. To determine whether hematologic changes in vitro were detectable, long-term marrow cultures (LTBMCs) were established from the right and left hind limbs of 11 individual control and 11 CBA/B mice 100-114 days after 200 cGy total body irradiation. Individual cultures were studied weekly for cumulative production of nonadherent cells and colony-forming, hematopoietic progenitor cells. Control cultures produced significantly more nonadherent cells over 25 weeks in long-term marrow culture compared to those from irradiated (treated) mice. Permanent stromal cell lines were established from control and irradiated CBA/B mouse LTBMCs and clonal sublines were established. The stromal cell lines from LTBMCs of in vivo irradiated CBA/B mice had uniformly lower plating efficiencies, and only one formed a permanent clonal subline at 100-fold lower frequency compared to stromal cell lines from control mouse LTBMCs. The irradiation sensitivity of both uncloned and clonal sublines was similar by single-hit, multi-hit or by linear quadratic formula. Cocultivation of an IL-3 dependent hematopoietic progenitor cell line established from a control CBA/B, LTBMC with control of irradiated stromal cell lines derived from either a control (CC3) or the one successfully cloned in vivo irradiated (CT4) LTBMC, produced few cobblestone islands in the presence of IL-3. In contrast, formation of cobblestone islands in the presence of L cell-condition medium as a source of M-CSF was significantly greater, and these persisted for 21 days on both CC3 and CT4 stromal lines. The data provide evidence for irradiation induced changes in the bone marrow stromal cell compartment of CBA/B mice which persist and are detectable in vitro 6 months after explant of the cells to culture. These marrow stromal cell lines may provide valuable resources for analyzing the molecular biologic changes in the hematopoietic microenvironment during irradiation leukemogenesis.

Gender differences in the expression of depressive symptoms among chronic pain patients.

OBJECTIVE: To investigate the extent to which gender differences in the expression of depressive symptomatology exist among chronic pain patients. SETTING: A multidisciplinary pain center affiliated with a state medical school in the southern United States. PATIENTS: A total general sample of 245 patients with heterogeneous chronic pain complaints randomly selected from a database of approximately 1,000 pretreatment evaluation patient files. A depressed subsample of 113 patients based on scores > or = 15 on the Beck Depression Inventory (BDI). MEASURE: The 21-item BDI. RESULTS AND CONCLUSIONS: Gender differences in total BDI scores were not revealed for the total general sample or depressed subsample, but gender differences in the expression of depressive symptoms (i.e., item level responses) were found via separate discriminant function analyses on the total general sample and depressed subsample. Consistent with previous studies performed on diverse samples, females' higher endorsement of body image distortion was noted in both of our samples. Females also endorsed significantly higher levels of fatigue in our total sample. Items that were not significant in our total sample include females' higher levels of loss of appetite and crying. In the depressed subsample, items probing pessimism and failure were not statistically significantly different to males' endorsing higher levels of each. Sensitivity to these gender differences is suggested in clinical practice. The likely consequences that these differences in the experience and expression of distress have on coping activities (e.g., help-seeking responses) and the reactions of others (e.g., health-care providers) are highlighted.

Mechanism of action of cyclic AMP in altering steroid metabolism in permeabilized rat hepatocytes.

The effects of various concentrations of cyclic AMP (cAMP) on the metabolism of androst-4-ene-3,17-dione were examined in electropermeabilized rat hepatocytes. cAMP had a biphasic effect on hepatic steroid metabolism which was dependent upon both concentration and time. At low concentrations (50 microM) early (1 h) inhibitory effects predominated, whereas at higher concentrations (5 mM) later (2-3 h) stimulatory effects were seen. The use of selective protein kinase inhibitors indicated that all the effects of cAMP were mediated through activation of protein kinase A, but that the inhibitory response also involved activation of protein kinase C. The stimulatory effect was blocked by cycloheximide, indicating that protein synthesis is necessary for this response. These findings help to elucidate the mechanisms by which hormones and other compounds may give their effects on hepatic steroid metabolism and indicate a possibly novel interaction of cAMP and protein kinase C.

The role of cyclic-AMP in the regulation of steroid metabolism in isolated rat hepatocytes.

In vivo experiments have shown that hepatic steroid metabolism is under hormonal control but the intracellular mechanism of action of the hormones has been little studied. One pathway of hormone action known to be active in the liver is the alteration of cyclic-AMP levels. To investigate the role played by cyclic-AMP in the control of hepatic steroid metabolism, we raised intracellular cyclic-AMP by a number of methods and studied the resultant changes in the metabolism of androst-4-ene-3,17-dione after various periods of time. Results indicate that cyclic-AMP levels are raised to their maximal levels (2-20-fold stimulation) 2-20 min following the additions but that the effects on steroid metabolism were seen later and depended on the initial change in cyclic-AMP levels. At lower rises in cyclic-AMP (up to 5-fold stimulation), a marked inhibition of steroid metabolism is seen at 1/2-1 hr post-treatment, whereas at higher stimulations of cyclic-AMP (greater than 10-fold stimulation), a significant stimulation of steroid metabolism is observed at later time periods (after 1 hr), sometimes following a slight inhibition at 1/2 hr. This indicates that acute rises in intracellular cyclic-AMP produced by hormonal stimulation may play a role in regulating steroid metabolism in the rat liver both in an inhibitory and a stimulatory direction.