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Results for “interaction frequencies”

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PubMed1998

Broadband ultrasound attenuation in the os calcis and its dependence on the receiver aperture size.

The broadband ultrasonic attenuation (BUA) was measured in 10 os calces on the same site with two transducer separations and five different receiving apertures built from perspex. The results displayed relative differences greater than 40%. However, a clear trend (increasing or decreasing BUA) with smaller aperture size or transducer separation was not observed and hence the differences do not seem to be predictable. The cause for this may be the influence of four factors--averaging, phase cancellation, diffraction and scattering--which are interactive and frequency dependent. This means that values measured with different equipment and experimental set-up are not directly comparable and hence the introduction of measurement standards seems to be necessary.

Calcaneus↗

PubMed2003

Solvent effects on infrared spectra of 2-acetylthiophene in organic solvents.

Infrared spectroscopy studies of 2-acetylthiophene (ACTH) in 18 different organic solvents, both polar and non-polar, were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration upsilon(C=O) of ACTH were correlated with the properties such as the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with the LSER than the AN. A six-membered ring-like hydrogen bonding structure was presented and the solvent effects of ACTH in alcohol solvents were investigated in detail.

Hydrogen Bonding↗

PubMedDate not supplied

Growth enhancement of anchorage-dependent and anchorage-independent cells by coimmobilization of insulin with poly(allylamine) or gelatin.

An anchorage-dependent cell, mouse fibroblast STO cell and an anchorage-independent cell, K562 cell, were cultured on a polymer membrane coimmobilized with insulin and adhesion factors, poly(allylamine), and gelatin. The former is cationic and electrostatically (non-biospecifically) enhances cell adhesion, and the latter is a hydrolyzate of collagen and biospecifically enhances cell adhesion. They were immobilized onto a surface-hydrolyzed poly(methyl methacrylate) membrane by water-soluble carbodiimide. The adhesion of both STO and K562 cells was accelerated by the immobilization of poly(allylamine) or gelatin. The insulin immobilization did not affect adhesion of either cell. Although the growth of STO cells was enhanced on the insulin-immobilized membrane, the growth of K562 cells was not. However, the coimmobilizaiton of insulin and a cell-adhesion factor accelerated growth of both cells. It was considered that an increased frequency of interaction between the immobilized insulin and the receptor led to the cell growth acceleration.

Animals↗

PubMed2005

Lateral intermolecular forces in the physisorbed state: surface field polarization of benzene and n-hexane at the water/ and mercury/vapor interfaces.

The available experimental data on the dependence of the surface tensions of water and mercury on the adsorption of benzene and hexane from the vapor phase are critically analyzed and interpreted to obtain the two-dimensional second virial coefficients [B(2)(T)] for these adsorbed nonpolar molecules. Calculations based on the unperturbed Lennard-Jones (L-J) 12-6 formalism for benzene and the related 12-5 Salem formalism for long chains in two dimensions for hexane require that B(2)(T) should be negative for both adsorbates. On water, the experimental data indicate that B(2)(T) for both molecules is less negative than expected from the unperturbed L-J and Salem estimates, and on mercury the B(2)(T) values from experiment are positive. These findings are analyzed first in terms of a possible reduction in the attractive component of the potential of mean force between physisorbed molecules arising from their frequency-dependent interaction with their electrostatic images in the bulk phases, as described by McLachlan. It is concluded that the McLachlan corrections are small for these molecules and surfaces. A second analysis considers the effect of an extra repulsion between the adsorbed molecules arising from the induction of dipoles normal to the interface by the surface electric field. Surface field polarization (SFP) accounts reasonably well for the experimental results, leading to estimates of the surface fields at the mercury and water surfaces which are consistent with estimates from contact potentials for mercury and computation from modeling the water surface. SFP may have a wide impact in determining the form of physisorption isotherms.

Journal Article↗

PubMed1980

Reducing the stress of high-density living: an architectural intervention.

The present study assesses the effects of an architectural intervention on residential crowding stress and poststressor effects. Residents of long-corridor, short-corridor, and long-corridor-intervention dormitory floors were surveyed and social behavior and space use patterns were systematically observed over a 3-month period. As predicted, although students living in the three environments were initially comparable, residents of the long-corridor floor (40 residents sharing space) reported more crowding and residential social problems over time, whereas short-corridor residents (20 residents sharing space) and modified long-corridor residents (20 residents sharing space) reported fewer of these problems. The results are interpreted in terms of a model of crowding in which architectural features of interior spaces are associated with space use patterns that facilitate or inhibit informal group development and regulation of the frequency of interaction and the amount of privacy. These conditions, in turn, are related to stress and stresslike symptoms.

Architecture↗

PubMed1990

Differences in social support among retirees and workers: findings from the Normative Aging Study.

Cross-sectional differences between retirees and workers in the importance of coworkers as a source of support, as well as in general quantitative support (social networks and frequency of interaction) and qualitative support (confidants and the perceived reliability of support) were examined. The sample consisted of 1,513 older men (mean age = 61), participants in the Normative Aging Study. Half (56%) were working, and the rest were retired. Slightly fewer retirees than workers reported coworker friends, especially among those who were long-term retirees or who did not work at all in retirement. Whereas similar findings were seen with quantitative support, workers and retirees reported nearly identical levels of qualitative support. However, retirees almost never discussed personal problems with former coworkers. The relevance of these findings for the convoy construct is discussed.

Adult↗

PubMed2006

The Personal Acquaintance Measure: a tool for appraising one's acquaintance with any person.

The authors developed and evaluated the psychometric properties of the 18-item Personal Acquaintance Measure (PAM) and investigated how the PAM relates to self- other agreement in personality ratings. Results support that 6 factors represent the PAM (Duration, Frequency of Interaction, Knowledge of Goals, Physical Intimacy, Self-Disclosure, Social Network Familiarity), which showed evidence of internal consistency, test-retest reliability over 3 weeks, sensitivity to known group differences, discriminant validity from socially desirable responding, and convergent validity with other relationship inventories. Results also show that the PAM positively predicted self-other agreement. The authors discuss the implications of these findings for the PAM and research in person perception, although this measure may also be used in other research areas.

Adult↗

PubMed1980

Behavioral, corticosterone, and prolactin responses to novel environment in rats with fornix transections.

These experiments examined the behavioral, corticosterone, and prolactin responses to a novel environmental in male rats with total fornix transections. During the initial exposure to the novel environment, rats with fornix transections exhibited increased latency to initiate activity and increased activity levels. There were no changes in frequency of rearing, frequency of interactions with objects in the environment, or defecation. Fornix transection was found to have no effect on resting levels of either corticosterone or prolactin but to alter significantly the stress-response profiles of each of these hormones. The corticosterone responses to the novel environment in rats with fornix lesions were of greater magnitude with no change in latency to respond or in recovery of resting levels, whereas the prolactin responses were of shorter latency with no change in magnitude or recovery or resting levels. Habituating to the novel environment by repeated exposure was found to decrease the corticosterone responses of rats with fornix lesions but not the responses of controls. The results are discussed in terms of differences between rats with fornix lesions and control rats in level of arousal and effect of experience in the environment.

Animals↗

PubMed1991

Relationship of perceived maternal acceptance-rejection in childhood and social support networks of pregnant adolescents.

In a sample of 53 at-risk pregnant adolescents, the relationship between their perceptions of maternal acceptance-rejection in childhood and the nature of their social supports was examined. Perception of acceptance-rejection was significantly correlated with both frequency of interaction with social network members and expectations of their future support. Implications for public health strategies are discussed.

Adaptation, Psychological↗

PubMed1984

Stress and coping strategies of nurse managers in the NICU.

Nursing managers in neonatal intensive care units must cope with numerous stresses that arise in the context of managing a complex medical unit. Ten nurse managers were interviewed using a structured interview to determine the frequency of interaction and the sources of stress that occur in working with physicians, hospital administration, nursing administration, and staff nurses. Physicians are a major source of stress but the issues vary depending on the role held by the nurse manager. The unwillingness of the staff nurse to appreciate the time involved in implementing any change is another major source of stress. Numerous coping strategies are being implemented to address identified sources of stresses. The intent of these strategies is to reduce stress by increasing the flow of task-relevant communication to all parties.

Adaptation, Psychological↗

PubMed1996

Drift mechanism caused by a nonlinear wave and the Cassini Division and Uranian rings formation.

The mechanism leading to the observed coexistence of gaps and narrow ringlets in the planetary rings is found. It is based upon the quasi-stationary radial drift of the matter under action of two forces in the disk plane: the Coriolis force and the Reynolds stresses. To an accuracy of the factor of 2 the first force coincides with the Lorentz force, therefore the radial drift in rings is similar to the gradient drift of plasma in the magnetic field. The second force is produced by the wave generated by the nearby satellite in the resonance position. In inertial systems, the second force alone causes a matter flow in its direction, called acoustic streaming. Since the radial drift is caused by nonlinear time-averaged force of high-frequency harmonic interactions in the wave, it exists in the wave propagation zone: from the birth place of the wave-the resonance position, up to the reflection point of the wave, where its group velocity vanishes. Our estimations show that the size of the density wave propagation zone corresponding to the density wave which had been formerly generated the 2:1 orbital resonance with Mimas is consistent with the width of the Cassini Division. In our case the nature of the radial drift is such that first of all it clears out the farthest from the resonance position; later, the closer areas also get affected by the drift. The zone closest to the resonance position itself is the last to be involved in the process. The matter carried away by the drift is partially accumulated near the resonance position forming a narrow dense ringlet. (c) 1996 American Institute of Physics.

Journal Article↗

PubMed1992

Gene-culture coevolution: toward a general theory of vertical transmission.

A general formulation of cultural and genetic transmission is developed. The cultural transmission is vertical and the genetics may involve multiple loci. Each individual is represented by a phenogenotype, and conditions are given under which the evolutionary dynamics of phenogenotype frequencies are reducible to phenogametic or phenoallelic frequencies. The interaction between genes and culture is specified by an association measure, and results on the order of magnitude of this association at equilibrium are presented.

Biological Evolution↗

PubMed1983

Gaze and mutual gaze of preschool children in conversation.

The study was designed to describe the functional significance of gaze and mutual gaze in the context of the free-play conversation of preschool children. It was hypothesized that mutual gaze is not a fortuitous event in young children but a result of a gaze-action-gaze-reaction sequential process. Eleven high- and 11 low-friendship dyads were formed on the basis of the frequency of interaction in freeplay. Each dyad was videotaped for 15-minute play sessions. The videotapes were analyzed for the occurrence of gaze-related utterances and the occurrence of mutual gaze. When the speaker gazed at the listener the contingent probability of gaze response in the listener was 45% (as compared to a base rate of 3% gaze-related utterances). When the listener gazed at the speaker, the probability of gaze response was 38%. Gaze-related utterances were longer, more likely to result in a relevant response from the listener and less likely to result in nonresponse than utterances unaccompanied by gaze. Friendship between dyad members had no effect on any of the measures. It was concluded that gaze and mutual gaze are systematic components of the conversational behavior of preschool children.

Attention↗

PubMed1989

Insert-type hearing protector stability as a function of controlled jaw movement.

Samples of five insert-type hearing protectors (three viscose foam, one poly-flanged, and one glass fiber) were evaluated for change in attenuation as a result of 30 min of controlled jaw movement. Protected-ear, narrow-band noise thresholds were obtained at octave intervals (between 0.25 and 4.0 kHz) before and after the jaw-movement activity. Frequency and interaction effects were not significant. Protector effects were significant beyond the 0.01 level of probability that chance caused the observed differences. As a group, the viscose foam protectors were more stable than the others. The most stable protector was E.A.R., and the least stable was Bilsom Soft.

Adult↗

PubMed2002

The ecology of individuals: incidence and implications of individual specialization.

Most empirical and theoretical studies of resource use and population dynamics treat conspecific individuals as ecologically equivalent. This simplification is only justified if interindividual niche variation is rare, weak, or has a trivial effect on ecological processes. This article reviews the incidence, degree, causes, and implications of individual-level niche variation to challenge these simplifications. Evidence for individual specialization is available for 93 species distributed across a broad range of taxonomic groups. Although few studies have quantified the degree to which individuals are specialized relative to their population, between-individual variation can sometimes comprise the majority of the population's niche width. The degree of individual specialization varies widely among species and among populations, reflecting a diverse array of physiological, behavioral, and ecological mechanisms that can generate intrapopulation variation. Finally, individual specialization has potentially important ecological, evolutionary, and conservation implications. Theory suggests that niche variation facilitates frequency-dependent interactions that can profoundly affect the population's stability, the amount of intraspecific competition, fitness-function shapes, and the population's capacity to diversify and speciate rapidly. Our collection of case studies suggests that individual specialization is a widespread but underappreciated phenomenon that poses many important but unanswered questions.

Animals↗

PubMed2003

Internet gambling: issues, concerns, and recommendations.

The influence of technology in the field of gambling innovation continues to grow at a rapid pace. After a brief overview of gambling technologies and deregulation issues, this review examines the impact of technology on gambling by highlighting salient factors in the rise of Internet gambling (i.e., accessibility, affordability, anonymity, convenience, escape immersion/dissociation, disinhibition, event frequency, asociability, interactivity, and simulation). The paper also examines other factors in relation to Internet gambling including the relationship between Internet addiction and Internet gambling addiction. The paper ends by overviewing some of the social issues surrounding Internet gambling (i.e., protection of the vulnerable, Internet gambling in the workplace, electronic cash, and unscrupulous operators). Recommendations for Internet gambling operators are also provided.

Behavior, Addictive↗

PubMed2006

Disentangling gender and age effects on risky single occasion drinking during adolescence.

OBJECTIVES: To determine the association between adolescent risky single occasion drinking (RSOD) and gender, age, and the relative age position of students within their class. METHOD: A cross-sectional national representative sample of 7088 from 8th to 10th graders in Switzerland (mean age 14.6; SD = 0.94) as part of the ESPAD international study was analysed using hierarchical linear modelling. RESULTS: Being male, older than the class average and a member of older classes (on average) was associated with a higher RSOD frequency. Additionally, interactions between student and class level were found. The higher the mean class age the greater the difference in RSOD between boys and girls, and the lower the impact on RSOD of the relative age position in a class. CONCLUSIONS: In early and mid-adolescence, prevention efforts should try to impede the modelling of alcohol use of older classmates, whereas in late adolescence gender-specific motives for RSOD should be taken into account.

Adolescent↗

PubMed2002

Interactive effects of high-frequency oscillatory ventilation and inhaled nitric oxide in acute hypoxemic respiratory failure in pediatrics.

OBJECTIVE: High-frequency oscillatory ventilation (HFOV) and inhaled nitric oxide (iNO) have been reported to improve oxygenation in children with acute hypoxemic respiratory failure (AHRF), but their roles in the treatment of AHRF remains unknown. The use of HFOV improves oxygenation by increasing lung recruitment. iNO can improve oxygenation in AHRF, but it may have limited efficacy in patients with poor lung inflation. Based on these findings, we hypothesized that the combined treatment of HFOV and inhalation of low-dose NO would improve oxygenation and survival in children with severe AHRF compared with children treated with conventional mechanical ventilation (CMV) or either treatment alone. SETTING: Tertiary pediatric intensive care units at seven academic centers. DESIGN: Post hoc analysis of data from children enrolled in a multicenter, randomized, masked study of the use of iNO in the treatment of AHRF. PATIENTS: A total of 108 pediatric patients with AHRF defined as an oxygenation index of >15 twice within 6 hrs. Mode of ventilation (HFOV or CMV) was determined by the patient's physician based on guidelines to maximize oxygenation. The patient was then randomized to treatment with or without iNO. Comparisons were made between patients who were treated with HFOV plus iNO (n = 14), HFOV alone (n = 12), CMV plus iNO (n = 35), and CMV alone (n = 38). INTERVENTIONS: Ventilation with CMV or HFOV with or without iNO. MEASUREMENTS AND MAIN RESULTS: We found that the change in Pao /Fio ratio was greatest in the HFOV plus iNO group compared with the other treatment groups at 4 hrs (p =.02) and 12 hrs (p =.01). After 24 hrs of treatment, both HFOV plus iNO and HFOV alone resulted in greater improvement in Pao2/Fio2 ratio than either CMV alone or CMV plus iNO (p =.005). After 72 hrs, treatment with HFOV alone resulted in a greater improvement in Pao2/Fio2 ratio than either CMV alone or CMV plus iNO (p =.03). There was no difference in predefined treatment failures between treatment groups. CONCLUSIONS: We conclude that the combination of HFOV with iNO causes a greater improvement in oxygenation than either treatment strategy alone in children with severe AHRF. We speculate that the enhanced lung recruitment by HFOV enhances the effects of low dose iNO on gas exchange.

Administration, Inhalation↗