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Results for “interaction frequencies”

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PubMed1992

Mechanisms of electromagnetic interaction with cellular systems.

The question of how electromagnetic fields--static or low to high frequency--interact with biological systems is of great interest. The current discussion among biologists, chemists, and physicists emphasizes aspects of experimental verification and of defining microscopic and macroscopic mechanisms. Both aspects are reviewed here. We emphasize that in certain situations nonthermal interactions of electromagnetic fields occur with cellular systems.

Animals↗

PubMed2003

The role of drinking in suicidal ideation: analyses of Project MATCH data.

OBJECTIVE: The associations of suicidal ideation with both the intensity (drinks per drinking day) and frequency of alcohol consumption were examined in a longitudinal study of treated alcoholics. METHOD: The data are from alcohol dependent subjects (1,187 men and 374 women) enrolled in Project MATCH, a multisite clinical trial of psychosocial treatments of alcoholism. Multivariate analyses for correlated data using generalized estimating equation approaches were performed to examine correlates of suicidal ideation at study entry and at 3-, 9- and 15-month follow-up. Analyses were stratified by gender and controlled statistically for depression and alcoholism severity. RESULTS: Suicidal ideation was common among women (15.5%) and men (9.9%) entering treatment, and at least 3.6% of women and 4.2% of men reported suicidal ideation at each follow-up. There were gender patterns in suicidal ideation. In women, intensity was associated with suicidal ideation, but even nonintense drinking became associated with suicidal ideation with more frequent drinking (intensity-frequency interaction). In men, intensity was also associated with suicidal ideation, whereas frequency was unrelated. Antisocial personality disorder in men but not in women, and depression in both groups, were also linked to suicidal ideation. CONCLUSIONS: Suicidal ideation is prevalent among treated alcoholics. Drinking is strongly associated with suicidal ideation and in women even light drinking, if it occurs regularly, is associated with suicidal ideation, with implications for suicide risk-recognition and intervention.

Adult↗

PubMed1998

Spatial-frequency discrimination, brain lateralisation, and acute intake of alcohol.

The effect of alcohol (breath-alcohol level of 0.1%) on perceptual discrimination of low (1.5 cycles deg-1) and high (8 cycles deg-1) spatial frequencies in the left and right visual field was measured in eighteen right-handed males, in a double-blind, balanced placebo design. Discrimination thresholds for briefly (180 ms) presented sinusoidal gratings were determined by two-alternative forced-choice judgments with four interleaving psychophysical staircases providing random trial-to-trial variation of reference spatial frequency and visual field, in addition to a random (+/- 10%) jitter of reference spatial frequency. Alcohol produced overall higher discrimination thresholds but did not alter the visual-field balance: no main effect of visual field was observed, but in both placebo and alcohol conditions spatial frequency interacted with visual field in the direction predicted by the spatial-frequency hypothesis of hemispheric asymmetry in visual-information processing, with left-visual-field/right-hemisphere superiority in discrimination of low spatial frequencies and right-visual-field/left-hemisphere superiority in discrimination of high spatial frequencies.

Adult↗

PubMed1982

Integrating hearing and deaf preschoolers: an attempt to enhance hearing children's interactions with deaf peers.

In this study, an attempt was made to modify hearing preschoolers' frequent and persistent refusal to interact with profoundly deaf peers. Half of the hearing children involved in a low-key mainstreaming program participated in a special 3-week training program that included discussions about the meaning of deafness, an opportunity to practice communication techniques effective with deaf children, and free-play interactions with deaf children. Prior to the intervention, no differences were found in the treatment and control children's interaction frequencies and duration or in the types of acts used to initiate interactions. Significant differences were found, however, following the heightened involvement. Hearing treatment children began interacting significantly less with the deaf children than did hearing control children. Hearing treatment children also became less responsive to the deaf children's attempts to interact than were hearing control children. While it was hypothesized that increased exposure would result in hearing treatment children using more gestures, touches, and messages incorporating multiple modalities, they came to use significantly fewer of these acts than did the hearing control children. The deaf children remained relatively unaffected by the intervention. These results are discussed in terms of their relevance for other mainstreaming programs and for research on the growth of social competence in general.

Child Behavior↗

PubMed1988

Interactions among spatial frequency and orientation channels adapted concurrently.

Interactions between size and orientation-specific mechanisms in the human visual system were investigated using a sequential adaptation technique. Subjects adapted to a vertical, 4 c/deg high-contrast (0.7) sinewave grating that was interleaved at a rate of 0.5 Hz with another adapting grating differing either in (1) spatial frequency or (2) orientation. Before and after adaptation contrast thresholds were measured for a vertical 4 c/deg sinewave test grating. The resultant elevation in contrast threshold was plotted as a function of the (1) spatial frequency or (2) orientation differences between the first and second adapting gratings. Maximum threshold elevation was found when both adapting gratings shared the same spatial frequency and orientation. Minimum elevations were found when the second grating's spatial frequency or orientation differed by approx. 1.5 octaves or 45 deg, respectively. Beyond these values threshold elevations reapproached the baseline value measured in a control condition, where the 4.0 c/deg adapting grating was interleaved with a blank. The minimum threshold elevations were 0.2-0.3 log units below the baseline level. The results suggest the existence of inhibitory interactions between neural mechanisms tuned to the size and orientation of retinal images.

Adaptation, Ocular↗

PubMed1986

Interactive play: the frequency of related verbal responses.

The potential relationship between interactive play and the frequency of related responding to comments was investigated within the dyadic interactions among a 4-year-old Specifically Language Impaired (SLI) boy and normal-language users. The normal-language users were of similar chronological age or language level to the SLI boy. The results indicated that the SLI boy's frequency of related responding was variable but consistently associated with the following: the ratio of other-directed partner turns in play; the frequency of a particular discourse pattern; and the frequency of shared reference across the discourse pattern. Unlike related responses of the SLI child, the frequencies of related responses of normal children were essentially stable. Implications of the differences are discussed.

Child, Preschool↗

PubMed2005

Factors influencing social interaction among high school students with intellectual disabilities and their general education peers.

Recent legislative, policy, and research initiatives affirm the importance of improving social outcomes for adolescents with moderate to severe intellectual disabilities. Using observational methodology, we examined the influence of level of integration and Peer Buddy proximity on social interaction between students with intellectual disabilities and their general education peers in high school settings. Similarities and differences were found between more and less integrated settings with respect to contextual variables and measures of social interaction. Across settings, the proximity of a Peer Buddy was associated with higher frequency interactions and more positive student affect. Implications regarding increasing social interaction among high school students are discussed.

Adolescent↗

PubMed1989

Elucidation of the nifedipine-quinidine interaction.

Four case reports have been published that document a clinically significant drug interaction between nifedipine and quinidine in patients with left ventricular dysfunction. To define the population at risk and the mechanisms involved in manifestations of this interaction, 12 patients currently treated with quinidine for either ventricular or supraventricular arrhythmias were stratified into two groups based on left ventricular ejection fraction (EF) measurements (group A greater than 35%; group B less than 35%). The interaction was conducted through two phases: oral quinidine (Q) and oral quinidine plus nifedipine (N + Q). Pharmacokinetic modeling of total body clearance (CL) and AUC were assessed for each phase. One patient (group A, 70% EF) exhibited the interaction with a 41% decrease in steady-state serum quinidine concentrations. The patient's AUC and CL were 48.2 micrograms/ml.hr (Q) versus 28.6 micrograms/ml.hr (N + Q) and 94.4 ml/min (Q) versus 159.1 ml/min (N + Q), respectively. There was no difference in AUC or CL between the Q and N + Q phases or between groups A and B for the entire population. The N + Q interaction is not hemodynamically mediated. Clinical consideration of the possibility of this low-frequency interaction should be noted.

Adult↗

PubMed2025

AQuA Tools: clear and reliable BEDPE operations for 3D genomics.

MOTIVATION: The genome interacts with itself within the volume of the cell nucleus to process information. These interactions mediate signal integration, gene regulation, and cell identity. The identification of new therapeutic targets from non-coding disease-associated variants relies critically on correctly assigning variants to genes through 3D interactions. Experimental techniques in 3D genomics, such as HiC and HiChIP, allow the mapping of interactions through sequencing. Bioinformatics for 3D genomics contends primarily with contact matrices that contain interaction frequencies for all possible element pairs, and BEDPE files that store element pairs that interact. Whereas the tools available for processing linear genomic data are mature, operating on contact matrices and BEDPE files remains cumbersome, opaque, and error-prone, as researchers have had to shoehorn tools originally designed for linear data. A genome arithmetic designed from the ground up for 3D genomics does not yet exist. RESULTS: We present AQuA Tools, a suite of shell- and R-based command-line tools that provide a set of core operations on contact matrices and BEDPE files motivated by key questions in population genetics, cancer research, and precision medicine. We have designed our core operations to be clear, reliable, intuitive and versatile. Core operations can be chained together along with standard UNIX commands. Our goal is to make AQuA Tools easy for the novice to learn and the go-to choice for power users. We hope our tools will motivate more researchers to use 3D genomic data in their projects. AVAILABILITY AND IMPLEMENTATION: We provide and maintain AQuA Tools at https://github.com/axiotl/aqua-tools.

Genomics↗

PubMed2004

Ventilatory behavior during sleep among A/J and C57BL/6J mouse strains.

The pattern of breathing during sleep could be a heritable trait. Our intent was to test this genetic hypothesis in inbred mouse strains known to vary in breathing patterns during wakefulness (Han F, Subramanian S, Dick TE, Dreshaj IA, and Strohl KP. J Appl Physiol 91: 1962-1970, 2001; Han F, Subramanian S, Price ER, Nadeau J, and Strohl KP, J Appl Physiol 92: 1133-1140, 2002) to determine whether such differences persisted into non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. Measures assessed in C57BL/6J (B6; Jackson Laboratory) and two A/J strains (A/J Jackson and A/J Harlan) included ventilatory behavior [respiratory frequency, tidal volume, minute ventilation, mean inspiratory flow, and duty cycle (inspiratory time/total breath time)], and metabolism, as performed by the plethsmography method with animals instrumented to record EEG, electromyogram, and heart rate. In all strains, there were reductions in minute ventilation and CO2 production in NREM compared with wakefulness (P < 0.001) and a further reduction in REM compared with NREM (P < 0.001), but no state-by-stain interactions. Frequency showed strain (P < 0.0001) and state-by-strain interactions (P < 0.0001). The A/J Jackson did not change frequency in REM vs. NREM [141 +/- 15 (SD) vs. 139 +/- 14 breaths/min; P = 0.92], whereas, in the A/J Harlan, it was lower in REM vs. NREM (168 +/- 14 vs. 179 +/- 12 breaths/min; P = 0.0005), and, in the B6, it was higher in REM vs. NREM (209 +/- 12 vs. 188 +/- 13 breaths/min; P < 0.0001). Heart rate exhibited strain (P = 0.003), state (P < 0.0001), and state-by-strain interaction (P = 0.017) and was lower in NREM sleep in the A/J Harlan (P = 0.035) and B6 (P < 0.0001). We conclude that genetic background affects features of breathing during NREM and REM sleep, despite broad changes in state, metabolism, and heart rate.

Animals↗

PubMed2003

Gradual frequency rises in interacting black ghost knifefish, Apteronotus albifrons.

The present paper highlights the relationship between social status and production of gradual frequency rises in interacting Apteronotus albifrons. The gradual frequency rise production was mathematically inferred and a discrete classification deliberately avoided. The results showed little gradual frequency rise production before the hierarchy settlement. Afterwards, only the dominant fish kept this gradual frequency rise production at low levels, while the subdominant fish drastically increased it in all following interaction contexts. The hypothesis of gradual frequency rises being involved in communication as submissive signals was thus strengthened.

Animal Communication↗

PubMed2001

Characteristics of closeness in adolescent romantic relationships.

This investigation was designed to describe characteristics of closeness in the romantic relationships of early, mid and late adolescents, and to determine whether adolescent reports of relationship authority and reciprocity are linked to perceptions of interdependence, interaction frequency, activity diversity, influence, and relationship duration. Age was positively associated with interdependence, daily social interaction, weekly activity diversity, and reciprocity but not with influence, authority, or relationship duration; gender was unrelated to all characteristics of closeness. Authority and reciprocity were each positively associated with relationship influence. Authority moderated associations between reciprocity and several characteristics of closeness such that reciprocity was positively linked to interdependence, daily social interaction, and weekly activity diversity, but only in relationships characterized by low levels of authority. Neither reciprocity nor authority was associated with relationship duration.

Adolescent↗

PubMed2003

Modeling the interaction of milking frequency and nutrition on mammary gland growth and lactation.

A mathematical model of biological mechanisms regulating lactation is constructed. In particular, the model allows prediction of the effect of milking frequency on milk yield and mammary regression, and the interaction of nutrition and milking frequency in determining yield. Possible interactions of nutrition with milking frequency on alveolar dynamics are highlighted. The model is based upon the association of prolonged engorgement (as a consequence of milk accumulation) of active secretory alveoli with changes in gene expression that result in impairment and, ultimately, cessation of milk secretion. The emptying of alveoli at milking, following alveolar contraction induced by oxytocin, prevents this process and also allows quiescent alveoli to reactivate. Prolonged engorgement results in apoptosis of the secretory cells and, hence, regression of the mammary gland. Milk yield is linked to alveolar populations, with secretion rates being modulated by nutrition and udder fill effects. The model was used to investigate different management scenarios, and is in agreement with experimental results. The model shows that while milking frequency drives alveolar population, and therefore potential milk production, actual production varies considerably with nutrition. A significant portion of the loss associated with once-daily milking was due to udder fill rather than loss of secretory tissue. The model showed qualitative agreement with experimental data, on the acute and chronic effects of temporary once-daily milking.

Animal Nutritional Physiological Phenomena↗

PubMed1987

Interaction between high frequency jet ventilation and cardiovascular function.

We have studied the interaction of high frequency jet ventilation with cardiovascular pressures and flows. Results in dogs show that the amplitude of all intrathoracic pressures and flows fluctuate with a frequency equal to the difference between the heart rate and ventilator rate. The magnitude of this amplitude variation may be sufficient to obliterate periodically the pulsations in pulmonary artery and right atrial pressures. It is also shown that these cardiovascular beats can occur when the ventilator rate is close to integral multiples of the heart rate. Direct measurement of pleural pressure and the observation that the beats are markedly reduced when the chest is open support the hypothesis that the primary mechanism responsible for these beats is the interaction of the respiratory fluctuations in pleural pressure with the cardiac-generated pressure pulsations.

Animals↗

PubMed1987

Interactions of acoustic and somatosensory evoked responses in a polysensory cortex of the cat.

Interactions of acoustic and somatosensory evoked potentials were studied in the anterior suprasylvian gyrus of the cat. The interactions showed dynamic changes and were susceptible to different kinds of influences. The interactions could be influenced by synchronous activation of the acoustic and somatosensory inputs with 2 Hz frequency, or by elevating the stimulus frequency. Interactions could be influenced by amphetamine and gamma-glutamyl-taurine, drugs known as capable of influencing the arousal level of the brain. The antagonists of amphetamine prevented this effect. Drugs acting on the cortical GABA-ergic system proved also to be decisive in the interactions of evoked potentials of different origins. In some experiments unit activity was recorded parallel with evoked potentials.

Acoustic Stimulation↗

PubMed1982

Word frequency and the intentional-incidental verbal-discrimination learning of nonretarded and mentally retarded individuals.

MA-matched nonretarded and mentally retarded persons were given a verbal-discrimination learning task and an associative matching task. In the verbal-discrimination learning task, word frequency was manipulated by having one-half of the participants in each IQ group pronounce for 20 trials the words that were later used in the verbal-discrimination learning task (i.e., the high-frequency condition). The remaining participants pronounced words that were not a part of the task (i.e., the low-frequency condition). Based on an implication derived from frequency theory, I predicted that retarded persons would be more adversely affected by the high-frequency condition than would nonretarded persons; however, results indicated that both groups were adversely affected. The associative matching task was used to test the incidental learning hypothesis. Results revealed a significant Intelligence X Frequency interaction, which indicated that the retarded group exhibited an incidental learning deficit but only under the high-frequency condition. A possible explanation for this finding was discussed within the context of depth of processing.

Adolescent↗

PubMed1999

Ventilatory frequency variability in spontaneously breathing anaesthetized subjects.

During spontaneous breathing general anaesthesia, inspiration is generally started by a signal related to preceding cardiovascular activity. This phenomenon, 'cardioventilatory coupling', contributes to the variation in ventilatory frequency. However, the detailed, breath-to-breath timing relationship between heart beat and inspiratory onset is complex, with at least four distinct patterns (designated patterns I-IV). These coupling patterns are defined according to the particular breath-to-breath change in: (a) entrainment ratio and (b) coupling interval, the interval between inspiratory onset and the preceding initiating heart beat. We have examined the relationship between coupling and timing of breathing in adult subjects breathing spontaneously during general anaesthesia. The heart rate-ventilatory frequency interaction was explored by identifying the distribution of different coupling patterns in a plot of heart rate vs ventilatory frequency (the HR/f plot) and analysing the variation in breathing frequency during each coupling pattern by differentiating between changes in entrainment ratio from changes in coupling interval. We observed that: (i) coupling patterns are distributed within specific regions of the HR/f plot; (ii) specific patterns of variation in breathing are associated with each coupling pattern; (iii) this variation is a consequence of the balance between changes in entrainment ratio and coupling interval; (iv) coupling was invariably present at low breathing frequencies; and (v) the inverse non-linear relationship between ventilatory frequency and variation is largely a consequence of changing coupling pattern with ventilatory frequency. Coupling explains much of the breath-to-breath variability of ventilatory frequency during anaesthesia, and may be relevant to the phenomena of hypoventilation, central apnoea and ventilatory arrhythmia. A hypothesis concerning the generation of coupling patterns is presented.

Adult↗

PubMed2003

Dispersal rates affect species composition in metacommunities of Sarracenia purpurea inquilines.

Dispersal among local communities can have a variety of effects on species composition and diversity at local and regional scales. Local conditions (e.g., resource and predator densities) can have independent effects, as well as interact with dispersal, to alter these patterns. Based on metacommunity models, we predicted that local diversity would show a unimodal relationship with dispersal frequency. We manipulated dispersal frequencies, resource levels, and the presence of predators (mosquito larvae) among communities found in the water-filled leaves of the pitcher plant Sarracenia purpurea. Diversity and abundance of species of the middle trophic level, protozoa and rotifers, were measured. Increased dispersal frequencies significantly increased regional species richness and protozoan abundance while decreasing the variance among local communities. Dispersal frequency interacted with predation at the local community scale to produce patterns of diversity consistent with the model. When predators were absent, we found a unimodal relationship between dispersal frequency and diversity, and when predators were present, there was a flat relationship. Intermediate dispersal frequencies maintained some species in the inquiline communities by offsetting extinction rates. Local community composition and the degree of connectivity between communities are both important for understanding species diversity patterns at local and regional scales.

Animals↗