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At least 127 records · Page 7Linked to original sources
PubMed2005

Intensive baseball practice improves the Go/Nogo reaction time, but not the simple reaction time.

Baseball hitters are required to make decisions whether to swing or not as quickly as possible. Therefore, we can assume that skilled baseball players have a quicker response. To verify this hypothesis, we assessed the effect of baseball experience or skill levels on simple reaction times and Go/Nogo reaction times in 82 university students (22 baseball players, 22 tennis players, and 38 nonathletes) and 17 professional baseball players. Also, to clarify whether this ability was innate or acquired, we examined the effects of long-term practice for baseball hitting in 94 senior high school students (26 baseball players and 68 non-baseball players). There were no differences in simple reaction time either for sports experience or for skill levels. On the contrary, the Go/Nogo reaction time for baseball players was significantly shorter than that of the tennis players and nonathletes. The Go/Nogo reaction time of higher-skill baseball players was significantly shorter than that of lower-skill players, while that of the professional baseball players was the shortest. The professional players showed the highest (almost linear) correlation between the Go/Nogo reaction time and simple reaction time. A longitudinal study showed that 2 years of hitting practice improved the Go/Nogo reaction time, while the simple reaction time remained constant. A cross-sectional study of high school non-baseball players showed no differences either in the simple or Go/Nogo reaction times in relation to school year. In conclusion, intensive practice, including Go or Nogo decision making, improved the Go/Nogo reaction time, but not the simple reaction time.

Adult↗
PubMed1995

Effects of temperature on bleeding time and clotting time in normal male and female volunteers.

OBJECTIVE: This study was done to assess the effects of temperature on bleeding time and clotting time in normal male and female volunteers. DESIGN: Open study utilizing normal volunteers. SETTING: University research laboratory. SUBJECTS: Fifty-four healthy male and female volunteers, ranging in age from 19 to 35 yrs, who were not receiving medications. The study was done and the samples of venous blood and shed blood collected at the template bleeding time site were obtained at a convenient time for each volunteer. INTERVENTIONS: Skin temperature was changed from +20 degrees to +38 degrees C and blood samples were obtained from the antecubital vein of each volunteer. MEASUREMENTS AND MAIN RESULTS: The effect of local skin temperature ranging from +20 degrees to +38 degrees C on bleeding time was evaluated in 38 normal volunteers (19 male and 19 female). Skin temperature was maintained at +20 degrees to +38 degrees C by cooling or warming the forearm. At each temperature, measurements were made of complete blood count, bleeding time, and thromboxane B2 concentrations in shed blood collected at the template bleeding time site and in serum and plasma isolated from blood collected from the antecubital vein. Clotting time studies were measured in 16 normal volunteers (eight male and eight female) at temperatures ranging from +22 degrees to +37 degrees C. At +32 degrees C, the bleeding time was longer and hematocrit was lower in female than in male volunteers. However, at local skin temperatures of < +32 degrees C, both the males and females exhibited significantly increased bleeding times, which were associated with a reduction in shed blood thromboxane B2. Each 1 degree C decrease in temperature was associated with a 15% decrease in the shed blood thromboxane B2 concentration. Clotting times were three times longer at +22 degrees C than at +37 degrees C. Each 1 degree C reduction in the temperature of the clotted blood was associated with a 15% reduction in the serum thromboxane B2 concentration. CONCLUSION: Our data indicate that during surgical procedures, it is important to maintain normothermia to ensure that platelets and clotting proteins function optimally.

Adult↗
PubMed1998

[Time perception and time estimation in depressive patients].

Subjective time-experience and objective time-estimation were examined in 20 endogenous, 20 neurotic depressives, and 15 healthy volunteers. Subjective experience of past and anticipated future time was more extended in both depressive groups than in healthy controls. Objective time estimation differed between depressives and controls concerning relatively long time spans whereas very short time spans were correctly estimated also by depressives. There were no significant differences between endogenous and neurotic depressives. The perception of extended time normalized during treatment. The depressives' time perception, differences correlated with the extent of depressive psychopathological symptoms and--to a lesser degree--with retardation. The findings support the hypotheses of anthropological phenomenology concerning disturbed time perception and estimation in depressives. Amelioration of experienced time-extension in intentionally structured time spans compared to empty time spans suggests psychotherapeutic consequences in the sense of Lewinsohn.

Adult↗
PubMed2005

Intraoperative cholangiography time in laparoscopic cholecystectomy: timing the radiographer.

BACKGROUND: The debate for and against the routine use of intraoperative cholangiography (IOC) continues. One of the main arguments against the routine use of the technique during laparoscopic cholecystectomy (LC) is the length of time it takes, which in turn increases the cost. In this study, we recorded the time spent by the radiographer providing IOC service in the context of optimizing the utilization of the radiographer and IOC time. METHODS: A total of 91 consecutive LCS, including 19 laparoscopic bile duct explorations, from April 2003 to January 2004 were included in the study. We recorded the time the radiographer took from receiving a call to arriving in the theater, the time he or she spent performing the IOC, and the total time spent in theater. We also recorded the total operative time. RESULTS: The mean time from call to arrival was 9 min (SD = 3, n = 91). The mean total time spent by the radiographer in the theater involved in performing the IOC during LC was 15 min (SD = 8, n = 72), and that during laparoscopic exploration was 46 min (SD = 20, n = 19). The mean operative time was 67 min (SD = 24) and 135 min (SD = 59), respectively. CONCLUSION: Radiographer services as well as IOC time could be optimized to facilitate the routine use of this important technique in LC. Optimizing the logistics and time factor in IOC is an integral component of single-stage management of patients with suspected bile duct stones.

Cholangiography↗
PubMed2003

Reaction time and movement time in patients with carpal tunnel syndrome: an electromyographic study.

OBJECTIVE: To measure the motor performance of the flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles using the parameters electromyographic muscle reaction time and movement time in patients with carpal tunnel syndrome during key turning function. METHOD: A total of 37 female patients with right hand pain were divided into two groups: 21 with an electrophysiologically confirmed diagnosis of carpal tunnel syndrome (Group I), and 16 with normal electrophysiological findings (Group II). The reaction time and movement time values obtained by surface electromyography of the right flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles were compared between groups. RESULTS: Of the 21 patients in Group I, 15 had mild, four moderate, and two severe median nerve lesions. No significant difference between groups was found in the electromyographic reaction time and movement time values of the right flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles during key turning (P>0.05). There was also no significant difference in electromyographic reaction time and movement time between six patients with severe or moderate carpal tunnel syndrome and 15 patients with mild carpal tunnel syndrome in Group I (P>0.05). Sixteen patients in Group II did not have carpal tunnel syndrome. CONCLUSION: The results indicate that patients with and without carpal tunnel syndrome have similar values of reaction time and movement time of the flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles during the pinch grasp function of the hand. RELEVANCE: Muscle reaction time and movement time, and hence the motor performance in electrophysiologically confirmed carpal tunnel syndrome patients appear to have similar parameters in patients with hand pain whose diagnosis were not confirmed with electrophysiologically.

Adult↗
PubMed2000

"To every thing there is a season"--social time and clock time in addiction treatment.

Research on therapeutic interventions and the development or efficacy of treatment services consider 'time' only as a technical, 'objective' condition. Time series analysis and cohort studies describe changes in addiction careers over time, but fail to take into account the role of 'subjective' or 'social time', e.g. the functions of organisational and individual patterns of time use and time budgets. This paper reviews the notion of 'time' in addiction treatment systems. More specifically, the explicit or implicit role played by 'the time factor' in specific types of treatment such as '12-step programs', in-patient, out-patient care and individual treatment plans differs considerably and implies a re-definition and interpretation of 'Past', 'Present' and 'Future'. Temporal conceptions and time estimations of patients and therapists may influence the access to treatment and treatment outcomes. Societal values--lack of time in affluent societies--and a general acceleration in the fields of communication, consumption, work and leisure are mirrored in the treatment system. Recovery as a long-lasting learning process stands in sharp contrast to the 'quick fix'. The question is raised whether a post-modern concept of time is gaining importance as a counter movement, promoting a more individualised and differentiated treatment response and not any longer based on assumingly objective, technical criteria such as cost-efficiency. More research is needed on group-specific time concepts in treatment programs and the acceleration hypothesis in treatment systems.

Adaptation, Psychological↗
PubMed2000

Effect of dosing time on the total intestinal transit time of non-disintegrating systems.

The total gastrointestinal transit time of nondisintegrating tablets may be affected by dosing time; available literature on this topic is inconclusive. OROS systems are nondisintegrating osmotically driven tablets that release drug over a period of time during their transit through the gastrointestinal tract and are excreted intact in the feces. Total transit times following morning administration of OROS systems pooled from various studies (n = 1,163 systems) showed a distribution with peak frequencies clustering around 24 and 48 h and following night administration (n = 80 systems) was found to cluster around 12 and 36 h. The total transit time distribution appears to be different following morning and night administration. However, on reanalyzing the data considering clock time when the tablet was collected rather than time post-administration, most of the difference between the distribution patterns disappeared. This suggested that total transit times after morning or night administration may be related to the bowel movement habits of the study population. Therefore, OROS systems total transit time were compared to the intrinsic bowel movement pattern of the general population reported in the literature and indeed a good correlation was seen between the two. The total transit time appears to be determined by two factors: the defecation frequency and the probability of its inclusion in the defecation event which is related to its location in the GI tract. A tablet is more likely to be excreted if it is further down in the GI tract. The total transit time data for OROS systems suggest that with the morning dosing the tablet is more likely to be excreted in the bowel movement the next morning. With the night time dosing the tablet may not be far enough in the colon to be excreted in the next morning bowel movement and therefore, it is more likely to be excreted the following morning.

Adolescent↗
PubMed2001

Time-series analysis of delta13C from tree rings. I. Time trends and autocorrelation.

Univariate time-series analyses were conducted on stable carbon isotope ratios obtained from tree-ring cellulose. We looked for the presence and structure of autocorrelation. Significant autocorrelation violates the statistical independence assumption and biases hypothesis tests. Its presence would indicate the existence of lagged physiological effects that persist for longer than the current year. We analyzed data from 28 trees (60-85 years old; mean = 73 years) of western white pine (Pinus monticola Dougl.), ponderosa pine (Pinus ponderosa Laws.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca) growing in northern Idaho. Material was obtained by the stem analysis method from rings laid down in the upper portion of the crown throughout each tree's life. The sampling protocol minimized variation caused by changing light regimes within each tree. Autoregressive moving average (ARMA) models were used to describe the autocorrelation structure over time. Three time series were analyzed for each tree: the stable carbon isotope ratio (delta(13)C); discrimination (delta); and the difference between ambient and internal CO(2) concentrations (c(a) - c(i)). The effect of converting from ring cellulose to whole-leaf tissue did not affect the analysis because it was almost completely removed by the detrending that precedes time-series analysis. A simple linear or quadratic model adequately described the time trend. The residuals from the trend had a constant mean and variance, thus ensuring stationarity, a requirement for autocorrelation analysis. The trend over time for c(a) - c(i) was particularly strong (R(2) = 0.29-0.84). Autoregressive moving average analyses of the residuals from these trends indicated that two-thirds of the individual tree series contained significant autocorrelation, whereas the remaining third were random (white noise) over time. We were unable to distinguish between individuals with and without significant autocorrelation beforehand. Significant ARMA models were all of low order, with either first- or second-order (i.e., lagged 1 or 2 years, respectively) models performing well. A simple autoregressive (AR(1)), model was the most common. The most useful generalization was that the same ARMA model holds for each of the three series (delta(13)C, delta, c(a) - c(i)) for an individual tree, if the time trend has been properly removed for each series. The mean series for the two pine species were described by first-order ARMA models (1-year lags), whereas the Douglas-fir mean series were described by second-order models (2-year lags) with negligible first-order effects. Apparently, the process of constructing a mean time series for a species preserves an underlying signal related to delta(13)C while canceling some of the random individual tree variation. Furthermore, the best model for the overall mean series (e.g., for a species) cannot be inferred from a consensus of the individual tree model forms, nor can its parameters be estimated reliably from the mean of the individual tree parameters. Because two-thirds of the individual tree time series contained significant autocorrelation, the normal assumption of a random structure over time is unwarranted, even after accounting for the time trend. The residuals of an appropriate ARMA model satisfy the independence assumption, and can be used to make hypothesis tests.

Carbon Isotopes↗
PubMed1997

Context-sensitive half-times and other decrement times of inhaled anesthetics.

UNLABELLED: The length of anesthetic administration influences the rate at which concentrations of anesthetics decrease after their discontinuation. This is true for both intravenous (I.V.) and inhaled anesthetics. This has been explored in detail for I.V. anesthetics using computer simulation to calculate context-sensitive half-times (the time needed for a 50% decrease in anesthetic concentration) and other decrement times (such as the times needed for 80% or 90% decreases in anesthetic concentration). However, decrement times have not been reported for inhaled anesthetics. In this report, published pharmacokinetic parameters and computer simulation were used to compare the context-sensitive half-times and the 80% and 90% decrement times of the expected central nervous system concentrations for enflurane, isoflurane, sevoflurane, and desflurane. The context-sensitive half-times for all four anesthetics are small (<5 min) and do not increase significantly with increasing duration of anesthesia. The 80% decrement times of both sevoflurane and desflurane are also small (<8 min) and do not increase significantly with duration of anesthesia. However, the 80% decrement times of isoflurane and enflurane increase significantly after approximately 60 min of anesthesia, reaching plateaus of approximately 30 and 35 min. The 90% decrement time of desflurane increased slightly from 5 min after 30 min of anesthesia to 14 min after 6 h of anesthesia. It remained significantly less than the 90% decrement times of sevoflurane, isoflurane, and enflurane, which reached values of 65 min, 86 min, and 100 min, respectively, after 6 h of anesthesia. IMPLICATIONS: The major differences in the rates at which desflurane, sevoflurane, isoflurane, and enflurane are eliminated occur in the final 20% of the elimination process.

Adipose Tissue↗
PubMed2003

Parental perception of waiting time and its influence on parental satisfaction in an urban pediatric emergency department: are parents accurate in determining waiting time?

OBJECTIVE: The objective of this study was to determine whether parental perception of waiting time in an urban pediatric emergency department (ED) is accurate and whether the actual waiting times or their perception of waiting times impact on parental satisfaction. METHODS: A prospective convenience sample study in which the on-duty emergency physicians randomly administered a questionnaire at the time of the ED visit was used. During a 3-week period from December 15, 1999, through January 7, 2000, 500 parents or legal guardians of children who visited our ED were questioned about their perceived waiting time, and the responses were compared with the actual waiting time. The parents or guardians were also asked if they were satisfied with the waiting time. RESULTS: The majority (84%) of parents overestimated waiting time in the ED (median difference, 26 min; interquartile range, 9-50 min). Parents with perceived or actual waiting times that exceeded 2 hours were significantly more likely to be dissatisfied than parents with actual or perceived waiting times that were 1 hour or less (P < 0.001). Satisfaction was not related to the age (P = 0.35), sex (P = 0.30), race/ethnicity (P = 0.90), or mode of arrival (P = 0.28). CONCLUSION: Parents tend to overestimate waiting time. Both perceived and actual waiting times that exceed 2 hours were associated with parental dissatisfaction. ED administrators may need to keep this in mind when arranging ED staffing patterns to match peak patient hours to achieve optimal parental satisfaction.

Adolescent↗
PubMed2006

Triage rapid initial assessment by doctor (TRIAD) improves waiting time and processing time of the emergency department.

AIM: To evaluate the effect of triage rapid initial assessment by doctor (TRIAD) on waiting time and processing time of an emergency department (ED) without extra staff. METHOD: A senior emergency doctor was put into triage instead of a consultation cubicle for seven shifts of 9 hours each. All the patients were assessed and necessary interventions started at the time of triage. Waiting time and processing time of various categories of patients were compared with a control group that was sampled during the week before the trial period. RESULTS: In total, there were 1310 cases in the trial period and 1355 controls. Over a quarter (27%) of the patients received triage doctor interventions. The average waiting time was reduced by 38% and the average processing time by 23%. Patients without triage intervention also had a 24% shorter waiting time because of overall improvement in efficiency. Trauma patients and patients needing radiography particularly benefited from the new system. The waiting time and processing time of category 4 and 5 patients improved significantly as a result of more efficient processing of more urgent cases. CONCLUSION: The waiting time and processing time of the ED were greatly reduced by TRIAD without extra manpower.

Emergency Service, Hospital↗
PubMed2003

Heart failure: evaluation of cardiopulmonary transit times with time-resolved MR angiography.

PURPOSE: To measure cardiopulmonary transit times in patients with heart failure by using low-dose, time-resolved magnetic resonance (MR) angiography and to determine if transit curves reflect conventional MR indexes of cardiac function. MATERIALS AND METHODS: Twenty-six patients with heart failure and left ventricular (LV) systolic dysfunction (17 men and nine women; age range, 22-78 years) and thirteen control subjects (eight men and five women; age range, 23-59 years) were examined with MR imaging. The examination consisted of rapid cine MR imaging throughout the heart, followed by contrast material-enhanced time-resolved three-dimensional MR angiography of the cardiac chambers and pulmonary vasculature. Time-intensity curves for the pulmonary artery and ascending aorta were derived from the MR angiography images. Cardiopulmonary transit times and dispersions (full widths at half maximum [FWHM]) were determined from the curves. Transit times and FWHM values for the patients with heart failure were compared with control values by using two-tailed t tests, and transit time was correlated with standard LV functional parameters calculated from the cine MR images. RESULTS: Cardiopulmonary transit times and FWHM values were significantly prolonged in the patients with heart failure compared with those in the control patients (P <.001). Transit time correlated directly with LV end-diastolic and end-systolic volumes and inversely with LV ejection fraction (R > 0.60). However, transit time did not correlate strongly with age, body surface area, heart rate, LV mass, stroke volume, cardiac output, or sphericity index. CONCLUSION: Time-resolved MR angiography allows determination of cardiopulmonary transit times that are significantly prolonged in heart failure and correlate directly with LV volumes and inversely with LV ejection fraction.

Adult↗
PubMed2004

Systems-level integration of interval timing and reaction time.

Reaction time (RT) procedures are a prominent tool for the study of information processing by humans and other animals. The interpretation of how RT changes after manipulating the appropriate experimental variables has contributed to the contemporary understanding of a variety of cognitive constructs, including attention and memory. With the use of properly designed tasks, evaluating how RT is modified in response to various neural perturbations has become common within the realms of behavioral and cognitive neuroscience. One interesting observation made during both human and animal RT experiments is that the RT to a signal often speeds-up as more time is allotted to prepare for the signal's onset-referred to as the preparatory interval (PI) effect. In the human RT literature, the PI effect has been used as evidence for time estimation playing a fundamental role in the determination of RT. On the other hand, our theoretical understanding of time estimation remains largely divorced from the RT findings in the animal cognition literature. In order to bridge these different perspectives, we provide here a review of the behavioral parallels between RT and interval-timing experiments. Moreover, both the PI effect and interval timing are shown to be jointly influenced by neuropathologies such as Parkinson's disease in humans or dopamine-depleting brain lesions in experimental animals. The primary goal of this review is to consider human and animal RT experiments within the broader context of interval timing. This is accomplished by first integrating human RT theory with scalar timing theory-the leading model of interval timing. Following this, both RT and interval timing are discussed at a brain systems level insofar as these two processes share common neural substrates. Our conclusion is that interval timing and RT processes are in fact two sides of the same coin.

Animals↗
PubMed2001

Sex differences in estimation of time intervals and in reaction time are removed by moderate but not high doses of caffeine in coffee.

Estimation of the passage of time in the seconds-to-minutes range and reaction time are strongly dependent on a hypothetical internal clock. Dopamine is the neurotransmitter most closely related to the rate of this clock. Caffeine, probably the most consumed drug in the world, leads to an augmentation of dopamine neurotransmission. In this study coffee, which reproduces the conditions under which caffeine is normally ingested, containing 3, 75, 150 or 300 mg of caffeine, was given to healthy male and female volunteers. A computerized time estimation and reaction time test was carried out 50 min after ingestion. Sex differences in placebo control subjects (who took decaffeinated coffee with 3 mg of caffeine), with females making more accurate estimates of time intervals than males and males showing shorter reaction times than females, were removed in subject taking doses of 75 and 150 mg of caffeine in the case of time estimation and 150 mg in the case of reaction time. The 300 mg dose induced overestimation of time in females and shortened the reaction time in males. There were no sex differences in the pharmacokinetics of caffeine, as measured in salivary concentration of caffeine using high-performance liquid chromatography. Results indicating sex differences in time estimation or reaction time should not be generalized from the laboratory to real life without considering the fact that everyday coffee consumption may eliminate these differences. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2004

Waiting time information services: an evaluation of how well clearance time statistics can forecast a patient's wait.

Governments in some countries have created web-based information services so that patients requiring elective surgery can compare the waiting times of surgical units. This study investigated how accurately the waiting times of patients about to join a waiting list can be forecast by various clearance time statistics. It used 3 years of elective surgical activity data that covered 46 surgeons in 10 specialties within a public hospital. Six clearance time functions were tested, and the best function was compared with average waiting time statistics derived from census and throughput data. The forecast accuracy of the clearance time functions was found to be greatly affected by the characteristics and behaviour of a surgeon's waiting list. Although there was less difference in performance among the six functions, systematic differences between them were also found. The best of these performed better than the statistics derived from waiting time data, especially where waiting times exceeded 6 months. Yet, its accuracy was still poor. For each surgeon with an average waiting time of more than 6 months, at least 20% of patients waited more than 90 days beyond the clearance time forecast. Consequently, while waiting time information services should consider adopting the clearance time approach, they need to be explicit about its statistical limitations.

Elective Surgical Procedures↗
PubMed1999

Time course of individual Ca2+ sparks in frog skeletal muscle recorded at high time resolution.

Discrete Ca2+ release events (Ca2+ "sparks") were recorded in cut segments of single frog skeletal muscle fibers using a video-rate laser-scanning confocal microscope operating in line-scan mode (63 microseconds per line). Fibers loaded with the Ca2+ indicator fluo-3 were voltage clamped at a holding potential of 0 mV, briefly reprimed at -90 mV, and then strongly depolarized with a large test pulse to activate any reprimed voltage sensors. Using this high time resolution system, it was possible to record individual Ca2+ sparks at approximately 30-fold higher time resolution than previously attained. The resulting new experimental data provides a means of characterizing the time course of fluorescence during the brief (a few milliseconds) rising phase of a spark, which was not possible with the previously used 1.5-2 ms per line confocal systems. Analysis of the time course of individual identified events indicates that fluorescence begins to rise rather abruptly at the start of the spark, continues to rise at a slightly decreasing rate to a relatively sharp peak, and then declines along a quasi-exponential time course. The mean rise time of 198 sparks was 4.7 +/- 0.1 ms, and there was no correlation between rise time and peak amplitude. Average sparks constructed by temporally and spatially superimposing and summing groups of individual sparks having similar rise times gave a lower noise representation of the sparks, consistent with the time course of individual events. In theory, the rising phase of a spark provides a lower bound estimation of the time that Ca2+ ions are being released by the sarcoplasmic reticulum Ca2+ channel(s) generating the spark. The observed time course of fluorescence suggests that the Ca2+ release underlying a spark could continue at a fairly constant rate throughout the rising phase of the spark, and then stop rather abruptly at the time of the peak.

Algorithms↗