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J Dunkel

Publications and source records attributed to J Dunkel.

5 recordsLinked to original sources
PubMed2003

Kramers problem in evolutionary strategies.

We calculate the escape rates of different dynamical processes for the case of a one-dimensional symmetric double-well potential. In particular, we compare the escape rates of a Smoluchowski process, i.e., a corresponding overdamped Brownian motion dynamics in a metastable potential landscape, with the escape rates obtained for a biologically motivated model known as the Fisher-Eigen process. The main difference between the two models is that the dynamics of the Smoluchowski process is determined by local quantities, whereas the Fisher-Eigen process is based on a global coupling (nonlocal interaction). If considered in the context of numerical optimization algorithms, both processes can be interpreted as archetypes of physically or biologically inspired evolutionary strategies. In this sense, the results discussed in this work are utile in order to evaluate the efficiency of such strategies with regard to the problem of surmounting various barriers. We find that a combination of both scenarios, starting with the Fisher-Eigen strategy, provides a most effective evolutionary strategy.

Journal Article↗
PubMed1992

Candidemia in a tertiary care hospital: epidemiology, risk factors, and predictors of mortality.

Demographic information, risk factors, therapy, and outcome for all patients who had candidemia at Barnes Hospital, St. Louis, between 1 September 1988 and 1 September 1989 were retrospectively reviewed. One hundred six candidemic patients were identified, representing 0.5% of all medical and surgical discharges and 0.33% of total patient discharges. These percentages represent a 20-fold increase in the incidence of candidemia at our hospital in comparison with that during 1976-1979. Candida albicans was the most frequently isolated species (63%), followed by Candida tropicalis (17%), Candida glabrata (13%), Candida parapsilosis (6.5%), and Candida krusei (0.9%). Overall mortality was 57%, and 14 (23%) of 60 deaths occurred within 48 hours of the detection of candidemia. Mortality was associated with higher APACHE II scores (25 for nonsurvivors vs. 16 for survivors; P = .0001), the presence of a rapidly fatal underlying illness (P = .0009), and sustained positivity of blood cultures (P = .02). In cases of sustained candidemia, the isolation of non-albicans Candida species also correlated with increased mortality (8 of 8 vs. 10 of 21; P = .005). Thirty candidemic patients (28%) did not receive any antifungal therapy, and 19 (63%) of these untreated patients died. Eleven untreated patients (37%) survived without sequelae. There has been a marked increase in the incidence of candidemia in our institution that is associated with a high overall mortality. Candidemia lasting less than 24 hours was associated with a lower mortality than was that of longer duration. Severity of illness and duration of candidemia should be used as stratifying factors in prospective studies to determine optimum therapy.

Adolescent↗
PubMed1983

Families in the intensive care unit: their effect on staff.

In summary, families in the ICU have had both a positive and a negative effect on staff. On the positive side there is an increased opportunity for staff to get feedback and appreciation. Goals can be realistically refocussed to help the family when a patient can no longer be helped, thus broadening the role of the staff. This also applies to the nurse advocacy role being enhanced by the increased patient data provided by the family. The opportunity to personalize the patient, to get to know him, is provided by the family's presence. And when a patient dies in the unit a family's grieving can help the staff with closure around its own grief. Families who express unrealistic demands of the ICU staff can be experienced as a stress. Staff who feel unsure of themselves or criticized by families have found the presence of families difficult. Staff who prefer to remain detached from patients also are uncomfortable with increased family presence. Feelings of rivalry with those nurses seen as "super nurses" has been a source of stress for a few in the unit. Discussions of how the staff feels about families and how certain families make the staff members feel about themselves have helped to maintain an objectivity on the part of the staff. Identifying the stress and providing support and understanding for staff have reduced the numbers of exacerbations and provided increased opportunities for staff and family to work together toward their common goal--the well-being of the patient.

Attitude↗
PubMedDate not supplied

Psychological correlates of adolescent depression.

PURPOSE: To identify psychological correlates of adolescent depression. METHODS: The subjects (N = 156) represented a convenience sample of adolescents who were attending public high schools in four Midwestern rural communities. Instruments used were: The Center for Epidemiologic Studies Depression Scale of Children, Loneliness Inventory-Short Form, Rosenberg Self-Esteem Scale, Family Strengths Inventory, and Parent-Adolescent Communication Inventory. FINDINGS: Higher levels of depression were associated with loneliness (r = .646, p < or = .001) and low self-esteem (r = .596, p < or = .001). Depression was negatively related to family strengths (r = -.293, p < or = .001). Older adolescents were more depressed than younger adolescents (r = .332, p < or = .001). A stepwise regression identified three pertinent factors associated with depression: loneliness, self-esteems, and age. CONCLUSION: Implications for nursing practice include interventions that minimize the exacerbating factors associated with depression in the adolescent population.

Adolescent↗