Electromigration of microspheres in ferroelectric smectic liquid crystals.

When an electric field is applied to microspheres which are dispersed in a ferroelectric smectic liquid crystal, particle translation along the smectic layer plane, i.e., in a direction nearly perpendicular to that of the director, can be observed. Under certain electric field conditions the translation is shown to be linear in time. We have determined the stability regime of linear particle displacement in the parameter space of amplitude and frequency for various applied wave forms. This regime enlarges for increasing electric field amplitude and frequency, with a threshold behavior observed for small parameters. The upper stability boundary is related to the reciprocal ferroelectric switching time. The microspheres translational velocity is independent of the applied electric field amplitude, but increases linearly with applied frequency. The microsphere velocity also increases with increasing temperature, which is indicative of the respective decrease in liquid crystal viscosity. Possible mechanisms of electric-field-induced particle motion are discussed.

Project: HIV prevention for incarcerated youth in Indiana.

Both Indiana and national statistics suggest that HIV-AIDS cases continue to rise in the adolescent population. Because of environmental factors, incarcerated adolescents may be at a greater risk of exposure to HIV-AIDS. Educational programs, such as the one funded for this project, may be an important step in impacting the current pandemic nature of HIV-AIDS. An educational project consisting of 4 peer-based, interactive sessions was developed for incarcerated adolescents in a north central Indiana juvenile center. The project sessions were developed from the National Network of Runaway and Youth Services (1994). Project objectives were based on the AIDS Risk Reduction Model (ARRM) and were measured by a 40-item tool developed from the ARRM. Project objectives were as follows: Detainees would (a) participate in 4 educational sessions related to high-risk sexual behavior, (b) recognize and label their own sexual behaviors that put them at risk for contracting AIDS, and (c) make a commitment to reduce high-risk sexual behaviors. During the first year of state funding, 91 educational sessions were conducted, reaching a total of 196 detainees. Following comparisons of the preproject and postproject questionnaires, detainees demonstrated an increase in their ability to appropriately recognize and label risky behaviors, but they evidenced no significant commitment to change their behaviors.

Dementia associated with periventricular and deep white matter alterations: a subtype of subcortical dementia.

This research examined the neuropsychological functioning of demented patients with periventricular and deep white matter alterations. Thirty-three outpatients with NINCDS-ADRDA probable Alzheimer's disease (AD) and 27 outpatients with probable/ possible ischaemic vascular dementia (IVD, Chui et al., 1992) associated with periventricular and deep white matter alterations matched for age, education, level of dementia, and functional disability were studied. White matter alterations were measured using a 40-point scale previously described by Junque et al. (1990). Subjects with cortical CVAs were excluded. On executive control tests, IVD subjects made more preservations on tests of mental control and response set, and produced fewer responses on phonemic controlled oral word association tests (letters: F,A,S). IVD subjects also made more preservations and graphomotor errors on clock drawings. On the California Verbal Learning Test the IVD group performed better than AD subjects on the short delay free recall test condition, the recognition discriminability index, and made fewer intrusion errors on both free and cued recall conditions. We conclude that neuropsychological assessment can differentiate AD from IVD associated with white matter alterations, and that the neuropsychological profile of demented subjects with significant periventricular and deep white matter alterations is similar to other subcortical dementing illnesses.

An assessment of Arab American knowledge, attitudes, and beliefs about AIDS.

An important component of an effective AIDS prevention program is the dissemination of relevant information concerning AIDS risk behaviors. The purpose of this study was to identify the knowledge, attitudes, and beliefs of 411 randomly selected Arab Americans. The results indicate a low level of self-assessed knowledge about AIDS, a high number of misconceptions about the transmission of HIV, and a high level of anxiety about HIV infection.

Alpha-fetoprotein levels and yolk sac size in the first trimester of pregnancy.

Transvaginal ultrasound measurement of the yolk sac and transvaginal amniocentesis were carried out on 94 women prior to first-trimester termination of pregnancy. Maternal serum and fluids from the amniotic cavity and extraembryonic coelom were analysed for alpha-fetoprotein (AFP). No correlation was found between the yolk sac size and the levels of AFP in any of these sites.

First-trimester amniotic fluid and extraembryonic coelomic fluid acetylcholinesterase electrophoresis.

Acetylcholinesterase (AChE) gel electrophoresis was performed on samples of amniotic fluid and extraembryonic coelomic fluid obtained by high resolution transvaginal ultrasound-guided amniocentesis from 38 women between 8 and 12 weeks of pregnancy. AChE was positive in 33 per cent (12/36) of the amniotic fluid samples; the percentage of positive results decreased as gestation advanced. AChE was positive in 32 per cent (9/28) of the extraembryonic coelomic fluid samples. In 81 per cent (21/26) of matched samples, the AChE results were identical in the two fluids. Amniotic fluid and extraembryonic coelomic fluid AChE electrophoresis cannot be used to diagnose neural tube defects prior to 12 weeks of gestation.

Microvillar enzyme activity in amniotic fluid, extraembryonic coelomic fluid and maternal serum in the first trimester of pregnancy.

The activities of two microvillar enzymes, gamma-glutamyl transpeptidase and total alkaline phosphatase, have been measured in samples of amniotic fluid and extraembryonic coelomic fluid obtained by high-resolution transvaginal ultrasound-guided amniocentesis from 40 women between 7 and 12 weeks of gestation. There was a highly significant difference between gamma-glutamyl transpeptidase activity in amniotic fluid (median level 31 U/l; range 2-409 U/l) and extraembryonic coelomic fluid (median level 2 U/l; range less than 2-16 U/l) (P less than 0.001; Mann-Whitney U-test). Alkaline phosphatase activity was not detected in 84% of amniotic fluid samples and 97% of extraembryonic coelomic fluid samples. No difference was found between total alkaline phosphatase activity in these fluids (P = 0.14; Mann-Whitney U-test). Enzyme activities in amniotic fluid increased with gestational age. A significant linear correlation was found between amniotic fluid gamma-glutamyl transpeptidase activity and stage of gestation (r = 0.86; P less than 0.001) and total alkaline phosphatase activity in amniotic fluid and stage of gestation (r = 0.66; P less than 0.001).

Biochemical composition of amniotic fluid and extraembryonic coelomic fluid in the first trimester of pregnancy.

OBJECTIVE: To determine the biochemical composition of amniotic fluid and extraembryonic coelomic fluid between 8 and 12 weeks gestation. DESIGN: Prospective observational study. SUBJECTS: 40 women with a normal pregnancy between 7 and 12 weeks gestation having termination of pregnancy. INTERVENTIONS: Before termination the women had a transvaginal ultrasound guided amniocentesis. Pure samples of amniotic fluid and extraembryonic coelomic fluid were obtained from each woman and standard biochemical variables were measured in each fluid sample immediately after collection. RESULTS: Levels of sodium, potassium and bicarbonate were significantly higher in amniotic fluid whilst chloride, urea, bilirubin, protein, albumin, glucose, creatinine, calcium and phosphate were present in higher concentrations in extraembryonic coelomic fluid. All differences in concentration were significant (P less than 0.05; unpaired t-test). No relation was demonstrated between electrolyte concentrations in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSIONS: Amniotic fluid and extraembryonic coelomic fluid have a widely differing biochemical composition. The biological significance of these differences remains unexplained.

Insulin-like growth factor-1 and insulin-like growth factor binding protein-1 in early human pregnancy.

Insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-1 (IGFBP-1) were measured in amniotic fluid, extraembryonic coelomic fluid and maternal serum from 23 women with apparently normal first trimester pregnancies prior to termination. The levels of IGF-1 and IGFBP-1 were significantly higher in coelomic fluid than amniotic fluid (IGF-1, P = 0.006; IGFBP-1, P = 0.0008 (paired t-test)). The levels of IGFBP-1 were lower in amniotic fluid than in maternal serum (P = 0.017), a finding in sharp contrast to the situation in the second and third trimesters of pregnancy. There was a significant relation between levels of IGF-1 and IGFBP-1 in amniotic fluid (r = 0.43; P = 0.04) and in coelomic fluid (r = 0.81; P less than 0.001) but not in maternal serum. The finding that both the absolute levels of IGFBP-1 and the ratio to IGF-1 were low in amniotic fluid implies that there is a very high level of unbound, biologically active IGF-1 in this compartment in the first trimester. Thus, the regulatory role of IGFBP-1 may change as pregnancy advances.

Early amniocentesis: alphafetoprotein levels in amniotic fluid, extraembryonic coelomic fluid and maternal serum between 8 and 13 weeks.

OBJECTIVE: The aim was to establish a normal range of alphafetoprotein (AFP) concentrations in amniotic fluid from 8 to 12 weeks gestation, and to determine any difference between AFP levels in amniotic fluid and extraembryonic coelomic fluid. DESIGN AND SUBJECTS: 150 women had a transvaginal ultrasound guided amniocentesis before termination of an apparently normal first trimester pregnancy. Separately identified samples of amniotic fluid and extraembryonic coelomic fluid were obtained and assayed by radioimmunoassay for AFP. RESULTS: In amniotic fluid, very high levels of AFP were present at 8 weeks, levels falling rapidly up to 10 weeks after which there was a slight rise. Thus over the period 8 to 10 weeks, there was a significant inverse correlation between amniotic fluid AFP and gestational age (r = 0.67; P less than 0.001). In extraembryonic coelomic fluid, by contrast there was no trend in AFP relative to gestational age. CONCLUSIONS: The rapidly changing levels of AFP from 8 to 10 weeks as well as the small volume of the amniotic cavity makes the use of amniocentesis impracticable before 11 weeks gestation. The lack of any relation between AFP levels in amniotic fluid and extraembryonic coelomic fluid emphasises the importance of identifying the site of amniocentesis in the first trimester.

Human chorionic gonadotrophin and alpha-fetoprotein levels in matched samples of amniotic fluid, extraembryonic coelomic fluid, and maternal serum in the first trimester of pregnancy.

Separately identified samples of amniotic fluid and extraembryonic coelomic fluid obtained by high resolution transvaginal ultrasound-guided amniocentesis from 32 women between 7 and 12 weeks of pregnancy were analysed for human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP). There was a highly significant difference between the hCG levels in amniotic fluid (median level 6.3 U/ml; range 1.6-310.0 U/ml) and those in extraembryonic coelomic fluid (median level 400.0 U/ml; range 135.0-2250.0 U/ml) (p less than 0.001; Mann-Whitney U-test). The levels of AFP were very similar in amniotic fluid (median 26.0 kU/ml; range 10.0-116.5 kU/ml) and extraembryonic coelomic fluid (median level 24.1 kU/ml; range 12.4-94.4 kU/ml).

PIP: Physicians used transvaginal ultrasound to guide the aspiration needle into the amniotic fluid and extraembryonic celomic fluid from 32 women at 7-12 weeks gestation in St. Bartholomew's Hospital or Homerton Hospital in London, England. They also collected blood. Their intent was to determine the levels of alpha fetoprotein (AFP) [a fetal product] and human chorionic gonadotropin (hCG) [a placental product]. All of the these women had normal pregnancies, but were in the hospital to undergo a therapeutic abortion. Levels of hCG in the amniotic fluid stood significantly lower (median 6.3 U/ml) than those in the extraembryonic celomic fluid (400 U/ml; p.001). Serum levels of hCG were in between those in the fluids (75 U/ml). AFP levels in the amniotic fluid (26 U/ml) and extraembryonic celomic fluid ((24 U/ml) were not significantly different. No definitive trend in hCG or AFP levels with gestation in the 2 fluids occurred. A possible explanation for the higher levels of hCG levels in the extraembryonic celomic fluid may be that the extraembryonic celom is next to the chorion from where hCG originates. The amnion effectively separates the extraembryonic celom from the amniotic fluid. Perhaps the extraembryonic celomic fluid works as a sump for hCG. These results stress the importance of confirming the exact site of aspiration in the 1st trimester amniocentesis. Moreover, the transvaginal ultrasound is superior to the abdominal ultrasound in distinguishing between the 2 cavities since it has the necessary degree of resolution. It also is an effortless and precise method amniocentesis. These results also suggest that physicians can make and earlier diagnosis of neural tube defects since AFP leaks into its surroundings at a very early gestation.

AIDS: who will care at home?

This study examined a program to educate providers of home health care about AIDS. A U.S. Public Health Service-funded program PROJECT Tec-HI, was designed to train family members, friends, and homemaker/home health aides to care for AIDS patients. Students had classroom and clinical learning opportunities. Pre- and posttesting of five AIDS-related items embedded in a scale of general health care knowledge suggested differential learning of AIDS content. Students with experience caring for AIDS patients completed the curriculum significantly more often. The greater the level of students' knowledge on pretest the more likely they were to complete PROJECT Tec-HI. Results suggested that even persons willing to learn about AIDS are not immune to fears that preclude their ability to learn about the disease. This study suggests that AIDS educators must help students deal with their levels of fear in order to prepare quality care givers for AIDS patients.

Aliasing in the parafovea with incoherent light.

We compared discrimination and detection in the parafovea for oblique, cathode-ray-tube-generated, square-wave gratings. There is a band of frequencies between roughly 10 and 20 cycles/deg wherein such gratings are detected only in an apparently aliased form. The existence of aliasing is consistent with the cone density and optical quality of the parafoveal visual system, but the spatial frequency at which the aliasing is observed is only about half of what is suggested by cone density. The reason for this result is unclear, but one provocative possibility is that the site of the aliasing is neural rather than receptoral.

Facilitatory interactions between flashed lines.

The detectability of pairs of flashed lines was investigated as a joint function of their separation in both space and time. In contrast to previous studies of contrast interactions as a function of either spatial or temporal separation alone, the predominant interaction is not lateral inhibition, but a delayed facilitation. A quantitative model based on probability summation between lateral-inhibitory detectors does not appear able to account for these results. Two related explanations are suggested: either a motion detection system or the nonlinear 'transient' subsystem is being tapped.