Influence of flow rate on transport of bacteriophage in shale saprolite.

The objective of this study was to investigate the influence of flow rate on transport and retention of bacteriophage tracers in a fractured shale saprolite, which is a highly weathered, fine-grained subsoil that retains much of the fabric of the parent bedrock. Synthetic ground water containing PRD-1, MS-2, and bromide was passed through a saturated column of undisturbed shale saprolite at rates ranging from 0.0075 to 0.96 m d '. First arrival of the bacteriophage tracers in effluent samples in each of the experiments occurred within 0.01 to 0.04 pore volumes (PV) of the start of injection, indicating that bacteriophage were advectively transported mainly through fractures or macropores. Bacteriophage transport velocities, based on first arrival in the effluent, were very similar to fracture flow velocities calculated using the cubic law for flow in a fractured material. For MS-2, maximum concentration and mass of tracer recovered both increased steadily as flow rate increased. For PRD-1, these values initially increased, but were nearly constant at flow rates above 0.039 m d(-1), indicating that approximately 50% of the observed losses were independent of flow rate. Evaluation of the data indicates that physical straining and electrostatic or hydrophobic attachment to fracture or macropore walls were the dominant retention processes. Inactivation and gravitational settling playing secondary roles, except at the slowest flow rates. The study suggests that microbial contamination from sources such as septic fields and sewage ponds may pose a threat to the quality of ground water and surface water in areas with saprolitic subsoils.

Increased vagal tone during winter in subsyndromal seasonal affective disorder.

BACKGROUND: Seasonal affective disorder (SAD) is characterized by recurrent winter depression with summer remissions and/or hypomania. Further symptoms include hypersomnia, increased appetite, weight gain, fatigue, and social withdrawal, which may indicate autonomic changes during winter. METHODS: Measurements of respiratory sinus arrhythmia, heart rate (HR), and skin conductance level (SCL) were taken from 32 participants in subsyndromal SAD and control groups (eight male and eight female subjects in each group) in autumn and winter to determine any change in autonomic function. Measures were taken at baseline and during two stressor tasks. Single determinations of blood pressure, sublingual temperature, depression, aerobic fitness, and body mass index were also measured at each session. Replication in a second data collection period over subsequent winter and spring periods was conducted with an additional 32 participants to extend the findings and to counterbalance order effects in testing. Data were combined to produce "winter" and "nonwinter" test periods and statistically corrected for testing order. RESULTS: Respiratory sinus arrhythmia differences indicated that SAD subjects have increased vagal tone in winter. Both groups show a decrease for HR and increases for SCL and diastolic blood pressure in winter. CONCLUSIONS: Seasonal affective disorder may show similarities with hibernation, and the results may indicate mechanisms different from those of nonseasonal depression.

The psychophysiology of self-mutilation.

Self-mutilators' psychophysiological and subjective responses during an imaged self-mutilative act were examined. Differences in arousal to 3 imaged control events (neutral, accidental injury, and aggression) were examined between 3 self-mutilation groups (prisoner, prisoner control, and nonprison control). Imagery scripts were presented in 4 stages; scene setting, approach, incident, and consequence. Results indicated a decrease in psychophysiological and subjective response during self-mutilation imagery. No such decrease was evident for nonmutilators who were administered standard self-mutilation imagery. A lag between psychophysiological and psychological response to the self-mutilative act was evident. Responses elicited during self-mutilation imagery were different from those of control imagery. Results indicated that self-mutilative behavior is maintained by its reinforcing tension-reducing qualities.

Assessing nurses' knowledge of bandages and bandaging.

The purpose of this research was to assess registered nurse understanding of bandaging principles and the extent of crèpe bandage use. Measurements were made by the use of a self-administered questionnaire designed for the purpose. Results indicated that the principles of bandaging are not well understood and that there is a high reliance placed on the use of crepe bandages. This suggests that the appropriate use of bandages, particularly for compression purposes, is below an acceptable level, which has implications both for nurse education and the availability of products.

Use of a diary technique to investigate psychosomatic relations in atopic dermatitis.

Previous research on the relationship between stress and atopic dermatitis has employed retrospective approaches such as interviews and measurement of life events and daily hassles. These studies have yielded inconsistent results. In the current study, 50 atopic dermatitis sufferers completed a diary for a fortnight, recording their daily emotional states and skin condition. The results of meta-analyses indicated that both interpersonal stress and depression were significantly related to changes in skin condition. Meta-analyses of lag sequential analyses indicated that interpersonal stress on Day X predicted skin condition on Day X + 1 and that this relationship was reciprocal. Depression was predicted by the skin condition of the previous day but this relationship was not reciprocal. These results were integrated and their implications for psychosomatic relationships between stress, depression, and atopic dermatitis were discussed.

The neuropsychiatry of post-traumatic stress disorder.

The publication of DSM-III introduced the diagnosis Post-Traumatic Stress Disorder (PTSD), thus providing, for the first time, a framework for studying the consequences of extremely stressful events. Previously, traumatic neuroses had attracted a wide variety of labels - as wide as the experiences that produced them. Competing explanations in psychological and biological terms have characterised the approach to these disorders, and social and legal issues have added to the confusion. In recent years, psychosocial issues have tended to dominate the literature in relation to PTSD. While acknowledging the importance of such phenomenological and psychosocial approaches, this paper seeks to redress the balance by focusing on a biological perspective.

On the stability of the Travelling Salesman Problem algorithm of Hopfield and Tank.

The application of the method of Hopfield and Tank to the Travelling Salesman Problem (1985) has been re-examined in an effort to find a procedure for scaling to system sizes of real interest. As this failed, methods were tried to improve the algorithm, recognizing the importance of a "silicon implementation". No satisfactory refinement was found, and the reasons for algorithm failure have been identified.

Ventilation during sleep onset.

There is now considerable evidence which indicates that respiratory activity is different during sleep compared with wakefulness. However, there has been little work on respiratory changes during the transitional period from wakefulness to sleep. The present study was concerned with the quantitative and temporal properties of ventilation during sleep onset. Sleep onsets were studied in five young male adults in a series of single-subject designs in which sleep onsets were replications. The results indicated that during sleep onset the loss of alpha-activity in the electroencephalogram was associated with a substantial, rapid, and highly predictable reduction in ventilation. The change in ventilation was typically due to a reduction in tidal volume and was, in part, secondary to a reduction in metabolic rate. We speculate that the nonmetabolic component may reflect the loss of waking neural drive to respiration, though the present study did not eliminate a variety of other interpretations.