Effect of transmembrane pressure control on energy efficiency during skim milk concentration by ultrafiltration at 10 and 50°C.

The efficiency of the ultrafiltration process during skim milk concentration was studied using both dynamic and constant (465 or 672kPa) transmembrane pressure experiments at refrigerated temperature (10°C) and high temperature (50°C). The pilot-scale module was equipped with a 10-kDa polyethersulfone spiral-wound membrane element with a surface area of 2.04m2. Permeation flux, resistance-in-series model, mineral and protein rejection, and energy consumption were studied as a function of temperature and transmembrane pressure applied. Higher permeation flux values were systematically obtained at 50°C. Also, a significant temperature effect was found for calcium rejection, which was lower at 10°C compared with 50°C. Total hydraulic resistance and reversible fouling resistance were higher at 50°C than at 10°C. No change in protein rejection was observed, depending on the operating mode studied. Permeation flux, which was higher at 50°C, had lower pumping energy consumption compared with ultrafiltration at the colder temperature. Also, the low ultrafiltration temperature required a higher total energy consumption to reach the 3.6× retentate compared with ultrafiltration at 50°C. Overall, our study shows that the operating parameters and temperature can be optimized using an energy efficiency ratio.

Heart rate variability response to standing in men and women receiving d,l-sotalol following coronary artery bypass graft surgery.

Heart rate variability (HRV), a quantitative marker of autonomic control of heart rate (HR), declines in men and women following coronary artery bypass graft (CABG) surgery. Although d,l-sotalol is prescribed following CABG surgery primarily for its antiarrhythmic effect, its effects on HRV have not been reported; the ß-adrenergic antagonist effect of d,l-sotalol may attenuate sympathetically mediated HR and blood pressure (BP) responses to standing, resulting in postural hypotension. In this study, the HRV response to standing 4 days following CABG surgery in men and women prescribed d,l-sotalol was measured to examine the influence of d,l-sotalol on previously reported HRV responses, taking age and gender into consideration. Participants included 28 men and 10 women who completed testing in supine and standing postures; all had received low-dose d,l-sotalol daily since the first postoperative day. Data included continuous electrocardiograph recording of R-R interval for 10 min in each posture. Participants showed significant effects of standing on the autonomic modulation of HR, as seen by a decrease in parasympathetic indices and R-R interval and an increase in BP. In men, standing decreased parasympathetic modulation and increased the sympathetic nervous system indicator, but previously reported age effects were not seen. In women, standing decreased low frequency power and R-R interval and increased BP, with older women having a smaller increase in BP, suggesting an attenuated response. The differential autonomic nervous system modulation of HR as a function of gender and age after CABG surgery may be attenuated by d,l-sotalol.

Fetal sensitivity to properties of maternal speech and language.

Fetal speech and language abilities were examined in 104 low-risk fetuses at 33-41 weeks gestational age using a familiarization/novelty paradigm. Fetuses were familiarized with a tape recording of either their mother or a female stranger reading the same passage and subsequently presented with a novel speaker or language: Studies (1) & (2) the alternate voice, (3) the father's voice, and (4) a female stranger speaking in native English or a foreign language (Mandarin); heart rate was recorded continuously. Data analyses revealed a novelty response to the mother's voice and a novel foreign language. An offset response was observed following termination of the father's and a female stranger's voice. These findings provide evidence of fetal attention, memory, and learning of voices and language, indicating that newborn speech/language abilities have their origins before birth. They suggest that neural networks sensitive to properties of the mother's voice and native-language speech are being formed.

Fetal behavior in smoking compared to non-smoking pregnant women.

OBJECTIVE: To determine the effects of maternal smoking on fetal spontaneous behavior and auditory processing. METHODS: 38 fetuses of smoking (n=18) and non-smoking (n=20) mothers, stratified by gestational age (<37, >or=37 weeks GA), were examined at least 1h following smoking. Observations included spontaneous fetal heart rate (FHR; 20 min) and body movements (20 min) followed by a 2 min audiotape of the mother reading a story while FHR and body movements were recorded. RESULTS: There were no differences in spontaneous behaviors; full-term fetuses showed a FHR acceleration and body movement during the mother's voice. A FHR response following voice offset was limited to fetuses less than 37 weeks GA of non-smoking mothers. CONCLUSION: Fetuses less than 37 weeks GA of mothers who smoke throughout pregnancy have a delayed onset of response to the maternal voice, a subtle difference which may have implications for later language development for prematurely born infants which needs further investigation.

Fetal development: voice processing in normotensive and hypertensive pregnancies.

Recent observation of maternal voice recognition provides evidence of rudimentary memory and learning in healthy term fetuses. However, such higher order auditory processing has not been examined in the presence of maternal hypertension, which is associated with reduced and/or impaired uteroplacental blood flow. In this study, voice processing was examined in 40 fetuses (gestational ages of 33 to 41 weeks) of hypertensive and normotensive women. Fetuses received 2 min of no sound, 2 min of a tape-recorded story read by their mothers or by a female stranger, and 2 min of no sound while fetal heart rate was recorded. Results demonstrated that fetuses in the normotensive group had heart rate accelerations during the playing of their mother's voice, whereas the response occurred in the hypertensive group following maternal voice offset. Across all fetuses, a greater fetal heart rate change was observed when the amniotic fluid index was above compared to below the median (i.e., 150 mm), indicating that amniotic fluid volume may be an independent moderator of fetal auditory sensitivity. It was concluded that differential fetal responding to the mother's voice in pregnancies complicated by maternal hypertension may reflect functional elevation of sensorineural threshold or a delay in auditory system maturation, signifying functional differences during fetal life or subtle differences in the development of the central nervous system.

Maternal cardiac autonomic function and fetal heart rate in preeclamptic compared to normotensive pregnancies.

BACKGROUND: Preeclampsia during pregnancy increases a woman's risk of cardiovascular disease in two ways. Women who develop preeclampsia are at increased risk for the development of hypertension and cardiovascular disease later in life. As well, fetal adaptations (e.g., growth restriction) may lead to the development of cardiovascular risk factors (e.g., obesity, increased cholesterol) in the offspring. Although atypical maternal cardiac autonomic function has been reported in preeclampsia, to date, its effects on fetal cardiac function have not been determined. PURPOSE: To characterize the pattern of short-term maternal cardiac autonomic modulation and spontaneous fetal heart rate changes in preeclamptic compared to normotensive women and to determine the relationship between them. METHOD: Twenty-seven mother-fetal pairs (n = 9 preeclamptic, n = 18 normotensive) at 32 to 40 weeks gestation were tested on one occasion. Maternal autonomic modulation of heart rate was measured for 20 minutes using electrocardiographic and beat-by-beat arterial systolic blood pressure recordings. Simultaneously, spontaneous fetal heart rate was obtained using a cardiotachograph. Women's cardiac autonomic responses to orthostatic stress were obtained for five minutes in a standing position. RESULTS: Comparisons of maternal cardiac measures in the preeclamptic versus the normotensive group showed that the preeclamptic group had a decreased parasympathetic nervous system indicator and an increased sympathetic nervous system indicator with increasing gestation. In response to orthostatic stress, women in both groups showed a similar increase in arterial systolic blood pressure and a decrease in parasympathetic nervous system indicator and R-R interval when standing compared to lying. Fetuses in the normotensive compared to the preeclamptic group had more spontaneous fetal heart rate accelerations; the greater the decrease in the parasympathetic nervous system indicator from lying to standing, the greater the number of fetal heart rate accelerations. CONCLUSIONS: These findings serve to further our understanding of the cardiovascular pathophysiology of preeclampsia in both the mother and the fetus. Women who develop preeclampsia during pregnancy show atypical autonomic nervous system modulation of heart rate that is associated with a decrease in spontaneous fetal heart rate accelerations in late gestation. Implications for cardiovascular nursing practice include the monitoring of maternal cardiac autonomic function during pregnancy, especially during standing, as well as a need for continued surveillance of maternal cardiovascular function following pregnancy. The negative effect on fetal heart rate accelerations has implications for the interpretation of standardized obstetrical tests of fetal well-being.

Maturation of fetal responses to music.

Maturation of fetal response to music was characterized over the last trimester of pregnancy using a 5-minute piano recording of Brahms' Lullaby, played at an average of 95, 100, 105 or 110 dB (A). Within 30 seconds of the onset of the music, the youngest fetuses (28-32 weeks GA) showed a heart rate increase limited to the two highest dB levels; over gestation, the threshold level decreased and a response shift from acceleration to deceleration was observed for the lower dB levels, indicating attention to the stimulus. Over 5 minutes of music, fetuses older than 33 weeks GA showed a sustained increase in heart rate; body movement changes occurred at 35 weeks GA. These findings suggest a change in processing of complex sounds at around 33 weeks GA, with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses.

An exploratory study of fetal behavior at 33 and 36 weeks gestational age in hypertensive women.

The relationship between maternal blood pressure (BP) and fetal behaviors as well as differential spontaneous and vibroacoustic elicited fetal behaviors were examined in hypertensive (n = 21) compared to normotensive (n = 22) women at 33 and 36 weeks gestational age (GA). Maternal BP was negatively related to GA at birth and birth weight. On average, fetuses of hypertensive women were born 2 weeks earlier (38 weeks GA) and 340 g lighter. Maternal systolic BP was negatively related to the number of spontaneous body movements observed on ultrasound scan over 20 min and the magnitude of the fetal heart rate (FHR) acceleration elicited by a vibroacoustic stimulus. At 36 weeks GA, vibroacoustic stimulation elicited differential responding with fetuses in the hypertensive compared to the normotensive group having fewer body movements, a lower magnitude of FHR acceleration, and a lack of cardiac-body movement coupled responses. These findings suggest a relationship between maternal BP and fetal behaviors and differential functional development of sensory-motor response systems which need to be characterized in the subgroups of hypertensive disorders observed during pregnancy.

Maturation of fetal heart rate and body movement in 24-33-week-old fetuses threatening to deliver prematurely.

Maturation of spontaneous cardiac and body movement behavior from 24 to 33 weeks gestational age was characterized prospectively in 168 high-risk fetuses threatening to deliver prematurely. Forty-eight, low-risk fetuses delivering as healthy full-term infants served as a comparison group. Fetuses were classified on the basis of gestational age at time of testing and newborn outcome following delivery (high-risk: premature compromised, premature healthy, term healthy infant; low-risk term healthy). In the high-risk group, the average fetal heart rate was greater and decreased over gestation from 148 to 140 bpm, regardless of outcome. In the low-risk group, it decreased from 145 to 138 bpm. In high- and low-risk groups, the average number of heart rate accelerations greater than or = 15 bpm increased over gestation from 2-3 to 8 while the average number of maternally perceived movements decreased. It was concluded that maturational changes in spontaneous fetal heart rate and maternally perceived body movements in fetuses threatening to deliver prematurely parallel those of low-risk fetuses.

Maturation of human fetal responses to airborne sound in low- and high-risk fetuses.

The purpose of the study was to characterize the onset and maturation of airborne sound-elicited responses in low- and high-risk preterm fetuses. In Study 1, a total of 91 low-risk fetuses at 27, 30, 33, and 36 weeks GA received three sound trials at 90, 100, 105 and 110 dB and three no-stimulus control trials. The onset of cardiac acceleration and body movement responses occurred at 30 weeks GA. Maturation of the cardiac response was observed with a decrease in threshold from 105-110 dB at 33 weeks GA to 100-105 dB at 36 weeks GA. In Study 2, the procedure was similar except that the 43 high-risk fetuses at 27, 30 and 33 weeks GA did not receive sounds at 90 dB. For the high-risk fetuses, the onset of cardiac and motor responses also occurred at 30 weeks GA. At 33 weeks GA, those high-risk fetuses subsequently born at term showed an increased magnitude of the cardiac acceleration response compared to low-risk fetuses. The results indicate that both low- and high-risk fetuses begin responding to sounds at the same gestational age. Differential responses observed over gestation in the high-risk group most likely indicate differential functional development of the auditory-response system.

Does PBL Matter? Relations Between Instructional Context, Learning Strategies, and Learning Outcomes.

Purpose: To compare learning strategies used in Problem based learning (PBL) and lectures, and the relations between learning strategies and learning outcomes to determine how different learning strategies associated with PBL and lectures contribute to aspects of clinical competence. Design: The 52-item learning strategies questionnaire was given to preclinical medical students during lecture and PBL sessions in first and third year from 1994 to 1998. Response patterns were compared across the two contexts and factor structures investigated. Regression analyses examined relations between learning strategies and outcomes. Main Outcome Measures/Results: Comparison of responses on the 326 complete pairs of lecture and PBL questionnaires indicated differences at the 0.05 level on 44 of the 52 items. The mean differences were greater than 0.5 (on a 5 point scale) at the 0.001 level for 20 items. Of these, five strategies were used more often in PBL and 15 in lectures. Comparisons of learning strategy use across years showed significant changes with time in both instructional contexts. Principal component analysis revealed a stable factor structure with 4 factors distinctly associated with PBL and 4 factors with the lecture learning context. The remaining 6 factors were mixed and independent of context. Exploratory regression analysis revealed that learning outcomes in examinations were influenced by learning strategies. Multiple choice performance was positively predicted by learning associated with lecture class notes and negatively by group work, whereas the OSCE (objective structured clinical exam) performance was positively predicted by class participation in PBL, self-directed note making and lecture class notes. Conclusion: We have developed a learning strategies questionnaire that shows that students' learning strategies are influenced by instructional context, and patterns of learning strategy use change over time. There is tentative evidence that the students' learning strategies influence learning outcomes.

Maturation of body and breathing movements in 24-33 week-old fetuses threatening to deliver prematurely.

Maturation of spontaneous fetal body and breathing movements of 24- to 33-week-old fetuses in 168 pregnancies threatening to deliver prematurely were examined on the basis of newborn outcome (premature compromised, premature healthy, term healthy). Maturation of fetuses in 60 low-risk pregnancies delivering as healthy full-term infants served as a normative comparison group. Each fetus was observed for 30 min; the amount of body and breathing movements were noted and an estimation of amniotic fluid volume was made. The pattern of behavioural maturation was similar for all outcome groups; with advancing gestation there was a decrease in body movements and an increase in breathing movements. Both reduced activity levels and advanced behaviours were observed in the high-risk outcome groups. The high-risk fetuses had reduced levels of body movements which increased with better outcome and, an earlier onset of increased amounts of breathing, occurring at 30 weeks in contrast to 33 weeks for the comparison group. In the presence of ruptured membranes, those high-risk fetuses who were born prematurely had less breathing compared to those who delivered at term. Similar maturation patterns among high- and low-risk outcome groups suggests normal/typical functional development in the high-risk fetal groups. The observed differential behaviours were associated with prematurity and most likely associated with events leading to premature labour.

The still-face effect in Chinese and Canadian 3- to 6-month-old infants.

Studies conducted in China examining cross-cultural differences in 3- to 6-month-olds used the still-face paradigm. In each study, 20 infants were in the experimental group (normal, still-face, normal interactions) and 20 in the control (3 normal periods). In Study 1, infants interacted with either their mother or their father; they looked and smiled less to the still-face of both parents. In Study 2, infants interacted with both their mother and a stranger, with order counterbalanced. Experimental groups showed similar still-face effects to both adults. The control group responded similarly to the stranger in both orders but responded less to their mother when she interacted 2nd. The data were compared with archival data from Canadian infants. Although Chinese infants took longer to begin smiling, responding was similar in both cultures, despite differences in mothers' behavior: Chinese mothers played with the infants' arms; Canadian mothers played with the legs.

Swaddling after heel lance: age-specific effects on behavioral recovery in preterm infants.

We examined responses of preterm infants to swaddling after a heel lance. Fifteen preterm infants from two postconceptional age (PCA) groups (Group 1: n = 7, PCA < 31 wk; Group 2: n = 8, PCA > or = 31 wk) were observed for 30 minutes during blood sampling followed by routine care; blood sampling followed by swaddling; and no blood sampling and routine care. In both groups, blood sampling resulted in concurrent increases in heart rate and state of arousal, in negative facial displays, and in reductions in blood oxygensaturation. After the blood was drawn, infants less than 31 weeks PCA exhibited an immediate and spontaneous return to behavioral patterns similar to those observed during the no-blood-sample condition, regardless of treatment condition. Infants 31 weeks PCA or older exhibited protracted behavioral disturbance that was significantly reduced by the use of swaddling. We discuss the significance of these findings.

Infant sensitivity to adult eye direction.

Adult eye direction was manipulated while adults interacted with 3-6 month-olds over closed-circuit television (Experiment 1) or in person (Experiment 2). Infants received 4 1-min interaction periods. For experimental groups, adult eye contact was maintained during Periods 1 and 3, and averted during Periods 2 and 4 (by viewing infants on a television monitor to maintain contingency). Control infants received eye contact during all periods. Experimental infants' smiling declined whenever adults looked away; their visual attention simply decreased across periods. Control infants showed little change in gaze or smiling across periods. The implications of these results for Baron-Cohen's model of infant theory of mind and Morton and Johnson's 2-process theory of infant face perception are discussed.

Discharge functional capacity and self-efficacy of men after coronary artery bypass graft surgery.

Fatigue and activity intolerance are reported to persist for several weeks after discharge after coronary artery bypass graft (CABG) surgery. This may be due to early discharge, which limits the time, prior to leaving hospital, to achieve an adequate functional level for the performance of many activities of daily living. Alternatively, it may be related to level of self-confidence, or self-efficacy (SE), in one's ability to perform physical activity. High SE may result in overexertion during the vulnerable, early post-discharge phase of recovery, whereas low SE may cause underexertion. The limited number of cardiac rehabilitation programs in Canada for this phase of recovery precludes close guidance and monitoring during physical activity for most patients. Prior to prescribing safe and effective home exercise at discharge, it is essential to assess functional level, cardiovascular responses to physical activity, and perceived level of confidence in ability to perform physical activity. The purpose of this descriptive study was to measure functional capacity, hemodynamic responses to low level exercise, and self-efficacy at discharge after CABG surgery. Twenty-one men completed a self-efficacy questionnaire (SEQ) and a low-level graded exercise test (LL-GXT) using a modified Naughton protocol, on the day of discharge. Results revealed that discharge functional capacity ranged from 1.0 METs to 4.3 METs, peak heart rate ranged from 82-150 beats.min-1, and peak systolic blood pressure from 114-200 mmHg. Subjects were more confident in their ability to tolerate psychological stressors than physical activity. Furthermore, there was no correlation between SE for physical activity and the physiological variables except HR.(ABSTRACT TRUNCATED AT 250 WORDS)