Significant Phase Effect Research Articles

Effects of whale-watching activities on southern right whales in Encounter Bay, South Australia

Southern right whales (Eubalaena australis) are listed as Endangered under the Australian EPBC Act 1999. They migrate to shallow, coastal waters during the winter to mate, calve and nurse their young. During this time, they are easily accessible to the boat-based whale-watching industry. The aim of the study was to determine if whale-watching at 300 m distance affects the behaviour of southern right whales. To achieve this, behavioural focal follows on mother-calf pairs were conducted using unmanned aerial vehicles (UAVs) in the presence and absence of a commercial whale-watching vessel. There was no significant effect of phase (control, before, during, after) on the whales’ respiration rate, swim speed, nursing rate and duration, maternal rate of active behaviours, tactile contact or calf pectoral fin contact. There was a significant reduction in resting between control and after phases, for both mothers (from 62% to 30%) and calves (from 16% to 1%). At 300 m distance and slow speed, vessel noise was measured to be slightly above ambient noise at the lower TOL0.25 kHz band, however, vessel noise was masked by ambient noise within the higher frequency TOL2–10 kHz bands. A factor which may have contributed to a decline in resting after whale-watch approaches, was an increase in vessel speed upon departure, which consequently increased vessel noise. Based on this, we recommend that vessels maintain a slow speed (e.g., ≤10 knots) within 1 km distance from the whales whilst conducting whale-watch activities.

Effects of Oral Leak Size on Valsalva Responses.

IntroductionWe hypothesized that oral leak size, a hitherto unstudied technical variable, would influence hemodynamic responses and difficulty level in executing the Valsalva maneuver (VM).MethodsBased on power analysis, 38 healthy participants were included. Oral leak size in random order was 0.35, 0.71, 1.01,1.40 mm. Level of difficulty was rated 1 to 10, with ≥7–10 being severe. VM was performed at 40 mmHg expiratory strain for 15 s. Three trials were averaged for each leak size. Data were analyzed by repeated measures ANOVA and pairwise comparisons with Tukey adjustment, a mixed effect model, and a generalized linear model.ResultsOf the 38 participants, 4 were excluded from analysis for protocol deviation. Phase II L mean BP (MBP) was significantly higher with the largest leak versus all others (P < 0.001). TL was significantly lower with the largest leak versus all others (P = 0.0029). Difficulty performing the VM increased significantly with every increase in leak size (P < 0.001), and a significantly higher percentage of participants reported severe difficulty with leak 4 compared with leak 1 (P < 0.001), 2 (P = 0.0068), and 3 (P = 0.0068). There was no significant effect of phase II E SBP decline on phase II L MBP increase (P = 0.0752). Difficulty increased significantly with one unit increase in phase II L MBP (P = 0.0002).ConclusionsOral leak size affected VM hemodynamic parameters and level of difficulty. Oral leak size exceeding 1.01 mm significantly affected phase II L MBP. Level of difficulty rose with increasing leak size and was significantly correlated with increase in phase II L MBP.

0118 Performance on a Computerized Threat Elimination Task in an Animated Environment during Total Sleep Deprivation

Abstract Introduction Military and law enforcement operators must make split-second decisions on whether to shoot during confrontations. Quick responses are crucial when force is necessary, but accurate decision-making is also imperative. Often, decisions are made while fatigued, which could impair speed and/or accuracy. Furthermore, the reliability of background information may impact performance. We investigated performance on a computerized shooting task during a total sleep deprivation (TSD) study. Methods N=86 healthy adults (39 males, age 21-38) completed a 4-day/3-night in-laboratory study, randomly assigned to a TSD (n=56) or control (n=28) condition. A custom task was administered after 32h or 8h of wakefulness (TSD and control groups). Participants were to shoot enemy robots (press spacebar) and not shoot friendly robots (no response) within 500ms of each robot being revealed inside shipping crates (1-5s inter-trial-interval). The task introduction described which crates would contain enemies, but the intel’s accuracy varied across four phases: 100% (20 trials), 80% (120 trials), and 20% (40 trials), then irrelevant in a new environment (60 trials). Reaction time (RT) and accuracy (hits and false alarms (FAs)) were analyzed using 2x4 mixed-effects ANOVAs to determine the effects of condition, phase, and their interaction. Results There was a significant effect of phase on RT (p&amp;lt;0.001); in both conditions, participants reacted faster in phase 1 than all other phases. However, there was no effect of condition (p=0.20) or phase-condition interaction (p=0.080) on RT. There were significant effects of condition on hits (p&amp;lt;0.001) and FAs (p=0.004); TSD had fewer hits and more FAs than the control group. There was an effect of phase on hits (p=0.045), with fewer hits in phase 1, and a condition-phase interaction (p=0.026) showing that the TSD group experienced less improvement in hits. For FAs, there was no effect of phase (p=0.86) or phase-condition interaction (p=0.86). Conclusion The results suggest a speed/accuracy tradeoff during TSD, where relative to the control group, RTs remained equivalent, but accuracy was worse. In both groups, the RT slowing from phase 1 to subsequent phases, suggests that participants initially used the intel to facilitate quicker decision-making, but disregarded it once it was not completely reliable. Support (If Any) CDMRP grants W81XWH-16-1-0319 and W81XWH-20-1-0442

Quasi-experimental N = 1 evaluation of the effectiveness of cognitive analytic therapy for dependent personality disorder.

The evidence base for the treatment of dependent personality disorder (DPD) is sparse and there are few credible evaluations of the effectiveness of integrative psychotherapies. This study therefore employed an A/B with extended follow-up quasi-Experimental single case design with a female patient meeting diagnostic criteria for DPD, treated with cognitive analytic therapy (CAT). The patient was treated with the 24-session version of the model, with 6 months structured follow-up. Fidelity to the treatment model was found to be satisfactory. There was a significant effect of phase of study in the time series of the primary idiographic measure of reassurance-seeking. On the primary nomothetic measure (i.e., the Interpersonal Dependency Inventory), there was a reliable improvement to self-confidence on assessment-termination comparisons. Confidence in the reliability of the idiographic results is limited by evidence of improvements occurring during the baseline phase. The methodological limitations and clinical/theoretical implications are discussed for the use of integrative psychotherapies with patients with strong dependent traits.

Hypoattenuation on CTA images with large vessel occlusion: timing affects conspicuity.

Parenchymal hypoattenuation distal to occlusions on CTA source images (CTASI) is perceived because of the differences in tissue contrast compared to normally perfused tissue. This difference in conspicuity can be measured objectively. We evaluated the effect of contrast timing on the conspicuity of ischemic areas. We collected consecutive patients, retrospectively, between 2012 and 2014 with large vessel occlusions that had dynamic multiphase CT angiography (CTA) and CT perfusion (CTP). We identified areas of low cerebral blood volume on CTP maps and drew the region of interest (ROI) on the corresponding CTASI. A second ROI was placed in an area of normally perfused tissue. We evaluated conspicuity by comparing the absolute and relative change in attenuation between ischemic and normally perfused tissue over seven time points. The median absolute and relative conspicuity was greatest at the peak arterial (8.6 HU (IQR 5.1-13.9); 1.15 (1.09-1.26)), notch (9.4 HU (5.8-14.9); 1.17 (1.10-1.27)), and peak venous phases (7.0 HU (3.1-12.7); 1.13 (1.05-1.23)) compared to other portions of the time-attenuation curve (TAC). There was a significant effect of phase on the TAC for the conspicuity of ischemic vs normally perfused areas (P<0.00001). The conspicuity of ischemic areas distal to a large artery occlusion in acute stroke is dependent on the phase of contrast arrival with dynamic CTASI and is objectively greatest in the mid-phase of the TAC.

Effect of Alternate Nostril Breathing Exercise on Experimentally Induced Anxiety in Healthy Volunteers Using the Simulated Public Speaking Model: A Randomized Controlled Pilot Study.

A randomized controlled pilot study was carried out to determine the effect of a 15-minute practice of ANB exercise on experimentally induced anxiety using the simulated public speaking model in yoga-naïve healthy young adults. Thirty consenting medical students were equally divided into test and control groups. The test group performed alternate nostril breathing exercise for 15 minutes, while the control group sat in a quiet room before participating in the simulated public speaking test (SPST). Visual Analog Mood Scale and Self-Statements during Public Speaking scale were used to measure the mood state at different phases of the SPST. The psychometric scores of both groups were comparable at baseline. Repeated-measures ANOVA showed a significant effect of phase (p < 0.05), but group and gender did not have statistically significant influence on the mean anxiety scores. However, the test group showed a trend towards lower mean scores for the anxiety factor when compared with the control group. Considering the limitations of this pilot study and the trend seen towards lower anxiety in the test group, alternate nostril breathing may have potential anxiolytic effect in acute stressful situations. A study with larger sample size is therefore warranted. This trial is registered with CTRI/2014/03/004460.

On the Use of Geophones in the Low-Frequency Regime to Study Rail Vibrations

AimFor a long time, our research team has been successfully using 2Hz geophones to measure vertical velocities and displacements of rails vibrating as a consequence of high-speed train traffic (200 – 300km/h). Our aim is to extend the use of geophones to study vertical vibrations of rails also for lower traffic velocities (as low as possible). The lower the train velocity, the more important the low frequencies to describe the rail vibration. Given that below twice the resonant frequency of the geophone (ωn) the rate |output|/|input| differs significantly from 1, the amplitude of the signal in this frequency interval (0 – 2ωn) must be restored in order to obtain reliable measurements. In this contribution we present a method to correct the amplitude of geophone data in the low-frequency regime, as well as the analysis of “in situ” measurements for testing the goodness of the method. MethodDespite the one-to-one relationship between the spectral amplitude of the input signal and the output of a geophone for frequencies above 2ωn, there are significant phase effects up to 10ωn. This is the reason why phase correction must always be applied. We take advantage of the Discrete Fourier Transform (DFT) to convert the signals from the time domain into the frequency domain. Thus we are able to restore not only the phase but also the amplitude by applying the inverse transfer function of the geophone. The restored data are converted into the time domain by using the inverse DFT. We compare the vertical rail displacements obtained by integrating the amplitude- and phase-corrected velocity measurements with those calculated when only the phase-correction is applied for a rail vibrating when a train travels at 5, 50, 100, 130 and 160km/h. ResultsPreviously to this work, we were able to measure vertical velocities and displacements in rails vibrating as a consequence of high-speed train traffic by using 2Hz geophones. Now, with the new-implemented amplitude correction in the frequency domain, we are also able to obtain these quantities for rails that vibrate when trains with velocity as low as 50km/h travel over them, allowing us to perform studies in underground rapid transit systems.

Acetone as biomarker for ketosis buildup capability--a study in healthy individuals under combined high fat and starvation diets.

BackgroundKetogenic diets are high fat and low carbohydrate or very low carbohydrate diets, which render high production of ketones upon consumption known as nutritional ketosis (NK). Ketosis is also produced during fasting periods, which is known as fasting ketosis (FK). Recently, the combinations of NK and FK, as well as NK alone, have been used as resources for weight loss management and treatment of epilepsy.MethodsA crossover study design was applied to 11 healthy individuals, who maintained moderately sedentary lifestyle, and consumed three types of diet randomly assigned over a three-week period. All participants completed the diets in a randomized and counterbalanced fashion. Each weekly diet protocol included three phases: Phase 1 - A mixed diet with ratio of fat: (carbohydrate + protein) by mass of 0.18 or the equivalence of 29% energy from fat from Day 1 to Day 5. Phase 2- A mixed or a high-fat diet with ratio of fat: (carbohydrate + protein) by mass of approximately 0.18, 1.63, or 3.80 on Day 6 or the equivalence of 29%, 79%, or 90% energy from fat, respectively. Phase 3 - A fasting diet with no calorie intake on Day 7. Caloric intake from diets on Day 1 to Day 6 was equal to each individual’s energy expenditure. On Day 7, ketone buildup from FK was measured.ResultsA statistically significant effect of Phase 2 (Day 6) diet was found on FK of Day 7, as indicated by repeated analysis of variance (ANOVA), F(2,20) = 6.73, p < 0.0058. Using a Fisher LDS pair-wise comparison, higher significant levels of acetone buildup were found for diets with 79% fat content and 90% fat content vs. 29% fat content (with p = 0.00159**, and 0.04435**, respectively), with no significant difference between diets with 79% fat content and 90% fat content. In addition, independent of the diet, a significantly higher ketone buildup capability of subjects with higher resting energy expenditure (R2 = 0.92), and lower body mass index (R2 = 0.71) was observed during FK.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-015-0028-x) contains supplementary material, which is available to authorized users.

Prokaryotic successions and diversity in composts as revealed by 454-pyrosequencing

In this study, 454-pyrosequencing was applied to analyze prokaryotic patterns in three lignocellulosic composting systems across the three main phases. In all composts, diversity expanded as composting progressed. Communities in the mesophilic- and mature-phases of all composts were distinct, which did not support the concept that organisms present in the mesophilic phase enter dormancy during thermophilic period, and re-colonize the compost at the mature phase. Analysis of similarity revealed compost phase was a significant source of dissimilarity (p=0.011), compost type was not (p=0.401). Analysis of variance also showed significant phase effects on the abundance of (p-value): Archaea (0.001), Planctomycetes (0.002), Chloroflexi (0.016), Deltaproteobacteria (0.027), Bacteria (0.046) and Gammaproteobacteria (0.056). Mature-phase compost was a preferred niche for the Archaea, Planctomycetes, Chloroflexi and Deltaproteobacteria, while Gammaproteobacteria were predominant in earlier phases. Thus, the mature phase pattern could have implications in the development of biomarker assays for compost maturity.

Association of menstrual cycle phase with the core components of empathy

Evidence has accumulated that emotion recognition performance varies with menstrual cycle phase. However, according to some empathy models, facial affect recognition constitutes only one component of empathic behavior, besides emotional perspective taking and affective responsiveness. It remains unclear whether menstrual cycle phase and thus estradiol and progesterone levels are also associated with the two other empathy constructs.Therefore, we investigated 40 healthy right-handed females, 20 during their follicular phase and 20 during their midluteal phase and compared their performance in three tasks tapping the empathic components as well as self-report data. Salivary hormone levels were obtained and correlated with performance parameters. Subjects were matched for age and education and did not differ in neuropsychological function. Analysis of empathy performance revealed a significant effect of phase in emotion recognition, showing higher accuracy in the follicular group. Regarding affective responsiveness, we observed a significant difference in reaction times, with faster responses for sad and angry stimuli in the midluteal group. No significant group difference emerged for emotional perspective taking. Furthermore, significant correlations between progesterone levels and emotion recognition accuracy and affective responsiveness emerged only in the luteal group. However, groups did not differ in self-reported empathy.Our results indicate that menstrual cycle phase and thus ovarian hormone concentration are differentially related to empathic behavior, particularly emotion recognition and responsiveness to negative situations, with progesterone covarying with both in the luteal phase.

Oral Contraceptive Use May Attenuate Menstrual Cycle-Induced Ventilatory Changes in Endurance Trained Runners

The relationship between two menstrual cycle phases and cardio respiratory fitness in athletes on oral contraceptives and not on oral contraceptives was assessed in a pilot study. Twelve endurance-trained college cross country runners underwent maximal oxygen consumption treadmill testing, during the late follicular/ovulatory phase and late luteal/premenstrual phase of their menstrual cycle. No significant differences were detected in maximal oxygen consumption between the oral contraceptive group and non-oral contraceptive group or between the two phases. There was a non-significant phase effect in the non-oral contraceptive group with maximal ventilation averaging 90.5±14.6 L/min during the late follicular/ovulatory phase and decreasing to 79.1±9.8 L/min during the late luteal/premenstrual phase (p=0.102). Maximal ventilation was significantly lower by 15.6% between oral contraceptive and non-oral contraceptive users during the late luteal/premenstrual phase (93.7+7.2 L/min vs 79.1+9.8 L/min, p=0.014, respectively). There was no significant phase effect in the oral contraceptive group for maximal ventilation. While oral contraceptive use was associated with an attenuation of the negative effect of the late luteal/premenstrual phase on ventilator performance, there was no effect on maximal oxygen consumption.

GnRH-agonist induced depressive and anxiety symptoms during in vitro fertilization–embryo transfer cycles

To determine whether the use of a GnRH agonist inducing a hypogonadic state during IVF-ET cycles induces negative mood symptoms, we conducted a prospective randomized study in 108 women comparing two different controlled ovarian stimulation protocols. A significant phase effect was observed for depression and anxiety symptoms during IVF-ET cycles reflecting an increase in symptoms between the hypogonadal phase and the peak in gonadotropin stimulation; however, the hypogonadal phase induced by the GnRH agonist was not associated with a significant increase in any of the studied mood parameters.

Ergonomic Safety of Surgical Techniques and Standing Positions Associated with Laparoscopic Cholecystectomy

Laparoscopic cholecystectomy (LC), a procedure in which, using either a one-handed or two-handed technique, a surgeon removes a symptomatic gallbladder in a minimally invasive manner, is commonly—due to its relatively high safety level—the initial procedure that a resident will perform. Investigation of the ergonomics associated with LC one-handed and two-handed techniques is one goal of this study. Identification of which of two standing positions (between legs or at side) used during LC is the more ergonomically favorable is the other. Knowledge gained from our research in these issues is intended to be applicable both to surgical training and the operating room environment. Eight right-handed laparoscopic surgeons with varying levels of surgical skills were recruited for this study. Each performed LC a total of four times on a virtual reality (VR) simulator with each performance incorporating one of the following conditions: either the one-handed or two-handed surgical technique or the position of standing between the patient's legs or at the patient's side. Each trial was also divided into two phases: 1) dissection and clipping and 2) gall bladder removal. During the performance of LC, physical ergonomic data were collected though surface electrode electromyography (EMG) and two force plates. Additionally NASA-Task Load Index (TLX) and secondary time estimation were used for cognitive ergonomic assessment. Standing at the side produced a significantly higher weight-loading ratio (WLR) than standing between the legs. Comparison between techniques indicated that the two-handed technique caused higher WLR. Significant phase effect equated increased WLR with phase 2 gall bladder removal. No statistical interactions among technique, standing position, and phase were significant. Analysis of NASA-TLX showed that global workload, influenced mainly by significant physical workload and effort scales, was higher with the side-standing position and the two-handed technique. The results from time estimation analysis, although statistically marginal, demonstrated that the one-handed technique is more mentally demanding. Our study demonstrated that due to lower physical as well as mental workload, the two-handed technique performed with the surgeon positioned between the patient's legs is the most ergonomically favorable combination. Additionally, it was demonstrated that the pedal for cautery operation requires ergonomic improvement. These specific findings encourage us to continue research into what proof ergonomics can provide regarding what constitutes the most efficacious approaches to surgical procedures and to optimizing patient safety and the surgical environment.

Ergonomic Safety of Surgical Techniques and Standing Positions Associated with Laparoscopic Cholecystectomy

Laparoscopic cholecystectomy (LC), a procedure in which, using either a one-handed or two-handed technique, a surgeon removes a symptomatic gallbladder in a minimally invasive manner, is commonly—due to its relatively high safety level—the initial procedure that a resident will perform. Investigation of the ergonomics associated with LC one-handed and two-handed techniques is one goal of this study. Identification of which of two standing positions (between legs or at side) used during LC is the more ergonomically favorable is the other. Knowledge gained from our research in these issues is intended to be applicable both to surgical training and the operating room environment. Eight right-handed laparoscopic surgeons with varying levels of surgical skills were recruited for this study. Each performed LC a total of four times on a virtual reality (VR) simulator with each performance incorporating one of the following conditions: either the one-handed or two-handed surgical technique or the position of standing between the patient's legs or at the patient's side. Each trial was also divided into two phases: 1) dissection and clipping and 2) gall bladder removal. During the performance of LC, physical ergonomic data were collected though surface electrode electromyography (EMG) and two force plates. Additionally NASA-Task Load Index (TLX) and secondary time estimation were used for cognitive ergonomic assessment. Standing at the side produced a significantly higher weight-loading ratio (WLR) than standing between the legs. Comparison between techniques indicated that the two-handed technique caused higher WLR. Significant phase effect equated increased WLR with phase 2 gall bladder removal. No statistical interactions among technique, standing position, and phase were significant. Analysis of NASA-TLX showed that global workload, influenced mainly by significant physical workload and effort scales, was higher with the side-standing position and the two-handed technique. The results from time estimation analysis, although statistically marginal, demonstrated that the one-handed technique is more mentally demanding. Our study demonstrated that due to lower physical as well as mental workload, the two-handed technique performed with the surgeon positioned between the patient's legs is the most ergonomically favorable combination. Additionally, it was demonstrated that the pedal for cautery operation requires ergonomic improvement. These specific findings encourage us to continue research into what proof ergonomics can provide regarding what constitutes the most efficacious approaches to surgical procedures and to optimizing patient safety and the surgical environment.

Measurement of body segment parameters using dual energy X-ray absorptiometry and three-dimensional geometry: An application in gait analysis

Body segment parameters (BSP) are essential input for the computations in kinetics of motion applied in the field of biomechanics. These data are usually obtained from population-specific predictive equations which present limitations in being representative of the population under study. More recently, medical imaging techniques have been adopted but are limited to two-dimensional (2-D) measurements or required extensive tomographic images for three-dimensional (3-D) reconstruction. We proposed an in vivo method to measure 3-D BSP using X-ray imaging and 3-D exterior geometry. Criterion values of the BSP were determined using magnetic resonance imaging (MRI) which has previously been validated. Errors for all BSP values were less than 2% when values derived from our method were compared to the criterion values. We found no significant difference between our method and four selected BSP models in both stance and swing phase. Significant phase effects were observed for our method and other BSP models between stance and swing phase. Significant differences ( p<0.05) between root mean square error (RMSE) ranged from 0.0177 to 0.0234 and 0.0234 to 0.097 Nm kg −1 for the knee and hip joints, respectively. However, these BSP variations brought about effects on moment output that were less than 0.09 Nm kg −1. Our findings suggest joint kinetic computations during normal gait are relatively insensitive to BSP variations. However, the influence of BSP cannot be undermined in movements that generate higher acceleration at the limbs. Considering the accuracy of our method, it could be used as a novel in vivo method to obtain direct 3-D BSP measurements.

Different Dynamics of Performance and Brain Activation in the Time Course of Perceptual Learning

Perceptual learning is regarded as a manifestation of experience-dependent plasticity in the sensory systems, yet the underlying neural mechanisms remain unclear. We measured the dynamics of performance on a visual task and brain activation in the human primary visual cortex (V1) across the time course of perceptual learning. Within the first few weeks of training, brain activation in a V1 subregion corresponding to the trained visual field quadrant and task performance both increased. However, while performance levels then saturated and were maintained at a constant level, brain activation in the corresponding areas decreased to the level observed before training. These findings indicate that there are distinct temporal phases in the time course of perceptual learning, related to differential dynamics of BOLD activity in visual cortex.

Search for short-time phase effects in the electronic damage evolution – A case study with silicon

This work focusses on the production and decay properties of inner-shell vacancies and valence-band excitations induced by swift highly charged ions interacting with amorphous and crystalline Si. High resolution electron spectra have been taken for fast heavy ions at 1.78–5MeV/u as well as for electrons of similar velocity incident on atomically clean Si targets of well defined phase. Various Auger-electron structures are analyzed concerning their width, their intensity and exact peak position. All measured peaks show a small shift towards lower energy when the charge of the projectile is increased. This finding is an indication for a nuclear-track potential inside the ion track. A detailed analysis of the Auger-electron spectra for amorphous Si and crystalline Si(111) 7×7 points to a small but significant phase effect in the short-time dynamics of ion tracks.

Emotion recognition accuracy in healthy young females is associated with cycle phase

Several studies reported a significant influence of ovarian hormone status on cognition and person perception. In particular, it has been stated that female mating preferences are shifted during the menstrual cycle. It remains, however, unclear if facial emotion recognition, a prerequisite for successful social interaction, is also influenced by estradiol and progesterone levels. Hence, we investigated 32 healthy right-handed females, 15 during their follicular phase and 17 during their luteal phase and compared their recognition accuracy. Hormone levels were correlated with several neuropsychological parameters. Subjects were matched for age and education and did not differ in any neuropsychological function. Analysis of emotion recognition performance (ANOVA) revealed a significant effect of phase, showing higher accuracy in the follicular group. Furthermore, a significant negative correlation between progesterone level and emotion recognition performance emerged, indicating higher accuracy with lower progesterone levels, hence supporting the group differences. Our results indicate a significant association of menstrual cycle phase and thus ovarian hormone concentration on facial emotion recognition, with progesterone exerting a special influence on this social–emotional ability.

Determining behavioural and physiological responses to pain in infants at risk for neurological impairment

Multiple researchers have validated indicators and measures of infant pain. However, infants at risk for neurologic impairment (NI) have been under studied. Therefore, whether their pain responses are similar to those of other infants is unknown. Pain responses to heel lance from 149 neonates (GA > 25–40 weeks) from 3 Canadian Neonatal Intensive Care units at high (Cohort A, n = 54), moderate (Cohort B, n = 45) and low (Cohort C, n = 50) risk for NI were compared in a prospective observational cohort study. A significant Cohort by Phase interaction for total facial action ( F (6, 409) = 3.50, p = 0.0022) and 4 individual facial actions existed; with Cohort C demonstrating the most facial action. A significant Phase effect existed for increased maximum Heart Rate ( F (3, 431) = 58.1, p = 0.001), minimum Heart Rate ( F (3, 431) = 78.7, p = 0.001), maximum Oxygen saturation ( F (3, 425) = 47.6, p = 0.001), and minimum oxygen saturation ( F (3, 425) = 12.2, p = 0.001) with no Cohort differences. Cohort B had significantly higher minimum ( F (2, 79) = 3.71, p = 0.029), and mean ( F (2, 79) = 4.04, p = 0.021) fundamental cry frequencies. A significant Phase effect for low/high frequency Heart Rate Variability (HRV) ratio ( F (2, 216) = 4.97, p = 0.008) was found with the greatest decrease in Cohort A. Significant Cohort by Phase interactions existed for low and high frequency HRV. All infants responded to the most painful phase of the heel lance; however, infants at moderate and highest risk for NI exhibited decreased responses in some indicators.

Effect of circadian phase on performance of rats in the Morris water maze task.

The authors examined spatial working memory in the Morris water maze during the activity and rest periods of Wistar rats. Wheel-running activity was measured continuously as a marker of circadian phase. To minimize possible masking effects on performance, animals were placed in constant dim light the day before testing and tested in similar light conditions. Three experiments were run, each of them using animals varying in their previous experience in the water maze. Half of the animals of each experiment were tested 2 to 3 h after activity onset (active group), and the other half were tested 14 to 15 h after activity onset (inactive group). In the three experiments, a significant phase effect was observed in the animals' performance in the water maze; animals tested in the active phase showed steeper acquisition curves. These phase effects on performance are due to the animals' search pattern and not to a better acquisition and maintenance of spatial information; rats tested in the inactive phase found the platform faster on the first trial of the test, when the information on the location of the platform had not been presented to the animals. This effect vanished as the amount of training in the pool increased. Finally, swimming speed also showed a temporal effect, suggesting the existence of a phase effect for motivation to escape from the water; rats tested during their inactive phase tended to swim faster. All together, the data suggest a modulating effect of the biological clock on performance in the water maze, particularly when the animals are less experienced.