Spatial discrimination against background with different optical systems for collection of fluorescence in laser-excited atomic fluorescence spectrometry with a graphite tube electrothermal atomizer

A single 90 degrees off-axis ellipsoidal mirror fragment was used in a dispersive detection system for electrothermal atomization laser-excited atomic fluorescence spectrometry. The performance of the new optical arrangement was compared with those of optical arrangements that employed a plane mirror in combination with biconvex or plano-convex lenses. All the optical arrangements collected fluorescence in a scheme called front surface illustration. BEAM-4, an optical ray tracing program, was used for calculations of spatial ray distributions and optical collection efficiency for the various optical configurations. Experimentally, the best collection efficiency was obtained by use of the ellipsoidal mirror, in qualitative agreement with simulations done by use of the BEAM-4 software. The best detection limit for cobalt with the new optical arrangement was 20 fg, which was a factor of 5 better than that obtained with conventional optical arrangements with otherwise the same instrumentation. The signal-to-background ratio and the fluorescence collection efficiency were also studied as a function of position of the optical components for the various optical arrangements. For both cobalt and phosphorus, the signal-to-background ratio with the new optical arrangement remained stable within 10-20% during +/- 8 mm shifts in the position of the detection system from the focal plane of the optics. Overall, the new optical arrangement offered high collection efficiency, excellent sensitivity, and facile optical alignment due to efficient spatial separation between the fluorescence signal and the background radiation. The advantages of the new optical arrangement were particularly important during measurements in the presence of high levels of blackbody radiation.     

Detection of clonal immunoglobulin gene rearrangements in the PBPC harvests of patients with acute lymphoblastic leukaemia

We have used a fluorescently based PCR technique to detect rearrangements in the immunoglobulin heavy chain (IgH) gene in the presentation BM of five patients with adult ALL and have looked for similar rearrangements in their PBPC. Using this approach we have been able to demonstrate clonal rearrangements in the PBPC of two of five patients. Remission BM samples taken 6-12 weeks prior to leucapheresis failed to show a clonal rearrangement in either patient. The significance of these results is discussed.     

How sleep and mental disorders are related to complaints of daytime sleepiness

BACKGROUND: Daytime sleepiness is widespread and has negative impacts on the public sector. OBJECTIVE: To ascertain the incidence and prevalence of daytime sleepiness and associated risk factors in the general population. METHOD: In 1994, a representative sample of the non-institutionalized British population aged 15 years or older was interviewed via telephone using an expert computer-assisted program designed to facilitate surveys of this type (Sleep-Eval, M. M. Ohayon, Montreal, Quebec). Subjects were classified into 3 groups based on the severity of their daytime sleepiness. We completed 4972 interviews (acceptance rate, 79.6%). RESULTS: Severe daytime sleepiness was reported in 5.5% (95% confidence interval, 4.9%-6.1%) of the sample, and moderate daytime sleepiness in another 15.2% (95% confidence interval, 14.2%-16.2%). Associated factors with severe daytime sleepiness included female sex, middle age, napping, insomnia symptoms, high daily caffeine consumption, breathing pauses or leg pain in sleep, depressive disorder (based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria), falling asleep while reading or watching television, and motor vehicle crashes or accidents involving use of machinery. Moderate daytime sleepiness was associated with female sex, napping, insomnia symptoms, arthritis or heart disease, and gross motor movements during sleep. CONCLUSIONS: It is likely that daytime sleepiness deleteriously affects work activities, social and/or marital life, and exhibits a negative socioeconomic impact. In addition, the risk of a motor vehicle crash appears to be higher in this specific population: twice as many subjects operating a motor vehicle or using machine tools reported having a crash or accident, respectively, in the previous year in the groups with severe daytime sleepiness or moderate daytime sleepiness than did the general population with no daytime sleepiness. The high prevalence rates of daytime sleepiness and multiplicity of related factors mandate further scrutiny by public health officials.     

Circadian and seasonal variation of the body temperature of sheep in a tropical environment

To determine whether racial differences exist in psychosocial variables among patients with non-insulin-dependent diabetes mellitus (NIDDM), the authors administered a series of questionnaires to 211 Black and White patients of the Wake Forest Family Medicine ambulatory care unit and the Reynolds Health Center, a community health center. In general, Blacks in the study population had higher levels of external locus of control, higher levels of stress, and lower levels of family functioning compared with Whites. These differences may account partially for the disparity of diabetes control and the consequences of diabetes among Blacks. Health professionals may benefit from understanding and addressing these psychosocial variables and may be more successful in implementing intervention programs in this population by tailoring programs to the psychosocial orientation of their population.     

Impact of UV radiation on activity of linear furanocoumarins andBacillus thuringiensis var.Kurstaki againstSpodoptera exigua: Implications for tritrophic interactions

Acidic fogs with a pH of 2.0 and duration of 2 hr did not reduce the efficacy ofBacillus thuringiensis var.Kurstaki (Berliner). Therefore, the impact of UV radiation was investigated on the interactions between (1) levels of the antibacterial linear furanocoumarins psoralen, bergapten, and xanthotoxin inApium graveolens (L.) occurring following a 2.0 pH acidic fog episode, (2) the noctuidSpodoptera exigua (Hübner), and (3) a sublethal dosage of the microbial pathogenB. thuringiensis var.Kurstaki. Mean time to pupation in the absence of UV radiation (survival was too low to conduct this analysis for insects exposed to UV) was significantly extended by the addition of either psoralens orB. thuringiensis. Larvae developing on diets containingB. thuringiensis plus psoralens required nearly 40% longer to pupate than controls, but their effects were additive as the interaction was not significant. Although the mean times to adult emergence were significantly different, time spent in the pupal stage did not vary significantly between treatments, indicating that increases in larval developmental time were responsible for the observed decrease in developmental rate. Mean time to mortality, a weighted average time of death, was not significantly affected by any of the treatments. In a 2 × 2 × 2 factorial analysis, all main effects (linear furanocoumarins.B. thuringiensis, UV radiation) reduced survival significantly, as did the three-way interaction. Thus, antagonistic interactions with psoralens that would reduce the effectiveness ofB. thuringiensis in the field were not observed. When pairs of main effects were nested within the two levels (presence and absence) of the third factor, several two-way interactions were found. Interestingly, the activity ofB. thuringiensis and the psoralens, individually or in combination, was enhanced by exposure to UV radiation. Implications of this research are discussed for both natural and agricultural ecosystems.Lepidoptera: Noctuidae.     

The cognitive mediation of obsessive-compulsive handwashing

The potential mediating roles of danger expectancies, responsibility, perfectionism, anticipated anxiety and self-efficacy on obsessive-compulsive handwashing were examined. Ratings were obtained from 27 obsessive-compulsive patients before and during a behavioural avoidance test involving a compound stimulus of potting soil, animal hair, food scraps and raw meat. Correlation and partial correlation analyses were conducted to examine the relationships between the cognitive predictor variables and anxiety, urge to wash, time in task and duration of post-test washing. Large and significant relationships between danger expectancies and the dependent measures were obtained, even when alternative mediators were held constant. No other variable remained significantly related to any of the dependent measures when severity of disease ratings were held constant. Results suggest that of the cognitive variables examined, danger expectancies are the most likely mediator of washing-related behaviour in obsessive-compulsive disorder.