Quantifying snowfall from orographic cloud seeding.

Climate change and population growth have increased demand for water in arid regions. For over half a century, cloud seeding has been evaluated as a technology to increase water supply; statistical approaches have compared seeded to nonseeded events through precipitation gauge analyses. Here, a physically based approach to quantify snowfall from cloud seeding in mountain cloud systems is presented. Areas of precipitation unambiguously attributed to cloud seeding are isolated from natural precipitation (<1 mm h-1). Spatial and temporal evolution of precipitation generated by cloud seeding is then quantified using radar observations and snow gauge measurements. This study uses the approach of combining radar technology and precipitation gauge measurements to quantify the spatial and temporal evolution of snowfall generated from glaciogenic cloud seeding of winter mountain cloud systems and its spatial and temporal evolution. The results represent a critical step toward quantifying cloud seeding impact. For the cases presented, precipitation gauges measured increases between 0.05 and 0.3 mm as precipitation generated by cloud seeding passed over the instruments. The total amount of water generated by cloud seeding ranged from 1.2 × 105 m3 (100 ac ft) for 20 min of cloud seeding, 2.4 × 105 m3 (196 ac ft) for 86 min of seeding to 3.4 x 105 m3 (275 ac ft) for 24 min of cloud seeding.

Precipitation formation from orographic cloud seeding.

Throughout the western United States and other semiarid mountainous regions across the globe, water supplies are fed primarily through the melting of snowpack. Growing populations place higher demands on water, while warmer winters and earlier springs reduce its supply. Water managers are tantalized by the prospect of cloud seeding as a way to increase winter snowfall, thereby shifting the balance between water supply and demand. Little direct scientific evidence exists that confirms even the basic physical hypothesis upon which cloud seeding relies. The intent of glaciogenic seeding of orographic clouds is to introduce aerosol into a cloud to alter the natural development of cloud particles and enhance wintertime precipitation in a targeted region. The hypothesized chain of events begins with the introduction of silver iodide aerosol into cloud regions containing supercooled liquid water, leading to the nucleation of ice crystals, followed by ice particle growth to sizes sufficiently large such that snow falls to the ground. Despite numerous experiments spanning several decades, no direct observations of this process exist. Here, measurements from radars and aircraft-mounted cloud physics probes are presented that together show the initiation, growth, and fallout to the mountain surface of ice crystals resulting from glaciogenic seeding. These data, by themselves, do not address the question of cloud seeding efficacy, but rather form a critical set of observations necessary for such investigations. These observations are unambiguous and provide details of the physical chain of events following the introduction of glaciogenic cloud seeding aerosol into supercooled liquid orographic clouds.

Reliability and Validity of the 6-Minute Step Test for Clinical Assessment of Cardiorespiratory Fitness in People at Risk of Cardiovascular Disease.

Giacomantonio, N, Morrison, P, Rasmussen, R, and MacKay-Lyons, MJ. Reliability and validity of the 6-minute step test for clinical assessment of cardiorespiratory fitness in people at risk of cardiovascular disease. J Strength Cond Res 34(5): 1376-1382, 2020-The purpose of this study was to determine the test-retest reliability and validity of the 6-minute step test (6MST) as a potential assessment of cardiorespiratory fitness (CRF) of people at risk of cardiovascular disease (CVD). A prospective, cross-sectional, correlational study design was used. A single cohort of 30 adults with 2 or more risk factors for CVD was recruited. Exercise tests were scheduled on 2 days, separated by 1 week. Validity was determined by comparing 6MST results with those obtained in a symptom-limited treadmill test and the 6-minute walk test (6MWT). Main outcome variables were peak heart rate (HRpeak) and peak oxygen consumption (V[Combining Dot Above]O2peak) measured during the 6MST, treadmill test, and 6MWT. Test-retest reliability of HRpeak and V[Combining Dot Above]O2peak during the 6MST was very strong (intraclass correlation coefficient [ICC], 0.92; 95% confidence interval [CI], 0.83-0.97 and ICC, 0.93; 95% CI, 0.84-0.97, respectively). Correlations were also very strong between 6MST and treadmill test HRpeak (r = 0.81) and between 6MST and treadmill test V[Combining Dot Above]O2peak (r = 0.88). Correlations were moderate between 6MST HRpeak and 6MWT steady-state HR (r = 0.57) and strong between 6MST V[Combining Dot Above]O2peak and 6MWT steady-state V[Combining Dot Above]O2 (r = 0.70). The 6MST seems to be a reliable, valid option for assessing CRF of people at risk of CVD in a broad range of clinical settings. Providing practical, accessible tests will help facilitate the goal of establishing CRF as a clinical vital sign. The next step in the development of the 6MST should be to identify the most appropriate 6MST predictor variables to estimate V[Combining Dot Above]O2max.

Dual-energy x-ray absorptiometry to measure the influence of a 16-week community-based swim training program on body fat in children and adolescents with intellectual disabilities.

OBJECTIVE: To use dual-energy x-ray absorptiometry (DXA) to measure the effects of a 16-week community-based swim training program on percent body fat in children and adolescents with intellectual disability (ID). DESIGN: Convenience sample. SETTING: University sport complex and exercise science laboratory. PARTICIPANTS: Children and adolescents (n=8; mean age +/- SD, 13.1 +/- 3.4 y), 2 girls and 6 boys with ID, of varying fat levels (11%-35%). INTERVENTION: A swim training program lasting for the duration of 16 weeks with three 1-hour sessions held at a 25-m pool each week. MAIN OUTCOME MEASURE: Assessing percent body fat at pretest and posttest through the use of DXA. RESULTS: After the 16-week exercise training program, we observed a 1.2% median increase in body fat percentage with a range from -0.3% to 4.5%. Wilcoxon matched-pairs signed-ranks tests suggest that these results are statistically significant (P=.039; exact). CONCLUSIONS: Exercise training alone proved ineffectual in reducing percent body fat in 8 children and adolescents with ID. Further research should consider implementing a combined diet and exercise program. To gauge the effectiveness of intervention programs, valid methods and complex measurement tools such as DXA should be used to assess changes in percent body fat in such a heterogeneous population.

Physical activity and body mass index in grade 3, 7, and 11 Nova Scotia students.

PURPOSE: This study examined the average time spent in moderate or more intense physical activities according to weight status in randomly selected Nova Scotia students. METHODS: A total of 1653 students participated in this study: 575 in grade 3, 558 in grade 7, and 520 in grade 11. Physical activity was measured for seven consecutive days using MTI accelerometers. Activity counts were classified according to moderate (3-5.9 METs), hard (6-8.9 METs), and very hard (>9 METs) intensities. Height and weight were measured and body mass index (BMI) calculated. Centers for Disease Control and Prevention BMI criteria for age and sex were used to classify the students as normal weight (< or =85th percentile), at risk of overweight (>85th and < or =95th percentiles), and overweight (>95th percentile). ANOVA was used to compare the average time spent in moderate, hard, and very hard physical activities according to BMI status in boys and girls in grades 3, 7, and 11. RESULTS: Although age and sex differences existed, there were no significant differences in the average time spent in moderate or more intense physical activities in the BMI groups. CONCLUSION: Further research is warranted to elucidate the factors surrounding the relationship between physical activity and BMI in children and youths.

A comprehensive exercise program for a young adult male with Down syndrome who experienced a stroke.

PURPOSE: Individuals with Down syndrome (DS) may be at heightened risk for stroke due to a combination of physiological conditions and lifestyle choices. There remains a lack of information regarding the effectiveness of exercise training on individuals with DS post-stroke. This case report describes the effects of a comprehensive exercise program on an individual with DS who had sustained a stroke. METHOD: A 20-year-old male with DS recovering from a left hemorrhagic stroke 18 months previous underwent a 12-week land and water-based program 60 minutes/session, 5 sessions/week. Exercise sessions addressed specific limitations, including cardiorespiratory fitness, generalized muscle weakness, balance deficits, and reduced ambulatory ability in terms of speed, gait pattern and walking tolerance. RESULTS: Between the baseline and 6-month follow-up assessments improvements were noted in peak oxygen consumption (VO2peak, 8% increase), one-repetition maximum (51%), community balance and mobility scale (54%), comfortable walking speed (42%), six-minute walk test (28%) and daily step count (21%). CONCLUSION: Improved cardiorespiratory fitness, strength, balance and mobility provide preliminary evidence of the trainability of individuals with both DS and stroke. Future studies are warranted to investigate the role of exercise in risk factor reduction for primary and secondary prevention of stroke in people with DS. Implications for Rehabilitation Individuals with Down syndrome (DS) may be at heightened risk of stroke due to a combination of physiological conditions and lifestyle choices which contribute to reduced exercise capacity, accelerated aging patterns, moyamoya syndrome and physical inactivity as well as high rates of obesity and related conditions. More intensive fitness programs may be particularly important for people with both DS and stroke. Participation in a comprehensive exercise program can be safe and effective in regaining pre-stroke levels of cardiorespiratory fitness, functional mobility and goal attainment. RESULTS suggest that a more intensive physical therapy regimen may be recommendable during out-patient rehabilitation for individuals with DS post-stroke.

Reduction measures and percent body fat in individuals with intellectual disabilities: a scoping review.

BACKGROUND: Individuals with intellectual disability (ID) may be more obese and extremely obese than individuals without ID. There remains an on-going debate as to the effectiveness of exercise training in decreasing body fat in different populations. OBJECTIVE: This scoping review explored the effects of exercise training interventions on percent body fat in individuals with ID. METHODS: Authors conducted electronic searches through PubMED (1978 to present) and SPORT Discus (1975 to present) and evaluated relevant articles independently based on guidelines for scoping reviews. RESULTS: Few exercise interventions have targeted changes in percent body fat. Based on the 11 articles identified, exercise interventions appear effective at maintaining fat levels but have been largely unsuccessful at reducing body fat following training. Only 18% of exercise alone studies produced positive changes in body fat outcomes among individuals with ID. CONCLUSIONS: Greater focus should be placed on the metabolic health of individuals with ID. Results call into question methods used to date. These findings may be a consequence of the minimal attention paid to nutritional status and also a lack of standardized anthropometric methods and acceptable guidelines for categorizing adiposity based on health risk in this population. Further research is needed to promote more effective and sustainable strategies aimed at combating the elevated levels of body fat.

Dual-energy x-ray absorptiometry to measure the effects of a thirteen-week moderate to vigorous aquatic exercise and nutritional education intervention on percent body fat in adults with intellectual disabilities from group home settings.

People with intellectual disability are more likely to be obese and extremely obese than people without intellectual disability with rates remaining elevated among adults, women and individuals living in community settings. Dual-energy X-ray absorptiometry measured the effects of a 13-week aquatic exercise and nutrition intervention on percent body fat in eight adults with intellectual disabilities (aged 41.0 ± 13.7 yrs) of varying fat levels (15%-39%) from two group homes. A moderate to vigorous aquatic exercise program lasted for the duration of 13 weeks with three, one-hour sessions held at a 25m pool each week. Nutritional assistants educated participants as to the importance of food choice and portion size. A two-tailed Wilcoxon matched-pairs signed-ranks test determined the impact of the combined intervention on body fat percentage and BMI at pre and post test. Median body fat percentage (0.8 %) and BMI (0.3 kg/m(2)) decreased following the exercise intervention, but neither were statistically significant, p = .11 and p = .55, respectively. The combined intervention was ineffective at reducing percent body fat in adults with intellectual disability according to dual-energy X-ray absorptiometry. These results are in agreement with findings from exercise alone interventions and suggest that more stringent nutritional guidelines are needed for this population and especially for individuals living in group home settings. The study did show that adults with intellectual disability may participate in moderate to vigorous physical activity when given the opportunity.

Formation and spread of aircraft-induced holes in clouds.

Hole-punch and canal clouds have been observed for more than 50 years, but the mechanisms of formation, development, duration, and thus the extent of their effect have largely been ignored. The holes have been associated with inadvertent seeding of clouds with ice particles generated by aircraft, produced through spontaneous freezing of cloud droplets in air cooled as it flows around aircraft propeller tips or over jet aircraft wings. Model simulations indicate that the growth of the ice particles can induce vertical motions with a duration of 1 hour or more, a process that expands the holes and canals in clouds. Global effects are minimal, but regionally near major airports, additional precipitation can be induced.

Effects of Hot or Cold Water Immersion and Modified Proprioceptive Neuromuscular Facilitation Flexibility Exercise on Hamstring Length.

OBJECTIVE: To compare the changes in hamstring length resulting from modified proprioceptive neuromuscular facilitation flexibility training in combination with cold-water immersion, hot-water immersion, and stretching alone. DESIGN AND SETTING: Training-only subjects stood motionless for 10 minutes, while subjects in the cold group stood in a cold-water bath (8 degrees +/- 1 degrees C) immersed up to the gluteal fold for 10 minutes, and subjects in the hot group stood in a hot-water bath (44 degrees +/- 1 degrees C) immersed up to the gluteal fold for 10 minutes. All subjects exercised only the right lower limb using a modified proprioceptive neuromuscular facilitation flexibility protocol, consisting of 1 set of 4 repetitions. This procedure was followed for 5 consecutive days. SUBJECTS: Forty-five uninjured subjects (21 women, 24 men; age range, 18-25 years) were randomly assigned to the cold, hot, or stretching-alone group. MEASUREMENTS: Subjects were measured for maximum active hip flexion on the first and fifth days. RESULTS: Group results were assessed using a 2 x 3 analysis of variance, comparing changes in hamstring length from pretest to posttest. All 3 groups had significant improvements in hamstring length (pretest to posttest) (P <.05). However, no significant differences occurred among groups. CONCLUSIONS: No advantage was apparent in using complete hot or cold immersion to increase hamstring length in healthy subjects.