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Intertidal mussels experience prolonged emersion during low tide, followed by rapid submergence cooling during high tide, causing temperature-induced stress responses. This study examined variations in heart rate to investigate the relationship between emerged and submerged thermal stress in Mediterranean mussels Mytilus galloprovincialis and brown mussels Perna perna from one site on a south coast warm-water coastline and two sites on a west coast cold-water coastline in South Africa. Gaping behaviour in air displayed by P. perna appears to contribute towards their survivability under warmer conditions, as their flatline temperature was higher as compared with M. galloprovincialis, which do not display gaping behaviour. Warm-water acclimatised mussels of both species appeared better able to survive higher temperatures than cold-water acclimatised mussels. However, both mussel species are possibly living at their upper thermal tolerance based on their sublethal Arrhenius breakpoint temperature (ABT). The values of ABT were higher while exposed to air than when submerged, revealing physiological mechanisms at work to cope with changes in the intertidal zone. [ABSTRACT FROM AUTHOR]

Objectives and Participants: Changes in body weight, composition, and size were examined in college freshmen at the beginning (initial, n = 240) and end of fall semester 2007 (n = 214) and the end of spring semester 2008 (n = 205). Methods: Height, weight, body composition, and waist and hip measurements were assessed. Results: Mean weight, body mass index (BMI), absolute and percent body fat all increased significantly over fall semester and the academic year. About 31% of freshmen lost >/=5 lbs. Mean academic year weight gain was 2.6 lbs (entire group) and 6.0 lbs (weight gainers); body fat increased by 4.4 lbs in the weight gainers. A significant correlation (r = .509) was found between weight change and waist circumference change, but not between weight change and waist to hip ratio change. Conclusions: Freshmen weight gain is associated with increases in body fat and waist circumference, which may be troublesome should the trend continue throughout college. [ABSTRACT FROM AUTHOR]

The objectives of this study were to examine changes in body weight, body mass index (BMI), body composition, and shape in a group of male and female students over the 4-year college period. Anthropometric assessments including height and weight (via standard techniques), body composition (via bioelectrical impedance analysis), and body shape (via 3-dimensional body scanning) were conducted at the beginning of the freshman year and end of the senior year in 131 college students. Four-year changes included significant (p < 0.0001) gains in weight (3.0 kg), BMI (1.0 kg·m(-2)), body fat (3.6%), and absolute fat mass (3.2 kg). Males gained significantly (p < 0.0001) greater amounts of weight, BMI, percent and absolute fat mass, and fat-free mass than females. Weight change ranged from (-)8.7 to (+)16.8 kg. About 70% of the participants gained weight, which averaged 5.3 kg; significant (p < 0.0001) gains in BMI, fat-free mass, absolute fat mass, and percent body fat and significant (p < 0.0005) increases in neck, chest-bust, waist, hips, seat, and biceps circumferences were also observed in this weight gain group. The percentage of participants classified as overweight-obese increased from 18% to 31%. The number of females and males with ≥30% and 20% body fat, respectively, increased from n = 14 to n = 26 (with n = 4 exhibiting normal weight obesity) over the 4-year period. The waist circumference changes were significantly (p < 0.0001) correlated with both weight and percent body fat changes. In conclusion, the increasing prevalence of obesity and normal weight obesity among this college population suggests the need for additional health promotion strategies on college campuses.

Obesity and high body fat percentages are a major public health issue. The percentage of obese and overweight Americans has increased over the past 30 years. On average, overweight individuals with higher percent body fat than normal weight individuals are at increased risk for numerous negative outcomes both physically and mentally. A prime time to investigate changes in body composition and associated psychological influences on decision making is during the emerging adulthood period. The first few years of college are a time when adolescents begin to regulate for themselves their own eating behaviors. Previous research shows that freshmen gain weight and increase in percent body fat during their first year of college. The current study addresses the limitations of previous research by investigating (1) individual growth in percent body fat over a longer period of time in college than previous available research and (2) important psychological and sex differences in this growth. This study measures percent body fat across the first 3 years of college at 8 time points for 542 undergraduates (351 females, 65 %; 191 males, 35 %). Longitudinal data analysis was conducted to identify changes in percent body fat, psychological predictors of those changes, and how changes differ for males and females. Our study found that significant increases exist in percent body fat during undergraduates' college years and that change differs for males and females. In addition, through the use of nested hierarchical models, eating regulation style (autonomous or controlled regulation), appearance schema (self-evaluative salience or motivational salience), and body satisfaction were identified as influential predictors of change in percent body fat. For example, young females, who do not feel in control of their physical appearance yet spend a great deal of time maintaining their appearance, have the highest initial body fat percentage and the steepest increase in percent body fat. Overall, males and females with high autonomous regulation and high motivational salience are likely to maintain (instead of increase) percent body fat over the college years. Knowing the influence of these predictors can be useful for promoting health and intervening with young adults in the college setting and other emerging adults who are not enrolled in postsecondary institutions.

Differences in weight, body mass index (BMI), percent and absolute body fat, fat-free mass, and waist circumference were investigated in a group of males and females during the first three years (from 2007 to 2010) of college. Significant three-year gains were observed for weight 2.1 ± 4.7 kg, BMI 0.7 ± 1.6 kg/m(2), percent body fat 2.7 ± 3.3%, and fat mass 2.3 ± 3.5 kg. A significant loss of fat-free mass, -0.5 kg, was observed among females. Absolute gains in weight, BMI, and percent and absolute body fat were highest during the freshman year, followed by the junior year, and lowest during the sophomore year. Among the 70% of students gaining weight over the three years, weight gain averaged 4.3 kg. The numbers of females with over 30% body fat doubled, and the number of males with over 20% body fat increased fivefold. Initially 15% of students were classified as obese/overweight and 79% normal weight; by the end of the junior year, 24% were obese/overweight and 70% were normal weight. Efforts on college campuses to promote healthy lifestyles among its student population are needed throughout the college years.

Objective: Changes in body weight, composition, and shape were investigated in male and female college students between the freshman and sophomore years., Methods: Changes in weight, body mass index (BMI), percent and absolute body fat and fat-free mass (via bioelectrical impedance), and waist circumference (via body scans) were assessed over the freshman and sophomore years (2007-2009) among 120 students attending a Southern public university., Results: Weight (2.5 and 1.7 lbs) and BMI gains (0.3 and 0.3 kg/m(2)) did not significantly differ between the freshman and sophomore years, respectively. Significantly more percent body fat and fat mass were gained during the freshman (1.9% and 3.3 lbs, respectively) than the sophomore year (0.0% and 0.6 lbs, respectively). Females lost significantly more fat-free mass during the freshman (-0.8 lb) than during the sophomore year (1.0 lb). Changes in waist circumference and weight were significantly correlated. Increases in the percentages of females classified as overweight and with unhealthy body fat amounts and waist circumferences were observed., Conclusion: While the sophomore year was characterized by slightly healthier body composition changes than the freshman year, the gains in weight, fat mass, and waist circumference measurements suggest increased health risks for many college females., (Copyright © 2010 Elsevier Inc. All rights reserved.)

In 1980, NASA-Ames Research Center, Moffett Field, CA, initiated a program to assess flight crew fatigue, determine its potential operational consequences, and provide practical countermeasure suggestions. To assess the extent of the problem, crewmembers were monitored before, during, and after commercial short-haul (fixed-wing and helicopter aircraft), overnight cargo, and long-haul operations. A total of 197 volunteers were studied on 94 trip patterns with 1299 flight segments and 2046 h of flying time. The present paper outlines the program and describes the common methodology used in these studies, which are then presented in detail in the four subsequent papers. The sixth paper offers a synthesis of this work, reviewing the major causes of flight crew fatigue and making specific suggestions about ways to manage it in different operations.

We monitored 32 flight crewmembers before, during, and after 4-9 d commercial long-haul trips crossing up to 8 time zones per 24 h. The average duty day lasted 9.8 h, and the average layover 24.8 h. Layover sleep episodes averaged 105 min shorter than pretrip sleep episodes. However, in two-thirds of layovers, crewmembers slept twice so that their total sleep per 24 h on trips averaged 49 min less than pretrip. Greater sleep loss was associated with nighttime flights than with daytime flights. The organization of layover sleep depended on prior flight direction, local time, and the circadian cycle. The circadian temperature rhythm did not synchronize to the erratic environmental time cues. Consequently, the circadian low point in alertness and performance sometimes occurred in flight. On trip days, by comparison with pretrip, crewmembers reported higher fatigue and lower activation; drank more caffeine; ate more snacks and fewer meals; and there were marked increases in reports of headaches, congested nose, and back pain. Scheduling strategies and countermeasures to improve layover sleep, cockpit alertness, and performance, are discussed.

We studied 32 helicopter pilots before, during, and after 4-5 d trips from Aberdeen, Scotland, to service North Sea oil rigs. On duty days, subjects awoke 1.5 h earlier than pretrip or posttrip, after having slept nearly an hour less. Subjective fatigue was greater posttrip than pretrip. By the end of trip days, fatigue was greater and mood more negative than by the end of pretrip days. During trips, daily caffeine consumption increased 42%, reports of headache doubled, reports of back pain increased 12-fold, and reports of burning eyes quadrupled. In the cockpits studied, thermal discomfort and high vibration levels were common. Subjective workload during preflight, taxi, climb, and cruise was related to the crewmembers' ratings of the quality of the aircraft systems. During descent and approach, workload was affected by weather at the landing site. During landing, it was influenced by the quality of the landing site and air traffic control. Beginning duty later, and greater attention to aircraft comfort and maintenance, should reduce fatigue in these operations.

We monitored 74 crewmembers before, during, and after 3-4-d commercial short-haul trips crossing no more than one time zone per 24 h. The average duty day lasted 10.6 duty hours, with 4.5 flight hours and 5.5 flights. On trips, crewmembers slept less, woke earlier, and reported having more difficulty falling asleep, with lighter, less restful sleep than pretrip. The consumption of caffeine, alcohol, and snacks increased on trip days, as did reports of headaches, congested nose, and back pain. The study suggests the following ways of reducing fatigue during these operations: base the duration of rest periods on duty hours as well as flight hours; avoid scheduling rest periods progressively earlier across a trip; minimize early duty report times; and inform crewmembers about strategic use of caffeine and alternatives to alcohol for relaxing before sleep.

We monitored 34 B-727 crewmembers before, during, and after 8-d commercial overnight cargo trips crossing no more than one time zone per 24 h. Daytime sleep episodes were 41% shorter and were rated as poorer than nighttime sleep episodes. When the layover was long enough, crewmembers usually slept again in the evening before going back on night duty. Nevertheless, the total sleep per 24 h on duty days averaged 1.2 h less than pretrip. The circadian temperature rhythm did not adapt completely to night duty, delaying by about 3 h. Self-rated fatigue was highest around the time of the temperature minimum, which occurred near the end of the nighttime duty period. On trip days, crewmembers ate more snacks and there was a marked increase in reports of headaches, congested noses, and burning eyes. Comparisons with daytime short-haul operations confirm that a daytime rest period does not represent the same sleep opportunity as a nighttime rest period of the same duration. We examine regulatory and scheduling options, and personal countermeasure strategies, that could help to reduce sleep loss during overnight cargo operations.

Age-related changes in trip-induced sleep loss, personality (n = 205), and the pre-duty temperature rhythm (n = 91) were analyzed in crews from various flight operations. Eveningness decreased with age (subjects aged 20-30 were more evening-type than subjects over 40). The minimum of the baseline temperature rhythm occurred earlier with age (earlier in subjects aged 30-50 than in subjects aged 20-30). The amplitude of the baseline temperature rhythm declined with age (greater in subjects aged 20-30 than in subjects over 40). Average daily percentage sleep loss during trips increased with age. Among crewmembers flying longhaul flight operations, subjects aged 50-60 averaged 3.5 times more sleep loss per day than subjects aged 20-30. These studies support previous findings that evening types and subjects with later peaking temperature rhythms adapt better to shift work and time zone changes. Age and circadian type may be important considerations for duty schedules and fatigue countermeasures.

Heart rate and core temperature are elevated by physical activity and reduced during rest and/or sleep. These masking effects may confound interpretation of rhythm waveforms, particularly in situations where the rest-activity rhythm has a different period from that of the core temperature rhythm. Such desynchronization often occurs temporarily as an individual adjusts to a new work shift or to a new time zone following rapid transmeridian travel, making it difficult to assess the impact of such schedule changes on the circadian system. The present experiments were designed to estimate the magnitude of these masking effects, by monitoring the heart rate, rectal temperature, and nondominant wrist activity (2-min samples) of 12 male subjects during 6 days of normal routine outside the lab and during 6 days of strict bedrest. Subjects also kept sleep, dietary, and exercise logs throughout the study. Average (20-min) waveforms were computed for each subject and each rhythm, at home and in bedrest. In addition, data were partitioned according to self-reported sleep and wake times and were analyzed separately for each state. Average waveform comparisons indicated that about 45% of the range of the circadian heart rate rhythm during normal routine was attributable to the masking effects of activity during wake, which also produced a 16% elevation in mean heart rate during wake and an 11% increase in mean heart rate overall. (Analysis of variance indicated that mean heart rate during sleep at home was not significantly different from the mean during sleep in bedrest.) On average, about 14% of the range of the circadian temperature rhythm during normal routine was attributable to the effects of activity masking. However, the change in range of the temperature rhythm, from home to bedrest, was very variable between subjects (-41% to +13%). This variability was not accounted for by age or by reported frequency of exercise at home. Normal activity during wake increased the mean temperature during wake by an average of 0.16 degrees C and the overall mean by about 0.12 degrees C. (Analysis of variance indicated that mean temperature during sleep at home was not significantly different from the mean during sleep in bedrest.) A 10-hr "night" (lights-off from 2200 to 0800 hr) was provided during bedrest, within which subjects could select their own sleep times. Times of sleep onset and wake onset were not significantly different between home and bedrest.(ABSTRACT TRUNCATED AT 400 WORDS)

An international research team has carried out an electroencephalographic study of sleep and wakefulness in flight crews operating long-haul routes across seven or eight time zones. Following baseline recordings, volunteer crews (n = 56) from four airlines spent their first outbound layover at a sleep laboratory. This paper provides an overview of the project's history, its research design, and the standardization of procedures. The overall results are remarkably consistent among the four participating laboratories and strongly support the feasibility of cooperative international sleep research in the operational arena.