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PubMed1994

Power spectrum analysis of bursting cells in area MT in the behaving monkey.

It is widely held that visual cortical neurons encode information primarily in their mean firing rates. Some proposals, however, emphasize the information potentially available in the temporal structure of spike trains (Optican and Richmond, 1987; Bialek et al., 1991), in particular with respect to stimulus-related synchronized oscillations in the 30-70 Hz range (Eckhorn et al., 1988; Gray et al., 1989; Kreiter and Singer, 1992) as well as via bursting cells (Cattaneo et al., 1981a; Bonds, 1992). We investigate the temporal fine structure of spike trains recorded in extrastriate area MT of the trained macaque monkey, a region that plays a major role in processing motion information. The data were recorded while the monkey performed a near-threshold direction discrimination task so that both physiological and psychophysical data could be obtained on the same set of trials (Britten et al., 1992). We identify bursting cells and quantify their properties, in particular in relation to the behavior of the animal. We compute the power spectrum and the distribution of interspike intervals (ISIs) associated with individual spike trains from 212 cells, averaging these quantities across similar trials. (1) About 33% of the cells have a relatively flat power spectrum with a dip at low temporal frequencies. We analytically derive the power spectrum of a Poisson process with refractory period and show that it matches the observed spectrum of these cells. (2) About 62% of the cells have a peak in the 20-60 Hz frequency band. In about 10% of all cells, this peak is at least twice the height of its base. The presence of such a peak strongly correlates with a tendency of the cell to respond in bursts, that is, two to four spikes within 2-8 msec. For 93% of cells, the shape of the power spectrum did not change dramatically with stimulus conditions. (3) Both the ISI distribution and the power spectrum of the vast majority of bursting cells are compatible with the notion that these cells fire Poisson-distributed bursts, with a burst-related refractory period. Thus, for our stimulus conditions, no explicitly oscillating neuronal process is required to yield a peak in the power spectrum. (4) We found no statistically significant relationship between the peak in the power spectrum and psychophysical measures of the monkeys' performance on the direction discrimination task.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1993

Proton stopping powers in some low-Z elements.

For some calculations, the proton stopping power in tissue must be known accurately. The composition of tissue was assumed to be constituted of 11 elements; the proton stopping powers were available for hydrogen, carbon, nitrogen, and oxygen. Those for the remaining 7 elements for the energy range 0.5 to 10 MeV at intervals of 0.5 MeV are evaluated and presented in this paper. Corrections such as the Barkas effect correction, Bloch's correction, and shell correction are evaluated and used in the calculation of proton stopping powers. Corrections for the Bethe formula for heavy ions were suggested by Barkas et al. (Phys. Rev. Lett. 11, 26, 1963) when they observed that the stopping powers for positive ions were larger than those for the negative ions with identical velocities. They suggested that a charge-dependent correction term be incorporated in the Bethe formula. Theoretical estimates of this correction derived by Ashley et al. (Phys. Rev. 85, 2392-2397, 1972) were used in the calculation of the Barkas effect. The Barkas effect correction depends on projectile velocity and Z. It decreases with energy. To account for the discrepancy between the classical and the quantum mechanical treatment of the Bethe formula, Bloch (Ann. Phys. 285, Chap. 18, 1933) suggested a correction to the stopping-power formula; this correction is also evaluated in this paper. Bloch's correction also decreases with energy. The shell correction needed for the binding of the electrons in the target atom is also calculated using Walske's asymptotic formula taking into account the screening effect of the atomic electrons of the K and L shells of the target atom. A computer program was written to calculate the stopping powers of protons with all these corrections for seven low-Z elements which are part of the tissue composition. These values are compared with those of other authors, and fairly good agreement is found. The lack of sufficient experimental information and uncertainty in the mean excitation energy values and shell corrections area are some of the causes for the differences in the evaluation of stopping power by the different authors.

Calcium↗

PubMed1996

[Power Doppler in breast diseases: preliminary results].

Since 1993, a new technique called power Doppler or color Doppler energy, based on Doppler signals, has been used to study the vascularization of various organs. Since power Doppler appears to permit better assessment of slow flow than color Doppler, we used this technique to study the vascularization of breast lesions. Seventy-five patients (age range: 33-81 years, mean: 53 years) were examined: 28 had simple or complex cysts, 4 cysts with internal echoes, 1 fibrocystic disease, 3 nodular fibrocystic disease, 12 fibroadenoma, 3 benign microcalcifications, 10 cancer, 3 scarring, 1 recurrent cancer, 7 axillary nodes; 3 young patients with no breast disease were also examined as a control group. All the patients were examined first with B-mode and then with color power Doppler; both during the exam and later on, in the study of similar sections, power Doppler signals were stronger and, in many cases, more numerous. Particularly, with power Doppler, in similar sections, 1-3 more signals were demonstrated in healthy women and 1-4 more signals in fibroadenomas with rich vascularization and in neoplasms, while in 2 cysts perilesional signals were demonstrated only with power Doppler. Color-Doppler semiology of breast lesions was confirmed. Thus, since the signals were stronger with power Doppler, we believe it to be a promising tool in the study of the vascularization of breast lesions which can provide useful diagnostic information as to lesion nature, the results of local treatment and the response to primary medical therapy, as well as in the study of axillary lymph nodes.

Adult↗

PubMed1997

Exposure of children to residential magnetic fields in Norway: is proximity to power lines an adequate predictor of exposure?

The aim of this work was to study the exposure to magnetic fields of children living at different distances from a power line and to evaluate how well theoretical calculations compared with actual exposure. Personal exposure instruments were carried for 24 h by 65 schoolchildren living 28-325 m from a 300 kV transmission line; the current load was 200-700 A. About half of the children attended a school far from the power line, whereas the other half attended a school located about 25 m from the line. Exposure to magnetic fields was analyzed for three categories of location: at home, at school, and at all other places. Time spent in bed was analyzed separately. The results indicated that children who lived close to a power line had a higher magnetic field exposure than other children. The power line was the most important source of exposure when the magnetic field due to the line was greater than about 0.2 microT. Exposure at school influenced the 24 h time-weighted average results considerably in those cases where the distance between home and power line was very different from the distance between school and power line. The calculated magnetic field, based on line configuration, current load, and distance between home and power line, corresponded reasonably well with the measured field. However, the correlation depends on whether home only or 24 h exposure is used in the analysis and on which school the children attended. The calculated magnetic field seems to be a reasonably good predictor of actual exposure and could be used in epidemiological studies, at least in Norway, where the electrical system normally results in less ground current than in most other countries.

Child↗

PubMed1997

The influence of muscle group location and race on the relationship between muscle strength and power.

OBJECTIVE: This study investigated the influence of muscle group location and racial background on the relationship between measures of muscle strength and power. It was hypothesized that both African American (AA) and Caucasian American (CA) males would exhibit similar strength-power relationships, but these relationships would be dependent upon muscle group location. EXPERIMENTAL DESIGN: A cross-sectional, comparative design was used. SETTING: The Human Performance Laboratory at the U. of Oklahoma. SUBJECTS: Normal, healthy college-aged AA (n = 14) and CA (n = 15) males volunteered for this study. MEASURES: Upper and lower body strength (IRM) was assessed using a Smithpress bench press and Polaris leg press, and upper and lower body power was measured with a piezoresistive accelerometer. RESULTS: When comparing power between upper and lower body muscle groups, both AA and CA groups exhibited similar relationships (r = 0.68 and r = 0.61, respectively), however, the relationship between upper and lower body strength was relatively stronger for the AA group (r = 0.65 vs r = 0.42). When evaluating the strength-power relationship within a given muscle group, i.e., upper or lower body, there were no racial differences, but the relationship between strength and power did differ with respect to muscle group location. CONCLUSIONS: There were stronger relationships between measures of muscular strength and power for the lower limbs when compared to the upper body indicating the importance of muscle group location rather than racial ethnicity as a confounding factor that can affect neuromuscular force production. This information is important when attempting to characterize neuromuscular function relative to specific skills or motor sport performance, thus emphasizing the principle of specificity.

Acceleration↗

PubMedDate not supplied

Child abuse and the balance of power in parental relationships: an evolved domain-independent mental mechanism that accounts for behavioral variation.

Previous studies use zero-order analyses to show a link between child abuse and exposure to "stepfathers." These studies rest on a proposed evolved, domain-specific cognitive mechanism that induces adult males to abuse or kill offspring not their own and, so, contribute directly to reproductive success. However, child abuse may reflect an evolved neurological mechanism that creates behavioral plasticity and adaptability by assigning emotional weights (which in consciousness appear rationalized as costs and benefits) to choice alternatives in all behavioral domains. This mechanism should act as a selective mechanism to create enhanced ability to avoid predation (social exploitation) and to obtain access to resources, given the properties of specific ecosystems, and should control behavioral responses to variation in the balance of power in social relationships. Power equalities should elicit good treatment for both parties; power inequalities, by contrast, should elicit exploitative and coercive behavior on the part of those who hold the balance of power. This paper reports a test of both hypotheses simultaneously, controlling for a standard social science risk factor (growing up in poverty). Once we control for the balance of power in parental relationships, exposure to a stepfather and growing up in poverty show no effect on the intensity of child abuse. Powerful women negotiated affectionate behavior from their partners for both themselves and their children; powerless women's negotiations with partners usually left both themselves and their children open to violence.

Adult↗

PubMed1999

Implicit power motivation moderates men's testosterone responses to imagined and real dominance success.

This study tested the hypothesis that implicit power motivation moderates individuals' testosterone responses to the anticipated success in and actual outcome of a dominance contest. Salivary testosterone levels were assessed in 42 male students at the beginning of the study, after they had imagined a success in an ensuing power contest, and immediately after the contest had taken place. Contest outcome (winning or losing against a competitor on a speed-based task) was varied experimentally. Participants' power motive was assessed with a picture-story exercise, in which an assertive, personalized (p Power) component was distinguished from an altruistic, socialized (s Power) component. In contrast to all other participants, individuals high only in p Power (a) had elevated testosterone after imagining a success in a subsequent dominance contest and (b) continued to have high testosterone levels after actually winning, but not after losing, the contest.

Adult↗

PubMed2006

The influence of power on HIV risk among pregnant women in rural Haiti.

Given that condom use is not directly under a woman's control, the sexual division of power may play an important role in sexual behavior among pregnant women. We assessed the influence of factors related to the theory of gender and power (e.g., relationship power, abuse history, and sexual communication) on sexual behavior (e.g., two or more partners in the year prior to pregnancy, condom use, condom-use intentions, and STI diagnosis) among 196 pregnant women recruited from five community dispensaries in rural Haiti. Results showed that gender and power factors significantly related to sexual behavior. Gender and power factors were most significant for condom use and intention to use condoms, accounting for 18 and 25% of the variance above and beyond HIV knowledge and demographic covariates, respectively. These results suggest the need to create prevention interventions that restore power imbalances, provide support for women suffering abuse, and strengthen communication skills.

Adult↗

PubMed1979

Tissue damage from electrosurgical power output variations in hamster tongues.

An investigation was designed to determine the differences in the amount of tissue damage produced by variations in the amount of cutting power delivered to the hamster tongue with electrosurgery. By dividing the power of an electrosurgical instrument into 5 W intervals, from the lowest setting which would produce a cut up to the 50 W setting, histometric comparisons were made in the hamster tongue. Histologic analysis showed the following: 1. The 30 W power interval produced less tissue damage than any other power interval. 2. The 25 and 35 W intervals produced significantly greater damage than the intervals from 40 thorugh 50 W. 3. Histologically the experimental defect showed an area of coagulation necrosis approximately 50 mu wide along the margin of the incision. Tissue damage decreased laterally and inferiorly from the surface of the defect except at the 30 W setting, where the damage in the epithelium and the damage in the connective tissue were essentially equal. 4. There is some validity to the sparking-dragging test for setting the power interval of an electrosurgical instrument. 5. Higher power values which produce excessive sparking should be avoided by the clinician during electrosurgery due to the imprecise nature of the clinical incision.

Animals↗

PubMed2004

Methods and practices used in incident analysis in the Finnish nuclear power industry.

According to the Finnish Nuclear Energy Act it is licensee's responsibility to ensure safe use of nuclear energy. Radiation and Nuclear Safety Authority (STUK) is the regulatory body responsible for the state supervision of the safe use of nuclear power in Finland. One essential prerequisite for the safe and reliable operation of nuclear power plants is that lessons are learned from the operational experience. It is utility's prime responsibility to assess the operational events and implement appropriate corrective actions. STUK controls licensees' operational experience feedback arrangements and implementation as part of its inspection activities. In addition to this in Finland, the regulatory body performs its own assessment of the operational experience. Review and investigation of operational events is a part of the regulatory oversight of operational safety. Review of operational events is done by STUK basically at three different levels. First step is to perform a general review of all operational events, transients and reactor scram reports, which the licensees submit for information to STUK. The second level activities are related to the clarification of events at site and entering of events' specific data into the event register database of STUK. This is done for events which meet the set criteria for the operator to submit a special report to STUK for approval. Safety significance of operational events is determined using probabilistic safety assessment (PSA) techniques. Risk significance of events and the number of safety significant events are followed by STUK indicators. The final step in operational event assessment performed by STUK is to assign STUK's own investigation team for events deemed to have special importance, especially when the licensee's organisation has not operated as planned. STUK launches its own detail investigation once a year on average. An analysis and evaluation of event investigation methods applied at STUK, and at the two Finnish nuclear power plant operators Teollisuuden Voima Oy (TVO) and Fortum Power and Heat Oy (Fortum) was carried out by the Technical Research Centre (VTT) on request of STUK at the end of 1990s. The study aimed at providing a broad overview and suggestions for improvement of the whole organisational framework to support event investigation practices at the regulatory body and at the utilities. The main objective of the research was to evaluate the adequacy and reliability of event investigation analysis methods and practices in the Finnish nuclear power industry and based on the results to further develop them. The results and suggestions of the research are reviewed in the paper and the corrective actions implemented in event investigation and operating experience procedures both at STUK and at utilities are discussed as well. STUK has developed its own procedure for the risk-informed analysis of nuclear power plant events. The PSA based event analysis method is used to assess the safety significance and importance measures associated with the unavailability of components and systems subject to Technical Specifications. The insights from recently performed PSA based analyses are also briefly discussed in the paper.

Databases, Factual↗

PubMed2001

Microbial ecology of soils surrounding nuclear and thermal power plants in Taiwan.

This paper reports a study of the effect of three nuclear and one thermal power plants on the microbial ecology of soils. Populations of bacteria, actinomycetes, fungi, cellulolytic microbes, phosphate-solubilizing microbes and nitrogen-fixing microbes in the soil in the vicinity of each plant were studied. Soils were acidic at three sites, and moisture contents of the power plant soils were lower than those of the surrounding areas. Microbial populations of the topsoils (0-20 cm deep) were higher than the subsoils (21-40 cm deep), and only 10-15% of them showed significant difference (P < .05). Thirty-three percent of the samples from the surrounding areas had higher microbial population than those from the power plant areas, but 19% was the reverse. Populations of cellulolytic, phosphate-solubilizing and nitrogen-fixing microbes varied with sampling locations, season and environmental conditions. Ratios of cellulolytic, phosphate-solubilizing and nitrogen-fixing microbes to total viable counts in some samples of the surrounding areas were significantly higher than in the power plant areas. Although the microbial populations of power plant soil and its surrounding area were somewhat different, it cannot be attributed as an effect of power plant operation, as the differences were not consistent.

Environmental Monitoring↗

PubMed1997

The lived experience of power and powerlessness in psychiatric nursing: a Heideggerian hermeneutical analysis.

The purpose of this study was to discover some of the meanings inherent in psychiatric nursing practice. The specific question was, "What is the meaning of power and powerlessness as it occurs in the lived experience of practicing psychiatric nurses." The therapeutic nurse-patient relationship is a primary concern for psychiatric nursing. Therefore, issues of power and powerlessness become salient as they affect clients in the mental health system and the clinicians who work with them. If power and powerlessness are important aspects in a conceptualization of mental illness and its treatment, then they will affect clinicians and the relationships that they have with their clients. This study focused on the lived experience of 10 psychiatric registered nurses. Semistructured interviews with these nurses were audiotaped and transcribed into text. They were then analyzed hermeneutically using the philosophical grounding of Heideggerian phenomenology and the hermeneutical methods that are based on that philosophy. One constitutive pattern revealed was "The Power of Knowing." Three relational themes were "Power as Connectedness in Relationships," "Being Tested by Fire," and "Power as Having a Voice." The results of this study enable nurses to understand their practice better and lead to strategies for empowerment of both nurses and the people that they care for. In addition, the use of a hermeneutical data analysis approach has further shown the relevance of this method for knowledge generation in psychiatric nursing.

Attitude of Health Personnel↗

PubMed2003

Impact of emission from oil shale fueled power plants on the growth and foliar elemental concentrations of Scots pine in Estonia.

To study the impact of air pollution on the growth and elemental composition of conifers, 5 sample plots were established at different distances and directions from the Estonian Power Plant (Northeast Estonia) in 1999-2000. The selected stands were 75-80(85)-yr-old parts (0.05 ha) of (Oxalis)-Myrtillus site type forest of 0.7-0.8 density. The soils of all sample plots were Gleyic Podzols (Lkg) on sands. The several times higher Ca concentration in the humus horizon of the sample plot NE from the Estonian PP is caused by the prevailing westerly and southerly winds which carry more pollutants NE from the power plant than to SSW. To ascertain the effect of power plants on the growth of Scots pine (Pinus sylvestris L.), the length growth of the needles and shoots formed in 1997-2000, dry weight of 100 needles, and density of needles on the shoots were measured. As compared to the control, the strongest inhibition of growth was revealed in the sample plots situated 22 km north-east and 17 km south-west from the Estonian Power Plant. As compared to control, the needles of trees growing on sample plots closer to the power plant showed higher contents of Ca, S and Zn. The content of Mg in needles increased with distance from the pollution source. Current year needles had higher contents of Cu and Zn than older needles. Today the amounts of fly ash emitted from Narva power plants are fallen. Long-term fly ash emission has caused changes in the measurements of morphological parameters and chemical composition of needles.

Air Pollutants↗

PubMed2004

The coping power program for preadolescent aggressive boys and their parents: outcome effects at the 1-year follow-up.

This study evaluates the effects of the Coping Power Program with at-risk preadolescent boys at the time of transition from elementary school to middle school. Aggressive boys were randomly assigned to receive only the Coping Power child component, the full Coping Power Program with parent and child components, or a control condition. Results indicated that the Coping Power intervention produced lower rates of covert delinquent behavior and of parent-rated substance use at the 1-year follow-up than did the control cell, and these intervention effects were most apparent for the full Coping Power Program with parent and child components. Boys also displayed teacher-rated behavioral improvements in school during the follow-up year, and these effects appeared to be primarily influenced by the Coping Power child component.

Adaptation, Psychological↗

PubMed2006

You focus on the forest when you're in charge of the trees: power priming and abstract information processing.

Elevated power increases the psychological distance one feels from others, and this distance, according to construal level theory, should lead to more abstract information processing. Thus, high power should be associated with more abstract thinking-focusing on primary aspects of stimuli and detecting patterns and structure to extract the gist, as well as categorizing stimuli at a higher level-relative to low power. In 6 experiments involving both conceptual and perceptual tasks, priming high power led to more abstract processing than did priming low power, even when this led to worse performance. Experiment 7 revealed that in line with past neuropsychological research on abstract thinking, priming high power also led to greater relative right-hemispheric activation.

Adult↗

PubMed2003

Power, approach, and inhibition.

This article examines how power influences behavior. Elevated power is associated with increased rewards and freedom and thereby activates approach-related tendencies. Reduced power is associated with increased threat, punishment, and social constraint and thereby activates inhibition-related tendencies. The authors derive predictions from recent theorizing about approach and inhibition and review relevant evidence. Specifically, power is associated with (a) positive affect, (b) attention to rewards, (c) automatic information processing, and (d) disinhibited behavior. In contrast, reduced power is associated with (a) negative affect; (b) attention to threat, punishment, others' interests, and those features of the self that are relevant to others' goals; (c) controlled information processing; and (d) inhibited social behavior. The potential moderators and consequences of these power-related behavioral patterns are discussed.

Cognition↗

PubMed1995

Nursing: empowerment and the problem of power.

The concept of empowerment is one which is often invoked in discussions over the nature of nursing practice in a range of health and welfare services. A short excursion through the Cumulative Index to Nursing and Allied Health Literature reveals that over the last 10 years 378 papers are identified which list empowerment as one of the topics discussed. In 1993, the number is 55. These papers cover a diverse range of health related issues: health promotion and HIV; breast feeding; mental health; management and leadership; change, training and education; feminism and women's issues; sexual abuse and violence; advocacy and working with immigrants; professionalism; and nursing theory. However, few of these papers discuss the relationship between empowerment and the notion of power itself. This gives rise to particular problems for nursing practice, for without a clear conceptualization of what is meant by power it is difficult to convincingly argue that one form of practice is more or less empowering than another. Alternatively, this dilemma may be stated in the following question: how do we work to empower others when we have no clear notion of what power is? This paper demonstrates that the concept of power demands a very specific consideration. In order to illustrate this it briefly identifies problems within two models of power which are drawn upon in nursing. It also demonstrates the way in which the work of Michel Foucault can be drawn upon to inform nursing in the analysis of the relationship between power and health.

Humans↗

PubMed2003

Power imbalance between nurses and patients: a potential inhibitor of partnership in care.

The Patient's Charter identifies the need for nurses to respect patients' rights to influence their care, and contemporary nursing practice advocates that nurses work in partnership with patients. Hence nurses are encouraged to share their power and facilitate empowerment in their patients by giving them information and support. However, the literature indicates that nurses are not very successful in making patients feel empowered to make informed decisions. This study, conducted in 1998, provides some answers as to why this may be the case. The aim of the study was to explore and describe nurses' and patients' views regarding partnership in care in hospital. Using the grounded theory approach, participants were drawn from four hospitals in Western Australia. A purposive sample of 33 nurses and 32 patients were interviewed in-depth. Participant observation was also conducted and field notes were written. The interviews were transcribed verbatim and analysed using the constant comparative method. The findings showed that nurses viewed involving patients in care as requiring them to give patients information and to share their decision-making powers with them. With the exception of a few, the majority of nurses were unwilling to share their decision-making powers. This created a situation of power imbalance with subsequent little patient input. Factors identified included nurses' beliefs that they "know best", the view that patients lacked medical knowledge and the perceived need for nurses to hold onto their power and maintain control. If nurses and patients are to work as partners, it is important that nurses make every effort to equalize the power imbalance. One way to do this is for nurses to share and give information to patients readily and to be open in their communication with them.

Attitude of Health Personnel↗