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Sample records for birth ball exercise

  1. Efficacy of birth ball exercises on labour pain management.

    Science.gov (United States)

    Leung, R W C; Li, J F P; Leung, M K M; Fung, B K Y; Fung, L C W; Tai, S M; Sing, C; Leung, W C

    2013-10-01

    To evaluate the efficacy of a birth ball exercise programme conducted by physiotherapists on pain relief, psychological care, and facilitation of the labour process at a labour ward in a regional hospital. Case series with before-after comparisons. Kwong Wah Hospital, Hong Kong. Chinese women admitted to the labour ward for spontaneous vaginal delivery between April and August 2012 were recruited. Physiotherapists taught birth ball exercises in groups or individually for 30 minutes. Labour pain intensity, back pain intensity, frequency of labour pain, stress and anxiety levels, and subjective pressure level over the lower abdomen were captured before and after birth ball exercises. Most of the parameters were measured using self-reported visual analogue scales. After the exercise session, physiotherapists measured the women's satisfaction level. Midwives recorded pethidine usage. A total of 203 pregnant women participated in this programme; 181 were in the latent phase group, whereas 22 were categorised into the no-labour-pain group. In both groups, there were statistically and clinically significant differences in back pain level, stress and anxiety levels, as well as pressure level over the lower abdomen before and after the exercise (Plabour pain and frequency of labour pain were demonstrated. Mean satisfaction scores were high, with visual analogue scale scores higher than 8.2 in both groups. Pethidine usage showed a further decreasing trend (6.4%) compared with the past 2 years. Birth ball exercise could be an alternative means of relieving back pain and labour pain in the labour ward, and could decrease pethidine consumption in labouring women.

  2. Effects of birth ball exercise on pain and self-efficacy during childbirth: a randomised controlled trial in Taiwan.

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    Gau, Meei-Ling; Chang, Ching-Yi; Tian, Shu-Hui; Lin, Kuan-Chia

    2011-12-01

    To examine the effectiveness of a birth ball exercise programme during childbirth by measuring childbirth self-efficacy and childbirth pain. In addition, it tested the mediating effects of childbirth self-efficacy on the relationship between the birth ball exercise programme and childbirth pain. Randomised controlled trial. The study was conducted from December 2008 to November 2009, at two birth units, one at a regional hospital and one at a medical centre, with 600 and 1022 annual births, respectively. One hundred and eighty-eight expectant mothers were recruited (recruitment rate: 47%) and were allocated by block randomisation into the two arms of the study, but only 48 intervention and 39 control group participants completing the trial. The birth ball exercise programme consisted of a 26-page booklet and a 19-minute videotape, with periodic follow-ups during prenatal checks. All members of the experimental group were asked to practise the exercises and positions at home for at least 20 minutes three times a week for a period of 6-8 weeks. Each woman in the experimental group was given a birth ball for use during labour and encouraged every hour to choose the most comfortable positions, movements, and exercises. Both the experimental and control groups received standard nursing and midwifery care from hospital staff nurses in all aspects of pregnancy and childbirth. When cervical dilations were four centimetres and eight centimetres, the women completed demographic and obstetrics information, the Childbirth Self-efficacy Inventory (CBSEI), and the short form of the McGill Pain Questionnaire (SF-MPQ). Our study revealed that birth ball exercises provided statistically significant improvements in childbirth self-efficacy and pain. Specifically, self-efficacy had a 30-40% mediating effect on relationships between birth ball exercises and childbirth pain. Mothers in the experimental group had shorter first-stage labour duration, less epidural analgesia, and fewer

  3. Birth of ball lightning

    Science.gov (United States)

    Lowke, J. J.; Smith, D.; Nelson, K. E.; Crompton, R. W.; Murphy, A. B.

    2012-10-01

    Many observations of ball lightning report a ball of light, about 10 cm in diameter, moving at about walking speed, lasting up to 20 s and frequently existing inside of houses and even aeroplanes. The present paper reports detailed observations of the initiation or birth of ball lightning. In two cases, navigation crew of aircraft saw ball lightning form at the windscreen inside the cockpit of their planes. In the first case, the ball lightning occurred during a thunderstorm, with much lightning activity outside of the plane. In the second case, large "horns" of electrical corona were seen outside of the plane at the surface of the radome, just prior to the formation of the ball lightning. A third case reports ball lightning formed inside of a house, during a thunderstorm, at a closed glass window. It is proposed, based on two-dimensional calculations of electron and ion transport, that ball lightning in these cases is driven and formed by atmospheric ions impinging and collecting on the insulating surface of the glass or Perspex windows. This surface charge can produce electric fields inside of the cockpit or room sufficient to sustain an electric discharge. Charges of opposite sign to those outside of the window accumulate on the inside surface of the glass, leaving a ball of net charge moving inside of the cockpit or room to produce a pulsed discharge on a microsecond time scale.

  4. Effect of birth ball on labor pain relief: A systematic review and meta-analysis.

    Science.gov (United States)

    Makvandi, Somayeh; Latifnejad Roudsari, Robab; Sadeghi, Ramin; Karimi, Leila

    2015-11-01

    To critically evaluate the available evidence related to the impact of using a birth ball on labor pain relief. The Cochrane library, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE/PubMed and Scopus were searched from their inception to January 2015 using keywords: (Birth* OR Swiss OR Swedish OR balance OR fitness OR gym* OR Pezzi OR sport* OR stability) AND (ball*) AND (labor OR labour OR Obstetric). All available randomized controlled trials involving women using a birth ball for pain relief during labor were considered. The search resulted in 341 titles and abstracts, which were narrowed down to eight potentially relevant articles. Of these, four studies met the inclusion criteria. Pain intensity on a 10 cm visual analogue scale was used as the main outcome measure. Risk of bias was assessed using the Cochrane Risk of Bias tool. Comprehensive Meta-Analysis Version 2 was used for statistical analysis. Four RCTs involving 220 women were included in the systematic review. One study was excluded from the meta-analysis because of heterogeneous interventions and a lack of mean and standard deviation results of labor pain score. The meta-analysis showed that birth ball exercises provided statistically significant improvements to labor pain (pooled mean difference -0.921; 95% confidence interval -1.28, -0.56; P = 0.0000005; I(2)  = 33.7%). The clinical implementation of a birth ball exercise could be an effective tool for parturient women to reduce labor pain. However, rigorous RCTs are needed to evaluate the effect of the birth ball on labor pain relief. © 2015 Japan Society of Obstetrics and Gynecology.

  5. Core muscle activation during Swiss ball and traditional abdominal exercises.

    Science.gov (United States)

    Escamilla, Rafael F; Lewis, Clare; Bell, Duncan; Bramblet, Gwen; Daffron, Jason; Lambert, Steve; Pecson, Amanda; Imamura, Rodney; Paulos, Lonnie; Andrews, James R

    2010-05-01

    Controlled laboratory study using a repeated-measures, counterbalanced design. To test the ability of 8 Swiss ball exercises (roll-out, pike, knee-up, skier, hip extension right, hip extension left, decline push-up, and sitting march right) and 2 traditional abdominal exercises (crunch and bent-knee sit-up) on activating core (lumbopelvic hip complex) musculature. Numerous Swiss ball abdominal exercises are employed for core muscle strengthening during training and rehabilitation, but there are minimal data to substantiate the ability of these exercises to recruit core muscles. It is also unknown how core muscle recruitment in many of these Swiss ball exercises compares to core muscle recruitment in traditional abdominal exercises such as the crunch and bent-knee sit-up. A convenience sample of 18 subjects performed 5 repetitions for each exercise. Electromyographic (EMG) data were recorded on the right side for upper and lower rectus abdominis, external and internal oblique, latissimus dorsi, lumbar paraspinals, and rectus femoris, and then normalized using maximum voluntary isometric contractions (MVICs). EMG signals during the roll-out and pike exercises for the upper rectus abdominis (63% and 46% MVIC, respectively), lower rectus abdominis (53% and 55% MVIC, respectively), external oblique (46% and 84% MVIC, respectively), and internal oblique (46% and 56% MVIC, respectively) were significantly greater compared to most other exercises, where EMG signals ranged between 7% to 53% MVIC for the upper rectus abdominis, 7% to 44% MVIC for the lower rectus abdominis, 14% to 73% MVIC for the external oblique, and 16% to 47% MVIC for the internal oblique. The lowest EMG signals were consistently found in the sitting march right exercise. Latissimus dorsi EMG signals were greatest in the pike, knee-up, skier, hip extension right and left, and decline push-up (17%-25% MVIC), and least with the sitting march right, crunch, and bent-knee sit-up exercises (7%-8% MVIC

  6. EFFECTIVENESS OF FLOOR EXERCISES VERSES BALL EXERCISES ON SPINAL MOBILITY IN SPASTIC DIPLEGIC

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    Sumitra Sakhawalkar

    2017-04-01

    Full Text Available Background: The objective of this present study was to determine the Effectiveness of Floor Exercises versus Ball Exercises on spinal mobility in Spastic Diplegic. Methods: Institutional ethical committee permission was taken before starting the study. A sample of 70 Diplegic CP children was screened, and 40 meeting the inclusion criteria were selected for study were then randomly divided into two groups one control other experimental i.e. 20 in each group by chit method. Both the groups were assessed with spinal goniometry using Tape measurements for Thoracolumbar spine and Modified Schober's Test (MMSTbefore and after the treatment. Control group were given Floor exercise on a mat, and Swiss ball was giving experimental group Ball exercises for ten repetitions with 10-second hold, treatment time was 40 min per session for 3days per week for six weeks. Same sustained stretching technique for both groups in bilateral lower extremities for ten repetitions with 30 sec hold was given for, TA, Iliopsoas, Hamstrings, Hip Adductor, Rectus femoris. Result: Significant improvement was noted in the Intra-group comparison of both the groups from baseline to post six weeks of intervention p-value 0.001*** in both groups, and the Intergroup analysis using with tape measurements for Thoracolumbar spine (p-value and MMST (p-value 0.133NS. Conclusion: The present study concludes that there is a similar effect of both Floor Exercises versus Ball Exercises on spinal mobility in Spastic Diplegic.

  7. Effects of the Horse Riding Simulator and Ball Exercises on Balance of the Elderly

    Science.gov (United States)

    Kim, SeongGil; Yuk, Goon-chang; Gak, Hwangbo

    2013-01-01

    [Purpose] The aim of this study was to examine the effects of horse riding exercise using a horse riding simulator (HRS) and a ball on static and dynamic balance of elderly people. [Methods] Thirty-two elderly people hospitalized in geriatric hospitals were randomly assigned to the HRS exercise group or the ball exercise groups, and they performed exercise for eight weeks. [Results] The length of postural sway during quite standing with and without eyes closed significantly decreased in both groups after the exercises and there was no significant difference between both groups in the Romberg test. In the functional reach test (FRT), there were significant increases in distance in both groups after the exercises, and the distance of the HRS exercise group was significantly greater than that of the ball exercise group. In the Timed Up & Go test (TUG) and Timed 10-meter walk test (10MWT), the time significantly decreased in both groups, and there was a more significant decrease in the HRS exercise group than in the ball exercise group. [Conclusion] The results of this study indicate that HRS and ball exercises may improve the balance and gait ability of elderly people hospitalized in nursing homes or geriatric hospitals. PMID:24396203

  8. EFFECTIVENESS OF TRUNK TRAINING EXERCISES VERSUS SWISS BALL EXERCISES FOR IMPROVING SITTING BALANCE AND GAIT PARAMETERS IN ACUTE STROKE SUBJECTS

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    Kothalanka Viswaja

    2015-12-01

    Full Text Available Background: The aim of this study is to evaluate the effectiveness of trunk training and Swiss ball exercises in acute stroke subjects. Trunk is often neglected part in the stroke rehabilitation, trunk training exercises and Swiss ball exercises result in better recruitment of trunk muscles thus improving sitting balance and gait parameters in acute stroke subjects. However literature evidences for trunk training exercises and Swiss ball exercises in improving sitting balance and gait are scarce in acute stroke population. Methods: A total of 60 subjects who met the inclusion criteria were recruited from department of physiotherapy, G.S.L general hospital and were randomly allocated into 2 groups with 30 subjects in each group. Initially all of them were screened for balance and gait using trunk impairment scale and by assessing gait parameters, after that they were given a 30min of trunk training and Swiss ball exercises for 5 days a week for 4 weeks. Both the groups received conventional physiotherapy for 4 weeks. Results: Post intervention there was no significant difference between the two groups. There was improvement post treatment in trunk training group (P0.5. Conclusion: The results had shown that both groups noted significant difference. But when comparing between these two groups there is no statistical significance noted. So this study concluded that there is no significant difference between trunk training exercises and Swiss ball exercises on sitting balance and gait parameters in subjects with stroke.

  9. EFFECTIVENESS OF SWISS BALL VS FLOOR EXERCISES ON CORE MUSCLE STRENGTH IN ELITE CRICKETERS

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    K. Sai sudha

    2015-10-01

    Full Text Available Background: Cricket is one of the most popular game in India played by men and women of all ages. The increased physical demands on the players may be associated with an increased risk of injuries. Core muscle strength is important to prevent risk of injuries in elite cricketers. The beginners in the cricket must have enough strength of core muscles, as core is the bridge between upper and lower limbs. So, it should be strong enough to prevent low back and lower limb injuries in cricketers. The aim is to determine the effectiveness of swiss ball exercises versus floor exercises on core muscle strength in elite cricketers. The objective is to study and compare the effectiveness of swiss ball exercises and floor exercises in elite cricketers in terms of back strength. Method: The total number of students in this study were 30 eilte cricketers between 16-25 years out of which 15 subjects were included each in floor exercise(n=15 and swiss ball group(n=15. Back strength was measured before and after the intervention of 6 weeks using isokinetic analyser. Results: After the analysis, the results revealed significant improvement of back strength in both the groups(p< 0.00. The swiss ball group showed significant results when compared with floor exercise group. Conclusion: Although the study showed beneficial results in both the groups, the results reflected that swiss ball group had better improvement of core muscle strength than the floor exercise group.

  10. Muscle Activation Among Supine, Prone, and Side Position Exercises With and Without a Swiss Ball.

    Science.gov (United States)

    Escamilla, Rafael F; Lewis, Clare; Pecson, Amanda; Imamura, Rodney; Andrews, James R

    2016-07-01

    Prone, supine, and side position exercises are employed to enhance core stability. Overall core muscle activity would be greater in prone position exercises compared with supine and side position exercises. Controlled laboratory study. Eighteen men and women between 23 and 45 years of age served as subjects. Surface electrodes were positioned over the upper and lower rectus abdominis, external and internal obliques, rectus femoris, latissimus dorsi, and lumbar paraspinals. Electromyography data were collected during 5 repetitions of 10 exercises, then normalized by maximum voluntary isometric contractions (MVIC). Differences in muscle activity were assessed using 1-way repeated-measures analysis of variance, while t tests with a Bonferroni correction were employed to assess pairwise comparisons. Upper and lower rectus abdominis activity was generally significantly greater in the crunch, bent-knee sit-up, and prone position exercises compared with side position exercises. External oblique activity was significantly greater in the prone on ball with right hip extension, side crunch on ball, and side bridge (plank) on toes compared with the prone and side bridge (plank) on knees, the crunch, or the bent-knee sit-up positions. Internal oblique activity was significantly greater in the prone bridge (plank) on ball and prone on ball with left and right hip extension compared with the side crunch on ball and prone and side bridge (plank) on knees positions. Lumbar paraspinal activity was significantly greater in the 3 side position exercises compared with all remaining exercises. Latissimus dorsi activity was significantly greater in the prone on ball with left and right hip extension and prone bridge (plank) on ball and on toes compared with the crunch, bent-knee sit-up, and prone and side bridge (plank) on knees positions. Rectus femoris activity was significantly greater in the prone on ball with left hip extension, bent-knee sit-up, or prone bridge (plank) on toes

  11. Earliest Recollections and Birth Order: Two Adlerian Exercises.

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    Parrott, Les

    1992-01-01

    Presents two exercises designed to demonstrate the influence of two Adlerian principles on personality. Includes exercises dealing with birth order and earliest recollection. Concludes that the exercises actively demonstrate major concepts for counseling courses in Adlerian psychotherapy. Reports that students rated both exercises highly, with…

  12. PACKAGE OF BIRTHING BALL, PELVIC ROCKING, AND ENDORPHIN MASSAGE (BPE DECREASE THE FIRST STEP LABOR PAIN

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    Nila Marwiyah

    2017-08-01

    Full Text Available Background and Purpose: Labor pain is unpleasant and frightening experience for birth mother. In addition, labor pain cause exhaustion and childbirth trauma.Birthing ball, pelvic rocking, and endorphin (B.P.E massage are emerging as non-pharmacology methods of pain management in labor. The aimed of this study was to investigate the effect of package of BPE on labour pain during the first stage of labor. Method: This study was quasi-experiment. Total numbers of samples were 23 mothers who were in the first stage of labor. Samples were selected by using quota sampling technique. Instrument of this study was numeric rating scale (NRS. Result: Data analysis by using paired sample t-test revealed that there were significantly different between before and after the intervention of BPE on labour pain during the first stage of labor in this study (p <0.01.  Conclusion and recommendation: This study showed that BPE is effective as non-pharmacology methods on pain relieve of first stage of labor. Further study need to investigate other variables such as anxiety of birth mother. Key Words: labor pain, package of birth ball, pelvic rocking, and endorphin massage(BPE, labor process.

  13. A COMPARITIVE STUDY TO KNOW THE EFFECTIVENESS OF PRONE BACK EXTENSION EXRECISES AND SWISS BALL EXERCISES ON BACK EXTENSOR MUSCLES PERFORMANCE

    OpenAIRE

    Subhanjan Das; C. K. Senthil Kumar; Abhijit Dutta

    2016-01-01

    Background: Endurance of the back muscles is important for stability of the trunk and therefore essential for normal functioning of an individual. Prone back extension exercises are traditional measures to improve back endurance. More recently Swiss ball exercises have become popular as a means to improve back endurance. Purpose of this study is to compare Prone back extension exercises with back extension exercise on Swiss ball on the improvement of the back extensor muscles performance, and...

  14. Static and dynamic postural loadings during computer work in females: Sitting on an office chair versus sitting on an exercise ball

    NARCIS (Netherlands)

    Kingma, I.; van Dieen, J.H.

    2009-01-01

    Seated computer work results in prolonged static loading, which has been associated with the development of musculoskeletal disorders. A popular alternative to sitting on an office chair while performing computer work is to sit on an exercise ball. Sitting on an exercise ball might affect static and

  15. Static and dynamic postural loadings during computer work in females: Sitting on an office chair versus sitting on an exercise ball

    NARCIS (Netherlands)

    Kingma, I.; van Dieen, J.H.

    2008-01-01

    Seated computer work results in prolonged static loading, which has been associated with the development of musculoskeletal disorders. A popular alternative to sitting on an office chair while performing computer work is to sit on an exercise ball. Sitting on an exercise ball might affect static and

  16. Physical exercise during pregnancy and the risk of preterm birth: a study within the Danish National Birth Cohort

    DEFF Research Database (Denmark)

    Juhl, Mette; Andersen, Per Kragh; Olsen, Jørn

    2008-01-01

    According to many national recommendations, women should be physically active during pregnancy, but empirical evidence to support this recommendation is sparse. The authors' aim in this study was to examine the relation between physical exercise during pregnancy and the risk of preterm birth. Self......-reported data on physical exercise during pregnancy were collected prospectively for 87,232 singleton pregnancies included in the Danish National Birth Cohort between 1996 and 2002. Hazard ratios for preterm birth according to hours of exercise per week, type of exercise, and metabolic equivalent-hours per week...

  17. EFFECT OF SWISS BALL EXERCISE TOWARD THE BODY BALANCE TO LESS THE RISK FALL OF OLDER AT UPT SOCIAL

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    Henny Syapitri

    2017-02-01

    Full Text Available Abstract The balance of body is one of the main factor in doing fungsional activity. In every activity, the body always need control of the body balance, because basically every phisic activity right static or dinamic will take someone on unstable position with big risk to having fell. Swiss Ball exercise as support is believed on labile surface will make spine have big chance to stabling the muscle between vebra and increase the dinamic balance to restrain the repeats stability. The research object to know The Effect of Swiss Ball Exercise toward The Body Balance to Less The Risk Fall of Older at UPT Social Service of Older and Children Under Five district Binjai and Medan in Year 2016. The research type is Quasi Experiment with pre test-post test one group only design method. Population in this research all of older at UPT Social Service district Binjai as much as 172 older with number of man is 81 and woman is 91, with Purposive sampling Technique that is 15 respondences. Data collecting using observation sheet with analysis that used is univariat: respondence characteristics, the body balance of older before and after doing Swiss Ball practice, and bivariat with Paired t-Test. The research result showing the average of body balance before doing Swiss Ball as much (Mean 38,07 and after (Mean 46,33. Conclusion: there is the effect of Swiss Ball toward body balance to less the risk fall of older (p=0,000 ; p=< 0,05. Sugessted for older to practice the balance himself more steady so that not easy to have risk fall further. Influenced, and for the next researcher can research about another factor that foregrounded the risk fall of older. Keywords    : Swiss Ball, Balance Exercise, Risk Fall

  18. Comparison of Trunk Stabilization Exercises Using a Gym Ball and Conventional Back Care Exercises for Patients With Chronic Lower Back Pain

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    Ahmed

    2016-04-01

    Full Text Available Background The trunk muscles are vital for the maintenance of spinal stability. Training of specific muscles surrounding the lumbar spine, which provide dynamic and segmental stability, is one of the major goals in the management of patients with chronic low back pain (LBP. However, more investigation of lumbar stabilization training using a ball is required before making any strong conclusions about its efficacy. Objectives The aim of this study was to compare the effect of trunk stabilization exercises and conventional back care exercises for patients with chronic LBP. Patients and Methods Thirty male subjects with chronic LBP were randomly assigned to two groups. The experimental group received trunk stabilization exercise using a gym ball whereas the control group received conventional back care exercises for six weeks. The abdominal muscle endurance, pain intensity, and functional disability were measured using pressure biofeedback, visual analogue scale (VAS, and modified Oswestry disability questionnaire (MODQ, respectively. All the measurements were taken at baseline and during week two, four and six. Results The results of the study demonstrated significant improvements in abdominal muscle endurance and reduction in VAS and MODQ score of both groups (P = 0.001. The trunk stabilization exercise group showed greater gains in abdominal muscle endurance during weeks two to six compared to the conventional back care exercise group (P < 0.05. In addition, the trunk stabilization exercise group showed greater reduction in the VAS score (P = 0.035 and MODQ score (P = 0.001 at week six compared to the conventional back care exercise group. Conclusions The trunk stabilization exercises are more effective than conventional back care exercises in the rehabilitation of patients with chronic LBP.

  19. A COMPARITIVE STUDY TO KNOW THE EFFECTIVENESS OF PRONE BACK EXTENSION EXRECISES AND SWISS BALL EXERCISES ON BACK EXTENSOR MUSCLES PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Subhanjan Das

    2016-08-01

    Full Text Available Background: Endurance of the back muscles is important for stability of the trunk and therefore essential for normal functioning of an individual. Prone back extension exercises are traditional measures to improve back endurance. More recently Swiss ball exercises have become popular as a means to improve back endurance. Purpose of this study is to compare Prone back extension exercises with back extension exercise on Swiss ball on the improvement of the back extensor muscles performance, and thereby to find out which one is more appropriate for the prevention of back pain resulting from low extensor endurance. Back endurance can be measured by Bierring Sorensen endurance test. A low Sorensen score indicates low back endurance, which is associated with incidence of back pain. Methods: This study included 60 undergraduate students aged 18 to 23 years. The subjects were randomly divided into 2 equal groups. Pretest assessment was done by measurement of endurance of back extensors using Sorensen test. One group was given a series of prone back extension exercises on floor consisting of 5 levels. The second group was given a series of 5 exercises on Swiss ball. Each subject was assessed at the end of six weeks of intervention and after two weeks of finishing the regime (follow up to compare the effectiveness of Prone back extension exercises with Swiss ball exercises. Results: The results indicated that both the groups showed improvement in Sorensen score after 6 weeks of exercise. The average improvements of Prone back extension exercises and Swiss ball groups were 60.83 seconds and 66 seconds respectively. At two weeks follow up there is a slight change in the Sorensen score, with an average reduction of 1.34% and 0.95% for Prone back extension exercises and Swiss ball group respectively. However comparison of improvements in Sorensen score of Prone back extension exercises with Swiss ball exercises showed there is no significant difference

  20. SWISS BALL EXERCISE DAN KOREKSI POSTUR TDAK TERBUKTI LEBIH BAIK DALAM MEMPERKECIL DERAJAT SKOLIOSIS IDIOPHATIK DARIPADA KLAPP EXERCISE DAN KOREKSI POSTUR PADA ANAK USIA 11 – 13 TAHUN

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    Suriani Sari

    2013-11-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Scoliosis is abnormalities in skeletal form of the curvature of the spine , where the spine bending occurs towards the left or right side or abnormalities spine in the form of C or S. Common Signs of scoliosis include different shoulder bone , protruding shoulder blades , spine curvature real , pelvic tilt, the difference between arm and body space. Degree of scoliosis can be known with adam forward Bending and inclinometer test. The purpose of this study was to determine effectivity of swiss ball exercise training and posture correction and training effectiveness Klapp and posture correction exercise in reducing the scoliosis degree in children aged 11-13 years . This type of research was experimental design with pre and post contol group . In this study , 15 respondents were given swiss ball exercise training and 15 respondents were given Klapp excercise training . Each posture correction treatment was given every activity . Exercises performed with 45-minute frequency of 3 times a week for 12 weeks of data in the form of pre test and post test . Obtained by decreasing the degree of scoliosis. The results of this study are in the treatment group swiss ball exercise training the degree of scoliosis occurs with mean difference value of p < 0.05 and showed a significant difference . While in the commission of exercise training occurs Klapp mean difference degrees of scoliosis with a value of p < 0.05 and showed a significant difference. The conclusion of this study is the combination of swiss ball exercises and posture correction equally effective in reducing the degree of scoliosis with Klapp combination of exercise and posture correction in children aged 11-13 years. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso

  1. Differences in ball sports athletes speed discrimination skills before and after exercise induced fatigue.

    Science.gov (United States)

    Thomson, Kaivo; Watt, Anthony P; Liukkonen, Jarmo

    2009-01-01

    athletes to determine if they prioritize accuracy or speed of decision-making when physically exhausted.Speed discrimination stimuli were images of red square-shapes on a grey background presented moving along the sagittal axis at four different virtual velocities on a computer (PC) screen that represented the frontal plane.The participants exercised on a treadmill to level of 100% of peak oxygen uptake (VO2max).Repeated measures MANOVA revealed significant main effects for both the decision-making time and accuracy factors. The current findings clearly demonstrated that the athletes made decisions faster but with greater errors when fatigued.Post hoc analyses of the differences between the ball game sport groups indicated that soccer group participants reported a significantly lower number of errors than the basketball group (p = .015) in pre- and post-fatigue decision-making accuracy.Further investigations are required to clarify the equivocal set of previous findings regarding the relationship between the cognitive function of athletes at varying physical workload intensities.

  2. The effects of combination patterns of proprioceptive neuromuscular facilitation and ball exercise on pain and muscle activity of chronic low back pain patients.

    Science.gov (United States)

    Lee, Chae-Woo; Hwangbo, Kak; Lee, In-Sil

    2014-01-01

    [Purpose] The purpose of this study was to compare two methods for the muscle stabilization of the trunk of patients with chronic low back pain. The methods comprised combination patterns of proprioceptive neuromuscular facilitation (PNF) and ball exercise. [Subjects and Methods] The subjects were 40 volunteers who had low back pain. All subjects were randomly assigned to either a group which received proprioceptive neuromuscular facilitation or a group which performed ball exercise. Measurements were taken four times in total, at pre-intervention, two weeks later, four weeks later, and six weeks later. The main measurement methods used were the visual analogue scale (VAS) for pain and electromyography (EMG) for muscle activity. [Results] VAS and EMG activity were significantly reduced in the PNF combination pattern group and the ball exercise group. A comparison of the groups showed significant differences. In VAS and EMG activity; in particular, the combination pattern group using PNF increased EMG activity more than the ball exercise group did after six weeks of intervention. [Conclusion] This study showed that PNF combination pattern training for six weeks was more effective for patients with low back pain than performing ball exercise.

  3. Exercise in pregnant women and birth weight: a randomized controlled trial

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    Bø Kari

    2011-09-01

    Full Text Available Abstract Background Birth weight plays an important role in infant mortality and morbidity, childhood development, and adult health. To date there are contradictory results regarding the role of physical activity on birth weight. In addition, it is questioned whether exercise during second and third trimesters of pregnancy might affect gestational age and increase the risk of preterm delivery. Hence, the purpose of this study was to examine the effect of a supervised exercise-program on birth weight, gestational age at delivery and Apgar-score. Methods Sedentary, nulliparous pregnant women (N = 105, mean age 30.7 ± 4.0 years, pre-pregnancy BMI 23.8 ± 4.3 were randomized to either an exercise group (EG, n = 52 or a control group (CG, n = 53. The exercise program consisted of supervised aerobic dance and strength training for 60 minutes, twice per week for a minimum of 12 weeks, with an additional 30 minutes of self-imposed physical activity on the non-supervised week-days. Results There was no statistically significant difference between groups in mean birth weight, low birth weight ( Conclusion Aerobic-dance exercise was not associated with reduction in birth weight, preterm birth rate or neonatal well-being. Trial Registration ClinicalTrials.gov: NCT00617149

  4. Evaluating Abdominal and Lower-Back Muscle Activity While Performing Core Exercises on a Stability Ball and a Dynamic Office Chair.

    Science.gov (United States)

    Holmes, Michael W R; De Carvalho, Diana E; Karakolis, Thomas; Callaghan, Jack P

    2015-11-01

    The purpose of this study was to evaluate the ability of a dynamic office chair to activate the core muscles while participants performed exercises sitting on the chair compared to a stability ball. Prolonged sitting has become an accepted part of the modern office. However, epidemiological evidence suggests that sedentary postures are linked to many adverse effects on health. The concept of dynamic or active sitting is intended to promote movement while sitting to reduce the time spent in prolonged, static postures. Sixteen participants performed four pelvic rotation exercises (front-back, side-side, circular, and leg lift) on both a dynamic office chair and a stability ball. Muscle activity from 12 torso muscles were evaluated with surface electromyography. For all exercises, trunk muscle activity on the chair was comparable to that on a stability ball. The right external oblique was the only muscle to produce greater peak activity (p = .019) when using the ball compared to the chair (21.4 ± 14.0 percent maximal voluntary excitations (%MVE) and 14.7 ± 10.8 %MVE for the ball and chair, respectively). The left thoracic erector spinae produced greater average activity (p = .044) on the chair than on the ball. These findings suggest that this dynamic sitting approach could be an effective tool for core muscle activation while promoting movement and exercise while sitting at work. Muscle activations on the dynamic chair are comparable to those on a stability ball, and dynamic office chairs can promote movement and exercise while sitting at work. © 2015, Human Factors and Ergonomics Society.

  5. Mouth Breathing Syndrome: cervical muscles recruitment during nasal inspiration before and after respiratory and postural exercises on Swiss Ball.

    Science.gov (United States)

    Corrêa, Eliane C R; Bérzin, Fausto

    2008-09-01

    This study aimed to evaluate the recruitment of cervical muscles during nasal inspiration before and after breathing and postural exercises on the Swiss Ball in children with Mouth Breathing Syndrome (MBS). Surface electromyography from the sternocleidomastoid (SCM), sub-occipitals and upper Trapezius muscles was recorded during nasal inspiration, before and at the end of three months of the treatment. A physical therapy program consisting in muscular stretching and strengthening exercises along with naso-diaphragmatic breathing on the Swiss Ball were carried out for body posture realignment and respiratory training. Nineteen mouth breathing children, mean age of 10.6 years, both genres, were the subjects of this study. In order to establish a comparison between the eletromyographic results (normalized values) obtained from pre and post-physical therapy program it was used the Wilcoxon non-parametric test for dependent data. It was found a significant decrease (pinspiration in all tested muscles after treatment (11.3-3.6% in the SCM, 22.4-11.7% in the sub-occipitals and 8.9-3.1% in the upper Trapezius). At the end of the treatment, the assessed muscles reached lower activity electromyographic levels during nasal inspiration and they became closer of those in the quiet position. The lower activity after the physical therapy program in these muscles indicates a less effort of the accessory inspiratory muscles, probably due to a better performance of diaphragm muscle with the improvement of the body posture.

  6. Effect of birth weight and 12 weeks of exercise training on exercise-induced AMPK signaling in human skeletal muscle

    DEFF Research Database (Denmark)

    Mortensen, Brynjulf; Hingst, Janne Rasmuss; Frederiksen, Nicklas

    2013-01-01

    Subjects with a low birth weight (LBW) display increased risk of developing type 2 diabetes (T2D). We hypothesized that this is associated with defects in muscle adaptations following acute and regular physical activity, evident by impairments in the exercise-induced activation of AMPK signaling....... the need for AMPK to control energy turnover during exercise. Thus, the remaining ¿3-associated AMPK activation by acute exercise after exercise training might be sufficient to maintain cellular energy balance........ We investigated 21 LBW and 21 normal birth weight (NBW) subjects during 1 hour of acute exercise performed at the same relative workload before and after 12 weeks of exercise training. Multiple skeletal muscle biopsies were obtained before and after exercise. Protein levels and phosphorylation status...... were determined by Western blotting. AMPK activities were measured using activity assays. Protein levels of AMPK isoforms a1 and ¿1 were significantly increased while ¿3 levels decreased with training independent of group. The LBW group had higher exercise-induced AMPK Thr(172) phosphorylation before...

  7. Distribution and predictors of exercise habits among pregnant women in the Danish National Birth Cohort

    DEFF Research Database (Denmark)

    Juhl, M.; Madsen, M.; Andersen, A. M. N.

    2012-01-01

    Physical activity is recommended during pregnancy, although strong evidence on reproductive health is lacking. We present exercise habits and predictors of exercise during pregnancy. From the Danish National Birth Cohort (1996-2002), 88 200 singleton pregnancies were analyzed in logistic regression....... About one-third of the women exercised in early/mid pregnancy and slightly less in late pregnancy. Bicycling, swimming, and low-impact activities were most common. Exercising more than three times per week was strongly correlated with older age, being a student or out of work, eating disorders, moderate...

  8. Effects of Hemibridge with Ball and Balloon Exercise on Forced Expiratory Volume and Pain in Patients with Chronic Low Back Pain: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Jorida Fernandes

    2017-08-01

    Full Text Available Background and objectives: Suboptimal breathing patterns and impairments of posture and trunk stability are often associated with musculoskeletal complaints such as low back pain. Respiration is also affected by poor neuromuscular control of core muscles. Immediate effects of hemibridge with ball and balloon exercise has been studied on chronic pain in athlete population. Objective: To evaluate the effects of hemibridge with ball and balloon exercise on pain, forced expiratory volume and functional abilities in patients with chronic low back pain using Visual Analogue Scale (VAS, Forced Expiratory Volume (FEV and Modified Oswestry Disability Questionnaire (MODQ. Methods: The present experimental study was conducted among 30 participants between the age of 21 to 55 years with chronic non-specific LBP. The participants were given a hemibridge with ball and balloon exercise. Pre-interventional and 3rd day Post-interventional outcome measurements were taken using VAS, FEV1 and FEV6 and MODQ. Results: The difference between pre-and post of VAS was statistically highly significant (p=0.0001. The p value of FEV6 and MODQ by paired t test was statistically significant with p value of 0.02 and 0.0007 respectively. Conclusion: The study concludes that there is an immediate effect of hemibridge with ball and balloon exercise on pain, FEV6 and functional ability in patients with chronic LBP.

  9. Comparison the effects of two types of therapeutic exercises Frenkele vs. Swiss ball on the clinical balance measures in patients with type II diabetic neuropathy.

    Science.gov (United States)

    Rojhani-Shirazi, Zahra; Barzintaj, Fatemeh; Salimifard, Mohamad Reza

    2017-11-01

    The number of diabetic patients is increasing in the world. Peripheral neuropathy is the most important problem of diabetes. Neuropathy eventually leads to balance impairment which is the main cause of falling down in these patients However, not sufficient evidences available to compare different protocols for improving balance in diabetic patients. This study aimed to compare the effects of two therapeutic exercises on clinical balance measures in patients with type II diabetic peripheral neuropathy. The study was performed on 60 patients with diabetes categorized randomly into three groups: an intervention group (N=20) that received ball training exercise, another intervention group (N=20) that received Frenkel exercise and a control group (N=20) that received no interventions. Exercise training session was performed for 3 weeks. Then, clinical balance measures were computed in the three groups. Paired t-test and one-way ANOVA were used to analyze the collected data. Both types of therapeutic exercise programs significantly improved balance in single leg stance, star excursion test, and Berg balance scale test (P˂0.05) compared to the control group. Besides, this was more significant in the ball training group (P˂0.05). To improve balance in diabetic neuropathy, Swiss ball exercise is preferred compared to Frenkel training. Copyright © 2016. Published by Elsevier Ltd.

  10. Exercise-Based Interventions for Injury Prevention in Tackle Collision Ball Sports: A Systematic Review.

    Science.gov (United States)

    Sewry, Nicola; Verhagen, Evert; Lambert, Mike; van Mechelen, Willem; Viljoen, Wayne; Readhead, Clint; Brown, James

    2017-09-01

    The injury burden in collision sports is relatively high compared to other team sports. Therefore, participants in these sports would benefit by having effective injury prevention programs. Exercise-based interventions have successfully reduced injuries in soccer, but evidence on exercise-based interventions in tackle collision sports is limited. The objective of this review is to systematically examine the evidence of exercise-based intervention programs reducing injuries in tackle collision sports. PubMed, EBSCOHost, and Web of Science were searched for articles published between January 1995 and December 2015. The methodological quality was assessed using an adapted Cochrane Bone Joint and Muscle Trauma Group quality assessment tool. The inclusion criteria were (1) (randomized) control trials and observational studies; (2) sporting codes: American, Australian and Gaelic Football, rugby union, and rugby league; (3) participants of any age or sex; (4) exercise-based, prehabilitative intervention; and (5) primary outcome was injury rate or incidence (injury risk). The exclusion criteria were (1) unavailability of full-text; and (2) article unavailable in English. Nine studies with a total of 3517 participants were included in this review. Seven of these studies showed a significant decrease in injury risk. These studies included three sporting codes and various age groups, making it difficult to make inferences. The two highest methodological quality studies found no effect of an exercise-based intervention on injury risk. There is evidence that exercise-based injury preventions can be beneficial in reducing injury risk in collision sports, but more studies of high methodological quality are required.

  11. A RANDOMISED CONTROLLED STUDY ON CORE STABILITY EXERCISE PROGRAMME USING SWISS BALL, THERABAND AND FLOOR EXERCISES IN CRICKETERS WITH LOW BACK PAIN

    Directory of Open Access Journals (Sweden)

    M.Seshagirirao

    2015-12-01

    Full Text Available Background: Low back pain is one of the common complaints seen in cricketers. Core stability is defined as the ability to control the position and motion of the trunk over the pelvis to allow optimum production, transfer and control of force and motion to the terminal segment in integrated athletic activities and generally given as treatment in many instances. No randomized controlled studies were there for low back pain in cricketers. So, purpose of this study was to know the efficacy of Swiss ball(SB, Thera-band(TB, and Floor exercises(FE in cricketers with low back pain. Methods: Sixty male competitive cricket players between 15-35 years age were randomly assigned into 4 groups. SB (n=15, TB (n=15, FE (n=15, control group (n=15. Analysis of data within group and between groups of the pre and post treatment values of pain-disability(Modified Oswestry Low Back Pain Questionnaire and core strength(double-leg lowering test was done statistically using t test and ANOVA test. Results: The results of within group analysis, showed extremely significant improvement in terms of pain & disability and back strength (p<0.0001 in all the groups, whereas in between groups, TB(theraband group showed significant improvement compared to SB(swissball, FE(floor-exercise and control groups. Conclusion: The results revealed that Thera-band (TB group had better improvement than the other three groups in decreasing low back pain and improving core stability.

  12. DIFFERENCES IN BALL SPORTS ATHLETES SPEED DISCRIMINATION SKILLS BEFORE AND AFTER EXERCISE INDUCED FATIGUE

    Directory of Open Access Journals (Sweden)

    Kaivo Thomson

    2009-06-01

    Full Text Available Substantial research exists in relation to the effect of fatigue on the cognitive skills of athletes. Very few studies in the sport domain, however, have investigated decision-making time and accuracy in relation to the discrimination of the speed of a moving object following exercise at maximal intensity. The purpose of this study was to examine differences in the pre- and post-fatigue speed discrimination skills of elite ballgames athletes to determine if they prioritize accuracy or speed of decision-making when physically exhausted. The participants in the study were 163 males (M = 21.17, SD = 4.18 Estonian national level soccer (n = 79, basketball (n = 63 and volleyball (n = 21 players. Peak oxygen uptake (VO2max was assessed during completion of an incremental exercise test on a treadmill. Speed discrimination stimuli were images of red square-shapes on a grey background presented moving along the sagittal axis at four different virtual velocities on a computer (PC screen. Repeated measures MANOVA revealed a significant main effect for the decision-making time factor. A second MANOVA revealed a significant main effect for the decision-making accuracy factor. The soccer group made a significantly lower number of errors than the basketball group (p = 0.015 in pre- and post-fatigue decision-making accuracy. The results showed that athletes' decision-making time decreased and decision-making errors increased after a maximal aerobic capacity exercise task. A comparison of the pre- and post-fatigue speed discrimination skills of experienced basketball, volleyball and soccer players indicated that the only significant difference was for decision-making accuracy between the soccer and basketball groups. The current findings clearly demonstrated that the athletes made decisions faster at the expense of accuracy when fatigued

  13. The implementation of musculoskeletal injury-prevention exercise programmes in team ball sports: a systematic review employing the RE-AIM framework.

    Science.gov (United States)

    O'Brien, James; Finch, Caroline F

    2014-09-01

    Team ball sports such as soccer, basketball and volleyball have high participation levels worldwide. Musculoskeletal injuries are common in team ball sports and are associated with significant treatment costs, participation loss and long-term negative side effects. The results of recent randomized controlled trials provide support for the protective effect of injury-prevention exercise programmes (IPEPs) in team ball sports, but also highlight that achieving adequate compliance can be challenging. A key process in enhancing the ultimate impact of team ball sport IPEPs is identifying the specific implementation components that influence the adoption, execution and maintenance of these interventions. Despite this, no systematic review focussing on the specific implementation components of team ball sport IPEPs has been conducted. Our objective was to assess the reporting of specific implementation components in the published literature on team ball sport IPEPs using the Reach Efficacy Adoption Implementation Maintenance (RE-AIM) framework. Six electronic databases were systematically searched from inception to December 2012 for papers reporting team ball sport IPEP trials. All eligible papers were independently evaluated by two raters before reaching consensus on the reporting of individual RE-AIM items, using the RE-AIM Model Dimension Items Checklist (RE-AIM MDIC). A total of 60 papers, reporting 52 unique intervention trials, met eligibility criteria. Before consensus, the level of agreement across all trials between reviewers using the RE-AIM MDIC ranged from 81 to 91%. The RE-AIM MDIC dimension of 'efficacy' had the highest level of reporting, with the five individual items in this dimension reported in 19-100% of eligible trials (mean 58%). The RE-AIM MDIC dimension 'maintenance-setting level' had the lowest level of reporting, with none of the four individual items in this dimension reported. For other dimensions, the mean level of reporting and range across

  14. Physical exercise during pregnancy and fetal growth measures: a study within the Danish National Birth Cohort

    DEFF Research Database (Denmark)

    Juhl, Mette; Olsen, Jørn; Andersen, Per Kragh

    2010-01-01

    OBJECTIVE: The objective of the study was to examine the association between physical exercise during pregnancy and fetal growth measures. STUDY DESIGN: Data on 79,692 liveborn singletons from the Danish National Birth Cohort were collected between 1996 and 2002. Mean differences in birthweight...... effects on fetal growth measures related to exercise apart from a modest decreased risk of small- and large-for-gestational-age infants. These findings do not speak against advising pregnant women to be physically active during pregnancy......., length, ponderal index, head and abdominal circumference, and placental weight and hazard ratios of small- and large-for-gestational-age babies were calculated. RESULTS: Our data indicated smaller babies in exercising women compared with nonexercisers, but the differences were small, and only a few were...

  15. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  16. Aerobic exercise, ball sports, dancing, and weight lifting as moderators of the relationship between stress and depressive symptoms: an exploratory cross-sectional study with swiss university students.

    Science.gov (United States)

    Gerber, Markus; Brand, Serge; Elliot, Catherine; Holsboer-Trachsler, Edith; Pühse, Uwe

    2014-12-01

    This exploratory study was designed to compare four types of exercise activities in Swiss university students. A sample of 201 medical students (136 women, 65 men; M age = 23.2 yr., SD = 2.4) and 250 exercise and health sciences students (144 women, 106 men; M age = 22.3 yr., SD = 2.2) participated in the study. They completed the Perceived Stress Scale, the Depression Scale, and the Office in Motion Questionnaire. Interaction effects between stress and exercise activities were analysed using hierarchical regression analyses, after controlling for age, sex, and academic discipline. Frequent participation in ball sports and dancing were associated with decreased depressive symptoms among students with elevated perceived stress, whereas no such relationship existed among their peers with lower perceived stress. No stress-moderating effect was found for aerobic exercise. Weight lifting was only associated with lower depressive symptoms among students with low perceived stress. The present findings suggest that, among Swiss university students, certain exercises may have better potential to moderate the relationship between perceived stress and depressive symptoms than others. Future research could analyze whether personalized exercise programs created to satisfy participants' individual needs are more beneficial for stress management.

  17. Comparison of physio ball and plinth trunk exercises regimens on trunk control and functional balance in patients with acute stroke: a pilot randomized controlled trial.

    Science.gov (United States)

    Karthikbabu, S; Nayak, Akshatha; Vijayakumar, K; Misri, Zk; Suresh, Bv; Ganesan, Sailakshmi; Joshua, Abraham M

    2011-08-01

    To examine the effects of trunk exercises performed using the physio ball as against the plinth, on trunk control and functional balance in patients with acute stroke. An observer-blinded pilot randomized controlled trial. Thirty patients with acute stroke (mean post-stroke duration 12 (95% confidence interval (CI) 2-34) days) who had the first onset of unilateral haemorrhagic or ischaemic lesion and an independent ability to sit for 30 seconds. Inpatient stroke rehabilitation centre. The experimental group performed task-specific trunk exercises on an unstable surface (physio ball) while the control group performed them on a stable surface (plinth). In addition to regular acute physiotherapy, both the groups underwent 1 hour of trunk exercises a day, four days a week for three weeks. Trunk Impairment Scale and Brunel Balance Assessment. The difference between the baseline characteristics of the patients belonging to both groups was not statistically significant. Post-intervention, both the groups improved on trunk control and functional balance but the experimental group improved more significantly than the control group (change scores of between-group comparison for the total Trunk Impairment Scale 3.06 (1.43), dynamic sitting balance 1.47 (1.36) and coordination 1.3 (0.67) subscales of Trunk Impairment Scale; the total Brunel Balance Assessment 1.8 (1.4) and stepping 1.87 (1.6) component of Brunel Balance Assessment). The level of significance was set at P physio ball are more effective than those performed on the plinth in improving both trunk control and functional balance in acute stroke patients, suggesting a task-specific effect and also a carry-over effect.

  18. The short-term effects of trigger point therapy, stretching and medicine ball exercises on accuracy and back swing hip turn in elite, male golfers - A randomised controlled trial.

    Science.gov (United States)

    Quinn, Samantha-Lynn; Olivier, Benita; Wood, Wendy-Ann

    2016-11-01

    This study aimed to compare the effect of myofascial trigger point therapy (MTPT) and stretching, MTPT and medicine ball exercises, and no intervention, on hip flexor length (HFL), golf swing biomechanics and performance in elite, male golfers. Single blind, randomised controlled trial with two experimental groups (stretch group: MTPT and stretching; and the ball group: MTPT, a single stretch and medicine ball exercises) and one control group (no intervention). Professional golf academy. One hundred, elite, male golfers aged 16-25 years. HFL, 3D biomechanical analysis of the golf swing, club head speed (CHS), smash ratio, accuracy and distance at baseline and after the interventions. Backswing hip turn (BSHT) improved in the ball group relative to the control group (p = 0.0248). Accuracy in the ball group and the stretch group improved relative to the control group (Fisher's exact = 0.016). Other performance parameters such as: smash ratio, distance and CHS were not compromised by either intervention. This study advocates the use of MTPT combined with medicine ball exercises over MTPT combined with stretching in the treatment of golfers with shortened hip flexors - even immediately preceding a tournament. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Ball clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

    The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

  20. Prevention: Exercise

    Medline Plus

    Full Text Available ... and toes turned in very slightly. Hold a ball directly in front of you. Keep your abdominal ... if you are able to use progressively heavier balls, you will experience more benefit from this exercise... ...

  1. Ball lightning.

    OpenAIRE

    Stenhoff, Mark

    1988-01-01

    Ball lightning is alleged by some to be a rare atmospheric phenomenon usually associated with thunderstorms, while others hold that it does not exist. This controversy has continued for centuries. This study comprises a critical evaluation of evidence for the existence of ball lightning. An historical review of the controversy is first presented, giving a chronological account of developments in ball lightning theories and of important observations alleged to be of the phenomenon. Other pheno...

  2. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

  3. Ball game popularity

    OpenAIRE

    Gregorič, Vanja

    2011-01-01

    In the diploma thesis I present ball games and how they are popular among children of 4th and 5th form of primary school. Sport activities play an important role when growing up and it is up to adults to provide children a certain amount of exercise in the pre-school period and during their schooling. It is important that one considers child's age and that the activities are represented through playing. Ball games are included in the curriculum in one of the sets in the first three years. In ...

  4. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2013-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  5. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

    The Table of Contents for the full book PDF is as follows: * Organizing Committee * Preface * Ball Lightning -- The Continuing Challenge * Hungarian Ball Lightning Observations in 1987 * Nature of Ball Lightning in Japan * Phenomenological and Psychological Analysis of 150 Austrian Ball Lightning Reports * Physical Problems and Physical Properties of Ball Lightning * Statistical Analysis of the Ball Lightning Properties * A Fluid-Dynamical Model for Ball Lightning and Bead Lightning * The Lifetime of Hill's Vortex * Electrical and Radiative Properties of Ball Lightning * The Candle Flame as a Model of Ball Lightning * A Model for Ball Lightning * The High-Temperature Physico-Chemical Processes in the Lightning Storm Atmosphere (A Physico-Chemical Model of Ball Lightning) * New Approach to Ball Lightning * A Calculation of Electric Field of Ball Lightning * The Physical Explanation to the UFO over Xinjiang, Northern West China * Electric Reconnection, Critical Ionization Velocity, Ponderomotive Force, and Their Applications to Triggered and Ball Lightning * The PLASMAK™ Configuration and Ball Lightning * Experimental Research on Ball Lightning * Performance of High-Voltage Test Facility Designed for Investigation of Ball Lightning * List of Participants

  6. Evaluation of a birth preparation program on lumbopelvic pain, urinary incontinence, anxiety and exercise: a randomized controlled trial.

    Science.gov (United States)

    Miquelutti, Maria Amélia; Cecatti, José Guilherme; Makuch, Maria Yolanda

    2013-07-29

    Antenatal preparation programmes are recommended worldwide to promote a healthy pregnancy and greater autonomy during labor and delivery, prevent physical discomfort and high levels of anxiety. The objective of this study was to evaluate effectiveness and safety of a birth preparation programme to minimize lumbopelvic pain, urinary incontinence, anxiety, and increase physical activity during pregnancy as well as to compare its effects on perinatal outcomes comparing two groups of nulliparous women. A randomized controlled trial was conducted with 197 low risk nulliparous women aged 16 to 40 years, with gestational age ≥ 18 weeks. Participants were randomly allocated to participate in a birth preparation programme (BPP; n=97) or a control group (CG; n=100). The intervention was performed on the days of prenatal visits, and consisted of physical exercises, educational activities and instructions on exercises to be performed at home. The control group followed a routine of prenatal care. Primary outcomes were urinary incontinence, lumbopelvic pain, physical activity, and anxiety. Secondary outcomes were perinatal variables. The risk of urinary incontinence in BPP participants was significantly lower at 30 weeks of pregnancy (BPP 42.7%, CG 62.2%; relative risk [RR] 0.69; 95% confidence interval [CI] 0.51-0.93) and at 36 weeks of pregnancy (BPP 41.2%, CG 68.4%; RR 0.60; 95%CI 0.45-0.81). Participation in the BPP encouraged women to exercise during pregnancy (p=0.009). No difference was found between the groups regarding to anxiety level, lumbopelvic pain, type or duration of delivery and weight or vitality of the newborn infant. The BPP was effective in controlling urinary incontinence and to encourage the women to exercise during pregnancy with no adverse effects to pregnant women or the fetuses. Clinicaltrials.gov, (NCT01155804).

  7. Prevention: Exercise

    Medline Plus

    Full Text Available ... and toes turned in very slightly. Hold a ball directly in front of you. Keep your abdominal muscles tight and feet flat on the floor; rotate from side to side. Repeat 10 times. Check with your ... balls, you will experience more benefit from this exercise... ...

  8. Ban Deodorant Ball Mortar.

    Science.gov (United States)

    Carpenter, D. Rae, Jr.; And Others

    1988-01-01

    Discusses a demonstration of vertical collision of two balls. Shows the theoretical height ratio using mathematical expression and diagrams. Compares it with researchers' experimental results. Expands the two-ball collision to multi-ball system. (YP)

  9. Prevention: Exercise

    Medline Plus

    Full Text Available ... Exercise Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain Preventing Osteoporosis Back ... in very slightly. Hold a ball directly in front of you. Keep your abdominal muscles tight and ...

  10. Prevention: Exercise

    Medline Plus

    Full Text Available ... support for your body. Pilates, yoga and martial arts all provide well-rounded core strengthening programs. Simple ... use progressively heavier balls, you will experience more benefit from this exercise... Sagittal Core Strengthening You can ...

  11. FOUR BALL BEST BALL 1

    Directory of Open Access Journals (Sweden)

    Geoff Pollard

    2010-03-01

    Full Text Available In this paper a four-ball-best-ball (4BBB model for pairs of golf players is set up. The 4BBB match-play scoring system is seen to satisfy a basic requirement of fairness. It is shown that it is not strictly possible to rate individual players as 4BBB players. However, a (reasonably broad class of individual players is identified such that it is possible to rate them individually as 4BBB players. The capacity of an individual to play birdies is seen to be a very important determinant in being a successful member of a 4BBB pair, but there are other minor factors as well. Consideration is given to equal and unequal 4BBB pairs. The transitive law is seen to apply for 4BBB pairs. Thus, if pair A is better than pair B, and pair B is better than pair C, then pair A must be better than pair C. Correspondingly, if pair A is equal to pair B, and pair B is equal to pair C, then pair A is equal to pair C. Consideration is given to some strategic issues in 4BBB match-play golf. For example, the conditions under which a player should take a greater risk and have a higher probability of obtaining a bogie in order to achieve a higher probability of scoring a birdie, are determined. Also, the conditions under which a player, noting that his partner is about to have a ‘bad’ hole and score only a par or a bogie, should ‘play safe’, are determined. Thirdly, players who can interact in certain ways are seen to have an advantage over those pairs that cannot do this. Finally, one pair’s optimal strategy when they see that their opponents are about to score a par or a bogie, but not a birdie, is analyzed

  12. The Effect of Assisted Exercise Frequency on Bone Strength in Very Low Birth Weight Preterm Infants: A Randomized Control Trial.

    Science.gov (United States)

    Litmanovitz, Ita; Erez, Hedva; Eliakim, Alon; Bauer-Rusek, Sofia; Arnon, Shmuel; Regev, Rivka H; Sirota, Gisela; Nemet, Dan

    2016-09-01

    We aimed to assess whether a twice daily assisted exercise interventional program will have a greater effect on bone strength compared to a once daily intervention or no intervention in very low birth weight (VLBW) preterm infants. Thirty-four very VLBW preterm infants (mean BW 1217 ± 55 g and mean gestational age 28.6 ± 1.1 weeks) were randomly assigned into one of three study groups: twice daily interventions (n = 13), a once daily intervention (n = 11), and no intervention (control, n = 10). The intervention was initiated at a mean of 8 ± 2.4 days of life and continued for 4 weeks. It included passive extension and flexion range-of-motion exercise of the upper and lower extremities. Bone strength was measured at enrollment and after 2 and 4 weeks using quantitative ultrasound of tibial bone speed of sound (SOS, Sunlight Omnisense™). At enrollment, the mean bone SOS was comparable between the twice daily interventions, once daily intervention and control groups (2918 ± 78, 2943 ± 119, and 2910 ± 48 m/s, respectively). As expected, the bone SOS declined in all groups during the study period (-23.6 ± 24, -68.8 ± 28, and -115.8 ± 30 m/s, respectively, p strength in the twice daily intervention group (p = 0.03). A twice daily intervention program of assisted range-of-motion exercise attenuates the decrease in bone strength and may decrease the risk of osteopenia and future fractures in VLBW preterm infants.

  13. Relación entre la fuerza máxima en squat y acciones de salto, sprint y golpeo de balón. (Relationship among maximal strength in squat exercise, jump, sprint and kicking ball performance.

    Directory of Open Access Journals (Sweden)

    Alfredo Arija Blázquez

    2008-01-01

    Full Text Available ResumenEl objetivo del presente estudio fue analizar las posibles relaciones entre la fuerza máxima en squat y accionesexplosivas de salto, sprint y golpeo de balón. Para ello, se contó con una muestra formada por estudiantes de Ciencias del Deporte (N= 16; 19,6 ± 1,7 años de sexo masculino (con escasa experiencia en el entrenamiento de fuerza, que llevaron a cabo un test de 1RM en squat (calculándose el peso levantado, la fuerza media total y la fuerza dinámica máxima, tests de salto vertical (SJ, CMJ y CMJa, un test de sprint de 20 m (con mediciones de tiempo cada 5 m, y un test de golpeo con el pie donde se calculaba la velocidad del balón. Se encontraron coeficientes de correlación moderados (entre 0,52 y 0,67 y significativos de las medidas de fuerza máxima y las alturas de salto, mientras que los coeficientes obtenidos entre los tiempos de sprint y dichas medidas de fuerza máxima se situaron entre -0,06 y -0,32, no siendo ninguno de ellos significativo; al igual que tampoco fueron significativos los coeficientes de correlación de las medidas de fuerza máxima y la velocidad de tiro, se situaron entre 0,25 y 0,34. Por tanto, la relación entre la fuerza máxima en squat y la altura de salto en sujetos con escasa experiencia en el entrenamiento de fuerza resultó moderada, mientras que no parece existir relación con el tiempo de sprint y la velocidad de tiro.AbstractThe purpose of the present study was to analyze the possible relationships between maximal strength insquat exercise and jump, sprint and kicking ball actions. Sixteen males sport science students (19,6 ± 1,7years, with little experience in strength training, performed a 1RM in squat exercise (from which liftedweight, the total average- and maximal-dynamic strength was assessed, vertical jump (SJ, CMJ and CMJa, a 20 m sprint test (with time measurement every 5 m, and a kicking ball test where the velocity of the ball was calculated. Moderate (0,52 - 0,67 and

  14. Prevention: Exercise

    Medline Plus

    Full Text Available ... be done at home as well. Some specific core strengthening exercises are described below. If any of the following ... balls, you will experience more benefit from this exercise... Sagittal Core Strengthening You can stretch and strengthen the low back ...

  15. Prevention: Exercise

    Medline Plus

    Full Text Available ... be done at home as well. Some specific core strengthening exercises are described below. If any of the following ... balls, you will experience more benefit from this exercise... Sagittal Core Strengthening You can stretch and strengthen the low ...

  16. Having a Ball with Fitness Balls

    Science.gov (United States)

    McNulty, Betty

    2011-01-01

    Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

  17. The Goldenrod Ball Gall

    Science.gov (United States)

    Fischer, Richard B.

    1974-01-01

    The paper presents a generalized life history of the goldenrod ball gall, a ball-shaped swelling found almost exclusively on the Canada goldenrod, Solidago canadensis, and caused by a peacock fly know as Eurosta soldiaginis. (KM)

  18. Ball Screw Actuator Including a Compliant Ball Screw Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2017-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  19. Exercises

    Science.gov (United States)

    ... Departments Clinical Research & Science Education & Training Home Conditions Chronic Obstructive Pulmonary Disease (COPD) COPD: Overview COPD: Lifestyle Management COPD: Exercises COPD: Exercises Make an Appointment Refer a Patient Ask a Question Reviewed by Barry J. Make, ...

  20. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  1. The spinning ball spiral

    Science.gov (United States)

    Dupeux, Guillaume; Le Goff, Anne; Quéré, David; Clanet, Christophe

    2010-09-01

    We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.

  2. Great balls of fire

    Science.gov (United States)

    Stenhoff, Mark; reader01; jjherrera

    2014-03-01

    In reply to the physicsworld.com news article “Burning soil fuels ball lightning” (9 January, http://ow.ly/tl8aO) on evidence that a burning core of soil acts as an energy source for ball lightning.

  3. Ball Collision Experiments

    Science.gov (United States)

    Cross, R.

    2015-01-01

    Experiments are described on collisions between two billiard balls and between a bat and a ball. The experiments are designed to extend a student's understanding of collision events and could be used either as a classroom demonstration or for a student project.

  4. Punjab Ball Menu

    OpenAIRE

    Hobday, E, fl. 1905, artist

    2003-01-01

    A photograph of the exterior of a menu from the 'Punjab Ball'. The menu is decorated on both the inside and outside with illustrations by 'E. Hobday'. Inside the menu, in pen, is written: 'Lahore, Ball in Montgomery Hall, Nov 30th. 1905'.

  5. Happy Balls, Unhappy Balls, and Newton's Cradle

    Science.gov (United States)

    Kagan, David

    2010-01-01

    The intricacies of Newton's Cradle are well covered in the literature going as far back as the time of Newton! These discussions generally center on the highly elastic collisions of metal spheres. Thanks to the invention of happy and unhappy balls, you can build and study the interaction of less elastic systems (see Fig. 1).

  6. Compact Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Losano, L.; Marques, M.A. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Menezes, R. [Departamento de Ciências Exatas, Universidade Federal da Paraíba, 58297-000 Rio Tinto, PB (Brazil); Departamento de Física, Universidade Federal de Campina Grande, 58109-970 Campina Grande, PB (Brazil); Rocha, R. da [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, 09210-580 Santo André (Brazil)

    2016-07-10

    In this work we deal with non-topological solutions of the Q-ball type in two space–time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  7. Exercise

    DEFF Research Database (Denmark)

    Idorn, Manja; thor Straten, Eivind Per

    2016-01-01

    We recently demonstrated that voluntary exercise leads to an influx of immune cells in tumors and a greater than 60% reduction in tumor incidence and growth across several mouse models. Improved immunological control of tumor progression may have important clinical implications in the prevention...

  8. Formation of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Silberg, P.A. (2833 Lawton Drive, Amarillo, Texas (USA))

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which under certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma.

  9. Fiber ball imaging.

    Science.gov (United States)

    Jensen, Jens H; Russell Glenn, G; Helpern, Joseph A

    2016-01-01

    By modeling axons as thin cylinders, it is shown that the inverse Funk transform of the diffusion MRI (dMRI) signal intensity obtained on a spherical shell in q-space gives an estimate for a fiber orientation density function (fODF), where the accuracy improves with increasing b-value provided the signal-to-noise ratio is sufficient. The method is similar to q-ball imaging, except that the Funk transform of q-ball imaging is replaced by its inverse. We call this new approach fiber ball imaging. The fiber ball method is demonstrated for healthy human brain, and fODF estimates are compared to diffusion orientation distribution function (dODF) approximations obtained with q-ball imaging. The fODFs are seen to have sharper features than the dODFs, reflecting an enhancement of the higher degree angular frequencies. The inverse Funk transform of the dMRI signal intensity data provides a simple and direct method of estimating a fODF. In addition, fiber ball imaging leads to an estimate for the ratio of the fraction of MRI visible water confined to the intra-axonal space divided by the square root of the intra-axonal diffusivity. This technique may be useful for white matter fiber tractography, as well as other types of microstructural modeling of brain tissue. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Do changing levels of maternal exercise during pregnancy affect neonatal adiposity? Secondary analysis of the babies after SCOPE: evaluating the longitudinal impact using neurological and nutritional endpoints (BASELINE) birth cohort (Cork, Ireland)

    Science.gov (United States)

    Norris, Tom; McCarthy, Fergus P; Khashan, Ali S; Murray, Deidre M; Kiely, Mairead; Hourihane, Jonathan O’B; Baker, Philip N; Kenny, Louise C

    2017-01-01

    Objective To investigate whether changing levels of exercise during pregnancy are related to altered neonatal adiposity. Design Secondary analysis of data from a prospective cohort study. Setting Cork, Ireland. Participants 1200 mother–infant pairs recruited as part of a prospective birth cohort, Babies After SCOPE: Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints (BASELINE). Main outcome measures Neonatal adiposity was assessed within several days of birth using air displacement plethysmography (PEAPOD). Per cent body fat (BF%) as a continuous outcome and a pair of dichotomous variables; high or low adiposity, representing BF% >90th or <10th centile, respectively. Multivariable linear and logistic regression models were used to investigate the relationship between exercise and the respective outcomes. Results Crude analysis revealed no association between a changing level of exercise (since becoming pregnant) at 15 weeks’ gestation and any of the outcomes (BF%, low adiposity and high adiposity). At 20 weeks’ gestation, analyses revealed that relative to women who do not change their exercise level up to 20 weeks, those women who decreased their exercise level were more likely to give birth to a neonate with adiposity above the 90th centile (OR 1.62, 95% CI 1.07 to 2.46). This association was maintained after adjustment for putative confounders (OR 1.62, 95% CI 1.06 to 2.47). Conclusions We observed a possible critical period for the association between changing exercise levels and neonatal adiposity, with no association observed with exercise recall for the first 15 weeks of gestation, but an association with a decreasing level of exercise between 15 and 20 weeks. These results should be interpreted in line with the limitations of the study and further studies utilising objectively measured estimates of exercise are required in order to replicate these findings. Trial registration number NCT01498965. PMID:29196482

  11. Ball lightning burn.

    Science.gov (United States)

    Selvaggi, Gennaro; Monstrey, Stan; von Heimburg, Dennis; Hamdi, Mustapha; Van Landuyt, Koen; Blondeel, Phillip

    2003-05-01

    Ball lightning is a rare physical phenomenon, which is not yet completely explained. It is similar to lightning but with different, peculiar characteristics. It can be considered a mix of fire and electricity, concentrated in a fireball with a diameter of 20-cm that most commonly appears suddenly, even in indoor conditions, during a thunderstorm. It moves quickly for several meters, can change direction, and ultimately disappears. During a great storm, a 28-year-old man and his 5-year-old daughter sustained burn wounds after ball lightning came from the outdoors through a chimney. These two patients demonstrated signs of fire and electrical injuries. The father, who lost consciousness, sustained superficial second-degree burn wounds bilaterally on the zygomatic area and deep second-degree burn wounds on his right hand (total body surface area, 4%). His daughter demonstrated superficial second-degree burn wounds on the left part of the face and deep second-degree and third-degree burn wounds (total body surface area, 30%) on the left neck, both upper arms, and the back. In this article, the authors report the first two cases of burn injuries resulting from ball lightning contact indoors. The literature on this rare phenomenon is reviewed to elucidate the nature of ball lightning. Emphasis is placed on the nature of injuries after ball lightning contact, the therapy used, and the long-term complications.

  12. The bowling balls

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…   The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse. Almost 40 years ago, the web, Wikipedia and Google did not exist and it was much more difficult to know whether other people in other parts of the world or even in the same laboratory were facing the same problems or developing the same tools. At that time, Bent Stumpe was an electronics engineer, newly recruited to work on developments for the SPS Central Control room. One of the things his supervisor asked him to build as soon as possible was a device to control a pointer on a screen, also called a tracker ball. The heart of the device was the...

  13. Accuracy and Reliability of a New Tennis Ball Machine.

    Science.gov (United States)

    Brechbuhl, Cyril; Millet, Grégoire; Schmitt, Laurent

    2016-06-01

    The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min(-1). The initial frequency was 10 and increased by 2 until 22, then by 1 until 30 balls·min(-1). The reference points for the impact were 8.39m from the net and 2.70m from lateral line for the right side and 2.83m for the left side. The precision of the machine was similar on the right and left sides (0.63 ± 0.39 vs 0.63 ± 0.34 m). The distances to the reference point were 0.52 ± 0.42, 0.26 ± 0.19, 0.52 ± 0.37, 0.28 ± 0.19 m for the Y-right, X-right, Y-left and X-left impacts. The precision was constant and did not increase with the intensity. (e.g ball frequency). The ball velocity was 86.3 ± 1.5 and 86.5 ± 1.3 km·h(-1) for the right and the left side, respectively. The coefficient of variation for the velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min(-1)). both the accuracy and the reliability of this new ball machine appear satisfying enough for field testing and training. Key pointsThe reliability and accuracy of a new ball machine named 'Hightof' were assessed.The impact point was reproducible and similar on the right and left sides (±0.63 m).The precision was constant and did not increase with the intensity (e.g ball frequency).The coefficient of variation of the ball velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min(-1)).

  14. Laboratory demonstration of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D [B.P. Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region, Rusian Federation (Russian Federation)

    2004-01-31

    A common laboratory facility for creating glowing flying plasmoids akin to a natural ball lightning, allowing a number of experiments to be performed to investigate the main properties of ball lightning, is described. (methodological notes)

  15. Do changing levels of maternal exercise during pregnancy affect neonatal adiposity? Secondary analysis of the babies after SCOPE: evaluating the longitudinal impact using neurological and nutritional endpoints (BASELINE) birth cohort (Cork, Ireland).

    Science.gov (United States)

    Norris, Tom; McCarthy, Fergus P; Khashan, Ali S; Murray, Deidre M; Kiely, Mairead; Hourihane, Jonathan O'B; Baker, Philip N; Kenny, Louise C

    2017-12-01

    To investigate whether changing levels of exercise during pregnancy are related to altered neonatal adiposity. Secondary analysis of data from a prospective cohort study. Cork, Ireland. 1200 mother - infant pairs recruited as part of a prospective birth cohort, Babies After SCOPE: Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints (BASELINE). Neonatal adiposity was assessed within several days of birth using air displacement plethysmography (PEAPOD). Per cent body fat (BF%) as a continuous outcome and a pair of dichotomous variables; high or low adiposity, representing BF% >90th or high adiposity). At 20 weeks' gestation, analyses revealed that relative to women who do not change their exercise level up to 20 weeks, those women who decreased their exercise level were more likely to give birth to a neonate with adiposity above the 90th centile (OR 1.62, 95% CI 1.07 to 2.46). This association was maintained after adjustment for putative confounders (OR 1.62, 95% CI 1.06 to 2.47). We observed a possible critical period for the association between changing exercise levels and neonatal adiposity, with no association observed with exercise recall for the first 15 weeks of gestation, but an association with a decreasing level of exercise between 15 and 20 weeks. These results should be interpreted in line with the limitations of the study and further studies utilising objectively measured estimates of exercise are required in order to replicate these findings. NCT01498965. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  16. Plasma theory of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Ostapenko, V.I.; Tolpygo, K.B.

    1984-02-01

    The high-energy density inside the ball lightning is due to existence of intense plasma oscillations and high kinetic and potential energy of electron gas which form a pulsating ball vibrating relative to the nearly stationary ionic ball. At sublight velocities of electrons one can neglect the processes of their scattering and recombination. One obtains a relation between parameters of the plasma ball from the condition of equality of excess pressure of ions and that of Madelung forces. The high lifetime of the ball lighting is connected with small Landau damping for the longest wave vibrations.

  17. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  18. Real-Time Visual Feedback of Airflow in Voice Training: Aerodynamic Properties of Two Flow Ball Devices.

    Science.gov (United States)

    Lã, Filipa M B; Wistbacka, Greta; Andrade, Pedro Amarante; Granqvist, Svante

    2017-05-01

    Flow ball devices have been used as teaching tools to provide visual real-time feedback of airflow during singing. This study aims at exploring static back pressure and ball height as function of flow for two devices, marketed as flow ball and floating ball game. This is a comparative descriptive study. A flow-driven vocal tract simulator was used to investigate the aerodynamic properties of these two devices, testing them for four different ball sizes. The flow range investigated was between 0 and 0.5 L/s. Audio, flow, pressure, and ball height were recorded. The flow pressure profiles for both tested devices were similar to those observed in previous studies on narrow tubes. For lifting the ball, both devices had a flow and a pressure threshold. The tested floating ball game required considerably higher back pressure for a given flow as compared with the flow ball. Both tested devices have similar effects on back pressure as straws of 3.7 and 3.0 mm in diameter for the flow ball and the floating ball game, respectively. One might argue that both devices could be used as tools for practicing semi-occluded vocal tract exercises, with the additional benefit of providing real-time visual feedback of airflow during phonation. The flow threshold, combined with the flow feedback, would increase awareness of flow, rather than of pressure, during exercises using a flow ball device. Published by Elsevier Inc.

  19. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  20. Ball Lightning Investigations

    Science.gov (United States)

    Bychkov, V. L.; Nikitin, A. I.; Dijkhuis, G. C.

    Ball lightning (BL) researches' review and theoretical models of three different authors are presented. The general review covers investigations from 1838 until the present day, and includes a discussion on observation data, experimental modeling, and theoretical approaches. Section 6.1 is written by Bychkov and Nikitin; authors of the sections 6.2, 6.3 and 6.4 are, respectively, Bychkov, Nikitin and Dijkhuis.

  1. Preterm Birth

    Science.gov (United States)

    ... After hours (404) 639-2888 Contact Media Preterm Birth Recommend on Facebook Tweet Share Compartir Preterm birth ... Can anything be done to prevent a preterm birth? Preventing preterm birth remains a challenge because there ...

  2. Cesarean Birth

    Science.gov (United States)

    ... QUESTIONS LABOR, DELIVERY, AND POSTPARTUM CARE FAQ006 Cesarean Birth (C-section) • What is cesarean birth? • What are the reasons for cesarean birth? • Is a cesarean birth necessary if I have ...

  3. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  4. Individual ball possession in soccer.

    Directory of Open Access Journals (Sweden)

    Daniel Link

    Full Text Available This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC, Individual Ball Action (IBA, Individual Ball Control (IBC, Team Ball Possession (TBP, Team Ball Control (TBC und Team Playmaking (TPM according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min and the longest for goalkeepers (1:38 ± 0:58 min, central defenders (1:38 ± 1:09 min and central midfielders (1:27 ± 1:08 min. The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.

  5. Individual ball possession in soccer.

    Science.gov (United States)

    Link, Daniel; Hoernig, Martin

    2017-01-01

    This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC), Individual Ball Action (IBA), Individual Ball Control (IBC), Team Ball Possession (TBP), Team Ball Control (TBC) und Team Playmaking (TPM) according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min) and the longest for goalkeepers (1:38 ± 0:58 min), central defenders (1:38 ± 1:09 min) and central midfielders (1:27 ± 1:08 min). The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.

  6. Care in a birth center according to the recommendations of the World Health Organization

    Directory of Open Access Journals (Sweden)

    Flora Maria Barbosa da Silva

    2013-10-01

    Full Text Available Birth centers are maternal care models that use appropriate technology when providing care to birthing women. This descriptive study aimed to characterize intrapartum care in a freestanding birth center, in light of the practices recommended by the World Health Organization (WHO, with 1,079 assisted births from 2006 to 2009 in the Sapopemba Birth Center, São Paulo, Brazil. Results included the use of intermittent auscultation (mean=7 controls; maternal positions during delivery: semi-sitting (82.3%, side-lying (16.0%, other positions (1.7%, oral intake (95.6%; companionship (93.3%; exposure to up to three vaginal examinations (85.4%, shower bathing (84.0%, walking (68.0%, massage (60.1%, exercising with a Swiss ball (51.7%; amniotomy (53.4%, oxytocin use during the first (31.0% and second stages of labor (25.8%, bath immersion (29.3% and episiotomy (14.1%. In this birth center, care providers used practices recommended by the WHO, although some practices might have been applied less frequently.

  7. Localized plasma balls

    Energy Technology Data Exchange (ETDEWEB)

    Figueras, Pau; Tunyasuvunakool, Saran [DAMTP, Centre for Mathematical Sciences,Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2014-06-04

    In this paper we numerically construct localized black hole solutions in the IR end of the confining geometry of the AdS soliton, Witten’s early holographic model for confinement. These black holes should be thought of as finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrized by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, these these black holes spread out in the directions parallel to IR end of the space-time, whilst their extent in the holographic radial direction remains finite. In these new black hole backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy.

  8. Localized plasma balls

    International Nuclear Information System (INIS)

    Figueras, Pau; Tunyasuvunakool, Saran

    2014-01-01

    In this paper we numerically construct localized black hole solutions in the IR end of the confining geometry of the AdS soliton, Witten’s early holographic model for confinement. These black holes should be thought of as finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrized by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, these these black holes spread out in the directions parallel to IR end of the space-time, whilst their extent in the holographic radial direction remains finite. In these new black hole backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy

  9. Behaviour of a Bouncing Ball

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    The bounce of a ball is a seemingly innocuous event that can be used to illustrate many aspects of elementary and even advanced mechanics. Both normal and oblique bounces on a rigid surface are considered in this article, emphasizing qualitative features of the bounce process. If the ball bounces at an oblique angle then it can slide throughout…

  10. Reflections on a Bouncing Ball

    Science.gov (United States)

    Rohr, Jim; Lopez, Veronica; Rohr, Tyler

    2014-01-01

    While observing the bounce heights of various kinds of sports balls dropped from different heights onto a variety of surfaces, we thought of the following question: Could measurements of drop and bounce heights of balls of different diameters, but of the same material, falling from different heights, but on the same surface, be expressed by a…

  11. Structure of laboratory ball lightning

    Science.gov (United States)

    Ito, Tsuyohito; Tamura, Tomoya; Cappelli, Mark A.; Hamaguchi, Satoshi

    2009-12-01

    Trajectories of self-sustained laboratory ball lightning, generated by arc discharges with silicon, are investigated for understanding the possibility of buoyant flight. Extremely low apparent densities are found, nearly approaching that of standard air. The freely buoyant balls are observed to survive for about 0.1 s, with significantly buoyant balls surviving for several seconds. These ball lightning objects are found to have a density and size that can easily allow them to be carried by a gentle breeze of a few meters per second. The results are interpreted by a model that is an extension of that first proposed by Abrahamson and Dinniss [J. Abrahamson and J. Dinniss, Nature (London) 403, 519 (2000)]. The buoyant behavior of ball lightning seen in our experiments is believed to arise as a result of the formation of a nanoparticle oxide network growing from a molten silicon core.

  12. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  13. Prediction of tar ball formation

    International Nuclear Information System (INIS)

    Khelifa, A.; Gamble, L.

    2006-01-01

    The presence of small tar balls ranging in size from less than a millimetre to 60 centimetres have been observed during cleanup assessment operations following accidental oil spills on water. The tar balls are composed of heavy oil residues and suspended particulate matter (SPM) from the water column. They can be found on shorelines, settled on the seafloor and floating at or near the water surface. Their abundance on the shorelines varies from site to site and depends on the conditions of the spill and mixing conditions. Aggregation between SPM and micro-sized oil droplets occurs naturally in coastal waters and enhances the dispersion of spilled oil. Although tar balls are among the important end states of spilled oil in the marine environment, no model exists to estimate the percentage of the spilled oil that becomes tar balls. This paper offered some insight into the modeling of tar ball formation. Current modeling understanding of oil-SPM aggregate formation was used to predict tar ball formation. The formation of oil droplets was examined with respect to a range of conditions under which the formation of large droplets is expected. The role of aggregation was then presented to demonstrate the effects of concentration and type of SPM on the buoyancy of tar balls. Good agreement was found between modeling results and field data reported in the literature regarding the size and density of tar balls. Oil viscosity and mixing energy were found to be the main factors controlling the formation of tar balls. The aggregation of tar balls with SPM and shoreline material results in significant increases or decreases in density, depending on the type and concentration of SPM. 42 refs., 2 tabs., 6 figs

  14. Crystal Ball at PEP

    International Nuclear Information System (INIS)

    Bartel, W.; Bulos, F.; Luke, D.; Peck, C.; Strauch, K.

    1975-01-01

    The modifications to the SPEAR version of the Crystal Ball required by the higher energies at PEP are discussed. Since the hadron multiplicity is expected to rise as log s, their average energy must rise. On the other hand, if the hadrons are produced in jets, the low energy part of their spectrum is not heavily depleted. This implies that modifications for high energy particles should not deteriorate low energy performance. An external iron calorimeter for measuring the high energy hadrons, charged and neutral, is considered. To improve the angular resolution on γ's, an active internal converter has been studied, estimates have been made of its expected performance, and difficulties requiring further study have been outlined

  15. Development of Stick and Ball Sports on Gateball

    Directory of Open Access Journals (Sweden)

    Indriyanti

    2017-10-01

    Full Text Available The purpose of this research is to make product design development of stick and ball sports in gateball. The approach used in this study is a method of Research and Development. The subject of this research is the Central Java on gateball club event gateball in Semarang and Yogyakarta. Experts and expert expert gateball expert in mechanical engineering. The data analysis phase the work field, and the data analysis stage include observation, observation, interviews, and documentation of the test kefektifan products, expert judgment expert expert gateball and expert mechanical engineering expert. The results of this research are stick and ball exercise for beginner players gateball gateball. The result of the validator 3 expert expert from the expert gateball and expert mechanical engineering product validation data beginning the first phase obtained a score above 73 definitions of the criteria of “good”, on the second stage of the product validation data obtained a score above the 81 criteria for “excellent”. The results of the interviews to the development of gateball players 19 stick and ball gateball can not be used to play in a match and can be used for subsequent exercises but for beginners a product development tool model stick and ball gateball “ INC. “can be used to enhance the ability of basic techniques in motion game for players, gateball.

  16. Unsolved Mystery of Ball Lightning

    Science.gov (United States)

    Bychkov, V. L.

    Ball lightning is an unusual phenomenon always drawing attention of people. There are still questions about its origination, features, interaction with environment, and phenomena related to it. On a way of studying this phenomenon, there are a lot of difficulties, the basic of them is insufficiency of authentic, scientific data. The chapter sets as the purpose to interest the reader in the problem, to describe conditions of ball lightning occurrence, theories, and its hypotheses explanation, to include readers in a circle of experimental searches in creation of a ball lightning and its analogues, and to describe fascination of a problem and difficulty of its solution.

  17. Swiss ball abdominal crunch with added elastic resistance is an effective alternative to training machines

    DEFF Research Database (Denmark)

    Sundstrup, Emil; Jakobsen, Markus D; Andersen, Christoffer H

    2012-01-01

    to induce high level of muscle activation. PURPOSE: To compare muscle activation as measured by electromyography (EMG) of global core and thigh muscles during abdominal crunches performed on Swiss ball with elastic resistance or on an isotonic training machine when normalized for training intensity. METHODS......BACKGROUND: Swiss ball training is recommended as a low intensity modality to improve joint position, posture, balance, and neural feedback. However, proper training intensity is difficult to obtain during Swiss ball exercises whereas strengthening exercises on machines usually are performed......: 42 untrained individuals (18 men and 24 women) aged 28-67 years participated in the study. EMG activity was measured in 13 muscles during 3 repetitions with a 10 RM load during both abdominal crunches on training ball with elastic resistance and in the same movement utilizing a training machine...

  18. INVESTIGATION OF ANGULAR BALL BEARING WEAR

    Directory of Open Access Journals (Sweden)

    A. L. Savchenko

    2006-01-01

    Full Text Available Wearing process of balls in an angular ball bearing has been investigated in the paper. Force affecting a separator from the side of balls is determined theoretically. Wear rate may be calculated with a formula for abrasive wear while substituting numerical parameter values of the investigated ball bearing for formula symbols.

  19. Inscribed Balls and Their Centers

    Science.gov (United States)

    Balashov, M. V.

    2017-12-01

    A ball of maximal radius inscribed in a convex closed bounded set with a nonempty interior is considered in the class of uniformly convex Banach spaces. It is shown that, under certain conditions, the centers of inscribed balls form a uniformly continuous (as a set function) set-valued mapping in the Hausdorff metric. In a finite-dimensional space of dimension n, the set of centers of balls inscribed in polyhedra with a fixed collection of normals satisfies the Lipschitz condition with respect to sets in the Hausdorff metric. A Lipschitz continuous single-valued selector of the set of centers of balls inscribed in such polyhedra can be found by solving n + 1 linear programming problems.

  20. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    A technique involving a small ball with a transmitter embedded inside it has been successfully tested in Sector 7-8. The ball is sent through the LHC beam pipes to check the LHC interconnections. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI). During the tests the ball is inserted very carefully into the vacuum chamber.A game of ping-pong at the LHC? On 13 September a rather unusual test was carried out in Sector 7-8 of the accelerator. A ball just a bit smaller than a ping-pong ball was carefully introduced into one of the accelerator’s two vacuum pipes, where it travelled 800 metres in the space of a few mi...

  1. Birth Defects

    Science.gov (United States)

    A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of ... in the United States is born with a birth defect. A birth defect may affect how the ...

  2. Berkeley High-Resolution Ball

    International Nuclear Information System (INIS)

    Diamond, R.M.

    1984-10-01

    Criteria for a high-resolution γ-ray system are discussed. Desirable properties are high resolution, good response function, and moderate solid angle so as to achieve not only double- but triple-coincidences with good statistics. The Berkeley High-Resolution Ball involved the first use of bismuth germanate (BGO) for anti-Compton shield for Ge detectors. The resulting compact shield permitted rather close packing of 21 detectors around a target. In addition, a small central BGO ball gives the total γ-ray energy and multiplicity, as well as the angular pattern of the γ rays. The 21-detector array is nearly complete, and the central ball has been designed, but not yet constructed. First results taken with 9 detector modules are shown for the nucleus 156 Er. The complex decay scheme indicates a transition from collective rotation (prolate shape) to single- particle states (possibly oblate) near spin 30 h, and has other interesting features

  3. MIPP Plastic Ball electronics upgrade

    Science.gov (United States)

    Baldin, Boris; MIPP Collaboration

    2009-10-01

    An upgrade electronics design for Plastic Ball detector is described. The Plastic Ball detector was a part of several experiments in the past and its back portion (proposed to be used in Main Injector Particle Production (MIPP)) consists of 340 photomultipliers equipped with a sandwich scintillator. The scintillator sandwich has fast and slow signal component with decay times 10 ns and 1 μs, respectively. The upgraded MIPP experiment will collect up to 12,000 events during each 4 s spill and read them out in ˜50 s between spills. The MIPP data acquisition system will employ deadtime-less concept successfully implemented in Muon Electronics of Dzero experiment at Fermilab An 8-channel prototype design of the Plastic Ball Front-End (PBFE) implementing these requirements is discussed. Details of the schematic design, simulation and prototype test results are discussed.

  4. Breech birth

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000623.htm Breech birth To use the sharing features on this page, ... safer for your baby to pass through the birth canal. In the last weeks of pregnancy, your ...

  5. Application of the Blobo bluetooth ball in wrist rehabilitation training.

    Science.gov (United States)

    Hsieh, Wei-Min; Hwang, Yuh-Shyan; Chen, Shih-Ching; Tan, Sun-Yen; Chen, Chih-Chen; Chen, Yu-Luen

    2016-01-01

    [Purpose] The introduction of emerging technologies such as the wireless Blobo bluetooth ball with multimedia features can enhance wrist physical therapy training, making it more fun and enhancing its effects. [Methods] Wrist injuries caused by fatigue at work, improper exercise, and other conditions are very common. Therefore, the reconstruction of wrist joint function is an important issue. The efficacy of a newly developed integrated wrist joint rehabilitation game using a Blobo bluetooth ball with C# software installed was tested in wrist rehabilitation (Flexion, Extension, Ulnar Deviation, Radial Deviation). [Results] Eight subjects with normal wrist function participated in a test of the system's stability and repeatability. After performing the Blobo bluetooth ball wrist physical therapy training, eight patients with wrist dysfunction experienced approximately 10° improvements in range of motion (ROM) of flexion extension, and ulnar deviation and about 6° ROM improvement in radial deviation. The subjects showed progress in important indicators of wrist function. [Conclusion] This study used the Blobo bluetooth ball in wrist physical therapy training and the preliminary results were encouraging. In the future, more diverse wrist or limb rehabilitation games should be developed to meet the needs of physical therapy training.

  6. The effects of virtual reality game exercise on balance and gait of the elderly.

    Science.gov (United States)

    Park, Eun-Cho; Kim, Seong-Gil; Lee, Chae-Woo

    2015-04-01

    [Purpose] The aim of this study was to examine the effects of ball exercise as a general exercise on the balance abilities of elderly individuals by comparing ball exercise with virtual reality exercise. [Subjects and Methods] Thirty elderly individuals residing in communities were randomly divided into a virtual reality game group and a ball exercise group and conducted exercise for 30 min 3 times a week for 8 weeks. [Results] Step length increased significantly, and the average sway speed and Timed Up and Go time significantly decreased in both groups. A comparison of sway length after the intervention between the two groups revealed that the virtual reality game exercise resulted in a reduction than the ball exercise. [Conclusion] The results of this study indicated that the virtual reality game exercise may improve balance and gait of elderly individuals in communities.

  7. Physical nature of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Stakhanov, I.P.

    1979-01-01

    An analysis is made of results obtained from the observations of ball lightning. Principal attention is given to data obtained during the last two decades. A brief critique is also offered on hypotheses about its origin. A more detailed presentation is made of the cluster hypothesis according to which ball lightning consists of complex compounds of ions and neutral molecules. The book is intended for a broad spectrum of readers, but is particularly directed toward those with a knowledge of physics and chemistry. 70 references, 24 figures, 17 tables.

  8. Ball lightning risk to aircraft

    Science.gov (United States)

    Doe, R.; Keul, A.

    2009-04-01

    Lightning is a rare but regular phenomenon for air traffic. Aircraft are designed to withstand lightning strikes. Research on lightning and aircraft can be called detailed and effective. In the last 57 years, 18 reported lightning aviation disasters with a fatality figure of at least 714 persons occurred. For comparison, the last JACDEC ten-year average fatality figure was 857. The majority encountered lightning in the climb, descent, approach and/or landing phase. Ball lightning, a metastable, rare lightning type, is also seen from and even within aircraft, but former research only reported individual incidents and did not generate a more detailed picture to ascertain whether it constitutes a significant threat to passenger and aircraft safety. Lacking established incident report channels, observations were often only passed on as "air-travel lore". In an effort to change this unsatisfactory condition, the authors have collected a first international dataset of 38 documented ball lightning aircraft incidents from 1938 to 2001 involving 13 reports over Europe, 13 over USA/Canada, and 7 over Russia. 18 (47%) reported ball lightning outside the aircraft, 18 (47%) inside, 2 cases lacked data. 8 objects caused minor damage, 8 major damage (total: 42%), only one a crash. No damage was reported in 18 cases. 3 objects caused minor crew injury. In most cases, ball lightning lasted several seconds. 11 (29%) incidents ended with an explosion of the object. A cloud-aircraft lightning flash was seen in only 9 cases (24%) of the data set. From the detailed accounts of air personnel in the last 70 years, it is evident that ball lightning is rarely, but consistently observed in connection with aircraft and can also occur inside the airframe. Reports often came from multiple professional witnesses and in several cases, damages were investigated by civil or military authorities. Although ball lightning is no main air traffic risk, the authors suggest that incident and accident

  9. Electron-Ionic Model of Ball Lightening

    OpenAIRE

    Fedosin, Sergey G.; Kim, Anatolii S.

    2001-01-01

    The model of ball lightning is presented where outside electron envelope is kept by inside volume of positive charges. The moving of electron in outside envelope is a reason of strong magnetic field, which controls the state of hot ionized air inside of ball lightning. The conditions of origins of ball lightning are investigated and the values of parameters for ball lightning of maximum power are calculated.

  10. Device Rotates Bearing Balls For Inspection

    Science.gov (United States)

    Burley, R. K.

    1988-01-01

    Entire surface of ball inspected automatically and quickly. Device holds and rotates bearing ball for inspection by optical or mechanical surface-quality probe, eddy-current probe for detection of surface or subsurface defects, or circumference-measuring tool. Ensures entire surface of ball moves past inspection head quickly. New device saves time and increases reliability of inspections of spherical surfaces. Simple to operate and provides quick and easy access for loading and unloading of balls during inspection.

  11. Generation of Laboratory Ball Lightning

    Energy Technology Data Exchange (ETDEWEB)

    Oreshko, A G [Moscow Aviation Institute (State Technical University), Volokolamskoe shosse 4, 125871 Moscow (Russian Federation)

    2006-07-15

    The phenomenon of energy conversion in the streams of directed electrons and ions into electromagnetic radiation was found out experimentally and proved theoretically. The direct proofs of the domain mechanism of the charged particles acceleration and mechanism of ball lightning generation were obtained and the theoretical calculations were refined.

  12. SECRET OF A BALL LIGHTNING

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-04-01

    Full Text Available A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming, in the end, the surrounding air into a steam cloud that transits into ferroelectric state under the magnetic field action.

  13. A Conjecture Concerning Ball Lightning

    OpenAIRE

    Sturrock, P. A.

    2016-01-01

    There is at present no theory that can explain the curious properties of ball lightning. This suggests that we may not be using the most appropriate concepts. The concept of a 'parallel space' may point the way to a valid theory.

  14. Laboratory-produced ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1994-05-01

    For 25 years I have actively been searching for the true nature of ball lightning and attempting to reproduce it at will in the laboratory. As one might expect, many unidentified lights in the atmosphere have been called ball lightning, including Texas Maffa lights (automobile headlights), flying saucers (UFOs), swamp gas in Ann Arbor, Michigan, etc. For 15 years I thought ball lightning was strictly a high-voltage phenomenon. It was not until 1984 when I was short-circuiting the electrical output of a diesel electric railroad locomotive that I realized that the phenomenon was related more to a high current. Although I am hoping for some other types of ball lightning to emerge such as strictly electrostatic-electromagnetic manifestations, I have been unlucky in finding laboratory provable evidence. Cavity-formed plasmodes can be made by putting a 2-inch burning candle in a home kitchen microwave oven. The plasmodes float around for as long as the microwave energy is present.

  15. Reflections on a Disco Ball

    Science.gov (United States)

    Ribeiro, Jair Lúcio Prados

    2016-01-01

    A disco ball is a spherical object covered with small plane mirrors. When light reflects on these mirrors, it is scattered in many directions, producing a novel effect. The mirror globe is usually set to rotate, creating a profusion of moving spots (Fig. 1). In this article, we present a geometrical description of the movement of these spots and…

  16. LHC gets the ball rolling

    CERN Document Server

    2007-01-01

    1. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI).2. During the tests the ball is inserted very carefully into the vacuum chamber.1. Le groupe pluridisciplinaire qui a mené le projet de balle RF pour vérifier les interconnexions avec, de gauche à droite, Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS) et Marek Gasior (AB/BI).2. Lors des tests, la balle est insérée dans la chambre à vide avec beaucoup de précaution.

  17. Eddy-Current Inspection of Ball Bearings

    Science.gov (United States)

    Bankston, B.

    1985-01-01

    Custom eddy-current probe locates surface anomalies. Low friction air cushion within cone allows ball to roll easily. Eddy current probe reliably detects surface and near-surface cracks, voids, and material anomalies in bearing balls or other spherical objects. Defects in ball surface detected by probe displayed on CRT and recorded on strip-chart recorder.

  18. Effects of Caffeine Supplementation on Performance in Ball Games.

    Science.gov (United States)

    Chia, Jingyi Shannon; Barrett, Laura Ann; Chow, Jia Yi; Burns, Stephen Francis

    2017-12-01

    Although a large body of evidence exists documenting the ergogenic properties of caffeine, most studies have focused on endurance performance. However, findings from endurance sports cannot be generalized to performance in ball games where, apart from having a high level of endurance, successful athletic performances require a combination of physiological, technical and cognitive capabilities. The purpose of this review was to critically evaluate studies that have examined the effect of a single dose of caffeine in isolation on one or more of the following performance measures: total distance, sprint performance, agility, vertical jump performance and accuracy in ball games. Searches of three major databases resulted in 19 studies (invasion games: 13; net-barrier games: 6) that evaluated the acute effects of caffeine on human participants, provided the caffeine dose administered, and included a ball games specific task or simulated match. Improvements in sprint performance were observed in 8 of 10 studies (80%), and vertical jump in 7 of 8 studies (88%). Equivocal results were reported for distance covered, agility and accuracy. Minor side effects were reported in 4 of 19 studies reviewed. Pre-exercise caffeine ingestion between 3.0 and 6.0 mg/kg of body mass appears to be a safe ergogenic aid for athletes in ball games. However, the efficacy of caffeine varies depending on various factors, including, but not limited to, the nature of the game, physical status and caffeine habituation. More research is warranted to clarify the effects of caffeine on performance measures unique to ball games, such as agility and accuracy. It is essential that athletes, coaches and practitioners evaluate the risk-benefit ratio of caffeine ingestion strategies on an individual case-by-case basis.

  19. Energy cost and energy sources of ball routine in rhythmic gymnasts.

    Science.gov (United States)

    Guidetti, L; Baldari, C; Capranica, L; Persichini, C; Figura, F

    2000-04-01

    The energy cost and the different energy sources of competitive rhythmic ball-routines were assessed in nine young elite rhythmic gymnasts (13-16 years of age). The overall energy requirement of ball exercise (VO2eq) was obtained by adding the amount of VO2 during exercise above resting (VO2ex) to the VO2 up to the fast component of recovery (VO2al) and to the energy equivalent of peak blood lactate accumulation (VO2la-) of recovery. The lactate (La) curve up to 25 minutes of recovery always showed La peaks at 3 min after exercise (4.0 +/- 0.4 mmol/l) and values still above rest at 25 min (2.3 +/- 0.5 mmol/l). Although ball routines were short in duration (90 s), the metabolic power requirement was 1.1 times higher than the subject's VO2max. The energy cost (VO2eq) amounted to 81 +/- 5 ml x kg(-1). Higher fractions of VO2eq were VO2ex 49% and VO2al 42%, while the remaining 9% was due to VO2la-. The aerobic source resulted in the most utilized system due to the subjects' high VO2max (52.7 ml x kg(-1) x min(-1)) and anaerobic threshold (LT = 84.4%). The HR and the peak lactate values of ball routine were similar to the values recorded at LT step during treadmill test. Although the HR and VO2 values were significantly correlated (during pre-exercise, exercise, and fast recovery), the exercise intensity derived from HR Kanvonen method during ball routine did not correspond to the % of VO2max.

  20. Training Munitions Health Risk Assessment No. 39-EJ-1485-00. Residential Exposure from Inhalation of Air Emissions from the M33 .50 Caliber Ball Cartridge

    National Research Council Canada - National Science Library

    Coakley, Stafford

    2001-01-01

    ... .50 Caliber Ball Cartridge. This document present the evaluation of the potential for adverse human health effects to the offsite residents breathing air emissions following the use of military firing ranges during training exercises...

  1. Training Munitions Health Risk Assessment No. 39-EJ-1485-00 Residential Exposure from Inhalation of Air Emissions from the M80 7.62-MM Ball Cartridge

    National Research Council Canada - National Science Library

    Chang, Hsieng-Ye

    2001-01-01

    ... of the 7.62 mm Ball Cartridge. This document presents the evaluation of the potential for adverse human health effects to the offsite residents breathing air emissions following the use of military firing ranges during training exercises...

  2. Improvements of condenser performance with granulate balls

    International Nuclear Information System (INIS)

    Bratthaell, L.

    1986-05-01

    At the nuclear power plant Oskarshamn has during time Nov 1983 - Apr 1985 test series been done to investigate the improvements of condensor performance with granulate balls. This type of ball is a normal sponge rubber ball coated with granulated plastic material. This material is, different from carborundum and pumice not abrasive to the tube material. The test results show that granulate balls give an improvement of the overall heat transfer coefficient of 5-7 percent compared to continous cleaning with normal sponge rubber balls. Granulate balls remove the utmost thin coating of organic material that the spong rubber balls are not able to remove and a practically metallic clean surface is established. This has been verified by laboratory inspection of tubes withdrawn from the tube bundle and site inspections of the condenser. When the condenser is cleaned by granulate balls during a period of about three days it is possible to keep the performance at a high level for a long time with continous cleaning with normal sponge rubber balls. After about three days the plastic layer on the balls is practically worned out. The balls have during that time fulfilled their function. The improvement in condenser temperature is 1,0-1,5 degree C. For the 02-turbine this means additional delivered energy of about 15000 MWh per year. (author)

  3. Ball mounting fixture for a roundness gage

    Science.gov (United States)

    Gauler, A.L.; Pasieka, D.F.

    1983-11-15

    A ball mounting fixture for a roundness gage is disclosed. The fixture includes a pair of chuck assemblies oriented substantially transversely with respect to one another and mounted on a common base. Each chuck assembly preferably includes a rotary stage and a wobble plate affixed thereto. A ball chuck affixed to each wobble plate is operable to selectively support a ball to be measured for roundness, with the wobble plate permitting the ball chuck to be tilted to center the ball on the axis of rotation of the rotary stage. In a preferred embodiment, each chuck assembly includes a vacuum chuck operable to selectively support the ball to be measured for roundness. The mounting fixture enables a series of roundness measurements to be taken with a conventional rotating gagehead roundness instrument, which measurements can be utilized to determine the sphericity of the ball. 6 figs.

  4. Ceramic Rail-Race Ball Bearings

    Science.gov (United States)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  5. Polymer-composite ball lightning.

    Science.gov (United States)

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads.

  6. Measurements of drag and lift on smooth balls in flight

    Science.gov (United States)

    Cross, Rod; Lindsey, Crawford

    2017-07-01

    Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

  7. How to create ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1991-01-01

    Procedures are given on how to produce ball lightning. Necessary equipment includes a transformer of 150,000 watts capable of providing approximately 10,000 amperes at 15 volts, 60 cycles; thick one inch cables of stranded wire leading into a 3 by 4 by 1 foot plastic tank; a quarter inch thick 4 by 6 inch aluminum plate to be used as one of the discharge electrodes; and another electrode of heavy copper wire with the insulation stripped back 6 inches.

  8. Birthing Classes

    Science.gov (United States)

    ... management options. Breastfeeding basics. Caring for baby at home. Birthing classes are not just for new parents, though. ... midwife. Postpartum care. Caring for your baby at home, including baby first aid. Lamaze One of the most popular birthing techniques in the U.S., Lamaze has been around ...

  9. Ball Screw Actuator Including a Stop with an Integral Guide

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  10. Estudo comparativo entre exercícios com dinamômetro isocinético e bola terapêutica na lombalgia crônica de origem mecânica Comparison between isokinetic dynamometer and therapeutic ball exercises in chronic low-back pain of mechanical origin

    Directory of Open Access Journals (Sweden)

    Cíntia Domingues de Freitas

    2008-12-01

    Full Text Available O objetivo foi avaliar os efeitos dos exercícios de fortalecimento de tronco sobre a dor lombar crônica de origem mecânica e comparar o uso do dinamômetro isocinético e da bola terapêutica. Dezenove pacientes com dor lombar crônica foram distribuidos randomicamente em dois grupos, para fortalecimento do tronco: grupo bola (5 homens e 5 mulheres, idade média 31,2±8,2 e grupo dinamômetro (2 homens e 7 mulheres, idade média 37,9±11,2. Os grupos foram tratados em duas sessões semanais, por três meses, e avaliados antes e após o tratamento, quanto à dor (escala visual analógica, incapacidades funcionais (Questionário de Roland-Morris, mobilidade do tronco (teste de Schöber e distância do 3º dedo ao solo e força concêntrica dos flexores e extensores de tronco, no dinamômetro isocinético Cybex 6000. Os parâmetros avaliados foram: pico de torque, ângulo de pico de torque, potência, trabalho, tempo de aceleração e a relação flexores/extensores. Os dados foram tratados estatisticamente, sendo adotado um nível de significância de 5%. Foi observada uma melhora significante (pThis study aimed at assessing the effects of trunk strengthening exercises on chronic, mechanical low-back pain and compare the use of isokinetic dynamometer and therapeutic ball. Nineteen patients with chronic low back pain were randomly divided into two groups of trunk muscle strengthening, namely the ball group (5 men and 5 women, mean age 31,2±8,2 and the dynamometer group (2 men and 7 women, mean age 37.9±11.2. Patients attended two weekly sessions during three months and were evaluated before and after treatment as to pain (visual analog scale, functional disability (Roland Morris questionnaire, mobility (Schöber and fingertip-to-floor tests, and trunk concentric extensor and flexor muscles force (by the isokinetic dynamometer. The parameters selected to evaluate muscular performance were: peak torque, peak torque angle, power, work

  11. Fluid Mechanics of Cricket and Tennis Balls

    Science.gov (United States)

    Mehta, Rabindra D.

    2009-11-01

    Aerodynamics plays a prominent role in defining the flight of a ball that is struck or thrown through the air in almost all ball sports. The main interest is in the fact that the ball can often deviate from its initial straight path, resulting in a curved, or sometimes an unpredictable, flight path. It is particularly fascinating that that not all the parameters that affect the flight of a ball are always under human influence. Lateral deflection in flight, commonly known as swing, swerve or curve, is well recognized in cricket and tennis. In tennis, the lateral deflection is produced by spinning the ball about an axis perpendicular to the line of flight, which gives rise to what is commonly known as the Magnus effect. It is now well recognized that the aerodynamics of sports balls are strongly dependent on the detailed development and behavior of the boundary layer on the ball's surface. A side force, which makes a ball curve through the air, can also be generated in the absence of the Magnus effect. In one of the cricket deliveries, the ball is released with the seam angled, which trips the laminar boundary layer into a turbulent state on that side. The turbulent boundary layer separates relatively late compared to the laminar layer on the other side, thereby creating a pressure difference and hence side force. The fluid mechanics of a cricket ball become very interesting at the higher Reynolds numbers and this will be discussed in detail. Of all the round sports balls, a tennis ball has the highest drag coefficient. This will be explained in terms of the contribution of the ``fuzz" drag and how that changes with Reynolds number and ball surface wear. It is particularly fascinating that, purely through historical accidents, small disturbances on the ball surface, such as the stitching on cricket balls and the felt cover on tennis balls are all about the right size to affect boundary layer transition and development in the Reynolds numbers of interest. The fluid

  12. Electric charge of a lightning ball

    Science.gov (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.; Petrushov, N. A.

    2016-09-01

    The electric charge of a lightning ball is found by comparing the electrohydrodynamic stabilities of a charged drop in an electrostatic suspension and a lightning ball floating in a superposition of the gravitational field and the surface electric field. It has been assumed that the electric field strength at the surface is limited by a breakdown value. For a lightning ball radius of 15 cm, its charge is estimated as several microcoulombs. Accordingly, the density of electrostatic energy accumulated in the lightning ball is on the order of one-hundredth of a joule per square centimeter. The density of the material that constitutes the lightning ball has been estimated for the case when the electric field strength at the site of its origination is several times higher than that in fine weather. The density of the lightning ball turns out to differ from that of air by only a few percents.

  13. Multifractal properties of ball milling dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Budroni, M. A., E-mail: mabudroni@uniss.it; Pilosu, V.; Rustici, M. [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, Via Vienna 2, Sassari 07100 (Italy); Delogu, F. [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, Cagliari 09123 (Italy)

    2014-06-15

    This work focuses on the dynamics of a ball inside the reactor of a ball mill. We show that the distribution of collisions at the reactor walls exhibits multifractal properties in a wide region of the parameter space defining the geometrical characteristics of the reactor and the collision elasticity. This feature points to the presence of restricted self-organized zones of the reactor walls where the ball preferentially collides and the mechanical energy is mainly dissipated.

  14. Birth Weight

    Science.gov (United States)

    ... may become sick in the first days of life or develop infections. Others may suffer from longer-term problems such as delayed motor and social development or learning disabilities. High birth weight babies are often big because ...

  15. Birth Plans

    Science.gov (United States)

    ... licensed to handle low-risk births and whose philosophy emphasizes educating expectant parents about the natural aspects ... Partner Message About Us Contact Us Partners Editorial Policy Permissions Guidelines Privacy Policy & Terms of Use Notice ...

  16. The Soccer-Ball Problem

    Science.gov (United States)

    Hossenfelder, Sabine

    2014-07-01

    The idea that Lorentz-symmetry in momentum space could be modified but still remain observer-independent has received quite some attention in the recent years. This modified Lorentz-symmetry, which has been argued to arise in Loop Quantum Gravity, is being used as a phenomenological model to test possibly observable effects of quantum gravity. The most pressing problem in these models is the treatment of multi-particle states, known as the 'soccer-ball problem'. This article briefly reviews the problem and the status of existing solution attempts.

  17. Crystal ball data acquisition system

    International Nuclear Information System (INIS)

    Chestnut, R.; Kiesling, C.; Bloom, E.; Bulos, F.; Gaiser, J.; Godfrey, G.; Oreglia, M.; Partridge, R.; Peck, C.; Porter, F.; Aschman, D.; Cavali-Sforza, M.; Coyne, D.; Sadrozinski, H.; Kollmann, W.; Richardson, M.

    1979-01-01

    The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A ''physics pipeline'' allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented

  18. [Birth hypoxia].

    Science.gov (United States)

    Větr, M

    2015-03-01

    Evaluation of the commonly used laboratory and clinical parameters of the newborn shortly after birth. Check thresholds acidemia, and in relation to the method of termination of pregnancy. Retrospective epidemiological study. Department of Obstetrics and Gynecology, University Hospital, Olomouc. Of the 26,869 children born in the years 2000 to 2013 Inclusion criteria (complete clinical and laboratory findings after birth) fulfill 23,471 (87.4%) neonates. Methods for evaluation of newborns included Apgar score calculation and arterial umbilical cord blood pH and lactate analysis. A total of 0.7% (157) of the neonates had severe acidosis pH below 7.00 arterial umbilical cord blood, its prevalence varies annually between 0.1 to 1.1%. Cutoff lactate in relation to pH reserves. Operating cesarean births in particular accounts for more than half of those with worse clinical findings Apgar and pH <7.00, but only 30% supratreshold lactate values. Also worse clinical evaluation after caesarean section is not in accordance with the laboratory findings. Vaginal surgery, especially forceps have a significant share of severe acidosis than cesarean, regardless of their frequency. Risk factor of forceps to pH less 7.00,OR = 9.28 (5.39 -15.77), P = 0.0000000, while caesarean to pH less 7,00 had OR = 1.52 (1.08 to 2.14), P = 0.01408156. The results obtained confirm that acidosis after birth is quite common, although they may not have response on the clinical condition of the newborn after birth. Evaluation of Apgar is little objective for the detection of hypoxia during birth and is influenced by the immaturity of newborn and method of delivery. Lactate levels may contribute to an objective assessment of hypoxia during birth. Values above 6.3 mmol/l can be considered an important indicator of newborn acidosis and birth hypoxia.

  19. Systematic review of core muscle activity during physical fitness exercises.

    Science.gov (United States)

    Martuscello, Jason M; Nuzzo, James L; Ashley, Candi D; Campbell, Bill I; Orriola, John J; Mayer, John M

    2013-06-01

    A consensus has not been reached among strength and conditioning specialists regarding what physical fitness exercises are most effective to stimulate activity of the core muscles. Thus, the purpose of this article was to systematically review the literature on the electromyographic (EMG) activity of 3 core muscles (lumbar multifidus, transverse abdominis, quadratus lumborum) during physical fitness exercises in healthy adults. CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, PubMed, SPORTdiscus, and Web of Science databases were searched for relevant articles using a search strategy designed by the investigators. Seventeen studies enrolling 252 participants met the review's inclusion/exclusion criteria. Physical fitness exercises were partitioned into 5 major types: traditional core, core stability, ball/device, free weight, and noncore free weight. Strength of evidence was assessed and summarized for comparisons among exercise types. The major findings of this review with moderate levels of evidence indicate that lumbar multifidus EMG activity is greater during free weight exercises compared with ball/device exercises and is similar during core stability and ball/device exercises. Transverse abdominis EMG activity is similar during core stability and ball/device exercises. No studies were uncovered for quadratus lumborum EMG activity during physical fitness exercises. The available evidence suggests that strength and conditioning specialists should focus on implementing multijoint free weight exercises, rather than core-specific exercises, to adequately train the core muscles in their athletes and clients.

  20. Swiss ball abdominal crunch with added elastic resistance is an effective alternative to training machines.

    Science.gov (United States)

    Sundstrup, Emil; Jakobsen, Markus D; Andersen, Christoffer H; Jay, Kenneth; Andersen, Lars L

    2012-08-01

    Swiss ball training is recommended as a low intensity modality to improve joint position, posture, balance, and neural feedback. However, proper training intensity is difficult to obtain during Swiss ball exercises whereas strengthening exercises on machines usually are performed to induce high level of muscle activation. To compare muscle activation as measured by electromyography (EMG) of global core and thigh muscles during abdominal crunches performed on Swiss ball with elastic resistance or on an isotonic training machine when normalized for training intensity. 42 untrained individuals (18 men and 24 women) aged 28-67 years participated in the study. EMG activity was measured in 13 muscles during 3 repetitions with a 10 RM load during both abdominal crunches on training ball with elastic resistance and in the same movement utilizing a training machine (seated crunch, Technogym, Cesena, Italy). The order of performance of the exercises was randomized, and EMG amplitude was normalized to maximum voluntary isometric contraction (MVIC) EMG. When comparing between muscles, normalized EMG was highest in the rectus abdominis (Pexercises.

  1. Ball Nut Preload Diagnosis of the Hollow Ball Screw through Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Yi-Cheng Huang

    2018-01-01

    Full Text Available This paper studies the diagnostic results of hollow ball screws with different ball nut preload through the support vector machine (SVM process. The method is testified by considering the use of ball screw pretension and different ball nut preload. SVM was used to discriminate the hollow ball screw preload status through the vibration signals and servo motor current signals. Maximum dynamic preloads of 2%, 4%, and 6% ball screws were predesigned, manufactured, and conducted experimentally. Signal patterns with different preload features are separatedby SVM. The irregularity development of the ball screw driving motion current and rolling balls vibration of the ball screw can be discriminated via SVM based on complexity perception. The experimental results successfully show that the prognostic status of ball nut preload can be envisaged by the proposed methodology. The smart reasoning for the health of the ball screw is available based on classification of SVM. This diagnostic method satisfies the purposes of prognostic effectiveness on knowing the ball nut preload status

  2. A Comparative Study of Two Types of Ball-on-Ball Collision

    Science.gov (United States)

    White, Colin

    2017-01-01

    This paper describes three methods of measuring the coefficient of restitution (CoR) for two different types of ball-on-ball collision. The first collision type (for which two different CoR measurement procedures are described) is a static, hanging steel ball forming part of a Newton's cradle arrangement, which is then hit by its adjacent…

  3. Phenomenon of ball lightning and its outgrowths

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)]. E-mail: v_torchigin@mail.ru; Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)

    2005-03-28

    New physical phenomena deduced from properties of ball lightning are considered under assumption that ball lightning is a light bubble comprising of a thin spherical layer of compressed air where an intense light circulates in all possible directions. Explanation of behavior of autonomous luminous objects produced at gas discharge is presented.

  4. Fusion characteristics of ball lighting like configurations

    Energy Technology Data Exchange (ETDEWEB)

    Sanduloviciu, M.; Lozneanu, E. [Universitatea A1. I. Cuza, Iasi (Romania)

    1997-12-31

    Assuming that an already proposed self-organization physical scenario is at the origin of both ball lightnings as well as fireballs produced in high intensity electrical discharges, we suggest a new possibility to create fusion relevant ball lightning like configurations in laboratory. Perhaps this becomes possible by prolonging in a controllable way their lifetime and energy content. (author)

  5. Structural and dynamical properties of Yukawa balls

    International Nuclear Information System (INIS)

    Block, D; Kroll, M; Arp, O; Piel, A; Kaeding, S; Ivanov, Y; Melzer, A; Henning, C; Baumgartner, H; Ludwig, P; Bonitz, M

    2007-01-01

    To study the structural and dynamical properties of finite 3D dust clouds (Yukawa balls) new diagnostic tools have been developed. This contribution describes the progress towards 3D diagnostics for measuring the particle positions. It is shown that these diagnostics are capable of investigating the structural and dynamical properties of Yukawa balls and gaining insight into their basic construction principles

  6. Soccer Ball Lift Coefficients via Trajectory Analysis

    Science.gov (United States)

    Goff, John Eric; Carre, Matt J.

    2010-01-01

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…

  7. Protecting a Ball-Bearing-Deflection Monitor

    Science.gov (United States)

    Kuhr, George A.

    1987-01-01

    Deflectometer probe monitors deflection of ball-bearing race in liquid oxygen with aid of small window or diaphragm. Diaphragm or window isolates optical deflectometer from liquid oxygen or other fluid in ball bearing. At high pressures, diaphragm integral part of housing preferable to window, since there would be no leakage.

  8. Flicker Ball, Physical Education: 5551.34.

    Science.gov (United States)

    Stout, Paul L.

    This course outline is a guide for teaching skills of flicker ball in grades 7-12. The course format includes lectures, game situations, class tournaments, and tests that focus on mastery of skills, understanding of rules, and development of techniques in shooting and passing. Course content includes the following: (a) history of flicker ball, (b)…

  9. The principal time balls of New Zealand

    Science.gov (United States)

    Kinns, Roger

    2017-04-01

    Accurate time signals in New Zealand were important for navigation in the Pacific. Time balls at Wellington and Lyttelton were noted in the 1880 Admiralty list of time signals, with later addition of Otago. The time ball service at Wellington started in March 1864 using the first official observatory in New Zealand, but there was no Wellington time ball service during a long period of waterfront redevelopment during the 1880s. The time ball service restarted in November 1888 at a different harbour location. The original mechanical apparatus was used with a new ball, but the system was destroyed by fire in March 1909 and was never replaced. Instead, a time light service was inaugurated in 1912. The service at Lyttelton, near Christchurch, began in December 1876 after construction of the signal station there. It used telegraph signals from Wellington to regulate the time ball. By the end of 1909, it was the only official time ball in New Zealand, providing a service that lasted until 1934. The Lyttelton time ball tower was an iconic landmark in New Zealand that had been carefully restored. Tragically, the tower collapsed in the 2011 earthquakes and aftershocks that devastated Christchurch. A daily time ball service at Port Chalmers, near Dunedin, started in June 1867, initially using local observatory facilities. The service appears to have been discontinued in October 1877, but was re-established in April 1882 as a weekly service, with control by telegraph from Wellington. The service had been withdrawn altogether by the end of 1909. Auckland never established a reliable time ball service, despite provision of a weekly service for mariners by a public-spirited citizen between August 1864 and June 1866. A time ball was finally installed on the Harbour Board building in 1901, but the signal was unreliable and it ceased in 1902. Complaints from ships' masters led to various proposals to re-establish a service. These concluded with erection of a time ball on the new

  10. Study of soccer ball flight trajectory

    Directory of Open Access Journals (Sweden)

    Javorova Juliana

    2018-01-01

    Full Text Available In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.

  11. La balle et la plume

    Directory of Open Access Journals (Sweden)

    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  12. A model for ball lightning

    International Nuclear Information System (INIS)

    Fryberger, D.

    1994-10-01

    A model for ball lightning (BL) is described. It is based upon the vorton model for elementary particles, which exploits the symmetry between electricity and magnetism. The core, or driving engine, of BL in this model is comprised of a vorton-antivorton plasma. The energy of BL, which derives from nucleon decay catalyzed by this plasma, leads, through various mechanisms, to BL luminosity as well as to other BL features. It is argued that this model could also be a suitable explanation for other luminous phenomena, such as the unidentified atmospheric light phenomena seen at Hessdalen. It is predicted that BL and similar atmospheric luminous phenomena should manifest certain features unique to this model, which would be observable with suitable instrumentation

  13. Birth cohorts

    DEFF Research Database (Denmark)

    Andersen, Anne-Marie Nybo; Madsen, Mia

    2009-01-01

    ; provides practical guidance on how to set-up and maintain birth cohorts for completing family-based studies in life course epidemiology; describes how to undertake appropriate statistical analyses of family-based studies and correctly interpret results from these analyses; and provides examples...

  14. Cricket Ball Aerodynamics: Myth Versus Science

    Science.gov (United States)

    Mehta, Rabindra D.; Koga, Demmis J. (Technical Monitor)

    2000-01-01

    Aerodynamics plays a prominent role in the flight of a cricket ball released by a bowler. The main interest is in the fact that the ball can follow a curved flight path that is not always under the control of the bowler. ne basic aerodynamic principles responsible for the nonlinear flight or "swing" of a cricket ball were identified several years ago and many papers have been published on the subject. In the last 20 years or so, several experimental investigations have been conducted on cricket ball swing, which revealed the amount of attainable swing, and the parameters that affect it. A general overview of these findings is presented with emphasis on the concept of late swing and the effects of meteorological conditions on swing. In addition, the relatively new concept of "reverse" swing, how it can be achieved in practice and the role in it of ball "tampering", are discussed in detail. A discussion of the "white" cricket ball used in last year's World Cup, which supposedly possesses different swing properties compared to a conventional red ball, is also presented.

  15. BALL - biochemical algorithms library 1.3

    Directory of Open Access Journals (Sweden)

    Stöckel Daniel

    2010-10-01

    Full Text Available Abstract Background The Biochemical Algorithms Library (BALL is a comprehensive rapid application development framework for structural bioinformatics. It provides an extensive C++ class library of data structures and algorithms for molecular modeling and structural bioinformatics. Using BALL as a programming toolbox does not only allow to greatly reduce application development times but also helps in ensuring stability and correctness by avoiding the error-prone reimplementation of complex algorithms and replacing them with calls into the library that has been well-tested by a large number of developers. In the ten years since its original publication, BALL has seen a substantial increase in functionality and numerous other improvements. Results Here, we discuss BALL's current functionality and highlight the key additions and improvements: support for additional file formats, molecular edit-functionality, new molecular mechanics force fields, novel energy minimization techniques, docking algorithms, and support for cheminformatics. Conclusions BALL is available for all major operating systems, including Linux, Windows, and MacOS X. It is available free of charge under the Lesser GNU Public License (LPGL. Parts of the code are distributed under the GNU Public License (GPL. BALL is available as source code and binary packages from the project web site at http://www.ball-project.org. Recently, it has been accepted into the debian project; integration into further distributions is currently pursued.

  16. Training Munitions Health Risk Assessment NO. 39-EJ-1485-00 Residential Exposure from Inhalation of Air Emissions from the M1911.45 Caliber Ball Cartridge Department of Defense Identification Code: A475

    National Research Council Canada - National Science Library

    Coakley, Stafford

    2001-01-01

    ... .45 Caliber Ball Cartridge. This document presents the evaluation of the potential for adverse human health effects to the offsite residents breathing air emissions following the use of military firing ranges during training exercises...

  17. Training Munitions Health Risk Assessment No. 39-EJ-1485-00 Residential Exposure from Inhalation of Air Emissions from the M855 5.56-MM Tungsten Ball Cartridge

    National Research Council Canada - National Science Library

    Mobley, Joleen

    2001-01-01

    ... of the 5.56mm Tungsten Ball Cartridge. This document present the evaluation of the potential for adverse human health effects to the offsite residents breathing air emissions following the use of military firing ranges during training exercises...

  18. Compulsive Exercise

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Compulsive Exercise KidsHealth / For Parents / Compulsive Exercise What's in this ... for both physical and psychological problems. About Compulsive Exercise Compulsive exercise (also called obligatory exercise and anorexia ...

  19. Production of Ball-Lightning-Like Luminous Balls by Electrical Discharges in Silicon

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim, Jr.; Felisberto da Silva, Eronides, Jr.

    2007-01-01

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  20. Production of ball-lightning-like luminous balls by electrical discharges in silicon.

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim; da Silva, Eronides Felisberto

    2007-01-26

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  1. The ball SITE sign: Ball sports-induced targetoid erythema in a racquetball player.

    Science.gov (United States)

    Cohen, Philip R

    2015-07-01

    Cutaneous injury following impact of a high velocity ball to the skin may result in either erythema or purpura or both. The lesion typically appears as an annular ring of erythema with or without accompanying ecchymosis when the skin is contacted by a paintball, a ping pong ball, a racquetball or a squash ball. To describe a girl with targetoid erythema following impact of a racquetball on her flank and back and to review other sports associated with this response to skin injury. PubMed was used to search the following terms, separately and in combination: ball, erythema, paint, ping pong, purpura, racquetball, sign, site, sports, squash, targetoid. All papers were reviewed and relevant manuscripts, along with their reference citations, were evaluated. A 13-year-old girl developed an annular red ring surrounding a central area of normal appearing skin on her right flank and upper back where a racquetball traveling at a high velocity contacted her skin. Similar appearing lesions of targetoid erythema have been described at the cutaneous impact sites of either paintballs, ping pong balls, squash balls; in addition to erythema, purpura may also concurrently appear or subsequently develop at the contact location of the ball with the skin. Targetoid erythema is a pathognomonic cutaneous presentation resulting from the impact of either a paintball, ping pong ball, racquetball or squash ball-that is traveling at a high velocity-with a sport participant's skin. The ball SITE (sports-induced targetoid erythema) sign is suggested as a unifying nomenclature to designate this unique, ball sport-associated, cutaneous dermatosis in athletes participating in sports in which high velocity impact of the ball with the skin may occur.

  2. How Magnus Bends the Flying Ball--Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-01-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways,…

  3. Flexible timing of eye movements when catching a ball.

    Science.gov (United States)

    López-Moliner, Joan; Brenner, Eli

    2016-01-01

    In ball games, one cannot direct ones gaze at the ball all the time because one must also judge other aspects of the game, such as other players' positions. We wanted to know whether there are times at which obtaining information about the ball is particularly beneficial for catching it. We recently found that people could catch successfully if they saw any part of the ball's flight except the very end, when sensory-motor delays make it impossible to use new information. Nevertheless, there may be a preferred time to see the ball. We examined when six catchers would choose to look at the ball if they had to both catch the ball and find out what to do with it while the ball was approaching. A catcher and a thrower continuously threw a ball back and forth. We recorded their hand movements, the catcher's eye movements, and the ball's path. While the ball was approaching the catcher, information was provided on a screen about how the catcher should throw the ball back to the thrower (its peak height). This information disappeared just before the catcher caught the ball. Initially there was a slight tendency to look at the ball before looking at the screen but, later, most catchers tended to look at the screen before looking at the ball. Rather than being particularly eager to see the ball at a certain time, people appear to adjust their eye movements to the combined requirements of the task.

  4. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  5. Energy transfer problems of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egely, G.

    1986-04-01

    The paper analyzes the energy transport phenomenon of ball lightnings, but momentum and charge transport phenomena are considered as well. The physical properties as energy density and transfer are investigated using several observers' accounts of interactions with different objects. It is shown that contrary to previous assumptions the ball lightning has negative electric charge, and very high internal energy density. Both internal and external energy source models are analyzed, and it is shown that regardless to the details of a given model neither of them can explain actual observations. This has been validated by a well documented case study, and by several additional observations. An entirely new, testable model is suggested, which is able to stand for all observed properties of ball lightnings, and it explains the cause of rarity of ball lightnings, and the reasons of the unsuccessful experimental efforts. It is shown that the plasma sphere is just a visible side effect of a more important phenomenon.

  6. Crystal ball single event display

    International Nuclear Information System (INIS)

    Grosnick, D.; Gibson, A.; Allgower, C.; Alyea, J.; Argonne National Lab., IL

    1997-01-01

    The Single Event Display (SED) is a routine that is designed to provide information graphically about a triggered event within the Crystal Ball. The SED is written entirely in FORTRAN and uses the CERN-based HICZ graphing package. The primary display shows the amount of energy deposited in each of the NaI crystals on a Mercator-like projection of the crystals. Ten different shades and colors correspond to varying amounts of energy deposited within a crystal. Information about energy clusters is displayed on the crystal map by outlining in red the thirteen (or twelve) crystals contained within a cluster and assigning each cluster a number. Additional information about energy clusters is provided in a series of boxes containing useful data about the energy distribution among the crystals within the cluster. Other information shown on the event display include the event trigger type and data about π o 's and η's formed from pairs of clusters as found by the analyzer. A description of the major features is given, along with some information on how to install the SED into the analyzer

  7. Middle finger and ball movements around ball release during baseball fastball pitching.

    Science.gov (United States)

    Matsuo, Tomoyuki; Jinji, Tsutomu; Hirayama, Daisaku; Nasu, Daiki; Ozaki, Hiroki; Kumagawa, Daisuke

    2017-02-28

    The objectives of this study were to investigate middle finger movements and dynamics of ball movements around the instant of ball release during baseball pitching. Baseball pitching from an indoor mound among 14 semi-professional pitchers was captured using a motion capture system with 16 high-speed cameras (1,000 Hz). Kinematics of middle finger joints, ball rotation, and force applied to the ball were calculated. The proximal and distal interphalangeal joints continued to extend until the instant of ball release, then abruptly flexed. The abrupt flexion lasted for only several milliseconds, followed by a short extension phase. The finger made a quick double cycle of extension-flexion movement, suggesting that it attained high stiffness resulting from co-contraction. The ball began to roll up to the tip of the finger 8 ± 1 ms before ball release owing to the start of extension or the increased angular velocity of extension for the proximal interphalangeal joint. A mean force of 195 ± 27 N was applied in the proximal direction of the hand at the same time as the beginning of ball rolling, and a mean force of 109 ± 22 N was applied to the throwing direction just before ball release.

  8. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Thermoelastoplastic Deformation of a Multilayer Ball

    Science.gov (United States)

    Murashkin, E. V.; Dats, E. P.

    2017-09-01

    The problem of centrally symmetric deformation of a multilayer elastoplastic ball in the process of successive accretion of preheated layers to its outer surface is considered in the framework of small elastoplastic deformations. The problems of residual stress formation in the elastoplastic ball with an inclusion and a cavity are solved under various mechanical boundary conditions on the inner surface and for prescribed thermal compression distributions. The graphs of residual stress and displacement fields are constructed.

  10. Effects of bushings characteristics on suspension ball joint travels

    Science.gov (United States)

    Yang, Xiaobo

    2011-02-01

    In this paper, a short-long arm type front suspension is represented using multi-body dynamics model established with ADAMS®, where the suspension bushings modelled as linear and nonlinear elements, respectively, are integrated with a flexible cradle and other suspension components. A ball joint travel, defined as the angular displacement between the two parts connected with the ball joint, is calculated, where the measured wheel loads and spindle accelerations from a proving ground severe durability test schedule serve as the input data. The ball joints considered in this study include lower ball joints, upper ball joints, outer tierod ball joints, and inner tierod ball joints. The results clearly illustrate that the bushing stiffness and nonlinearity are important for an accurate prediction of ball joint travels and the ball joint travel sensitivities to considered design variables are important for engineers to understand and ensure reliable designs of ball joints.

  11. Secret of a ball lightning

    OpenAIRE

    Савич, Эдуард Владимирович

    2013-01-01

    Шаровая молния – явление природы, происходящее при ударе линейной молнии с ее воздействием тепловой и магнитной энергии, возникающей вокруг канала линейной молнии и в результате образующей из окружающего воздуха облако пара, переходящего под воздействием магнитного поля сегнетоэлектрическое состояние. A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming...

  12. Birth rights.

    Science.gov (United States)

    Hawkin, R

    1980-06-01

    Despite the marked decline in Singapore's crude birth rate from 42.7/1000 population to 22.1/1000 population from 1957 to 1970, the government adopted a policy of sterilization by coercion with the passage in 1970 of the Voluntary Sterilisation Act. Although sterilization is supposedly voluntary, various regulations make it extremely difficult for couples who wish to retain their fertility. Couples under 40 years of age with more than 2 children must agree to accept sterilization or their children are assigned to a low priority category in regard to primary school admittance. An individual who wishes to marry a non-Singaporean cannot obtain a marriage application unless one of the parties to the marriage agrees to have a sterilization after the birth of their 2nd child. Singapore, with a population density of almost 4000/square kilometer, needs to be concerned about population growth; however, since the population had for the most part already adopted a 2 child family norm, these coercive policies appear to be blatantly excessive.

  13. Effect of a ball skill intervention on children's ball skills and cognitive functions

    NARCIS (Netherlands)

    Westendorp-Haverdings, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    Purpose: This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning

  14. Keeping Your Eyes Continuously on the Ball While Running for Catchable and Uncatchable Fly Balls

    NARCIS (Netherlands)

    Postma, Dees B. W.; den Otter, A. Rob; Zaal, Frank T. J. M.

    2014-01-01

    When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its

  15. Aerodynamic drag of modern soccer balls.

    Science.gov (United States)

    Asai, Takeshi; Seo, Kazuya

    2013-12-01

    Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10(5) (drag coefficient, C d  ≈ 0.12), ~2.8 × 10(5) (C d  ≈ 0.13), ~3.3 × 10(5) (C d  ≈ 0.13), and ~2.4 × 10(5) (C d  ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces.

  16. The influence of different exercise intensities on kicking accuracy and velocity in soccer players

    Directory of Open Access Journals (Sweden)

    Ricardo Ferraz

    2017-12-01

    Conclusion: These findings suggest that kicking ball velocity is influenced by high-exercise intensities. Low and moderate exercise intensities do not affect the performance of the kick, and intensity does not influence accuracy. Otherwise, it is possible that other mechanisms (not only physiological may influence players during the exercise.

  17. Effect of a ball skill intervention on children's ball skills and cognitive functions.

    Science.gov (United States)

    Westendorp, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    2014-02-01

    This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning disorders. Ninety-one children with learning disorders (age 7-11 yr old) were recruited from six classes in a Dutch special-needs primary school. The six classes were assigned randomly either to the intervention or to the control group. The control group received the school's regular physical education lessons. In the intervention group, ball skills were practiced in relative static, simple settings as well as in more dynamic and cognitive demanding settings. Both groups received two 40-min lessons per week. Children's scores on the Test of Gross Motor Development-2 (ball skills), Tower of London (problem solving), Trail Making Test (cognitive flexibility), Dutch Analysis of Individual Word Forms (reading), and the Dutch World in Numbers test (mathematics) at pretest, posttest, and retention test were used to examine intervention effects. The results showed that the intervention group significantly improved their ball skills, whereas the control group did not. No intervention effects were found on the cognitive parameters. However, within the intervention group, a positive relationship (r = 0.41, P = 0.007) was found between the change in ball skill performance and the change in problem solving: the larger children's improvement in ball skills, the larger their improvement in problem solving. The present ball skill intervention is an effective instrument to improve the ball skills of children with learning disorders. Further research is needed to examine the effect of the ball skill intervention on the cognitive parameters in this population.

  18. Novel mathematical model to estimate ball impact force in soccer.

    Science.gov (United States)

    Iga, Takahito; Nunome, Hiroyuki; Sano, Shinya; Sato, Nahoko; Ikegami, Yasuo

    2017-11-22

    To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of 'footballer's ankle'. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.

  19. Laser Sintering Technology and Balling Phenomenon.

    Science.gov (United States)

    Oyar, Perihan

    2018-02-01

    The aim of this review was to evaluate the balling phenomenon which occurs typically in Selective Laser Sintering (SLS). The balling phenomenon is a typical SLS defect, and observed in laser sintered powder, significantly reduces the quality of SLS, and hinders the further development of SLS Technology. Electronic database searches were performed using Google Scholar. The keywords "laser sintering, selective laser sintering, direct metal laser melting, and balling phenomenon" were searched in title/abstract of publications, limited to December 31, 2016. The inclusion criteria were SLS, balling phenomenon, some alloys (such as Cr-Co, iron, stainless steel, and Cu-based alloys) mechanical properties, microstructure and bond strength between metal-ceramic crown, laboratory studies, full text, and in English language. A total of 100 articles were found the initial search and yielded a total of 50 studies, 30 of which did not fulfill the inclusion criteria and were therefore excluded. In addition, 20 studies were found by screening the reference list of all included publications. Finally, 40 studies were selected for this review. The method in question is regulated by powder material characteristics and the conditions of laser processing. The procedure of formation, affecting factors, and the mechanism of the balling effect are very complex.

  20. Electrostatic charge bounds for ball lightning models

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Karl D [Department of Technology, Texas State University, San Marcos, TX 78666 (United States)], E-mail: kdstephan@txstate.edu

    2008-03-15

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  1. Electrostatic charge bounds for ball lightning models

    Science.gov (United States)

    Stephan, Karl D.

    2008-03-01

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  2. Relativistic-microwave theory of ball lightning

    Science.gov (United States)

    Wu, H.-C.

    2016-06-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  3. On the energy characteristics of ball lightning.

    Science.gov (United States)

    Bychkov, A V; Bychkov, V L; Abrahamson, John

    2002-01-15

    A compilation of 17 observations of ball lightning showing the most energetic effects is presented along with estimates of their energy content. These observations were chosen from several thousand for the much stronger interaction of each ball lightning on its surroundings, and the method of energy estimation outlined. The case is put that some of the observations show a higher energy than self-contained chemical energy could provide. Comments have been added to the paper, arguing that the energy estimations themselves should be consistent with whatever model is used for ball lightning. For example, the presence of reacting nanoparticles releasing chemical energy may bring about the same observed effects with lower estimated energy.

  4. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-06-22

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  5. On longevity of I-ball/oscillon

    Energy Technology Data Exchange (ETDEWEB)

    Mukaida, Kyohei [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Takimoto, Masahiro [Theory Center, KEK,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel); Yamada, Masaki [Institute of Cosmology, Department of Physics and Astronomy, Tufts University,Medford, MA 02155 (United States); Department of Physics, Tohoku University,Sendai, Miyagi 980-8578 (Japan)

    2017-03-23

    We study I-balls/oscillons, which are long-lived, quasi-periodic, and spatially localized solutions in real scalar field theories. Contrary to the case of Q-balls, there is no evident conserved charge that stabilizes the localized configuration. Nevertheless, in many classical numerical simulations, it has been shown that they are extremely long-lived. In this paper, we clarify the reason for the longevity, and show how the exponential separation of time scales emerges dynamically. Those solutions are time-periodic with a typical frequency of a mass scale of a scalar field. This observation implies that they can be understood by the effective theory after integrating out relativistic modes. We find that the resulting effective theory has an approximate global U(1) symmetry reflecting an approximate number conservation in the non-relativistic regime. As a result, the profile of those solutions is obtained via the bounce method, just like Q-balls, as long as the breaking of the U(1) symmetry is small enough. We then discuss the decay processes of the I-ball/oscillon by the breaking of the U(1) symmetry, namely the production of relativistic modes via number violating processes. We show that the imaginary part is exponentially suppressed, which explains the extraordinary longevity of I-ball/oscillon. In addition, we find that there are some attractor behaviors during the evolution of I-ball/oscillon that further enhance the lifetime. The validity of our effective theory is confirmed by classical numerical simulations. Our formalism may also be useful to study condensates of ultra light bosonic dark matter, such as fuzzy dark matter, and axion stars, for instance.

  6. Soccer ball lift coefficients via trajectory analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2010-07-15

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.

  7. Birth control pills - combination

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000655.htm Birth control pills - combination To use the sharing features ... contain both progestin and estrogen. What Are Combination Birth Control Pills? Birth control pills help keep you ...

  8. Birth Control Explorer

    Science.gov (United States)

    ... Relationships STIs Media Facebook Twitter Tumblr Shares · 582 Birth Control Explorer Sort by all methods most effective ... MORE You are here Home » Birth Control Explorer Birth Control Explorer If you’re having sex —or ...

  9. Accredited Birth Centers

    Science.gov (United States)

    ... Administrative Staff Donate Contact MENU CLOSE back Accredited Birth Centers You are here: Home Accredited Birth Centers ... not CABC-accredited. How do you find a birth center here? Skip Instructions! Get to the Map… ...

  10. Essure Permanent Birth Control

    Science.gov (United States)

    ... and Prosthetics Essure Permanent Birth Control Essure Permanent Birth Control Share Tweet Linkedin Pin it More sharing ... Email Print Essure is a a permanently implanted birth control device for women (female sterilization). Implantation of ...

  11. Warning Signs After Birth

    Science.gov (United States)

    ... care > Warning signs after birth Warning signs after birth E-mail to a friend Please fill in ... health problems new moms may have after giving birth? Chances are that you’ll be healthy after ...

  12. CDC WONDER: Births

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Births (Natality) online databases in CDC WONDER report birth rates, fertility rates and counts of live births occurring within the United States to U.S....

  13. Health Instruction Packages: Consumer--Birth Control.

    Science.gov (United States)

    Pries, Rose Mary; And Others

    Designed for the general public, these three learning modules utilize text, illustrations, and exercises to describe various methods of birth control. The first module, "All about Contraception for the Teenage New Mother" by Rose Mary Pries, discusses the desirability of planned pregnancy and reviews the effectiveness and side effects of…

  14. Birth Weight does not Associate with Gestational Physical Activity ...

    African Journals Online (AJOL)

    Exercise during pregnancy has been a subject of debate and whether gestational physical activity profile affects birth weight is an important issue as birth weight is an indicator of fetal, neo-natal and post-natal mortality. This study was carried at three hospitals in Enugu, Eastern Nigeria to determine the difference between ...

  15. Paddle Angle and Ball Spin in Table Tennis

    Directory of Open Access Journals (Sweden)

    Binvant Broca

    2017-01-01

    Full Text Available The relationship between the impact angle of a table tennis ball with respect to the paddle and angular velocity of the ball leaving the paddle was investigated. A table tennis ball was dropped onto a paddle oriented at impact angles ranging from 10° to 80°. It was found that the sine of the impact angle is proportional to the angular velocity of the ball as it leaves the paddle for all impact angles tested.

  16. Contraception and Birth Control

    Science.gov (United States)

    ... Facebook Twitter Pinterest Email Print About Contraception and Birth Control Contraception is the prevention of pregnancy. Contraception, or birth control, also allows couples to plan the timing ...

  17. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    theory of computation, logic, and linear algebra. He has authored three books in these areas. We present a ball game that can be continued as long as we wish. It looks as though the game would never end. But by applying a result on trees, we show that the game nonetheless ends in some finite number of moves. We then ...

  18. On the dynamics of ball bearings

    NARCIS (Netherlands)

    Wensing, J.A.

    1998-01-01

    This investigation on the dynamic behaviour of ball bearings was motivated by the demand for silent bearings in noise-sensitive applications, especially in the household appliance and automotive industry. The present investigations are intended to provide a clear understanding of the role of the

  19. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    We present a ball game that can be continued as long as wewish. It looks as though the game would never end. But byapplying a result on trees, we show that the game nonethelessends in some finite number of moves. We then point out somedeep results on the natural number system connected withthe game.

  20. Computed Tomography Analysis of NASA BSTRA Balls

    Energy Technology Data Exchange (ETDEWEB)

    Perry, R L; Schneberk, D J; Thompson, R R

    2004-10-12

    Fifteen 1.25 inch BSTRA balls were scanned with the high energy computed tomography system at LLNL. This system has a resolution limit of approximately 210 microns. A threshold of 238 microns (two voxels) was used, and no anomalies at or greater than this were observed.

  1. Renal fungus ball: a challenging clinical problem.

    Science.gov (United States)

    Tan, Wei Phin; Turba, Ulku C; Deane, Leslie A

    2017-04-28

    We describe a case of renal pelvi-ureteric fungus ball managed with placement of two nephrostomy tubes and amphotericin B irrigation through a nephrostomy tube with the other to free drain. A 46-year-old man with uncontrolled Type 2 diabetes mellitus was referred to the urology clinic for workup of recurrent urinary tract infection. Urine culture grew Candida albicans. The patient was started on oral fluconazole therapy. Cystoscopy and cystogram revealed a grade 3 left vesicoureteral reflux and right retrograde pyelogram revealed a filling defect in the right renal pelvis extending into the proximal ureter with severe hydroureteronephrosis. Two nephrostomy tubes were placed (mid-pole and lower pole) to ensure that the system was not obstructed. Amphotericin B (50 mg/1000 ml normal saline) irrigation was then instilled through the mid-pole nephrostomy tube at a rate of 30 ml/h with the lower pole nephrostomy tube to free drain. An antegrade nephrostogram was performed after 5 days of amphotericin B instillation, showing complete resolution of the fungus ball. The patient is awaiting definitive minimally invasive management of the distal ureteral narrowing. Renal and pelvi-ureteric fungus ball is a challenging clinical entity. It must be addressed promptly and efficiently to be successful. We describe a minimally invasive approach that was tolerated well and resulted in complete clearance of the fungus ball in a relatively short time frame.

  2. 4 π physics with the plastic ball

    International Nuclear Information System (INIS)

    Gutbrod, H.H.; Loehner, H.; Poskanzer, A.M.; Renner, T.; Riedesel, H.; Ritter, H.G.; Warwick, A.; Weik, F.; Wieman, H.

    1982-10-01

    4 π data taken with the Plastic Ball show that cluster production in relativistic nuclear collisions depends on both the size of the participant volume and the finite size of the cluster. The measurement of the degree of thermalization and the search for collective flow will permit the study of the applicability of macroscopic concepts such as temperature and density

  3. Tennis Ball Flight under Strong Wind

    Indian Academy of Sciences (India)

    playing tennis ball cricket or soccer. So go out, play, learn and kick up some dust. But, make sure it does not boomerang in your face! Hurry up before television and third umpires corrupt this great IndIan pastime. Dedication: This article is dedicated to the memory of. Indian cricket legend M L Jaisimha (1939-1999).

  4. A plasma ball in the Microcosm museum

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Plasma balls, like the one shown here, are displayed in the Microcosm exhibition where families can visit to learn more about the experiments carried out in a research institute like CERN. Hands-on activities allow visitors to get a step closer to the research activities carried out at CERN.

  5. Interrelation between ball lightning and optically induced forces

    Science.gov (United States)

    Torchigin, V. P.; Torchigin, A. V.

    2013-09-01

    Optically induced forces are considered as a key factor for explaining the phenomenon of ball lightning. They can provide not only the existence of ball lightning in the form of self-confined intense white light circulating in a spherical shell of air strongly compressed by the light but also the anomalous motion of ball lightning in the terrestrial atmosphere.

  6. Entry Times Distribution for Dynamical Balls on Metric Spaces

    Science.gov (United States)

    Haydn, N.; Yang, F.

    2017-04-01

    We show that the entry and return times for dynamical balls (Bowen balls) is exponential for systems that have an α -mixing invariant measure with certain regularities. We also show that systems modeled by Young's tower has exponential entry time distribution for dynamical balls. We also apply the results to conformal maps and expanding maps on the interval.

  7. Flexible timing of eye movements when catching a ball

    NARCIS (Netherlands)

    López-Moliner, Joan; Brenner, Eli

    2016-01-01

    In ball games, one cannot direct ones gaze at the ball all the time because one must also judge other aspects of the game, such as other players' positions. We wanted to know whether there are times at which obtaining information about the ball is particularly beneficial for catching it. We recently

  8. Temperature and Coefficient of Restitution of a Table Tennis Ball

    Directory of Open Access Journals (Sweden)

    Yoonyoung Chang

    2016-01-01

    Full Text Available The coefficient of restitution (COR of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  9. Validity and Reliability of a Medicine Ball Explosive Power Test.

    Science.gov (United States)

    Stockbrugger, Barry A.; Haennel, Robert G.

    2001-01-01

    Evaluated the validity and reliability of a medicine ball throw test to evaluate explosive power. Data on competitive sand volleyball players who performed a medicine ball throw and a standard countermovement jump indicated that the medicine ball throw test was a valid and reliable way to assess explosive power for an analogous total-body movement…

  10. Temperature and Coefficient of Restitution of a Table Tennis Ball

    OpenAIRE

    Yoonyoung Chang

    2016-01-01

    The coefficient of restitution (COR) of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  11. Energy density calculations for ball-lightning-like luminous silicon balls

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Gerson S; Ferreira, Joacy V; Bastos, Cristiano C; Dos Santos, Marcus V; Pavao, Antonio C [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Pernambuco (Brazil)

    2010-05-11

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m{sup -3}, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model. (methodological notes)

  12. METHODOLOGICAL NOTES: Energy density calculations for ball-lightning-like luminous silicon balls

    Science.gov (United States)

    Paiva, Gerson S.; Ferreira, Joacy V.; Bastos, Cristiano C.; dos Santos, Marcus V.; Pavão, Antonio C.

    2010-05-01

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m-3, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model.

  13. Neutrons and the crystal ball experiments

    International Nuclear Information System (INIS)

    Alyea, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H.; Stanislaus, S.

    1997-01-01

    The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4π st (20 degree le θ le 160degree and 0degree le φ le 360degree) from the center. The Crystal Ball detector was used for two long series of experiments at the e + e - colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include π - pr a rrow neutrals with pion beam momenta approximately400-750 MeV/c and K - pr a rrow neutrals with kaon beam momenta approximately600-750 MeV/c. Each of these reactions will include a neutron in the final state. whereas the fraction of e + e - interactions with neutrons at SLAC or DESY was quite small. Consequently, there is relatively little experience understanding the behavior of neutrons in the Crystal Ball

  14. Prevention: Exercise

    Medline Plus

    Full Text Available ... ball directly in front of you. Keep your abdominal muscles tight and feet flat on the floor; rotate ... with your back to the wall). Tighten your abdominal muscles, then reach through your legs to touch the ...

  15. Prevention: Exercise

    Medline Plus

    Full Text Available ... A SPECIALIST Prevention Strengthening Exercise Committee Exercise Committee Core Strengthening Many popular forms of exercise focus on ... acute pain, you should stop doing it. Transverse Core Strengthening This strengthens the muscles that cross from ...

  16. Prevention: Exercise

    Medline Plus

    Full Text Available ... Your Core! Stretching/Flexibility Aerobic Exercise Cervical Exercise Strength Training for the Elderly Other Back Pack Safety Pregnancy ... 15 repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing ...

  17. Apparatus and method for inspecting a bearing ball

    Science.gov (United States)

    Bankston, B. F. (Inventor)

    1985-01-01

    A method and apparatus for inspecting the surface of a ball bearing is disclosed which includes a base having a high friction non-abrasive base scanning surface. A holding device includes a cone-shaped cup recess in which a ball element is received. Air is introduced through a passage to relieve friction between the wall of the recess and the ball element and facilitate rolling of the ball over the high friction base surface. The holding device is moved over the base scanning surface in a predetermined pattern such that the entire surface of the ball element is inspected byan eddy current probe which detects any surface defects.

  18. Comparative study of muscle strengthening exercises for treatment of chronic low backache

    OpenAIRE

    Soumya Ghosh; Soma Datta; Suravi Nayak; Arunima Chaudhuri; Pitchai Dhanasekaran

    2014-01-01

    Background: Low back pain is a major cause of musculoskeletal disability worldwide. Objectives: To study the outcomes of different muscle strengthening exercises in treatment of low back pain Materials and Methods: One hundred and twenty patients in the age group of 20-40 years with mechanical low back pain were randomly divided intotwo groups and instructed to perform two different types of exercises for three months (Mckenzie exercise andSwiss ball exercise). Patients were assessed by Visua...

  19. Aerodynamic effects of dimples on soccer ball surfaces.

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2017-10-01

    Recently, the shape and design of the panel on the official ball used in the FIFA World Cup was considerably different from that of a conventional soccer ball (having 32 pentagonal and hexagonal panels). Depending on the number of different panels and their orientation, the aerodynamic force experienced by a ball is believed to change, which in turn changes the ball trajectory. However, not much is known about the impact of the surface forms of a ball on its aerodynamics. Therefore, in the present study, 10 different types of soccer balls were produced and their aerodynamic properties were studied by wind tunnel experiments. The results confirmed that the aerodynamic force acting on the ball varied considerably depending on the existence of dimples on the ball surface. In addition, the 4 types of soccer balls, which had different kinds of roughness, revealed that even balls having the same number and shapes of panels experienced greatly varying aerodynamic forces depending on the surface form of the balls.

  20. The strange flight behaviour of slowly spinning soccer balls

    Science.gov (United States)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-05-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

  1. Prevention: Exercise

    Medline Plus

    Full Text Available ... Injections PREVENTION Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/Flexibility Aerobic Exercise ...

  2. Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

    Directory of Open Access Journals (Sweden)

    Jan Carboch, Vladimir Süss, Tomas Kocib

    2014-06-01

    Full Text Available Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server. Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing.

  3. Casimir Energies for Isorefractive or Diaphanous Balls

    Directory of Open Access Journals (Sweden)

    Kimball A. Milton

    2018-03-01

    Full Text Available It is known that the Casimir self-energy of a homogeneous dielectric ball is divergent, although a finite self-energy can be extracted through second order in the deviation of the permittivity from the vacuum value. The exception occurs when the speed of light inside the spherical boundary is the same as that outside, so the self-energy of a perfectly conducting spherical shell is finite, as is the energy of a dielectric-diamagnetic sphere with ε μ = 1 , a so-called isorefractive or diaphanous ball. Here we re-examine that example and attempt to extend it to an electromagnetic δ -function sphere, where the electric and magnetic couplings are equal and opposite. Unfortunately, although the energy expression is superficially ultraviolet finite, additional divergences appear that render it difficult to extract a meaningful result in general, but some limited results are presented.

  4. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    tree is a tree in which each node has a finite number of children. In a rooted tree, the sequence of nodes from the root to a leaf, where the (j + 1)th node is a child of the jth node, is called a. 'path'. For instance, in the above tree, the root contains 2, and all leafs are the nodes that contain 0. Since any ball is replaced with a fi-.

  5. Free-floating atmospheric pressure ball plasmas

    Science.gov (United States)

    Wurden, G. A.; Ticos, C.; Wang, Z.; Wurden, C. J. V.

    2007-11-01

    A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with a weak solution of various salts in distilled water, such as CuSO4 or CuCl2, LiCl or NaCl). An underwater ring anode completes the circuit. A bubble of hot vapor from the water surface rises up in the first few milliseconds, and changes from a mushroom cloud with stalk, to a detached quasi-spherical object, finally evolving into a vortex ring. The plasma consists of ionized water vapor, with positive salts and OH- radicals, as well as molecular species, and it completely excludes nitrogen or oxygen from the rising plasma structure. A fine boundary layer is visible in orange, in contrast to a green ball interior when using Cu/CuSO4, and filamentary structures are visible at late times. Finally, a whisp of smoke ring is observed as a residue. A variety of visible and infrared imaging (both video and still cameras) are used, along with 200-800 nm time & space resolved spectroscopy, to identify features of this laboratory analog to ball lightning. Possible applications include a windowless ball- plasma powered pulsed copper vapor laser operating at 510 nm.

  6. Relativistic-microwave theory of ball lightning

    OpenAIRE

    H.-C. Wu

    2016-01-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by partic...

  7. Testing general relativity using a bouncing ball

    Directory of Open Access Journals (Sweden)

    Shiuan-Ni Liang

    2014-01-01

    Full Text Available In a recent article (Liang and Lan, (2011, we showed that the trajectories predicted by general-relativistic and Newtonian mechanics from the same parameters and initial conditions for a low-speed weak-gravity bouncing ball system will rapidly disagree completely if the trajectories are chaotic. Here, we determine how accurate the parameters and initial conditions of the system must be known so that the two different calculated chaotic trajectories are sufficiently accurate for an empirical test.

  8. Ball-thrower's fracture of the humerus

    International Nuclear Information System (INIS)

    Callaghan, Eric B.; Bennett, D. Lee; El-Khoury, Georges Y.; Ohashi, Kenjirou

    2004-01-01

    A relatively rare case of ball-thrower's fracture of the humerus is presented. Severe muscular action is an uncommon cause of humeral fractures but has been well documented in the orthopedic literature. To our knowledge, this fracture has not been described in the radiology literature, and awareness of this entity could preclude further unnecessary workup. The mechanism of injury and its typical radiographic appearance is described. (orig.)

  9. Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory

    Directory of Open Access Journals (Sweden)

    Inaba Yuki

    2017-01-01

    Full Text Available The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

  10. Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory.

    Science.gov (United States)

    Inaba, Yuki; Tamaki, Sho; Ikebukuro, Haruhiko; Yamada, Koshi; Ozaki, Hiroki; Yoshida, Kazuto

    2017-01-01

    The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

  11. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  12. Searching for Q-balls with HAWC

    Science.gov (United States)

    Karn, Peter

    2013-04-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray experiment currently under construction at Sierra Negra in the state of Puebla, Mexico. Once completed, it will consist of a 20,000 square meter array of 300 water Cherenkov detectors. Although the HAWC Observatory is designed to study gamma rays from galactic and extra-galactic sources, the large instrumented volume of water gives the opportunity to search for more exotic species. One such target, predicted by several varieties of supersymmetric theory, is the Q-ball. Q-balls are very massive, sub-relativistic particles that can have a large baryon number, and can be stable since their creation in the early universe. They are also an appealing candidate for the dark matter of the universe, but their large masses must mean that their flux is very low. The data acquisition system of the HAWC Observatory is flexible enough that, with a dedicated trigger algorithm for non-relativistic particles, it allows the search for Q-balls traversing the detector. The trigger algorithm and preliminary analysis will be presented.

  13. 3D Printing of Ball Grid Arrays

    Science.gov (United States)

    Sinha, Shayandev; Hines, Daniel; Dasgupta, Abhijit; Das, Siddhartha

    Ball grid arrays (BGA) are interconnects between an integrated circuit (IC) and a printed circuit board (PCB), that are used for surface mounting electronic components. Typically, lead free alloys are used to make solder balls which, after a reflow process, establish a mechanical and electrical connection between the IC and the PCB. High temperature processing is required for most of these alloys leading to thermal shock causing damage to ICs. For producing flexible circuits on a polymer substrate, there is a requirement for low temperature processing capabilities (around 150 C) and for reducing strain from mechanical stresses. Additive manufacturing techniques can provide an alternative methodology for fabricating BGAs as a direct replacement for standard solder bumped BGAs. We have developed aerosol jet (AJ) printing methods to fabricate a polymer bumped BGA. As a demonstration of the process developed, a daisy chain test chip was polymer bumped using an AJ printed ultra violet (UV) curable polymer ink that was then coated with an AJ printed silver nanoparticle laden ink as a conducting layer printed over the polymer bump. The structure for the balls were achieved by printing the polymer ink using a specific toolpath coupled with in-situ UV curing of the polymer which provided good control over the shape, resulting in well-formed spherical bumps on the order of 200 um wide by 200 um tall for this initial demonstration. A detailed discussion of the AJ printing method and results from accelerated life-time testing will be presented

  14. Modeling on the Effect of Coal Loads on Kinetic Energy of Balls for Ball Mills

    Directory of Open Access Journals (Sweden)

    Yan Bai

    2015-07-01

    Full Text Available This paper presents a solution for the detection and control of coal loads that is more accurate and convenient than those currently used. To date, no research has addressed the use of a grinding medium as the controlled parameter. To improve the accuracy of the coal load detection based on the kinetic energy of balls in a tubular ball mill, a Discrete Element Method (DEM model for ball kinematics based on coal loads is proposed. The operating process for a ball mill and the ball motion, as influenced by the coal quality and the coal load, was analyzed carefully. The relationship between the operating efficiency of a coal pulverizing system, coal loads, and the balls’ kinetic energy was obtained. Origin and Matlab were utilized to draw the variation of parameters with increasing coal loads in the projectile and cascading motion states. The parameters include the balls’ real-time kinetic energy, the friction energy consumption, and the mill’s total work. Meanwhile, a method of balanced adjacent degree and a physical experiment were proposed to verify the considerable effect of the balls’ kinetic energy on coal loads. The model and experiment results indicate that a coal load control method based on the balls’ kinetic energy is therefore feasible for the optimized operation of a coal pulverizing system.

  15. The nonlinear and ball pass effects of a ball bearing on rotor vibration

    International Nuclear Information System (INIS)

    Han, D. C.; Choi, S. H.; Lee, Y. H.; Kim, K. H.

    1998-01-01

    A ball bearing is generally assumed as a linear spring in rotor dynamic analysis. In real case, the force equilibrium of the bearing is changed as the relative position of each ball with respect to the direction of radial force. So, the stiffness of the bearing is also changed and is a function of time and position. In this study, the nonlinear characteristics of a ball bearing are considered in analyzing the vibration response of a rotating shaft due to an unbalance force. A finite element method is used to analyze the vibration characteristics of a rotor-bearing system and a direct numerical integration is performed to calculate the transient response of the rotor system. The responses are converted to the frequency domain and the effects of the parametric excitation due to a ball bearing are examined. The test rig for the investigation of the effect of a ball bearing on the rotor vibration is set up and the results are compared with those of numerical calculation. The calculation results show that the amplitudes of the nonlinear model are larger than those of the linear one. The frequencies of the calculations can be matched to the measured frequencies

  16. Relation Between Hertz Stress-Life Exponent, Ball-Race Conformity, and Ball Bearing Life

    Science.gov (United States)

    Zaretsky, Erwin V.; Poplawski, Joseph V.; Root, Lawrence E.

    2008-01-01

    ANSI/ABMA and ISO standards based on Lundberg-Palmgren bearing life theory are normalized for ball bearings having inner- and outerrace conformities of 52 percent (0.52) and made from pre-1940 bearing steel. The Lundberg-Palmgren theory incorporates an inverse 9th power relation between Hertz stress and fatigue life for ball bearings. The effect of race conformity on ball set life independent of race life is not incorporated into the Lundberg-Palmgren theory. In addition, post-1960 vacuum-processed bearing steel exhibits a 12th power relation between Hertz stress and life. The work reported extends the previous work of Zaretsky, Poplawski, and Root to calculate changes in bearing life--that includes the life of the ball set--caused by race conformity, Hertz stress-life exponent, ball bearing type and bearing series. The bearing fatigue life in actual application will usually be equal to or greater than that calculated using the ANSI/ABMA and ISO standards that incorporate the Lundberg-Palmgren theory. The relative fatigue life of an individual race is more sensitive to changes in race conformity for Hertz stress-life exponent n of 12 than where n = 9. However, when the effects are combined to predict actual bearing life for a specified set of conditions and bearing geometry, the predicted life of the bearing will be greater for a value of n = 12 than n = 9.

  17. Efficiency of application of special exercises and exercises with the use of baseball pitching machine

    Directory of Open Access Journals (Sweden)

    Agapov D.V.

    2012-01-01

    Full Text Available Efficiency of the approach on making up coordination capabilities and technical tactical performances in baseball is confirmed. 100 boys (age 12-14 years take part in experiment. Relative analysis of a level of development of coordination capabilities and technical tactical readiness of baseball players is carried out. The level of development of technical readiness after experiment under the program «pitch, hit and run» is taped. The frame of special exercises with usage of colour balls is featured. Dynamics of hits for baseball players on a flying ball is presented. The approach in modelling of requirements of competitive activity is developed.

  18. Why Exercise?

    Science.gov (United States)

    ... do I have to exercise to gain health benefits? Even small amounts of exercise are better than none at all. Start with ... As you become used to exercising, try to exercise within your target heart rate zone so that you get the most benefit. To take your pulse, gently rest 2 fingers ...

  19. Sitting on stability balls: biomechanics evaluation in a workplace setting.

    Science.gov (United States)

    Schult, Tamara M; Awosika, Ebi R; Schmunk, Sandra K; Hodgson, Michael J; Heymach, Bria L; Parker, Celestine Dent

    2013-01-01

    Use of a stability ball alone and stability ball chair were evaluated in the Veterans Health Administration as possible alternatives to incorporate with regular office chair use. The evaluation of stability ball use was conducted under the auspices of a work site health promotion program as a cross-over trial with participants rotating through use of the stability ball, stability ball chair, and regular office chair on a monthly basis for a total duration of 3 months. Rotations on regular office chairs served as the control. Three medical facilities participated. A total of 193 employees completed a baseline questionnaire; 159 completed at least one post-rotation questionnaire. Self-reported measures included perceived posture when sitting, perceptions of overall balance, energy levels, job performance, safety, and pain. Use was associated with improvements in perceived posture (p balance (p = 0.05) for stability ball chair users compared with the control. Use of stability balls at work decreases the likelihood of reporting pain from regular office chair use from approximately 45% to 21%. Alternatively, a high number of participants reported pain with use of the stability ball alone and stability ball chair, 42% and 45%, respectively. The perceived risks and benefits of stability ball use should be weighed when incorporating use.

  20. Aerodynamics in the classroom and at the ball park

    Science.gov (United States)

    Cross, Rod

    2012-04-01

    Experiments suitable for classroom projects or demonstrations are described concerning the aerodynamics of polystyrene balls. A light ball with sufficient backspin can curve vertically upward through the air, defying gravity and providing a dramatic visual demonstration of the Magnus effect. A ball projected with backspin can also curve downward with a vertical acceleration greater than that due to gravity if the Magnus force is negative. These effects were investigated by filming the flight of balls projected in an approximately horizontal direction so that the lift and drag forces could be easily measured. The balls were also fitted with artificial raised seams and projected with backspin toward a vertical target in order to measure the sideways deflection over a known horizontal distance. It was found that (a) a ball with a seam on one side can deflect either left or right depending on its launch speed and (b) a ball with a baseball seam can also deflect sideways even when there is no sideways component of the drag or lift forces acting on the ball. Depending on the orientations of the seam and the spin axis, a sideways force on a baseball can arise either if there is rough patch on one side of the ball or if there is a smooth patch. A scuff ball with a rough patch on one side is illegal in baseball. The effect of a smooth patch is a surprising new observation.

  1. Automatic ball bar for a coordinate measuring machine

    Science.gov (United States)

    Jostlein, Hans

    1997-01-01

    An automatic ball bar for a coordinate measuring machine determines the accuracy of a coordinate measuring machine having at least one servo drive. The apparatus comprises a first and second gauge ball connected by a telescoping rigid member. The rigid member includes a switch such that inward radial movement of the second gauge ball relative to the first gauge ball causes activation of the switch. The first gauge ball is secured in a first magnetic socket assembly in order to maintain the first gauge ball at a fixed location with respect to the coordinate measuring machine. A second magnetic socket assembly secures the second gauge ball to the arm or probe holder of the coordinate measuring machine. The second gauge ball is then directed by the coordinate measuring machine to move radially inward from a point just beyond the length of the ball bar until the switch is activated. Upon switch activation, the position of the coordinate measuring machine is determined and compared to known ball bar length such that the accuracy of the coordinate measuring machine can be determined.

  2. Biomechanics of Heading a Soccer Ball: Implications for Player Safety

    Directory of Open Access Journals (Sweden)

    Charles F. Babbs

    2001-01-01

    Full Text Available To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established criteria for serious head injury from the motor vehicle crash literature. The results suggest heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player�s size, strength, and technique. Smaller youth players, because of their lesser body mass, are more at risk of potentially dangerous headers than are adults, even when using current youth size balls. Lower ball inflation pressure reduces risk of dangerous head accelerations. Lower pressure balls also have greater “touch” and “playability”, measured in terms of contact time and contact area between foot and ball during a kick. Focus on teaching proper technique, the re-design of age-appropriate balls for young players with reduced weight and inflation pressure, and avoidance of head contact with fast, rising balls kicked at close range can substantially reduce risk of subtle brain injury in players who head soccer balls.

  3. A general theory for ball lightning structure and light output

    Science.gov (United States)

    Morrow, R.

    2018-03-01

    A general theory for free-floating ball lightning is presented which unifies the phantom plasma ball theory involving the production of very little light, with theories for ball lightning involving light output produced by burning particles from the soil. The mechanism for the formation of plasma balls is shown to be quite general, producing very similar plasma balls independent of initial ion densities over four orders of magnitude. All that is required is an excess of positive ions in the initial ball of ions. The central plasma density after 1 s is shown to be the reciprocal of the ion neutralization coefficient for all cases, both analytically and computationally. Further, the plasma region has zero electric field in all cases. Surrounding the plasma ball is a sphere of positive ions moving away from the centre via their own space-charge field; this space-charge field, which is the same in all cases near the plasma ball, drives negative ions and negative particles towards the plasma centre. The connection with burning particle theories is the proposition that the burning particles are highly-charged which is very likely after a lightning strike. Burning negatively charged particles would be driven into the plasma ball region and trapped while any positively charged particles would be driven away. The plasma ball structure is shown to last more than 10 s and the ‘burnout time’ for a typical coal particle (as an example) has been measured at 5–10 s this is comparable with the lifetimes observed for ball lightning. The light output from a few hundred particles is estimated to be ~1 W, a typical output for ball lightning. Finally, suggestions are made for the generation of ball lightning in the laboratory.

  4. Planned hospital birth versus planned home birth

    DEFF Research Database (Denmark)

    Olsen, O.; Clausen, J.A.

    2012-01-01

    Observational studies of increasingly better quality and in different settings suggest that planned home birth in many places can be as safe as planned hospital birth and with less intervention and fewer complications. This is an update of a Cochrane review first published in 1998....

  5. DANGEROUS EXERCISES

    OpenAIRE

    Hassan Daneshmandi

    2011-01-01

    Research has shown that many exercises are contraindicated and may do more harm thanbenefits. Many of the warm-up exercises we practiced each day have now found to be dangerous.While different levels of athletics do have different levels of stretching; it is necessary to knowwhat the dangerous exercises are and how to use safer alternatives. Certain exercises are toorisky and should not be performed at all. Exercises must be performed in certain ways and ifperformed incorrectly can cause inju...

  6. Styrofoam-and-Velcro: An Alternative to Ball-and-Stick Models

    Directory of Open Access Journals (Sweden)

    Sawyer Rowan Masonjones

    2014-07-01

    Full Text Available For students learning biology at introductory levels, one of the most significant instructional barriers is their lack of preparation in chemistry. In upper-division college chemistry and biology courses, students employ ball-and-stick models in order to visualize molecular structures, but at the introductory biology level, models are inconsistently used and at the secondary level they are avoided altogether. Traditional ball-and-stick models perform poorly at all levels because they only show bonds, never valence electrons. This poses a problem for students who are visual or kinesthetic learners, as modeling electrons in the bonding process may be critical to understanding the mechanisms behind the biochemical reactions that serve as a foundation for biological concepts. Our molecular modeling kits show the action of valence electrons and correctly deal with the issue of polarity and partial charge, while still illustrating structure and function similarly to ball-and-stick models, allowing students to model nearly every reaction or molecule they may need to learn.  Additionally, this kit will foster model building exercises required as part of the Next Generation Science Standards (http://www.nextgenscience.org/next-generation-science-standards. This model was devloped in conjunction with 'Molecular Twister: A Game for Exploring Solution Chemistry' (JMBE Vol 15, No 1; http://jmbe.asm.org/index.php/jmbe/article/view/652 by the same authors, which uses principles derived from the present paper.

  7. Mental fatigue alters the speed and the accuracy of the ball in table tennis.

    Science.gov (United States)

    Le Mansec, Yann; Pageaux, Benjamin; Nordez, Antoine; Dorel, Sylvain; Jubeau, Marc

    2017-12-20

    This study aimed at evaluating the effects of mental and muscle fatigue on table tennis performance. Mental fatigue (MF) was induced by completion of 90 minutes of the AX-CPT; muscle fatigue was induced by completion of an eccentric exercise performed with the elbow flexors (biceps fatigue, BF) or the knee extensors (quadriceps fatigue, QF). The control condition consisted of watching a movie. Stroke parameters (speed and accuracy of the ball), as well as feelings of fatigue and force production capacity of the elbow flexors (BF, MF and control conditions) and knee extensors (QF condition), were assessed pre and post fatigue protocols. Feelings of fatigue increased post fatigue protocols. Force production capacity decreased only in the BF and QF conditions. BF and MF induced a decrease in accuracy. This decrease in accuracy was associated with an increased ball speed in the BF condition, and a decreased ball speed in the MF condition. QF had a negligible effect on stroke performance. Our results suggest that both mental fatigue, and muscle fatigue, significantly impair table tennis performance and therefore coaches should take into account both the physical and mental state of table tennis players to optimize performance.

  8. Effect of Practicing Soccer Juggling With Different Sized Balls Upon Performance, Retention, and Transfer to Ball Reception.

    Science.gov (United States)

    Raastad, Olav; Aune, Tore Kristian; van den Tillaar, Roland

    2016-10-01

    The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks. At the post and retention test both groups enhanced performance in soccer juggling test with no difference between groups and no increase in ball reception performance at these tests. It was concluded that about intra task transfer and retention of soccer juggling skills, it does not matter if you increase (small balls) or decrease the difficulty (larger balls) when using the same amount of practice time within the skill acquisition phase in soccer juggling. In addition that for ball juggling and ball reception (inter task) these two tasks differ too much in afferent information and movement characteristics that no positive transfer between these two skills no positive intertask transfer can be expected.

  9. Magnetohydrodynamics equilibrium of a self-confined elliptical plasma ball

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H. (CCAST (World Laboratory) P. O. Box 8730, Beijing 100080 and Institute of Mechanics, Academia Sinica, Beijing, People' s Republic of China (CN)); Oakes, M.E. (Department of Physics, University of Texas at Austin, Austin, Texas 78712 (USA))

    1991-08-01

    A variational principle is applied to the problem of magnetohydrodynamics (MHD) equilibrium of a self-contained elliptical plasma ball, such as elliptical ball lightning. The principle is appropriate for an approximate solution of partial differential equations with arbitrary boundary shape. The method reduces the partial differential equation to a series of ordinary differential equations and is especially valuable for treating boundaries with nonlinear deformations. The calculations conclude that the pressure distribution and the poloidal current are more uniform in an oblate self-confined plasma ball than that of an elongated plasma ball. The ellipticity of the plasma ball is obviously restricted by its internal pressure, magnetic field, and ambient pressure. Qualitative evidence is presented for the absence of sighting of elongated ball lightning.

  10. Burning molten metallic spheres: One class of ball lightning?

    Science.gov (United States)

    Stephan, Karl D.; Massey, Nathan

    2008-08-01

    Abrahamson and Dinniss [2000. Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil. Nature 403, 519-521] proposed a theory of ball lighting in which silicon nanoparticles undergo slow oxidation and emit light. Paiva et al. [2007. Production of ball-lightning-like luminous balls by electrical discharges in silicon. Physical Review Letters 98, 048501] reported that an electric arc to silicon produced long-lasting luminous white spheres showing many characteristics of ball lightning. We show experimentally that these consist of burning molten silicon spheres with diameters in the 0.1-1 mm range. The evidence of our experiments leads us to propose that a subset of ball lightning events may consist of macro-scale molten spheres of burning metallic materials likely to be ejected from a conventional lightning strike to earth.

  11. The heads and tails of buoyant autocatalytic balls

    Science.gov (United States)

    Rogers, Michael C.; Morris, Stephen W.

    2012-09-01

    Buoyancy produced by autocatalytic reaction fronts can produce fluid flows that advect the front position, giving rise to interesting feedback between chemical and hydrodynamic effects. In this paper, we numerically investigate the evolution of autocatalytic iodate-arsenous acid reaction fronts initialized in spherical configurations. Deformation of these "autocatalytic balls" is driven by buoyancy produced by the reaction. In our simulations, we have found that depending on the initial ball radius, the reaction front will develop in one of three different ways. In an intermediate range of ball size, the flow can evolve much like an autocatalytic plume: the ball develops a reacting head and tail that is akin to the head and conduit of an autocatalytic plume. In the limit of large autocatalytic balls, however, growth of a reacting tail is suppressed and the resemblance to plumes disappears. Conversely, very small balls of product solution fail to initiate sustained fronts and eventually disappear.

  12. Birth control pills - overview

    Science.gov (United States)

    ... from taking birth control pills include: Blood clots Heart attack High blood pressure Stroke Birth control pills without estrogen are much less likely to cause these problems. The risk is higher for women ...

  13. Preterm Labor and Birth

    Science.gov (United States)

    ... Facebook Twitter Pinterest Email Print Preterm Labor and Birth In general, a normal human pregnancy lasts about ... is called preterm labor (or premature labor). A birth that occurs before 37 weeks is considered a ...

  14. Birth control pill - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100108.htm Birth control pill - series—Normal female anatomy To use ... to produce a successful pregnancy. To prevent pregnancy, birth control pills affect how these organs normally function. ...

  15. Vaginal birth - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100198.htm Vaginal birth - series—Normal anatomy To use the sharing features ... vaginal delivery. Please keep in mind that every birth is unique, and your labor and delivery may ...

  16. Ball lightning observation: an objective video-camera analysis report

    OpenAIRE

    Sello, Stefano; Viviani, Paolo; Paganini, Enrico

    2011-01-01

    In this paper we describe a video-camera recording of a (probable) ball lightning event and both the related image and signal analyses for its photometric and dynamical characterization. The results strongly support the BL nature of the recorded luminous ball object and allow the researchers to have an objective and unique video document of a possible BL event for further analyses. Some general evaluations of the obtained results considering the proposed ball lightning models conclude the paper.

  17. Cranial birth trauma

    International Nuclear Information System (INIS)

    Papanagiotou, P.; Roth, C.; Politi, M.; Zimmer, A.; Reith, W.; Rohrer, T.

    2009-01-01

    Injuries to an infant that result during the birth process are categorized as birth trauma. Cranial injuries due to mechanical forces such as compression or traction include caput succedaneum, cephalhematoma, subgaleal hematoma and intracranial hemorrhaging. Hypoxic ischemic encephalopathy is the consequence of systemic asphyxia occurring during birth. (orig.) [de

  18. Encyclopedia of Birth Control.

    Science.gov (United States)

    Rengel, Marian

    This encyclopedia brings together in more than 200 entries, arranged in A-to-Z format, a portrait of the complex modern issue that birth control has become with advances in medicine and biochemistry during the 20th century. It is aimed at both the student and the consumer of birth control. Entries cover the following topics: birth control…

  19. Birth Control Shot

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Birth Control Shot KidsHealth / For Teens / Birth Control Shot What's in this article? What Is ... español La inyección anticonceptiva What Is It? The birth control shot is a long-acting form of ...

  20. Birth Control Pill

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Birth Control Pill KidsHealth / For Teens / Birth Control Pill What's in this article? What Is ... español La píldora anticonceptiva What Is It? The birth control pill (also called "the Pill") is a ...

  1. Birth Control Ring

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's in this article? What Is ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ...

  2. Spherical microwave confinement and ball lightning

    Science.gov (United States)

    Robinson, William Richard

    This dissertation presents the results of research done on unconventional energy technologies from 1995 to 2009. The present civilization depends on an infrastructure that was constructed and is maintained almost entirely using concentrated fuels and ores, both of which will run out. Diffuse renewable energy sources rely on this same infrastructure, and hence face the same limitations. I first examined sonoluminescence directed toward fusion, but demonstrated theoretically that this is impossible. I next studied Low Energy Nuclear Reactions and developed methods for improving results, although these have not been implemented. In 2000, I began Spherical Microwave Confinement (SMC), which confines and heats plasma with microwaves in a spherical chamber. The reactor was designed and built to provide the data needed to investigate the possibility of achieving fusion conditions with microwave confinement. A second objective was to attempt to create ball lightning (BL). The reactor featured 20 magnetrons, which were driven by a capacitor bank and operated in a 0.2 s pulse mode at 2.45 GHz. These provided 20 kW to an icosahedral array of 20 antennas. Video of plasmas led to a redesign of the antennas to provide better coupling of the microwaves to the plasma. A second improvement was a grid at the base of the antennas, which provided corona electrons and an electric field to aid quick formation of plasmas. Although fusion conditions were never achieved and ball lightning not observed, experience gained from operating this basic, affordable system has been incorporated in a more sophisticated reactor design intended for future research. This would use magnets that were originally planned. The cusp geometry of the magnetic fields is suitable for electron cyclotron resonance in the same type of closed surface that in existing reactors has generated high-temperature plasmas. Should ball lightning be created, it could be a practical power source with nearly ideal

  3. LOW COMPRESSION TENNIS BALLS AND SKILL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    John Hammond

    2006-12-01

    Full Text Available Coaching aims to improve player performance and coaches have a number of coaching methods and strategies they use to enhance this process. If new methods and ideas can be determined to improve player performance they will change coaching practices and processes. This study investigated the effects of using low compression balls (LCBs during coaching sessions with beginning tennis players. In order to assess the effectiveness of LCBs on skill learning the study employed a quasi-experimental design supported by qualitative and descriptive data. Beginner tennis players took part in coaching sessions, one group using the LCBs while the other group used standard tennis balls. Both groups were administered a skills at the beginning of a series of coaching sessions and again at the end. A statistical investigation of the difference between pre and post-test results was carried out to determine the effect of LCBs on skill learning. Additional qualitative data was obtained through interviews, video capture and the use of performance analysis of typical coaching sessions for each group. The skill test results indicated no difference in skill learning when comparing beginners using the LCBs to those using the standard balls. Coaches reported that the LCBs appeared to have a positive effect on technique development, including aspects of technique that are related to improving power of the shot. Additional benefits were that rallies went on longer and more opportunity for positive reinforcement. In order to provide a more conclusive answer to the effects of LCBs on skill learning and technique development recommendations for future research were established including a more controlled experimental environment and larger sample sizes across a longer period of time

  4. CFD Analysis of Swing of Cricket Ball and Trajectory Prediction

    Science.gov (United States)

    G, Jithin; Tom, Josin; Ruishikesh, Kamat; Jose, Jyothish; Kumar, Sanjay

    2013-11-01

    This work aims to understand the aerodynamics associated with the flight and swing of a cricket ball and predict its flight trajectory over the course of the game: at start (smooth ball) and as the game progresses (rough ball). Asymmetric airflow over the ball due to seam orientation and surface roughness can cause flight deviation (swing). The values of Drag, Lift and Side forces which are crucial for determining the trajectory of the ball were found with the help of FLUENT using the standard K- ɛ model. Analysis was done to study how the ball velocity, spin imparted to be ball and the tilt of the seam affects the movement of the ball through air. The governing force balance equations in 3 dimensions in combination a MATLAB code which used Heun's method was used for obtaining the trajectory of the ball. The conditions for the conventional swing and reverse swing to occur were deduced from the analysis and found to be in alignment with the real life situation. Critical seam angle for maximum swing and transition speed for normal to reverse swing were found out. The obtained trajectories were compared to real life hawk eye trajectories for validation. The analysis results were in good agreement with the real life situation.

  5. Promoting ball skills in preschool-age girls.

    Science.gov (United States)

    Veldman, Sanne L C; Palmer, Kara K; Okely, Anthony D; Robinson, Leah E

    2017-01-01

    Evidence supports that girls are less proficient than boys at performing ball skills. This study examined the immediate and long-term effects of a ball skill intervention on preschool-age girls' ball skill performance. Randomized controlled trial. Girls (M age =47.24±7.38 months) were randomly assigned to a high autonomy, mastery-based 9-week motor skill intervention (the Children's Health Activity Motor Program; CHAMP, 540min; n=38) or a control group (free-play; n=16). Ball skill proficiency was assessed at pretest, posttest, and retention test (after 9 weeks) using the object control subscale of the Test of Gross Motor Development - 2nd Edition. Treatment efficacy was examined using linear mixed models. Two models were fit: one for short-term changes (pretest to posttest) and one for long-term changes (pretest to retention). Linear mixed models revealed a significantly time*treatment interaction for both models. Post hoc analysis confirmed that girls in CHAMP experienced significant gains in ball skills from pretest to posttest (p.05) but had significantly higher ball skills scores at both posttest (pball skill intervention (i.e., CHAMP) on improving girls' ball skills both short- and long-term. Findings suggest that early childhood interventions that focus on the development of ball skills in young girls might be an avenue to improve girls' ball skill performance. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  6. Two Balls' Collision of Mass Ratio 3:1

    Science.gov (United States)

    Ogawara, Yasuo; Hull, Michael M.

    2018-04-01

    Students will sometimes ask why momentum and kinetic energy concepts are both necessary. When physics teachers demonstrate situations that require both an understanding of kinetic energy and momentum, a favorite is Newton's cradle, or a comparable demonstration of two balls of equal mass hitting each other. However, in addition to the case of two balls of equal mass, if a ball hits another ball of three times the mass with equal speed, the results are also interesting, and, like the equal-mass demonstration, both kinetic energy and momentum are critical for understanding the motion.

  7. A proposed experiment on ball lightning model

    Energy Technology Data Exchange (ETDEWEB)

    Ignatovich, Vladimir K., E-mail: v.ignatovi@gmail.com [Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Ignatovich, Filipp V. [1565 Jefferson Rd., 420, Rochester, NY 14623 (United States)

    2011-09-19

    Highlights: → We propose to put a glass sphere inside an excited gas. → Then to put a light ray inside the glass in a whispering gallery mode. → If the light is resonant to gas excitation, it will be amplified at every reflection. → In ms time the light in the glass will be amplified, and will melt the glass. → A liquid shell kept integer by electrostriction forces is the ball lightning model. -- Abstract: We propose an experiment for strong light amplification at multiple total reflections from active gaseous media.

  8. Are Perytons Signatures of Ball Lightning?

    Science.gov (United States)

    Dodin, I. Y.; Fisch, N. J.

    2014-10-01

    The enigmatic downchirped signals, called "perytons," that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  9. Collective flow measured with the Plastic Ball

    International Nuclear Information System (INIS)

    Ritter, H.G.; Gutbrod, H.H.; Kampert, K.H.; Kolb, B.; Poskanzer, A.M.; Schicker, R.; Schmidt, H.R.; Siemiarczuk, T.

    1989-08-01

    The experimental results from the Plastic Ball detector have contributed vastly to the understanding of the reaction mechanism of nuclear collisions at several hundred MeV per nucleon. The discovery of the collective flow phenomena (bounce-off of spectator fragments, side-splash in the reaction plane, and squeeze-out out of the reaction plane), as they were predicted by hydrodynamical models, has led to the experimental observation of compressed nuclear matter, which is a necessary condition before one can study the equation of state in detail and search for phase transitions at higher energies. 39 refs., 9 figs., 1 tab

  10. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  11. Results on charmonium from the Crystal Ball

    CERN Document Server

    Partridge, R; Bloom, Elliott D; Bulos, F; Burnett, T; Cavalli-Sforza, M; Chestnut, R; Coyne, D; Gaiser, J; Godfrey, G; Hofstadter, R; Kiesling, C; Kirkbride, I; Kolanoski, H; Kollmann, W; Liberman, A; O'Reilly, J; Oreglia, M J; Peck, C; Porter, F; Richardson, M; Sadrozinski, H F W; Strauch, K; Tompkins, J; Wacker, K

    1979-01-01

    Results from the Crystal Ball experiment at SPEAR are presented. A preliminary analysis of the 3 photon final state from the J/ psi (3095) and of the cascade decays of the psi '(3684) yield new upper limits on the controversial states X(2820), chi (3455) and the even C- parity state at 3.59 GeV. From inclusive gamma -ray spectra of the J/ psi and psi ' preliminary branching ratios for psi ' to chi states and upper limits for J/ psi , psi ' to eta /sub c/, eta /sub c/' are given. (15 refs).

  12. Ball Bearing Analysis with the ORBIS Tool

    Science.gov (United States)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  13. Crystal Ball evidence for new states

    International Nuclear Information System (INIS)

    Coyne, D.G.

    1981-09-01

    Evidence for three new particles observed in the Crystal Ball detector is presented. The first particle, at 3592 MeV, is seen inclusively in γ transitions from psi', and is thus a candidate for eta/sub c/'. The other two, at 1440 and 1640 MeV, are best seen in exclusive decays of psi involving a prompt γ, and are thus candidates for bound states of two gluons. Detailed reasons are presented to support the contention that these states are distinct from previously observed candidates such as E(1420). Alternative hypotheses are discussed

  14. Tar ball Monitoring Along the Kenyan Beaches.

    OpenAIRE

    Nguta, M.

    1993-01-01

    Observations and measurements of petroleum tar balls on a number of Kenyan beaches were carried out between 1979 and 1982. A large variation in the size and amount of tar deposit at the beaches was recorded. These values ranged from very small pebbles to large lumps of 30 cm in diameter, weighing up to 1.5 kg. The average tar loading during the sampling period ranged from 0-18 g/m2. Between 25-50% by weight of the tar lumps were shell fragments, sand and other nonpetroleum debris. The chemica...

  15. RELATIONSHIP BETWEEN MEDICINE BALL EXPLOSIVE POWER TESTS, THROWING BALL VELOCITY AND JUMP PERFORMANCE IN TEAM HANDBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Mourad Fathloun

    2011-04-01

    Full Text Available In this study, the relationships between medicine ball explosive power tests, jump and handball throwing velocity performance in team handball players were investigated. Explosive test was measured by a medicine ball throw. Specific explosive strength was evaluated by making 3 types of overarm throw: standing position, using an adapted chair (without run-up, T w , a 3-step running throw (T 3-Steps and a jump shot (J S . The jump test (SJ, CMJ and FCMJ were determined using the OptoJump. The medicine ball explosive power test was closely related to T 3-Steps . Significant relationships were observed between medicine ball explosive power tests and (J S and (T w . The Medicine ball explosive power test is also positively related to vertical jump ability represented by Squat Jump (SJ and Countermovement Jump (CMJ. The results suggest an association of the medicine ball explosive power tests to performance in throwing events

  16. The information for catching fly balls : Judging and intercepting virtual balls in a CAVE

    NARCIS (Netherlands)

    Zaal, FTJM; Michaels, CF

    Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy-keeping constant the rate of change of the tangent of the elevation angle (d(tan(alpha))/dt)-leads a catcher to the right location at

  17. The information for catching fly balls: judging and intercepting virtual balls in a CAVE

    NARCIS (Netherlands)

    Zaal, F.T.J.M.; Michaels, C.F.

    2003-01-01

    Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy - keeping constant the rate of change of the tangent of the elevation angle (d(tan(α))/dt) - leads a catcher to the right location at

  18. Respiratory disease in ball pythons (Python regius) experimentally infected with ball python nidovirus.

    Science.gov (United States)

    Hoon-Hanks, Laura L; Layton, Marylee L; Ossiboff, Robert J; Parker, John S L; Dubovi, Edward J; Stenglein, Mark D

    2018-04-01

    Circumstantial evidence has linked a new group of nidoviruses with respiratory disease in pythons, lizards, and cattle. We conducted experimental infections in ball pythons (Python regius) to test the hypothesis that ball python nidovirus (BPNV) infection results in respiratory disease. Three ball pythons were inoculated orally and intratracheally with cell culture isolated BPNV and two were sham inoculated. Antemortem choanal, oroesophageal, and cloacal swabs and postmortem tissues of infected snakes were positive for viral RNA, protein, and infectious virus by qRT-PCR, immunohistochemistry, western blot and virus isolation. Clinical signs included oral mucosal reddening, abundant mucus secretions, open-mouthed breathing, and anorexia. Histologic lesions included chronic-active mucinous rhinitis, stomatitis, tracheitis, esophagitis and proliferative interstitial pneumonia. Control snakes remained negative and free of clinical signs throughout the experiment. Our findings establish a causal relationship between nidovirus infection and respiratory disease in ball pythons and shed light on disease progression and transmission. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Saving lives at birth

    DEFF Research Database (Denmark)

    Daysal, N. Meltem; Trandafir, Mircea; van Ewijk, Reyn

    2015-01-01

    Many developed countries have recently experienced sharp increases in home birth rates. This paper investigates the impact of home births on the health of low-risk newborns using data from the Netherlands, the only developed country where home births are widespread. To account for endogeneity...... in location of birth, we exploit the exogenous variation in distance from a mother’s residence to the closest hospital. We find that giving birth in a hospital leads to substantial reductions in newborn mortality. We provide suggestive evidence that proximity to medical technologies may be an important...

  20. Early discharge following birth

    DEFF Research Database (Denmark)

    Nilsson, Ingrid M. S.; Kronborg, Hanne; Knight, Christopher H.

    2017-01-01

    of discharge after birth. Results In total 34% mothers were discharged within 12 hours (very early) and 25% between 13 and 50 hours (early), respectively. Vaginal birth and multiparity were the most influential predictors, as Caesarean section compared to vaginal birth had an OR of 0.35 (CI 0....... Smoking, favourable social support and breastfeeding knowledge were significantly associated with discharge within 12 hours. Finally time of discharge varied significantly according to region and time of day of birth. Conclusions Parity and birth related factors were the strongest predictors of early...

  1. Understanding Pregnancy and Birth Issues

    Science.gov (United States)

    ... Home Current Issue Past Issues Understanding Pregnancy and Birth Issues Past Issues / Winter 2008 Table of Contents ... about NICHD preeclampsia research in the sidebar.) Preterm Birth Preterm (premature) birth is birth before the baby ...

  2. Planned place of birth

    DEFF Research Database (Denmark)

    Overgaard, Charlotte; Coxon, Kirstie; Stewart, Mary

    in Denmark Coxon K et al: Planned place of birth in England: perceptions of accessing obstetric units, midwife led units and home birth amongst women and their partners. How these papers interrelate These papers draw upon recent research in maternity care, undertaken in Denmark and in England. In both......Title Planned place of birth: issues of choice, access and equity. Outline In Northern European countries, giving birth is generally safe for healthy women with uncomplicated pregnancies, and their babies. However, place of birth can affect women’s outcomes and experiences of birth. Whilst tertiary...... centres provide appropriate medical supervision to women with complex pregnancies, the likelihood of receiving interventions including surgical birth is increased for low risk women in these settings. In this symposium, we consider issues of choice, access and equitable care for women in the context...

  3. Two Cases of Hair Balls in Girls

    Directory of Open Access Journals (Sweden)

    Vladimir A. Shcherbak

    2016-01-01

    Full Text Available This article describes two cases of hair balls in girls between aged 2.5 and 12 years. The reason for this quite rare disease may be trichotillomania (compulsive desire to pull out own hair and trichophagia (compulsive or impulsive desire to pull out, and then to swallow own or someone's hair typical for Rapunzel syndrome. Initially, the children were enrolled in the Oncology Centre in view of suspected abdominal tumour. After detection of foreign bodies in the stomach, they were transferred to the Department of Clean Surgery. The following surgeries were performed: median laparotomy, gastrotomy on the front wall of the stomach, bezoar removal. Hair balls were dense felt-like conglomerates with a strong offensive odour. Bezoar dimensions of the younger girl were 855, the elder one — 20108 cm. Postoperative period was uneventful. The children were discharged in a satisfactory condition to be followed up by a surgeon, paediatrician, and psychiatrist in their community.

  4. James Moores Ball: Ophthalmologist, medical historian, bibliophile.

    Science.gov (United States)

    Feibel, Robert M

    2016-08-01

    James Moores Ball (1862-1929) was an ophthalmologist in St. Louis, Missouri, who excelled as a medical historian and collector of rare and historic books about the history of anatomy. During his lifetime, he was best known as the author of a comprehensive, authoritative, and popular textbook titled Modern Ophthalmology First published in 1904, there were five further editions. Ball was very interested in the history of anatomy and wrote two books on this subject, the first being a biography of Andreas Vesalius, one of the earliest in English, and the second a history of the resurrection men or grave robbers who sold corpses to professors of anatomy and surgery for teaching purposes. His legacy today is the 470 volumes of his personal library, which are now in the Archives and Rare Books department of the Becker Medical Library of the Washington University School of Medicine. These texts are one of their major collections, concentrating on the history of anatomy, beginning with a first edition of Vesalius's De Humani Corporis Fabrica and holding many important and beautiful landmark volumes of anatomical atlases. © The Author(s) 2016.

  5. Prevention: Exercise

    Medline Plus

    Full Text Available ... martial arts all provide well-rounded core strengthening programs. Simple exercises can be done at home as ... doctor or physical therapist to prescribe an exercise program that matches your abilities. Neck Press This is ...

  6. Exercise Headaches

    Science.gov (United States)

    ... headaches may require emergency medical attention. Symptoms Primary exercise headaches These headaches: Are usually described as throbbing ... sides of the head in most cases Secondary exercise headaches These headaches may cause: The same symptoms ...

  7. Prevention: Exercise

    Medline Plus

    Full Text Available ... strengthening programs. Simple exercises can be done at home as well. Some specific core strengthening exercises are ... a Success Story to Share? | Contact Us SPINE CARE PROVIDERS GO HERE © 2018 North American Spine Society | ...

  8. Prevention: Exercise

    Medline Plus

    Full Text Available ... movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. ... repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing ...

  9. Prevention: Exercise

    Medline Plus

    Full Text Available ... prescribe an exercise program that matches your abilities. Neck Press This is an isometric exercise to strengthen your neck. Press your palm against your forehead, then use ...

  10. Exercise Habit

    Science.gov (United States)

    ... or months before you notice some of the benefits of exercise, such as weight loss. If you miss a ... can also keep you accountable. Think of the benefits of regular exercise. Write down the benefits and goals, and keep ...

  11. Prevention: Exercise

    Medline Plus

    Full Text Available ... body. Pilates, yoga and martial arts all provide well-rounded core strengthening programs. Simple exercises can be done at home as well. Some specific core strengthening exercises are described below. ...

  12. Prevention: Exercise

    Medline Plus

    Full Text Available ... Aerobic Exercise Cervical Exercise Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain ... area. This can be done with quick short movements, or slow full movements. Repeat 10-15 times, ...

  13. Activity profile of top-class female soccer refereeing in relation to the position of the ball.

    Science.gov (United States)

    Mallo, J; Veiga, S; López de Subijana, C; Navarro, E

    2010-01-01

    The aim of this study was to describe the activity profile of top-class female soccer referees during competition and to relate it to the position of the ball. Ten matches from the Fédération Internationale de Football Association (FIFA) under-20 female World Championships held in Russia in 2006 were filmed and the kinematical parameters of the female referees (n=10) and the ball were determined using a two-dimensional photogrammetric video system based on direct linear transformation (DLT) algorithms. Total distance covered during a match was 10 km, of which 1.3 km represented high-intensity activities (>13 km/h). The referees' highest mobility was achieved in the initial 15 min of the match, covering greater distance and performing more intense exercise (Preferee to the ball was 19.5+/-2.4m, with no significant differences between 15 min match periods. The results of this study show that: (1) the physical demands placed on top-class female referees are much like those experienced during male moderate-standard refereeing and (2) the referees were able to maintain the distance from the ball throughout the match. Copyright (c) 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  14. Modeling and Analyzing the Slipping of the Ball Screw

    Directory of Open Access Journals (Sweden)

    Nannan Xu

    Full Text Available AbstractThis paper aims to set up the ball systematic slipping model and analyze the slipping characteristics caused by different factors for a ball screw operating at high speeds. To investigate the ball screw slipping mechanism, transformed coordinate system should be established firstly. Then it is used to set up mathematical modeling for the ball slipping caused by the three main reasons and the speed of slipping can be calculated. Later, the influence of the contact angle, helix angle and screw diameter for ball screw slipping will be analyzed according to the ball slipping model and slipping speeds equation and the slipping analysis will be obtained. Finally, curve of slipping analysis and that of mechanical efficiency of the ball screw analysis by Lin are compared, which will indirectly verify the correctness of the slipping model. The slipping model and the curve of slipping analysis established in this paper will provide theory basis for reducing slipping and improving the mechanical efficiency of a ball screw operating at high speeds.

  15. How Magnus Bends the Flying Ball - Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-02-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways, resulting in a so-called banana kick that can confuse the goalkeeper. These surprising effects attract students' attention such that the motion of sports balls can be used to capture the interest of students towards the physics behind it. However, to study and analyze the motion of a real ball kicked in a playfield is not an easy task. Instead of the large-scale full-size sports ball motion, there can be designed and studied simpler experiments that can be carried out in the classroom. Moreover, digital technologies that are available at schools enable students to collect data from the experiment easily in a reasonable time. The mathematical model based on the analysis of forces acting on the ball flying in the air can be used to simulate the motion in order to understand the basic physical principles of the motion so that the best correspondence may be found.

  16. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in

  17. Physical Activity Benefits Creativity: Squeezing a Ball for Enhancing Creativity

    Science.gov (United States)

    Kim, JongHan

    2015-01-01

    Studies in embodied cognition show that physical sensations, such as touch and movement, influence cognitive processes. Two studies were conducted to test whether squeezing a soft versus a hard ball facilitates different types of creativity. Squeezing a malleable ball would increase divergent creativity by catalyzing multiple or alternative ideas,…

  18. Motion of a Ball on a Moving Surface

    Science.gov (United States)

    Cross, Rod

    2016-01-01

    A well-known physics demonstration is to pull a tablecloth rapidly from under some crockery without disturbing the crockery. An interesting question is whether the same result can be expected if the crockery is replaced by a ball, given that the ball might roll backwards on the tablecloth. Theoretical and experimental results are presented showing…

  19. Production of nano structured silicon carbide by high energy ball ...

    African Journals Online (AJOL)

    In this paper, an attempt has been made to modify the micro sized Silicon carbide powder into nano structured Silicon carbide powder using High Energy Ball Mill. Ball milling was carried out for the total duration of 50 hours. The sample was taken out after every 5 hours of milling and it was characterized for its crystallite ...

  20. Why Low Bounce Balls Exhibit High Rolling Resistance

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A simple experiment is described to measure the coefficient of rolling friction for a low bounce ball rolling on a horizontal surface. As observed previously by others, the coefficient increased with rolling speed. The energy loss due to rolling friction can be explained in terms of the measured coefficient of restitution for the ball, meaning…

  1. Between Traditions: Stephen Ball and the Critical Sociology of Education

    Science.gov (United States)

    Apple, Michael W.

    2013-01-01

    Stephen Ball's work has deservedly received a good deal of attention. In this article, I detail a number of tasks in which the critical sociologist of education--as a "public intellectual"--should engage. I then place Ball's work within these tasks and evaluate his contributions to them. In the process, I show that one of the…

  2. Launch Creativity with Ping-Pong Ball Challenge

    Science.gov (United States)

    Kornoelje, Joanne; Roman, Harry T.

    2011-01-01

    Educators at Thomas A. Edison Middle School have worked together to bring invention information and activities to life. One activity in particular, Ping-Pong Ball Invention Challenge, has proven a great success. The Ping-Pong Ball Invention Challenge was inspired by the basic rules for PBS's "Design Squad"'s "Pop Fly" activity. In this article,…

  3. Exact solutions, energy, and charge of stable Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Marques, M.A. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2016-05-15

    In this work we deal with nontopological solutions of the Q-ball type in two spacetime dimensions. We study models of current interest, described by a Higgs-like and other, similar potentials which unveil the presence of exact solutions. We use the analytic results to investigate how to control the energy and charge to make the Q-balls stable. (orig.)

  4. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  5. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  6. Two balls and a string: from ordered motion to chaos

    Science.gov (United States)

    Sacks, William; Mauger, Alain

    2013-11-01

    Two spherical balls are connected by a taught string passing through a small hole in a perfectly planar table: the first ball, subject to a central force, moves without friction on a two-dimensional plane, while the second ball moves only along the vertical axis directly below the hole. The pedagogical aspects of this novel two-body problem are given particular attention: Newton’s laws, central force motion, conservation laws, angular momentum, constraints, etc. The dynamics of the system is considered under various initial conditions wherein the ball on the table moves qualitatively in rotating ellipses or hypotrochoids. The conditions for closed or periodic orbits are examined. The more complex case of the inclined plane is then considered, revealing a rich variety of periodic, aperiodic and chaotic solutions as a function of the ball mass ratio and the plane inclination angle. The associated Poincaré phase-space maps are discussed.

  7. Friction torque in thrust ball bearings grease lubricated

    Science.gov (United States)

    Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

    2016-08-01

    The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

  8. Une balle blanche dans un roman noir

    Directory of Open Access Journals (Sweden)

    Sophie Vallas

    2012-03-01

    Full Text Available En 1982, Paul Auster fit paraître, sous le pseudonyme de Paul Benjamin, un roman noir intitulé Squeeze Play. Ce roman présente la particularité d’appartenir également au genre du baseball novel, l’intrigue se déroulant en partie dans le monde du base-ball et sa résolution intervenant grâce à une manœuvre rare et spectaculaire (un double suicide squeeze qui éclaire l’enquête sous un jour nouveau. Cet article se propose d’analyser la place du base-ball dans Squeeze Play : élément essentiel de la structuration du roman, le base-ball permet également à Auster d’étudier le mythe du héros américain déchu dans une société dont toutes les dimensions (sportive, politique, privée sont gangrenées par la corruption et la perversion. La relation particulière qu’Auster tisse entre roman noir et baseball novel est également étudiée.In 1982 Paul Auster published a roman noir entitled Squeeze Play under the pseudonym of Paul Benjamin. The novel is also a “baseball novel”: its plot essentially deals with a baseball New York team and its former, fallen star, and the final resolution of the mystery intervenes thanks to a revelation brought by a baseball game in which a rather rare and spectacular maneuver (the double suicide squeeze is used by one of the teams to turn the tables and win the game. This paper analyzes the place of baseball in Squeeze Play: it first appears as an essential element in the very structure of the plot, but it is also, for Auster, a way of questioning the myth of the hero in an American society whose main aspects (sports, politics, private life are eaten up by corruption and perversion. The links Auster establishes between roman noir and baseball novel are also dealt with.

  9. Exercise addiction

    DEFF Research Database (Denmark)

    Lichtenstein, Mia Beck; Christiansen, Erik; Elklit, Ask

    2014-01-01

    Exercise addiction is characterized by excessive exercise patterns with potential negative consequences such as overuse injuries. The aim of this study was to compare eating disorder symptoms, quality of life, personality traits and attachments styles in exercisers with and without indications...... of exercise addiction. A case-control study with 121 exercisers was conducted. The exercisers were categorized into an addiction group (n=41) or a control group (n=80) on the basis of their responses to the Exercise Addiction Inventory. The participants completed the Eating Disorder Inventory 2, the Short......-Form 36, the NEO Personality Inventory Revised and the Adult Attachment Scale. The addiction group scored higher on eating disorder symptoms, especially on perfectionism but not as high as eating disorder populations. The characteristic personality traits in the addiction group were high levels...

  10. The relationships between impact location and post-impact ball speed, bat torsion, and ball direction in cricket batting.

    Science.gov (United States)

    Peploe, C; McErlain-Naylor, S A; Harland, A R; King, M A

    2018-06-01

    Three-dimensional kinematic data of bat and ball were recorded for 239 individual shots performed by twenty batsmen ranging from club to international standard. The impact location of the ball on the bat face was determined and assessed against the resultant instantaneous post-impact ball speed and measures of post-impact bat torsion and ball direction. Significant negative linear relationships were found between post-impact ball speed and the absolute distance of impact from the midline medio-laterally and sweetspot longitudinally. Significant cubic relationships were found between the distance of impact from the midline of the bat medio-laterally and both a measure of bat torsion and the post-impact ball direction. A "sweet region" on the bat face was identified whereby impacts within 2 cm of the sweetspot in the medio-lateral direction, and 4.5 cm in the longitudinal direction, caused reductions in ball speed of less than 6% from the optimal value, and deviations in ball direction of less than 10° from the intended target. This study provides a greater understanding of the margin for error afforded to batsmen, allowing researchers to assess shot success in more detail, and highlights the importance of players generating consistently central impact locations when hitting for optimal performance.

  11. ANALYSES OF VOLLEY-BALL TECHNIQUE OF BALL SHOTING AT ALOFT BOUNCE BY USING KINEMATICS METHOD

    Directory of Open Access Journals (Sweden)

    Radoslav Bubanj

    2008-08-01

    Full Text Available In the sports hall, student of Faculty of sports and physical education demonstrated technique of ball shoting at aloft bounce in volley-ball. That element of technique was recorded by using of digital camera. Video record was mistreated and prepared for further manipulating which considered admeasurement of reference points on 13-th model system withdrawal of appropriate ”Human“ software. After that, basics kinematics variables were calculated. All results were graphically presented and interpreted. Descriptive method was used as supplementary method which gave informations about impacts of single handed velocities of body segments on length of horizontally and vertically path which outpassed body gravity centre. Descriptive method also gave results about regularity of performed complex element of technique.

  12. Poincare ball embeddings of the optical geometry

    International Nuclear Information System (INIS)

    Abramowicz, M A; Bengtsson, I; Karas, V; Rosquist, K

    2002-01-01

    It is shown that the optical geometry of the Reissner-Nordstroem exterior metric can be embedded in a hyperbolic space all the way down to its outer horizon. The adopted embedding procedure removes a breakdown of flat-space embeddings which occurs outside the horizon, at and below the Buchdahl-Bondi limit (R/M=9/4 in the Schwarzschild case). In particular, the horizon can be captured in the optical geometry embedding diagram. Moreover, by using the compact Poincare ball representation of the hyperbolic space, the embedding diagram can cover the whole extent of radius from spatial infinity down to the horizon. Attention is drawn to the advantages of such embeddings in an appropriately curved space: this approach gives compact embeddings and it clearly distinguishes the case of an extremal black hole from a non-extremal one in terms of the topology of the embedded horizon

  13. Are perytons signatures of ball lightning?

    Energy Technology Data Exchange (ETDEWEB)

    Dodin, I. Y.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08543 (United States)

    2014-10-20

    The enigmatic downchirped signals, called 'perytons', that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  14. Unpredictable Property of a Kicked Billiard Ball

    International Nuclear Information System (INIS)

    Shen Ying; Dai Jun; Jiang Yumei; He Yue; He Daren

    2006-01-01

    A simultaneous change in the systemic property of a kicked billiard ball is observed from an entirely smooth and conservative state to a piecewise smooth and quasi-dissipative state when a single controlling parameter has been adjusted. The transition induces a sudden change of a typical conservative stochastic web into a transient web. The iterations on the transient web eventually escape to some elliptic islands. In the meantime, a fat fractal forbidden web, which appears also at the threshold, grows up and cuts away increasingly more parts from the original conservative stochastic web. We numerically show that the initial conditions that generated different attractors are mixed in a random manner and the pattern remains unchanged even when smaller and smaller scales are used for examination, indicating a riddle-like basin structure that practically rules out the possibility of predicting the attractors from a given initial condition

  15. Epidemiology of preterm birth.

    Science.gov (United States)

    Purisch, Stephanie E; Gyamfi-Bannerman, Cynthia

    2017-11-01

    Preterm birth is a worldwide epidemic with a global incidence of 15 million per year. Though rates of preterm birth in the United States have declined over the last decade, nearly 1 in 10 babies is still born preterm. The incidence, gestational age, and underlying etiology of preterm birth is highly variable across different racial and ethnic groups and geographic boundaries. In this article, we review the epidemiology of preterm birth in the United States and globally, with a focus on temporal trends and racial, ethnic, and geographic disparities. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Health and Physiological Adaptations of Small-Sided Ball Games in Untrained Older Adults Aged 65-93 Years

    DEFF Research Database (Denmark)

    Vorup Petersen, Jacob

    Introduction. Aging is associated with a physiological decline that contributes to loss of physical function and increased risk of adverse cardiovascular events and development of type 2 diabetes. The vast majority of research has focused on traditional exercise activities such as brisk walking...... was consistently shown to improve physical function in untrained elderly (I, II, III). Also reduced heart rate at rest and during submaximal exercise as well as a drop in body fat was evident (I, II). Muscle mass was unaffected by floorball training and small-sided ball game training followed by low protein intake......, cycling or resistance training in the prevention of this physiological decline with age. However, untrained elderly may be reluctant to participate in multiple training sessions a week, and may also be unwilling to take part in intense exercise due to motivational reasons. Thus, efficient and motivating...

  17. Health and Physiological Adaptations of Small-Sided Ball Games in Untrained Older Adults Aged 65-93 Years

    DEFF Research Database (Denmark)

    Vorup Petersen, Jacob

    Introduction. Aging is associated with a physiological decline that contributes to loss of physical function and increased risk of adverse cardiovascular events and development of type 2 diabetes. The vast majority of research has focused on traditional exercise activities such as brisk walking......, cycling or resistance training in the prevention of this physiological decline with age. However, untrained elderly may be reluctant to participate in multiple training sessions a week, and may also be unwilling to take part in intense exercise due to motivational reasons. Thus, efficient and motivating...... was consistently shown to improve physical function in untrained elderly (I, II, III). Also reduced heart rate at rest and during submaximal exercise as well as a drop in body fat was evident (I, II). Muscle mass was unaffected by floorball training and small-sided ball game training followed by low protein intake...

  18. Physical exercise during pregnancy: a systematic review.

    Science.gov (United States)

    Nascimento, Simony L; Surita, Fernanda G; Cecatti, José G

    2012-12-01

    This review aims to provide an update on the recent evidence concerning exercise during pregnancy including effects for mother and fetus and the types, frequency, intensity, duration and rate of progression of exercise performed. Exercises during pregnancy are associated with higher cardiorespiratory fitness, prevention of urinary incontinence and low back pain, reduced symptoms of depression, gestational weight gain control, and for cases of gestational diabetes, reduced number of women who required insulin. There is no association with reduction in birth weight or preterm birth rate. The type of exercise shows no difference on results, and its intensity should be mild or moderate for previous sedentary women and moderate to high for active women. The exercise recommendations still are based on the current guidelines on moderate-intensity, low-impact, aerobic exercise at least three times a week. Yet, new guidelines propose increasing weekly physical-activity expenditure while incorporating vigorous exercise and adding light strength training to the exercise routine of healthy pregnant women. In the case of other chronic diseases like hypertension, there are still few data, and therefore more studies should be performed to assess the safety of the intervention. Physical exercise is beneficial for women during pregnancy and also in the postpartum period; it is not associated with risks for the newborn and can lead to changes in lifestyle that imply long-term benefits.

  19. Investigation of a Plasma Ball using a High Speed Camera

    Science.gov (United States)

    Laird, James; Zweben, Stewart; Raitses, Yevgeny; Zwicker, Andrew; Kaganovich, Igor

    2008-11-01

    The physics of how a plasma ball works is not clearly understood. A plasma ball is a commercial ``toy'' in which a center electrode is charged to a high voltage and lightning-like discharges fill the ball with many plasma filaments. The ball uses high voltage applied on the center electrode (˜5 kV) which is covered with glass and capacitively coupled to the plasma filaments. This voltage oscillates at a frequency of ˜26 kHz. A Nebula plasma ball from Edmund Scientific was filmed with a Phantom v7.3 camera, which can operate at speeds up to 150,000 frames per second (fps) with a limit of >=2 μsec exposure per frame. At 100,000 fps the filaments were only visible for ˜5 μsec every ˜40 μsec. When the plasma ball is first switched on, the filaments formed only after ˜800 μsec and initially had a much larger diameter with more chaotic behavior than when the ball reached its final plasma filament state at ˜30 msec. Measurements are also being made of the final filament diameter, the speed of the filament propagation, and the effect of thermal gradients on the filament density. An attempt will be made to explain these results from plasma theory and movies of these filaments will be shown. Possible theoretical models include streamer-like formation, thermal condensation instability, and dielectric barrier discharge instability.

  20. Tracking of Ball and Players in Beach Volleyball Videos

    Science.gov (United States)

    Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

    2014-01-01

    This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

  1. Do we hear size or sound? Balls dropped on plates.

    Science.gov (United States)

    Grassi, Massimo

    2005-02-01

    The aim of this study is to examine whether it is possible to recover directly the size of an object from the sound of an impact. Specifically, the study is designed to investigate whether listeners can tell the size of a ball from the sound when it is dropped on plates of different diameters (on one, two, or three plates in Experiments 1, 2, and 3, respectively). In this paradigm, most of the sound produced is from the plate rather than the ball. Listeners were told neither how many different balls or plates were used nor the materials of the balls and plates. Although listeners provided reasonable ball size estimates, their judgments were influenced by the size of the plate: Balls were judged to be larger when dropped on larger plates. Moreover, listeners were generally unable to recognize either ball and plate materials or the number of plates used in Experiments 2 and 3. Finally, various acoustic properties of the sounds are shown to be correlated with listeners' judgments.

  2. THEORETICAL ANALYSIS OF THE FORGING PROCESS FOR PRODUCING HOLLOW BALLS

    Directory of Open Access Journals (Sweden)

    Grzegorz Winiarski

    2013-06-01

    Full Text Available Hollow balls are used in the production of various machines and devices. The technology for producing hollow balls by metal forming technologies poses numerous difficulties connected with the forming of a hollow billet. The billet, which is usually in a form of a rod, is a subject to such processes as forging, helical rolling or cross-wedge rolling. The paper discusses a new method and conditions for producing a hollow ball. It was assumed that the ball would be produced in two forging operations: an initial forging operation and finishing forging operation. The presented results are based on the FEM numerical analysis conducted using DEFORM-3D. It was assumed that the billet material was made of AISI 304 stainless steel used to produce balls for ball valves. Both the shape progression during the forging process and variations in the forming force were analyzed. Based on the conducted analyses, it can be claimed that hollow balls can be produced using the proposed forging method.

  3. Tracking of ball and players in beach volleyball videos.

    Directory of Open Access Journals (Sweden)

    Gabriel Gomez

    Full Text Available This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points.

  4. Tracking of ball and players in beach volleyball videos.

    Science.gov (United States)

    Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

    2014-01-01

    This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points.

  5. Simulation of General Physics laboratory exercise

    International Nuclear Information System (INIS)

    Aceituno, P; Hernández-Cabrera, A; Hernández-Aceituno, J

    2015-01-01

    Laboratory exercises are an important part of general Physics teaching, both during the last years of high school and the first year of college education. Due to the need to acquire enough laboratory equipment for all the students, and the widespread access to computers rooms in teaching, we propose the development of computer simulated laboratory exercises. A representative exercise in general Physics is the calculation of the gravity acceleration value, through the free fall motion of a metal ball. Using a model of the real exercise, we have developed an interactive system which allows students to alter the starting height of the ball to obtain different fall times. The simulation was programmed in ActionScript 3, so that it can be freely executed in any operative system; to ensure the accuracy of the calculations, all the input parameters of the simulations were modelled using digital measurement units, and to allow a statistical management of the resulting data, measurement errors are simulated through limited randomization

  6. Water Bouncing Balls: how material stiffness affects water entry

    Science.gov (United States)

    Truscott, Tadd

    2014-03-01

    It is well known that one can skip a stone across the water surface, but less well known that a ball can also be skipped on water. Even though 17th century ship gunners were aware that cannonballs could be skipped on the water surface, they did not know that using elastic spheres rather than rigid ones could greatly improve skipping performance (yet would have made for more peaceful volleys). The water bouncing ball (Waboba®) is an elastic ball used in a game of aquatic keep away in which players pass the ball by skipping it along the water surface. The ball skips easily along the surface creating a sense that breaking the world record for number of skips could easily be achieved (51 rock skips Russell Byers 2007). We investigate the physics of skipping elastic balls to elucidate the mechanisms by which they bounce off of the water. High-speed video reveals that, upon impact with the water, the balls create a cavity and deform significantly due to the extreme elasticity; the flattened spheres resemble skipping stones. With an increased wetted surface area, a large hydrodynamic lift force is generated causing the ball to launch back into the air. Unlike stone skipping, the elasticity of the ball plays an important roll in determining the success of the skip. Through experimentation, we demonstrate that the deformation timescale during impact must be longer than the collision time in order to achieve a successful skip. Further, several material deformation modes can be excited upon free surface impact. The effect of impact velocity and angle on the two governing timescales and material wave modes are also experimentally investigated. Scaling for the deformation and collision times are derived and used to establish criteria for skipping in terms of relevant physical parameters.

  7. Resettlement and Birth Rates

    African Journals Online (AJOL)

    GB

    effect on mothers' age at first birth (p < 0.001), the number of children born within the five years of the survey (p<0.001), and the total number of ... approach that compares reported numbers of births for settlers and non-settlers in ... 1Department of Geography, Sonoma State University, USA. 2. Department of Epidemiology ...

  8. Birth Control Methods

    Science.gov (United States)

    ... Women can choose from many different types of birth control methods. These include, in order of most effective to least effective at preventing pregnancy: Female and male sterilization (female tubal ligation or occlusion, male vasectomy) — Birth control that prevents pregnancy for the rest of ...

  9. Extremely Preterm Birth

    Science.gov (United States)

    ... Search FAQs Extremely Preterm Birth Page Navigation ▼ ACOG Pregnancy Book Patient Education FAQs Patient Education Pamphlets - Spanish FAQ173, June 2016 ... Labor and Birth (FAQ087) Tobacco, Alcohol, Drugs, and Pregnancy (FAQ170) Patient Education ... Committee Opinions Practice Bulletins Patient ...

  10. Elizabeth Belle's Birth Story.

    Science.gov (United States)

    Boro, Jessica; Boro, Samuel

    2014-01-01

    In this article, Jessica and Samuel Boro share the story of the birth of their daughter, Elizabeth Belle. With the physical and emotional support of her husband and her doula, this mother was able to cope with a long labor and have the natural birth she wanted. Her husband describes how important the doula was for him.

  11. birth-weight infants

    African Journals Online (AJOL)

    hours of life was more strongly associated with death than four traditional risk factors (birth weight, short gestation, male sex and the diagnosis of respiratory distress syndrome). Furthermore, mean pH in the first 12 hours was as strongly associated with death as was birth weight. Previous research in our neonatal population ...

  12. Prevention: Exercise

    Medline Plus

    Full Text Available ... Steroid Injections Lumbar Zygapophysical (Facet) Joint Injections PREVENTION Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen ...

  13. Prevention: Exercise

    Medline Plus

    Full Text Available ... Exercises Electrothermal Modalities Ergonomic Changes Hydrotherapy Manual Therapy Physical Therapy Postural Training Traction Watchful Waiting and Education Injection Treatments for Spinal Pain Epidural Steroid Injections ...

  14. Narcissism and birth order.

    Science.gov (United States)

    Eyring, W E; Sobelman, S

    1996-04-01

    The purpose of this investigation was to clarify the relationship between birth-order position and the development of narcissism, while refining research and theory. The relationship between birth-order status and narcissism was examined with a sample of 79 undergraduate students (55 women and 24 men). These subjects were placed in one of the four following birth-order categories of firstborn, second-born, last-born, and only children. These categories were chosen given their significance in Adlerian theory. Each subject completed the Narcissistic Personality Inventory and a demographic inventory. Based on psychodynamic theory, it was hypothesized that firstborn children were expected to score highest, but statistical significance was not found for an association between narcissism and birth order. Further research is urged to investigate personality theory as it relates to parenting style and birth order.

  15. Ball lightning from a water beaker; Kugelblitze aus dem Wasserbecher

    Energy Technology Data Exchange (ETDEWEB)

    Buehrke, T.

    2008-07-01

    The very existence of these balls of light is the subject of controversy. People who have seen them say they can move along power lines and even go through window panes. Until recently, there was no way to get closer to ball lightning by scientific means. But now, GERD FUSSMANN from the MAX PLANCK INSTITUTE FOR PLASMA PHYSICS and BERLIN'S HUMBOLDT UNIVERSITY has managed to create blazing balls of plasma in his lab - and they may just help explain the phenomenon. (orig.)

  16. The development of cobalt-base alloy ball bearing

    International Nuclear Information System (INIS)

    Yu Xinshui; Chen Jianting; Wang Zaishu; Wang Ximei; Huang Chongming.

    1986-01-01

    The main technologies and experiences in developing a Cobalt-base alloy ball bearing are described. In the hardfacing of bearing races, a lower-hardness alloy of type St-6 is used rather than an alloy with hardness similar to that of the ball and finally the hardness of race is increased to match that of the ball by heat treatment. This improvement has certain advantages. The experience of whole developing technology indicates that strict control of the technology in the bearing-race hardfacing is the key problem in the quality assurance of bearings

  17. Ball lightning with the nonrelativistic electrons of the core

    Science.gov (United States)

    Shmatov, M. L.

    2015-08-01

    The lifetimes, volume densities of energy, electron and ion densities and other parameters of ball lightning cores with the nonrelativistic electrons are estimated. The model according to which the motion of the electrons of the ball lightning core is the superposition of the oscillatory motion and the thermal motion in the directions perpendicular to those of the oscillations is proposed. Some problems related to isolation of the ball lightning core from the atmosphere and the transfer of the atmospheric pressure on it are considered.

  18. Defects Detection on Silicon Nitride Balls by Laser Ultrasonics

    International Nuclear Information System (INIS)

    Lemaire, M.; Ouaftouh, M.; Duquennoy, M.; Jenot, F.; Ourak, M.

    2005-01-01

    In this work, we study the generation and the detection of surface waves on silicon nitride balls a few millimetres in diameter. The excitation of these waves is carried out thanks to a pulsed laser YAG and their detection is achieved with a laser interferometric probe. The whole of the device requires neither coupling nor direct contact with the balls. These waves are then used for the analysis of defects close to the surface of the balls. Several measurements are carried out on samples presenting various defects. Correlation attempts are also carried out between some ultrasonic parameters and some characteristics of defects

  19. Einleitung der Bibliografie "Fußball als Kulturgut"

    OpenAIRE

    Schiffer, Jürgen

    2006-01-01

    "Die Auffassung, dass 'Fußball auch ein Stück Kultur' sei (Beckenbauer zit. von Adelmann et al. 2003), ist alles andere als eine Selbstverständlichkeit. Lange Zeit wurde das Fußballspiel als geistloser 'Proletensport' geschmäht (Herzog 2002). Insbesondere in seinen Anfangszeiten, Ende des 19. Jahrhunderts, sah sich der in Deutschland aufkommende Fußball zahlreichen Attacken ausgesetzt. So beschrieb Karl Planck (1898, repr. 1982) den Fußball in seiner polemischen Schrift, die gegen dieses von ...

  20. Is swimming during pregnancy a safe exercise?

    DEFF Research Database (Denmark)

    Juhl, Mette; Kogevinas, Manolis; Andersen, Per Kragh

    2010-01-01

    BACKGROUND: Exercise in pregnancy is recommended in many countries, and swimming is considered by many to be an ideal activity for pregnant women. Disinfection by-products in swimming pool water may, however, be associated with adverse effects on various reproductive outcomes. We examined...... the association between swimming in pregnancy and preterm and postterm birth, fetal growth measures, small-for-gestational-age, and congenital malformations. METHODS: We used self-reported exercise data (swimming, bicycling, or no exercise) that were prospectively collected twice during pregnancy for 74......,486 singleton pregnancies. Recruitment to The Danish National Birth Cohort took place 1996-2002. Using Cox, linear and logistic regression analyses, depending on the outcome, we compared swimmers with physically inactive pregnant women; to separate a possible swimming effect from an effect of exercise...

  1. Training simulator for teaching a technique to the long transmission of ball in basket-ball by a method by an arcuated hand from above with threaten

    Directory of Open Access Journals (Sweden)

    Charikova K.M.

    2012-03-01

    Full Text Available Technical devices which used in basket-ball are considered. The features of constructing of trainers and method of their application are selected in a training process. A trainer is offered for teaching a technique to the long transmission of ball in basket-ball. A trainer is a moving on a rope imitator of basket-ball ball. This construction allows to design initial position, замах for implementation of transmission and line of acceleration of ball in the final phase of motion. The method of the use of trainer is developed in an educational process.

  2. Birth control pills - progestin only

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000656.htm Birth control pills - progestin only To use the sharing ... have estrogen in them. What Are Progestin Only Birth Control Pills? Birth control pills help keep you ...

  3. Screening Tests for Birth Defects

    Science.gov (United States)

    ... Advocacy For Patients About ACOG Screening Tests for Birth Defects Home For Patients Search FAQs Screening Tests ... FAQ165, April 2014 PDF Format Screening Tests for Birth Defects Pregnancy What is a birth defect? What ...

  4. Prevention: Exercise

    Medline Plus

    Full Text Available ... Strengthen Your Core! Stretching/Flexibility Aerobic Exercise Cervical Exercise Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain Preventing Osteoporosis Back Pain Basics Book RESOURCES ... The Backbone of Spine Treatment Spondylolisthesis BLOG FIND ...

  5. 78 FR 29702 - Ball Bearings and Parts Thereof From Germany: Final Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2013-05-21

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-428-801] Ball Bearings and Parts... administrative review of the antidumping duty order on ball bearings and parts thereof from Germany. The period... ball bearings and parts thereof from Germany as the conclusion of a sunset review. See Ball Bearings...

  6. The head tracks and gaze predicts: how the world's best batters hit the ball

    NARCIS (Netherlands)

    Mann, D.L.; Spratford, W.; Abernethy, B.

    2013-01-01

    Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i) baseball and cricket batters cannot track the ball because it moves

  7. Effects of Varying Ball Bearing Cleaning Processes on Lubricant Life

    National Research Council Canada - National Science Library

    Didziulis, S

    1998-01-01

    The processes used to clean ball bearings and other components in precision spacecraft mechanisms have undergone significant changes to eliminate the use of ozone depleting chemicals, such as Freon TF...

  8. Pink Cricket Balls May Be Visually Challenging at Sunset

    Directory of Open Access Journals (Sweden)

    Joshua M. Adie

    2017-02-01

    Full Text Available Cricket is one of the world’s most popular sports, followed by hundreds of millions of people. It can be dangerous, played with a hard ball flying at great velocities, and accidents have occasionally been fatal. Traditionally, cricket has been played during the day, using a dark red ball. Since the late 1970s, a shorter form of one-day cricket has been played both during the day and at night under floodlights. To overcome visibility issues, one-day cricket uses a white ball, and players wear coloured clothing. There is now a desire to play a traditional form of cricket during the day and at night, using a ‘pink’ ball while players wear white clothing. Concerns regarding visibility, and player and umpire safety, have been raised in this context. Here, we report that these concerns have a sound basis.

  9. Mechanisms of dry ball milling in MOX fabrication

    International Nuclear Information System (INIS)

    Warin, D.; Bauer, M.; Seiss, M.; Lorenzelli, R.

    1997-01-01

    An important stage of MOX fuel pellets fabrication is the blending process of the nuclear powders which is carried out in the French plants in a ball milling and under dry conditions in order to avoid any criticality related difficulties. The milled powders must present a sufficiently intimate distribution of the UO 2 and PuO 2 particles which is necessary to synthesize the homogeneous (UPu)O 2 solid solution during the subsequent reactive sintering; the homogeneity of the UP 2 /PuO 2 fuels is important in relation both to uniform irradiation performance and to solubility during reprocessing. This study is related to the mechanisms which take place inside the ball mill as a function of the nature and size of the balls, the rotation speed, the milling time and the mill-to-ball charge-to-powder volume ratios. 4 refs, 3 figs

  10. On the isoperimetric rigidity of extrinsic minimal balls

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, V.

    2003-01-01

    We consider an m-dimensional minimal submanifold P and a metric R-sphere in the Euclidean space R-n. If the sphere has its center p on P, then it will cut out a well defined connected component of P which contains this center point. We call this connected component an extrinsic minimal R-ball of P....... The quotient of the volume of the extrinsic ball and the volume of its boundary is not larger than the corresponding quotient obtained in the space form standard situation, where the minimal submanifold is the totally geodesic linear subspace R-m. Here we show that if the minimal submanifold has dimension...... larger than 3, if P is not too curved along the boundary of an extrinsic minimal R-ball, and if the inequality alluded to above is an equality for the extrinsic minimal ball, then the minimal submanifold is totally geodesic....

  11. An aerodynamic analysis of recent FIFA world cup balls

    Science.gov (United States)

    Kiratidis, Adrian L.; Leinweber, Derek B.

    2018-05-01

    Drag and lift coefficients of recent FIFA world cup balls are examined. We fit a novel functional form to drag coefficient curves and in the absence of empirical data provide estimates of lift coefficient behaviour via a consideration of the physics of the boundary layer. Differences in both these coefficients for recent balls, which result from surface texture modification, can significantly alter trajectories. Numerical simulations are used to quantify the effect these changes have on the flight paths of various balls. Altitude and temperature variations at recent world cup events are also discussed. We conclude by quantifying the influence these variations have on the three most recent world cup balls, the Brazuca, the Jabulani and the Teamgeist. While our paper presents findings of interest to the professional sports scientist, it remains accessible to students at the undergraduate level.

  12. Sources and components of ball lightning theory

    Science.gov (United States)

    Nikitin, A. I.; Bychkov, V. L.; Nikitina, T. F.; Velichko, A. M.; Abakumov, V. I.

    2018-03-01

    The article describes the cases when ball lightning (BL) exhibited an extremely high specific energy store (up to 1010 J/m3), a presence of uncompensated electric charge (up to 10‑3 C) and an ability to generate high frequency pulses (up to 10 MW). It is shown that the realization of a combination of these properties of BL is possible if to consider it as a heterogeneous system consisting of a unipolarly charged core and a dielectric shell. In the electric field of the core charge, arises a force owing to the polarization of the shell that opposes the Coulomb repulsion force of the charges. BL models constructed according to the indicated principle are described: the electrodynamic model and the chemical-thermal model, which treats BL as a hollow sphere filled with steam. The requirement to take into account the main three properties of BL makes it possible to reduce the number of models of this natural phenomenon. Detailed cases of observations of high-energy lightning are analyzed.

  13. Confirming a case of ball lightening production

    Energy Technology Data Exchange (ETDEWEB)

    Balyberdin, V.V.

    1975-01-01

    Model confirmation of ball lightening production was carried out on a three-cascade unit having a working voltage of 150 kV in an air atmosphere at a pressure of 730 to 750 mg Hg std. with C-shaped bending of the lightening drawoff. The electrical discharge parameters were held constant as follows: maximum current amplitude of 7 kA, oscillatory period of the quenched discharge of 6.5 x 10/sup -6/ sec, and energy used up in the unit approximately 2.2 k joules. Moving pictures are presented of the generation of one long luminous bundle displaced from a solid with a velocity up to 240 m/sec, whose luminosity was observed over a period of approximately 3 x 10/sup -3/ sec. Analysis of the experimental results showed that the appearance of plasma bundles is associated with the development of turbulent flows of a low-temperature plasma near the tip of a solid. (SJR)

  14. The Riddle of Ball Lightning: A Review

    Directory of Open Access Journals (Sweden)

    José Donoso

    2006-01-01

    Full Text Available One of the most intriguing and enduring scientific challenges is to find an explanation for ball lightning, the shining fireballs that sometimes appear near lightning strokes. Although many theoretical ideas have been proposed and much experimental work has been performed, there is not yet an accepted explanation of their amazing properties. They are surprisingly stable, lasting up to 10 s, even minutes in some rare cases. By night, their appearance can be spectacular, but their brilliance is just similar to that of a home electric bulb. Most of the time, their motion is smooth and horizontal, but it can also be erratic and chaotic; they can penetrate indoors through window panes. We review here some of the most discussed approaches, including both theoretical models to find an explanation as well as experimental efforts to reproduce them in the laboratory. We distinguish between chemical and physical models, depending on whether their stability is mainly based on their chemical composition or on purely physical phenomena involving electromagnetic fields and plasmas.

  15. Nano-porous calcium phosphate balls.

    Science.gov (United States)

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Evolution of the Birth Plan

    OpenAIRE

    Kaufman, Tamara

    2007-01-01

    Many birth professionals are discarding the birth plan as an outdated and ineffectual document. This column discusses the past limitations and present uses of the birth plan in an effort to enhance current teaching on how expectant parents can write and use this important document. Encouraging expectant parents to prepare two separate, but corresponding, birth plans—the “Discussion Birth Plan” and the “Hospital Birth Plan”—is proposed. Teaching suggestions and possible implications are explor...

  17. Data interpolation using rational cubic Ball spline with three parameters

    Science.gov (United States)

    Karim, Samsul Ariffin Abdul

    2016-11-01

    Data interpolation is an important task for scientific visualization. This research introduces new rational cubic Ball spline scheme with three parameters. The rational cubic Ball will be used for data interpolation with or without true derivative values. Error estimation show that the proposed scheme works well and is a very good interpolant to approximate the function. All graphical examples are presented by using Mathematica software.

  18. A dynamic styrofoam-ball model for simulating molecular motion

    Science.gov (United States)

    Mak, Se-yuen; Cheung, Derek

    2001-01-01

    In this paper we introduce a simple styrofoam-ball model that can be used for simulating molecular motion in all three states. As the foam balls are driven by a vibrator that is in turn driven by a signal generator, the frequency and the amplitude of vibration can be adjusted independently. Thus, the model is appropriate for simulating molecular motion in the liquid state, which is a combination of vibration and meandering motion.

  19. Attempted - to -Phase Conversion of Croconic Acid via Ball Milling

    Science.gov (United States)

    2017-05-18

    CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 16 19a. NAME OF RESPONSIBLE PERSON Steven W...stainless steel ball and vessel. ................ 6 Fig. 6 Representative heat flow traces for milled CA samples. Curves have been offset to enhance...stainless steel . The ball has a diameter of 6.35 mm and a mass of 1 g; the vessel outer diameter is 12.7 mm, and the vessel length is 27.7 mm. A series

  20. Linearly convergent stochastic heavy ball method for minimizing generalization error

    KAUST Repository

    Loizou, Nicolas

    2017-10-30

    In this work we establish the first linear convergence result for the stochastic heavy ball method. The method performs SGD steps with a fixed stepsize, amended by a heavy ball momentum term. In the analysis, we focus on minimizing the expected loss and not on finite-sum minimization, which is typically a much harder problem. While in the analysis we constrain ourselves to quadratic loss, the overall objective is not necessarily strongly convex.

  1. Brown carbon in tar balls from smoldering biomass combustion

    OpenAIRE

    R. K. Chakrabarty; H. Moosmüller; L.-W. A. Chen; K. Lewis; W. P. Arnott; C. Mazzolen; M. Dubey; C. E. Wold; W. M. Hao; S. M. Kreidenweis

    2010-01-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles – "tar balls" – from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Ångström coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent imaginary part of its refractive index – optically defined as "brown carbon" – is an important component of tar balls. The spectrum of the...

  2. Atmospheric tar balls: aged primary droplets from biomass burning?

    OpenAIRE

    Tóth, A.; Hoffer, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2014-01-01

    Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are produced by the direct emission of liquid tar droplets followed by heat transformation upon biomass burning. For the first time in a...

  3. Effect of Hoop Stress on Ball Bearing Life Prediction

    Science.gov (United States)

    Zaretsky, Erwin V.; August, Richard; Coe, Harold H.

    1995-01-01

    A finite-element analysis (FEA) of a generic, dimensionally normalized inner race of an angular-contact ball bearing was performed under varying conditions of speed and the press (or interference) fit of the inner-race bore on a journal. The FEA results at the ball-race contact were used to derive an equation from which was obtained the radius of an equivalent cylindrical bearing race with the same or similar hoop stress. The radius of the equivalent cylinder was used to obtain a generalized closed-form approximation of the hoop stresses at the ball-inner-race contact in an angular-contact ball bearing. A life analysis was performed on both a 45- and a 120-mm-bore, angular-contact ball bearing. The predicted lives with and without hoop stress were compared with experimental endurance results obtained at 12000 and 25000 rpm with the 120-mm-bore ball bearing. A life factor equation based on hoop stress is presented.

  4. Automatic optical inspection system design for golf ball

    Science.gov (United States)

    Wu, Hsien-Huang; Su, Jyun-Wei; Chen, Chih-Lin

    2016-09-01

    ith the growing popularity of golf sport all over the world, the quantities of relevant products are increasing year by year. To create innovation and improvement in quality while reducing production cost, automation of manufacturing become a necessary and important issue. This paper reflect the trend of this production automa- tion. It uses the AOI (Automated Optical Inspection) technology to develop a system which can automatically detect defects on the golf ball. The current manual quality-inspection is not only error-prone but also very man- power demanding. Taking into consideration the competition of this industry in the near future, the development of related AOI equipment must be conducted as soon as possible. Due to the strong reflective property of the ball surface, as well as its surface dimples and subtle flaws, it is very difficult to take good quality image for automatic inspection. Based on the surface properties and shape of the ball, lighting has been properly design for image-taking environment and structure. Area-scan cameras have been used to acquire images with good contrast between defects and background to assure the achievement of the goal of automatic defect detection on the golf ball. The result obtained is that more than 973 of the NG balls have be detected, and system maintains less than 103 false alarm rate. The balls which are determined by the system to be NG will be inspected by human eye again. Therefore, the manpower spent in the inspection has been reduced by 903.

  5. The fragmented science of ball lightning (with comment).

    Science.gov (United States)

    Turner, D J

    2002-01-15

    All the apparent anomalies in ball lightning behaviour seem to result from electrochemical processes which arise at the surface of a wet air plasma. The structure and stability of an established lightning ball are maintained by these processes and the ball operates as a thermochemical heat pump powered by the electric field of a thunderstorm. Movements result from asymmetries in the various fields which control the structure. In addition to electric, electromagnetic and gravitational fields, temperature, pressure and compositional gradients can be involved. Electrochemistry provides a framework within which specific properties can be considered using better developed or more appropriate disciplines. Several commonly made assumptions and approximations are identified which can be invalid under the specific conditions which favour ball lightning stability. If any of these limitations is ignored, seriously misleading conclusions may result. The range of power associated with lightning balls is ill defined but may vary continuously between that of globes which lack a bright centre and that of normal lightning. Our failure to contain plasmas electrochemically for more than a few seconds probably reflects our inability to balance (or even measure) the various fields which govern a ball's stability. All the fields may need to be controlled before electrochemistry can usefully be employed to contain plasmas.

  6. Atmospheric tar balls: Particles from biomass and biofuel burning

    Science.gov (United States)

    Pósfai, MiháLy; GelencséR, AndráS.; Simonics, RenáTa; Arató, Krisztina; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2004-03-01

    "Tar balls" are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (˜90 mol % carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas-to-particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water-bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.

  7. Birthing postures and birth canal lacerations.

    Science.gov (United States)

    Suzuki, Shunji

    2017-05-01

    This study was performed to assess the differences in the birth canal lacerations following the lateral and fours posture deliveries compared with those following the supine posture deliveries. We examined the birth canal lacerations of our "low risk" pregnant women under the midwife-led delivery care at Japanese Red Cross Katsushika Maternity Hospital between April 2006 and March 2015. There were 3826, 1754 and 719 women who delivered with supine, lateral and fours postures. The rate of no laceration in the women who delivered with lateral posture was significant lower than that in the women who delivered with supine posture (OR 0.630, 95% CI 0.56-0.71, p < 0.01); however, the incidence of perineal laceration in the women who delivered with lateral posture was significant lower than that in the women who delivered with supine posture (OR 0.856, 95% CI 0.76-0.90, p < 0.01). The incidence of perineal laceration of third- or fourth-degree in the women who delivered with fours posture was significant higher than that in the women who delivered with supine posture (OR 2.28, 95% CI 1.2-4.2, p < 0.01). The current results may be to help for self-determination of birthing postures in prenatal women.

  8. Swimming pool use and birth defect risk.

    Science.gov (United States)

    Agopian, A J; Lupo, Philip J; Canfield, Mark A; Mitchell, Laura E

    2013-09-01

    Swimming during pregnancy is recommended. However, the use of swimming pools is also associated with infection by water-borne pathogens and exposure to water disinfection byproducts, which are 2 mechanisms that are suspected to increase risk for birth defects. Thus, we evaluated the relationship between maternal swimming pool use during early pregnancy and risk for select birth defects in offspring. Data were evaluated for nonsyndromic cases with 1 of 16 types of birth defects (n = 191-1829) and controls (n = 6826) from the National Birth Defects Prevention Study delivered during 2000-2006. Logistic regression analyses were conducted separately for each birth defect type. Separate analyses were conducted to assess any pool use (yes vs no) and frequent use (5 or more occasions in 1 month) during the month before pregnancy through the third month of pregnancy. There was no significant positive association between any or frequent pool use and any of the types of birth defects, even after adjustment for several potential confounders (maternal race/ethnicity, age at delivery, education, body mass index, folic acid use, nulliparity, smoking, annual household income, surveillance center, and season of conception). Frequent pool use was significantly negatively associated with spina bifida (adjusted odds ratio, 0.68; 95% confidence interval, 0.47-0.99). Among offspring of women 20 years old or older, pool use was associated with gastroschisis (adjusted odds ratio, 1.3; 95% confidence interval, 1.0-1.8), although not significantly so. We observed little evidence suggesting teratogenic effects of swimming pool use. Because swimming is a common and suggested form of exercise during pregnancy, these results are reassuring. Copyright © 2013 Mosby, Inc. All rights reserved.

  9. Recovering from Birth

    Science.gov (United States)

    ... Know your pregnancy rights Getting ready for baby Birthing, breastfeeding, and parenting classes Breastfeeding Circumcision Health care for baby Making your home safe for baby Last-minute to-dos Childbirth ...

  10. Labor and Birth

    Science.gov (United States)

    ... Know your pregnancy rights Getting ready for baby Birthing, breastfeeding, and parenting classes Breastfeeding Circumcision Health care for baby Making your home safe for baby Last-minute to-dos Childbirth ...

  11. Contraception and Birth Control

    Science.gov (United States)

    ... NICHD Research Information Find a Study More Information Pharmacology Condition Information NICHD Research Information Find a Study ... discuss birth control methods with one’s sexual partner. General methods of contraception include: Barrier —physically interferes with ...

  12. Preterm Labor and Birth

    Science.gov (United States)

    ... NICHD Research Information Find a Study More Information Pharmacology Condition Information NICHD Research Information Find a Study ... Pinterest Email Print Preterm Labor and Birth In general, a normal human pregnancy lasts about 40 weeks, ...

  13. Birth Control Patch

    Science.gov (United States)

    ... Things That Help Feelings Expert Answers Q&A Movies & More for Teens Teens site Sitio para adolescentes ... and effective method of birth control. Most young women who use the patch have no side effects. ...

  14. Hypnotherapy for birth.

    Science.gov (United States)

    Howell, Maggie

    2014-05-01

    There are many misunderstandings about hypnotherapy for birth and how best to support a woman who has chosen to use it. This article brings together experiences of midwives who have attended women in labour using hypnotherapy, and aims to help birth professionals understand a bit more about hypnotherapy and how they can best support women who are using it. It is a personal account from a hypnotherapy trainer reflecting on her encounters with midwives as they share experiences of observing hypnotherapy in action.

  15. Crew Exercise

    Science.gov (United States)

    Rafalik, Kerrie K.

    2017-01-01

    Johnson Space Center (JSC) provides research, engineering, development, integration, and testing of hardware and software technologies for exercise systems applications in support of human spaceflight. This includes sustaining the current suite of on-orbit exercise devices by reducing maintenance, addressing obsolescence, and increasing reliability through creative engineering solutions. Advanced exercise systems technology development efforts focus on the sustainment of crew's physical condition beyond Low Earth Orbit for extended mission durations with significantly reduced mass, volume, and power consumption when compared to the ISS.

  16. Study of Relation between Physical Activity and Preterm Birth

    Directory of Open Access Journals (Sweden)

    Mehran N.

    2012-04-01

    Full Text Available Background and Objectives: Preterm birth is the main cause of neonatal mortality and morbidity and the importance of knowing its causes is clear. Since the effect of physical activity on preterm birth is unknown and its prevention is the priority in health care, we decided to do this study with the aim of determining the relation between physical activity and preterm birth. Methods: In this case-control study, 300 pregnant women delivering in Izadi Hospital in Qom, Iran in the second half of 2008, selected through simple sampling. The data were collected using standard pregnancy physical activity questionnaire that categorizes the physical activity into 4 groups: work activities, home activities, transport activities and fun/exercise activities. The physical activity severity was calculated as MET (Metabolic Equivalence Test. Finally, the data were analyzed using descriptive and analytic (x2 and t test statistics. A p<0.05 was considered as significant.Results: The findings didn't show any significant relation between physical activity and preterm birth. In addition, in view of activity type, fun/exercise and work activities (respectively and in view of activity severity, sedentary and moderate activities (respectively were associated with higher, but insignificant rate of preterm birth. Among demographic factors, only gravidity of women was significantly associated with preterm birth.Conclusion: Although, in this study the significant relation between physical activity and preterm delivery wasn't observed, the same research with further sample is recommended.

  17. Exercise KATRINE

    International Nuclear Information System (INIS)

    Clahane, Darren; Burgoyne, William

    1995-01-01

    Based on a hypothetical incident at the Scottish Nuclear Ltd Torness AGR nuclear power station, Exercise KATRINE was the 1994 national civil nuclear exercise and the biggest simulation of a nuclear accident to take place in Britain last year. The exercise, held on 17 and 18 November, was based on a series of postulated faults which resulted in an uncontrolled release of radioactivity. It commenced at 07.00 on Thursday and continued for about 33 hours, until around 15.30 on Friday. Activity focused on the Torness Off-site Centre (TOSC), in Cockenzie near Edinburgh, and the brand new Torness Media Briefing Centre (TMBC) located nearby. (author)

  18. Theory of operation for the ball rheometer

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, C.L.; Colson, J.B. [Pacific Northwest Lab., Richland, WA (United States); Pasamehmetoglu, K.O.; Unal, C.; Edwards, J.N.; Abbott, J. [Los Alamos National Lab., NM (United States)

    1994-12-01

    The Hanford Site contains over 100 high-volume tanks containing high-level radioactive wastes. The tank which has received the most attention is Tank 101-SY, which is a double shell tank containing a caustic mixed-waste slurry. The ball rheometer developed in this work is intended at least initially for application in this tank. Tank 101-SY is known to periodically release flammable and toxic gases during events known as rollovers. The tank waste is largely made up of two layers, a supernatant liquid layer underneath which is a thick sludge layer. The two layers are called the convective (C) and the nonconvective (NC) regions, so called because of the thermal transport properties ascribed to each. Although they have significant uncertainty, the current theology data suggest the existence of a yield stress in the highly viscous nonconvective layer. Gas generated in the waste can be held in the NC layer if the material yield strength or its viscosity is high enough. Gas cannot be held in the C layer to any appreciable extent unless it is in solution. As gas continues to be generated by chemical or other processes, the number of gas bubbles and/or their sizes increases in the NC layer. A rollover occurs when the amount of gas trapped in the nonconvective region becomes great enough to overcome forces holding it in place. These forces are believed to be dependent on the theology of the nonconvective region and perhaps the bubble surface tension. The buoyancy forces on the bubbles exceed the restraining forces arising from the yield stress and the viscosity of the NC layer. Theology is then seen to be quite important in determining the nature of gas release events in this tank.

  19. Quenching simulation of steel grinding balls

    Directory of Open Access Journals (Sweden)

    Zapata-Hernández, Oscar

    2015-09-01

    Full Text Available The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.Las transformaciones de fase en aceros de alto carbono durante su temple y un posterior periodo de estabilización fueron modelizadas por medio del uso de paquetes computacionales basados en el método del elemento finito y de la transformación cinética de los aceros. El modelo se usó para predecir los cambios de temperatura y microestructura que se presentan en bolas de dos diferentes tamaños empleadas en estaciones de molienda de minerales. Se encontró una buena correlación entre las temperaturas medidas mediante la inserción de termopares y aquellas predichas por el modelo una vez que se modificó la conductividad térmica del acero en el intervalo mixto de fases. La predicción de las transformaciones de fase se confirmó a través del análisis metalográfico.

  20. THE BEHAVIOURAL REACTION OF WEANERS TO HANGING TOYS: WOODEN BALL AND AROMATIZED WOODEN BALL – WAY TO REDUCE AGGRESSION AFTER MIXING

    Directory of Open Access Journals (Sweden)

    Jacek NOWICKI

    2008-05-01

    Full Text Available The behaviour of weaners after mixing housed in pens equipped with hanging wooden ball, aromatized with vanilla fluid hanging wooden ball and without enrichment was evaluated. It was found that both enrichments reduced aggression, however the most interesting for weaners was the aromatized wooden ball.

  1. Compulsive exercise

    DEFF Research Database (Denmark)

    Lichtenstein, Mia Beck; Hinze, Cecilie Juul; Emborg Jannsen, Bolette

    2017-01-01

    Compulsive exercise is a condition described since 1970s. It is characterized by a craving for physical training, resulting in uncontrollable excessive exercise behavior with harmful consequences, such as injuries and impaired social relations. It has not been accepted as a mental disorder...... found that compulsive exercise is associated with eating disorder pathology, perfectionism, neuroticism, narcissism, and obsessive compulsive traits. The most prominent negative consequences were injuries, social impairment, and depression, but more research is needed to uncover the potential...... dysfunction resulting from compulsive exercise. As the condition is not recognized as a psychiatric disorder, studies on treatment interventions are sparse. Problems with compliance have been reported; therefore, motivational interviewing has been proposed as a treatment approach, in combination...

  2. Prevention: Exercise

    Medline Plus

    Full Text Available ... 15 repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing resistance. It can be done with weights (hand-held ...

  3. Prevention: Exercise

    Medline Plus

    Full Text Available ... Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/Flexibility Aerobic ... Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back Pain Preventing Osteoporosis Back Pain ...

  4. Prevention: Exercise

    Medline Plus

    Full Text Available ... Pain Other Scoliosis Back Pain and Emotional Distress Muscle Spasms Pinched Nerve Discitis Degenerative Conditions Bulge vs ... exercise focus on core strengthening, or building the muscles that provide support for your body. Pilates, yoga ...

  5. Prevention: Exercise

    Medline Plus

    Full Text Available ... done with quick short movements, or slow full movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall ...

  6. Prevention: Exercise

    Medline Plus

    Full Text Available ... Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! ... in a straight line. Hold for 10 seconds working towards 30 seconds. Repeat 1-5 times or ...

  7. Prevention: Exercise

    Medline Plus

    Full Text Available ... legs to touch the wall, keeping hips and knees bent. Use your hips to push your body ... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall ...

  8. Prevention: Exercise

    Medline Plus

    Full Text Available ... Epidural Steroid Injections Lumbar Zygapophysical (Facet) Joint Injections PREVENTION Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! ...

  9. Prevention: Exercise

    Medline Plus

    Full Text Available ... Transverse Core Strengthening This strengthens the muscles that cross from your ribs across your waist and helps ... repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing ...

  10. Prevention: Exercise

    Medline Plus

    Full Text Available ... arts all provide well-rounded core strengthening programs. Simple exercises can be done at home as well. ... be done with weights (hand-held or training machines) or using isometric techniques. Common household items (like ...

  11. Prevention: Exercise

    Medline Plus

    Full Text Available ... and Education Injection Treatments for Spinal Pain Epidural Steroid Injections Lumbar Zygapophysical (Facet) Joint Injections PREVENTION Lifestyle ... Z Spine Specialists Videos 9 for Spine Epidural Steroid Injections Exercise: The Backbone of Spine Treatment Spondylolisthesis ...

  12. Prevention: Exercise

    Medline Plus

    Full Text Available ... Pregnancy and Back Pain Preventing Osteoporosis Back Pain Basics Book RESOURCES Patient ... popular forms of exercise focus on core strengthening, or building the muscles that provide support for your body. Pilates, yoga and martial arts ...

  13. Prevention: Exercise

    Medline Plus

    Full Text Available ... Jordan Gliedt, DC Directional Exercises Electrothermal Modalities Ergonomic Changes Hydrotherapy Manual Therapy Physical Therapy Postural Training Traction Watchful Waiting and Education Injection Treatments for Spinal Pain Epidural Steroid Injections ...

  14. Prevention: Exercise

    Medline Plus

    Full Text Available ... Lifestyle Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! ... hand-held or training machines) or using isometric techniques. Common household items (like small canned goods) can ...

  15. Prevention: Exercise

    Medline Plus

    Full Text Available ... repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing resistance. It can be done with weights (hand-held or training machines) or using isometric techniques. Common household items ( ...

  16. Prevention: Exercise

    Medline Plus

    Full Text Available ... exercise focus on core strengthening, or building the muscles that provide support for your body. Pilates, yoga ... doing it. Transverse Core Strengthening This strengthens the muscles that cross from your ribs across your waist ...

  17. Prevention: Exercise

    Medline Plus

    Full Text Available ... Choices 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/ ... something providing resistance. It can be done with weights (hand-held or training machines) or using isometric ...

  18. Prevention: Exercise

    Medline Plus

    Full Text Available ... isometric exercise to strengthen your neck. Press your palm against your forehead, then use your neck muscles to push against your palm. Hold for ten seconds and repeat six times. ...

  19. Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

    Directory of Open Access Journals (Sweden)

    Monajati Alireza

    2017-12-01

    Full Text Available The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53 and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63 at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70% between 60 to 40° of the knee angle and then decreased to 27% of the maximal isometric voluntary contraction at the end of movement. Overall, the biceps femoris and semitendinosus showed similar patterns of activation. In conclusion, even though the hamstring muscle activation at open knee positions was similar between exercises, the Nordic Curl elicited a higher hamstring activity compared to the Ball Leg Curl.

  20. Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

    Science.gov (United States)

    Monajati, Alireza; Larumbe-Zabala, Eneko; Goss-Sampson, Mark

    2017-01-01

    Abstract The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of the knee angle and then decreased to 27% of the maximal isometric voluntary contraction at the end of movement. Overall, the biceps femoris and semitendinosus showed similar patterns of activation. In conclusion, even though the hamstring muscle activation at open knee positions was similar between exercises, the Nordic Curl elicited a higher hamstring activity compared to the Ball Leg Curl. PMID:29339983

  1. A systematic review of core implementation components in team ball sport injury prevention trials.

    Science.gov (United States)

    O'Brien, James; Finch, Caroline F

    2014-10-01

    Recently, the use of specific exercise programmes to prevent musculoskeletal injuries in team ball sports has gained considerable attention, and the results of large-scale, randomised controlled trials have supported their efficacy. To enhance the translation of these interventions into widespread use, research trials must be reported in a way that allows the players, staff and policymakers associated with sports teams to implement these interventions effectively. In particular, information is needed on core implementation components, which represent the essential and indispensable aspects of successful implementation. To assess the extent to which team ball sport injury prevention trial reports have reported the core implementation components of the intervention, the intervention target and the use of any delivery agents (ie, staff or other personnel delivering the intervention). To summarise which specific types of intervention, intervention target and delivery agents are reported. To develop consensus between reviewers on the reporting of these components. Six electronic databases were systematically searched for English-language, peer-reviewed papers on injury prevention exercise programme (IPEP) trials in team ball sports. The reporting of all eligible trials was assessed by two independent reviewers. The reporting of the three core implementation components were coded as 'yes', 'no' or 'unclear'. For cases coded as 'yes', the specific types of interventions, intervention targets and delivery agents were extracted and summarised. The search strategy identified 52 eligible trials. The intervention and the intervention target were reported in all 52 trials. The reporting of 25 trials (48%) specified the use of delivery agents, the reporting of three trials (6%) specified not using delivery agents, and in the reporting of the remaining 24 trials (46%) the use of delivery agents was unclear. The reported intervention type was an IPEP alone in 43 trials (83

  2. Ethics and "normal birth".

    Science.gov (United States)

    Lyerly, Anne Drapkin

    2012-12-01

    The concept of "normal birth" has been promoted as ideal by several international organizations, although debate about its meaning is ongoing. In this article, I examine the concept of normalcy to explore its ethical implications and raise a trio of concerns. First, in its emphasis on nonuse of technology as a goal, the concept of normalcy may marginalize women for whom medical intervention is necessary or beneficial. Second, in its emphasis on birth as a socially meaningful event, the mantra of normalcy may unintentionally avert attention to meaning in medically complicated births. Third, the emphasis on birth as a normal and healthy event may be a contributor to the long-standing tolerance for the dearth of evidence guiding the treatment of illness during pregnancy and the failure to responsibly and productively engage pregnant women in health research. Given these concerns, it is worth debating not just what "normal birth" means, but whether the term as an ideal earns its keep. © 2012, Copyright the Authors Journal compilation © 2012, Wiley Periodicals, Inc.

  3. Birth Order and Child Health

    OpenAIRE

    Lundberg, Evelina; Svaleryd, Helena

    2017-01-01

    Previous research has established that birth order affects outcomes such as educational achievements, IQ and earnings. The mechanisms behind these effects are, however, still largely unknown. In this paper, we examine birth-order effects on health, and whether health at young age could be a transmission channel for birth-order effects observed later in life. We find no support for the birth-order effect having a biological origin; rather firstborns have worse health at birth. This disadvantag...

  4. Effect of soccer shoe upper on ball behaviour in curve kicks

    Science.gov (United States)

    Ishii, Hideyuki; Sakurai, Yoshihisa; Maruyama, Takeo

    2014-08-01

    New soccer shoes have been developed by considering various concepts related to kicking, such as curving a soccer ball. However, the effects of shoes on ball behaviour remain unclear. In this study, by using a finite element simulation, we investigated the factors that affect ball behaviour immediately after impact in a curve kick. Five experienced male university soccer players performed one curve kick. We developed a finite element model of the foot and ball and evaluated the validity of the model by comparing the finite element results for the ball behaviour immediately after impact with the experimental results. The launch angle, ball velocity, and ball rotation in the finite element analysis were all in general agreement with the experimental results. Using the validated finite element model, we simulated the ball behaviour. The simulation results indicated that the larger the foot velocity immediately before impact, the larger the ball velocity and ball rotation. Furthermore, the Young's modulus of the shoe upper and the coefficient of friction between the shoe upper and the ball had little effect on the launch angle, ball velocity, and ball rotation. The results of this study suggest that the shoe upper does not significantly influence ball behaviour.

  5. Effect of Ball Weight on Speed, Accuracy, and Mechanics in Cricket Fast Bowling

    Directory of Open Access Journals (Sweden)

    Katharine L. Wickington

    2017-02-01

    Full Text Available The aims of this study were: (1 to quantify the acute effects of ball weight on ball release speed, accuracy, and mechanics in cricket fast bowling; and (2 to test whether a period of sustained training with underweight and overweight balls is effective in increasing a player’s ball release speed. Ten well-trained adult male cricket players performed maximum-effort deliveries using balls ranging in weight from 46% to 137% of the standard ball weight (156 g. A radar gun, bowling target, and 2D video analysis were used to obtain measures of ball speed, accuracy, and mechanics. The participants were assigned to either an intervention group, who trained with underweight and overweight balls, or to a control group, who trained with standard-weight balls. We found that ball speed decreased at a rate of about 1.1 m/s per 100 g increase in ball weight. Accuracy and bowling mechanics were not adversely affected by changes in ball weight. There was evidence that training with underweight and overweight balls might have produced a practically meaningful increase in bowling speed (>1.5 m/s in some players without compromising accuracy or increasing their risk of injury through inducing poor bowling mechanics. In cricket fast bowling, a wide range of ball weight might be necessary to produce an effective modified-implement training program.

  6. James L. Tuck Los Alamos ball lightning pioneer

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.A.

    1999-07-01

    James Tuck was well known for starting the Project Sherwood group at Los Alamos Scientific Laboratory in 1952. This group was formed to study and develop concepts for controlled fusion energy. In his later years after retiring from Controlled Fusion Division, he continued research at Los Alamos on the topic of ball lightning. He traveled widely giving lectures on both observations of others and his own experimental efforts. He collected anecdotal observations obtained from those in his lecture audiences during his travels and from responses from newspaper articles where he asked for specific information from ball lightning observers. He finally cut off this collection of data when the number of responses became overwhelming. The author's primary publication on ball lightning was a short laboratory report. He planned on publishing a book on the subject but this was never completed before his death. Tuck focused his experimental effort on attempting to duplicate the production of plasma balls claimed to be observed in US Navy submarines when a switch was opened under overload conditions with battery power. During lunch breaks he made use of a Los Alamos N-division battery bank facility to mock up a submarine power pack and switch gear. This non-funded effort was abruptly terminated when an explosion occurred in the facility. An overview of Tuck's research and views will be given. The flavor Jim's personality as well as a ball produced with his experimental apparatus will be shown using video chips.

  7. Characterization and Infrared Emission Spectroscopy of Ball Plasmoid Discharges

    Science.gov (United States)

    Dubowsky, Scott E.; McCall, Benjamin J.

    2015-06-01

    Plasmas at atmospheric pressure serve many purposes, from ionization sources for ambient mass spectrometry (AMS) to plasma-assisted wound healing. Of the many naturally occurring ambient plasmas, ball lightning is one of the least understood; there is currently no solid explanation in the literature for the formation and lifetime of natural ball lightning. With the first measurements of naturally occurring ball lightning being reported last year, we have worked to replicate the natural phenomenon in order to elucidate the physical and chemical processes by which the plasma is sustained at ambient conditions. We are able to generate ball-shaped plasmoids (self-sustaining plasmas) that are analogous to natural ball lightning using a high-voltage, high-current, pulsed DC system. Improvements to the discharge electronics used in our laboratory and characterization of the plasmoids that are generated from this system will be described. Infrared emission spectroscopy of these plasmoids reveals emission from water and hydroxyl radical -- fitting methods for these molecular species in the complex experimental spectra will be presented. Rotational temperatures for the stretching and bending modes of H2O along with that of OH will be presented, and the non-equilibrium nature of the plasmoid will be discussed in this context. Cen, J.; Yuan, P,; Xue, S. Phys. Rev. Lett. 2014, 112, 035001. Dubowsky, S.E.; Friday, D.M.; Peters, K.C.; Zhao, Z.; Perry, R.H.; McCall, B.J. Int. J. Mass Spectrom. 2015, 376, 39-45.

  8. Reliability of a New Medicine Ball Throw Power Test.

    Science.gov (United States)

    Sayers, Mark G L; Bishop, Stephen

    2017-08-01

    The purpose of this study was to examine the reliability of a new upper body medicine ball push-press (MBP-P) test. Twenty-three strength trained volunteers performed a series of supine MBP-P throws using loads representing 5% and10% of their 5RM bench press (5 repetitions at each load). Throws were performed on a force platform (2000 Hz), with medicine ball kinematic data collected using a high-speed motion capture (500 Hz). Testing was repeated after 7-10 days to quantify intertest reliability. Maximal force (F max ), impulse at F max , time to F max , and maximum rate of force development (RFD max ) were all calculated from the force platform outputs, with maximum ball velocity (Vel max ) and maximum ball acceleration (Accel max ) developed from the kinematic data. Reliability was assessed using intraclass correlation (ICC), coefficient of variation (%CV), and typical error. Medicine ball kinematic variables were more reliable (CV% = 2.6-5.3, ICC = 0.87-0.95) than the various force platform derived power variables (CV% = 7.9-26.7, ICC = 0.51-0.90). The MBP-P test produces reliable data and can be used to quantify many standard power based measures, with the key findings have implications for athletic populations requiring high velocity, light load upper body pushing power.

  9. New data on the formation of Carboniferous coal balls

    Energy Technology Data Exchange (ETDEWEB)

    Scott, A.C.; Mattey, D.P.; Howard, R. [University of London, Egham (United Kingdom). Royal Holloway and Bedford New College, Dept. of Geology

    1996-10-01

    Coal balls are formed from the precipitation of carbonate minerals, predominantly calcite, from water during or immediately post-peat formation. Previous petrological studies suggest permineralization occurred at various stages during the peatificiation process by precipitation from a mixture of marine and meteoric freshwater. The geochemical studies reported here aimed to test previous theories of coal ball formation. The coal balls studied are from Upper Carboniferous and Carboniferous/Permian coal seams in Britain, United States of America, Belgium and China. Stable carbon isotopic values of calcites range from {delta}{sup 13}C of -5 to -35 parts per thousand indicating highly variable contribution of decayed organic matter to the carbonate cement. Oxygen isotopic values of delta({sup 18}) range from -3 to -15 parts per thousand suggest both marine and meteoric freshwater sources. The range, in the British coal balls in particular, with {delta}{sup 13}C ranging from -7 to -25 parts per thousand indicates the complexity of carbonate generation. Isotopic data support at least four theories of carbonate coal ball formation. This makes their absence from post-Permian coals the more puzzling and it is suggested that the overall structure of the peat may play a role.

  10. The coefficient of restitution of pressurized balls: a mechanistic model

    Science.gov (United States)

    Georgallas, Alex; Landry, Gaëtan

    2016-01-01

    Pressurized, inflated balls used in professional sports are regulated so that their behaviour upon impact can be anticipated and allow the game to have its distinctive character. However, the dynamics governing the impacts of such balls, even on stationary hard surfaces, can be extremely complex. The energy transformations, which arise from the compression of the gas within the ball and from the shear forces associated with the deformation of the wall, are examined in this paper. We develop a simple mechanistic model of the dependence of the coefficient of restitution, e, upon both the gauge pressure, P_G, of the gas and the shear modulus, G, of the wall. The model is validated using the results from a simple series of experiments using three different sports balls. The fits to the data are extremely good for P_G > 25 kPa and consistent values are obtained for the value of G for the wall material. As far as the authors can tell, this simple, mechanistic model of the pressure dependence of the coefficient of restitution is the first in the literature. *%K Coefficient of Restitution, Dynamics, Inflated Balls, Pressure, Impact Model

  11. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  12. Atmospheric tar balls: aged primary droplets from biomass burning?

    Science.gov (United States)

    Tóth, A.; Hoffer, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2014-07-01

    Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are produced by the direct emission of liquid tar droplets followed by heat transformation upon biomass burning. For the first time in atmospheric chemistry we generated tar-ball particles from liquid tar obtained previously by dry distillation of wood in an all-glass apparatus in the laboratory with the total exclusion of flame processes. The particles were perfectly spherical with a mean optical diameter of 300 nm, refractory, externally mixed, and homogeneous in the contrast of the transmission electron microscopy (TEM) images. They lacked any graphene-like microstructure and exhibited a mean carbon-to-oxygen ratio of 10. All of the observed characteristics of laboratory-generated particles were very similar to those reported for atmospheric tar-ball particles in the literature, strongly supporting our hypothesis regarding the formation mechanism of atmospheric tar-ball particles.

  13. Prevention of preterm birth.

    LENUS (Irish Health Repository)

    Flood, Karen

    2012-02-01

    Preterm birth (delivery before 37 completed weeks of gestation) is common and rates are increasing. In the past, medical efforts focused on ameliorating the consequences of prematurity rather than preventing its occurrence. This approach resulted in improved neonatal outcomes, but it remains costly in terms of both the suffering of infants and their families and the economic burden on society. Increased understanding of the pathophysiology of preterm labor has altered the approach to this problem, with increased focus on preventive strategies. Primary prevention is a limited strategy which involves public education, smoking cessation, improved nutritional status and avoidance of late preterm births. Secondary prevention focuses on recurrent preterm birth which is the most recognisable risk factor. Widely accepted strategies include cervical cerclage, progesterone and dedicated clinics. However, more research is needed to explore the role of antibiotics and anti-inflammatory treatments in the prevention of this complex problem.

  14. Birth room images

    DEFF Research Database (Denmark)

    Bowden, Calida; Sheehan, Athena; Foureur, Maralyn Jean

    2016-01-01

    and implications for practice: as images on the Internet inform and persuade society about stereotypical behaviours, the trends of our time and sociocultural norms, it is important to recognise images of the technological birth room on the Internet may be influential in dictating women's attitudes, choices......Objective: this study examined images of birth rooms in developed countries to analyse the messages and visual discourse being communicated through images. Design: a small qualitative study using Kress and van Leeuwen's (2006) social semiotic theoretical framework for image analysis, a form...... of discourse analysis. Setting/participants: forty images of birth rooms were collected in 2013 from Google Images, Flickr, Wikimedia Commons and midwifery colleagues. The images were from obstetric units, alongside and freestanding midwifery units located in developed countries (Australia, Canada, Europe, New...

  15. Genomics of Preterm Birth

    Science.gov (United States)

    Swaggart, Kayleigh A.; Pavlicev, Mihaela; Muglia, Louis J.

    2015-01-01

    The molecular mechanisms controlling human birth timing at term, or resulting in preterm birth, have been the focus of considerable investigation, but limited insights have been gained over the past 50 years. In part, these processes have remained elusive because of divergence in reproductive strategies and physiology shown by model organisms, making extrapolation to humans uncertain. Here, we summarize the evolution of progesterone signaling and variation in pregnancy maintenance and termination. We use this comparative physiology to support the hypothesis that selective pressure on genomic loci involved in the timing of parturition have shaped human birth timing, and that these loci can be identified with comparative genomic strategies. Previous limitations imposed by divergence of mechanisms provide an important new opportunity to elucidate fundamental pathways of parturition control through increasing availability of sequenced genomes and associated reproductive physiology characteristics across diverse organisms. PMID:25646385

  16. Cerebral oxygenation after birth

    DEFF Research Database (Denmark)

    Hessel, Trine W; Hyttel-Sorensen, Simon; Greisen, Gorm

    2014-01-01

    AIM: To compare absolute values of regional cerebral tissue oxygenation (cStO2 ) during haemodynamic transition after birth and repeatability during steady state for two commercial near-infrared spectroscopy (NIRS) devices. METHODS: In a prospective observational study, the INVOS 5100C and FORE......: The INVOS and FORE-SIGHT cStO2 estimates showed oxygenation-level-dependent difference during birth transition. The better repeatability of FORE-SIGHT could be due to the lower response to change in saturation....

  17. Exercise stress test

    Science.gov (United States)

    ... exercise treadmill; Stress ECG; Exercise electrocardiography; Stress test - exercise treadmill; CAD - treadmill; Coronary artery disease - treadmill; Chest pain - treadmill; Angina - treadmill; Heart disease - ...

  18. Rotating and rolling rigid bodies and the "hairy ball" theorem

    Science.gov (United States)

    Bormashenko, Edward; Kazachkov, Alexander

    2017-06-01

    Rotating and rolling rigid bodies exemplify a fascinating theorem of topology, jokingly called the "hairy ball" theorem, which demands that any continuous tangent vector field on the sphere has at least one point where the field is zero. We demonstrate via a gedanken experiment how drilling through a rotating ball, thereby converting it into a torus, leads to the elimination of zero-velocity points on the ball surface. Using the same reasoning, zero-velocity points can be removed from the surface of a drilled spinning top. We discuss the location of zero-velocity points on the surfaces of rigid bodies rolling with no slip and with slip. Observations made from different reference frames identify various zero-velocity points. Illustrative experiments visualizing zero-velocity points are presented.

  19. Durability Tests of Ball Valve Prototype with Flowmeter Operation

    Science.gov (United States)

    Rogula, J.; Romanik, G.

    2018-02-01

    The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

  20. Acoustic monitoring of a ball sinking in vibrated granular sediments

    Science.gov (United States)

    van den Wildenberg, Siet; Léopoldès, Julien; Tourin, Arnaud; Jia, Xiaoping

    2017-06-01

    We develop an ultrasound probing to investigate the dynamics of a high density ball sinking in 3D opaque dense granular suspensions under horizontal weak vibrations. We show that the motion of the ball in these horizontally vibrated glass bead packings saturated by water is consistent with the frictional rheology. The extracted stress-strain relation evidences an evolution of flow behaviour from frictional creep to inertial regimes. Our main finding is that weak external vibration primarily affects the yield stress and controls the depth of sinking via vibration-induced sliding at the grain contact. Also, we observe that the extracted rheological parameters depend on the size of the probing ball, suggesting thus a non-local rheology.

  1. Simulating fullerene ball bearings of ultra-low friction

    International Nuclear Information System (INIS)

    Li Xiaoyan; Yang Wei

    2007-01-01

    We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C 60 and C 20 ) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of 5.283 x 10 -7 and 6.768 x 10 -7 nN/atom for C 60 and C 20 bearings) and energy dissipation (lowest dissipation per cycle of 0.013 and 0.016 meV/atom for C 60 and C 20 bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings

  2. A Case of Lung Lesions Induced by a soccer Ball

    Directory of Open Access Journals (Sweden)

    Masaaki Takemoto

    2013-01-01

    Full Text Available An 18-year-old youth soccer forward received a direct hit from a kicked soccer ball on the anterior right chest when the goal keeper kicked the ball from a distance of 1 meter. Immediately following the hit, the subject experienced dypnea, chest pain and had a cough, with several milliliters of hemoptysis. His symptoms subsided after 20 minutes of rest. However, he still felt mild discomfort and was taken to our department for evaluation. On examination, all vital signs were normal. A computed tomography scan of the chest was obtained, and revealed a small area of opacification in the right lung field suggesting a pulmonary contusion or traumatic lung edema. Ten days after the initial injury, he was cleared for full participation. We herein reported the first case of a lung lesion induced by a soccer ball. Conservative treatment resulted in a favorable outcome.

  3. Study on the luminous characteristics of a natural ball lightning

    Science.gov (United States)

    Wang, Hao; Yuan, Ping; Cen, Jianyong; Liu, Guorong

    2018-02-01

    According to the optical images of the whole process of a natural ball lightning recorded by two slit-less spectrographs in the Qinghai plateau of China, the simulated observation experiment on the luminous intensity of the spherical light source was carried out. The luminous intensity and the optical power of the natural ball lightning in the wavelength range of 400-690 nm were estimated based on the experimental data and the Lambert-Beer Law. The results show that the maximum luminous intensity was about 1.24 × 105 cd in the initial stage of the natural ball lightning, and the maximum luminous intensity and the maximum optical power in most time of its life were about 5.9 × 104 cd and 4.2 × 103 W, respectively.

  4. Supermassive dark-matter Q-balls in galactic centers?

    Energy Technology Data Exchange (ETDEWEB)

    Troitsky, Sergey [Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary Prospect 7a, Moscow 117312 (Russian Federation); Moscow Institute for Physics and Technology,Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation)

    2016-11-11

    Though widely accepted, it is not proven that supermassive compact objects (SMCOs) residing in galactic centers are black holes. In particular, the Milky Way’s SMCO can be a giant nontopological soliton, Q-ball, made of a scalar field: this fits perfectly all observational data. Similar but tiny Q-balls produced in the early Universe may constitute, partly or fully, the dark matter. This picture explains in a natural way, why our SMCO has very low accretion rate and why the observed angular size of the corresponding radio source is much smaller than expected. Interactions between dark-matter Q-balls may explain how SMCOs were seeded in galaxies and resolve well-known problems of standard (non-interacting) dark matter.

  5. Comparison of exit time moment spectra for extrinsic metric balls

    DEFF Research Database (Denmark)

    Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente

    2012-01-01

    We prove explicit upper and lower bounds for the $L^1$-moment spectra for the Brownian motion exit time from extrinsic metric balls of submanifolds $P^m$ in ambient Riemannian spaces $N^n$. We assume that $P$ and $N$ both have controlled radial curvatures (mean curvature and sectional curvature......, respectively) as viewed from a pole in $N$. The bounds for the exit moment spectra are given in terms of the corresponding spectra for geodesic metric balls in suitably warped product model spaces. The bounds are sharp in the sense that equalities are obtained in characteristic cases. As a corollary we also...... obtain new intrinsic comparison results for the exit time spectra for metric balls in the ambient manifolds $N^n$ themselves....

  6. The Energy Cost of Running with the Ball in Soccer.

    Science.gov (United States)

    Piras, Alessandro; Raffi, Milena; Atmatzidis, Charalampos; Merni, Franco; Di Michele, Rocco

    2017-11-01

    Running with the ball is a soccer-specific activity frequently used by players during match play and training drills. Nevertheless, the energy cost (EC) of on-grass running with the ball has not yet been determined. The purpose of this study was therefore to assess the EC of constant-speed running with the ball, and to compare it with the EC of normal running. Eight amateur soccer players performed two 6- min runs at 10 km/h on artificial turf, respectively with and without the ball. EC was measured with indirect calorimetry and, furthermore, estimated with a method based on players' accelerations measured with a GPS receiver. The EC measured with indirect calorimetry was higher in running with the ball (4.60±0.42 J/kg/m) than in normal running (4.19±0.33 J/kg/m), with a very likely moderate difference between conditions. Instead, a likely small difference was observed between conditions for EC estimated from GPS data (4.87±0.07 vs. 4.83±0.08 J/kg/m). This study sheds light on the energy expenditure of playing soccer, providing relevant data about the EC of a typical soccer-specific activity. These findings may be a reference for coaches to precisely determine the training load in drills with the ball, such as soccer-specific circuits or small-sided games. © Georg Thieme Verlag KG Stuttgart · New York.

  7. Note: A 1-m Foucault pendulum rolling on a ball

    Science.gov (United States)

    Salva, H. R.; Benavides, R. E.; Venturino, J. A.; Cuscueta, D. J.; Ghilarducci, A. A.

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  8. Field-ball milling induced anisotropy in magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Poudyal, Narayan [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altuncevahir, Baki [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chakka, Vamsi [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chen Kanghua [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Black, Truman D [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Liu, J Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ding, Yong [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2004-12-21

    Nd{sub 2}Fe{sub 14}B and Sm{sub 2}Co{sub 17} particles of submicrometre sizes have been prepared by ball milling in a magnetic field. Structural and magnetic characterization reveal that these submicrometre particles milled in a magnetic field, consisting of nanosize grains, exhibit strong magnetic anisotropy compared with the particles milled without a magnetic field. Based on in situ observations of the field-ball milling in a transparent container, the mechanism of field-induced anisotropy in the nanostructured hard magnetic particles is discussed. (rapid communication)

  9. Evidence of microscopic ball lightning in cold fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, E.H. [PO Box 2013, Champaign, IL 61825 (United States)

    2006-07-01

    There is evidence of microscopic ball lightning in several methods of cold fusion and transmutation. Thus far the experiments of Matsumoto, Miley, Shoulders, Savvatimova, and Urutskoev et al. have shown evidence of these objects that range in size from sub-atomic to about 1 mm in diameter. This article presents pictures and evidence collected by these groups, summarizes the evidence found by other groups, and discusses the significance of microscopic ball lightning. The implications for atomic physics and physics in general are discussed. (author)

  10. Ball lightning as a force-free magnetic knot

    Science.gov (United States)

    Ranada; Soler; Trueba

    2000-11-01

    The stability of fireballs in a recent model of ball lightning is studied. It is shown that the balls shine while relaxing in an almost quiescent expansion, and that three effects contribute to their stability: (i) the formation in each one during a process of Taylor relaxation of a force-free magnetic field, a concept introduced in 1954 in order to explain the existence of large magnetic fields and currents in stable configurations of astrophysical plasmas; (ii) the so called Alfven conditions in magnetohydrodynamics; and (iii) the approximate conservation of the helicity integral. The force-free fields that appear are termed "knots" because their magnetic lines are closed and linked.

  11. Ball lightning dynamics and stability at moderate ion densities

    Science.gov (United States)

    Morrow, R.

    2017-10-01

    A general mechanism is presented for the dynamics and structure of ball lightning and for the maintenance of the ball lightning structure for several seconds. Results are obtained using a spherical geometry for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions and negative ions coupled with Poisson’s equation. A lightning strike can generate conditions in the lightning channel with a majority of positive nitrogen ions, and a minority of negative oxygen ions and electrons. The calculations are initiated with electrons included; however, at the moderate ion densities chosen the electrons are rapidly lost to form negative ions, and after 1 µs their influence on the ion dynamics is negligible. Further development after 1 µs is followed using a simpler set of equations involving only positive ions and negative ions, but including ion diffusion. The space-charge electric field generated by the majority positive ions drives them from the centre of the distribution and drives the minority negative ions and electrons towards the centre of the distribution. In the central region the positive and negative ion distributions eventually overlap exactly and their space-charge fields cancel resulting in zero electric field, and the plasma ball formed is quite stable for a number of seconds. The formation of such plasma balls is not critically dependent on the initial diameter of the ion distributions, or the initial density of minority negative ions. The ion densities decrease relatively slowly due to mutual neutralization of positive and negative ions. The radiation from this neutralization process involving positive nitrogen ions and negative oxygen ions is not sufficient to account for the reported luminosity of ball lightning and some other source of luminosity is shown to be required; the plasma ball model used could readily incorporate other ions in order to account for the luminosity and range of colours reported for ball

  12. Spin Rate and Deflection Ratio of a Ping Pong Ball

    Directory of Open Access Journals (Sweden)

    Byung Joon Ahn

    2013-12-01

    Full Text Available To investigate the effects of a spherical object’s spin rate on the curvature of its flight, Ping Pong balls, of varying spin rates, were hit horizontally and recorded from above with a high-speed camera. It was shown that there was a proportional relationship between the ball’s spin rate and deflection ratio. Additionally, using the results of the analyzed data, a coefficient of skin friction of the Ping Pong ball was found to be approximately 0.2 under the specific conditions of this investigation.

  13. Spin Rate and Deflection Ratio of a Ping Pong Ball

    Directory of Open Access Journals (Sweden)

    Byung Joon Ahn

    2013-01-01

    Full Text Available To investigate the effects of a spherical object’s spin rate on the curvature of its flight, Ping Pong balls, of varying spin rates, were hit horizontally and recorded from above with a high-speed camera. It was shown that there was a proportional relationship between the ball’s spin rate and deflection ratio. Additionally, using the results of the analyzed data, a coefficient of skin friction of the Ping Pong ball was found to be approximately 0.2 under the specific conditions of this investigation.

  14. Ball Lens Fiber Optic Sensor based Smart Handheld Microsurgical Instrument.

    Science.gov (United States)

    Song, Cheol; Gehlbach, Peter L; Kang, Jin U

    2013-03-20

    During freehand performance of vitreoretinal microsurgery the surgeon must perform precise and stable maneuvers that achieve surgical objectives and avoid surgical risk. Here, we present an improved smart handheld microsurgical tool which is based on a ball lens fiber optic sensor that utilizes common path swept source optical coherence tomography. Improvements include incorporation of a ball lens single mode fiber optic probe that increases the working angle of the tool to greater than 45 degrees; and increases the magnitude of the distance sensing signal through water. Also presented is a cutting function with an improved ergonomic design.

  15. Image enlargement using biharmonic Said-Ball surface

    Science.gov (United States)

    Saaban, A.; Kherd, A.; Jameel, A. F.; Akhadkulov, H.; Alipiah, F. M.

    2017-09-01

    This paper discusses the use of biharmonic cubic Said-Ball surfaces in image enlargement area. Resizing an image through up sampling or down sampling is generally common for making smaller image fit a bigger screen in full screen mode or reducing a higher resolution image to a smaller resolution. However due to some limitation, this paper will focus on image enlargement based on scaling factor of two. We use biharmonic cubic Said-Ball subject to a given four boundary curves condition respectively. We implement and evaluate the performance of the proposed method based on peak signal to noise ratio (PSNR) indicator using well-known gray-scale test images.

  16. Note: A 1-m Foucault pendulum rolling on a ball.

    Science.gov (United States)

    Salva, H R; Benavides, R E; Venturino, J A; Cuscueta, D J; Ghilarducci, A A

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  17. Trunk muscle electromyographic activity with unstable and unilateral exercises.

    Science.gov (United States)

    Behm, David G; Leonard, Allison M; Young, Warren B; Bonsey, W Andrew C; MacKinnon, Scott N

    2005-02-01

    The purpose of this cross-sectional study was to evaluate the effect of unstable and unilateral resistance exercises on trunk muscle activation. Eleven subjects (6 men and 5 women) between 20 and 45 years of age participated. Six trunk exercises, as well as unilateral and bilateral shoulder and chest presses against resistance, were performed on stable (bench) and unstable (Swiss ball) bases. Electromyographic activity of the upper lumbar, lumbosacral erector spinae, and lower-abdominal muscles were monitored. Instability generated greater activation of the lower-abdominal stabilizer musculature (27.9%) with the trunk exercises and all trunk stabilizers (37.7-54.3%) with the chest press. There was no effect of instability on the shoulder press. Unilateral shoulder press produced greater activation of the back stabilizers, and unilateral chest press resulted in higher activation of all trunk stabilizers, when compared with bilateral presses. Regardless of stability, the superman exercise was the most effective trunk-stabilizer exercise for back-stabilizer activation, whereas the side bridge was the optimal exercise for lower-abdominal muscle activation. Thus, the most effective means for trunk strengthening should involve back or abdominal exercises with unstable bases. Furthermore, trunk strengthening can also occur when performing resistance exercises for the limbs, if the exercises are performed unilaterally.

  18. Birth Order Debate Resolved?

    Science.gov (United States)

    Zajonc, R. B.

    2001-01-01

    Critiques Rodgers et al.'s June 2000 research on the relation between birth order and intelligence, which suggests that it is a methodological illusion. Explains how the intellectual environment and the teaching function (whereby older children tutor younger ones) contribute to the growth of intellectual maturity, the first negatively and the…

  19. Finding Autonomy in Birth*

    Science.gov (United States)

    Kukla, Rebecca; Kuppermann, Miriam; Little, Margaret; Lyerly, Anne Drapkin; Mitchell, Lisa M; Armstrong, Elizabeth M.; Harris, Lisa

    2009-01-01

    Over the last several years, as cesarean deliveries have grown increasingly common, there has been a great deal of public and professional interest in the phenomenon of women ‘choosing’ to deliver by cesarean section in the absence of any specific medical indication. The issue has sparked intense conversation, as it raises questions about the nature of autonomy in birth. Whereas mainstream bioethical discourse is used to associating autonomy with having a large array of choices, this conception of autonomy does not seem adequate to capture concerns and intuitions that have a strong grip outside of this discourse. An empirical and conceptual exploration of how delivery decisions ought to be negotiated must be guided by a rich understanding of women’s agency and its placement within a complicated set of cultural meanings and pressures surrounding birth. It is too early to be ‘for’ or ‘against’ women’s access to cesarean delivery in the absence of traditional medical indications - and indeed, a simple pro- or con- position is never going to do justice to the subtlety of the issue. The right question is not whether women ought to be allowed to choose their delivery approach, but rather, taking the value of women’s autonomy in decision-making around birth as a given, what sorts of guidelines, practices, and social conditions will best promote and protect women’s full inclusion in a safe and positive birth process. PMID:19076937

  20. Better Births Initiative

    African Journals Online (AJOL)

    Ensuring that health professionals practise according to evidence-based standards is important since it affects the quality and cost of care patients receive. The purpose of this research was to use a focused change programme (the Better Births Initiative) to influence obstetric practice at 10 hospitals in Gauteng, South Africa.

  1. Eccentric exercise

    DEFF Research Database (Denmark)

    Kjaer, Michael; Heinemeier, Katja Maria

    2014-01-01

    Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive...... to differences in type and/or amount of mechanical stimulus with regard to expression of collagen, regulatory factors for collagen, and cross-link regulators. In overused (tendinopathic) human tendon, eccentric exercise training has a beneficial effect, but the mechanism by which this is elicited is unknown...

  2. Vibrating vaginal balls to improve pelvic floor muscle performance in women after childbirth: a protocol for a randomised controlled feasibility trial.

    Science.gov (United States)

    Oblasser, Claudia; McCourt, Christine; Hanzal, Engelbert; Christie, Janice

    2016-04-01

    This paper presents a feasibility trial protocol the purpose of which is to prepare for a future randomised controlled trial to determine the effectiveness of vibrating vaginal pelvic floor training balls for postpartum pelvic floor muscle rehabilitation. Vibrating vaginal pelvic floor training balls are available in Austria to enhance women's pelvic floor muscles and thus prevent or treat urinary incontinence and other pelvic floor problems following childbirth. Nonetheless, there is currently little empirical knowledge to substantiate their use or assess their relative effectiveness in comparison to current standard care, which involves pelvic floor muscle exercises. Single blind, randomised controlled feasibility trial with two parallel groups. It is planned to recruit 56 postpartum women in Vienna, who will be randomised into one of two intervention groups to use either vibrating vaginal balls or a comparator pelvic floor muscle exercises for 12 weeks. As this is a feasibility study, study design features (recruitment, selection, randomisation, intervention concordance, data collection methods and tools) will be assessed and participants' views and experiences will be surveyed. Tested outcome measures, collected before and after the intervention, will be pelvic floor muscle performance as reported by participants and measured by perineometry. Descriptive and inferential statistics and content analysis will serve the preparation of the future trial. The results of this feasibility trial will inform the design and conduct of a full randomised controlled trial and provide insight into the experiences of women regarding the interventions and study participation. © 2015 John Wiley & Sons Ltd.

  3. Exercise at Home

    Science.gov (United States)

    ... Home Health Insights Exercise & Weight Exercise at Home Exercise at Home Make an Appointment Ask a Question ... with the movement and contact your provider. Posture Exercises Better posture means better breathing and movement. Axial ...

  4. Exercise-Induced Bronchoconstriction

    Science.gov (United States)

    ... Conditions & Treatments ▸ Conditions Dictionary ▸ Exercise-Induced Bronchoconstriction Share | Exercise-Induced Bronchoconstriction (EIB) « Back to A to Z Listing Exercise-Induced Bronchoconstriction, (EIB), often known as exercise-induced ...

  5. Exercise and age

    Science.gov (United States)

    ... to notice the benefits, including improved sleep and self-esteem. Exercise and physical activity can also: Improve or ... many exercises fit into more than one category: AEROBIC EXERCISE Aerobic exercise increases your breathing and heart ...

  6. Diabetes and exercise

    Science.gov (United States)

    Exercise - diabetes; Exercise - type 1 diabetes; Exercise - type 2 diabetes ... a bracelet or necklace that says you have diabetes. Tell coaches and exercise partners that you have diabetes. Always have fast- ...

  7. Effect of panel shape of soccer ball on its flight characteristics

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2014-05-01

    Soccer balls are typically constructed from 32 pentagonal and hexagonal panels. Recently, however, newer balls named Cafusa, Teamgeist 2, and Jabulani were respectively produced from 32, 14, and 8 panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball, named Brazuca, was produced from six panels and will be used in the 2014 FIFA World Cup in Brazil. There have, however, been few studies on the aerodynamic properties of balls constructed from different numbers and shapes of panels. Hence, we used wind tunnel tests and a kick-robot to examine the relationship between the panel shape and orientation of modern soccer balls and their aerodynamic and flight characteristics. We observed a correlation between the wind tunnel test results and the actual ball trajectories, and also clarified how the panel characteristics affected the flight of the ball, which enabled prediction of the trajectory.

  8. Identification of sources of tar balls deposited along the Goa coast, India, using fingerprinting techniques

    Digital Repository Service at National Institute of Oceanography (India)

    Suneel, V.; Vethamony, P.; Zakaria, M.P.; Naik, B.G.; Prasad, K.V.

    Deposition of tar balls along the coast of Goa, India is a common phenomenon during the southwest monsoon. Representative tar ball samples collected from various beaches of Goa and one Bombay High (BH) crude oil sample were subjected to fingerprint...

  9. Noninvasive medical management of fungus ball uropathy in a premature infant.

    Science.gov (United States)

    Alkalay, A L; Srugo, I; Blifeld, C; Komaiko, M S; Pomerance, J J

    1991-09-01

    Unilateral renal obstruction secondary to fungus balls is described in a premature infant. Noninvasive medical management, which included amphotericin B and 5-flucytosine therapy and forced diuresis, resulted in disappearance of fungus balls and resolution of the obstruction.

  10. Prevention: Exercise

    Medline Plus

    Full Text Available ... 10 Tips for a Healthy Back Smoking Weight Patient Safety Exercise Strengthening Strengthen Your Core! Stretching/Flexibility Aerobic ... Strength Training for the Elderly Other Back Pack Safety Pregnancy and Back ... Patient Information Feature Articles Patient Q&A Success Stories ...

  11. Compulsive Exercise

    Science.gov (United States)

    ... Medical help is necessary to resolve the physical problems associated with overexercising before they cause long-term damage to the body. Make a Positive Change Girls and guys who exercise compulsively may have a distorted body image and low self-esteem. They may see themselves as overweight or out ...

  12. Prevention: Exercise

    Medline Plus

    Full Text Available ... building the muscles that provide support for your body. Pilates, yoga and martial arts all provide well-rounded core strengthening programs. Simple exercises can be done at home as well. Some specific core strengthening ... your hips to push your body back to a standing position, then extend your ...

  13. Prevention: Exercise

    Medline Plus

    Full Text Available ... lift chest area. This can be done with quick short movements, or slow full movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall drawn in, ...

  14. Prevention: Exercise

    Science.gov (United States)

    ... lift chest area. This can be done with quick short movements, or slow full movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall drawn in, ...

  15. Exercise gaming

    DEFF Research Database (Denmark)

    Smaerup, M.; Grönvall, E.; Larsen, S. B.

    2017-01-01

    with computer-assisted home training. The interviews evolved around themes, such as the elderly participants' self-efficacy, motivation and acceptance of the technology. Results Age was not an excuse for the modest exercise compliance. The participants were basically self-efficient and accepted the technology...

  16. Prevention: Exercise

    Medline Plus

    Full Text Available ... Information Feature Articles Patient Q&A Success Stories Definitions Anatomy of the Spine Definitions A-Z Spine Specialists Videos 9 for Spine Epidural Steroid Injections Exercise: The Backbone of Spine Treatment Spondylolisthesis BLOG FIND A SPECIALIST Prevention ...

  17. Evacuation exercise

    CERN Multimedia

    AUTHOR|(CDS)2094367

    2017-01-01

    In the event of an emergency, it is important that staff and visitors are evacuated safely and efficiently. Hence CERN organises regularly emergency response and evacuation exercise (also known as an ‘evacuation drill’) in different buildings across the sites.

  18. Planned Out-of-Hospital Birth and Birth Outcomes

    Science.gov (United States)

    Snowden, Jonathan M.; Tilden, Ellen L.; Snyder, Janice; Quigley, Brian; Caughey, Aaron B.; Cheng, Yvonne W.

    2016-01-01

    Background The frequency of planned out-of-hospital birth in the United States has increased in recent years. The value of studies assessing the perinatal risks of planned out-of-hospital birth versus hospital birth has been limited by cases in which transfer to a hospital is required and a birth that was initially planned as an out-of-hospital birth is misclassified as a hospital birth. Methods We performed a population-based, retrospective cohort study of all births that occurred in Oregon during 2012 and 2013 using data from newly revised Oregon birth certificates that allowed for the disaggregation of hospital births into the categories of planned in-hospital births and planned out-of-hospital births that took place in the hospital after a woman’s intrapartum transfer to the hospital. We assessed perinatal morbidity and mortality, maternal morbidity, and obstetrical procedures according to the planned birth setting (out of hospital vs. hospital). Results Planned out-of-hospital birth was associated with a higher rate of perinatal death than was planned in-hospital birth (3.9 vs. 1.8 deaths per 1000 deliveries, P = 0.003; odds ratio after adjustment for maternal characteristics and medical conditions, 2.43; 95% confidence interval [CI], 1.37 to 4.30; adjusted risk difference, 1.52 deaths per 1000 births; 95% CI, 0.51 to 2.54). The odds for neonatal seizure were higher and the odds for admission to a neonatal intensive care unit lower with planned out-of-hospital births than with planned in-hospital birth. Planned out-of-hospital birth was also strongly associated with unassisted vaginal delivery (93.8%, vs. 71.9% with planned in-hospital births; P<0.001) and with decreased odds for obstetrical procedures. Conclusions Perinatal mortality was higher with planned out-of-hospital birth than with planned in-hospital birth, but the absolute risk of death was low in both settings. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human

  19. THE EFFECT OF GAMES AND TRAINING PROGRAMS OFFERED AT BALL SCHOOL (BALSCHULE, ON BALL-COORDINATION AMONG FIRST AND SECOND GRADE STUDENTS

    Directory of Open Access Journals (Sweden)

    Behrooz Ebrahimi

    2013-06-01

    Full Text Available The aim of this study is to investigate the effect of games and training programs offered at the Ball school (Ballschule Heidelberg, on ball-coordination among first and second grade students. For this purpose, 38 students from 13 schools covered by the Ball school (Heidelberg Balschule, were chosen as the experimental group (non-random ; in the meantime the consent of the students’ parents were also received. Forty students as well as a control group (non-random of eight normal schools were selected with parental consents. Then through using ball-coordination tests [BKT (BallKoordinationstests. Ball Coordination’s Tests], the level of the ball skills among both groups were measured in the pre-test and Post-test. Tests included kicking ball against the wall (under five conditions. The research methods were semi-experimental with experimental and control groups. Independent variables were also applied to the experimental group and the means and standard deviations were calculated through descriptive statistics. And then, a T-test for statistical analysis of data in related groups were applied. The results showed a significant effect of games and training programs offered at the school ball in the ball-coordination of subjects.

  20. Births: Final Data for 2012

    Science.gov (United States)

    ... characteristics. Data are presented for maternal age, live-birth order, race and Hispanic origin, marital status, attendant at ... and fertility rates are presented by age, live-birth order, race and Hispanic origin, and marital status. Selected ...

  1. Birth control - slow release methods

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007555.htm Birth control - slow release methods To use the sharing features on this page, please enable JavaScript. Certain birth control methods contain man-made forms of hormones. ...

  2. A jelly model for a ball of an extremely hot plasma

    OpenAIRE

    Kornyushin, Yuri

    2007-01-01

    A simple model is applied to study a high temperature rather dense plasma ball. It is assumed that the ions and delocalized electrons are distributed uniformly throughout the ball, and extra/missing charge is found in a thin layer on the surface of a ball. It is shown in the framework of this model that regarded plasma ball can be relatively stable as a metastable state. Calculations show that electrostatic forces, repulsive forces between the ions, and atmospheric pressure can provide stabil...

  3. Multiple collisions of two steel balls in a Newton’s cradle

    Science.gov (United States)

    Cross, Rod

    2018-03-01

    Multiple collisions of two steel balls in a Newton’s cradle were filmed in order to measure the coefficient of restitution of the balls. Two different initial conditions were examined, one where the balls approached each other at about the same speed, and one where one ball was initially at rest. In theory, the fractional energy loss per collision is different in each case, but the experimental results indicated that the overall energy loss was about the same in both cases.

  4. Consumer Acceptance of Seaweed Ball (Eucheuma Cottonii) Fortified with Catfish Protein Concentrate (Pangasius Hypophthalmus)

    OpenAIRE

    Naibaho, Marianche F; ', Dewita; ', Edison

    2014-01-01

    The study was conducted to evaluate consumer acceptance of seaweed ball fortified with catfish protein concentrate . About 5 kg seaweed was taken from a fish market in Pekanbaru. Three types of seaweed balls were prepared from seaweed flour which was fortificated respectively with 5%, 10%, and 15% catfish protein concentrate. The seaweed balls were evaluated for consumer acceptance and chemical composition. The results indicate that the seaweed balls added with 15% catfish protein concentrate...

  5. Ball milling and annealing of Co-50 at% W Powders

    CSIR Research Space (South Africa)

    Bolokang, AS

    2013-04-01

    Full Text Available annealing of unmilled compacts yielded metastable phases. Upon 10 and 20 h ball milling of Co-W powder, no alloying was obtained. Although milling did not yield significant crystal changes in W and Co ground state struc- tures, its effect is evident during...

  6. Catching fly balls: a simulation study of the Chapman strategy

    NARCIS (Netherlands)

    Kistemaker, D.A.; Faber, H.; Beek, P.J.

    2009-01-01

    Chapman [Chapman, S. (1968). Catching a baseball. American Journal of Physics, 36, 868-870] showed that a catcher may be guided to the landing spot of a fly ball by zeroing out its optical acceleration. Subsequently, various studies have provided evidence for what is now known as the Chapman

  7. Ball game watching theory in the teaching site

    Science.gov (United States)

    Liu, Shugang; Li, Xiufang; Chuang, Chin-Jung

    2017-08-01

    Lecturing is a common approach in the traditional teaching site. In this paper, we bring a modern model "ball game watching theory" to explain the situation in the classroom. The reason why the audiences going to the court is to enjoy the atmosphere, and it is also the reason why student joining to the class. A successful class running is to create studious atmosphere. However, once the teacher does the demo in the class, the multimedia tool must be used to show the details, as the big display working in the court. The key moment is recorded and the details are magnified. when teaching aids are demonstrated, the multimedia tool plays an important role. The attention of students walks between the teacher and the display. In this ball game watching theory, the demonstrate experience is like the ball game, and the teacher works as an anchor. By following the demonstration proceeding, students build the knowledge by themselves. In addition, the demonstration must be designed to be interesting in order to make the class proceed fluently. The similarity between the ball game watching and the class will be discussed. Finally we suggest a modern class design which can raise learner motivation and achievement.

  8. Fuzzy controller for better tennis ball robot | Nguyen | Journal of ...

    African Journals Online (AJOL)

    This paper aims at designing a tennis ball robot as a training facility for tennis players. The robot is built with fuzzy controller which provides proper techniques for the players to gain practical experience as well as technical skills; thus, it can effectively serve the community and train athletes in the high-performance sport.

  9. Preliminary Studies on the Development of Meat Balls | Igene ...

    African Journals Online (AJOL)

    The UUFB sample was rated highest in terms of overall likeness and may economically complement some of the existing popular meat-based snacks in Nigeria. The significance of the study is discussed. @JASEM Keyterms: Meat, Meat ball, Quality, Product development. J. Appl. Sci. Environ. Manage. June, 2012, Vol.

  10. The spectacle of the ball python (Python regius)

    DEFF Research Database (Denmark)

    Da Silva, Mari-Ann Otkjær; Heegaard, Steffen; Wang, Tobias

    2014-01-01

    A detailed morphological description of the spectacle of the ball python (Python regius) is provided. The eyes of 21 snakes were examined by light microscopy and/or transmission electron microscopy. Additionally, eyes of nine live snakes were examined using optical coherence tomography (OCT) and ...

  11. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    Alumina balls worn out ( 14.2 × 10 − 1 mm 3 ) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their bettertribological properties ...

  12. Preparation of iron sulphides by high energy ball milling

    DEFF Research Database (Denmark)

    Lin, R.; Jiang, Jianzhong; Larsen, R.K.

    1998-01-01

    The reaction of a powder mixture consisting of 50 a.% Fe and 50 a.% S during high energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. After around 19 h of milling FeS2 and FeS havebeen formed. By further milling the FeS compound becomes dominating and only Fe...

  13. Structural and magnetic properties of ball milled copper ferrite

    DEFF Research Database (Denmark)

    Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

    1998-01-01

    The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces ca...

  14. Precession of a Spinning Ball Rolling down an Inclined Plane

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle a to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, µ, must be at least tan a. The situation is similar for the case of a ball rolling down an inclined plane. In order…

  15. Rock Characteristics and Ball Mill Energy Requirements at ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... rate, power draw and ball mill performance. The rock types identified were conglomerate and quartzite and the main minerals were quartz, feldspars, iron oxides and sulphides. Mineralogical analysis classified the ores into hard, medium and soft. There were little differences in the mineral constituents of the ...

  16. Predicting brain acceleration during heading of soccer ball

    Science.gov (United States)

    Taha, Zahari; Hasnun Arif Hassan, Mohd; Azri Aris, Mohd; Anuar, Zulfika

    2013-12-01

    There has been a long debate whether purposeful heading could cause harm to the brain. Studies have shown that repetitive heading could lead to degeneration of brain cells, which is similarly found in patients with mild traumatic brain injury. A two-degree of freedom linear mathematical model was developed to study the impact of soccer ball to the brain during ball-to-head impact in soccer. From the model, the acceleration of the brain upon impact can be obtained. The model is a mass-spring-damper system, in which the skull is modelled as a mass and the neck is modelled as a spring-damper system. The brain is a mass with suspension characteristics that are also defined by a spring and a damper. The model was validated by experiment, in which a ball was dropped from different heights onto an instrumented dummy skull. The validation shows that the results obtained from the model are in a good agreement with the brain acceleration measured from the experiment. This findings show that a simple linear mathematical model can be useful in giving a preliminary insight on what human brain endures during a ball-to-head impact.

  17. High-Energy Ball-Milling of Alloys and Compounds

    International Nuclear Information System (INIS)

    Le Caer, G.; Delcroix, P.; Begin-Colin, S.; Ziller, T.

    2002-01-01

    After outlining some characteristics of high-energy ball-milling, we discuss selected examples of phase transformation and of alloy synthesis which focus on deviations from archetypal behaviours and throw light on the milling mechanisms. Some contributions of Moessbauer spectrometry to the characterization of ground materials are described.

  18. Design optimization of deep groove ball bearings using crowding ...

    Indian Academy of Sciences (India)

    Aparna Duggirala

    2018-02-07

    Feb 7, 2018 ... Abstract. This paper presents a crowding distance particle swarm optimization technique to optimize the design parameters of deep groove ball bearings. The design optimization problem is multi-objective in nature. The considered objectives are maximizing dynamic and static load bearing capacities and ...

  19. Differential effects of thermal and chemical stressors on tissue balls ...

    African Journals Online (AJOL)

    Coral cell aggregates (tissue balls) from four species (Acropora muricata, Fungia repanda, Pavona cactus and Pocillopora damicornis) were used as an indicator to investigate the effects on the corals of thermal stress and of chemical extracts from three sponges (Adocia sp., Haliclona sp. and Lissodendoryx sp.) and one ...

  20. Eric Cantona: Fußball-Ikone der modernen Medienwelt

    Directory of Open Access Journals (Sweden)

    Martin Wassermair

    2010-03-01

    Full Text Available In Unterhaltungsindustrie und Massenmedien nimmt der Sport eine im wahrsten Sinne des Wortes bewegende Rolle ein. Er ist zugleich Wettkampf-Arena und Wunschmaschine, Werbefläche und Starproduktion. Dass die Erscheinungsformen des Sports in der modernen Medienwelt einer rasanten Dynamik und Wechselbeziehung unterliegen, ist am Beispiel des Massenphänomens Fußballs vielleicht am deutlichsten abzulesen.

  1. Development of Microcontroller-Based Ball and Beam Trainer Kit

    Directory of Open Access Journals (Sweden)

    Gunawan Dewantoro

    2015-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE A ball and beam trainer kit based on microcontroller was developed for teaching control system course for the sophomore students. This specially-purposed kit consists of a ball located on a beam with a fixed axle at one of its end. At the other end, a servomotor was employed to control the position of the ball by adjusting the rotation angle of the servomotor. Seven predetermined positions were set to 10, 20, 30, 40, 50, 60, and 70 cm relative to the fixed axle of the beam. The Proportional-Integral-Derivative (PID scheme was then used to compensate the error. This kit is equipped with a user interface to configure controller coefficients, select the set points, plot the actual ball position, and display parameter values. The user interface program runs on PC or notebook connected to microcontroller via serial communications. A questionnaire-based assessment about the use of this kit was conducted by 17 students taking the course, giving a rating value of 94.12%.

  2. Brown carbon in tar balls from smoldering biomass combustion

    Science.gov (United States)

    R. K. Chakrabarty; H. Moosmuller; L.-W. A. Chen; K. Lewis; W. P. Arnott; C. Mazzoleni; M. K. Dubey; C. E. Wold; W. M. Hao; S. M. Kreidenweis

    2010-01-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles - "tar balls" - from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Angstrom coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent...

  3. An earthworm-like robot using origami-ball structures

    Science.gov (United States)

    Fang, Hongbin; Zhang, Yetong; Wang, K. W.

    2017-04-01

    Earthworms possess extraordinary on-ground and underground mobility, which inspired researchers to mimic their morphology characteristics and locomotion mechanisms to develop crawling robots. One of the bottlenecks that constrain the development and wide-spread application of earthworm-like robots is the process of design, fabrication and assembly of the robot frameworks. Here we present a new earthworm-like robot design and prototype by exploring and utilizing origami ball structures. The origami ball is able to antagonistically output both axial and radial deformations, similar as an earthworm's body segment. The origami folding techniques also introduce many advantages to the robot development, including precise and low cost fabrication and high customizability. Starting from a flat polymer film, we adopt laser machining technique to engrave the crease pattern and manually fold the patterned flat film into an origami ball. Coupling the ball with a servomotor-driven linkage yields a robot segment. Connecting six segments in series, we obtain an earthworm-like origami robot prototype. The prototype is tested in a tube to evaluate its locomotion performance. It shows that the robot could crawl effectively in the tube, manifesting the feasibility of the origami-based design. In addition, test results indicate that the robot's locomotion could be tailored by employing different peristalsis-wave based gaits. The robot design and prototype reported in this paper could foster a new breed of crawling robots with simply design, fabrication, and assemble processes, and improved locomotion performance.

  4. Thump, ring: the sound of a bouncing ball

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J I, E-mail: katz@wuphys.wustl.ed [Department of Physics and McDonnell Center for the Space Sciences, Washington University, St Louis, MO 63130 (United States)

    2010-07-15

    A basketball bounced on a stiff surface produces a characteristic loud thump, followed by a high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms.

  5. Article Commentary: Activity in Pregnancy for Patients with a History of Preterm Birth

    Directory of Open Access Journals (Sweden)

    Nichelle Satterfield

    2016-01-01

    Full Text Available Preterm birth remains a leading cause of neonatal morbidity and mortality throughout the world. Numerous risk factors for preterm birth have been identified, including non-Hispanic black race, a variety of social and behavioral factors, infections, and history of a prior preterm delivery. Of these, a history of prior spontaneous preterm birth is one of the strongest risk factors. Traditionally, women with a history of preterm birth or those deemed at high risk for preterm delivery have been placed on bed rest or a reduced activity regimen during their pregnancy. However, there is little evidence to support this recommendation. Recent research has suggested that regular physical activity and exercise during pregnancy is safe and does not increase the risk of preterm delivery. Therefore, physicians should encourage women with a history of preterm birth to exercise throughout pregnancy according to guidelines published by the American College of Obstetricians and Gynecologists as long as they are receiving regular prenatal care and their current health status permits exercise. However, there are no randomized controlled trials evaluating exercise prescription in women with a history of preterm birth, hence additional research is needed in this area.

  6. Screening for spontaneous preterm birth

    NARCIS (Netherlands)

    van Os, M.A.; van Dam, A.J.E.M.

    2015-01-01

    Preterm birth is the most important cause of perinatal morbidity and mortality worldwide. In this thesis studies on spontaneous preterm birth are presented. The main objective was to investigate the predictive capacity of mid-trimester cervical length measurement for spontaneous preterm birth in a

  7. Visual strategies underpinning the development of visual-motor expertise when hitting a ball

    NARCIS (Netherlands)

    Sarpeshkar, Vishnu; Abernethy, B.; Mann, D.L.

    2017-01-01

    It is well known that skilled batters in fast-ball sports do not align their gaze with the ball throughout ball-flight, but instead adopt a unique sequence of eye and head movements that contribute toward their skill. However, much of what we know about visual-motor behavior in hitting is based on

  8. On phenomenon of light radiation from miniature balls immersed in water

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P., E-mail: v_torchigin@mail.r [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278, Moscow (Russian Federation); Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278, Moscow (Russian Federation)

    2010-01-11

    A phenomenon of light radiation from miniature silicon balls produced at arc discharge and immersed in water is described. Video film showing shining balls in a vessel with water is presented. An explanation of this phenomenon is considered. Similarities and differences of this phenomenon with a phenomenon of ball lightning are analyzed.

  9. On phenomenon of light radiation from miniature balls immersed in water

    Science.gov (United States)

    Torchigin, V. P.; Torchigin, A. V.

    2010-01-01

    A phenomenon of light radiation from miniature silicon balls produced at arc discharge and immersed in water is described. Video film showing shining balls in a vessel with water is presented. An explanation of this phenomenon is considered. Similarities and differences of this phenomenon with a phenomenon of ball lightning are analyzed.

  10. Rolling Motion of a Ball Spinning about a Near-Vertical Axis

    Science.gov (United States)

    Cross, Rod

    2012-01-01

    A ball that is projected forward without spin on a horizontal surface will slide for a short distance before it starts rolling. Sliding friction acts to decrease the translation speed v and it acts to increase the rotation speed [omega]. When v = R[omega], where R is the ball radius, the ball will start rolling and the friction force drops almost…

  11. 78 FR 33975 - Safety Zone; Flagship Niagara Mariners Ball Fireworks, Presque Isle Bay, Erie, PA

    Science.gov (United States)

    2013-06-06

    ...-AA00 Safety Zone; Flagship Niagara Mariners Ball Fireworks, Presque Isle Bay, Erie, PA AGENCY: Coast... Presque Isle Bay during the Flagship Niagara Mariners Ball Fireworks display. This temporary safety zone... the Flagship Niagara Mariners Ball Fireworks. This zone will be effective and enforced from 9:30 p.m...

  12. 78 FR 9674 - Ball Bearings and Parts Thereof From Germany: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2013-02-11

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-428-801] Ball Bearings and Parts... antidumping duty order on ball bearings and parts thereof from Germany. The period of review (POR) is May 1... at less than normal value. \\1\\ On September 15, 2011, the Department revoked the order on ball...

  13. 27 CFR 25.293 - Record of ballings and alcohol content.

    Science.gov (United States)

    2010-04-01

    ... TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Records and Reports § 25.293 Record of ballings... the ballings and the alcohol content of beer and cereal beverage transferred for bottling and racking, between breweries in bulk conveyances, and to pilot brewing plants. Records showing ballings and alcohol...

  14. New Delhi Birth Cohort

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. New Delhi Birth Cohort. In childhood Less than 1% were obese (IOTF 30 kg/m2). Mean BMI SD ranged from –0.4 to –1.0 (CDC). At 26-32 years 10% were obese (BMI >30 kg/m2). ~50% overweight (BMI > 25 kg/m2);. ~65% overweight (BMI > 23 kg/m2). 10% had IGT.

  15. Birth defects surveillance in China.

    Science.gov (United States)

    Dai, Li; Zhu, Jun; Liang, Juan; Wang, Yan-Ping; Wang, He; Mao, Meng

    2011-11-01

    Birth defects are a global public health problem because of their large contribution to infant mortalities and disabilities. It is estimated that 4%-6% of Chinese newborns are affected by birth defects every year. Surveillance is a basic approach to understanding the occurrence and associated factors of birth defects. The Ministry of Health of China initiated a national hospital-based birth defects monitoring system 20 years ago. Nearly every province in this country has established its own surveillance system in the past. The authors reviewed the result of the monitoring system at different administrative levels in China. Available publications on the surveillance of birth defects and data from national and provincial birth defects surveillance systems were reviewed to evaluate the effectiveness of the surveillance systems. According to the 2009 data, the national hospital-based birth defects surveillance system monitored over 1.3 million births, which accounted for more than 8% of births in China. In addition, 30 provincial hospital-based surveillance programs covered a birth population of more than 3.6 million (22% of births in China). Great achievements have been made in terms of case ascertainment, data quality control, and online reporting. But the surveillance systems in China still have some limitations. A short ascertainment period may miss some internal anomalies, inherited metabolic diseases, and malformed fetus aborted before the 28th gestational week. Discrepancies in antenatal or postnatal diagnosis of birth defects between surveillance institutes may affect the detection rate and introduce biases. Absence of baseline data and lack of integrated database systems limit the application of surveillance data to etiological studies and affect the process of decision-making. The surveillance system for birth defects is prerequisite to propose, conduct and assess any interventions for the disease. To meet the need of study and prevention of birth defects

  16. Historiografia del “Ball de Torrent”: De la moixiganga barroca al quadre de balls populars valencians (1692-1929

    Directory of Open Access Journals (Sweden)

    Raül Sanchis Francés

    2013-06-01

    Full Text Available Resum: El Ball de Torrent és una moixiganga dramàtica popular escenificada a la ciutat de València i altres indrets del País Valencià des de finals del segle XVII fins a principis del segle XX. Estava organitzada per agrupacions gremials, juntes d’hospitals o clavaris de festes i protagonitzada per personatges agrupats en comparses que representaven una paròdia sobre les relacions entre les estructures de poder i les classes populars. Tot i la variabilitat segons el moment històric, es conforma com una mescla de quadres amb danses, música i jocs teatrals. El ball interacciona de diverses formes amb algunes festes valencianes i és, probablement, una de les mostres de teatre de carrer més nostrades i menys estudiades de la València Moderna. En aquest article es realitza una revisió bibliogràfica crítica i una primera anàlisi historiogràfica.Paraules clau: Ball de Torrent, Dansa i música tradicional, Teatre, Moixiganga, Festa valencianaAbstract: Ball de Torrent (Dance of Torrent is a popular dramatic masquerade staged in Valencia since the late seventeenth century to the early twentieth. It was organized by guilds, hospital managements or festival organizers. The actors were grouped in associations representing a parody on the relationships between power structures and popular classes. Despite the variability depending on the historical period, it consisted of a mixture of episodes or scenes with dance, music and theatre games. Any Festivals in Valencia are connected with the Ball de Torrent. It’s probably one of the most interesting samples of street theatre and studied under of the Modern Valencia. This paper analyses historical sources to review and critique bibliography.Keywords: Dance of Torrent, Traditional Dance and Music, Theatre, Masquerade, Feasts of Valencia

  17. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    Science.gov (United States)

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research.

  18. Characterization of Ball Milled Al-Al2O3 sub-micron Composites

    Science.gov (United States)

    Dagasan, E.; Gercekcioglu, E.; Unalan, S.

    2018-01-01

    The purpose of this study is to investigate properties of the composite powders produced by ball milling process. Different weight ratio of high purity Al2O3 powders were added to the Al matrix as reinforcing element. Ball milling process was conducted by a planetary type ball mill with WC milling balls and vial at constant parameters like rotating speed, time, Ball-to-Powder ratio and Process Control Agent. Samples that taken from the powder mixtureby various time intervals were analyzed by SEM, XRD and BET surface area and porosity measurement systems.

  19. Analysis on Sealing Reliability of Bolted Joint Ball Head Component of Satellite Propulsion System

    Science.gov (United States)

    Guo, Tao; Fan, Yougao; Gao, Feng; Gu, Shixin; Wang, Wei

    2018-01-01

    Propulsion system is one of the important subsystems of satellite, and its performance directly affects the service life, attitude control and reliability of the satellite. The Paper analyzes the sealing principle of bolted joint ball head component of satellite propulsion system and discuss from the compatibility of hydrazine anhydrous and bolted joint ball head component, influence of ground environment on the sealing performance of bolted joint ball heads, and material failure caused by environment, showing that the sealing reliability of bolted joint ball head component is good and the influence of above three aspects on sealing of bolted joint ball head component can be ignored.

  20. Acoustic evaluation of concrete delaminations using ball-chain impact excitation.

    Science.gov (United States)

    Sun, Hongbin; Zhu, Jinying; Ham, Suyun

    2017-05-01

    This letter presents an automated acoustic sensing device for rapid detection of delamination in concrete. The device consists of ball-chains for continual impact excitation and multi-channel microphones for acoustic sensing. A ball-chain is formed by multiple metal balls connected by flexible ropes and is dragged on concrete surface to excite vibration of delaminations. Compared to the conventional chain drag test, the ball-chain generates acoustic signals with higher signal-to-noise ratio (S/N) because the balls give isolated but continual impacts on concrete surface during dragging. The proposed method was validated on a concrete specimen with artificial delaminations.