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PubMed2003

Global stationary phase and the sign problem.

We present a computational strategy for reducing the sign problem in the evaluation of high dimensional integrals with nonpositive definite weights whose logarithms are analytic. The method involves stochastic sampling with a positive semidefinite weight that is adaptively and optimally determined during the course of a simulation. The optimal criterion, which follows from a variational principle for analytic actions S(z), is a global stationary phase condition that the average gradient of the phase ImS along the sampling path vanishes. Numerical results are presented from simulations of a model adapted from statistical field theories of classical fluids.

Journal Article↗
PubMed1980

Adaptation to prismatic displacement by schizophrenics and normals.

A sample of schizophrenic inpatients and a control sample of normal volunteers, matched for age and sex were tested on two tasks before and after an exposure condition in which they pointed repeatedly to a target while viewing their hands and the target through prisms. Both groups showed significant changes in both tasks--judging the straight-ahead, and pointing to a single target without sight of the hands. The groups did not differ from each other in the amount of changes in straight-ahead judgments, but normals showed greater adaptive change in the pointing task. These results contradict earlier reports that schizophrenics fail to adapt to altered visual-proprioceptive inputs; but they also help distinguish between modes of proprioceptive utilization that do and do not differentiate schizophrenics from normals.

Adaptation, Physiological↗
PubMed2006

Does decision quality (always) increase with the size of information samples? Some vicissitudes in applying the law of large numbers.

Adaptive decision making requires that contingencies between decision options and their relative assets be assessed accurately and quickly. The present research addresses the challenging notion that contingencies may be more visible from small than from large samples of observations. An algorithmic account for such a seemingly paradoxical effect is offered within a satisficing-choice framework. Accordingly, a choice is only made when the sample contingency describing the relative evaluation of the 2 options exceeds a critical threshold. Small samples, because of the high dispersion of their sampling distribution, facilitate above-threshold contingencies. Across a broad range of parameters, the resulting small-sample advantage in terms of hits is stronger than their disadvantage in false alarms. Computer simulations and experiments support the model predictions. The relative advantage of small samples is most apparent when information loss is low, when the threshold is high relative to the ecological contingency, and when the sampling process is self-truncated.

Algorithms↗
PubMed1983

Investigations on radiosensitive and radioresistant populations of Drosophila melanogaster. XVI. Adaptation to the mutagenic effects of X-rays in several experimental populations with irradiation histories.

Selection responses of the laboratory stock Berlin wild (+60, +K) of Drosophila melanogaster to the mutagenic effects of high, accumulated exposures of X-rays were studied in several sub-populations with long irradiation histories. Interest was focussed on adaptive adjustments of mutation rates. In samples from the populations, radiosensitivities of immature oocytes were tested, by using dominant lethals (A), X-chromosome losses (B) and sex-linked recessive lethals (C) as end-points of genetic radiation damage. Populations RO II and RO V are similar to the previously studied population RO I and were exposed to 2100 R/generation, delivered to oocyte stages 6-14, mature sperm, and spermatids. RO II (first tests after 160 generations) is radioresistant relative to +60 (control). The resistance was characterized by dose-reduction factors (DRFs) of 1.72 (with respect to end-points A, B) and 1.53 (C), and these were similar to those previously obtained for RO I. The resistance of RO II was inherited semidominantly as was that of RO I, and the radiosensitivity of the hybrids RO I/RO II was similar to that of RO I and RO II with respect to end-points A and B. RO V did not become resistant within 25 generations of irradiation history (A). Populations RO III (6000 R/generation) and RO IV (7000 R/generation) have histories of irradiations given to oogonia and spermatogonia. Radiosensitivities of immature oocytes of RO III did not differ from those of +K after 55 generations, but after 105 and 135 generations of irradiation history, DRFs of 1.2 (A) and 1.44 (B) were observed. RO IV was characterized in generations 55-135 by DRFs of 1.31 (A) and 1.72 (B). Selection for relative radioresistance of immature oocytes was found (1) to be reproducible (RO II-RO IV), (2) not to require genetic pre-adaptation (RO V), and (3) to be, in part, also achieved by 'indirect' selection (RO III, RO IV). It is concluded that mutation rates in populations are selectively adjusted to evolutionary requirements.

Animals↗
PubMed2006

Monitoring changes in freshwater macroinvertebrate communities along a salinity gradient using artificial substrates.

Scientists strive to develop efficient sampling protocols, reducing both the number of samples and processing time required, which can be adapted for use in a broad range of ecosystems. We investigated the accuracy and usefulness of artificial substrates in monitoring the impact of rising salinity on freshwater macroinvertebrate communities. We sampled seven sites along a salinity gradient (from 0.2gL(-1) to 2.6gL(-1)) over a 19-km stretch of the Meurthe River, in northeastern France. All other parameters remained stable in this section of the river. Artificial substrate samples, each consisting of six liters of pebbles, were removed from the river at one-month intervals and examined. Results obtained indicated the same qualitative impairments as those found in samples collected using a Surber net. The use of artificial substrates was found to be a viable alternative method for assessing biological changes in river quality due to increasing salinity disturbance when Surber sampling cannot be performed.

Adaptation, Physiological↗
PubMed1999

Chronic pain in the elderly: occupational adaptation as a means of coping with osteoarthritis of the hip and/or knee.

OBJECTIVE: To determine whether elderly individuals with chronic pain as a result of osteoarthritis of the hip and/or knee would report adaptations to their activities, or occupational adaptations, as a coping response to pain and, if so, to describe these adaptations and their relation to chronic pain, functional difficulty, depression, social support, and life satisfaction. DESIGN: Thirty elderly individuals completed rating scales and a structured questionnaire designed to measure occupational adaptation and the importance of activity. SETTING: Participants were community-dwelling elderly individuals and were interviewed in their homes or in a research office setting. PATIENTS: Consecutive orthopedic surgeon, family physician, or Arthritis Society patients, whose names were provided with the patient's consent, to the researcher. RESULTS: Individuals reported two approaches to occupational adaptation: they changed how they performed personal activities of daily living that they rated as most important and they stopped performing a number of avocational activities that they rated as less important. Statistically significant correlations were found among occupational adaptation, pain, depression, and difficulty with functioning. These variables were inversely related to life satisfaction. CONCLUSIONS: This sample of elderly individuals with chronic pain described occupational adaptations, or adaptations to "doing," as a means of coping with their chronic pain. There appeared to be a relation among pain, functional difficulty, depression, social support, and occupational adaptation. Additional research to increase the understanding of occupational adaptation as a means of coping with chronic pain is warranted.

Activities of Daily Living↗
PubMedDate not supplied

An intramyocardial catheter for repeated in vivo sampling of interstitial fluid.

INTRODUCTION: Coronary collateral development is an important adaptive response to chronic myocardial ischemia. Characterization of mitogenic factors responsible for collateral formation has been an elusive goal because these substances are difficult to sample from the myocardial interstitium at multiple times. We report the implantation of an exchange catheter capable of in vivo sampling of myocardial interstitial fluid in chronically instrumented dogs. METHODS: The catheter consisted of multiple perforations within a 2-cm segment of Micro-Renathane tubing that was implanted into the left ventricular myocardium between the left anterior descending (LAD) and left circumflex coronary artery (LCCA) perfusion territories and secured to the epicardium with a Silastic disk. Dogs (n=5) underwent brief (2 min) LAD occlusions once per hour, 8 times/day, 7 days/week for 2 weeks to stimulate coronary collateral growth. Another group of dogs (n=6) without repetitive coronary occlusions served as controls. Myocardial interstitial fluid was collected daily, and mitogenic activity was evaluated by the proliferative responses of growth-arrested, cultured vascular smooth muscle and endothelial cells. RESULTS: All dogs tolerated catheter implantation without complication. Each catheter functioned well throughout the duration of the experiment. Myocardial interstitial fluid obtained using the exchange catheter in this model of repetitive coronary occlusion produced marked proliferation of vascular smooth muscle and endothelial cells in vitro. DISCUSSION: The exchange catheter enables chronic in vivo sampling of myocardial interstitial fluid and may facilitate identification of mitogens involved in coronary collateral development.

Animals↗
PubMed1981

Urban-suburban differences in the predictors of morale among the aged.

Research on the habitability of the city for older people and research on the predictors of well-being have led to the search for patterns of adaptation which distinguish the urban elderly adults from their non-urban counterparts. This study compares neighborhood perceptions and use and social network involvement in an urban and suburban sample of older people. Differences in patterns of adaptation characteristic of urban and suburban elderly adults were sought by comparing the ability of neighborhood and social network factors to predict morale in each sample. Results revealed differences in urban and suburban elderly adults' perceptions and use of neighborhood facilities. Urban older people reported more frequent interactions with friends, greater dissatisfaction with friendships and greater organizational participation. Informal social relationships were related to elderly urbanites' morale but had practically no bearing on suburbanites' morale. Differences in cultural heterogeneity and environmental demand seem to provide the best explanation for the findings.

Aged↗
PubMed2002

A developmental perspective on personality in emerging adulthood: childhood antecedents and concurrent adaptation.

Personality and competence were examined in a community sample of 205 children ages 8-12 who were followed up 10 years later in emerging adulthood (ages 17-23). Adult Positive Emotionality (PEM), Negative Emotionality (NEM), and Constraint (CON) were presaged by childhood personality. PEM was associated with current success in social and romantic relationships. Low CON was associated with childhood and current antisocial conduct. NEM was broadly linked to childhood and current maladaptation, consistent with the possibility that failure in major developmental tasks increases NEM. Findings highlight the pervasive linkage of NEM to maladaptation and suggest that adult personality may develop from processes embedded in childhood adaptation as well as childhood personality.

Adaptation, Psychological↗
PubMed1984

Effect of adaptation to handling on the circulating corticosterone concentration of laying hens.

Single Comb White Leghorn hens were used to determine the effects of adaptation to handling on circulating corticosterone concentrations. Blood samples were collected either by brachial venipuncture (BVP) or by brachial vein cannula (BVC). Half of the birds in each group were first adapted for 1 week to the handling procedure. Adaptation to handling resulted in reduced plasma corticosterone concentrations.

Adaptation, Physiological↗
PubMed1998

Quality assessment of protected specimen brush samples by microscopic cell count.

Protected specimen brushing (PSB), combined with quantitative culture, is now recognized as one of the reference methods for diagnosis of nosocomial pneumonia. However, no criteria exist with which to assess the quality of the PSB sample. We studied numbers of inflammatory cells and bronchial cells per microscopic field (magnification: x500, objective x50) in cytospin preparations of PSB samples. Results of cell count and quantitative culture in a first study period were compared with those in a second study period, following adaptation of the PSB technique and collection of samples from more peripheral sites. The cellular content of samples from patients and controls was investigated. We examined 86 samples from patients with suspected nosocomial pneumonia and 15 samples from uninfected controls. The number of samples with a high cellular content was considerably greater in the second study period. No positive cultures were obtained from samples containing < 10 cells per field. The numbers of cells in samples from uninfected controls were comparable to the numbers in samples from patients. Our results indicate that absence of cells probably represents inadequate sampling. Negative PSB cultures with cytospin preparations containing < 10 cells per microscopic field should therefore be considered with caution, and resampling considered.

Bacteria↗
PubMed1993

[In vitro caffeine test on skeletal muscle samples from swine].

Excitable porcine gracilis muscle samples were subjected to an in vitro caffeine test. Muscle samples were taken from pig carcasses or as biopsy from anaesthetized and halothane tested pigs. The caffeine threshold of the muscle was determined, which was the caffeine concentration of the bath that produced a contracture of the muscle sample. The in vitro caffeine test is used in human medicine to diagnose malignant hyperthermia susceptibility. In this study, the caffeine test was adapted to the particular demands of skeletal muscle samples taken from pig carcasses. The used method is described and the results from 62 pigs are reported. The in vitro caffeine test is a reliable and good reproducible method to diagnose malignant hyperthermia susceptibility in pigs. The caffeine threshold characterizes the resistance of Ca(2+)-ion-storages in the muscle fibers with a numerical value. The caffeine threshold allows a gradual evaluation of the muscle quality and represents a valuable addition to the halothane test.

Animals↗
PubMed2005

NMR-based biosensing with optimized delivery of polarized 129Xe to solutions.

Laser-enhanced (LE) 129Xe nuclear magnetic resonance (NMR) is an exceptional tool for sensing extremely small physical and chemical changes; however, the difficult mechanics of bringing polarized xenon and samples of interest together have limited applications, particularly to biological molecules. Here we present a method for accomplishing solution 129Xe biosensing based on flow (bubbling) of LE 129Xe gas through a solution in situ in the NMR probe, with pauses for data acquisition. This overcomes fundamental limitations of conventional solution-state LE 129Xe NMR, e.g., the difficulty in transferring hydrophobic xenon into aqueous environments, and the need to handle the sample to refresh LE 129Xe after an observation pulse depletes polarization. With this new method, we gained a factor of >100 in sensitivity due to improved xenon transfer to the solution and the ability to signal average by renewing the polarized xenon. Polarized xenon in biosensors was detected at very low concentrations, </=250 nanomolar, while retaining all the usual information from NMR. This approach can be used to simultaneously detect multiple sensors with different chemical shifts and is also capable of detecting signals from opaque, heterogeneous samples, which is a unique advantage over optical methods. This general approach is adaptable for sensing minute quantities of xenon in heterogeneous in vitro samples, in miniaturized devices and should be applicable to certain in-vivo environments.

Biosensing Techniques↗
PubMed1995

Comparability and validity of computerized adaptive testing with the MMPI-2.

The comparability and validity of a computerized adaptive (CA) Minnesota Multiphasic Personality Inventory-2 (MMPI-2) were assessed in a sample of 571 undergraduate college students. The CA MMPI-2 administered adaptively Scales L, E the 10 clinical scales, and the 15 content scales, utilizing the countdown method (Butcher, Keller, & Bacon, 1985). All subjects completed the MMPI-2 twice, with three experimental conditions: booklet test-retest, booklet-CA, and conventional computerized (CC)-CA. Profiles across administration modalities show a high degree of similarity, providing evidence for the comparability of the three forms. Correlations between MMPI-2 scales and other psychometric measures (Beck Depression Inventory; Symptom Checklist-Revised; State-Trait Anxiety and Anger Scales; and the Anger Expression Scale) support the validity of the CA MMPI-2. Substantial item savings may be realized with the implementation of the countdown procedure.

Journal Article↗
PubMed1995

No safe haven: a study of violence exposure in an urban community.

OBJECTIVE: To examine levels of violence exposure and reports of feeling unsafe in relation to psychological and behavioral characteristics for a general population sample of youths from an urban setting. METHOD: A comprehensive survey of high-risk behaviors, attitudes, indicators of adaptive behavior, and daily involvements was administered to a sample of 2,248 students in the 6th, 8th, and 10th grades in an urban public school system. RESULTS: More than 40% of the youths surveyed reported exposure to a shooting or stabbing in the past year, and 74% reported feeling unsafe in one or more common environmental contexts. Multiple regression analyses indicated significant relationships between violence exposure/feeling unsafe and a set of indicators of psychological and behavioral adaptation and expressed attitudes. CONCLUSIONS: These results attest to the picture of violence as a common fact of inner-city life and to the demand that is placed on urban youths to accommodate in their psychological development to chronic threat and lack of safety.

Anxiety Disorders↗
PubMed1999

A rapid and simple method for processing wood to crude cellulose for analysis of stable carbon isotopes in tree rings.

For analysis of carbon isotope discrimination in wood, cellulose or holocellulose is often preferred to whole tissue because of the variability in isotopic composition of different wood components and the relative immobility of cellulose. Most currently used methods for the preparation of wood components for stable isotope analysis (e.g., the Jayme-Wise method) produce a residue of holocellulose. The Jayme-Wise method was initially developed to extract holocellulose from small (~1 g) samples of wood, and, despite subsequent modifications, the method requires specialized glassware, considerable time and entails the risk of sample loss. For carbon isotope analysis, we adapted an acid-catalyzed solvolytic method for preparing crude cellulose by treating wood meal with acidified di-glycol methyl ether (diglyme). The one-step process requires no special glassware, is complete within 24 hours and enables over 100 samples to be processed in a day. This method gives similar delta(13)C values to the Jayme-Wise method for wood of Eucalyptus globulus Labill., Pinus radiata D. Don and Pinus pinaster Ait. The relationship between delta(13)C of wood and crude cellulose is as strong as that observed between wood and alpha-cellulose and stronger than that observed between wood and holocellulose in other species. These relationships suggest that variation in delta(13)C of wood may result from hemicellulose and that analysis of stable carbon isotopes in crude cellulose is preferable. If the consistent -0.3 bias in the value of delta(13)C of cellulose resulting from residual lignin is corrected for, then the relationship between delta(13)C of wood and crude cellulose may be used to predict delta(13)C of cellulose from a small sub-sample. The method is well suited to species with low concentrations of extractives, but further testing is needed to assess its general applicability.

Journal Article↗
PubMed2006

[Personal satisfaction of adolescent drug addicts in the family environment during treatment at a mental health institute].

This study aimed at analyzing the level of personal satisfaction of adolescents addicted to drugs in family environment during the treatment stage at a mental health institute. Authors used the Family Satisfaction Scale with Adjectives adapted, validated and applied to a sample of 34 patients selected according to established inclusion and exclusion criteria. A significant relationship between the level of satisfaction and parents' good relationship in their marriage was found. 61% of adolescents presented an average personal satisfaction level and 41.18% of them were from families whose maintenance is provided by both parents. There are no similar studies, thus, this research aims at contributing to improve rehabilitation programs based on the nursing perspective and facilitating the relationship between the family and the addicted in treatment.

Adolescent↗
PubMed1991

Adolescent clients and perceived counselor characteristics: a study of background characteristics, therapeutic progress, psychological distress, and social desirability.

Counseling dyads were investigated through the use of client ratings of their counselor (modified version of the Counselor Rating Form-Short form) and related to client background characteristics, perceived therapeutic gain, psychological distress (Revised Children's Manifest Anxiety Scale [RCMAS] and Reynolds Adolescent Depression Scale), and social desirability (Lie Scale of RCMAS). With a sample of severely emotionally disturbed adolescents (N = 45), who had received extensive counseling, only limited support was found for a relationship between counselor ratings and client background characteristics, therapeutic gain, and psychological distress. However, an important finding was the notable influence of social desirability on counselor ratings. This finding must be viewed with an understanding of the special nature of the present sample.

Adaptation, Psychological↗