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Biomedical subjects

P Armbruster

Publications and source records attributed to P Armbruster.

18 recordsLinked to original sources
PubMed2001

Geographic variation and the evolution of reproductive allocation in the pitcher-plant mosquito, Wyeomyia smithii.

We measured the egg size of six geographic populations of the pitcher-plant mosquito, Wyeomyia smithii, from Florida (30 degrees N) to Ontario (49 degrees N). Populations from northern latitudes produced larger eggs than populations from southern latitudes. Egg size increased with increasing latitude more rapidly when larvae were reared under low rather than high density. One southern (30 degrees N) and one northern (49 degrees N) population of W. smithii that persisted through 10 generations of selection for increased persistence under conditions of chronic thermal- and nutrient-limiting stress (conditions similar to southern rather than northern habitats) produced smaller eggs more rapidly than unselected control lines. However, there were no differences in lifetime fecundity or fertility between control and selected lines. Thus, laboratory evolution in an environment representative of extreme southern latitudes caused evolutionary changes consistent with geographic patterns of egg size. These results implicate temperature as a selective factor influencing the geographic variation of egg size in W. smithii, and demonstrate a novel trade-off in reproductive allocation between egg size and egg maturation time.

Animals↗
PubMed2000

Equivalent inbreeding depression under laboratory and field conditions in a tree-hole-breeding mosquito.

Understanding the consequences of inbreeding has important implications for a wide variety of topics in population biology. However, most studies quantifying the effects of inbreeding are performed under artificial farm, greenhouse, laboratory or zoo conditions. Although several authors have argued that the deleterious effects of inbreeding (inbreeding depression) are likely to be more severe under natural field conditions than in artificial experimental environments, these arguments are usually speculative or based on indirect comparisons. We quantified the effects of inbreeding on fitness traits in a tree-hole-breeding mosquito Aedes geniculatus) under near-optimal laboratory conditions and in three natural tree holes. Our index of fitness (Ro) was lower in the field than in the laboratory and declined due to inbreeding in both However, environments, we found no significant interactions between inbreeding depression and environmental conditions. In both the field and laboratory a 10% increase in the inbreeding coefflicient (F) led to a 12-15) decline in fitness (Ro) These results suggest that inbreeding depression will not necessarily be more extreme under natural field conditions than in the laboratory.

Aedes↗
PubMed2000

Cross sections of spallation residues produced in 1A GeV 208Pb on proton reactions.

Spallation residues produced in 1 GeV per nucleon 208Pb on proton reactions have been studied using the Fragment Separator facility at GSI. Isotopic production cross sections of elements from 61Pm to 82Pb have been measured down to 0.1 mb with a high accuracy. The recoil kinetic energies of the produced fragments were also determined. The obtained cross sections agree with most of the few existing gamma-spectroscopic data. The data are compared with different intranuclear-cascade and evaporation-fission models. Drastic deviations were found for a standard code used in technical applications.

Journal Article↗
PubMed2000

Evaluation of expanded school mental health programs.

Expanded school mental health programs provide a full range of mental health services (assessment, treatment, case management, prevention) to youth in regular and special education, and typically involve close collaboration between schools and community agencies. A major challenge for these programs is documenting that provided services are of high quality and leading to enhanced outcomes for the youth and schools served by them. Dimensions of school mental health evaluations and a step-by-step process for conducting them are presented, using the example of a well established program in Baltimore. Challenges to such evaluation and strategies for overcoming challenges are also presented.

Adolescent↗
PubMed1999

Collision or collaboration? School-based health services meet managed care.

Describes interactions of for-profit managed-care organizations (MCOs) with not-for-profit school mental health programs that are affiliated with school-based health centers (SB-HCs). Discussion focuses on the developments and challenges that emerged between SBHCs and MCOs. While relations between MCOs and more traditional forms of mental health services (e.g., community mental health centers) are becoming established, such relations with SBHCs remain far from established. The example of the pathway Connecticut has taken in the continuing dialogue between SBHCs and MCOs is described in detail. Attention is given to the advocacy groups for child and adolescent mental health that were instrumental in convincing legislatures to enact safeguards to maintain SBHCs as providers of health and mental health care in the era of managed care. Challenges and recommendations are outlined to insure that the mental health needs of underserved, disadvantaged children are met through the provision of school-based mental health services.

Adolescent↗
PubMed1999

Are school based mental health services effective? Evidence from 36 inner city schools.

In an effort to bridge the gap between service need and service utilization, an urban based, university-affiliated children's psychiatric outpatient clinic implemented a program which provides mental health services in inner city schools. Since impressions of school and mental health personnel affirmed the effectiveness of such services, an evaluation of this program was conducted, despite the difficulties inherent in implementing research in "naturalistic settings." A clinic sample of children (N = 220) was compared with a sample served in the urban schools (N = 256). The findings revealed that both sets of children showed improvement as indicated by the Children's Global Assessment Scale (C-GAS) and Global Assessment of Functioning Scale (GAF). The improvement was comparable, even though the school children were seen for a slightly shorter period of time (an average of 5 versus 8 months) but had an equally frequent level of service (3 sessions per month in each setting). This finding may have important implications for the managed care environment. These results indicate that school based mental health services show improvement comparable to the clinic-based services, and have the potential for bridging the gap between need and utilization by reaching disadvantaged children who would otherwise not have access to these services.

Adolescent↗
PubMed1999

Evolutionary responses to environmental stress by the pitcher-plant mosquito, wyeomyia smithii

We performed truncation selection for increased fitness (rc) under conditions of chronic stress from the combined effects of low nutrients and high temperature, representative of extremes likely to be encountered in nature by the pitcher-plant mosquito, Wyeomyia smithii. We performed selection on geographical parental populations and their hybrids to determine whether hybridization would facilitate or constrain adaptation under our selection protocol. The stressful environment decreased fitness (rc) by 54% averaged across all populations relative to near-optimal conditions. After approximately 10 generations of selection under chronically stressful conditions, exactly one-half of the parental and one-half of the hybrid populations had gone extinct. Thus hybridization had no effect on the likelihood of population persistence. Fitness (rc) of the surviving populations did not show any response to selection. Despite initial hybrid vigour under stressful conditions, the fitness (rc) of surviving hybrid populations was either equal to, or worse than, the fitness (rc) of surviving parental populations after approximately 10 generations of selection. These results suggest that outcrossing populations to augment genetic variation and facilitate adaptation to a rapidly changing environment may not be useful over longer time scales, even in cases where hybridization does initially increase fitness. Although we detected no direct response to selection for increased fitness (rc) under lifetime chronic stress, selected populations showed a strong correlated response for survivorship through transient, acute heat and desiccation shock. In evaluating how organisms might respond to future climate change, biologists must maintain a clear distinction between lifelong performance in chronically stressful environments and short-term survivorship through transient, acute stress.

Journal Article↗
PubMed1997

Bridging the gap between service need and service utilization: a school-based mental health program.

In an effort to bridge the gap between service need and service utilization, an urban based, university affiliated children's psychiatric outpatient clinic has implemented a program which provides mental health services in inner city schools. When compared with the central clinic populations (N = 304), the school sample (N = 44) was markedly socioeconomically disadvantaged, minority, and as psychiatrically impaired as the central clinic population. School based mental health services have the potential for bridging the gap between need and utilization by reaching disadvantaged children who would otherwise not have access to these services. Implications for such services are discussed.

Adolescent↗
PubMed1994

Clinical, sociodemographic, and systems risk factors for attrition in a children's mental health clinic.

Clinical, sociodemographic, and systems risk factors for attrition at a child guidance clinic were identified. All patients who completed the intake process were followed through various clinic phases. Lower socioeconomic status and low family cohesion predicted dropout. Dropouts and continuers were equally psychiatrically impaired. The Family Environment Scale was the only standardized measure that distinguished between dropouts and continuers.

Adolescent↗
PubMed1994

Sociodemographic characteristics of dropouts from a child guidance clinic.

OBJECTIVE: This study examined the characteristics of families who dropped out and families who maintained contact with a children's psychiatric outpatient clinic through various phases of intake and treatment. METHODS: One year after intake, the authors examined the status of all patients (N = 555) who had sought treatment at an urban, university-affiliated children's psychiatric outpatient clinic over a two-year period and had completed the intake process. Factors associated with dropout were identified at four points in the clinic process: during intake, during evaluation, at completion of evaluation, and during treatment. RESULTS: Urban residence, minority status, single-parent status, and Medicaid status were related to dropout at intake and during evaluation but not at subsequent clinic phases. Nonminority, two-parent, suburban families of higher socioeconomic status were more likely to drop out at the completion of the evaluation. CONCLUSIONS: These results indicate that factors associated with attrition vary with the clinic phase. Further investigations of the clinical course of minority children and families involved with children's mental health services are necessary to understand the needs of this population and to design interventions such as increasing minority staff and providing training in multi-cultural competence.

Adolescent↗