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PubMedDate not supplied

Mothers' time with infant and time in employment as predictors of mother-child relationships and children's early development.

This study tested predictions from economic and developmental theories that maternal time with an infant is important for mother-child relationships and children's development, using time-use diaries for mothers of 7- to 8-month-old infants from the National Institute of Child Health and Human Development Study of Early Child Care (N = 1,053). Employment reduced time with infants, but mothers compensated for some work time by decreasing time in other activities. With family and maternal characteristics controlled, time with infants predicted high Home Observation for Measurement of the Environment (HOME) scores and maternal sensitivity, but bore little relation to children's engagement with mothers, secure attachment, social behavior, or cognitive performance from 15 to 36 months. Mothers who spent more time at work had higher HOME scores. Maternal time with infants may reflect maternal characteristics that affect both time allocation and maternal behavior.

Adolescent↗

PubMed2026

Characterizing Time Toxicity in Lung Cancer Clinical Trials: Development and Application of a Novel Time Burden Metric.

PURPOSE: Participation in clinical trials imposes additional time commitments beyond routine care; however, trial-associated time toxicity (TT) remains underinvestigated and poorly characterized. The purpose of this study was to develop a scalable, procedure-based metric to quantify total time required for trial participation using the protocol schedule of events. We applied this framework to lung cancer clinical trials to estimate trial-associated burden and explore changes in TT over time. MATERIALS AND METHODS: Protocols for clinical trials associated with United States (US) Food and Drug Administration (FDA) approvals of oral lung cancer therapies were obtained from public sources. Using each protocol's schedule of events, study-mandated procedures were assigned time toxicity units (TTUs) based on standardized time estimates. TTUs for each procedure were multiplied by their frequency and summed for screening through cycle 5 to determine a trial's total time toxicity (TTT). Days with health care contact (DHC) were summed over the same period to determine total DHC (TDHC). Median (m) TTT and TDHC were compared between studies published in 2005-2014 and 2015-2024 to assess temporal trends. Two-sample Mann-Whitney U tests were used for nonparametric comparisons. RESULTS: Thirty-two phase-specific protocols from trials published between 2005 and 2024 were included. Among studies published in 2005-2014 (n = 7), the median TTT (mTTT) was 63.8 (41.8-109.3) versus 82 (50.3-139.5) in 2015-2024 (n = 25) (P = .042). Corresponding median TDHC values were 14 (10-21) versus 15 (11-44), respectively (P = .16). CONCLUSION: More contemporary studies demonstrated higher TTT, with significantly greater mTTT observed in studies published in 2015-2024 versus 2005-2014. TDHC demonstrated less sensitivity in capturing differences in time burden. These findings demonstrate the feasibility and practical applicability of the proposed TT framework for characterizing protocol-associated time burden. Prospective validation and broader implementation may help inform patients and encourage streamlined protocol development.

Journal Article↗

PubMed1984

Time-dependent inhibition of prostaglandins synthesis by nonsteroidal antiinflammatory drugs; time-dependent alteration of inhibitory effect and characteristics of its active site.

The characteristics of the time-dependency of nonsteroidal antiinflammatory drugs (NSAIDs) and their active sites in inhibiting cyclooxygenase activity were investigated using bovine seminal vesicle microsomal fraction. The Hill's coefficients of the inhibition curve of most NSAIDs were approximately 1.0, except for some drugs which had Hill's coefficients that were obviously more than 1.0. The values for indomethacin, diclofenac and flurbiprofen were approximately 1.5, 1.7 and 2.0, respectively. A time-dependent cyclooxygenase inhibiting effect was observed only with the NSAIDs in the group which had Hill's coefficients that were significantly more than 1.0. A time-dependent increase in inhibiting activity of these drugs was observed by the change in the inhibition curve. Time-dependently, the Hill's coefficient of the curve of the NSAIDs approached 1.0 from more than 1.0. With this change, the shift of the curve to the left was also observed time-dependently. These changes in the curve were no longer seen when the Hill's coefficient dropped to 1.0. These time-dependent effects were protected by salicylic acid, which did not have any effect on cyclooxygenase activity in vitro, in a dose-dependent manner. These results suggested that the two classes of NSAIDs, time-dependent and non-time-dependent, are clearly differentiated by the slope of the inhibition curve of NSAIDs. Furthermore, the present results indicate that the degree of time-dependence of the NSAIDs depends on the Hill's coefficient of the inhibition curve, and the value is important for the potency of the cyclooxygenase inhibition, in addition to the affinity for the catalytic site of the enzyme.

Animals↗

PubMed1970

Interresponse time duration in fixed-interval schedules of reinforcement: control by ordinal position and time since reinforcement.

The times between each of the first thirteen responses after reinforcement (the first twelve interresponse times) were determined for two pigeons whose pecking was reinforced on fixed-interval schedules of food reinforcement ranging from 0.5 min to 5 min. These interresponse times were classified with respect to their ordinal position in the sequence of responses and with respect to the time since the preceding reinforcement at which the initiating response occurred. The median interresponse time durations were essentially constant after the sixth response after reinforcement regardless of the time at which the interresponse time was initiated. The durations of the first few interresponse times after reinforcement decreased as the number of preceding responses increased and as the time since the preceding reinforcement increased.

Journal Article↗

PubMed1976

[Relationship between the proliferation waves of the hepatocytes after hepatectomy and the waves of diurnal rhythm of mitotic activity. 1. Dependence of the form of the mitotic wave and the time of attaining its maximal degree on the time of operation].

The diurnal rhythm of mitotic activity (MA) of intact animal hepatocytes and the proliferative wave of hepatocytes after partial hepatactomy at time t0 are thought to appear as a result of formation of an initial proliferative wave, Pk-wave, within the G0-phase at constant moments of the day--time tk+1=tk+TMA(TMA=24hrs/K, k=1, or 2, . . ., or K) under the influence of the regulating system of the organism. Cells of the Pk-wave pass during a short time deltat (deltat less than TMA) from the G0-phase into the transformation phase, and then into the G1-phase. The 1st stimulated proliferative wave is formed at time tk, if tk--TMA less than t0 less than or equal to tk; its intensity depends most likely on the intensity of the corresponding Pk-wave of the intact liver. It was noted that time t0 of partial hepatectomy was necessary to coordinate with tk, but not with the time of the maximal mitotic activity, and that it was necessary to hepatectomize all animals within the interval from time tk--TMA to time tk. The model was shown to compare well with data by Post et al. (1963), Barbason (1970), and Van Cantfort and Barbason (1972) for hepatocytes of Wistar rats with TMA=8hrs, and tk (k=1,2,3) within intervals (2 a.m.; 4 a.m), (10 p.m.; noon), and (6 p.m. 8 p.m.). The maximal rate of liver generation was observed for all the hepactomized animals with the time of operation being between 8 p. m. and 2 a.m.

Animals↗

PubMed1997

Display technique using time-dependent scatter diagrams for the study of changing relative timings of three spike trains: evaluation of functional connectivity in a local area of the nervous system.

The relative timings of impulses caused by two neurons can be studied using cross-correlation techniques or the related techniques of the joint peristimulus-time histogram and the time-dependent correlation function. Analysis of the relative timings of several related neurons is important to the study of the dynamics, since we consider functional connectivity to be partially related to the dynamics. Functional connectivity changes of short duration reflect physiological functions rather than changes of synaptic connections. The relative timings of impulses are considered to reflect functional connectivity. Using the joint impulse configuration scatter diagram (JICSD) proposed by Perkel, a time-dependent scatter diagram (TDSD) is calculated to analyze the change of functional connectivity. The JICSD displays the long-time average of relative timings of impulses or the functional connectivity of three interconnected neurons. We generated JICSDs for short durations and we subsequently generated TDSDs by arranging JICSDs in chronological order. The change of a "snowflake pattern" of each JICSD was interpreted in terms of change of the functional connectivity. We propose a method for analyzing the changing functional connectivity among three neurons.

Action Potentials↗

PubMed2002

Characterization of neonatal personnel time inputs and prediction from clinical variables--a time and motion study.

OBJECTIVE: To characterize and predict personnel time inputs to neonatal intensive care using infant characteristics from chart review. STUDY DESIGN: For 12 hours each day, observers timed all direct care, charting, discussions, and procedures for 154 infants. Time inputs were correlated with 40 infant characteristics and resource markers, as well as the Score for Neonatal Acute Physiology (SNAP) for that day of care. RESULTS: Nurses accounted for 76%, respiratory therapists 8%, fellows 5%, nurse practitioners 7% and attendings 5% of total time invested in patient care. Nurses and respiratory therapists spent proportionately more time in direct patient care. In regression models, a limited number of variables explained 36% of the variance in time input per patient for respiratory therapists (p<0.0001), 42% for nurses (p<0.0001), and 23% for physicians and nurse practitioners (p<0.0001). CONCLUSIONS: Total labor inputs can be accurately predicted through the use of a limited number of clinical characteristics. This technique should be routinely employed to improve the accuracy of economic evaluations. Nursing accounts for the majority of time invested in neonatal care. Improved efficiency in neonatology is thus most likely to be generated by interventions that reduce direct nursing time.

Health Personnel↗

PubMed2000

Time perception in boys with attention-deficit/hyperactivity disorder according to time duration, distraction and mode of presentation.

In a recent theoretical model of attention-deficit/hyperactivity disorder (ADHD), Barkley (1997a) predicted that ADHD children experience impairments in their psychological sense of time. This was demonstrated in a series of experiments by Barkley, Koplowicz, Anderson, and McMurray (1997). The present study sought to investigate the effects of ADHD subtype, stimulus duration, mode of presentation (visual versus auditory) and distractors on the performance of a simple time reproduction task. Data were obtained from 44 ADHD children (14 predominantly inattentive and 30 combined type) and 44 age-matched Controls using the Time Perception Application version 1.0 (Barkley, University of Massachusetts Medical Center, 1998). Results revealed that the ADHD children made significantly larger errors on Visual time reproduction tasks than the Controls, regardless of ADHD subtype or the presence of distractors. Furthermore, ADHD children were more likely to overestimate the shorter time intervals (0.5 and 2 s) and underestimate the longer time intervals (3, 4 and 6 s) relative to Controls. No group differences were observed on the auditory time reproduction task, with both ADHD and Control groups consistently underestimating the durations to be reproduced. The results of this study provide further support for the prediction that children with ADHD have an impaired sense of time.

Acoustic Stimulation↗

PubMed1996

Choice of time-headway in car-following and the role of time-to-collision information in braking.

Time-headway (THW) during car-following and braking response were studied in a driving simulator from the perspective that behaviour on the manoeuvring level (e.g. choice of THW) may be linked to operational competence of vehicle control (e.g. braking) via a process of adaptation. Time-headway was consistent within drivers and constant over a range of speeds. Since time-headway represents the time available to the driver to reach the same level of deceleration as the lead vehicle in case it brakes, it was studied whether choice of time-headway was related to skills underlying braking performance. The initiation and control of braking were both affected by time-to-collision (TTC) at the moment the lead vehicle started to brake. This strongly supported the idea that time-to-collision information is used for judging the moment to start braking and in the control of braking. No evidence was found that short followers differ from long followers in the ability to accurately perceive TTC. There was, however, evidence that short followers are better able to programme the intensity of braking to required levels. Also, short followers tuned the control of braking better to the development of criticality in time during the braking process. It was concluded that short followers may differ from long followers in programming and execution of the braking response.

Accidents, Traffic↗

PubMed1993

Correction for apparent prolongation of mean transit time resulting from response time in a thermodilution system.

We investigated a method of correcting an apparent prolongation in the measured mean transit time (MTT), resulting from the response time of the thermodilution system. We measured the mean response times (MRT) for five commercially available thermistor-tipped catheters by recording their step function response curves. MRT is the sum of the time from the point of step change to the point of the first detection of change in temperature (latency time) plus the time from the first detection to the point of 63.2% of full response (time constant). By using a flow loop model filled with saline through a mixing chamber, we recorded pairs of thermodilution curves simultaneously with pairs of catheters, and studied the influence of MRT on MTT over the constant flow rates of 1-6 L/min. The difference in MRT's (delta MRT, second) between a pair of thermodilution systems correlated with the difference in MTT's (delta MTT, second) between a corresponding pair of thermodilution curves, yielding an equation: delta MTT = 1.07 delta MRT = 0.04 (n = 72, r = 0.95), delta MTT/delta MRT = 1.02 +/- 0.18 (mean +/- SD). We conclude that an apparent prolongation of MTT due to response time is removable by subtracting MRT from measured MTT.

Bias↗

PubMed1994

The influence of N-acetylcysteine on the measurement of prothrombin time and activated partial thromboplastin time in healthy subjects.

The purpose of the study was to evaluate whether the infusion of N-acetylcysteine decreased the measurement of prothrombin time and activated partial thromboplastin time (APTT) in healthy persons. N-acetylcysteine was administered intraveneously 10 mg kg-1 as a loading dose and then at a rate of 10 mg kg-1 h-1 for 32 h in six male subjects. The intrinsic, extrinsic and common pathway of coagulation were monitored with activated partial thromboplastin time (APTT), and prothrombin time, respectively. In addition, the extrinsic coagulation pathway was monitored with the clotting activity of single factors II, VII, and X. No effect on the intrinsic coagulation pathway was observed. There was a significant and rapid decrease in prothrombin time. Coagulation factors II, VII and X, the three components of prothrombin time, decreased significantly to different degrees. We conclude that infusion of N-acetylcysteine intraveneously decreases the prothrombin time in healthy subjects. Thus, one should not make conclusions which are too far-reaching based on prothrombin time alone in patients who have been treated recently with N-acetylcysteine intraveneously.

Acetylcysteine↗

PubMed1980

The effect of infusion time on the time course of drug concentration in blood.

We have studied by digital computer stimulation the relationship among the rate of intravenous infusion of the dose of a drug, the pharmacokinetic parameters of the drug, the maximum blood drug concentration achieved (Cmax) and the interval (TEff) during which the blood concentration of the drug is maintained above a selected minimum effective concentration (CEff) for the case of single dose administration of a drug with monoexponential pharmacokinetics. It was found that increasing the time during which the dose of the drug is infused results in a much smaller decrease in the maximum blood concentration attained. TEff, was found to be a fraction of the ratios infusion time/drug elimination half-life and zero-time intercept (Co)/CEff. The stimulations showed that TEff varies nonlinearly with increasing infusion time. However, the nature of the relationship between TEff and infusion time depends very much on the value of Co/CEff. At low values of Co/CEff, TEff decreased almost linearly with increasing infusion time, but at higher values of Co/CEff, TEff increased for a time with increasing infusion time. From these simulations, it should be possible to predict whether therapeutically effective blood concentrations of a drug may be achieved with the use of a slower infusion in situations where clinical considerations necessitate that the infusion time of the dose be increased.

Computers↗

PubMed1994

Peak time difference of time-density curve in contrast media transit as an indicator of asymmetric cerebral perfusion.

Time-density curve study in contrast media transit has a theoretical possibility to evaluate asymmetric cerebral perfusion. We studied the right-to-left hemispheric difference of peak time in regional time-density curve. Twenty-seven chronic stroke patients underwent either dynamic CT or intravenous digital subtraction angiography (IVDSA), and single photon emission CT (SPECT). We placed symmetric regions of interest as appropriate in each study, and obtained a peak time of each regional time-density curve in IVDSA or dynamic CT, and a laterality index of reconstructed counts in SPECT. Right-to-left difference of peak time significantly correlated to the laterality index both in IVDSA and dynamic CT (r = -0.88, p < 0.001, and r = -0.82, p < 0.001, respectively). Thus, time-density curve study well reflected unilateral reduction of cerebral perfusion. Recent progress in acute thrombolytic intervention for ischemic stroke recommends a quick and efficient evaluation of ischemic status, and time-density curve study may satisfy this requirement.

Angiography, Digital Subtraction↗

PubMed1993

Displacement Rheometer: a method of measuring working time and setting time of elastic impression materials.

A new method of measuring both working time and setting time of elastomeric impression materials has been developed. A Displacement Rheometer was used to monitor the development of elasticity in setting elastomers. The results obtained with the Displacement Rheometer were compared to the results of the ISO test as well as those of the Controlled Stress Rheometer. Working time using the ISO method was calculated according to the standard method described in the specification, while for both the Controlled Stress Rheometer and the Displacement Rheometer working times were the times when initial elastic recovery was observed at 23 degrees C. With the Displacement Rheometer the setting time is the time when the mixed material reaches optimal elastic recovery at 37 degrees C. Statistical analysis with ANOVA showed that for five of the test materials there were no differences between the three methods. For three of the materials the working time determined by the ISO method was significantly longer than that determined by the other two methods. The advantages and disadvantages of each method are discussed and the Displacement Rheometer is recommended as a supplement to the standard specification method.

Alginates↗

PubMed2006

Time of death dependent criteria in vitreous humor: accuracy of estimating the time since death.

Since more than 40 years reports on the rise of potassium concentration [K(+)] in vitreous humor have been published with different statements concerning the accuracy of death time estimation. In the last years several statistical approaches for a more accurate estimation of the time since death have been reported. While in most investigations the PMI has been used as the independent and [K(+)] as the dependent variable in linear regression analysis between PMI and [K(+)], recently it has been suggested to use [K(+)] as the independent variable for regression analysis. Changing the variables would lead to a higher accuracy of death time estimation. This has also been recommended for regression analysis between hypoxanthine concentration [Hx] and time since death. This hypothesis has been checked on independent cases with potassium and hypoxanthine in vitreous humor. Linear regression with [K(+)] or [Hx] as independent variable has revealed a slightly more accurate death time estimation compared to a linear regression with PMI as independent variable. Thus, e.g. the accuracy could have been improved from +/-25.96 to +/- 23.27h by using [K(+)] as independent variable. Another statistical approach has re-evaluated six large studies on the rise of vitreous [K(+)] using a local regression analysis (Loess procedure). Based on this re-evaluation an accuracy of death time estimation has been recommended (95% limits of confidence of +/-1h in the early PMI and +/-10h, 110h postmortem) which has surpassed even optimistic results of earlier investigations. This recommended accuracy of death time estimation has been checked on a random sample of 492 cases. Only 153 cases have been within the predicted postmortem interval, 339 lay outside with a systematic overestimation of the time since death.

Chromatography, High Pressure Liquid↗

PubMed2005

Propagation of onset and peak time of myocardial shortening in time of myocardial shortening in ischemic versus nonischemic cardiomyopathy: assessment by magnetic resonance imaging myocardial tagging.

OBJECTIVES: We aimed to study the relation between onset and peak time of circumferential shortening and the direction of propagation of these parameters in both ischemic and nonischemic patients. BACKGROUND: Peak time is often used to select patients for cardiac resynchronization therapy, whereas pacing influences only the onset times directly. Furthermore, it is unclear whether there is a consistent direction of propagation delay and whether this depends on the etiology. METHODS: Magnetic resonance imaging myocardial tagging with high temporal resolution (14 ms) was applied to 29 patients (18 nonischemic, 11 ischemic) and 17 healthy control subjects. Time to onset (T(onset)), to first peak (T(peak,first)), and to maximum peak (T(peak,max)) of circumferential shortening were determined. Three-dimensional vectors were calculated to denote the main direction of asynchrony. RESULTS: In both patient groups, T(onset) showed a significant positive relation with both T(peak,first) and T(peak,max); however, T(peak,first) correlated considerably better with T(onset) than did T(peak,max) (p < 0.0001 for nonischemic, and p < 0.01 for ischemic patients). Moreover, the relations between T(peak) and T(onset) were stronger in the nonischemic patients than in the ischemic patients (p < 0.001). In nonischemic patients, the propagation of T(onset) was consistently from septum to lateral wall. In the ischemic patients, however, no consistent direction of propagation was found. For both groups, the longitudinal propagation delays (between apex and base) were negligible compared with the short-axis delays. CONCLUSIONS: The relation between peak time and onset time of shortening is strongest in nonischemic patients and is most consistent when time to first peak is used (instead of time to maximum peak).

Aged↗

PubMed2005

Time matters; what is the time in your defibrillator? An observational study in 30 emergency medical service systems.

BACKGROUND: Measuring different intervals during cardiopulmonary resuscitation is a key element of resuscitation performance. For accurate time measurements, the internal clocks of automated external defibrillator (AEDs) need to be synchronized with the dispatch centre time. AIM: To determine the present practice of using and synchronizing the AED clocks in five regions in Finland. METHODS: During a single morning, the time of all AED clocks in the emergency medical service (EMS) systems of five large hospital districts were checked and compared with the dispatch centre time. A questionnaire about synchronisation policy and documentation of the first defibrillatory shock was also e-mailed to the local EMS medical supervisors. RESULTS: Eighty-eight AEDs were checked in 30 EMS systems. The mean deviation from dispatch centre time was 412 (+/-1001) s. There was no difference between EMS systems with (N = 7) or without (N = 23) written guidelines regarding synchronisation. Many EMSs reported that they document the time of the first shock without synchronisation of clocks. CONCLUSIONS: Synchronisation of AED clocks is not widespread in Finland. Instructions to synchronize have been issued in a minority of EMS systems. Despite this, time deviations are large, and erroneous times are recorded.

Cardiopulmonary Resuscitation↗

PubMed1999

Time-resolved fluorescence anisotropy study of the refolding reaction of the alpha-subunit of tryptophan synthase reveals nonmonotonic behavior of the rotational correlation time.

Time-resolved fluorescence anisotropy of a bound extrinsic probe was studied in an effort to characterize dynamic properties of the transient partially folded forms that appear during the folding of the alpha-subunit of tryptophan synthase (alphaTS) from Escherichia coli. Previous studies have shown that alphaTS, a single structural domain, can be cleaved into autonomously folding amino- and carboxy-folding units comprising residues 1-188 and 189-268, respectively [Higgins, W., Fairwell, T., and Miles, E. W. (1979) Biochemistry 18, 4827-4835]. By use of a double-kinetic approach [Jones, B. E., Beechem, J. M., and Matthews, C. R. (1995) Biochemistry 34, 1867-1877], the rotational correlation time of 1-anilino-8-naphthalene sulfonate bound to nonpolar surfaces of folding intermediates was measured by time-correlated single photon counting at varying time delays following initiation of folding from the urea-denatured form by stopped-flow techniques. Comparison of the rotational correlation times for the full-length alphaTS and the amino-terminal fragment suggests that folding of the amino-terminal fragment and carboxy-terminal fragment is coordinated, not autonomous, on the milliseconds to seconds time scale. If a spherical shape is assumed, the apparent hydrodynamic radius of alphaTS after 5 ms is 26.8 A. The radius increases to 28.5 A by 1 s before decreasing to the radius for native alphaTS, 24.7 A, on a longer time scale (>25 s). Viewed within the context of the kinetic folding model of alphaTS [Bilsel, O., Zitzewitz, J. A., Bowers, K. E. , and Matthews, C. R. (1999) Biochemistry 38, 1018-1029], the initial collapse reflects the formation of an off-pathway burst-phase intermediate in which at least part of the carboxy folding unit interacts with the amino folding unit. The subsequent increase in rotational correlation time corresponds to the formation of an on-pathway intermediate that leads to the native conformation. The apparent increase in the radius for the on-pathway intermediate may reflect a change in the interaction of the two-folding units, thereby forming a direct precursor for the alpha/beta barrel structure.

Anilino Naphthalenesulfonates↗