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Sample records for resistance jumps ranging

  1. ECCENTRIC AND CONCENTRIC JUMPING PERFORMANCE DURING AUGMENTED JUMPS WITH ELASTIC RESISTANCE: A META-ANALYSIS.

    Science.gov (United States)

    Aboodarda, Saied Jalal; Page, Phillip A; Behm, David George

    2015-11-01

    The initial rapid eccentric contraction of a stretch-shortening cycle (SSC) activity is typically reported to accentuate the subsequent concentric jump performance. Some researchers have rationalized that adding elastic resistance (ER) to explosive type activities (e.g. countermovement jumps and drop jumps) would increase excitatory stretch reflex activity and mechanical recoil characteristics of the musculotendinous tissues. The purpose of this meta-analysis was to examine the available literature on jumping movements augmented with ER and to provide a quantitative summary on the effectiveness of this technique for enhancing acute eccentric and concentric jumping performance. In a random-effects model, the Hedges`s g effect size (ES) was used to calculate the biased corrected standardized mean difference between the augmented and similar non-augmented jumps. The results demonstrated that augmented jumps provided a greater eccentric loading compared to free jumps (Hedges`s g ES = 0.237, p = 0.028). However the concentric performance was significantly impaired, particularly if the downward elastic force was used during concentric phase as well (ES = -2.440, p recoil properties. These results suggest that the release of elastic force at the beginning of the concentric phase seems to be a critical point to avoid impairment of acute concentric performance in augmented jumps. 2a.

  2. Aerodynamic Jump: A Short Range View for Long Rod Projectiles

    Directory of Open Access Journals (Sweden)

    Mark Bundy

    2001-01-01

    Full Text Available It is shown that aerodynamic jump for a nonspinning kinetic energy penetrator is not – as conventional definitions may infer – a discontinuous change in the direction of motion at the origin of free flight, nor is it the converse, a cumulative redirection over a domain of infinite extent. Rather, with the aid of an alternative kinematical definition, it is shown that aerodynamic jump for such a projectile is a localized redirection of the center-of-gravity motion, caused by the force of lift due to yaw over the relatively short region from entry into free flight until the yaw reaches its first maximum. A rigorous proof of this statement is provided, but the primary objective of this paper is to provide answers to the questions: what is aerodynamic jump, what does it mean, and what aspects of the flight trajectory does it refer to, or account for.

  3. ACUTE EFFECTS OF A RESISTED DYNAMIC WARM-UP PROTOCOL ON JUMPING PERFORMANCE

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    Cilli, M; Yildiz, S; Saglam, T; Camur, MH

    2014-01-01

    This study aimed to investigate the kinematic and kinetic changes when resistance is applied in horizontal and vertical directions, produced by using different percentages of body weight, caused by jumping movements during a dynamic warm-up. The group of subjects consisted of 35 voluntary male athletes (19 basketball and 16 volleyball players; age: 23.4 ± 1.4 years, training experience: 9.6 ± 2.7 years; height: 177.2 ± 5.7 cm, body weight: 69.9 ± 6.9 kg) studying Physical Education, who had a jump training background and who were training for 2 hours, on 4 days in a week. A dynamic warm-up protocol containing seven specific resistance movements with specific resistance corresponding to different percentages of body weight (2%, 4%, 6%, 8%, 10%) was applied randomly on non consecutive days. Effects of different warm-up protocols were assessed by pre-/post- exercise changes in jump height in the countermovement jump (CMJ) and the squat jump (SJ) measured using a force platform and changes in hip and knee joint angles at the end of the eccentric phase measured using a video camera. A significant increase in jump height was observed in the dynamic resistance warm-up conducted with different percentages of body weight (p 0.05). In jump movements before and after the warm-up, while no significant difference between the vertical ground reaction forces applied by athletes was observed (p > 0.05), in some cases of resistance, a significant reduction was observed in hip and knee joint angles (p jumping movements, as well as an increase in jump height values. As a result, dynamic warm-up exercises could be applicable in cases of resistance corresponding to 6-10% of body weight applied in horizontal and vertical directions in order to increase the jump performance acutely. PMID:25435670

  4. Optimal loading range for the development of peak power output in the hexagonal barbell jump squat.

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    Turner, Thomas S; Tobin, Daniel P; Delahunt, Eamonn

    2015-06-01

    Recent studies indicate that the utilization of the hexagonal barbell jump squat (HBJS) compared with the traditional barbell jump squat may offer a superior method of developing peak power. The notion that a single optimal load may be prescribed in training programs aiming to develop peak power is subject to debate. The purpose of this study was to identify the optimal load corresponding with peak power output during the HBJS in professional rugby union players. Seventeen professional rugby union players participated in this study. Participants performed 3 unloaded countermovement jumps on a force plate and 3 HBJS at each of the following randomized loads: 10, 20, 30, and 40% of box squat 1 repetition maximum (1RM). Peak power output was the dependent variable of interest. A one-way repeated measures analysis of variance was conducted to compare peak power output across each load. Peak power output was the dependent variable of interest. A significant main effect for load was observed (Wilk's Lambda = 0.11, F(4,13) = 18.07, p < 0.01, partial η2 = 0.88). Results of the Bonferroni-adjusted pairwise comparisons indicated that peak power output in the HBJS is optimized at a load range between 10 and 20% of box squat 1RM. The results of this study indicate that the use of the HBJS with a training load between 10 and 20% of box squat 1RM optimizes peak power output in professional rugby union players.

  5. Effects of resistance training on jumping performance in pre-adolescent rhythmic gymnasts: a randomized controlled study.

    Science.gov (United States)

    Piazza, Marina; Battaglia, Claudia; Fiorilli, Giovanni; Innocenti, Giovanni; Iuliano, Enzo; Aquino, Giovanna; Calcagno, Giuseppe; Giombini, Arrigo; Di Cagno, Alessandra

    2014-01-01

    The aim of this study was to determine the effectiveness of two different resistance training programs on lower limb explosive and reactive strength in young female athletes. Fifty seven rhythmic gymnasts were randomly assigned to unspecific resistance training with dumbbells (12 repetition maximum squats) (n = 19; age = 12.0 +/- 1.8 years) or to specific resistance training with weighted belts (6% of body mass; n = 18; age = 11.9 +/- 1.0 years). Squat jump test, counter movement jump test, hopping test, flexibility of the hip, and anthropometric measures were assessed before and after six weeks training. The main result was that both unspecific resistance training and specific resistance training protocols positively affected the jumping performance, with an increase of the lower limb explosive strength of 6-7%, with no side effects. Counter movement jump flight time increased significantly (p rhythmic gymnastics training enhance jumping ability in young female athletes.

  6. Shifts in diversification rates and host jump frequencies shaped the diversity of host range among Sclerotiniaceae fungal plant pathogens

    OpenAIRE

    Taylor, Andrew; Clarkson, John; Raffaele, Sylvain; Navaud, Olivier; Barbacci, Adelin

    2017-01-01

    The range of hosts that a parasite can infect in nature is a trait determined by its own evolutionary history and that of its potential hosts. However, knowledge on host range diversity and evolution at the family level is often lacking. Here, we investigate host range variation and diversification trends within the Sclerotiniaceae , a family of Ascomycete fungi. Using a phylogenetic framework, we associate diversification rates, the frequency of host jump events, and host range variation dur...

  7. Shifts in diversification rates and host jump frequencies shaped the diversity of host range among Sclerotiniaceae fungal plant pathogens.

    Science.gov (United States)

    Navaud, Olivier; Barbacci, Adelin; Taylor, Andrew; Clarkson, John P; Raffaele, Sylvain

    2018-03-01

    The range of hosts that a parasite can infect in nature is a trait determined by its own evolutionary history and that of its potential hosts. However, knowledge on host range diversity and evolution at the family level is often lacking. Here, we investigate host range variation and diversification trends within the Sclerotiniaceae, a family of Ascomycete fungi. Using a phylogenetic framework, we associate diversification rates, the frequency of host jump events and host range variation during the evolution of this family. Variations in diversification rate during the evolution of the Sclerotiniaceae define three major macro-evolutionary regimes with contrasted proportions of species infecting a broad range of hosts. Host-parasite cophylogenetic analyses pointed towards parasite radiation on distant hosts long after host speciation (host jump or duplication events) as the dominant mode of association with plants in the Sclerotiniaceae. The intermediate macro-evolutionary regime showed a low diversification rate, high frequency of duplication events and the highest proportion of broad host range species. Our findings suggest that the emergence of broad host range fungal pathogens results largely from host jumps, as previously reported for oomycete parasites, probably combined with low speciation rates. These results have important implications for our understanding of fungal parasites evolution and are of particular relevance for the durable management of disease epidemics. © 2018 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  8. Comparison 2 methods of resistance training (conventional and bodypump) on the agility and vertical jump in male basketball players 16-18 years

    OpenAIRE

    SALIMI, Hamid; BARATI, Amir; ADIBPOUR, Nahid

    2015-01-01

    The aim of this study was to compare an bodypump and resistance training on agility and vertical jump on male basketball players 16-18years. Therefore 36 teenage basketball players voluntarily chosen and randomly divided into three groups including: bodypump group (n=12,age 17 ± 0.5 year, height 179 ± 0.05 cm and a weight 69.26± 12.22 kg) and resistance group (n=12, age rangen 17± 0.6 years, range height 178 ± 0.09 cm and weight 68.55 ± 14.25 kg) and control group (n=12, age 17 ± 0.5 years, h...

  9. The effect of whole-body vibration on jump height and active range of movement in female dancers.

    Science.gov (United States)

    Marshall, Lucille C; Wyon, Matthew A

    2012-03-01

    Whole-body vibration (WBV) has been shown to have beneficial effects on strength and power indices in sedentary and moderately trained individuals. The aim of this study was to investigate the effect of 4 weeks of WBV on jump height, active range of motion (AROM), and leg anthropometry in conservatoire dance students. Seventeen female dancers were randomly assigned to a control or intervention group. The intervention group trained for 30 seconds per position at a 35-Hz frequency, 8-mm displacement in the first 2 weeks, and 40 seconds at 40 Hz for the final 2 weeks, whereas the control group carried out the same exercises but without vibration stimulation. A significant (p < 0.01) difference in the intervention group was noted over time for vertical jump and active ROM. No significant changes over time were noted in the anthropometric data. In conclusion, WBV can be used as a beneficial supplemental training intervention to increase jump and active flexibility in highly trained dancers without corresponding increases in relative anthropometric data.

  10. Effects of weightlifting exercise, traditional resistance and plyometric training on countermovement jump performance: a meta-analysis.

    Science.gov (United States)

    Berton, Ricardo; Lixandrão, Manoel E; Pinto E Silva, Claudio M; Tricoli, Valmor

    2018-02-01

    Jump performance is considered an important factor in many sports. Thus, strategies such as weightlifting (WL) exercises, traditional resistance training (TRT) and plyometric training (PT) are effective at improving jump performance. However, it is not entirely clear which of these strategies can enable greater improvements on jump height. Thus, the purpose of the meta-analysis was to compare the improvements on countermovement jump (CMJ) performance between training methods which focus on WL exercises, TRT, and PT. Seven studies were included, of which one study performed both comparison. Therefore, four studies comparing WL exercises vs. TRT (total n = 78) and four studies comparing WL exercises vs. PT (total n = 76). The results showed greater improvements on CMJ performance for WL exercises compared to TRT (ES diff : 0.72 ± 0.23; 95% CI: 0.26, 1.19; P = 0.002; Δ % = 7.5 and 2.1, respectively). The comparison between WL exercises vs. PT revealed no significant difference between protocols (ES diff : 0.15 ± 0.23; 95% CI: -0.30, 0.60; P = 0.518; Δ % = 8.8 and 8.1, respectively). In conclusion, WL exercises are superior to promote positive changes on CMJ performance compared to TRT; however, WL exercises and PT are equally effective at improving CMJ performance.

  11. Addition of Glute-Ham-Gastroc Raise to a Resistance Training Program: Effect on Jump Propulsion and Landing.

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    Chiu, Loren Z F; Yaremko, Anita; vonGaza, Gabriella L

    2017-09-01

    Chiu LZF, Yaremko A, and vonGaza GL. Addition of glute-ham-gastroc raise to a resistance training program: effect on jump propulsion and landing. J Strength Cond Res 31(9): 2562-2571, 2017-Exercises such as squats and cleans are commonly used in resistance training programs to enhance athletic performance. However, these exercises may not effectively train the gastrocnemius, an important muscle for energy generation and absorption. The purpose of this research was to examine the effects of adding glute-ham-gastroc raise exercise to target the gastrocnemius to a traditional resistance training program involving squats and cleans. Vertical jump height, weight-bearing ankle dorsiflexion, and jump propulsion and landing mechanics were examined before and after an 8-week training intervention in female youth volleyball players. Approach (with: [INCREMENT] = 2.6 ± 1.7 cm; 90% confidence interval [CI] [1.8-3.6 cm] vs. without: [INCREMENT] = 1.8 ± 1.9 cm; 90% CI [0.8-2.8 cm]) and standing (with: [INCREMENT] = 2.7 ± 1.7 cm; 90% CI [1.7-3.6 cm] vs. without: [INCREMENT] = 1.6 ± 1.5 cm; 90% CI [0.8-2.4 cm]) vertical jump height increased more in the group performing glute-ham-gastroc raise. Weight-bearing ankle dorsiflexion increased when glute-ham-gastroc raise was included (left: [INCREMENT] = 4.1 ± 4.1°; 90% CI [1.9-6.4°] and right: [INCREMENT] = 4.1 ± 3.9°; 90% CI [1.9-6.2°]) but did not appear to change with resistance training only (left: [INCREMENT] = 1.4 ± 4.5°; 90% CI [-1.0 to 3.9°] and right: [INCREMENT] = 2.5 ± 4.4°; [-0.3 to 4.5°]). No discernible differences were observed for changes in jump propulsion and landing mechanics between groups. Glute-ham-gastroc raise may have a beneficial effect with young athletes when added to squat- and clean-based resistance training programs.

  12. The effects of resistance training interventions on vertical jump performance in basketball players: a meta-analysis.

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    Sperlich, Paula F; Behringer, Michael; Mester, Joachim

    2016-01-01

    Vertical jump performance is one of the key factors in basketball. In order to determine the effectiveness of previously published interventions and their influencing factors we performed a meta-analysis. A computerized search was conducted using the databases PubMed (1966), Web of Science (1900), SPORTDiscus™ (1975),Medline (1966) and SportPilot (2008). Studies involving healthy male or female basketball players at any age and performance level were included. All trials had to investigate the benefits of resistance training programs on jumping performance in basketball players and provide a control group. The effect size (ES) was computed and the relationship between ESs and continuous variables was examined by meta-regressions, whereas subgroup meta-analyses and z-tests were used to assess the impact of categorical moderator variables. The meta-analysis included 14 studies with 20 subgroups and a total of 37 outcomes. A total of 399 participants were examined, N.=157 served as control and N.=242 took part in particular training interventions. The overall weighted ES of 0.78 (95% CI 0.41, 1.15) was significantly greater than zero (Ptraining effect. However, positive correlations were found for training duration (r=0.68; P=0.02). The present meta-analysis demonstrates that resistance training throughout the year, using bodyweight or external weight, significantly improves vertical jump performance in healthy basketball players. Since vertical jump improvements were independent of intervention period but dependent on the duration of each individual training session the total training amount should be based on longer training sessions.

  13. Effect of Resistance Tube Exercises on Kicking Accuracy, Vertical Jump and 40-Yard Technical Test in Competitive Football Players – An Experimental Study

    Directory of Open Access Journals (Sweden)

    Tirumala Alekhya

    2014-09-01

    Full Text Available Purpose. Kicking, jumping and agility are important skills in football. These activities require adequate lower limb strength, which can be enhanced with resistance training. The objective of the study was to evaluate the effect of resistance tube exercises on kicking accuracy, vertical jump performance and 40-yard technical test results in competitive football players. Methods. The study involved 23 competitive football players (11 males, 12 females aged from 18-20 years recruited from three different universities in Belgaum, Karnataka, India. Back heel kick accuracy, vertical jump height and 40-yard technical test time were evaluated before and after a 2-week resistance tube exercise program. Results. Significant improvements in post-intervention kicking accuracy were found when males and females were treated as a single group (p = 0.01. Vertical jump height also showed a highly significant post-intervention improvement in the males and for the combined group of males and females (p = 0.001. The 40-yard technical test values significantly improved in the females and in the combined results for males and females (p = 0.001. Conclusions. The two-week resistance tube exercise program was found to have an effect on kicking accuracy, vertical jump height and 40-yard technical test performance in competitive football players. Resistance tube exercises can thus be included as a component of a regular strength training program for such athletes.

  14. Pressure Jumps during Drainage in Macroporous Soils

    DEFF Research Database (Denmark)

    Soto, Diego; Paradelo Pérez, Marcos; Corral, A

    2018-01-01

    Tensiometer readings obtained at high resolution during drainage of structured soil columns revealed pressure jumps with long range correlations and burst sequences with a hierarchical structure. The statistical properties of jumps are similar to Haines jumps described in invasion percolation...

  15. Effectiveness of resistance training or jumping-exercise to increase bone mineral density in men with low bone mass: a 12-month randomized, clinical trial

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    Hinton, Pamela S.; Nigh, Peggy; Thyfault, John

    2015-01-01

    Purpose To examine the effects of 12 mo of resistance training (RT, 2x/wk, N= 19) or jump training (JUMP, 3x/wk, N= 19) on bone mineral density (BMD) and bone turnover markers (BTM) in physically active (≥4 hr/wk) men (mean age: 44 ± 2 y; median: 44 y) with osteopenia of the hip or spine. Methods Participants rated pain and fatigue following each RT or JUMP session. All participants received supplemental calcium (1200 mg/d) and vitamin D (10 μg/d). BMD was measured at 0, 6, and 12 mo using DXA scans of the whole body (WB), total hip (TH) and lumbar spine (LS). BTM and 25 OHD were measured by ELISA. The effects of RT or JUMP on BMD and BTM were evaluated using 3×2 repeated measures ANOVA (time, group). This study was conducted in accordance with the Declaration of Helsinki and was approved by the University of Missouri IRB. Results At baseline, 36 of 38 participants were vitamin D sufficient (25OHD>50 nmol/L); at 12 mo, all participants were 25OHD sufficient. 25OHD did not differ between groups. WB and LS BMD significantly increased after 6 months of RT or JUMP and this increase was maintained at 12 mo; TH BMD increased only in RT. Osteocalcin increased significantly after 12 mo of RT or JUMP; CTx decreased significantly after 6 mo and returned to baseline concentrations at 12 mo in both RT and JUMP. Pain and fatigue ratings after RT or JUMP sessions were very low at 0, 6, and 12 mo. Conclusion RT or JUMP, which appeared safe and feasible, increased BMD of the whole body and lumbar spine, while RT also increased hip BMD, in moderately active, osteopenic men. PMID:26092649

  16. Effects of Heavy Squat Training on a Vibration Platform on Maximal Strength and Jump Performance in Resistance-Trained Men.

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    Hammer, Roger L; Linton, Joshua T; Hammer, Adam M

    2018-03-06

    The purpose of this investigation was to determine maximal strength and jump performance outcomes of heavy squat training on a low-amplitude (<1.0 mm peak-to-peak) vibration platform (VP). Nineteen recreationally resistance-trained college-aged men (22.3 ± 1.66 years) completed the 6-week study. Participants were randomly assigned to one of two training groups: SQT (n = 10) performed conventional back squats on the floor; SQTV (n = 9) performed back squats on the VP. Supervised training took place over 12 sessions (2 days/week) which utilized an aggressive strength development protocol (85-95 % 1-RM), which was identically followed by both groups. After the intervention, both groups showed (via t-test) a marked increase (p < 0.001) in 1-RM squat strength (SQT = 34.5 kg vs SQTV = 36.2 kg), but there was no significant difference (via mixed ANOVA) between groups (p = 0.875). Standing broad jump performance increased by an average of 5-6 cm, but was not significantly changed in either group (SQT; p = 0.199, SQTV; p = 0.087). In conclusion, squats performed with whole body vibration (WBV) were not superior to conventional squats with respect to maximal strength and jump performance outcomes. It appears that there was no additive effect of superimposed WBV training in strength beyond that caused by strength training alone. This study can help strength conditioning professionals and athletes make an informed decision on whether to invest in a VP and use WBV as an alternative or a complementary mode of training.

  17. The effect of sprinting after each set of heavy resistance training on the running speed and jumping performance of young basketball players.

    Science.gov (United States)

    Tsimahidis, Konstantinos; Galazoulas, Christos; Skoufas, Dimitrios; Papaiakovou, Georgios; Bassa, Eleni; Patikas, Dimitrios; Kotzamanidis, Christos

    2010-08-01

    The purpose of this study was to investigate the effect of a 10-week heavy resistance combined with a running training program on the strength, running speed (RS), and vertical jump performance of young basketball players. Twenty-six junior basketball players were equally divided in 2 groups. The control (CON) group performed only technical preparation and the group that followed the combined training program (CTP) performed additionally 5 sets of 8-5 repetition maximum (RM) half squat with 1 30-m sprint after each set. The evaluation took place before training and after the 5th and 10th weeks of training. Apart from the 1RM half squat test, the 10- and 30-m running time was measured using photocells and the jump height (squat, countermovement jump, and drop jump) was estimated taking into account the flight time. The 1RM increased by 30.3 +/- 1.5% at the 10th week of training for the CTP group (p 0.05). In general, all measured parameters showed a statistically significant increase after the 5th and 10th weeks (p 0.05). This suggests that the applied CTP is beneficial for the strength, RS, and jump height of young basketball players. The observed adaptations in the CTP group could be attributed to learning factors and to a more optimal transfer of the strength gain to running and jumping performance.

  18. Changes in Sprint and Jump Performances After Traditional, Plyometric, and Combined Resistance Training in Male Youth Pre- and Post-Peak Height Velocity.

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    Lloyd, Rhodri S; Radnor, John M; De Ste Croix, Mark B A; Cronin, John B; Oliver, Jon L

    2016-05-01

    The purpose of this study was to compare the effectiveness of 6-week training interventions using different modes of resistance (traditional strength, plyometric, and combined training) on sprinting and jumping performances in boys before and after peak height velocity (PHV). Eighty school-aged boys were categorized into 2 maturity groups (pre- or post-PHV) and then randomly assigned to (a) plyometric training, (b) traditional strength training, (c) combined training, or (d) a control group. Experimental groups participated in twice-weekly training programs for 6 weeks. Acceleration, maximal running velocity, squat jump height, and reactive strength index data were collected pre- and postintervention. All training groups made significant gains in measures of sprinting and jumping irrespective of the mode of resistance training and maturity. Plyometric training elicited the greatest gains across all performance variables in pre-PHV children, whereas combined training was the most effective in eliciting change in all performance variables for the post-PHV cohort. Statistical analysis indicated that plyometric training produced greater changes in squat jump and acceleration performances in the pre-PHV group compared with the post-PHV cohort. All other training responses between pre- and post-PHV cohorts were not significant and not clinically meaningful. The study indicates that plyometric training might be more effective in eliciting short-term gains in jumping and sprinting in boys who are pre-PHV, whereas those who are post-PHV may benefit from the additive stimulus of combined training.

  19. The effects of a combined resisted jump training and rugby-conditioning program on selected physical, motor ability and anthropometric components of rugby players / Jacobus Johannes Oosthuizen

    OpenAIRE

    Oosthuizen, Jacobus Johannes

    2013-01-01

    Plyometrics is primarily used by coaches and sport scientists to improve explosive power among athletes who participate in dynamic, high intensity type of sports. One of the plyometric-related training methods that has received attention in recent years, is loaded or resistance (resistive) jump training. Limited research does, however, exist with regard to the benefits and use of this training method as well as in conjunction with other training methods, especially among team spor...

  20. Changes in muscle cross-sectional area, muscle force, and jump performance during 6 weeks of progressive whole-body vibration combined with progressive, high intensity resistance training.

    Science.gov (United States)

    Rosenberger, A; Beijer, Å; Johannes, B; Schoenau, E; Mester, J; Rittweger, J; Zange, J

    2017-06-01

    We hypothesized that progressive whole-body vibration (WBV) superimposed to progressive high intensity resistance training has greater effects on muscle cross-sectional area (CSA), muscle force of leg muscles, and jump performance than progressive high intensity resistance training alone. Two groups of healthy male subjects performed either 6 weeks of Resistive Vibration Exercise (RVE, squats and heel raises with WBV, n=13) or Resistive Exercise (RE, squats and heel raises without WBV, n=13). Squats under RVE required indispensable weight loading on the forefoot to damp harmful vibrations to the head. Time, intervention, and interaction effects were analyzed. After 6 weeks of training, knee extensor CSA, isometric knee extension force, and counter movement jump height increased equally in both groups (time effect, P⟨0.001, P≤0.02, and P≤0.03, respectively), whereas only in RVE ankle plantar flexor CSA and isometric ankle plantar flexion force reached significance or a tendency, respectively, (time effect, P=0.015 and P=0.069, respectively; intervention effect also for the latter, P=0.006). Drop jump contact time did significantly more improve in RVE (interaction effect, P=0.042). RVE showed better training effects than RE only in plantar flexor muscles. RVE seems to be suitable in professional sports with a special focus on calf muscles.

  1. Jumping Dynamics

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2013-01-01

    We propose an alternative paradigm to the conjectured Miransky scaling potentially underlying the physics describing the transition from the conformally broken to the conformally restored phase when tuning certain parameters such as the number of flavors in gauge theories. According to the new pa...... without particle interpretation. The jumping scenario, therefore, does not support a near-conformal dynamics of walking type. We will also discuss the impact of jumping dynamics on the construction of models of dynamical electroweak symmetry breaking....

  2. Enhanced Jumping-Droplet Departure.

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    Kim, Moon-Kyung; Cha, Hyeongyun; Birbarah, Patrick; Chavan, Shreyas; Zhong, Chen; Xu, Yuehan; Miljkovic, Nenad

    2015-12-15

    Water vapor condensation on superhydrophobic surfaces has received much attention in recent years because of its ability to shed water droplets at length scales 3 decades smaller than the capillary length (∼1 mm) via coalescence-induced droplet jumping. Jumping-droplet condensation has been demonstrated to enhance heat transfer, anti-icing, and self-cleaning efficiency and is governed by the theoretical inertial-capillary scaled jumping speed (U). When two droplets coalesce, the experimentally measured jumping speed (Uexp) is fundamentally limited by the internal fluid dynamics during the coalescence process (Uexp 2) coalescence as an avenue to break the two-droplet speed limit. Using side-view and top-view high-speed imaging to study more than 1000 jumping events on a copper oxide nanostructured superhydrophobic surface, we verify that droplet jumping occurs as a result of three fundamentally different mechanisms: (1) coalescence between two droplets, (2) coalescence among more than two droplets (multidroplet), and (3) coalescence between one or more droplets on the surface and a returning droplet that has already departed (multihop). We measured droplet-jumping speeds for a wide range of droplet radii (5-50 μm) and demonstrated that while the two-droplet capillary-to-inertial energy conversion mechanism is not identical to that of multidroplet jumping, speeds above the theoretical two-droplet limit (>0.23U) can be achieved. However, we discovered that multihop coalescence resulted in drastically reduced jumping speeds (≪0.23U) due to adverse momentum contributions from returning droplets. To quantify the impact of enhanced jumping speed on heat-transfer performance, we developed a condensation critical heat flux model to show that modest jumping speed enhancements of 50% using multidroplet jumping can enhance performance by up to 40%. Our results provide a starting point for the design of enhanced-performance jumping-droplet surfaces for industrial

  3. An examination of training on the VertiMax resisted jumping device for improvements in lower body power in highly trained college athletes .

    Science.gov (United States)

    Rhea, Matthew R; Peterson, Mark D; Oliverson, Jeff R; Ayllón, Fernando Naclerio; Potenziano, Ben J

    2008-05-01

    Training to develop superior muscular power has become a key component to most progressive sport conditioning programs. Conventional resistance training, plyometrics, and speed/agility modalities have all been employed in an effort to realize superlative combinations of training stimuli. New training devices such as the VertiMax resisted jump trainer are marketed as a means of improving lower body reactive power. The purpose of this study was to evaluate the effectiveness of the VertiMax, in combination with traditional training modalities, for improvements in lower body power among highly trained athletes. Forty men and women Division I collegiate athletes representing the sports of baseball, basketball, soccer, gymnastics, and track completed a 12-week mixed-methods training program. Two groups were constructed with both groups performing the same conventional resistance training and strength training exercises. The training control group performed traditional plyometric exercises while the experimental group performed similar loaded jump training on the VertiMax. Lower body power was measured before and after the training program by the TENDO FiTROdyne Powerlizer and statistically compared for differences between groups. Data analyses identified a significant (p training alone (effect size = 0.09). These data convincingly demonstrate that the VertiMax represents an effective strategy for developing lower body power among trained college athletes, when combined with traditional strength and conditioning approaches.

  4. Coordination in vertical jumping

    NARCIS (Netherlands)

    Bobbert, Maarten F.; van Ingen Schenau, Gerrit Jan

    1988-01-01

    The present study was designed to investigate for vertical jumping the relationships between muscle actions, movement pattern and jumping achievement. Ten skilled jumpers performed jumps with preparatory countermovement. Ground reaction forces and cinematographic data were recorded. In addition,

  5. Conditioning exercises in ski jumping: biomechanical relationship of squat jumps, imitation jumps, and hill jumps.

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    Lorenzetti, Silvio; Ammann, Fabian; Windmüller, Sabrina; Häberle, Ramona; Müller, Sören; Gross, Micah; Plüss, Michael; Plüss, Stefan; Schödler, Berni; Hübner, Klaus

    2017-11-22

    As hill jumps are very time-consuming, ski jumping athletes often perform various imitation jumps during training. The performed jumps should be similar to hill jumps, but a direct comparison of the kinetic and kinematic parameters has not been performed yet. Therefore, this study aimed to correlate 11 common parameters during hill jumps (Oberstdorf Germany), squat jumps (wearing indoor shoes), and various imitation jumps (rolling 4°, rolling flat, static; jumping equipment or indoor shoes) on a custom-built instrumented vehicle with a catch by the coach. During the performed jumps, force and video data of the take-off of 10 athletes were measured. The imitation and squat jumps were then ranked. The main difference between the hill jumps and the imitation and squat jumps is the higher maximal force loading rate during the hill jumps. Imitation jumps performed on a rolling platform, on flat ground were the most similar to hill jumps in terms of the force-time, and leg joint kinematic properties. Thus, non-hill jumps with a technical focus should be performed from a rolling platform with a flat inrun with normal indoor shoes or jumping equipment, and high normal force loading rates should be the main focus of imitation training.

  6. Optimal Ski Jump

    Science.gov (United States)

    Rebilas, Krzysztof

    2013-02-01

    Consider a skier who goes down a takeoff ramp, attains a speed V, and jumps, attempting to land as far as possible down the hill below (Fig. 1). At the moment of takeoff the angle between the skier's velocity and the horizontal is α. What is the optimal angle α that makes the jump the longest possible for the fixed magnitude of the velocity V? Of course, in practice, this is a very sophisticated problem; the skier's range depends on a variety of complex factors in addition to V and α. However, if we ignore these and assume the jumper is in free fall between the takeoff ramp and the landing point below, the problem becomes an exercise in kinematics that is suitable for introductory-level students. The solution is presented here.

  7. Risk, Jumps, and Diversification

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Law, Tzuo Hann; Tauchen, George

    We test for price discontinuities, or jumps, in a panel of high-frequency intraday returns for forty large-cap stocks and an equiweighted index from these same stocks. Jumps are naturally classified into two types: common and idiosyncratic. Common jumps affect all stocks, albeit to varying degrees......, while idiosyncratic jumps are stock-specific. Despite the fact that each of the stocks has a of about unity with respect to the index, common jumps are virtually never detected in the individual stocks. This is truly puzzling, as an index can jump only if one or more of its components jump. To resolve...

  8. Effects of Resisted Sprint Training and Traditional Power Training on Sprint, Jump, and Balance Performance in Healthy Young Adults: A Randomized Controlled Trial

    Science.gov (United States)

    Prieske, Olaf; Krüger, Tom; Aehle, Markus; Bauer, Erik; Granacher, Urs

    2018-01-01

    Power training programs have proved to be effective in improving components of physical fitness such as speed. According to the concept of training specificity, it was postulated that exercises must attempt to closely mimic the demands of the respective activity. When transferring this idea to speed development, the purpose of the present study was to examine the effects of resisted sprint (RST) vs. traditional power training (TPT) on physical fitness in healthy young adults. Thirty-five healthy, physically active adults were randomly assigned to a RST (n = 10, 23 ± 3 years), a TPT (n = 9, 23 ± 3 years), or a passive control group (n = 16, 23 ± 2 years). RST and TPT exercised for 6 weeks with three training sessions/week each lasting 45–60 min. RST comprised frontal and lateral sprint exercises using an expander system with increasing levels of resistance that was attached to a treadmill (h/p/cosmos). TPT included ballistic strength training at 40% of the one-repetition-maximum for the lower limbs (e.g., leg press, knee extensions). Before and after training, sprint (20-m sprint), change-of-direction speed (T-agility test), jump (drop, countermovement jump), and balance performances (Y balance test) were assessed. ANCOVA statistics revealed large main effects of group for 20-m sprint velocity and ground contact time (0.81 ≤ d ≤ 1.00). Post-hoc tests showed higher sprint velocity following RST and TPT (0.69 ≤ d ≤ 0.82) when compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to 4.5% for RST [90%CI: (−1.1%;10.1%), d = 1.23] and 2.6% for TPT [90%CI: (0.4%;4.8%), d = 1.59]. Additionally, ground contact times during sprinting were shorter following RST and TPT (0.68 ≤ d ≤ 1.09) compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to −6.3% for RST [90%CI: (−11.4%;−1.1%), d = 1.45) and −2.7% for TPT [90%CI: (−4.2%;−1.2%), d = 2.36]. Finally, effects

  9. Effects of Resisted Sprint Training and Traditional Power Training on Sprint, Jump, and Balance Performance in Healthy Young Adults: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Olaf Prieske

    2018-03-01

    Full Text Available Power training programs have proved to be effective in improving components of physical fitness such as speed. According to the concept of training specificity, it was postulated that exercises must attempt to closely mimic the demands of the respective activity. When transferring this idea to speed development, the purpose of the present study was to examine the effects of resisted sprint (RST vs. traditional power training (TPT on physical fitness in healthy young adults. Thirty-five healthy, physically active adults were randomly assigned to a RST (n = 10, 23 ± 3 years, a TPT (n = 9, 23 ± 3 years, or a passive control group (n = 16, 23 ± 2 years. RST and TPT exercised for 6 weeks with three training sessions/week each lasting 45–60 min. RST comprised frontal and lateral sprint exercises using an expander system with increasing levels of resistance that was attached to a treadmill (h/p/cosmos. TPT included ballistic strength training at 40% of the one-repetition-maximum for the lower limbs (e.g., leg press, knee extensions. Before and after training, sprint (20-m sprint, change-of-direction speed (T-agility test, jump (drop, countermovement jump, and balance performances (Y balance test were assessed. ANCOVA statistics revealed large main effects of group for 20-m sprint velocity and ground contact time (0.81 ≤ d ≤ 1.00. Post-hoc tests showed higher sprint velocity following RST and TPT (0.69 ≤ d ≤ 0.82 when compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to 4.5% for RST [90%CI: (−1.1%;10.1%, d = 1.23] and 2.6% for TPT [90%CI: (0.4%;4.8%, d = 1.59]. Additionally, ground contact times during sprinting were shorter following RST and TPT (0.68 ≤ d ≤ 1.09 compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to −6.3% for RST [90%CI: (−11.4%;−1.1%, d = 1.45 and −2.7% for TPT [90%CI: (−4.2%;−1.2%, d = 2.36]. Finally, effects

  10. Drought resistant fodder crops | GC | African Journal of Range and ...

    African Journals Online (AJOL)

    African Journal of Range and Forage Science. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 2, No 1 (1967) >. Log in or Register to get access to full text downloads.

  11. Performance analysis of jump-gliding locomotion for miniature robotics.

    Science.gov (United States)

    Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M

    2015-03-26

    Recent work suggests that jumping locomotion in combination with a gliding phase can be used as an effective mobility principle in robotics. Compared to pure jumping without a gliding phase, the potential benefits of hybrid jump-gliding locomotion includes the ability to extend the distance travelled and reduce the potentially damaging impact forces upon landing. This publication evaluates the performance of jump-gliding locomotion and provides models for the analysis of the relevant dynamics of flight. It also defines a jump-gliding envelope that encompasses the range that can be achieved with jump-gliding robots and that can be used to evaluate the performance and improvement potential of jump-gliding robots. We present first a planar dynamic model and then a simplified closed form model, which allow for quantification of the distance travelled and the impact energy on landing. In order to validate the prediction of these models, we validate the model with experiments using a novel jump-gliding robot, named the 'EPFL jump-glider'. It has a mass of 16.5 g and is able to perform jumps from elevated positions, perform steered gliding flight, land safely and traverse on the ground by repetitive jumping. The experiments indicate that the developed jump-gliding model fits very well with the measured flight data using the EPFL jump-glider, confirming the benefits of jump-gliding locomotion to mobile robotics. The jump-glide envelope considerations indicate that the EPFL jump-glider, when traversing from a 2 m height, reaches 74.3% of optimal jump-gliding distance compared to pure jumping without a gliding phase which only reaches 33.4% of the optimal jump-gliding distance. Methods of further improving flight performance based on the models and inspiration from biological systems are presented providing mechanical design pathways to future jump-gliding robot designs.

  12. Comparison of antimicrobial resistance patterns in enterococci from intensive and free range chickens in Australia.

    Science.gov (United States)

    Obeng, Akua Serwaah; Rickard, Heather; Ndi, Olasumbo; Sexton, Margaret; Barton, Mary

    2013-02-01

    Resistance to antimicrobials in enterococci from poultry has been found throughout the world and is generally recognized as associated with antimicrobial use. This study was conducted to evaluate the phenotypic and genotypic profile of enterococcal isolates of intensive (indoor) and free range chickens from 2008/09 and 2000 in order to determine the patterns of antimicrobial resistance associated with different management systems. The minimum inhibitory concentrations in faecal enterococci isolates were determined by agar dilution. Resistance to bacitracin, ceftiofur, erythromycin, lincomycin, tylosin and tetracycline was more common among meat chickens (free range and intensive) than free range egg layers (Pfree range meat chickens.

  13. Jumping in Arithmetic

    NARCIS (Netherlands)

    Visser, Albert

    2014-01-01

    In this paper we study a new relation between sentences: the jump relation. The idea of the jump relation is based on an analysis of Feferman's Theorem that the inconsistency of a theory U is interpretable over U. The jump relation is based on a converse of Feferman's Theorem: if a sentence is

  14. Coalescence-induced nanodroplet jumping

    Science.gov (United States)

    Cha, Hyeongyun; Xu, Chenyu; Sotelo, Jesus; Chun, Jae Min; Yokoyama, Yukihiro; Enright, Ryan; Miljkovic, Nenad

    2016-10-01

    Water vapor condensation on superhydrophobic surfaces has received much attention in recent years due to the ability of such surfaces to shed microscale water droplets via coalescence-induced droplet jumping, resulting in heat transfer, anti-icing, and self-cleaning performance enhancement. Here we report the coalescence-induced removal of water nanodroplets (R ≈500 nm ) from superhydrophobic carbon nanotube (CNT) surfaces. The two-droplet coalescence time is measured for varying droplet Ohnesorge numbers, confirming that coalescence prior to jumping is governed by capillary-inertial dynamics. By varying the conformal hydrophobic coating thickness on the CNT surface, the minimum jumping droplet radius is shown to increase with increasing solid fraction and decreasing apparent advancing contact angle, allowing us to explore both hydrodynamic limitations stemming from viscous dissipation and surface adhesion limitations. We find that, even for the smallest nanostructure length scale (≤100 nm) and lowest surface adhesions, nonideal surface interactions and the evolved droplet morphology play defining roles in limiting the minimum size for jumping on real surfaces. The outcomes of this work demonstrate the ability to passively shed nanometric water droplets, which has the potential to further increase the efficiency of systems that can harness jumping droplets for a wide range of energy and water applications.

  15. Is pulmonary resistance constant, within the range of tidal volume ventilation, in patients with ARDS?

    Science.gov (United States)

    Mols, G; Kessler, V; Benzing, A; Lichtwarck-Aschoff, M; Geiger, K; Guttmann, J

    2001-02-01

    When managing patients with acute respiratory distress syndrome (ARDS), respiratory system compliance is usually considered first and changes in resistance, although recognized, are neglected. Resistance can change considerably between minimum and maximum lung volume, but is generally assumed to be constant in the tidal volume range (V(T)). We measured resistance during tidal ventilation in 16 patients with ARDS or acute lung injury by the slice method and multiple linear regression analysis. Resistance was constant within V(T) in only six of 16 patients. In the remaining patients, resistance decreased, increased or showed complex changes. We conclude that resistance within V(T) varies considerably from patient to patient and that constant resistance within V(T) is not always likely.

  16. Host range of antibiotic resistance genes in wastewater treatment plant influent and effluent.

    Science.gov (United States)

    Hultman, Jenni; Tamminen, Manu; Pärnänen, Katariina; Cairns, Johannes; Karkman, Antti; Virta, Marko

    2018-04-01

    Wastewater treatment plants (WWTPs) collect wastewater from various sources for a multi-step treatment process. By mixing a large variety of bacteria and promoting their proximity, WWTPs constitute potential hotspots for the emergence of antibiotic resistant bacteria. Concerns have been expressed regarding the potential of WWTPs to spread antibiotic resistance genes (ARGs) from environmental reservoirs to human pathogens. We utilized epicPCR (Emulsion, Paired Isolation and Concatenation PCR) to detect the bacterial hosts of ARGs in two WWTPs. We identified the host distribution of four resistance-associated genes (tetM, int1, qacEΔ1and blaOXA-58) in influent and effluent. The bacterial hosts of these resistance genes varied between the WWTP influent and effluent, with a generally decreasing host range in the effluent. Through 16S rRNA gene sequencing, it was determined that the resistance gene carrying bacteria include both abundant and rare taxa. Our results suggest that the studied WWTPs mostly succeed in decreasing the host range of the resistance genes during the treatment process. Still, there were instances where effluent contained resistance genes in bacterial groups not carrying these genes in the influent. By permitting exhaustive profiling of resistance-associated gene hosts in WWTP bacterial communities, the application of epicPCR provides a new level of precision to our resistance gene risk estimates.

  17. The effects of phosphatidic acid supplementation on strength, body composition, muscular endurance, power, agility, and vertical jump in resistance trained men.

    Science.gov (United States)

    Escalante, Guillermo; Alencar, Michelle; Haddock, Bryan; Harvey, Phillip

    2016-01-01

    Phosphatidic acid (PA) is a lipid messenger that has been shown to increase muscle protein synthesis via signaling stimulation of the mammalian target of rapamycin (mTOR). MaxxTOR® (MT) is a supplement that contains PA as the main active ingredient but also contains other synergistic mTOR signaling substances including L-Leucine, Beta-Hydroxy-Beta-Methylbutyrate (HMB), and Vitamin D3. Eighteen healthy strength-trained males were randomly assigned to a group that either consumed MT (n = 8, 22.0 +/- 2.5 years; 175.8 +/- 11.5 cm; 80.3 +/- 15.1 kg) or a placebo (PLA) (n = 10, 25.6 +/- 4.2 years; 174.8 +/- 9.0 cm; 88.6 +/- 16.6 kg) as part of a double-blind, placebo controlled pre/post experimental design. All participants volunteered to complete the three day per week resistance training protocol for the eight week study duration. To determine the effects of MT, participants were tested on one repetition maximum (1RM) leg press strength (LP), 1RM bench press strength (BP), push-ups to failure (PU), vertical jump (VJ), pro-agility shuttle time (AG), peak power output (P), lean body mass (LBM), fat mass (FM), and thigh muscle mass (TMM). Subjects were placed and monitored on an isocaloric diet consisting of 25 protein, 50 carbohydrates, and 25 % fat by a registered dietitian. Separate two-way mixed factorial repeated measures ANOVA's (time [Pre, Post] x group [MT and PLA] were used to investigate strength, body composition, and other performance changes. Post-hoc tests were applied as appropriate. Analysis were performed via SPSS with significance at (p ≤ 0.05). There was a significant main effect (F(1,16) = 33.30, p effect for LP (F(1,16) = 666.74, p < 0.001) and BP (F(1,16) = 126.36, p < 0.001) where both increased significantly more in MT than PLA group (p < 0.001). No significant differences between MT and PLA were noted for FM, TMM, VJ, AG, P, or PU. The results of this eight week trial suggest that the addition of

  18. Convergent evolution toward an improved growth rate and a reduced resistance range in Prochlorococcus strains resistant to phage.

    Science.gov (United States)

    Avrani, Sarit; Lindell, Debbie

    2015-04-28

    Prochlorococcus is an abundant marine cyanobacterium that grows rapidly in the environment and contributes significantly to global primary production. This cyanobacterium coexists with many cyanophages in the oceans, likely aided by resistance to numerous co-occurring phages. Spontaneous resistance occurs frequently in Prochlorococcus and is often accompanied by a pleiotropic fitness cost manifested as either a reduced growth rate or enhanced infection by other phages. Here, we assessed the fate of a number of phage-resistant Prochlorococcus strains, focusing on those with a high fitness cost. We found that phage-resistant strains continued evolving toward an improved growth rate and a narrower resistance range, resulting in lineages with phenotypes intermediate between those of ancestral susceptible wild-type and initial resistant substrains. Changes in growth rate and resistance range often occurred in independent events, leading to a decoupling of the selection pressures acting on these phenotypes. These changes were largely the result of additional, compensatory mutations in noncore genes located in genomic islands, although genetic reversions were also observed. Additionally, a mutator strain was identified. The similarity of the evolutionary pathway followed by multiple independent resistant cultures and clones suggests they undergo a predictable evolutionary pathway. This process serves to increase both genetic diversity and infection permutations in Prochlorococcus populations, further augmenting the complexity of the interaction network between Prochlorococcus and its phages in nature. Last, our findings provide an explanation for the apparent paradox of a multitude of resistant Prochlorococcus cells in nature that are growing close to their maximal intrinsic growth rates.

  19. Convergent evolution toward an improved growth rate and a reduced resistance range in Prochlorococcus strains resistant to phage

    Science.gov (United States)

    Avrani, Sarit; Lindell, Debbie

    2015-01-01

    Prochlorococcus is an abundant marine cyanobacterium that grows rapidly in the environment and contributes significantly to global primary production. This cyanobacterium coexists with many cyanophages in the oceans, likely aided by resistance to numerous co-occurring phages. Spontaneous resistance occurs frequently in Prochlorococcus and is often accompanied by a pleiotropic fitness cost manifested as either a reduced growth rate or enhanced infection by other phages. Here, we assessed the fate of a number of phage-resistant Prochlorococcus strains, focusing on those with a high fitness cost. We found that phage-resistant strains continued evolving toward an improved growth rate and a narrower resistance range, resulting in lineages with phenotypes intermediate between those of ancestral susceptible wild-type and initial resistant substrains. Changes in growth rate and resistance range often occurred in independent events, leading to a decoupling of the selection pressures acting on these phenotypes. These changes were largely the result of additional, compensatory mutations in noncore genes located in genomic islands, although genetic reversions were also observed. Additionally, a mutator strain was identified. The similarity of the evolutionary pathway followed by multiple independent resistant cultures and clones suggests they undergo a predictable evolutionary pathway. This process serves to increase both genetic diversity and infection permutations in Prochlorococcus populations, further augmenting the complexity of the interaction network between Prochlorococcus and its phages in nature. Last, our findings provide an explanation for the apparent paradox of a multitude of resistant Prochlorococcus cells in nature that are growing close to their maximal intrinsic growth rates. PMID:25922520

  20. Drop jumping. I. The influence of jumping technique on the biomechanics of jumping

    NARCIS (Netherlands)

    Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    In the literature, drop jumping is advocated as an effective exercise for athletes who prepare themselves for explosive activities. When executing drop jumps, different jumping techniques can be used. In this study, the influence of jumping technique on the biomechanics of jumping is investigated.

  1. Optimal Ski Jump

    Science.gov (United States)

    Rebilas, Krzysztof

    2013-01-01

    Consider a skier who goes down a takeoff ramp, attains a speed "V", and jumps, attempting to land as far as possible down the hill below (Fig. 1). At the moment of takeoff the angle between the skier's velocity and the horizontal is [alpha]. What is the optimal angle [alpha] that makes the jump the longest possible for the fixed magnitude of the…

  2. Scaled Jump in Gravity-Reduced Virtual Environments.

    Science.gov (United States)

    Kim, MyoungGon; Cho, Sunglk; Tran, Tanh Quang; Kim, Seong-Pil; Kwon, Ohung; Han, JungHyun

    2017-04-01

    The reduced gravity experienced in lunar or Martian surfaces can be simulated on the earth using a cable-driven system, where the cable lifts a person to reduce his or her weight. This paper presents a novel cable-driven system designed for the purpose. It is integrated with a head-mounted display and a motion capture system. Focusing on jump motion within the system, this paper proposes to scale the jump and reports the experiments made for quantifying the extent to which a jump can be scaled without the discrepancy between physical and virtual jumps being noticed by the user. With the tolerable range of scaling computed from these experiments, an application named retargeted jump is developed, where a user can jump up onto virtual objects while physically jumping in the real-world flat floor. The core techniques presented in this paper can be extended to develop extreme-sport simulators such as parasailing and skydiving.

  3. The effect of wind on jumping distance in ski jumping--fairness assessed.

    Science.gov (United States)

    Virmavirta, Mikko; Kivekäs, Juha

    2012-09-01

    The special wind compensation system recently adopted by Fédération Internationale de Ski (FIS; International Ski Federation) to consider the effects of changing wind conditions has caused some controversy. Here, the effect of wind on jumping distance in ski jumping was studied by means of computer simulation and compared with the wind compensation factors used by FIS during the World Cup season 2009/2010. The results showed clearly that the effect of increasing head/tail wind on jumping distance is not linear: +17.4 m/-29.1 m, respectively, for a wind speed of 3 m/s. The linear formula used in the trial period of the wind compensation system was found to be appropriate only for a limited range of jumping distances as the gradient of the landing slope slows down the rate of distance change in long jumps.

  4. Enhancing jump ground reaction forces in children through jump ...

    African Journals Online (AJOL)

    Enhancing jump ground reaction forces in children through jump training. ... South African Journal for Research in Sport, Physical Education and Recreation ... These improvements following simple jumps requiring minimal equipment strongly support the use of jump training to enhance athletic performance in children.

  5. There Are Quantum Jumps

    Directory of Open Access Journals (Sweden)

    Erkki J. Brändas

    2015-05-01

    Full Text Available In this communication we take up the age-old problem of the possibility to incorporate quantum jumps. Unusually, we investigate quantum jumps in an extended quantum setting, but one of rigorous mathematical significance. The general background for this formulation originates in the Balslev-Combes theorem for dilatation analytic Hamiltonians and associated complex symmetric representations. The actual jump is mapped into a Jordan block of order two and a detailed derivation is discussed for the case of the emission of a photon by an atom. The result can be easily reassigned to analogous cases as well as generalized to Segrè characteristics of arbitrary order.

  6. Natural selection on plant resistance to herbivores in the native and introduced range

    Science.gov (United States)

    Valverde, Pedro L.; Arroyo, Juan; Núñez-Farfán, Juan; Castillo, Guillermo; Calahorra, Adriana; Pérez-Barrales, Rocío; Tapia-López, Rosalinda

    2015-01-01

    When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of ‘release from natural enemies’. PMID:26205526

  7. Estimating the Transfer Range of Plasmids Encoding Antimicrobial Resistance in a Wastewater Treatment Plant Microbial Community

    DEFF Research Database (Denmark)

    Li, Liguan; Dechesne, Arnaud; He, Zhiming

    2018-01-01

    Wastewater treatment plants (WWTPs) have been suggested as reservoirs and sources of antibiotic resistance genes (ARGs) in the environment. In a WWTP ecosystem, human enteric and environmental bacteria are mixed and exposed to pharmaceutical residues, potentially favoring genetic exchange and thus...... sludge microbial community was challenged in standardized filter matings with one of three multidrug resistance plasmids (pKJK5, pB10, and RP4) harbored by Escherichia coli or Pseudomonas putida. Different donor–plasmid combinations had distinct transfer frequencies, ranging from 3 to 50 conjugation...

  8. Hydrodynamics of vertical jumping in Archer fish

    Science.gov (United States)

    Techet, Alexandra H.; Mendelson, Leah

    2017-11-01

    Vertical jumping for aerial prey from an aquatic environment requires both propulsive power and precise aim to succeed. Rapid acceleration to a ballistic velocity sufficient for reaching the prey height occurs before the fish leaves the water completely and experiences a thousandfold drop in force-producing ability. In addition to speed, accuracy and stability are crucial for successful feeding by jumping. This talk examines the physics of jumping using the archer fish as a model. Better known for their spitting abilities, archer fish will jump multiple body lengths out of the water for prey capture, from a stationary position just below the free surface. Modulation of oscillatory body kinematics and use of multiple fins for force production are identified as methods through which the fish can meet requirements for both acceleration and stabilization in limited space. Quantitative 3D PIV wake measurements reveal how variations in tail kinematics relate to thrust production throughout the course of a jumping maneuver and over a range of jump heights. By performing measurements in 3D, the timing, interactions, and relative contributions to thrust and lateral forces from each fin can be evaluated, elucidating the complex hydrodynamics that enable archer fish water exit.

  9. Validity and intra-rater reliability of MyJump app on iPhone 6s in jump performance.

    Science.gov (United States)

    Stanton, Robert; Wintour, Sally-Anne; Kean, Crystal O

    2017-05-01

    Smartphone applications are increasingly used by researchers, coaches, athletes and clinicians. The aim of this study was to examine the concurrent validity and intra-rater reliability of the smartphone-based application, MyJump, against laboratory-based force plate measurements. Cross sectional study. Participants completed counter-movement jumps (CMJ) (n=29) and 30cm drop jumps (DJ) (n=27) on a force plate which were simultaneously recorded using MyJump. To assess concurrent validity, jump height, derived from flight time acquired from each device, was compared for each jump type. Intra-rater reliability was determined by replicating data analysis of MyJump recordings on two occasions separated by seven days. CMJ and DJ heights derived from MyJump showed excellent agreement with the force plate (ICC values range from 0.991 for CMJ to 0.993) However mean DJ height from the force plate was significantly higher than MyJump (mean difference: 0.87cm, 95% CI: 0.69-1.04cm). Intra-rater reliability of MyJump for both CMJ and DJ was almost perfect (ICC values range from 0.997 for CMJ to 0.998 for DJ); however, mean CMJ and DJ jump height for Day 1 was significantly higher than Day 2 (CMJ: 0.43cm, 95% CI: 0.23-0.62cm); (DJ: 0.38cm, 95% CI: 0.23-0.53cm). The present study finds MyJump to be a valid and highly reliable tool for researchers, coaches, athletes and clinicians; however, systematic bias should be considered when comparing MyJump outputs to other testing devices. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. The acute effect of a plyometric stimulus on jump performance in professional rugby players.

    Science.gov (United States)

    Tobin, Daniel P; Delahunt, Eamonn

    2014-02-01

    Post-activation potentiation (PAP) is the elevation of motor performance to a higher level in response to a conditioning stimulus. Extensive research exists examining the PAP effect after a heavy resistance exercise. However, there is limited research examining the PAP effect after a plyometric stimulus. This study was designed to examine whether a plyometric stimulus could produce a PAP effect comparable to that typically reported with a heavy resistance protocol. Importantly, it was hypothesized that the PAP effect would exist without the same levels of acute fatigue resulting from a heavy stimulus, thus allowing improvement in performance within a short rest interval range. Twenty professional rugby players were recruited for the study. Subjects performed 2 countermovement jumps (CMJs) at baseline and at 1, 3, and 5 minutes after a plyometric stimulus consisting of 40 jumps. Two separate 1-way repeated-measures analyses of variance were conducted to compare the dependent variables CMJ height and peak force at the 4 time points. Results of the Bonferroni adjusted pairwise comparisons indicated that jump height and peak force before plyometric exercises were significantly lower than all other time points (p plyometric exercises causes a significant acute enhancement in CMJ height (p plyometric series induced an improvement in CMJ height comparable to that reported elsewhere after a heavy lifting stimulus but without the need for a prolonged rest interval. Performing repeated series of plyometric jumps appears to be an efficient method of taking advantage of the PAP phenomenon, thus possibly eliminating the need for a complex training protocol.

  11. Range Expansion and the Origin of USA300 North American Epidemic Methicillin-Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Lavanya Challagundla

    2018-01-01

    Full Text Available The USA300 North American epidemic (USA300-NAE clone of methicillin-resistant Staphylococcus aureus has caused a wave of severe skin and soft tissue infections in the United States since it emerged in the early 2000s, but its geographic origin is obscure. Here we use the population genomic signatures expected from the serial founder effects of a geographic range expansion to infer the origin of USA300-NAE and identify polymorphisms associated with its spread. Genome sequences from 357 isolates from 22 U.S. states and territories and seven other countries are compared. We observe two significant signatures of range expansion, including decreases in genetic diversity and increases in derived allele frequency with geographic distance from the Pennsylvania region. These signatures account for approximately half of the core nucleotide variation of this clone, occur genome wide, and are robust to heterogeneity in temporal sampling of isolates, human population density, and recombination detection methods. The potential for positive selection of a gyrA fluoroquinolone resistance allele and several intergenic regions, along with a 2.4 times higher recombination rate in a resistant subclade, is noted. These results are the first to show a pattern of genetic variation that is consistent with a range expansion of an epidemic bacterial clone, and they highlight a rarely considered but potentially common mechanism by which genetic drift may profoundly influence bacterial genetic variation.

  12. Broad-Host-Range IncP-1 plasmids and their resistance potential

    Directory of Open Access Journals (Sweden)

    Magdalena ePopowska

    2013-03-01

    Full Text Available The plasmids of the incompatibility group IncP-1, also called IncP, as extrachromosomal genetic elements can transfer and replicate virtually in all Gram-negative bacteria. They are composed of backbone genes that encode a variety of essential functions and accessory genes that have implications for human health and environmental bioremediation. Broad-host-range IncP plasmids are known to spread genes between distinct phylogenetic groups of bacteria. These genes often code for resistances to a broad spectrum of antibiotics, heavy metals and quaternary ammonium compounds used as disinfectants. The backbone of these plasmids carries modules that enable them to effectively replicate, move to a new host via conjugative transfer and to be stably maintained in bacterial cells. The adaptive, resistance and virulence genes are mainly located on mobile genetic elements integrated between the functional plasmid backbone modules. Environmental studies have demonstrated the wide distribution of IncP-like replicons in manure, soils and wastewater treatment plants. They also are present in strains of pathogenic or opportunistic bacteria, which can be a cause for concern, because they may encode multiresistance. Their broad distribution suggests that IncP plasmids play a crucial role in bacterial adaptation by utilizing horizontal gene transfer. This review summarizes the variety of genetic information and physiological functions carried by IncP plasmids, which can contribute to the spread of antibiotic and heavy metal resistance while also mediating the process of bioremediation of pollutants. Due to the location of the resistance genes on plasmids with a broad host range and the presence of transposons carrying these genes it seems that the spread of these genes would be possible and quite hazardous in infection control. Future studies are required to determine the level of risk of the spread of resistance genes located on these plasmids.

  13. Test-retest reliability of jump execution variables using mechanography: a comparison of jump protocols.

    Science.gov (United States)

    Fitzgerald, John S; Johnson, LuAnn; Tomkinson, Grant; Stein, Jesse; Roemmich, James N

    2018-05-01

    Mechanography during the vertical jump may enhance screening and determining mechanistic causes underlying physical performance changes. Utility of jump mechanography for evaluation is limited by scant test-retest reliability data on force-time variables. This study examined the test-retest reliability of eight jump execution variables assessed from mechanography. Thirty-two women (mean±SD: age 20.8 ± 1.3 yr) and 16 men (age 22.1 ± 1.9 yr) attended a familiarization session and two testing sessions, all one week apart. Participants performed two variations of the squat jump with squat depth self-selected and controlled using a goniometer to 80º knee flexion. Test-retest reliability was quantified as the systematic error (using effect size between jumps), random error (using coefficients of variation), and test-retest correlations (using intra-class correlation coefficients). Overall, jump execution variables demonstrated acceptable reliability, evidenced by small systematic errors (mean±95%CI: 0.2 ± 0.07), moderate random errors (mean±95%CI: 17.8 ± 3.7%), and very strong test-retest correlations (range: 0.73-0.97). Differences in random errors between controlled and self-selected protocols were negligible (mean±95%CI: 1.3 ± 2.3%). Jump execution variables demonstrated acceptable reliability, with no meaningful differences between the controlled and self-selected jump protocols. To simplify testing, a self-selected jump protocol can be used to assess force-time variables with negligible impact on measurement error.

  14. Atrial Natriuretic Peptide in the high normal range is associated with lower prevalence of insulin resistance

    DEFF Research Database (Denmark)

    Jujić, Amra; Nilsson, Peter M; Persson, Margaretha

    2016-01-01

    plasma levels of mid-regional proANP (MR-proANP) are associated with insulin resistance and post challenge incretin secretion after long-term follow-up. Design/Setting/Patients MR-proANP was measured in 2243 non-diabetic individuals at baseline examination of Malmö Diet and Cancer Cardiovascular cohort...... was inversely associated with insulin resistance calculated as HOMA-IR (per 1 SD change β= -0.066, p-value 0.001) at follow-up. Logistic regression analysis showed that each 1 SD increment of baseline ANP levels resulted in lower risk of belonging to upper quartile of HOMA-IR at follow-up (OR 0.88; CI 95 % 0...... after 75g glucose intake at 16.5 years of follow up. CONCLUSION: Midlife exposure to ANP within the high normal range is associated with lower risk of insulin resistance. Further, midlife exposure to ANP within the high normal range is associated with greater post challenge GIP secretion at follow...

  15. Electrical resistivity anisotropy of osmium single crystals in the range 4,2 to 300 K

    International Nuclear Information System (INIS)

    Volkenshtejn, N.V.; Dyakina, V.P.; Dyakin, V.V.; Startsev, V.E.; Cherepanov, V.I.; Azhazha, V.M.; Kovtun, G.P.; Elenskij, V.A.; AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst.)

    1981-01-01

    Electrical resistivity and size effect anisotropies of pure osmium single crystals with rhosub(273.2/rhosub(4.2)2600 were investigated in the temperature range 4.2 to 300 K. It is found that the electrical resistivity anisotropy (αT)=rhosub( )/rhosub( ) is less than unit and has a maximum at T approximately 50 K; the size effect anisotropy (rho1)sub( )/(rho1)sub( ) is 0.39+-0.07 at T=4.2 K; at liquid helium temperature, the dependence of thin samples is controlled by the scattering of conduction electrons by the surface of the sample. The results are discussed for the specific shape of the Fermi surface geometry of osmium with an account for the scattering processes of conduction electrons by phonons and by surface of the sample

  16. Why is countermovement jump height greater than squat jump height?

    NARCIS (Netherlands)

    Bobbert, Maarten F.; Gerritsen, Karin G M; Litjens, Maria C A; Van Soest, Arthur J.

    1996-01-01

    In the literature, it is well established that subjects are able to jump higher in a countermovement jump (CMJ) than in a squat jump (SJ). The purpose of this study was to estimate the relative contribution of the time available for force development and the storage and reutilization of elastic

  17. Drop Jumping as a Training Method for Jumping Ability

    NARCIS (Netherlands)

    Bobbert, Maarten F.

    1990-01-01

    Vertical jumping ability is of importance for good performance in sports such as basketball and volleyball. Coaches are in need of exercises that consume only little time and still help to improve their players’ jumping ability, without involving a high risk of injury. Drop jumping is assumed to

  18. THE EFFECTS OF SINGLE VERSUS REPEATED PLYOMETRICS ON LANDING BIOMECHANICS AND JUMPING PERFORMANCE IN MEN

    Directory of Open Access Journals (Sweden)

    H. Makaruk

    2014-07-01

    Full Text Available The aim of this study was to examine the chronic effects of single and repeated jumps training on vertical landing force (VGRF and jump height in untrained men. The VGRF and jump height were compared after a six-week plyometric training programme containing single and repeated jumps, together with two additional parameters: landing time (LT and range of the knee flexion during landing (KF. Thirty-six untrained physical education students with a plyometric training background were randomly assigned to a single jump group (SJG, n =12, repeated jumps group (RJG, n =12, and control group (CON, n =12. The SJG performed only single jumps, the RJG executed repeated (consecutive jumps, whereas the CON did not perform any exercises at all. A countermovement jump (CMJ, repeated countermovement jumps (RCMJ, and a drop jump (DJ were tested before and after the training. Only the RJG showed a significantly reduced VGRF (p<0.05 in all tests. Both plyometric groups significantly improved (p<0.05 their jump height in all tests. The LT was significantly greater in the RJG, compared to the SJG, in all tests. The KF was also significantly (p<0.05 greater in the RJG than in the SJG for CMJ and RCMJ. The results suggest that repeated jumps are beneficial for simultaneous landing force reduction and jumping performance enhancement.

  19. Jump into Action

    Science.gov (United States)

    Ball, Stephen; Cohen, Ann; Meyer, Margaret

    2012-01-01

    Jump Into Action (JIA) is a school-based team-taught program to help fifth-grade students make healthy food choices and be more active. The JIA team (physical education teacher, classroom teacher, school nurse, and parent) work together to provide a supportive environment as students set goals to improve food choices and increase activity.…

  20. SARS – virus jumps species

    Indian Academy of Sciences (India)

    SARS – virus jumps species. Coronavirus reshuffles genes; Rotteir et al, Rotterdam showed the virus to jump from cats to mouse cells after single gene mutation ? Human disease due to virus jumping from wild or domestic animals; Present favourite animal - the cat; - edible or domestic.

  1. Resistance to alveolar shape change limits range of force propagation in lung parenchyma.

    Science.gov (United States)

    Ma, Baoshun; Smith, Bradford J; Bates, Jason H T

    2015-06-01

    We have recently shown that if the lung parenchyma is modeled in 2 dimensions as a network of springs arranged in a pattern of repeating hexagonal cells, the distortional forces around a contracting airway propagate much further from the airway wall than classic continuum theory predicts. In the present study we tested the hypothesis that this occurs because of the negligible shear modulus of a hexagonal spring network. We simulated the narrowing of an airway embedded in a hexagonal network of elastic alveolar walls when the hexagonal cells of the network offered some resistance to a change in shape. We found that as the forces resisting shape change approach about 10% of the forces resisting length change of an individual spring the range of distortional force propagation in the spring network fell of rapidly as in an elastic continuum. We repeated these investigations in a 3-dimensional spring network composed of space-filling polyhedral cells and found similar results. This suggests that force propagation away from a point of local parenchymal distortion also falls off rapidly in real lung tissue. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Crown sheath rot of rice: host-range and varietal resistance to Gaeumannomyces graminis var. graminis

    Directory of Open Access Journals (Sweden)

    Cecília do Nascimento Peixoto

    2014-09-01

    Full Text Available Several gramineous plants occurring in rice fields show symptoms of crown sheath rot of rice, caused by Gaeumannomyces graminis var. graminis (Ggg, under natural conditions of infection. The pathogenicity of the Ggg-a 01 isolate, collected from rice, was tested on seven grass species and eight cereals, under greenhouse conditions, in order to get information on host-range and resistance of rice genotypes to crown sheath rot. The inoculation tests showed that the rice isolate was pathogenic to weeds such as Echinochloa crusgalli, Pennisetum setosum, Brachiaria sp., Digitaria horizontalis, Brachiaria plantaginea, Eleusine indica and Cenchrus echinatus, and that these species are potential hosts to the pathogen. Winter cereals such as wheat, oat, rye, barley and triticale, as well as sorghum, maize and millet, presented different degrees of susceptibility to the Ggg-a isolate. Significant differences were observed in relation to lesion height and production of hyphopodia and perithecia on culms. Perithecia were not observed on millet, sorghum, southern sandbur and maize. The resistance of 58 upland rice genotypes was tested, and the SCIA16 and SCIA08 genotypes presented lesion height significantly smaller, being considered resistant, when compared to the highly susceptible CNAS10351 genotype.

  3. Vertical jumping tests in volleyball: reliability, validity, and playing-position specifics.

    Science.gov (United States)

    Sattler, Tine; Sekulic, Damir; Hadzic, Vedran; Uljevic, Ognjen; Dervisevic, Edvin

    2012-06-01

    Vertical jumping is known to be important in volleyball, and jumping performance tests are frequently studied for their reliability and validity. However, most studies concerning jumping in volleyball have dealt with standard rather than sport-specific jumping procedures and tests. The aims of this study, therefore, were (a) to determine the reliability and factorial validity of 2 volleyball-specific jumping tests, the block jump (BJ) test and the attack jump (AJ) test, relative to 2 frequently used and systematically validated jumping tests, the countermovement jump test and the squat jump test and (b) to establish volleyball position-specific differences in the jumping tests and simple anthropometric indices (body height [BH], body weight, and body mass index [BMI]). The BJ was performed from a defensive volleyball position, with the hands positioned in front of the chest. During an AJ, the players used a 2- to 3-step approach and performed a drop jump with an arm swing followed by a quick vertical jump. A total of 95 high-level volleyball players (all men) participated in this study. The reliability of the jumping tests ranged from 0.97 to 0.99 for Cronbach's alpha coefficients, from 0.93 to 0.97 for interitem correlation coefficients and from 2.1 to 2.8 for coefficients of variation. The highest reliability was found for the specific jumping tests. The factor analysis extracted one significant component, and all of the tests were highly intercorrelated. The analysis of variance with post hoc analysis showed significant differences between 5 playing positions in some of the jumping tests. In general, receivers had a greater jumping capacity, followed by libero players. The differences in jumping capacities should be emphasized vis-a-vis differences in the anthropometric measures of players, where middle hitters had higher BH and body weight, followed by opposite hitters and receivers, with no differences in the BMI between positions.

  4. A low-noise wide dynamic range CMOS image sensor with low and high temperatures resistance

    Science.gov (United States)

    Mizobuchi, Koichi; Adachi, Satoru; Tejada, Jose; Oshikubo, Hiromichi; Akahane, Nana; Sugawa, Shigetoshi

    2008-02-01

    A temperature-resistant 1/3 inch SVGA (800×600 pixels) 5.6 μm pixel pitch wide-dynamic-range (WDR) CMOS image sensor has been developed using a lateral-over-flow-integration-capacitor (LOFIC) in a pixel. The sensor chips are fabricated through 0.18 μm 2P3M process with totally optimized front-end-of-line (FEOL) & back-end-of-line (BEOL) for a lower dark current. By implementing a low electrical field potential design for photodiodes, reducing damages, recovering crystal defects and terminating interface states in the FEOL+BEOL, the dark current is improved to 12 e - /pixel-sec at 60 deg.C with 50% reduction from the previous very-low-dark-current (VLDC) FEOL and its contribution to the temporal noise is improved. Furthermore, design optimizations of the readout circuits, especially a signal-and noise-hold circuit and a programmable-gain-amplifier (PGA) are also implemented. The measured temporal noise is 2.4 e -rms at 60 fps (:36 MHz operation). The dynamic-range (DR) is extended to 100 dB with 237 ke - full well capacity. In order to secure the temperature-resistance, the sensor chip also receives both an inorganic cap onto micro lens and a metal hermetic seal package assembly. Image samples at low & high temperatures show significant improvement in image qualities.

  5. Nordic ski jumping fatalities in the United States: a 50-year summary.

    Science.gov (United States)

    Wright, J R

    1988-06-01

    Nordic ski-jumping fatalities are rare events. Six jumping fatalities have occurred in the United States during the past 50 years. The fatality rate for nordic ski jumping, estimated to be roughly 12 fatalities/100,000 participants annually, appears to be within the range of fatality rates for other "risky" outdoor sports. Cervical fractures appear to be the most frequent fatal ski-jumping injury.

  6. Comparison of stretch reflex responses evoked during drop jumping in highly skilled atheles versus untrained subjects.

    Science.gov (United States)

    Judge, L W; Burke, J R

    2015-06-01

    The purpose of the study was to describe changes in the excitability of the stretch reflex response (SRR) during different drop jumps as a function of training background and as an adaptation to a preseason sport-specific resistance training program. Twelve collegiate field event athletes (discus, hammer, javelin, shot put, and weight; 9 males and 3 females) and 12 college-aged control subjects performed the following three jumps: (1) countermovement jump (CMJ); (2) countermovement drop jump; and (3) bounce-drop jump (BDJ). Neuromechanical changes in the performance of drop jumps by athletes were measured during the sport-specific resistance training program. Pre-post testing of drop jump performance by control subjects was included for comparison. For each jump trial, ground reaction forces (GRF), electromyograms (EMG) and cinematographic data were collected. There were no training adaptations. However, jump heights were greater for the athletes than the controls among the different jumps with the jump heights for all subjects being less during the BDJ than CMJ and CDJ. In athletes only, there was a differential modulation of the SRR from the gastrocnemius muscle with different levels of background muscle activity for the CDJ and BDJ. There were changes in excitability of SRR from the gastrocnemius muscle as a function of training background. Interrelated neuromechanical mechanisms to include landing biomechanics, intrinsic musculotendinous tissue properties of the ankle, and centrally regulated motor commands may underlie the facilitation of the SRR from the gastrocnemius muscle in athletes as compared to controls.

  7. Froghopper-inspired direction-changing concept for miniature jumping robots.

    Science.gov (United States)

    Jung, Gwang-Pil; Cho, Kyu-Jin

    2016-09-14

    To improve the maneuverability and agility of jumping robots, several researchers have studied steerable jumping mechanisms. This steering ability enables robots to reach a particular target by controlling their jumping direction. To this end, we propose a novel direction-changing concept for miniature jumping robots. The proposed concept allows robots to be steerable while exerting minimal effects on jumping performance. The key design principles were adopted from the froghopper's power-producing hind legs and the moment cancellation accomplished by synchronized leg operation. These principles were applied via a pair of symmetrically positioned legs and conventional gears, which were modeled on the froghopper's anatomy. Each leg has its own thrusting energy, which improves jumping performance by allowing the mechanism to thrust itself with both power-producing legs. Conventional gears were utilized to simultaneously operate the legs and cancel out the moments that they induce, which minimizes body spin. A prototype to verify the concept was built and tested by varying the initial jumping posture. Three jumping postures (synchronous, asynchronous, and single-legged) were tested to investigate how synchronization and moment cancelling affect jumping performance. The results show that synchronous jumping allows the mechanism to change direction from -40° to 40°, with an improved take-off speed. The proposed concept can only be steered in a limited range of directions, but it has potential for use in miniature jumping robots that can change jumping direction with a minimal drop in jumping performance.

  8. Undular Hydraulic Jump

    Directory of Open Access Journals (Sweden)

    Oscar Castro-Orgaz

    2015-04-01

    Full Text Available The transition from subcritical to supercritical flow when the inflow Froude number Fo is close to unity appears in the form of steady state waves called undular hydraulic jump. The characterization of the undular hydraulic jump is complex due to the existence of a non-hydrostatic pressure distribution that invalidates the gradually-varied flow theory, and supercritical shock waves. The objective of this work is to present a mathematical model for the undular hydraulic jump obtained from an approximate integration of the Reynolds equations for turbulent flow assuming that the Reynolds number R is high. Simple analytical solutions are presented to reveal the physics of the theory, and a numerical model is used to integrate the complete equations. The limit of application of the theory is discussed using a wave breaking condition for the inception of a surface roller. The validity of the mathematical predictions is critically assessed using physical data, thereby revealing aspects on which more research is needed

  9. Risk of Transmission of Antimicrobial Resistant Escherichia coli from Commercial Broiler and Free-Range Retail Chicken in India

    OpenAIRE

    Arif Hussain; Sabiha Shaik; Amit Ranjan; Nishant Nandanwar; Sumeet K. Tiwari; Mohammad Majid; Ramani Baddam; Ramani Baddam; Insaf A. Qureshi; Torsten Semmler; Lothar H. Wieler; Mohammad A. Islam; Dipshikha Chakravortty; Niyaz Ahmed; Niyaz Ahmed

    2017-01-01

    Multidrug-resistant Escherichia coli infections are a growing public health concern. This study analyzed the possibility of contamination of commercial poultry meat (broiler and free-range) with pathogenic and or multi-resistant E. coli in retail chain poultry meat markets in India. We analyzed 168 E. coli isolates from broiler and free-range retail poultry (meat/ceca) sampled over a wide geographical area, for their antimicrobial sensitivity, phylogenetic groupings, virulence determinants, e...

  10. Choice of jumping strategy in two standard jumps, squat and countermovement jump--effect of training background or inherited preference?

    DEFF Research Database (Denmark)

    Ravn, Susanne; Voigt, M; Simonsen, Erik Bruun

    1999-01-01

    Six male subjects, three professional ballet dancers and three elite volleyball players, performed maximal vertical jumps from 1) a static preparatory position (squat jump), 2) starting with a countermovement (countermovement jump) and 3) a specific jump for ballet and for volleyball, respectively....... The jumps were recorded on highspeed film (500 Hz) combined with registration of ground reaction forces, and net joint moments were calculated by inverse dynamics. The purpose was to investigate the choice of strategy in two standard jumps, squat jump and countermovement jump. The volleyball jump...

  11. Methicillin resistance gene diversity in staphylococci isolated from captive and free-ranging wallabies

    Directory of Open Access Journals (Sweden)

    Michelle M. S. Chen

    2016-05-01

    Full Text Available Background: Infection with methicillin-resistant staphylococci (MRS can be life-threatening in humans and its presence in animals is a cause for public health concern. The aim of this study was to measure the prevalence of MRS in captive and free-ranging wallabies over a 16-month period in South Australia, Australia. Materials and methods: Eighty-nine purified staphylococcal isolates recovered from 98 captive and free-ranging wallabies' anterior nasal swabs were used in this study. All isolates were tested for the presence of the mecA, mecA1, and mecC genes. Multiplex PCR-directed SCCmec-typing, ccrB-typing, and determination of the minimal inhibitory concentration of oxacillin were performed on mec-positive isolates. Results and discussion: In total, 11 non-Staphylococcus aureus MRS were isolated from 7 out of 98 animals, corresponding to a 7.1% carriage rate. The SCCmec types I, III, and V were identified by multiplex PCR and sequencing of the ccrB gene. This is the first report of MRS carriage in both captive and free-ranging wallabies in Australia. These data demonstrate a low prevalence of MRS and no association between wallaby captivity status and MRS carriage could be assigned. These animals may act as a reservoir for the exchange of genetic elements between staphylococci. Furthermore, the mecA genes of animal isolates were identical to that found in human MRS strains and thus the possibility of zoonotic transfer must be considered.

  12. and the CMJ jump height

    Directory of Open Access Journals (Sweden)

    Struzik Artur

    2016-04-01

    Full Text Available Study aim: The elastic potential energy accumulated in the musculotendinous units during the countermovement phase of a jump adds up to the energy supplied by the contracting muscles used in the take-off phase. Consequently, the total mechanical energy used during the jump may reach higher values. Stiffness represents a quantitative measure of a body’s elastic properties. Therefore, the aim of this study was to establish the relationship between leg stiffness and the countermovement jump height.

  13. EFFECTS OF MAXIMAL SQUAT EXERCISE TESTING ON VERTICAL JUMP PERFORMANCE IN AMERICAN COLLEGE FOOTBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Jay R. Hoffman

    2007-03-01

    on the first day of pre-season training camp. All athletes provided their informed consent as part of their sport requirements consistent with the college's Institutional Review Board's policies for use of human subjects in research. They were familiar with all testing protocols and had performed these assessments for the previous 2 - 6 years. All athletes reported to the athletic training facility for strength and vertical jump testing and performed a 5-min warm-up (pedaling at 60 rpm at 300 kg·m·min-1 interspersed with five all-out sprints during the last 5-s of each minute on a cycle ergometer prior to testing. Following the warm-up the athletes performed two countermovement vertical jumps. The higher of the two trials was recorded. The athletes then performed a 1-RM strength test for the barbell back squat exercise. Following a 5-minute rest interval, each athlete performed an additional countermovement vertical jump trial. The 1-RM squat test was performed using methods previously described by Hoffman, 2006. Each athlete performed a warm-up set using a resistance that was approximately 40-60% of his perceived maximum, and then performed three-to- four subsequent trials to determine the 1-RM. A 3 - 5 minute rest period was provided between each trial. The squat exercise required the athlete to place an Olympic bar across the trapezius muscle at a self-selected location. The athlete then descended to the parallel position which was attained when the greater trochanter of the femur reached the same level as the knee. The athlete then ascended until full knee extension. Trials not meeting the range of motion criteria were discarded.The counter-movement vertical jump height was measured using a VertecTM (Sports Imports, Columbus, OH. Prior to testing, each athlete's standing vertical reach height was determined. Vertical jump height was calculated by subtracting the standing reach height from the jump height. Power outputs were calculated based upon the formula of

  14. Time-resolved methods in biophysics. 9. Laser temperature-jump methods for investigating biomolecular dynamics.

    Science.gov (United States)

    Kubelka, Jan

    2009-04-01

    Many important biochemical processes occur on the time-scales of nanoseconds and microseconds. The introduction of the laser temperature-jump (T-jump) to biophysics more than a decade ago opened these previously inaccessible time regimes up to direct experimental observation. Since then, laser T-jump methodology has evolved into one of the most versatile and generally applicable methods for studying fast biomolecular kinetics. This perspective is a review of the principles and applications of the laser T-jump technique in biophysics. A brief overview of the T-jump relaxation kinetics and the historical development of laser T-jump methodology is presented. The physical principles and practical experimental considerations that are important for the design of the laser T-jump experiments are summarized. These include the Raman conversion for generating heating pulses, considerations of size, duration and uniformity of the temperature jump, as well as potential adverse effects due to photo-acoustic waves, cavitation and thermal lensing, and their elimination. The laser T-jump apparatus developed at the NIH Laboratory of Chemical Physics is described in detail along with a brief survey of other laser T-jump designs in use today. Finally, applications of the laser T-jump in biophysics are reviewed, with an emphasis on the broad range of problems where the laser T-jump methodology has provided important new results and insights into the dynamics of the biomolecular processes.

  15. Take-off analysis of the Olympic ski jumping competition (HS-106m).

    Science.gov (United States)

    Virmavirta, Mikko; Isolehto, Juha; Komi, Paavo; Schwameder, Hermann; Pigozzi, Fabio; Massazza, Giuseppe

    2009-05-29

    The take-off phase (approximately 6m) of the jumps of all athletes participating in the individual HS-106m hill ski jumping competition at the Torino Olympics was filmed with two high-speed cameras. The high altitude of the Pragelato ski jumping venue (1600m) and slight tail wind in the final jumping round were expected to affect the results of this competition. The most significant correlation with the length of the jump was found in the in-run velocity (r=0.628, pski jumping, and suggests that good jumpers simply had smaller friction between their skis and the in-run tracks and/or the aerodynamic quality of their in-run position was better. Angular velocity of the hip joint of the best jumpers was also correlated with jumping distance (r=0.651, pjumped approximately the same distance. This certainly improves the interests in ski jumping among athletes and spectators. The comparison between the take-off techniques of the best jumpers showed that even though the more marked upper body movement creates higher air resistance, it does not necessarily result in shorter jumping distance if the exposure time to high air resistance is not too long. A comparison between the first and second round jumps of the same jumpers showed that the final results in this competition were at least partly affected by the wind conditions.

  16. Metagenomic profiling of historic Colorado Front Range flood impact on distribution of riverine antibiotic resistance genes

    Science.gov (United States)

    Garner, Emily; Wallace, Joshua S.; Argoty, Gustavo Arango; Wilkinson, Caitlin; Fahrenfeld, Nicole; Heath, Lenwood S.; Zhang, Liqing; Arabi, Mazdak; Aga, Diana S.; Pruden, Amy

    2016-12-01

    Record-breaking floods in September 2013 caused massive damage to homes and infrastructure across the Colorado Front Range and heavily impacted the Cache La Poudre River watershed. Given the unique nature of this watershed as a test-bed for tracking environmental pathways of antibiotic resistance gene (ARG) dissemination, we sought to determine the impact of extreme flooding on ARG reservoirs in river water and sediment. We utilized high-throughput DNA sequencing to obtain metagenomic profiles of ARGs before and after flooding, and investigated 23 antibiotics and 14 metals as putative selective agents during post-flood recovery. With 277 ARG subtypes identified across samples, total bulk water ARGs decreased following the flood but recovered to near pre-flood abundances by ten months post-flood at both a pristine site and at a site historically heavily influenced by wastewater treatment plants and animal feeding operations. Network analysis of de novo assembled sequencing reads into 52,556 scaffolds identified ARGs likely located on mobile genetic elements, with up to 11 ARGs per plasmid-associated scaffold. Bulk water bacterial phylogeny correlated with ARG profiles while sediment phylogeny varied along the river’s anthropogenic gradient. This rare flood afforded the opportunity to gain deeper insight into factors influencing the spread of ARGs in watersheds.

  17. More Puddle Jumping

    Science.gov (United States)

    Attari, Babak; Weislogel, Mark; Wollman, Andrew; Chen, Yongkang; Snyder, Trevor

    2016-11-01

    Large droplets and puddles jump spontaneously from sufficiently hydrophobic surfaces during routine drop tower tests. The simple low-cost passive mechanism can in turn be used as an experimental device to investigate dynamic droplet phenomena for drops up to 10,000 times larger than their normal terrestrial counterparts. We provide or confirm quick and qualitative design guides for such 'drop shooters' as employed in drop tower tests including relationships to predict droplet ejection durations and velocities as functions of drop volume, surface texture, surface contour, wettability pattern, drop volume, and fluid properties including contact angle. The latter are determined via profile image comparisons with numerical equilibrium interface computations. Water drop volumes of 0.04 to 400 mL at ejection speeds of -0.007 to 0.12 m/s are demonstrated. An example application of the puddle jump method is made to the classic problem of regime mapping for low-gravity phase change heat transfer for large impinging drops. Many other candidate problems might be identified.

  18. Hydraulic jumps in a channel

    DEFF Research Database (Denmark)

    Bonn, D.; Andersen, Anders Peter; Bohr, Tomas

    2009-01-01

    We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected...

  19. Model for polygonal hydraulic jumps

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Watanabe, Shinya; Bohr, Tomas

    2012-01-01

    We propose a phenomenological model for the polygonal hydraulic jumps discovered by Ellegaard and co-workers [Nature (London) 392, 767 (1998); Nonlinearity 12, 1 (1999); Physica B 228, 1 (1996)], based on the known flow structure for the type-II hydraulic jumps with a "roller" (separation eddy...

  20. Mechanics of jumping on water

    Science.gov (United States)

    Kim, Ho-Young; Amauger, Juliette; Jeong, Han-Bi; Lee, Duck-Gyu; Yang, Eunjin; Jablonski, Piotr G.

    2017-10-01

    Some species of semiaquatic arthropods including water striders and springtails can jump from the water surface to avoid sudden dangers like predator attacks. It was reported recently that the jump of medium-sized water striders is a result of surface-tension-dominated interaction of thin cylindrical legs and water, with the leg movement speed nearly optimized to achieve the maximum takeoff velocity. Here we describe the mathematical theories to analyze this exquisite feat of nature by combining the review of existing models for floating and jumping and the introduction of the hitherto neglected capillary forces at the cylinder tips. The theoretically predicted dependence of body height on time is shown to match the observations of the jumps of the water striders and springtails regardless of the length of locomotory appendages. The theoretical framework can be used to understand the design principle of small jumping animals living on water and to develop biomimetic locomotion technology in semiaquatic environments.

  1. Validity of a jump training apparatus using Wii Balance Board.

    Science.gov (United States)

    Yamamoto, Keizo; Matsuzawa, Mamoru

    2013-05-01

    The dynamic quantification of jump ability is useful for sports performance evaluation. We developed a force measurement system using the Wii Balance Board (WBB). This study was conducted to validate the system in comparison with a laboratory-grade force plate (FP). For a static validation, weights of 10-180kg were put progressively on the WBB put on the FP. The vertical component of the ground reaction force (vGRF) was measured using both devices and compared. For the dynamic validation, 10 subjects without lower limb pathology participated in the study and performed vertical jumping twice on the WBB on the FP. The range of analysis was set from the landing after the first jump to taking off of the second jump. The peak values during the landing phase and jumping phase were obtained and the force-time integral (force impulse) was measured. The relations of the values measured using each device were compared using Pearson's correlation coefficient test and Bland-Altman plots (BAP). Significant correlation (P<.01, r=.99) was found between the values of both devices in the static and the dynamic test. Examination of the BAP revealed a proportion error in the landing phase and showed no relation in the jumping phase between the difference and the mean in the dynamic test. The WBB detects the vGRF in the jumping phase with high precision. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. An algorithm to remove fringe jumps and its application to microwave reflectometry

    International Nuclear Information System (INIS)

    Ejiri, A.; Kawahata, K.; Shinohara, K.

    1997-01-01

    In some plasma discharges, the phase measured by microwave reflectometry has many fringe (2π radians) jumps. A new algorithm to detect and remove fringe jumps has been developed, and applied to the data in the JIPP TII-U tokamak. Using this algorithm, quantitative properties of fringe jumps, and their effects on the analysis of phase fluctuations are investigated. It was found that the occurrence of fringe jumps obeys a Poisson process, and the time scale of jumps is distributed over a wide range. Fringe jumps affect mainly the low-frequency components of phase fluctuations. Comparison of the phase corrected by the algorithm and the phase calculated from the time smoothed signals indicates that time smoothing (or frequency filtering) is an effective way to obtain information concerning the macroscopic density profile. Fringe jump and phase runaway can be phenomenologically explained by the distribution of the complex amplitude of the reflected wave. (author)

  3. Results of two years of water training on jump height in postmenopausal women with moderate hip risk fracture

    OpenAIRE

    María Carrasco Poyatos; Manuel Vaquero Abellán

    2010-01-01

    The aim of the present study was to investigate the effect of a water-based calisthenics and resistance program on jump height in postmenopausal women with moderate hip risk fracture. 39 women were divided into three groups: swimming group (GN; n = 17), calisthenics and resistance group (GIR; n = 14), and control group (GC; n = 8). Body composition test included body mass index (IMC) and waist to hip ratio (ICC). Jump height was assessed by a countermovement jump (CMJ). GN showed a significan...

  4. Effect of Load Range on Probabilistic Fatigue Crack Growth Resistance in Flux Cored Arc Welded Api 2w GR. Steel

    Science.gov (United States)

    Kim, Seon-Jin; Sohn, Sang-Hoon; Sohn, Hye-Jeong

    The aim of this paper is to investigate the effects of the load range on the spatial variation of fatigue crack growth resistance in three different zones, WM, HAZ and BM for flux cored arc welded API 2W Gr. 50 steel using the stochastic model based on reliability theory. Experimental fatigue crack growth tests were performed on ASTM standard CT specimens. The results indicates that the load range has strong dependency on probabilistic fatigue crack growth for the three different zones WM, HAZ and BM, and also the spatial variation of fatigue crack growth resistance.

  5. Change in Counter movement Jump Strategy by Varying Jump Height Based on Simplified Framework for Center of Mass Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seyoung [Korea Institute of Machinery and Materials(KIMM), Daejeon (Korea, Republic of)

    2017-04-15

    In this study, we investigated how a jumping strategy changes with an increase in the vertical jump height for a resultant ground reaction force (GRF) vector. We expected that the resultant force vector between two sequential motion phases (i.e., countermovement and push-off) of the counter movement jump would significantly change with the vertical jump height to take advantage of the resulting supportive force (i.e., an initial push-off force larger than the body weight) through the counter movement phase. Nine healthy young subjects were instructed to jump straight up to five different height levels ranging from 191 cm to 221 cm, and the kinematic and kinetic data were obtained in regular trials. The results showed that a lower center of mass position and larger resultant force vector were clearly observed in a higher jump, implying that the counter movement strategy changed with the vertical jump height to prepare for sufficient joint deviation and obtain a force advantage for larger push-off work.

  6. Comparison of the Hang High-Pull and Loaded Jump Squat for the Development of Vertical Jump and Isometric Force-Time Characteristics.

    Science.gov (United States)

    Oranchuk, Dustin J; Robinson, Tracey L; Switaj, Zachary J; Drinkwater, Eric J

    2017-04-15

    Weightlifting movements have high skill demands and require expert coaching. Loaded jumps have a comparably lower skill demand, but may be similarly effective for improving explosive performance. The purpose of this study was to compare vertical jump performance, isometric force, and rate of force development (RFD) following a ten-week intervention employing the hang high-pull (hang-pull) or trap-bar jump squat (jump-squat). Eighteen NCAA Division II swimmers (8 males, 10 females) with at least one year of resistance training experience volunteered to participate. Testing included the squat jump (SJ), countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP). Vertical ground reaction forces were analyzed to obtain jump height and relative peak power. Relative peak force, peak RFD and relative force at five time bands were obtained from the IMTP. Subjects were randomly assigned to either a hang-pull (n = 9) or jump-squat (n = 9) training group and completed a ten-week, volume-equated, periodized training program. While there was a significant main effect of training for both groups, no statistically significant between-group differences were found (p ≥ 0.17) for any of the dependent variables. However, medium effect sizes in favor of the jump-squat training group were seen in SJ height (d = 0.56) and SJ peak power (d = 0.69). Loaded jumps seem equally effective as weightlifting derivatives for improving lower-body power in experienced athletes. Since loaded jumps require less skill and less coaching expertise than weightlifting, loaded jumps should be considered where coaching complex movements is difficult.

  7. Risk of Transmission of Antimicrobial Resistant Escherichia coli from Commercial Broiler and Free-Range Retail Chicken in India

    Directory of Open Access Journals (Sweden)

    Arif Hussain

    2017-11-01

    Full Text Available Multidrug-resistant Escherichia coli infections are a growing public health concern. This study analyzed the possibility of contamination of commercial poultry meat (broiler and free-range with pathogenic and or multi-resistant E. coli in retail chain poultry meat markets in India. We analyzed 168 E. coli isolates from broiler and free-range retail poultry (meat/ceca sampled over a wide geographical area, for their antimicrobial sensitivity, phylogenetic groupings, virulence determinants, extended-spectrum-β-lactamase (ESBL genotypes, fingerprinting by Enterobacterial Repetitive Intergenic Consensus (ERIC PCR and genetic relatedness to human pathogenic E. coli using whole genome sequencing (WGS. The prevalence rates of ESBL producing E. coli among broiler chicken were: meat 46%; ceca 40%. Whereas, those for free range chicken were: meat 15%; ceca 30%. E. coli from broiler and free-range chicken exhibited varied prevalence rates for multi-drug resistance (meat 68%; ceca 64% and meat 8%; ceca 26%, respectively and extraintestinal pathogenic E. coli (ExPEC contamination (5 and 0%, respectively. WGS analysis confirmed two globally emergent human pathogenic lineages of E. coli, namely the ST131 (H30-Rx subclone and ST117 among our poultry E. coli isolates. These results suggest that commercial poultry meat is not only an indirect public health risk by being a possible carrier of non-pathogenic multi-drug resistant (MDR-E. coli, but could as well be the carrier of human E. coli pathotypes. Further, the free-range chicken appears to carry low risk of contamination with antimicrobial resistant and extraintestinal pathogenic E. coli (ExPEC. Overall, these observations reinforce the understanding that poultry meat in the retail chain could possibly be contaminated by MDR and/or pathogenic E. coli.

  8. Immediate effects of different types of stretching exercises on badminton jump smash.

    Science.gov (United States)

    Jang, Hwi S; Kim, Daeho; Park, Jihong

    2017-04-13

    Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells. Before and after each stretching exercise, subjects performed 20 trials of jump smashes. Dependent measurements were the jump heights during jump smashes, velocities of jump-smashed shuttlecocks, and drop points of jump-smashed shuttlecocks. To test the effects of each stretching exercise, we performed mixed model ANOVAs and calculated between-time effect sizes (ES). Each stretching exercise improved the jump heights during jump smashes (type main effect: F2,75= 1.19, p=0.31; static stretching: 22.1%, pstretching: 30.1%, pstretching: 17.7%, p=0.03, ES: 0.98) and velocities of jump-smashed shuttlecocks (type main effect: F2,75= 2.18, p=0.12; static stretching: 5.7%, p=0.61, ES: 0.39; dynamic stretching: 3.4%, p=0.94, ES: 0.28; resistance dynamic stretching: 6%, p=0.50, ES: 0.66). However, there were no differences among the stretching exercises for any measurement. The drop point of jump-smashed shuttlecocks did not change (interaction: F2,75= 0.88, p=0.42). All stretching exercises improved badminton jump smash performance, but we could not determine the best protocol. Since badminton requires high-speed movement and explosive force, we suggest performing dynamic stretching or resistance dynamic stretching.

  9. Comparison of Antibiotic Resistance and Virulence Factors among Escherichia coli Isolated from Conventional and Free-Range Poultry

    Directory of Open Access Journals (Sweden)

    Vanessa L. Koga

    2015-01-01

    Full Text Available Microbiological contamination in commercial poultry production has caused concerns for human health because of both the presence of pathogenic microorganisms and the increase in antimicrobial resistance in bacterial strains that can cause treatment failure of human infections. The aim of our study was to analyze the profile of antimicrobial resistance and virulence factors of E. coli isolates from chicken carcasses obtained from different farming systems (conventional and free-range poultry. A total of 156 E. coli strains were isolated and characterized for genes encoding virulence factors described in extraintestinal pathogenic E. coli (ExPEC. Antimicrobial susceptibility testing was performed for 15 antimicrobials, and strains were confirmed as extended spectrum of β-lactamases- (ESBLs- producing E. coli by phenotypic and genotypic tests. The results indicated that strains from free-range poultry have fewer virulence factors than strains from conventional poultry. Strains from conventionally raised chickens had a higher frequency of antimicrobial resistance for all antibiotics tested and also exhibited genes encoding ESBL and AmpC, unlike free-range poultry isolates, which did not. Group 2 CTX-M and CIT were the most prevalent ESBL and AmpC genes, respectively. The farming systems of poultries can be related with the frequency of virulence factors and resistance to antimicrobials in bacteria.

  10. Investigation on resistance to drought and efficiency of water usage in two range species, Dactylis glomerata and Eragrostis curvula

    International Nuclear Information System (INIS)

    Jafari, M.; Saiedian, F.; Heydari, H.; Azarnayvand, H.; Farzaneh, Z.

    2000-01-01

    Determination of water efficiency and resistance to drought in range plants are important factors that have essential role in selection of range development methods. As there is not any comprehensive study in resistance to drought, present research was done with selection of two range species. Selected species were two kinds of Gramineae, namely Dactylis glomerata and Eragrostis curvula. Some parameters such as used water, length, width and number of leaves, dry mass of leaves were studies. Obtained results showed that length and width of leaves were not under stress in irrigation periods, but number of leaves, dry mass of leaf and stem decreased under drought stress. Amount of decrease in Eragrostis curvula was less than Dactylis glomerata Increment of irrigation periods, increased root growth rather than stem, but root growth in Dactylis glomerata was more than Eragrostis curvula for production of dry matter, Dactylis glomerata species has less water requirement and higher water usage efficiency in terms of amount of water usage. In terms of resistance to drought, Eragrostis curvula has more resistance rather than Dactylis glomerata because of high water potential and lower witt ing point

  11. Birth of a hydraulic jump

    Science.gov (United States)

    Duchesne, Alexis; Bohr, Tomas; Andersen, Anders

    2017-11-01

    The hydraulic jump, i.e., the sharp transition between a supercritical and a subcritical free-surface flow, has been extensively studied in the past centuries. However, ever since Leonardo da Vinci asked it for the first time, an important question has been left unanswered: How does a hydraulic jump form? We present an experimental and theoretical study of the formation of stationary hydraulic jumps in centimeter wide channels. Two starting situations are considered: The channel is, respectively, empty or filled with liquid, the liquid level being fixed by the wetting properties and the boundary conditions. We then change the flow-rate abruptly from zero to a constant value. In an empty channel, we observe the formation of a stationary hydraulic jump in a two-stage process: First, the channel fills by the advancing liquid front, which undergoes a transition from supercritical to subcritical at some position in the channel. Later the influence of the downstream boundary conditions makes the jump move slowly upstream to its final position. In the pre-filled channel, the hydraulic jump forms at the injector edge and then moves downstream to its final position.

  12. Sex Differences in Countermovement Jump Phase Characteristics

    Directory of Open Access Journals (Sweden)

    John J. McMahon

    2017-01-01

    Full Text Available The countermovement jump (CMJ is commonly used to explore sex differences in neuromuscular function, but previous studies have only reported gross CMJ measures or have partly examined CMJ phase characteristics. The purpose of this study was to explore differences in CMJ phase characteristics between male and female athletes by comparing the force-, power-, velocity-, and displacement-time curves throughout the entire CMJ, in addition to gross measures. Fourteen men and fourteen women performed three CMJs on a force platform from which a range of kinetic and kinematic variables were calculated via forward dynamics. Jump height (JH, reactive strength index modified, relative peak concentric power, and eccentric and concentric displacement, velocity, and relative impulse were all greater for men (g = 0.58–1.79. Relative force-time curves were similar between sexes, but relative power-, velocity-, and displacement-time curves were greater for men at 90%–95% (immediately before and after peak power, 47%–54% (start of eccentric phase and 85%–100% (latter half of concentric phase, and 65%–87% (bottom of countermovement and initial concentric phase of normalized jump time, respectively. The CMJ distinguished between sexes, with men demonstrating greater JH through applying a larger concentric impulse and, thus, achieving greater velocity throughout most of the concentric phase, including take-off.

  13. Study of atomic jumps in quasi-crystals

    International Nuclear Information System (INIS)

    Lyonnard, S.

    1997-01-01

    The terminology phason used in quasicrystals to refer to atomic jumps. The study of the hopping process is important for the understanding of many basic issues in quasi-crystallography: structure, stability, diffusion, phase transitions between quasicrystals and approximants, mechanical properties. Quasi-elastic neutron scattering allows to find the characteristics of each elementary jump: chemical species involves, relaxation times, activation energies, jump distances and orientations. We performed a series of experiments in the perfect icosahedral phases AlFeCu and AlMnPd, on both powders and single domain samples, using time-of-flight, backscattering and triple axis spectrometers. We evidenced the existence of very fast phason hopping, and studied about ten different atomic jumps. An unusual temperature dependence has been found systematically: each process is assisted by a thermally activated mechanism. The assistance process has to be determined case by case, but the more plausible explanation invokes assistance by phonons or phason clouds. Moreover, the dependence of the quasi elastic signal as a function of the momentum transfer shows that the jumps are local and do not give rise to any long-range diffusion. Phason hopping mainly corresponds to the atom moving forwards and backwards between two energetically equivalent sites. Finally, we have been able to show that the jumps occur along the various quasi-crystalline symmetry axes. (author)

  14. PMMA-based resists for a spectral range near 13 nm

    CERN Document Server

    Bulgakova, S A; Luchin, V I; Mazanova, L M; Molodnjakov, S A; Salashchenko, N N

    2000-01-01

    A number of poly(meth)acrylates positive resists of various chemical structures were synthesized and the sensitivity of 0.2 mu m resists films to soft X-ray radiation of a laser plasma source at a wavelength of 13 nm was investigated. We found that the sensitivity of methylmethacrylate (MMA) copolymers depending on the nature of comonomers changes within the limits of 12.3-1.7 mJ/cm sup 2 in a combination with the contrast gamma=5.4-1.0. This sensitivity is higher than that of PMMA, which changes from 12 to 45 mJ/cm sup 2 at the contrast gamma=2.6-8.0 depending on the developer composition of methylethylketone (MEK)/isopropyl alcohol (IPA).

  15. PMMA-based resists for a spectral range near 13 nm

    International Nuclear Information System (INIS)

    Bulgakova, S.A.; Lopatin, A.Ya.; Luchin, V.I.; Mazanova, L.M.; Molodnjakov, S.A.; Salashchenko, N.N.

    2000-01-01

    A number of poly(meth)acrylates positive resists of various chemical structures were synthesized and the sensitivity of 0.2 μm resists films to soft X-ray radiation of a laser plasma source at a wavelength of 13 nm was investigated. We found that the sensitivity of methylmethacrylate (MMA) copolymers depending on the nature of comonomers changes within the limits of 12.3-1.7 mJ/cm 2 in a combination with the contrast γ=5.4-1.0. This sensitivity is higher than that of PMMA, which changes from 12 to 45 mJ/cm 2 at the contrast γ=2.6-8.0 depending on the developer composition of methylethylketone (MEK)/isopropyl alcohol (IPA)

  16. Thermal properties of Nb from acoustic and electrical resistivity measurements in the temperature range 60--340 K

    International Nuclear Information System (INIS)

    Cannelli, G.; Cannelli, G.B.

    1976-01-01

    The thermal diffusivity and the relative difference in molar heat capacities, (C/subp/-C/subv/)/C/subv/, of polycrystalline niobium have been derived from acoustic measurements in the temperature range 60--340 K. The electrical resistivity has also been measured from 8 to 340 K; 0.833 μΩ cm, 18.7, and 9.25 K being the values of residual resistivity rho 0 , resistance ratio rho (300 K)/rho 0 , and superconducting transition temperature, respectively. The thermal conductivity, Lorenz ratio, and molar heat capacity at constant volume have been calculated for the temperature range 60--340 K, using present values of thermal diffusivity, electrical resistivity, and literature values of specific heat C/subp/. A shallow maximum in the derived thermal conductivity curve is observed around 180 K where the Lorenz ratio assumes the maximum value 3.15x10 -8 W Ω K -2 . It is suggested that the thermal conductivity maximum may originate in the phonon contribution

  17. Choice of jumping strategy in two standard jumps, squat and countermovement jump--effect of training background or inherited preference?

    DEFF Research Database (Denmark)

    Ravn, Susanne; Voigt, M; Simonsen, Erik Bruun

    1999-01-01

    Six male subjects, three professional ballet dancers and three elite volleyball players, performed maximal vertical jumps from 1) a static preparatory position (squat jump), 2) starting with a countermovement (countermovement jump) and 3) a specific jump for ballet and for volleyball, respectively...... was performed with a sequential strategy and the ballet jump was performed with a simultaneous strategy. In the two standard jumps, the choice of strategy was individual and not related to training background. This was additionally confirmed in a test of seven ballet dancers and seven volleyball players....

  18. Geomorphic implications of resistant bedrock in the 'uniform' sandstone beds of the Tyee Formation, Oregon Coast Range

    Science.gov (United States)

    Marshall, J. A.; Roering, J. J.; Dorsey, R. J.

    2011-12-01

    Differences in rock properties are reflected in landscape morphology and all else equal, harder rock should produce steeper hillslopes. While this concept is oft-stated, it is seldom characterized. In the humid, soil-mantled mountainous landscape of the Oregon Coast Range (OCR), steep hillslopes are sculpted in rhythmically bedded sandstones of the Eocene Tyee Formation where subtle variations in rock properties appear to have profound geomorphic implications. Numerous resistant beds appear unfractured and impervious to soil production mechanisms such as tree root activity and mountain beaver burrowing. Here we present observations from the field, thin section petrology, rock mechanics, and airborne lidar to characterize minor grain-scale differences in rock properties and their influence on rock strength and fracture density and thus hillslope processes and morphology. In Franklin Creek watershed, bands of cliff-forming resistant sandstone crop out in ~1-10m thick swaths. These cliff-forming bands are absent in the adjacent Harvey watershed due to the local structural setting. Harvey watershed is characterized by 'classic' OCR topography -repeating ridge and valley sequences, while Franklin watershed exhibits hanging valleys and changes in slope and curvature above the cliff-forming beds. Although calcite-cemented sandstone beds are reported in the literature for the Tyee Fm, we find no evidence for calcite in the resistant sandstone beds. Instead, preliminary petrographic analysis suggests that diagenetic clay rims in the resistant rock types may account for their higher strength. Preliminary point load and indirect tensile strength tests comparing 'typical' and 'resistant' beds of the Tyee Formation show a significant difference, with indirect tensile strength measurements of 0.83 ± 0.1 MPa for typical rock and 2.06 ± 0.7 MPa for the resistant rock type. Using airborne lidar data we explore how these resistant beds modulate topography. Soil production in much

  19. How far can Tarzan jump?

    Science.gov (United States)

    Shima, Hiroyuki

    2012-11-01

    The tree-based rope swing is a popular recreational facility, often installed in outdoor areas. Hanging from a rope, users drop from a high platform and then swing at great speed like ‘Tarzan’, finally jumping ahead to land on the ground. The question naturally arises, how far can Tarzan jump using the swing? In this paper, I present an introductory analysis of the mechanics of the Tarzan swing, a large pendulum-like swing with Tarzan himself attached as weight. This enables determination of how much further forward Tarzan can jump using a given swing apparatus. The discussion is based on elementary mechanics and is, therefore, expected to provide rich opportunities for investigations using analytic and numerical methods.

  20. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    International Nuclear Information System (INIS)

    Vecchiola, Aymeric; Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric; Delprat, Sophie; Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard; Tatay, Sergio; Geffroy, Bernard

    2016-01-01

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  1. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    Energy Technology Data Exchange (ETDEWEB)

    Vecchiola, Aymeric [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Concept Scientific Instruments, ZA de Courtaboeuf, 2 rue de la Terre de Feu, 91940 Les Ulis (France); Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric, E-mail: frederic.houze@geeps.centralesupelec.fr [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Delprat, Sophie [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); UPMC, Université Paris 06, 4 place Jussieu, 75005 Paris (France); Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Tatay, Sergio [Molecular Science Institute, University of Valencia, 46980 Paterna (Spain); Geffroy, Bernard [Lab. Physique des Interfaces et Couches minces (PICM), UMR 7647 CNRS-École polytechnique, 91128 Palaiseau (France); Lab. d' Innovation en Chimie des Surfaces et Nanosciences (LICSEN), NIMBE UMR 3685 CNRS-CEA Saclay, 91191 Gif-sur-Yvette (France); and others

    2016-06-13

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  2. How far can Tarzan jump?

    OpenAIRE

    Shima, Hiroyuki

    2012-01-01

    The tree-based rope swing is a popular recreation facility, often installed in outdoor areas, giving pleasure to thrill-seekers. In the setting, one drops down from a high platform, hanging from a rope, then swings at a great speed like "Tarzan", and finally jumps ahead to land on the ground. The question now arises: How far can Tarzan jump by the swing? In this article, I present an introductory analysis of the Tarzan swing mechanics, a big pendulum-like swing with Tarzan himself attached as...

  3. Scaling of interfacial jump conditions

    International Nuclear Information System (INIS)

    Quezada G, S.; Vazquez R, A.; Espinosa P, G.

    2015-09-01

    To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)

  4. Vaccination with Trypanosoma rangeli induces resistance of guinea pigs to virulent Trypanosoma cruzi.

    Science.gov (United States)

    Basso, B; Moretti, E; Fretes, R

    2014-01-15

    Chagas' disease, endemic in Latin America, is spread in natural environments through animal reservoirs, including marsupials, mice and guinea pigs. Farms breeding guinea pigs for food are located in some Latin-American countries with consequent risk of digestive infection. The aim of this work was to study the effect of vaccination with Trypanosoma rangeli in guinea pigs challenged with Trypanosoma cruzi. Animals were vaccinated with fixated epimastigotes of T. rangeli, emulsified with saponin. Controls received only PBS. Before being challenged with T. cruzi, parasitemia, survival rates and histological studies were performed. The vaccinated guinea pigs revealed significantly lower parasitemia than controls (pguinea pigs and dogs. The development of vaccines for use in animals, like domestic dogs and guinea pigs in captivity, opens up new opportunities for preventive tools, and could reduce the risk of infection with T. cruzi in the community. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. ASSESSMENT OF RANGES OF POSSIBLE CHANGE OF TEMPORARY RESISTANCE OF CAST IRON WITH LAMELLAR AND FLAKED GRAPHITE ON THEIR HARDNESS

    Directory of Open Access Journals (Sweden)

    S. G. Sandomirskii

    2017-01-01

    Full Text Available The analysis of ranges of possible change of temporary resistance of sB of castings from ductile and gray cast iron is carried out. The analytical description of ranges of change of sВ depending on casting BH hardness is developed. It is shown that the range of change of sВ of pig-iron castings, wider in comparison with steel, with the measured hardness of BH is caused variations of forms and the amount of graphite inclusions at the considered classes of cast iron and influence of thickness of a wall of casting from gray cast iron on dependence of sВ (HB. The result is intended for determination of the guaranteed casting size sВ without her destruction, when there is no information on sВ of check test pieces.

  6. Free-Ranging Frigates (Fregata magnificens of the Southeast Coast of Brazil Harbor Extraintestinal Pathogenic Escherichia coli Resistant to Antimicrobials.

    Directory of Open Access Journals (Sweden)

    Juliana Yuri Saviolli

    Full Text Available Seabirds may be responsible for the spread of pathogenic/resistant organisms over great distances, playing a relevant role within the context of the One World, One Health concept. Diarrheagenic E. coli strains, known as STEC (shiga toxin-producing E. coli, and the extraintestinal pathogenic E. coli (ExPEC and the subpathotype APEC, are among the E. coli pathotypes with zoonotic potential associated with the birds. In order to identify health threats carried by frigates and to evaluate the anthropic influence on the southern coast of Brazil, the aim of this work was to characterize E. coli isolated from free-ranging frigates in relation to virulence genotypes, serotypes, phylogenetic groups and antimicrobial resistance. Cloacal and choanal swabs were sampled from 38 Fregata magnificens from two oceanic islands and one rescue center. Forty-three E. coli strains were recovered from 33 out of the 38 birds (86.8%; 88.4% of strains showed some of the virulence genes (VGs searched, 48.8% contained three or more VGs. None of the strains presented VGs related to EPEC/STEC. Some of the isolates showed virulence genotypes, phylogenetic groups and serotypes of classical human ExPEC or APEC (O2:H7, O1:H6, ONT:H7, O25:H4. Regarding antimicrobial susceptibility, 62.8% showed resistance, and 11.6% (5/43 were multidrug-resistant. The E. coli present in the intestines of the frigates may reflect the environmental human impact on southeast coast of Brazil; they may also represent an unexplored threat for seabird species, especially considering the overlap of pathogenic potential and antimicrobial resistance present in these strains.

  7. Doppler ultrasound velocities and resistive indexes immediately after pediatric liver transplantation: normal ranges and predictors of failure.

    Science.gov (United States)

    Jamieson, Lucy H; Arys, Bo; Low, Gavin; Bhargava, Ravi; Kumbla, Surekha; Jaremko, Jacob L

    2014-07-01

    We sought to determine the ranges of Doppler ultrasound findings immediately after pediatric liver transplantation that are associated with successful outcomes or postoperative complications. This study included consecutive children who underwent Doppler ultrasound less than 48 hours after liver transplantation from 2001 to 2011. Operative reports and clinical outcome data were recorded. We had 110 patients (54% girls) with mean age at transplantation of 2.9 years (median, 1.3 years; range, 0-14 years) and a median follow-up interval of 3.5 years. Two pediatric radiologists reviewed ultrasound images in consensus. We computed descriptive statistics, interindex correlations, and analysis of variance. Twenty-four of 110 patients had a vascular complication, most commonly hepatic arterial thrombosis (seven patients). Compared with published adult normal values, normal pediatric Doppler parameters at postoperative day 1 trended toward higher normal velocities and resistive indexes (up to 0.95). Absent or low-velocity common hepatic artery flow less than 50 cm/s or a common hepatic artery resistive index less than 0.50 were significantly associated with hepatic artery thrombosis, whereas absent or low-velocity portal venous flow less than 30 cm/s or low-velocity hepatic venous flow less than 25 cm/s were significantly associated with vascular complications and a monotonic hepatic venous waveform was significantly associated with venous complications. Flow in a pediatric liver on the first day after transplantation is normally hyperdynamic, especially in the youngest transplant recipients, and, as a result, low velocities or resistive indexes are particularly concerning for complications. The pediatric-specific ranges of expected posttransplantation Doppler ultrasound findings presented in this article should assist in identifying normal variation and potentially life-threatening complications.

  8. The identification of price jumps

    Czech Academy of Sciences Publication Activity Database

    Hanousek, Jan; Kočenda, Evžen; Novotný, Jan

    2012-01-01

    Roč. 18, č. 1 (2012), s. 53-77 ISSN 0929-9629 R&D Projects: GA ČR(CZ) GAP403/11/0020; GA ČR(CZ) GBP402/12/G097 Institutional support: PRVOUK-P23 Keywords : price jumps * non-parametric testing * financial econometrics Subject RIV: AH - Economics

  9. Regime Jumps in Electricity Prices

    NARCIS (Netherlands)

    R. Huisman (Ronald); R.J. Mahieu (Ronald)

    2001-01-01

    textabstractElectricity prices are known to be very volatile and subject to frequent jumps due to system breakdown, demand shocks, and inelastic supply. As many international electricity markets are in some state of deregulation, more and more participants in these markets are exposed to these

  10. Strawberry Shortcake and Other Jumping Rope Ideas.

    Science.gov (United States)

    Adams, Polly K.; Taylor, Michaell K.

    Information, guidelines, and activities for jumping rope are given. A short history of jumping rope explains how it evolved from a spring ritual for men to a play activity involving mostly young girls. Physical and cultural reasons are given as to why jumping rope has been more a sport for girls than for boys. Research studies are noted which show…

  11. Some remarks on the time of flight and range of a projectile in a linear resisting medium

    Directory of Open Access Journals (Sweden)

    S. M. Stewart

    2011-01-01

    Full Text Available In view of the recent work by Karkantzakos [Journal of Engineering Science and Technology Review 2 (2009 76–81], anumber of remarks highlighting the connection between the Lambert W function and the time of flight and range of a projectilemoving in a resisting medium where the retarding force acting on the projectile is proportional to its velocity are made.In particular, we show how each of these quantities can be expressed in closed form in terms of the Lambert W function andindicate how the analysis of the motion becomes greatly simplified by its introduction.

  12. Study of Proper Time Range for Current Flow to Resistance Spot Welding Inspected by Mechanical Property and Metallurgy Testing

    International Nuclear Information System (INIS)

    Pearsura, Prachya

    2007-08-01

    Full text: This research used the mechanical property and metallurgy testing to identify the proper time range for current flow. The specimen tested was 1 mm thick mild steel. The welded specimens were tested by Tensile Shear testing following JIS Z 3136: 1999 and Macro Structure testing follow by JIS Z 3139: 1978. Subsequently, the results from analyzing were compared with standard JIS Z 3140. The results show that the suitable current flow is 8 to 10 cycles. This technique can be applied to monitor the process and the quality of resistance spot welding

  13. Creating an immersive virtual reality application for ski jumping

    OpenAIRE

    Staurset, Emil Moltu

    2015-01-01

    Virtual reality(VR) has been successfully applied to a broad range of training domains. VR provides an opportunity to train in a safe and controlled environment, with support for accurate performance measurement. In this report I present a prototype of a VR application for ski jumping. The goal for this project is to explore if such an application can be used to teach the basics of ski jumping, and if it can be used as a training tool for athletes. The development process is thoroughly descr...

  14. Mesopause Jumps: Observations and Explanation

    Science.gov (United States)

    Luebken, F. J.; Becker, E.; Höffner, J.; Viehl, T. P.; Latteck, R.

    2017-12-01

    Recent high resolution temperature measurements by resonance lidar at Davis (69°S) occasionally showed a sudden mesopause altitude increase by 5km and an associated mesopause temperature decrease by 10K. We present further observations which are closely related to this `mesopause jump', namely the increase of mean height of polar mesospheric summer echoes (PMSE) observed by a VHF radar, very strong westward winds in the upper mesosphere measured by an MF radar, and relatively large eastward winds in the stratosphere taken from reanalysis. We compare to similar observations in the Northern Hemisphere, namely at ALOMAR (69°N) where such mesopause jumps have never been observed. We present a detailed explanation of mesopause jumps. They occur only when stratospheric winds are moderately eastward and mesospheric winds are very large (westward). Under these conditions, gravity waves with comparatively large eastward phase speeds can pass the stratosphere and propagate to the lower thermosphere because their vertical wavelengths in the mesosphere are rather large which implies reduced dynamical stability. When finally breaking in the lower thermosphere, these waves drive an enhanced residual circulation that causes a cold and high-altitude mesopause. The conditions for a mesopause jump occur only in the Southern Hemisphere (SH) and are associated with the late breakdown of the polar vortex.Mesopause jumps are primarily, but not only, observed prior and close to solstice. We also show that during the onset of PMSE in the SH, stratospheric zonal winds are still eastward (up to 30m/s), and that the onset is not closely related to the transition of the stratospheric circulation.

  15. Mesopause jumps at Antarctic latitudes

    Science.gov (United States)

    Lübken, Franz-Josef; Höffner, Josef; Becker, Erich; Latteck, Ralph; Murphy, Damian

    2016-04-01

    Recent high resolution temperature measurements by resonance lidar at Davis (69°S) occasionally showed a sudden mesopause altitude increase by ˜5 km and an associated mesopause temperature decrease by ˜10 K. We present further observations which are closely related to this 'mesopause jump', namely the increase of mean height of polar mesospheric summer echoes (PMSE) observed by a VHF radar, very strong westward winds in the upper mesosphere measured by an MF radar, and relatively large eastward winds in the stratosphere taken from reanalysis. We compare to similar observations in the Northern Hemisphere, namely at ALOMAR (69°N) where such mesopause jumps have never been observed. We present a detailed explanation of mesopause jumps. They occur only when stratospheric winds are moderately eastward and mesospheric winds are very large (westward). Under these conditions, gravity waves with comparatively large eastward phase Speeds can pass the stratosphere and propagate to the lower thermosphere because their vertical wavelengths in the mesosphere are rather large which implies reduced dynamical stability. When finally breaking in the lower thermosphere, these waves drive an enhanced residual circulation that causes a cold and high-altitude mesopause. The conditions for a mesopause jump occur only in the Southern Hemisphere (SH) and are associated with the late breakdown of the polar vortex. Mesopause jumps are primarily, but not only, observed prior and close to solstice. We also show that during the onset of PMSE in the SH, stratospheric zonal winds are still eastward (up to 30 m/s), and that the onset is not closely related to the Transition of the stratospheric circulation.

  16. Insulation resistance abnormal condition detector for a local power range monitor

    International Nuclear Information System (INIS)

    Akiyama, Takao; Mizuno, Katsuhiro; Kai, Takaaki.

    1976-01-01

    Object: To permit determination of abnormal condition by a number of local power range monitors (LPRM ) to be quickly made through estimation of the leakage current value by precisely estimating the ratio between the true rate of change in neutron flux and true change in the neutron flux by making use of the fact that the status of the neutron distribution does not widely change with a change of the core flow rate for a short period of time. Structure: While carrying out power control according to the core flow rate, detection values from LPRM which are disposed in a three-dimensional fashion within the reactor core are indicated on an indicator. The average value of rates of change in the indicated values for a group of LPRM under substantially the same fluid dynamic condition as that for each LPRM is determined by measuring the ratio before and after the alteration of the power of the indicated value. Further, the estimation of leakage current is determined by using the ratio of the indicated value, average value thereof and amplifier gain of each LPRM. When the estimation leakage current exceeds a prescribed value, the corresponding LPRM is determined to be defective. (Moriyama, K.)

  17. AGS tune jump power supply design and test

    Energy Technology Data Exchange (ETDEWEB)

    Mi, J.; Glenn, J.W.; Huang, H.; Marneris, I.; Rosas, P.; Sandberg, J.; Tan, Y.; Zhang, W.

    2011-03-28

    A horizontal tune jump system has been installed to overcome the horizontal intrinsic spin resonances, which requires jumping the horizontal tune 0.04 units 82 times, 41 up and 41 down. Two quadruple magnets have been installed in AGS ring to perform this. The pulsed magnet current ranges from about 140A near injection to about 1400A later. The current pulse rise and fall time are around 100uS and flat tops time is around 4mS. These quadruples have separated supplies. This tune jump pulse power supply employees all semiconductor parts as well as the main switches. During dummy load and magnet testing, the test results showed that the power supply could meet the specification. This article will describe some details of power supply simulation, design and testing. Some test waveforms and pictures are presented in this paper.

  18. Evaluation of corrosion resistance of implant-use Ti-Zr binary alloys with a range of compositions.

    Science.gov (United States)

    Akimoto, Teisuke; Ueno, Takeshi; Tsutsumi, Yusuke; Doi, Hisashi; Hanawa, Takao; Wakabayashi, Noriyuki

    2018-01-01

    Although titanium-zirconium (Ti-Zr) alloy has been adopted for clinical applications, the ideal proportion of Zr in the alloy has not been identified. In this study, we investigated the biocompatibility of Ti-Zr alloy by evaluating its corrosion resistance to better understand whether there is an optimal range or value of Zr proportion in the alloy. We prepared pure Ti, Ti-30Zr, Ti-50Zr, Ti-70Zr, and pure Zr (mol% of Zr) samples and subjected them to anodic polarization and immersion tests in a lactic acid + sodium chloride (NaCl) solution and artificial saliva. We observed pitting corrosion in the Ti-70Zr and Zr after exposure to both solutions. After the immersion test, we found that pure Ti exhibited the greatest degree of dissolution in the lactic acid + NaCl solution, with the addition of Zr dramatically reducing Ti ion dissolution, with the reduction ultimately exceeding 90% in the case of the Ti-30Zr. Hence, although the localized corrosion resistance under severe conditions was compromised when the Zr content was more than 70%, metal ion release reduced owing to Zr addition and the corresponding formation of a stable passive layer. The results suggest that Ti-30Zr or a Zr proportion of less than 50% would offer an ideal level of corrosion resistance for clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 73-79, 2018. © 2016 Wiley Periodicals, Inc.

  19. Kinetic and kinematic compensations in amputee vertical jumping.

    Science.gov (United States)

    Schoeman, Marlene; Diss, Ceri E; Strike, Siobhan C

    2012-08-01

    A unilateral transtibial amputation causes a disruption to the musculoskeletal system, which results in asymmetrical biomechanics. The current study aimed to assess the movement asymmetry and compensations that occur as a consequence of an amputation when performing a countermovement vertical jump. Six unilateral transtibial amputees and 10 able-bodied (AB) participants completed 10 maximal vertical jumps, and the highest jump was analyzed further. Three-dimensional lower limb kinematics and normalized (body mass) kinetic variables were quantified for the intact and prosthetic sides. Symmetry was assessed through the symmetry index (SI) for each individual and statistically using the Mann-Whitney U test between the intact and prosthetic sides for the amputee group. A descriptive analysis between the amputee and AB participants was conducted to explore the mechanisms of amputee jumping. The amputee jump height ranged from 0.09 to 0.24 m. In the countermovement, all ankle variables were asymmetrical (SI > 10%) and statistically different (p amputees. At the knee and hip, there was no statistical difference between the intact and prosthetic sides range of motion, although there was evidence of individual asymmetry. The knees remained more extended compared with the AB participants to prevent collapse. In propulsion, the prosthesis did not contribute to the work done and the ankle variables were asymmetrical (p < .05). The knee and hip variables were not statistically different between the intact and prosthetic sides, although there was evidence of functional asymmetry and the contribution tended to be greater on the intact compared with the prosthetic side. The lack of kinetic involvement of the prosthetic ankle and both knees due to the limitation of the prosthesis and the altered musculoskeletal mechanics of the joints were the reason for the reduced height jumped.

  20. Thomson's Jumping Ring Over a Long Coil

    Science.gov (United States)

    Jeffery, Rondo N.; Amiri, Farhang

    2018-03-01

    The classic jumping ring apparatus consists of a coil with an iron core that extends out of the coil. A copper or aluminum ring placed over the iron core jumps upward when AC power is applied to the coil. In this paper we will examine a modified design of the jumping ring apparatus, called the "long-coil design." It allows the ring to jump upward or downward, depending on the starting position of the ring. These features shed significant light on the study of the force that causes the ring to jump.

  1. Covariant jump conditions in electromagnetism

    International Nuclear Information System (INIS)

    Itin, Yakov

    2012-01-01

    A generally covariant four-dimensional representation of Maxwell’s electrodynamics in a generic material medium can be achieved straightforwardly in the metric-free formulation of electromagnetism. In this setup, the electromagnetic phenomena are described by two tensor fields, which satisfy Maxwell’s equations. A generic tensorial constitutive relation between these fields is an independent ingredient of the theory. By use of different constitutive relations (local and non-local, linear and non-linear, etc.), a wide area of applications can be covered. In the current paper, we present the jump conditions for the fields and for the energy–momentum tensor on an arbitrarily moving surface between two media. From the differential and integral Maxwell equations, we derive the covariant boundary conditions, which are independent of any metric and connection. These conditions include the covariantly defined surface current and are applicable to an arbitrarily moving smooth curved boundary surface. As an application of the presented jump formulas, we derive a Lorentzian type metric as a condition for existence of the wave front in isotropic media. This result holds for ordinary materials as well as for metamaterials with negative material constants. - Highlights: ► Covariant metric-free jump conditions for the electromagnetic field are derived. ► Covariantly defined surface current is considered. ► Lorentzian type metric from existence of the wave front in isotropic media. ► The result holds for ordinary materials as well as for metamaterials.

  2. A Very Low Dark Current Temperature-Resistant, Wide Dynamic Range, Complementary Metal Oxide Semiconductor Image Sensor

    Science.gov (United States)

    Mizobuchi, Koichi; Adachi, Satoru; Tejada, Jose; Oshikubo, Hiromichi; Akahane, Nana; Sugawa, Shigetoshi

    2008-07-01

    A very low dark current (VLDC) temperature-resistant approach which best suits a wide dynamic range (WDR) complementary metal oxide semiconductor (CMOS) image sensor with a lateral over-flow integration capacitor (LOFIC) has been developed. By implementing a low electric field photodiode without a trade-off of full well-capacity, reduced plasma damage, re-crystallization, and termination of silicon-silicon dioxide interface states in the front end of line and back end of line (FEOL and BEOL) in a 0.18 µm, two polycrystalline silicon, three metal (2P3M) process, the dark current is reduced to 11 e-/s/pixel (0.35 e-/s/µm2: pixel area normalized) at 60 °C, which is the lowest value ever reported. For further robustness at low and high temperatures, 1/3-in., 5.6-µm pitch, 800×600 pixel sensor chips with low noise readout circuits designed for a signal and noise hold circuit and a programmable gain amplifier (PGA) have also been deposited with an inorganic cap layer on a micro-lens and covered with a metal hermetically sealed package assembly. Image sensing performance results in 2.4 e-rms temporal noise and 100 dB dynamic range (DR) with 237 ke- full well-capacity. The operating temperature range is extended from -40 to 85 °C while retaining good image quality.

  3. Genetic structure of Bemisia tabaci Med populations from home-range countries, inferred by nuclear and cytoplasmic markers : impact on the distribution of the insecticide resistance genes

    OpenAIRE

    Gauthier, Nathalie; Clouet, C.; Perrakis, A.; Kapantaidaki, D.; Peterschmitt, M.; Tsagkarakou, A.

    2014-01-01

    BACKGROUND: Insecticide resistance management in Bemisia tabaci is one of the main issues facing agricultural production today. An extensive survey was undertaken in five Mediterranean countries to examine the resistance status of Med B. tabaci species in its range of geographic origin and the relationship between population genetic structure and the distribution of resistance genes. The investigation combined molecular diagnostic tests, sequence and microsatellite polymorphism studies and mo...

  4. Resistance Upset Welding of ODS Steel Fuel Claddings—Evaluation of a Process Parameter Range Based on Metallurgical Observations

    Directory of Open Access Journals (Sweden)

    Fabien Corpace

    2017-08-01

    Full Text Available Resistance upset welding is successfully applied to Oxide Dispersion Strengthened (ODS steel fuel cladding. Due to the strong correlation between the mechanical properties and the microstructure of the ODS steel, this study focuses on the consequences of the welding process on the metallurgical state of the PM2000 ODS steel. A range of process parameters is identified to achieve operative welding. Characterizations of the microstructure are correlated to measurements recorded during the welding process. The thinness of the clad is responsible for a thermal unbalance, leading to a higher temperature reached. Its deformation is important and may lead to a lack of joining between the faying surfaces located on the outer part of the join which can be avoided by increasing the dissipated energy or by limiting the clad stick-out. The deformation and the temperature reached trigger a recrystallization phenomenon in the welded area, usually combined with a modification of the yttrium dispersion, i.e., oxide dispersion, which can damage the long-life resistance of the fuel cladding. The process parameters are optimized to limit the deformation of the clad, preventing the compactness defect and the modification of the nanoscale oxide dispersion.

  5. MULTI-DRUG RESISTANCE PATTERNS OF ENTERIC BACTERIA IN TWO POPULATIONS OF FREE-RANGING EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA).

    Science.gov (United States)

    Rasmussen, Cari; Allender, Matthew C; Phillips, Christopher A; Byrd, John; Lloyd, Terrell; Maddox, Carol

    2017-09-01

    Gram-negative isolates (n = 84) from 71% of free-ranging Eastern box turtles (Terrapene carolina carolina) in Illinois and Tennessee, United States, demonstrated resistance to at least one antibiotic while 30% of isolates demonstrated resistance to two or more antibiotics. Resistance was observed against cefoxitin, amoxicillin-clavulanic acid, cefazolin, ampicillin, ticarcillin, cefovecin, and ceftiofur. Gram-positive bacteria were isolated from 49 turtles, and all were observed to be resistant to two or more antibiotics. Gram-positive isolate resistance was observed to penicillin, cefoxitin, oxacillin, clindamycin, amikacin, enrofloxacin, cefovecin, ceftiofur, cefazolin, marbofloxacin, gentamicin, erythromycin, trimethoprim-sulfamethoxazole, and chloramphenicol. Health parameters including packed cell volume, total white blood cell count (WBC), total solids (TS), and weight were not significantly different based on antibiotic resistance patterns; however, decreasing WBC and TS were observed when the number of antibiotic-resistant detections in Gram-positive bacteria increased.

  6. Upper Limb Static-Stretching Protocol Decreases Maximal Concentric Jump Performance

    Directory of Open Access Journals (Sweden)

    Paulo H. Marchetti

    2014-12-01

    Full Text Available The purpose of the present study was to evaluate the acute effects of an upper limb static-stretching (SS protocol on the maximal concentric jump performance. We recruited 25 young healthy, male, resistance trained individuals (stretched group, n = 15 and control group, n = 10 in this study. The randomized between group experimental protocol consisted of a three trials of maximal concentric jump task, before and after a SS of the upper limb. Vertical ground reaction forces (vGRF and surface electromyography (sEMG of both gastrocnemius lateralis (GL and vastus lateralis (VL were acquired. An extensive SS was employed consisting of ten stretches of 30 seconds, with 15 seconds of rest, and 70-90% of the point of discomfort (POD. ANOVA (2x2 (group x condition was used for shoulder joint range of motion (ROM, vGRF and sEMG. A significant interaction for passive ROM of the shoulder joint revealed significant increases between pre- and post-SS protocol (p < 0.001. A significant interaction demonstrated decreased peak force and an increased peak propulsion duration between pre- and post-stretching only for stretch group (p = 0.021, and p = 0.024, respectively. There was a significant main effect between groups (stretch and control for peak force for control group (p = 0.045. Regarding sEMG variables, there were no significant differences between groups (control versus stretched or condition (pre-stretching versus post-stretching for the peak amplitude of RMS and IEMG for both muscles (VL and GL. In conclusion, an acute extensive SS can increase the shoulder ROM, and negatively affect both the propulsion duration and peak force of the maximal concentric jump, without providing significant changes in muscle activation.

  7. Spatially constrained propulsion in jumping archer fish

    Science.gov (United States)

    Mendelson, Leah; Techet, Alexandra

    2016-11-01

    Archer fish jump multiple body lengths out of the water for prey capture with impressive accuracy. Their remarkable aim is facilitated by jumping from a stationary position directly below the free surface. As a result of this starting position, rapid acceleration to a velocity sufficient for reaching the target occurs with only a body length to travel before the fish leaves the water. Three-dimensional measurements of jumping kinematics and volumetric velocimetry using Synthetic Aperture PIV highlight multiple strategies for such spatially constrained acceleration. Archer fish rapidly extend fins at jump onset to increase added mass forces and modulate their swimming kinematics to minimize wasted energy when the body is partially out of the water. Volumetric measurements also enable assessment of efficiency during a jump, which is crucial to understanding jumping's role as an energetically viable hunting strategy for the fish.

  8. Avaliação da resistência de força explosiva em voleibolistas através de testes de saltos verticais Assessment of explosive strength-endurance in volleyball players through vertical jumping test

    Directory of Open Access Journals (Sweden)

    Jefferson Eduardo Hespanhol

    2007-06-01

    Full Text Available O propósito deste estudo foi verificar a existência de diferenças entre o teste de salto vertical com natureza contínua de 60 segundos (TSVC e o teste de salto vertical com natureza intermitente de quatro séries de 15 segundos (TSVI. Os dados foram obtidos através de amostra composta por 10 voleibolistas do sexo masculino (19,01 ± 1,36 anos; 191,5 ± 5,36cm; e 81,74 ± 7,45kg, todos com participação voluntária. As variáveis estudadas foram: as estimativas do pico de potência (PP, potência média (PM e o índice de fadiga (IF. O desempenho estimado através dos testes TSVC, com duração de 60 segundos, e o TSVI foi determinado em quatro séries de 15 segundos, com 10 segundos de recuperação entre cada série. Os dados foram determinados através da estatística descritiva e do teste de Wilcoxon; o nível de significância utilizado foi de p The aim of this study was to verify the differences between the continuous jump test of 60 seconds (CJ60 sec and the intermittent jump test of 4 sets of 15 seconds (IJ4x15 sec. The sample was composed of 10 male volleyball players with 19.01 ± 1.36 years, 191.5 ± 5.36 cm height and 81.74 ± 7.45 of body mass, who participated in this research as volunteers. The variables studied were estimated as the peak power (PP, mean power (MP and fatigue index (FI. These performances were measured through tests of vertical jump with duration the 60 seconds and with the performance of 4 sets of 15 seconds with 10 seconds of recovery between the sets. The data were analyzed through descriptive statistics and the Wilcoxon test. The significance level was of p < 0.05. It was possible to analyze that the continuous and the intermittent jump test presented significant differences in MP (p < 0.05, FI (p < 0.01, and in the number of the vertical jump in 60 seconds (p < 0.01, and the height in 60 seconds exercise (p < 0.05. The MP found in IJ4x15sec was significantly higher than in the CJ60 sec in volleyball

  9. Development of a phase counter with real-time fringe jump corrector for heterodyne interferometer on LHD

    International Nuclear Information System (INIS)

    Ito, Y.; Tanaka, K.; Tokuzawa, T.; Akiyama, T.; Okajima, S.; Kawahata, K.

    2005-01-01

    Phase counters, which are used with heterodyne interferometers for plasma density measurements, frequently suffer from phase jumping and cause difficulties for data interpretation. An automatic fringe jump corrector (AFJC) circuit has been developed to compensate for fringe jumps. The AFJC can correct phase jumps automatically in real-time. The AFJC, which is integrated on one chip, is installed on the presently working phase counter circuit. As for the specification of this phase counter the intermediate beat signal is 1 MHz, the phase detection range is 31 fringes with phase resolution of 1/80 of a fringe and the response time of 10 μs. The circuit has been tested on the far infrared (FIR) laser interferometer on LHD. The AFJC works fine to correct fringe jumps, when fringe jumps occurred due to the strong density gradient produced by the hydrogen pellet injection

  10. Improved safety in ski jumping.

    Science.gov (United States)

    Wester, K

    1988-01-01

    Among approximately 2,600 licensed Norwegian ski jumpers, only three injuries that caused a permanent medical disability of at least 10% were incurred during the 5 year period from 1982 through 1986. When compared to the previous 5 year period (1977 to 1981), a dramatic improvement in safety is seen, as both number and severity of such injuries were markedly reduced. There are several probable reasons for this improved safety record: better preparation of the jumps, the return to using only one standard heel block, and the fact that coaches are being more responsible, especially with younger jumpers.

  11. Kinematics and Kinetics of Squats, Drop Jumps and Imitation Jumps of Ski Jumpers.

    Science.gov (United States)

    Pauli, Carole A; Keller, Melanie; Ammann, Fabian; Hübner, Klaus; Lindorfer, Julia; Taylor, William R; Lorenzetti, Silvio

    2016-03-01

    Squats, drop jumps, and imitation jumps are commonly used training exercises in ski jumping to enhance maximum force, explosive force, and sport-specific skills. The purpose of this study was to evaluate the kinetics and kinematics of training exercises in ski jumping and to find objective parameters in training exercises that most correlate with the competition performance of ski jumpers. To this end, barbell squats, drop jumps, and imitation jumps were measured in a laboratory environment for 10 elite ski jumpers. Force and motion data were captured, and the influence of maximum vertical force, force difference, vertical take-off velocity, knee moments, knee joint power, and a knee valgus/varus index was evaluated and correlated with their season jump performance. The results indicate that, especially for the imitation jumps, a good correlation exists between the vertical take-off velocity and the personal jump performance on the hill (R = 0.718). Importantly, however, the more the athletes tended toward a valgus knee alignment during the measured movements, the worse their performance (R = 0.729 imitation jumps; R = 0.685 squats). Although an evaluation of the athletes' lower limb alignment during competitive jumping on the hill is still required, these preliminary data suggest that performance training should additionally concentrate on improving knee alignment to increase ski jumping performance.

  12. Results of two years of water training on jump height in postmenopausal women with moderate hip risk fracture

    Directory of Open Access Journals (Sweden)

    María Carrasco Poyatos

    2010-01-01

    Full Text Available The aim of the present study was to investigate the effect of a water-based calisthenics and resistance program on jump height in postmenopausal women with moderate hip risk fracture. 39 women were divided into three groups: swimming group (GN; n = 17, calisthenics and resistance group (GIR; n = 14, and control group (GC; n = 8. Body composition test included body mass index (IMC and waist to hip ratio (ICC. Jump height was assessed by a countermovement jump (CMJ. GN showed a significant (p<0.05 decrease in ICC (5.81%. GIR showed a significant decrease in IMC (3.65% and a significant increase in CMJ (15.5%. Two years of water-based calisthenics and resistance training can offer significant benefits in jump height in postmenopausal women with moderate hip risk fracture. Both exercise programs can also improve body composition.

  13. Ocular complications of bungee jumping

    Directory of Open Access Journals (Sweden)

    Hassan HM

    2012-10-01

    Full Text Available H Mohammed J Hassan,1–3 Georgios Mariatos,1,2 Theocharis Papanikolaou,4 Akshatha Ranganath,1,2 Hala Hassan51Barnsley Hospital NHS Foundation Trust, Barnsley, UK; 2The Rotherham NHS Foundation Trust, Rotherham, UK; 3University of Sheffield, Sheffield, UK; 4North Middlesex University Hospital, London, UK; 5Corneal and External Disease Service, Moorefield's Eye Hospital NHS Foundation Trust, London, UKAim: In this paper, we will try to highlight the importance of various investigations and their crucial role in identifying whether the defect is structural or functional.Case history: A 24-year-old woman presented with ocular complications after bungee jumping. Subsequently, although all ophthalmic signs resolved, she complained of decreased vision in her left eye.Conclusion: Initial ophthalmic injury was detected by optical coherence tomography scan showing a neurosensory detachment of the fovea. This was not initially detected on slit-lamp examination or fluorescein angiography. On later examination, although the optical coherence tomography scan showed no structural damage, electrodiagnostic tests showed a functional defect at the fovea.Keywords: bungee jumping, optical coherence tomography, OCT, pattern electroretinogram, PERG, ocular complications

  14. Relationship between long jump and triple jump distances and the performance in running, jumping and strength tests

    Directory of Open Access Journals (Sweden)

    Felipe José Aidar

    2006-08-01

    Full Text Available The use of test batteries is the most common procedure to assess the specific preparation status of athletes. This procedure is also observed in the case of horizontal jumpers (long and triple jump. The aim of the present study was to investigate the associations between the performance in the long jump and in the triple jump and the performance in running, jumping and strength tests. Forty-five male physical education students performed competitions in long jump and triple jump after a month of technique learning. A week later, they were submitted to the following tests: 1 20 m maximum-speed running (20m; 2 standing long jump; 3 standing triple jump with alternate legs (TS; 4 maximum and mean isometric strength; 5 Squat Jump; 6 Counter Movement Jump; 7 Drop Jump. The 20m and the TS were the tests that showed a larger association with the competitive performance in the horizontal jumps and, altogether, they were able to explain about 50% of the variance of the results in the long jump and in the triple jump. We conclude that the 20m and the TS can be used to predict the performance of novices in the long jump and in the triple jump with an acceptable error (»6% e »4%, respectively. The results also suggest that running and horizontal jumping field tests are preferable than laboratory tests to assess the jumper’s fitness. ABSTRACT A aplicação de baterias de testes é o meio mais usual para avaliar o estado de forma de atletas de diversas especialidades. Assim sucede com os especialistas de saltos horizontais (salto em comprimento e triplo salto. O objectivo do presente estudo foi investigar a relação entre a prestação no Salto em Comprimento e no Triplo Salto e o desempenho em testes de corrida, impulsão e força isométrica. Quarenta e cinco estudantes de educação física do sexo masculino realizaram duas competições, uma de salto em comprimento e outra de triplo salto. Na semana seguinte foram submetidos aos seguintes testes: 1

  15. Jump frequency may contribute to risk of jumper's knee: a study of interindividual and sex differences in a total of 11,943 jumps video recorded during training and matches in young elite volleyball players.

    Science.gov (United States)

    Bahr, Martin A; Bahr, Roald

    2014-09-01

    Male sex, total training volume (number of hours per week) and match exposure (number of sets played per week) are risk factors for jumper's knee among young elite volleyball players. However, it is not known whether jump frequency differs among players on the same squad. To examine interindividual and sex differences in jump frequency during training and matches in young elite volleyball players. Observational study. Norwegian elite volleyball boarding school training programme. Student-athletes (26 boys and 18 girls, 16-18 years). Individual jump counts were recorded based on visual analysis of video recordings obtained from 1 week of volleyball training (9 training sessions for boys and 10 for girls, 14.1 h and 17.8 h of training, respectively) and 10 matches (5.9 h for boys (16 sets) and 7.7 h for girls (21 sets). A total of 11,943 jumps were recorded, 4138 during matches and 7805 during training. As training attendance and jump frequency varied substantially between players, the total exposure in training ranged from 50 to 666 jumps/week among boys and from 11 to 251 jumps/week among girls. On average, this corresponded to 35.7 jumps/h for boys and 13.7 jumps/h for girls (Student t test, p=0.002). Total jump exposure during matches ranged between 1 and 339 jumps among boys and between 0 and 379 jumps among girls, corresponding to an average jump frequency of 62.2 jumps/h for boys and 41.9 jumps/h for girls (Student t test, pvolleyball players. Total jump volume may represent a more important risk factor for jumper's knee than total training volume, warranting further research attention. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  16. Jump Detection in the Danish Stock Market

    DEFF Research Database (Denmark)

    Høg, Esben

    2002-01-01

    It is well known in financial economics that stock market return data are often modelled by a diffusion process with some regular drift function. Occasionally, however, sudden changes or jumps occur in the return data. Wavelet scaling methods are used to detect jumps and cusps in stock market...

  17. Separation and pattern formation in hydraulic jumps

    DEFF Research Database (Denmark)

    Bohr, Tomas; Ellegaard, C.; Hansen, A. Espe

    1998-01-01

    We present theory and experiments on the circular hydraulic jump in the stationary regime. The theory can handle the situation in which the fluid flows over an edge far away from the jump. In the experiments the external height is controlled, and a series of transitions in the flow structure appe...

  18. Biomechanical analysis of drop and countermovement jumps

    NARCIS (Netherlands)

    Bobbert, M. F.; Mackay, M.T.; Schinkelshoek, D.; Huijing, P. A.; van Ingen Schenau, G. J.

    For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle

  19. Usefulness of the jump-and-reach test in assessment of vertical jump performance.

    Science.gov (United States)

    Menzel, Hans-Joachim; Chagas, Mauro H; Szmuchrowski, Leszek A; Araujo, Silvia R; Campos, Carlos E; Giannetti, Marcus R

    2010-02-01

    The objective was to estimate the reliability and criterion-related validity of the Jump-and-Reach Test for the assessment of squat, countermovement, and drop jump performance of 32 male Brazilian professional volleyball players. Performance of squat, countermovement, and drop jumps with different dropping heights was assessed on the Jump-and-Reach Test and the measurement of flight time, then compared across different jump trials. The very high reliability coefficients of both assessment methods and the lower correlation coefficients between scores on the assessments indicate a very high consistency of each method but only moderate covariation, which means that they measure partly different items. As a consequence, the Jump-and-Reach Test has good ecological validity in situations when reaching height during the flight phase is critical for performance (e.g., basketball and volleyball) but only limited accuracy for the assessment of vertical impulse production with different jump techniques and conditions.

  20. A review on the basketball jump shot.

    Science.gov (United States)

    Okazaki, Victor H A; Rodacki, André L F; Satern, Miriam N

    2015-06-01

    The ability to shoot an effective jump shot in the sport of basketball is critical to a player's success. In an attempt to better understand the aspects related to expert performance, researchers have investigated successful free throws and jump shots of various basketball players and identified movement variables that contribute to their success. The purpose of this study was to complete a systematic review of the scientific literature on the basketball free throw and jump shot for the purpose of revealing the critical components of shooting that coaches, teachers, and players should focus on when teaching, learning, practising, and performing a jump shot. The results of this review are presented in three sections: (a) variables that affect ball trajectory, (b) phases of the jump shot, and (c) additional variables that influence shooting.

  1. Stochastic stability properties of jump linear systems

    Science.gov (United States)

    Feng, Xiangbo; Loparo, Kenneth A.; Ji, Yuandong; Chizeck, Howard J.

    1992-01-01

    Jump linear systems are defined as a family of linear systems with randomly jumping parameters (usually governed by a Markov jump process) and are used to model systems subject to failures or changes in structure. The authors study stochastic stability properties in jump linear systems and the relationship among various moment and sample path stability properties. It is shown that all second moment stability properties are equivalent and are sufficient for almost sure sample path stability, and a testable necessary and sufficient condition for second moment stability is derived. The Lyapunov exponent method for the study of almost sure sample stability is discussed, and a theorem which characterizes the Lyapunov exponents of jump linear systems is presented.

  2. Prediction of vertical jump height from anthropometric factors in male and female martial arts athletes.

    Science.gov (United States)

    Abidin, Nahdiya Zainal; Adam, Mohd Bakri

    2013-01-01

    Vertical jump is an index representing leg/kick power. The explosive movement of the kick is the key to scoring in martial arts competitions. It is important to determine factors that influence the vertical jump to help athletes improve their leg power. The objective of the present study is to identify anthropometric factors that influence vertical jump height for male and female martial arts athletes. Twenty-nine male and 25 female athletes participated in this study. Participants were Malaysian undergraduate students whose ages ranged from 18 to 24 years old. Their heights were measured using a stadiometer. The subjects were weighted using digital scale. Body mass index was calculated by kg/m(2). Waist-hip ratio was measured from the ratio of waist to hip circumferences. Body fat % was obtained from the sum of four skinfold thickness using Harpenden callipers. The highest vertical jump from a stationary standing position was recorded. The maximum grip was recorded using a dynamometer. For standing back strength, the maximum pull upwards using a handle bar was recorded. Multiple linear regression was used to obtain the relationship between vertical jump height and explanatory variables with gender effect. Body fat % has a significant negative relationship with vertical jump height (P martial arts athletes can be predicted by body fat %. The vertical jump for male is higher than for their female counterparts. Reducing body fat by proper dietary planning will help to improve leg power.

  3. EFFECTS OF PLYOMETRIC TRAINING ON THE DEVELOPMENT THE VERTICAL JUMP IN VOLLEYBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Soundara rajan R

    2010-08-01

    Full Text Available Abstract:The present study investigated the effect of plyometric training on development of the vertical jump of volleyball players. The study consisted of 30 male volleyball players from PSG College of Arts & Science, Coimbatore, their age ranged from 18 to 25 years. Participants articipants were randomly assigned Group I underwent plyometric training group and Group II control group. The plyometric training group carried out a set of plyometric exercises also designed by the researcher twice a week for six weeks. The control group was allowed to play their game, but they were not given any treatments. For the purpose of this research, two tests forthe evaluation of the volleyball vertical jump were validated: the block jump and spike jump. The data was analysed using Paired t-tests which were used to test the effect of treatment groups individually between pre and post –tests, of all the groups, on variables used in the present study. The analysis of covariance was used toanalsze the collected data. The result of the study reveals that there was significant difference in 0.05 levels.Based on the findings of the research and the discussion, one could conclude that the exercise model for the development of the vertical jump that had been used, as the fundamental factor of the experimental group, has contributed to the statistically significant difference in the increase of the vertical jump in comparison to thecontrol group, which had used technically tactical contents to develop the vertical jump.

  4. Variability of Jump Kinetics Related to Training Load in Elite Female Basketball

    Directory of Open Access Journals (Sweden)

    Jan Legg

    2017-11-01

    Full Text Available The purpose of this study was to quantify changes in jump performance and variability in elite female basketballers. Junior and senior female representative basketball players (n = 10 aged 18 ± 2 years participated in this study. Countermovement jump (CMJ data was collected with a Gymaware™ optical encoder at pre-, mid-, and post-season time points across 10 weeks. Jump performance was maintained across the course of the full season (from pre to post. Concentric peak velocity, jump height, and dip showed the most stability from pre- to post-season, with the %CV ranging from 5.6–8.9%. In the period of the highest training load (mid-season, the variability of within-subject performance was reduced by approximately 2–4% in all measures except for jump height. Altered jump mechanics through a small (0.26 effect size increase in dip were evident at mid-season, suggesting that CMJ analysis is useful for coaches to use as an in-season monitoring tool. The highest coefficient of variation (8–22%CV in inter-set scores in all measures except eccentric peak velocity also occurred mid-season. It appears that in-season load not only impairs jump performance, but also movement variability in basketball players.

  5. Kinematics and Kinetics of Squats, Drop Jumps and Imitation Jumps of Ski Jumpers

    Science.gov (United States)

    Pauli, Carole A.; Keller, Melanie; Ammann, Fabian; Hübner, Klaus; Lindorfer, Julia; Taylor, William R.

    2016-01-01

    Abstract Pauli, CA, Keller, M, Ammann, F, Hübner, K, Lindorfer, J, Taylor, WR, and Lorenzetti, S. Kinematics and kinetics of squats, drop jumps and imitation jumps of ski jumpers. J Strength Cond Res 30(3): 643–652, 2016—Squats, drop jumps, and imitation jumps are commonly used training exercises in ski jumping to enhance maximum force, explosive force, and sport-specific skills. The purpose of this study was to evaluate the kinetics and kinematics of training exercises in ski jumping and to find objective parameters in training exercises that most correlate with the competition performance of ski jumpers. To this end, barbell squats, drop jumps, and imitation jumps were measured in a laboratory environment for 10 elite ski jumpers. Force and motion data were captured, and the influence of maximum vertical force, force difference, vertical take-off velocity, knee moments, knee joint power, and a knee valgus/varus index was evaluated and correlated with their season jump performance. The results indicate that, especially for the imitation jumps, a good correlation exists between the vertical take-off velocity and the personal jump performance on the hill (R = 0.718). Importantly, however, the more the athletes tended toward a valgus knee alignment during the measured movements, the worse their performance (R = 0.729 imitation jumps; R = 0.685 squats). Although an evaluation of the athletes' lower limb alignment during competitive jumping on the hill is still required, these preliminary data suggest that performance training should additionally concentrate on improving knee alignment to increase ski jumping performance. PMID:26418370

  6. Predicting Vertical Jump Height from Bar Velocity

    Directory of Open Access Journals (Sweden)

    Amador García-Ramos, Igor Štirn, Paulino Padial, Javier Argüelles-Cienfuegos, Blanca De la Fuente, Vojko Strojnik, Belén Feriche

    2015-06-01

    Full Text Available The objective of the study was to assess the use of maximum (Vmax and final propulsive phase (FPV bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s-2. Vertical jump height was calculated from the take-off velocity (Vtake-off provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384 was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504 was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r2 = 0.307, while the differences between Vmax and Vtake-off were homogenously distributed (r2 = 0.071. These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine.

  7. Evaluation of an expanded microarray for detecting antibiotic resistance genes in a broad range of gram-negative bacterial pathogens.

    Science.gov (United States)

    Card, Roderick; Zhang, Jiancheng; Das, Priya; Cook, Charlotte; Woodford, Neil; Anjum, Muna F

    2013-01-01

    A microarray capable of detecting genes for resistance to 75 clinically relevant antibiotics encompassing 19 different antimicrobial classes was tested on 132 Gram-negative bacteria. Microarray-positive results correlated >91% with antimicrobial resistance phenotypes, assessed using British Society for Antimicrobial Chemotherapy clinical breakpoints; the overall test specificity was >83%. Microarray-positive results without a corresponding resistance phenotype matched 94% with PCR results, indicating accurate detection of genes present in the respective bacteria by microarray when expression was low or absent and, hence, undetectable by susceptibility testing. The low sensitivity and negative predictive values of the microarray results for identifying resistance to some antimicrobial resistance classes are likely due to the limited number of resistance genes present on the current microarray for those antimicrobial agents or to mutation-based resistance mechanisms. With regular updates, this microarray can be used for clinical diagnostics to help accurate therapeutic options to be taken following infection with multiple-antibiotic-resistant Gram-negative bacteria and prevent treatment failure.

  8. Realized Jump Risk and Equity Return in China

    Directory of Open Access Journals (Sweden)

    Guojin Chen

    2014-01-01

    Full Text Available We utilize the realized jump components to explore a new jump (including nonsystematic jump and systematic jump risk factor model. After estimating daily realized jumps from high-frequency transaction data of the Chinese A-share stocks, we calculate monthly jump size, monthly jump standard deviation, and monthly jump arrival rate and then use those monthly jump factors to explain the return of the following month. Our empirical results show that the jump tail risk can explain the equity return. For the large capital-size stocks, large cap stock portfolios, and index, one-month lagged jump risk factor significantly explains the asset return variation. Our results remain the same even when we add the size and value factors in the robustness tests.

  9. The effect of assisted jumping on vertical jump height in high-performance volleyball players.

    Science.gov (United States)

    Sheppard, Jeremy M; Dingley, Andrew A; Janssen, Ina; Spratford, Wayne; Chapman, Dale W; Newton, Robert U

    2011-01-01

    Assisted jumping may be useful in training higher concentric movement speed in jumping, thereby potentially increasing the jumping abilities of athletes. The purpose of this study was to evaluate the effects of assisted jump training on counter-movement vertical jump (CMVJ) and spike jump (SPJ) ability in a group of elite male volleyball players. Seven junior national team volleyball players (18.0±1.0 yrs, 200.4±6.7 cm, and 84.0±7.2 kg) participated in this within-subjects cross-over counter-balanced training study. Assisted training involved 3 sessions per week of CMVJ training with 10 kg of assistance, applied through use of a bungee system, whilst normal jump training involved equated volume of unassisted counter-movement vertical jumps. Training periods were 5 weeks duration, with a 3-week wash-out separating them. Prior to and at the conclusion of each training period jump testing for CMVJ and SPJ height was conducted. Assisted jump training resulted in gains of 2.7±0.7 cm (pSports Medicine Australia. All rights reserved.

  10. Breast Support Garments are Ineffective at Reducing Breast Motion During an Aqua Aerobics Jumping Exercise

    Directory of Open Access Journals (Sweden)

    Mills Chris

    2015-06-01

    Full Text Available The buoyant forces of water during aquatic exercise may provide a form of ‘natural’ breast support and help to minimise breast motion and alleviate exercise induced breast pain. Six larger-breasted females performed standing vertical land and water-based jumps, whilst wearing three breast support conditions. Underwater video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated as well as exercised induced breast pain scores. Key results showed that the swimsuit and sports bra were able to significantly reduce the superioinferior breast range of motion by 0.04 and 0.05 m, respectively, and peak velocity by 0.23 and 0.33 m/s, respectively, during land-based jumping when compared to the bare-breasted condition, but were ineffective at reducing breast kinematics during water-based jumping. Furthermore, the magnitude of the swimsuit superioinferior breast range of motion during water-based jumping was significantly greater than land-based jumping (0.13 m and 0.06 m, yet there were no significant differences in exercise induced breast pain, thus contradicting previously published relationships between these parameters on land. Furthermore, the addition of an external breast support garment was able to reduce breast kinematics on land but not in water, suggesting the swimsuit and sports bras were ineffective and improvements in swimwear breast support garments may help to reduce excessive breast motion during aqua aerobic jumping exercises.

  11. Breast Support Garments are Ineffective at Reducing Breast Motion During an Aqua Aerobics Jumping Exercise.

    Science.gov (United States)

    Mills, Chris; Ayres, Bessie; Scurr, Joanna

    2015-06-27

    The buoyant forces of water during aquatic exercise may provide a form of 'natural' breast support and help to minimise breast motion and alleviate exercise induced breast pain. Six larger-breasted females performed standing vertical land and water-based jumps, whilst wearing three breast support conditions. Underwater video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated as well as exercised induced breast pain scores. Key results showed that the swimsuit and sports bra were able to significantly reduce the superioinferior breast range of motion by 0.04 and 0.05 m, respectively, and peak velocity by 0.23 and 0.33 m/s, respectively, during land-based jumping when compared to the bare-breasted condition, but were ineffective at reducing breast kinematics during water-based jumping. Furthermore, the magnitude of the swimsuit superioinferior breast range of motion during water-based jumping was significantly greater than land-based jumping (0.13 m and 0.06 m), yet there were no significant differences in exercise induced breast pain, thus contradicting previously published relationships between these parameters on land. Furthermore, the addition of an external breast support garment was able to reduce breast kinematics on land but not in water, suggesting the swimsuit and sports bras were ineffective and improvements in swimwear breast support garments may help to reduce excessive breast motion during aqua aerobic jumping exercises.

  12. Construction of an extended range whole-cell tetracycline biosensor by use of the tet(M) resistance gene

    DEFF Research Database (Denmark)

    Bahl, Martin Iain; Hansen, Lars Hestbjerg; Sørensen, Søren Johannes

    2005-01-01

    An extended range whole-cell tetracycline biosensor strain was constructed by insertion of the tet(M) gene, encoding tetracycline resistance by ribosomal protection, into plasmid pTGFP2, which contains a transcriptional fusion between a tetracycline regulated promoter and the green fluorescent...... to drug concentrations ranging from below 5 ng ml-1 to 16 µg ml-1, which represents a significant improvement of the original version....

  13. The Effects of Aquatic Plyometric Training on Repeated Jumps, Drop Jumps and Muscle Damage.

    Science.gov (United States)

    Jurado-Lavanant, A; Alvero-Cruz, J R; Pareja-Blanco, F; Melero-Romero, C; Rodríguez-Rosell, D; Fernandez-Garcia, J C

    2015-09-22

    The purpose of this study was to compare the effects of land- vs. aquatic based plyometric training programs on the drop jump, repeated jump performance and muscle damage. Sixty-five male students were randomly assigned to one of 3 groups: aquatic plyometric training group (APT), plyometric training group (PT) and control group (CG). Both experimental groups trained twice a week for 10 weeks performing the same number of sets and total jumps. The following variables were measured prior to, halfway through and after the training programs: creatine kinase (CK) concentration, maximal height during a drop jump from the height of 30 (DJ30) and 50 cm (DJ50), and mean height during a repeated vertical jump test (RJ). The training program resulted in a significant increase (Pplyometric training, PT produced greater gains on reactive jumps performance than APT. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Empirical ranking of a wide range of WC-Co grades in terms of their abrasion resistance measured by the ASTM standard B 611-85 test

    CSIR Research Space (South Africa)

    O'Quigley, DGF

    1997-01-01

    Full Text Available This paper reports the results of a comprehensive investigation into the abrasion resistance of WC-Co alloys, as measured by the ASTM Standard B 611-85 test. The alloys ranged from 3 to 50 wt% and from 0.6 to 5 mu-m average grain size. Careful...

  15. Phenotypic and Genotypic Antimicrobial Resistance Profiles of Campylobacter jejuni Isolated from Cattle, Sheep, and Free-Range Poultry Faeces

    Directory of Open Access Journals (Sweden)

    Beatriz Oporto

    2009-01-01

    Full Text Available Minimum inhibitory concentrations (MIC of 13 antimicrobial agents were determined by broth microdilution for 72 Campylobacter jejuni strains from livestock. Twenty-three (31.9% isolates were fully susceptible; all isolates were susceptible to erythromycin, chloramphenicol, streptomycin, gentamicin, sulfamethoxazole, and meropenem, and all but one to kanamycin. Resistance to quinolones was highest (52.8%, reaching similar values among poultry, dairy cattle, and sheep, but lower in beef cattle. Resistance to tetracyclines (48.6% was mainly associated to dairy cattle and β-lactams (26.4% to poultry. Multidrug resistance was mainly detected in dairy cattle (28.6% and poultry (21.0%, whereas beef cattle had the highest percentage of fully susceptible isolates. Two real-time PCR assays to detect point mutations associated to quinolone (C257T in the gyrA gene and macrolide (A2075G in the 23S rRNA genes resistance were developed and validated on these strains. The analysis of a further set of 88 isolates by real-time PCR confirmed the absence of macrolide resistance and demonstrated the reproducibility and processability of the assay.

  16. Effects of 18-week in-season heavy-resistance and power training on throwing velocity, strength, jumping, and maximal sprint swim performance of elite male water polo players.

    Science.gov (United States)

    Ramos Veliz, Rafael; Requena, Bernardo; Suarez-Arrones, Luis; Newton, Robert U; Sáez de Villarreal, Eduardo

    2014-04-01

    We examined the effects of 18 weeks of strength and high-intensity training on key sport performance measures of elite male water polo (WP) players. Twenty-seven players were randomly assigned to 2 groups, control (in-water training only) and strength group, (strength training sessions [twice per week] + in-water training). In-water training was conducted 5 d·wk. Twenty-meter maximal sprint swim, maximal dynamic strength 1-repetition maximum (1RM) for upper bench press (BP) and lower full squat (FS) body, countermovement jump (CMJ), and throwing velocity were measured before and after the training. The training program included upper and lower body strength and high-intensity exercises (BP, FS, military press, pull-ups, CMJ loaded, and abs). Baseline-training results showed no significant differences between the groups in any of the variables tested. No improvement was found in the control group; however, meaningful improvement was found in all variables in the experimental group: CMJ (2.38 cm, 6.9%, effect size [ES] = 0.48), BP (9.06 kg, 10.53%, ES = 0.66), FS (11.06 kg, 14.21%, ES = 0.67), throwing velocity (1.76 km·h(-1), 2.76%, ES = 0.25), and 20-m maximal sprint swim (-0.26 seconds, 2.25%, ES = 0.29). Specific strength and high-intensity training in male WP players for 18 weeks produced a positive effect on performance qualities highly specific to WP. Therefore, we propose modifications to the current training methodology for WP players to include strength and high-intensity training for athlete preparation in this sport.

  17. Volatility jumps and their economic determinants

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    that there is a positive probability of jumps in volatility. A common factor in the volatility jumps is shown to be related to a set of financial covariates (such as variance risk premium, S&P500 volume, credit-default swap, and federal fund rates). The credit-default swap on US banks and variance risk premium have...... predictive power on expected jump moves, thus confirming the common interpretation that sudden and large increases in equity volatility can be anticipated by credit deterioration of the US bank sector as well as changes in the market expectations of future risks. Finally, the model is extended to incorporate...... the credit-default swap and the variance risk premium in the dynamics of the jump size and intensity....

  18. Jump spillover between oil prices and exchange rates

    Science.gov (United States)

    Li, Xiao-Ping; Zhou, Chun-Yang; Wu, Chong-Feng

    2017-11-01

    In this paper, we investigate the jump spillover effects between oil prices and exchange rates. To identify the latent historical jumps for exchange rates and oil prices, we use a Bayesian MCMC approach to estimate the stochastic volatility model with correlated jumps in both returns and volatilities for each. We examine the simultaneous jump intensities and the conditional jump spillover probabilities between oil prices and exchange rates, finding strong evidence of jump spillover effects. Further analysis shows that the jump spillovers are mainly due to exogenous events such as financial crises and geopolitical events. Thus, the findings have important implications for financial risk management.

  19. Jump Horse Safety: Reconciling Public Debate and Australian Thoroughbred Jump Racing Data, 2012–2014

    Directory of Open Access Journals (Sweden)

    Karen Ruse

    2015-10-01

    Full Text Available Thoroughbred jump racing sits in the spotlight of contemporary welfare and ethical debates about horse racing. In Australia, jump racing comprises hurdle and steeplechase races and has ceased in all but two states, Victoria and South Australia. This paper documents the size, geography, composition, and dynamics of Australian jump racing for the 2012, 2013, and 2014 seasons with a focus on debate about risks to horses. We found that the majority of Australian jump racing is regional, based in Victoria, and involves a small group of experienced trainers and jockeys. Australian jump horses are on average 6.4 years of age. The jump career of the majority of horses involves participating in three or less hurdle races and over one season. Almost one quarter of Australian jump horses race only once. There were ten horse fatalities in races over the study period, with an overall fatality rate of 5.1 fatalities per 1000 horses starting in a jump race (0.51%. There was significant disparity between the fatality rate for hurdles, 0.75 fatalities per 1000 starts (0.075% and steeplechases, 14 fatalities per 1000 starts (1.4%. Safety initiatives introduced by regulators in 2010 appear to have significantly decreased risks to horses in hurdles but have had little or no effect in steeplechases. Our discussion considers these Animals 2015, 5 1073 data in light of public controversy, political debate, and industry regulation related to jump horse safety.

  20. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2010-01-01

    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  1. A jumping shape memory alloy under heat.

    Science.gov (United States)

    Yang, Shuiyuan; Omori, Toshihiro; Wang, Cuiping; Liu, Yong; Nagasako, Makoto; Ruan, Jingjing; Kainuma, Ryosuke; Ishida, Kiyohito; Liu, Xingjun

    2016-02-16

    Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L2(1) parent before deformation, the 2H martensite stress-induced from L2(1) parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.

  2. Might as well jump: sound affects muscle activation in skateboarding.

    Directory of Open Access Journals (Sweden)

    Paola Cesari

    Full Text Available The aim of the study is to reveal the role of sound in action anticipation and performance, and to test whether the level of precision in action planning and execution is related to the level of sensorimotor skills and experience that listeners possess about a specific action. Individuals ranging from 18 to 75 years of age--some of them without any skills in skateboarding and others experts in this sport--were compared in their ability to anticipate and simulate a skateboarding jump by listening to the sound it produces. Only skaters were able to modulate the forces underfoot and to apply muscle synergies that closely resembled the ones that a skater would use if actually jumping on a skateboard. More importantly we showed that only skaters were able to plan the action by activating anticipatory postural adjustments about 200 ms after the jump event. We conclude that expert patterns are guided by auditory events that trigger proper anticipations of the corresponding patterns of movements.

  3. Landscape resistance and habitat combine to provide an optimal model of genetic structure and connectivity at the range margin of a small mammal.

    Science.gov (United States)

    Marrotte, R R; Gonzalez, A; Millien, V

    2014-08-01

    We evaluated the effect of habitat and landscape characteristics on the population genetic structure of the white-footed mouse. We develop a new approach that uses numerical optimization to define a model that combines site differences and landscape resistance to explain the genetic differentiation between mouse populations inhabiting forest patches in southern Québec. We used ecological distance computed from resistance surfaces with Circuitscape to infer the effect of the landscape matrix on gene flow. We calculated site differences using a site index of habitat characteristics. A model that combined site differences and resistance distances explained a high proportion of the variance in genetic differentiation and outperformed models that used geographical distance alone. Urban and agriculture-related land uses were, respectively, the most and the least resistant landscape features influencing gene flow. Our method detected the effect of rivers and highways as highly resistant linear barriers. The density of grass and shrubs on the ground best explained the variation in the site index of habitat characteristics. Our model indicates that movement of white-footed mouse in this region is constrained along routes of low resistance. Our approach can generate models that may improve predictions of future northward range expansion of this small mammal. © 2014 John Wiley & Sons Ltd.

  4. Jumping From a Chair is a More Sensitive Measure of Power Performance In Older Adults Than Chair Rising.

    Science.gov (United States)

    Zemková, Erika; Jeleň, Michal; Schickhofer, Peter; Hamar, Dušan

    2016-01-01

    Background/Study Context: The study estimates the reliability of peak velocity and peak power during chair rising and chair jumping tests and their ability to discriminate between different age and physical activity level groups. Physically active and sedentary individuals (N = 262) of different ages (young: 22.9 ± 2.0 years, range: 21-25 years; older: 63.1 ± 1.8 years, range: 61-65 years) performed, in random order, chair rising and chair jumping tests on a force plate. Randomly selected young subjects performed both tests repeatedly on two different occasions separated by 1 week. From the sitting position with the arms crossed on the chest, they either stand up completely (chair rising test), or jump as high as possible (chair jumping test). The test-retest reliability of peak power and peak velocity during chair rising as well as chair jumping was excellent, with high intraclass correlation coefficients (ICCs; .90-.98) and low standard error of measurement (SEM; 7.0-9.1%). Post hoc analysis revealed significant differences in peak power and peak velocity between the sedentary and physically active young and older subjects. However, greater coefficients of variation for both parameters were found for chair jumping than chair rising (21.1-40.2% vs. 11.0-15.2%). Additionaly, there were moderate correlations of peak power and peak velocity between chair rising and chair jumping (r = .42-.49). There were greater within- and between-group differences in peak force and peak power and a steeper increase in their values during the initial phase of chair jumping than chair rising. Both chair rising and chair jumping tests provide reliable data and are valid indicators of lower body power in young and older adults. However, jumping from a chair is a more sensitive measure of strength and power performance than chair rising.

  5. Interaction of the human body and surfaces of different stiffness during drop jumps.

    Science.gov (United States)

    Arampatzis, Adamantios; Stafilidis, Savvas; Morey-Klapsing, Gaspar; Brüggemann, Gert-peter

    2004-03-01

    The purpose of this study was to examine two hypotheses: (a) the stiffness of the surface influences the leg stiffness of the subjects during drop jumps, and (b) drop jumping performance (jumping height and energy rates of the subject's center of mass during the contact phase) increases when decreasing surface stiffness due to a greater energy storage capacity of the surface for a given acting force. Ten female subjects performed a series of drop jumps from 40-cm height onto two sprung surfaces with different stiffness. Those trials of each subject displaying the maximal mechanical power during the upward phase were analyzed. The ground reaction forces were measured using a force plate. Sagittal kinematics of the subject's body positions and the deformation of the surface were recorded using two high-speed video cameras. On the soft surface, the jumping height and the energy rates of the subjects during the contact phase were greater than on the hard one. The energy delivered by the subjects during the upward phase, the leg and joint stiffness, as well as the range of motion of the subjects remained unchanged for both surfaces. The absolute energy loss is lower for the hard surface, but the jumping performance is greater for the soft one. The reason is a higher ratio of positive to negative mechanical work done by the subjects during the contact phase. The adjustment of the subjects to different surfaces is not only dependent on the stiffness of the surface but also on the intensity of the movement.

  6. Validity and reliability of the Myotest accelerometric system for the assessment of vertical jump height.

    Science.gov (United States)

    Casartelli, Nicola; Müller, Roland; Maffiuletti, Nicola A

    2010-11-01

    The aim of the present study was to verify the validity and reliability of the Myotest accelerometric system (Myotest SA, Sion, Switzerland) for the assessment of vertical jump height. Forty-four male basketball players (age range: 9-25 years) performed series of squat, countermovement and repeated jumps during 2 identical test sessions separated by 2-15 days. Flight height was simultaneously quantified with the Myotest system and validated photoelectric cells (Optojump). Two calculation methods were used to estimate the jump height from Myotest recordings: flight time (Myotest-T) and vertical takeoff velocity (Myotest-V). Concurrent validity was investigated comparing Myotest-T and Myotest-V to the criterion method (Optojump), and test-retest reliability was also examined. As regards validity, Myotest-T overestimated jumping height compared to Optojump (p 0.98), that is, excellent validity. Myotest-V overestimated jumping height compared to Optojump (p 12 cm), high limits of agreement ratios (>36%), and low ICCs (9 cm). In conclusion, Myotest-T is a valid and reliable method for the assessment of vertical jump height, and its use is legitimate for field-based evaluations, whereas Myotest-V is neither valid nor reliable.

  7. Jump Horse Safety: Reconciling Public Debate and Australian Thoroughbred Jump Racing Data, 2012–2014

    Science.gov (United States)

    Ruse, Karen; Davison, Aidan; Bridle, Kerry

    2015-01-01

    Simple Summary This paper documents the dynamics of Australian thoroughbred jump racing in the 2012, 2013, and 2014 seasons with the aim of informing debate about risks to horses and the future of this activity. We conclude that the safety of Australian jump racing has improved in recent years but that steeplechases are considerably riskier for horses than hurdle races. Abstract Thoroughbred jump racing sits in the spotlight of contemporary welfare and ethical debates about horse racing. In Australia, jump racing comprises hurdle and steeplechase races and has ceased in all but two states, Victoria and South Australia. This paper documents the size, geography, composition, and dynamics of Australian jump racing for the 2012, 2013, and 2014 seasons with a focus on debate about risks to horses. We found that the majority of Australian jump racing is regional, based in Victoria, and involves a small group of experienced trainers and jockeys. Australian jump horses are on average 6.4 years of age. The jump career of the majority of horses involves participating in three or less hurdle races and over one season. Almost one quarter of Australian jump horses race only once. There were ten horse fatalities in races over the study period, with an overall fatality rate of 5.1 fatalities per 1000 horses starting in a jump race (0.51%). There was significant disparity between the fatality rate for hurdles, 0.75 fatalities per 1000 starts (0.075%) and steeplechases, 14 fatalities per 1000 starts (1.4%). Safety initiatives introduced by regulators in 2010 appear to have significantly decreased risks to horses in hurdles but have had little or no effect in steeplechases. Our discussion considers these data in light of public controversy, political debate, and industry regulation related to jump horse safety. PMID:26506396

  8. Energy expended during horizontal jumping: investigating the effects of surface compliance

    Directory of Open Access Journals (Sweden)

    Samuel R. L. Coward

    2014-08-01

    Full Text Available We present the first data on the metabolic costs of horizontal jumping in humans, using this tractable model to explore variations in energy expenditure with substrate properties, and consider these findings in light of kinematic data. Twenty-four participants jumped consistently at the rate of 1 jump per 5 s between opposing springboards separated by either a short (1.2 m or long (1.8 m gap. Springboards were either ‘firm’ or ‘compliant’. Respiratory gas exchange was measured using a back-mounted portable respiratory gas analyser to represent rate of energy expenditure, which was converted to energy expenditure per metre jumped. Video data were recorded to interpret kinematic information. Horizontal jumping was found to be between around 10 and 20 times the energy cost of cursorial locomotion per unit distance moved. There is considerable evidence from the data that jumping 1.8 m from a compliant springboard (134.9 mL O2 m−1 is less costly energetically than jumping that distance from a firm springboard (141.6 mL O2 m−1, albeit the effect size is quite small within the range of compliances tested in this study. However, there was no evidence of an effect of springboard type for jumps of 1.2 m. The kinematic analyses indicate possible explanations for these findings. Firstly, the calf muscle is likely used more, and the thigh muscles less, to take-off from a firm springboard during 1.8 m jumps, which may result in the power required to take-off being produced less efficiently. Secondly, the angle of take-off from the compliant surface during 1.8 m jumps is closer to the optimal for energetic efficiency (45°, possible due to the impulse provided by the surface as it returns stored energy during the final stages of the take-off. The theoretical effect on energy costs due to a different take-off angle for jumps of only 1.2 m is close to negligible.

  9. The Effects of Eccentric Contraction Duration on Muscle Strength, Power Production, Vertical Jump, and Soreness.

    Science.gov (United States)

    Mike, Jonathan N; Cole, Nathan; Herrera, Chris; VanDusseldorp, Trisha; Kravitz, Len; Kerksick, Chad M

    2017-03-01

    Mike, JN, Cole, N, Herrera, C, VanDusseldorp, T, Kravitz, L, and Kerksick, CM. The effects of eccentric contraction duration on muscle strength, power production, vertical jump, and soreness. J Strength Cond Res 31(3): 773-786, 2017-Previous research has investigated the effects of either eccentric-only training or comparing eccentric and concentric exercise on changes related to strength and power expression, but no research to date has investigated the impact of altering the duration of either the concentric or the eccentric component on these parameters. Therefore, the purpose of this study was to assess the duration of eccentric (i.e., 2-second, 4-second vs. 6-second) muscle contractions and their effect on muscle strength, power production, vertical jump, and soreness using a plate-loaded barbell Smith squat exercise. Thirty college-aged men (23 ± 3.5 years, 178 ± 6.8 cm, 82 ± 12 kg, and 11.6 ± 5.1% fat) with 3.0 ± 1.0 years of resistance training experience and training frequency of 4.3 ± 0.9 days per week were randomized and assigned to 1 of 3 eccentric training groups that incorporated different patterns of contraction. For every repetition, all 3 groups used 2-second concentric contractions and paused for 1 second between the concentric and eccentric phases. The control group (2S) used 2-second eccentric contractions, whereas the 4S group performed 4-second eccentric contractions and the 6S group performed 6-second eccentric contractions. All repetitions were completed using the barbell Smith squat exercise. All participants completed a 4-week training protocol that required them to complete 2 workouts per week using their prescribed contraction routine for 4 sets of 6 repetitions at an intensity of 80-85% one repetition maximum (1RM). For all performance data, significant group × time (G × T) interaction effects were found for average power production across all 3 sets of a squat jump protocol (p = 0.04) while vertical jump did not reach

  10. The role of human ankle plantar flexor muscle-tendon interaction and architecture in maximal vertical jumping examined in vivo.

    Science.gov (United States)

    Farris, Dominic James; Lichtwark, Glen A; Brown, Nicholas A T; Cresswell, Andrew G

    2016-02-01

    Humans utilise elastic tendons of lower limb muscles to store and return energy during walking, running and jumping. Anuran and insect species use skeletal structures and/or dynamics in conjunction with similarly compliant structures to amplify muscle power output during jumping. We sought to examine whether human jumpers use similar mechanisms to aid elastic energy usage in the plantar flexor muscles during maximal vertical jumping. Ten male athletes performed maximal vertical squat jumps. Three-dimensional motion capture and a musculoskeletal model were used to determine lower limb kinematics that were combined with ground reaction force data in an inverse dynamics analysis. B-mode ultrasound imaging of the lateral gastrocnemius (GAS) and soleus (SOL) muscles was used to measure muscle fascicle lengths and pennation angles during jumping. Our results highlighted that both GAS and SOL utilised stretch and recoil of their series elastic elements (SEEs) in a catapult-like fashion, which likely serves to maximise ankle joint power. The resistance of supporting of body weight allowed initial stretch of both GAS and SOL SEEs. A proximal-to-distal sequence of joint moments and decreasing effective mechanical advantage early in the extension phase of the jumping movement were observed. This facilitated a further stretch of the SEE of the biarticular GAS and delayed recoil of the SOL SEE. However, effective mechanical advantage did not increase late in the jump to aid recoil of elastic tissues. © 2016. Published by The Company of Biologists Ltd.

  11. Differences In Male Collegiate And Recreationally Trained Soccer Players On Balance, Agility, And Vertical Jump Performance

    Directory of Open Access Journals (Sweden)

    Nicole M. Sauls

    2017-10-01

    Full Text Available Objective: The purpose of this investigation was to determine the differences in collegiate and recreationally trained soccer players in sprint, vertical jump, and balance performance. Methods: Twenty-one soccer players, twelve Division II collegiate and nine recreationally trained volunteered to participate. Session one acted as a familiarization day, where the participants were familiarized with testing day protocols. During testing day, participants performed a dynamic warm-up, followed by balance measurements, three countermovement vertical jumps, and pro-agility shuttle test. Results: There were no significant (p>0.05 differences between groups in the all balance variables. Collegiate soccer players had a significantly (p0.05 differences in groups in all other variables. Conclusion: These results indicate that collegiate, Division II, soccer players had greater vertical jumping and sprinting velocities when compared to recreationally trained soccer players. These results may have been impacted by the lack of resistance training background in either of the two groups. With the addition of more time on a collegiate resistance training program, it is very likely the Division II athletes will see a significant increase in all balance, sprint, and vertical jump performance measures compared to recreationally trained players who receive little to no specialized resistance training.

  12. Achyrofuran is an antibacterial agent capable of killing methicillin-resistant vancomycin-intermediate Staphylococcus aureus in the nanomolar range.

    Science.gov (United States)

    Casero, Carina; Estévez-Braun, Ana; Ravelo, Angel G; Demo, Mirta; Méndez-Álvarez, Sebastián; Machín, Félix

    2013-01-15

    Currently, there is a pressing need for novel antibacterial agents against drug-resistant bacteria, especially those which have been common in our communities and hospitals, such as methicillin-resistant Staphylococcus aureus (MRSA). The South American plant Achyrocline satureioides ("Marcela") has been widely used in traditional medicine for a number of diseases, including infections. Several crude extracts from this plant have shown good antimicrobial activities in vitro. In the search for the active principle(s) that confers these antimicrobial activities, we have processed the dichloromethane extract from the aerial parts of the plant. One of the isolated compounds showed extraordinary antibacterial activities against a set of clinically relevant Gram-positive strains that widely differ in their antibiogram profiles. This compound was identified as achyrofuran on the basis of its spectroscopic and physical data. We determined the MIC to be around 0.1 μM (0.07 μg/ml) for the reference methicillin-resistant and vancomycin-intermediate S. aureus strain NRS402. Moreover, nanomolar concentrations of achyrofuran killed 10(6) bacteria within 12 h. Based on the presence of the 2,2'-biphenol core, we further studied whether achyrofuran killed bacteria through a mechanism of action similar to that reported for the naturally occurring antibiotic MC21-A. Indeed, we found that achyrofuran was not bacteriolytic by itself although it greatly compromised membrane impermeability as determined by increased SYTOX Green uptake. Copyright © 2012 Elsevier GmbH. All rights reserved.

  13. Experimental study of the hydraulic jump in a hydraulic jump in a ...

    African Journals Online (AJOL)

    The hydraulic jump in a sloped rectangular channel is theoretically and experimentally examined. The study aims to determine the effect of the channel's slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope.

  14. Increase in Jumping Height Associated with Maximal Effort Vertical Depth Jumps.

    Science.gov (United States)

    Bedi, John F.; And Others

    1987-01-01

    In order to assess if there existed a statistically significant increase in jumping performance when dropping from different heights, 32 males, aged 19 to 26, performed a series of maximal effort vertical jumps after dropping from eight heights onto a force plate. Results are analyzed. (Author/MT)

  15. Characterisation of β-lactam resistance mediated by blaZ in staphylococci recovered from captive and free-ranging wallabies.

    Science.gov (United States)

    Chen, Michelle M S; Boardman, Wayne S J; Smith, Ian; Goodman, Amanda E; Brown, Melissa H

    2015-09-01

    Staphylococci are commensal organisms of animals, but some species are opportunistic pathogens that are resistant to almost all antimicrobial agents in clinical use. Bacterial resistance to β-lactam antimicrobial agents is widespread and has been investigated in species isolated from humans in addition to food production and companion animals. However, minimal progress has been made towards identifying reservoirs of β-lactam-resistant staphylococci in wildlife. This study was aimed at investigating and characterising β-lactamase resistance from staphylococci of wallaby origin. Staphylococci from free-ranging and captive wallabies were assessed for their phenotypic susceptibility to β-lactam antimicrobial agents prior to sequence analysis of their blaZ and blaR1 genes. Deduced amino acid sequences were classified according to the Ambler molecular characterisation method, assigned a protein signature type and compared with sequences generated from previous studies involving isolates from humans, cattle and companion animals. All BlaZ sequences identified in this study were assignable to a pre-existing β-lactamase class and protein signature type, including the more recently discovered protein signature type 12. Three major phylogenetic groups were resolved upon phylogenetic analysis against published BlaZ sequences. This study has found antibiotic-resistant staphylococci both in free-ranging and captive wallaby populations and these bacteria harbour blaZ variants that are different to those recovered from humans, cattle and companion animals. Further studies of staphylococci from non-traditional sources are required in order to enhance our knowledge of the epidemiology of antibiotic resistance genes. Copyright © 2015 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  16. Antibiotic resistance, phylogenetic grouping and virulence potential of Escherichia coli isolated from the faeces of intensively farmed and free range poultry.

    Science.gov (United States)

    Obeng, Akua Serwaah; Rickard, Heather; Ndi, Olasumbo; Sexton, Margaret; Barton, Mary

    2012-01-27

    Antibiotic use in poultry production is a risk factor for promoting the emergence of resistant Escherichia coli. To ascertain differences in different classes of chickens, the resistance profile, some virulence genes and phylogenetic grouping on 251 E. coli isolates from intensive meat (free range and indoor commercial) and free range egg layer chickens collected between December 2008 and June 2009 in South Australia were performed. Among the 251 strains, 102 (40.6%) and 67 (26.7%) were found to be resistant to tetracycline and ampicillin respectively. Resistance was also observed to trimethoprim-sulfamethoxazole (12.4%), streptomycin (10.8%), spectinomycin (9.6%), neomycin (6.0%) and florfenicol (2.0%) but no resistance was found to ceftiofur, ciprofloxacin or gentamicin. Amplification of DNA of the isolates by polymerase chain reaction revealed the presence of genes that code for resistant determinants: tetracycline (tet(A), tet(B) and tet(C)), ampicillin (bla(TEM) and bla(SHV)), trimethoprim (dhfrV and dhfrXIII), sulphonamide (sulI and sulII), neomycin (aph(3)-Ia(aphA1)), and spectinomycin-streptinomycin (aadA2). In addition, 32.3-39.4% of the isolates were found to belong to commensal groups (A and B1) and 11.2-17.1% belonged to the virulent groups (B2 and D). Among the 251 E. coli isolates, 25 (10.0%) carried two or more virulence genes typical of Extraintestinal pathogenic E. coli (ExPEC). Furthermore, 17 of the isolates with multi-resistance were identified to be groups B2 and D. Although no significant difference was observed between isolates from free range and indoor commercial meat chickens (P>0.05), significant differences was observed between the different classes of meat chickens (free range and indoor commercial) and egg layers (P<0.05). While this study assessed the presence of a limited number of virulence genes, our study re emphasises the zoonotic potential of poultry E. coli isolates. Copyright © 2011. Published by Elsevier B.V.

  17. Determinants of the abilities to jump higher and shorten the contact time in a running 1-legged vertical jump in basketball.

    Science.gov (United States)

    Miura, Ken; Yamamoto, Masayoshi; Tamaki, Hiroyuki; Zushi, Koji

    2010-01-01

    This study was conducted to obtain useful information for developing training techniques for the running 1-legged vertical jump in basketball (lay-up shot jump). The ability to perform the lay-up shot jump and various basic jumps was measured by testing 19 male basketball players. The basic jumps consisted of the 1-legged repeated rebound jump, the 2-legged repeated rebound jump, and the countermovement jump. Jumping height, contact time, and jumping index (jumping height/contact time) were measured and calculated using a contact mat/computer system that recorded the contact and air times. The jumping index indicates power. No significant correlation existed between the jumping height and contact time of the lay-up shot jump, the 2 components of the lay-up shot jump index. As a result, jumping height and contact time were found to be mutually independent abilities. The relationships in contact time between the lay-up shot jump to the 1-legged repeated rebound jump and the 2-legged repeated rebound jump were correlated on the same significance levels (p jumping height existed between the 1-legged repeated rebound jump and the lay-up shot jump (p jumping height between the lay-up shot jump and both the 2-legged repeated rebound jump and countermovement jump. The lay-up shot index correlated more strongly to the 1-legged repeated rebound jump index (p jump index (p jump is effective in improving both contact time and jumping height in the lay-up shot jump.

  18. Filtering and control of stochastic jump hybrid systems

    CERN Document Server

    Yao, Xiuming; Zheng, Wei Xing

    2016-01-01

    This book presents recent research work on stochastic jump hybrid systems. Specifically, the considered stochastic jump hybrid systems include Markovian jump Ito stochastic systems, Markovian jump linear-parameter-varying (LPV) systems, Markovian jump singular systems, Markovian jump two-dimensional (2-D) systems, and Markovian jump repeated scalar nonlinear systems. Some sufficient conditions are first established respectively for the stability and performances of those kinds of stochastic jump hybrid systems in terms of solution of linear matrix inequalities (LMIs). Based on the derived analysis conditions, the filtering and control problems are addressed. The book presents up-to-date research developments and novel methodologies on stochastic jump hybrid systems. The contents can be divided into two parts: the first part is focused on robust filter design problem, while the second part is put the emphasis on robust control problem. These methodologies provide a framework for stability and performance analy...

  19. Genetic structure of Bemisia tabaci Med populations from home-range countries, inferred by nuclear and cytoplasmic markers: impact on the distribution of the insecticide resistance genes.

    Science.gov (United States)

    Gauthier, Nathalie; Clouet, Cécile; Perrakis, Andreas; Kapantaidaki, Despoina; Peterschmitt, Michel; Tsagkarakou, Anastasia

    2014-10-01

    Insecticide resistance management in Bemisia tabaci is one of the main issues facing agricultural production today. An extensive survey was undertaken in five Mediterranean countries to examine the resistance status of Med B. tabaci species in its range of geographic origin and the relationship between population genetic structure and the distribution of resistance genes. The investigation combined molecular diagnostic tests, sequence and microsatellite polymorphism studies and monitoring of endosymbionts. High frequencies of pyrethroid (L925I and T929V, VGSC gene) and organophosphate (F331W, ace1 gene) resistance mutations were found in France, Spain and Greece, but not in Morocco or Tunisia. Sequence analyses of the COI gene delineated two closely related mitochondrial groups (Q1 and Q2), which were found either sympatrically (Spain) or separately (France). Only Q1 was observed in Greece, Morocco and Tunisia. Bayesian analyses based on microsatellite loci revealed three geographically delineated genetic groups (France, Spain, Morocco/Greece/Tunisia) and high levels of genetic differentiation even between neighbouring samples. Evidence was also found for hybridisation and asymmetrical gene flow between Q1 and Q2. Med B. tabaci is more diverse and structured than reported so far. On a large geographic scale, resistance is affected by population genetic structure, whereas on a local scale, agricultural practices appear to play a major role. © 2014 Society of Chemical Industry.

  20. Effect of load positioning on the kinematics and kinetics of weighted vertical jumps.

    Science.gov (United States)

    Swinton, Paul A; Stewart, Arthur D; Lloyd, Ray; Agouris, Ioannis; Keogh, Justin W L

    2012-04-01

    One of the most popular exercises for developing lower-body muscular power is the weighted vertical jump. The present study sought to examine the effect of altering the position of the external load on the kinematics and kinetics of the movement. Twenty-nine resistance-trained rugby union athletes performed maximal effort jumps with 0, 20, 40, and 60% of their squat 1 repetition maximum (1RM) with the load positioned (a) on the posterior aspect of the shoulder using a straight barbell and (b) at arms' length using a hexagonal barbell. Kinematic and kinetic variables were calculated through integration of the vertical ground reaction force data using a forward dynamics approach. Performance of the hexagonal barbell jump resulted in significantly (p barbell jump. Significantly (p barbell combined with a load of 20% 1RM compared with all other conditions investigated. The results suggest that weighted vertical jumps should be performed with the external load positioned at arms' length rather than on the shoulder when attempting to improve lower-body muscular performance.

  1. Specific warm-up exercise is the best for vertical countermovement jump in young volleyball players

    Directory of Open Access Journals (Sweden)

    Fernando Nazário de Rezende

    Full Text Available Abstract We evaluated the effect of performing various distinct warm-up exercises on vertical countermovement jump (VCMJ performance. Eight volleyball players (age 15.4 ± 0.5 yrs performed five different warm-up activities (in a counterbalanced, randomized crossover study over five days, at 24-h intervals: stretching (4 × 30 s, 30 s between sets, cycloergometer (5 min at 50 W + 5 min at 100 W, resistance exercise (leg press 45°, 3 × 5 repetitions maximum, 3-min pause between sets, specific vertical jumping (4 × 10 VCMJ, 2-min pause between sets, and no warm-up at all (control condition. Beginning 3 min after their warm-up, the players performed 3 attempts (at intervals of 3 min of VCMJ (on a contact carpet, and each player's best jump was considered in the analysis. All warm-up activities presented higher VCMJ performance (p< 0.05 than the control condition, with the exception of stretching. Vertical jumping revealed a large effect size(0.8 than other interventions. We conclude that in practical terms, vertical jumps are the best warm-up exercise (when applied by itself to acutely improve VCMJ performance in volleyball players, but that other exercises can make a complementary contribution.

  2. Comparison of soil thickness in a zero-order basin in the Oregon Coast Range using a soil probe and electrical resistivity tomography

    Science.gov (United States)

    Morse, Michael S.; Lu, Ning; Godt, Jonathan W.; Revil, André; Coe, Jeffrey A.

    2012-01-01

    Accurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration. One important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding. In this paper, we investigate the direct current (DC) resistivity method as a tool for quickly estimating soil thickness over a steep (33–40°) zero-order basin in the Oregon Coast Range, a landslide prone region. Point measurements throughout the basin showed bedrock depths between 0.55 and 3.2 m. Resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92%. Resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70%. Results from the laboratory measurements and point-depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil-bedrock interface. A decreasing-with-depth resistivity contrast was apparent at the interface in the modeling results. At the field site, three transects were surveyed where coincident ground truth measurements of bedrock depth were available, to test the accuracy of the method. The same decreasing-with-depth resistivity trend that was apparent in the model was also present in the survey data. The resistivity contour of between 1,000 and 2,000 Ωm that marked the top of the contrast was our interpreted bedrock depth in the survey data. Kriged depth-to-bedrock maps were created from both the field-measured ground truth obtained with a soil probe and interpreted depths from the resistivity tomography, and these were compared for accuracy graphically. Depths were interpolated as far as 16.5 m laterally from the resistivity survey lines with root mean squared error (RMSE) = 27 cm between the measured and interpreted depth at those locations. Using several transects and analysis of the subsurface

  3. Kinetics of jump landing in agility dogs.

    Science.gov (United States)

    Pfau, Thilo; Garland de Rivaz, Alison; Brighton, Stephanie; Weller, Renate

    2011-11-01

    A recent survey reported an increased risk of injury in dogs participating in agility, a competitive canine sport involving different jumping activities. The aim of this study was to quantify the kinetic parameters during jump landing for commonly used obstacle types. It was hypothesised that with increasing obstacle height, the vertical force and vertical and accelerative horizontal impulse will increase as a result of a lengthened aerial phase, a more acute landing angle and the need to convert potential into forwards kinetic energy. Simultaneous kinetic and kinematic data were recorded from 11 competition agility dogs jumping over obstacle combinations of different height and inter-obstacle distance. Speed and landing angle of the second of the two consecutive jumps were successfully controlled by obstacle height and distance between obstacles. Statistical analysis showed differences between obstacles for peak vertical force, vertical impulse and accelerative horizontal impulse (increasing values with more acute landing angles). Extremely high peak vertical force was observed in the forelimbs (4.5 times bodyweight) when landing from a hurdle jump at high speed. Further detailed studies into the consequences for internal limb structures are warranted in order to clarify how this might be related to injury. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. A locust-inspired miniature jumping robot.

    Science.gov (United States)

    Zaitsev, Valentin; Gvirsman, Omer; Ben Hanan, Uri; Weiss, Avi; Ayali, Amir; Kosa, Gabor

    2015-11-25

    Unmanned ground vehicles are mostly wheeled, tracked, or legged. These locomotion mechanisms have a limited ability to traverse rough terrain and obstacles that are higher than the robot's center of mass. In order to improve the mobility of small robots it is necessary to expand the variety of their motion gaits. Jumping is one of nature's solutions to the challenge of mobility in difficult terrain. The desert locust is the model for the presented bio-inspired design of a jumping mechanism for a small mobile robot. The basic mechanism is similar to that of the semilunar process in the hind legs of the locust, and is based on the cocking of a torsional spring by wrapping a tendon-like wire around the shaft of a miniature motor. In this study we present the jumping mechanism design, and the manufacturing and performance analysis of two demonstrator prototypes. The most advanced jumping robot demonstrator is power autonomous, weighs 23 gr, and is capable of jumping to a height of 3.35 m, covering a distance of 1.37 m.

  5. Temperature dependence of the electrical resistivity of R6(Fesub(1-x)Mnsub(x))23 compounds in the temperature range 4.2 to 300 K

    International Nuclear Information System (INIS)

    Gratz, E.; Kirchmayr, H.R.

    1976-01-01

    The temperature dependence of the electrical resistivity rho of binary R 6 Mn 23 , R 6 Fe 23 (R=Y,Dy,Ho,Er,Tm) and pseudobinary R 6 (Fesub(1-x)Mnsub(x)) 23 (R=Y,Er,Ho) compounds has been determined by a four-probe measuring technique in the temperature range 4 to 300 K. The binary compounds exhibit a rho prop. T 2 dependence at low temperatures, while above 100 K a negative curvature of the rho-T-curves is observed. These experimental results are discussed on the basis of electron-spin wave scattering in the low temperature range and on the basis of s-d scattering in the high temperature range, taking explicitly into account the temperature dependence of the chemical potentials. The pseudobinary compounds generally exhibit a decreasing resistivity with increasing temperature, combined with a high residual resistivity. These facts are explained by the so-called strong scattering mechanism and the appearance of 'quasilocalized' states. (Auth.)

  6. Characteristics of Integrons and Associated Gene Cassettes in Antibiotic-Resistant Escherichia coli Isolated from Free-Ranging Food Animals in China.

    Science.gov (United States)

    Rehman, Mujeeb Ur; Zhang, Hui; Huang, Shucheng; Iqbal, Muhammad Kashif; Mehmood, Khalid; Luo, Houqiang; Li, Jiakui

    2017-08-01

    We investigated the occurrence of integrons in antibiotic-resistant Escherichia coli strains isolated from free-ranging food animals, including yaks, piglets, and chickens, in China, and characterized the gene cassettes harbored within the integrons. We examined 432 E. coli strains that exhibited resistance to at least one class of antibiotics. Integrase genes and associated gene cassettes were characterized by polymerase chain reaction (PCR) analysis, restriction fragment-length polymorphism, DNA sequencing, conjugation experiments, and plasmid analysis. Twenty-nine (6.7%) integrons were amplified from the 432 antimicrobial-resistant (AMR) isolates evaluated. Specifically, class 1 and 2 integrons were detected in 26 (6%) and 3 (0.7%) strains, respectively. Meanwhile, 6 different gene cassettes, dfrA1, dfr12, aadA1, aadA2, sat1, and orfF, were detected within 6 variable regions (VRs), of which the dfrA1 + aadA1 array was the most common, identified in 12 of 26 class 1 integrons (46.1%). Meanwhile, only one class 2 integron contained a cassette, and the remaining two contained undetermined VRs. Finally, a conjugation assay confirmed the transfer of 4 different types of class 1 integrons into recipient strains, with plasmid sizes ranging from 20 to 30 kb. This is the first report examining the baseline AMR characteristics of E. coli within an extensive farming system of livestock animals in China. Given that integrons were detected in >6% of resistant E. coli strains, precautionary measures are required to prevent the spread of mobile genetic resistance determinants in food animals and monitor their emergence. © 2017 Institute of Food Technologists®.

  7. Serious ski jumping injuries in Norway.

    Science.gov (United States)

    Wester, K

    1985-01-01

    Injuries caused by ski jumping have been poorly investigated. Among approximately 2,200 licensed jumpers in Norway, there occurred at least 12 injuries with a permanent medical disability of greater than or equal to 10%. The risk of being seriously injured is approximately 5% in a 5 year period (1977 to 1981); it is higher in the age group 15 to 17 years. Seven injuries were very serious [four central nervous system (CNS) lesions, two leg amputations, and one blindness of one eye], and five were less serious (sequelae to fractures of the lower extremities). The first jump of the day is particularly dangerous, and so is the beginning and end of the season. It seems dangerous to use more than one standard heel block. Poor preparation of the jump may have contributed to the accidents. Based on the findings, several prophylactic measures are suggested.

  8. Salmon jumping: behavior, kinematics and optimal conditions, with possible implications for fish passageway design

    International Nuclear Information System (INIS)

    Lauritzen, D V; Jordan, L K; Gordon, M S; Hertel, F S

    2010-01-01

    Behavioral and kinematic properties and capacities of wild migratory salmonid fishes swimming upstream and jumping up waterfalls generally have played only minor roles in the design and construction of passageways intended to help these fishes get past dams and other human-made obstacles blocking their movements. This paper reports the results of an experimental study of relevant behavioral and kinematic properties of adult kokanee salmon (Oncorhynchus nerka) jumping up waterfalls as they migrate upstream. We used a portable, adjustable apparatus to study in the field fish responding to artificial waterfalls under a range of flow conditions. We observed fish under conditions of varying water flow rates, pool depths, fall heights and fall angles. We analyzed digital video recordings of their behaviors. Kokanee salmon spontaneously jump up waterfalls within a relatively narrow range of conditions, including low flow speeds, near vertical angles and pool depth to fall height ratios near 1.0. Preferred values for each parameter are, to some extent, dependent on other parameters. In contrast to previous misconceptions, jumping behavior is initiated by running S-start accelerations from beneath the boils formed in the plunge pools below waterfalls, as opposed to C-start standing jumps from the surface. S-starts are immediately followed by burst swimming to the point of takeoff at the surface. These results can contribute to an improved basis for developing designs of fish passageways that may ultimately make them more effective and efficient.

  9. Inverse dynamic modelling of jumping in the red-legged running frog,Kassina maculata.

    Science.gov (United States)

    Porro, Laura B; Collings, Amber J; Eberhard, Enrico A; Chadwick, Kyle P; Richards, Christopher T

    2017-05-15

    Although the red-legged running frog, Kassina maculata , is secondarily a walker/runner, it retains the capacity for multiple locomotor modes, including jumping at a wide range of angles (nearly 70 deg). Using simultaneous hind limb kinematics and single-foot ground reaction forces, we performed inverse dynamics analyses to calculate moment arms and torques about the hind limb joints during jumping at different angles in K. maculata. We show that forward thrust is generated primarily at the hip and ankle, while body elevation is primarily driven by the ankle. Steeper jumps are achieved by increased thrust at the hip and ankle and greater downward rotation of the distal limb segments. Because of its proximity to the GRF vector, knee posture appears to be important in controlling torque directions about this joint and, potentially, torque magnitudes at more distal joints. Other factors correlated with higher jump angles include increased body angle in the preparatory phase, faster joint openings and increased joint excursion, higher ventrally directed force, and greater acceleration and velocity. Finally, we demonstrate that jumping performance in K. maculata does not appear to be compromised by presumed adaptation to walking/running. Our results provide new insights into how frogs engage in a wide range of locomotor behaviours and the multi-functionality of anuran limbs. © 2017. Published by The Company of Biologists Ltd.

  10. Recent Advancements in Lightning Jump Algorithm Work

    Science.gov (United States)

    Schultz, Christopher J.; Petersen, Walter A.; Carey, Lawrence D.

    2010-01-01

    In the past year, the primary objectives were to show the usefulness of total lightning as compared to traditional cloud-to-ground (CG) networks, test the lightning jump algorithm configurations in other regions of the country, increase the number of thunderstorms within our thunderstorm database, and to pinpoint environments that could prove difficult for any lightning jump configuration. A total of 561 thunderstorms have been examined in the past year (409 non-severe, 152 severe) from four regions of the country (North Alabama, Washington D.C., High Plains of CO/KS, and Oklahoma). Results continue to indicate that the 2 lightning jump algorithm configuration holds the most promise in terms of prospective operational lightning jump algorithms, with a probability of detection (POD) at 81%, a false alarm rate (FAR) of 45%, a critical success index (CSI) of 49% and a Heidke Skill Score (HSS) of 0.66. The second best performing algorithm configuration was the Threshold 4 algorithm, which had a POD of 72%, FAR of 51%, a CSI of 41% and an HSS of 0.58. Because a more complex algorithm configuration shows the most promise in terms of prospective operational lightning jump algorithms, accurate thunderstorm cell tracking work must be undertaken to track lightning trends on an individual thunderstorm basis over time. While these numbers for the 2 configuration are impressive, the algorithm does have its weaknesses. Specifically, low-topped and tropical cyclone thunderstorm environments are present issues for the 2 lightning jump algorithm, because of the suppressed vertical depth impact on overall flash counts (i.e., a relative dearth in lightning). For example, in a sample of 120 thunderstorms from northern Alabama that contained 72 missed events by the 2 algorithm 36% of the misses were associated with these two environments (17 storms).

  11. Variation in phenotype for resistance to Phytophthora ramorum in a range of species and cultivars of the genus Viburnum

    Science.gov (United States)

    Niklaus J. Grunwald; E. Anne Davis; Robert G. Linderman

    2006-01-01

    Phytophthora ramorum is a recently introduced plant pathogen causing a range of diseases including sudden oak death, Ramorum shoot dieback and Ramorum blight (Rizzo and others 2002, 2004; Werres and others 2001). P. ramorum also attacks several nursery crops including viburnum and rhododendron (Werres and others 2001). Since its...

  12. A Biomechanical Comparison Among Three Kinds of Rebound-Type Jumps in Female Collegiate Athletes.

    Science.gov (United States)

    Nariai, Miki; Yoshida, Naruto; Imai, Atsushi; Ae, Kazumichi; Ogaki, Ryo; Suhara, Hirokazu; Shiraki, Hitoshi

    2017-08-01

    Single-legged drop jumps (SDJ), single-legged repetitive jumps (SRJ), and single-legged side hops (SSH) are often used as plyometric training and functional performance tests. Differences in the kinetics and kinematic characteristics of lower extremity joints during these jumps are unclear. The purpose of this study was to investigate the joint motion and mechanical work of the takeoff leg from foot contact to foot-off during SDJ, SRJ, and SSH in the sagittal and frontal planes in female athletes. It was hypothesized that the joint motion and mechanical work of the lower extremity joints during the SDJ and SRJ would be larger than the SSH in the sagittal plane, those during the SSH would be larger than the SDJ and SRJ in the frontal plane, and during SRJ would be larger than SDJ. Cross-sectional study. Seventeen female collegiate athletes participated and performed the SDJ (0.15-m box height), and SRJ and SSH (by crossing two lines 0.3 m apart). Three-dimensional coordinate data and ground reaction forces were collected. Contact time, jump height, jump index (i.e., the jump height divided by the contact time) of the SDJ and SRJ, and the total times of the SSH were calculated. Range of motion (ROM) from touchdown to the lowest center of mass, and the positive and negative (mechanical) work from touchdown to foot-off were analyzed. There were no significant differences in jump performance variables. Compared to the SSH, the SDJ and SRJ had significantly larger ankle and knee ROM and positive and negative work at the lower extremity joints, except for positive work at the hip joint, in the sagittal plane (p SSH had a significantly larger ankle ROM and positive work at the knee joint in the frontal plane (p < 0.05). Compared to the SDJ, the SRJ had a significantly larger ROM and negative work at each lower extremity joint in the frontal plane (p < 0.05). Although there were no significant differences in the jump performance variables, different

  13. ELMs, strike point jumps and SOL currents

    International Nuclear Information System (INIS)

    Solano, Emilia R.; Jachmich, S.; Villone, F.; Hawkes, N.; Guenther, K.; Korotkov, A.; Stamp, M.; Andrew, P.; Conboy, J.; Mattews, G.F.; Corre, Y.; Loarte, A.; Pitts, R.A.; Cenedese, A.; Kempenaars, M.; Bolzonella, T.; Rachlew, E.

    2005-01-01

    Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associated with fragile equilibria and separatrix instabilities: previously closed field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. This model could explain experimental observations of sudden jumps and shifts in strike point positions. Novel instability mechanisms are discussed to explain the large transient jumps observed in the strike point position: positive X-point instability, due to positive toroidal current density at the X-point and diamagnetic instability, due to negative inboard toroidal current density. (author)

  14. Stock jumps: Analyzing traditional and behavioral perspectives

    Directory of Open Access Journals (Sweden)

    Francesco Corea

    2015-07-01

    Full Text Available Our aim is to define the concept of stock jumps from a practitioner’s perspective and to give an insightful overview of the topic. We provide different technical and practical definitions from distinct points of view: mathematical, risk managerial, trading and investing. We verify the robustness of some common stylised facts for three major stock indices, and we derive an approximated jumps distribution. We finally provide some innovative insights from a behavioral perspective, and how to account for behavioral biases in this context.

  15. Methodological concerns for determining power output in the jump squat.

    Science.gov (United States)

    Cormie, Prue; Deane, Russell; McBride, Jeffrey M

    2007-05-01

    The purpose of this study was to investigate the validity of power measurement techniques during the jump squat (JS) utilizing various combinations of a force plate and linear position transducer (LPT) devices. Nine men with at least 6 months of prior resistance training experience participated in this acute investigation. One repetition maximums (1RM) in the squat were determined, followed by JS testing under 2 loading conditions (30% of 1RM [JS30] and 90% of 1RM [JS90]). Three different techniques were used simultaneously in data collection: (a) 1 linear position transducer (1-LPT); (b) 1 linear position transducer and a force plate (1-LPT + FP); and (c) 2 linear position transducers and a force place (2-LPT + FP). Vertical velocity-, force-, and power-time curves were calculated for each lift using these methodologies and were compared. Peak force and peak power were overestimated by 1-LPT in both JS30 and JS90 compared with 2-LPT + FP and 1-LPT + FP (p squat varies according to the measurement technique utilized. The 1-LPT methodology is not a valid means of determining power output in the jump squat. Furthermore, the 1-LPT + FP method may not accurately represent power output in free weight movements that involve a significant amount of horizontal motion.

  16. Resistance of (Fe, Ni)/sub 3/V long-range-ordered alloys to neutron and ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Braski, D.N.

    1981-01-01

    A series of (Fe, Ni)/sub 3/V long-range-ordered alloys were irradiated with neutrons in the Oak Ridge Research Reactor (ORR) and with 4 MeV Ni ions at temperatures above 250/sup 0/C. The displacement damage levels for the two irradiations were 3.8 and 70 dpa, and the helium levels were 29 and 560 at. ppM, respectively. Irradiation in ORR generally increased the yield strength and lowered the ductility of an LRO alloy, but produced relatively little swelling. The LRO alloys retained their long-range order after ion irradiation below the critical ordering temperature, T/sub c/, and exhibited low swelling. Above T/sub c/ the alloys were disordered and showed greater swelling. Adjustment of alloy composition to prevent sigma phase formation reduced swelling.

  17. First report of a multidrug-resistant Klebsiella pneumoniae of sequence type 11 causing sepsis in a free-ranging beaver (Castor fiber).

    Science.gov (United States)

    Pilo, Paola; Vogt, Debora; Origgi, Francesco C; Endimiani, Andrea; Peterson, Susanne; Perreten, Vincent

    2015-04-01

    Klebsiella pneumoniae of sequence type (ST) 11 is a hyper-epidemic nosocomial clone spreading worldwide among humans and also emerging in pets. In this report, we describe a clinical case of fatal sepsis due to this multidrug-resistant (MDR) pathogen in a Eurasian beaver. The isolate showed resistance to six different classes of antimicrobials including third generation cephalosporins and fluoroquinolones. This is the first report describing the detection of a MDR K. pneumoniae ST11 in a free-ranging animal. Our finding highlights the potential for environmental dissemination of hyper-epidemic clones of K. pneumoniae and possible spread in wildlife and cause epizootics. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Biomechanical Analysis of the Jump Shot in Basketball

    OpenAIRE

    Struzik Artur; Pietraszewski Bogdan; Zawadzki Jerzy

    2014-01-01

    Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can util...

  19. Cube Handling In Backgammon Money Games Under a Jump Model

    OpenAIRE

    Higgins, Mark G.

    2012-01-01

    A variation on Janowski's cubeful equity model is proposed for cube handling in backgammon money games. Instead of approximating the cubeful take point as an interpolation between the dead and live cube limits, a new model is developed where the cubeless probability of win evolves through a series of random jumps instead of continuous diffusion. Each jump is drawn from a distribution with zero mean and an expected absolute jump size called the "jump volatility" that can be a function of game ...

  20. Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant.

    Science.gov (United States)

    Jensen, Kyle C; Hair, Bryan B; Wienclaw, Trevor M; Murdock, Mark H; Hatch, Jacob B; Trent, Aaron T; White, Tyler D; Haskell, Kyler J; Berges, Bradford K

    2015-01-01

    Staphylococcus aureus (SA) is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA) isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA may achieve broad resistance to vancomycin in the near future. New MRSA treatments are clearly needed. Bacteriophages (phages) are viruses that infect bacteria, commonly resulting in death of the host bacterial cell. Phage therapy entails the use of phage to treat or prevent bacterial infections. In this study, 12 phages were isolated that can replicate in human SA and/or MRSA isolates as a potential way to control these infections. 5 phage were discovered through mitomycin C induction of prophage and 7 others as extracellular viruses. Primary SA strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates by spot testing. Primary isolates were tested for susceptibility to oxacillin in order to determine which were MRSA. Experiments were performed to assess the host range and killing potential of newly discovered phage, and significant reductions in bacterial load were detected. We explored the utility of some phage to decontaminate fomites (glass and cloth) and found a significant reduction in colony forming units of MRSA following phage treatment, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.

  1. Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant.

    Directory of Open Access Journals (Sweden)

    Kyle C Jensen

    Full Text Available Staphylococcus aureus (SA is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA may achieve broad resistance to vancomycin in the near future. New MRSA treatments are clearly needed. Bacteriophages (phages are viruses that infect bacteria, commonly resulting in death of the host bacterial cell. Phage therapy entails the use of phage to treat or prevent bacterial infections. In this study, 12 phages were isolated that can replicate in human SA and/or MRSA isolates as a potential way to control these infections. 5 phage were discovered through mitomycin C induction of prophage and 7 others as extracellular viruses. Primary SA strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates by spot testing. Primary isolates were tested for susceptibility to oxacillin in order to determine which were MRSA. Experiments were performed to assess the host range and killing potential of newly discovered phage, and significant reductions in bacterial load were detected. We explored the utility of some phage to decontaminate fomites (glass and cloth and found a significant reduction in colony forming units of MRSA following phage treatment, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.

  2. Safety assessment of jumps in ski racing.

    Science.gov (United States)

    Schindelwig, K; Reichl, W; Kaps, P; Mössner, M; Nachbauer, W

    2015-12-01

    The influence of important parameters on the flight trajectory for jumps in downhill World Cup races was investigated. To quantify the impact injury risk at landing, the parameter equivalent landing height (ELH) was introduced, which considered a variable slope inclination during the landing movement. Altogether, 145 runs at four different jumps in World Cup races and trainings were recorded and analyzed. A simulation model was developed to predict the flight phase of the skier. Drag and lift areas were selected by parameter identification to fit the simulation trajectory to the two-dimensional data from the video analysis. The maximum values of the ELH which can be absorbed with muscle force was taken from the study of Minetti et al. for elite female and male ski racers. A sensitivity analysis based on the four jumps showed that ELH is mainly influenced by takeoff angle, takeoff speed, and the steepness of the landing surface. With the help of the developed simulation software, it should be possible to predict the ELH for jumps in advance. In case of an excessive ELH, improvements can be made by changing the takeoff inclination or the approach speed. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Costs and benefits of larval jumping behaviour of Bathyplectes anurus

    Science.gov (United States)

    Saeki, Yoriko; Tani, Soichiro; Fukuda, Katsuto; Iwase, Shun-ichiro; Sugawara, Yuma; Tuda, Midori; Takagi, Masami

    2016-02-01

    Bathyplectes anurus, a parasitoid of the alfalfa weevils, forms a cocoon in the late larval stage and exhibits jumping behaviour. Adaptive significance and costs of the cocoon jumping have not been thoroughly studied. We hypothesised that jumping has the fitness benefits of enabling habitat selection by avoiding unfavourable environments. We conducted laboratory experiments, which demonstrated that jumping frequencies increased in the presence of light, with greater magnitudes of temperature increase and at lower relative humidity. In addition, when B. anurus individuals were allowed to freely jump in an arena with a light gradient, more cocoons were found in the shady area, suggesting microhabitat selection. In a field experiment, mortality of cocoons placed in the sun was significantly higher than for cocoons placed in the shade. B. anurus cocoons respond to environmental stress by jumping, resulting in habitat selection. In the presence of potential predators (ants), jumping frequencies were higher than in the control (no ant) arenas, though jumping frequencies decreased after direct contact with the predators. Body mass of B. anurus cocoons induced to jump significantly decreased over time than cocoons that did not jump, suggesting a cost to jumping. We discuss the benefits and costs of jumping behaviour and potential evolutionary advantages of this peculiar trait, which is present in a limited number of species.

  4. Explanation of the bilateral deficit in human vertical squat jumping

    NARCIS (Netherlands)

    Bobbert, M.F.; de Graaf, W.W.; Jonk, J.N.; Casius, L.J.R.

    2006-01-01

    In the literature, it has been reported that the mechanical output per leg is less in two-leg jumps than in one-leg jumps. This so-called bilateral deficit has been attributed to a reduced neural drive to muscles in two-leg jumps. The purpose of the present study was to investigate the possible

  5. Vorticity determination in a hydraulic jump by application of method ...

    African Journals Online (AJOL)

    The method of characteristics for solving systems of partial differential equations coupled with jump conditions is used in analysing flow downstream of a hydraulic jump instead of the normal analytical approach adopted in Hornung [1]. It is shown that the method of characteristics together with the jump conditions can ...

  6. EXPERIMENTAL STUDY OF HYDRAULIC JUMP EVOLVING IN AN U

    African Journals Online (AJOL)

    hydraulic jump threshold, moving in a channel profile 'U' bottom rough, linking the different characteristics of ... Key words: hydraulic jump, channel profile 'U', rough bottom canal, roughness. 1. INTRODUCTION. L'étude ...... [7] Rajartnam N. Hydraulic jumps on rough beds, Transaction of the engineering institute of Canada.

  7. THE ACUTE EFFECTS OF BACK SQUATS ON VERTICAL JUMP PERFORMANCE IN MEN AND WOMEN

    Directory of Open Access Journals (Sweden)

    Gavin L. Moir

    2010-06-01

    Full Text Available The aim of the present study was to investigate the acute effects of performing back squats on subsequent performance during a series of vertical jumps in men and women. Twelve men and 12 women were tested on three separate occasions, the first of which was used to determine their 1-repetition maximum (1-RM parallel back squat. Following this, subjects performed a potentiation and a control treatment in a counterbalanced order. The potentiation treatment culminated with subjects performing parallel back squats with a load equivalent to 70% 1- RM for three repetitions, following which they performed one countermovement vertical jump (CMJ for maximal height every three minutes for a total of 10 jumps. During the control treatment, subjects performed only the CMJs. Jump height (JH and vertical stiffness (VStiff were calculated for each jump from the vertical force signal recorded from a force platform. There were no significant changes in JH or VStiff following the treatments and no significant differences in the responses between men and women (p > 0.05. Correlations between normalized 1-RM back squat load and the absolute change in JH and VStiff were small to moderate for both men and women, with most correlations being negative. Large variations in response to the back squats were noted in both men and women. The use of resistance exercises performed prior to a series of vertical jumps can result in improvements in performance in certain individuals, although the gains tend to be small and dependent upon the mechanical variable measured. There does not seem to be any differences between men and women in the response to dynamic potentiation protocols

  8. Measurement of the dynamics in ski jumping using a wearable inertial sensor-based system.

    Science.gov (United States)

    Chardonnens, Julien; Favre, Julien; Cuendet, Florian; Gremion, Gérald; Aminian, Kamiar

    2014-01-01

    Dynamics is a central aspect of ski jumping, particularly during take-off and stable flight. Currently, measurement systems able to measure ski jumping dynamics (e.g. 3D cameras, force plates) are complex and only available in few research centres worldwide. This study proposes a method to determine dynamics using a wearable inertial sensor-based system which can be used routinely on any ski jumping hill. The system automatically calculates characteristic dynamic parameters during take-off (position and velocity of the centre of mass perpendicular to the table, force acting on the centre of mass perpendicular to the table and somersault angular velocity) and stable flight (total aerodynamic force). Furthermore, the acceleration of the ski perpendicular to the table was quantified to characterise the skis lift at take-off. The system was tested with two groups of 11 athletes with different jump distances. The force acting on the centre of mass, acceleration of the ski perpendicular to the table, somersault angular velocity and total aerodynamic force were different between groups and correlated with the jump distances. Furthermore, all dynamic parameters were within the range of prior studies based on stationary measurement systems, except for the centre of mass mean force which was slightly lower.

  9. Jump distance of dance landings influencing internal joint forces: I. Axial forces.

    Science.gov (United States)

    Simpson, K J; Kanter, L

    1997-07-01

    Knowledge of the magnitude and rate of applying axial forces (AF) during actual dance movements is necessary for understanding the etiology of chronic injuries and osteoarthritis. The purpose of this study was to investigate the effect of jumping distance on component ankle and knee joint AFs generated during the landing phase of traveling jumps. Six female dancers performed 10 jumps each at 30, 60, and 90% maximum jump distance (JD) and 15 jumps ranging from 35 to 100% JD. A sagittal view of the right leg landing onto a force platform was filmed. Greater ground reaction force maxima, knee flexion, knee and ankle flexion velocity, tibial landing angle, net ankle and knee joint moment maxima, ankle and knee joint reaction AFs, and quadriceps AFs (QuadAF) peak magnitudes and rates of AF application (dFmax/dt) were observed (P JD. The QuadAF was a more important determinant of knee AF than joint reaction AF. Increased quadriceps force was useful for accommodating impact forces but served to increase its contribution to Knee AF, particularly during the later portion of the impact phase. High impact situations create significant magnitudes (e.g., 14 BW) and dFmax/dt of muscle AFs which could contribute to excessive joint wear.

  10. Jump distance of dance landings influencing internal joint forces: II. Shear forces.

    Science.gov (United States)

    Simpson, K J; Pettit, M

    1997-07-01

    Little is known about shear loading patterns during dance movements. The purpose of the study was to investigate the effect of jumping distance (JD) on contributors of ankle and knee shear forces (SF) generated during the landing phase of traveling jumps. Six female dancers performed 10 trials each at 30, 60, and 90% maximum jump distance (JD) and 15 jumps ranging from 35 to 100% JD. A sagittal view of the right leg landing onto a force platform was filmed using a high-speed cine camera. Greater ankle and knee joint reaction shear forces (JRSF) and quadriceps SF (QuadSF) were observed (P JD. Although the triceps surae SF (TriSurSF) also increased at greater JD for all but one participant, the effect on minimizing the increase in the ankle SF was minor. The peak QuadSF magnitude and rate of loading were always greater than the corresponding knee JRSF variables. However, the increased QuadSF that occurred at longer jumps led to increased knee SF for only half of the participants.

  11. Measurement errors when estimating the vertical jump height with flight time using photocell devices: the example of Optojump.

    Science.gov (United States)

    Attia, A; Dhahbi, W; Chaouachi, A; Padulo, J; Wong, D P; Chamari, K

    2017-03-01

    Common methods to estimate vertical jump height (VJH) are based on the measurements of flight time (FT) or vertical reaction force. This study aimed to assess the measurement errors when estimating the VJH with flight time using photocell devices in comparison with the gold standard jump height measured by a force plate (FP). The second purpose was to determine the intrinsic reliability of the Optojump photoelectric cells in estimating VJH. For this aim, 20 subjects (age: 22.50±1.24 years) performed maximal vertical jumps in three modalities in randomized order: the squat jump (SJ), counter-movement jump (CMJ), and CMJ with arm swing (CMJarm). Each trial was simultaneously recorded by the FP and Optojump devices. High intra-class correlation coefficients (ICCs) for validity (0.98-0.99) and low limits of agreement (less than 1.4 cm) were found; even a systematic difference in jump height was consistently observed between FT and double integration of force methods (-31% to -27%; p1.2). Intra-session reliability of Optojump was excellent, with ICCs ranging from 0.98 to 0.99, low coefficients of variation (3.98%), and low standard errors of measurement (0.8 cm). It was concluded that there was a high correlation between the two methods to estimate the vertical jump height, but the FT method cannot replace the gold standard, due to the large systematic bias. According to our results, the equations of each of the three jump modalities were presented in order to obtain a better estimation of the jump height.

  12. Multilevel resistive switching in TiO2/Al2O3 bilayers at low temperature

    Science.gov (United States)

    Andreeva, N.; Ivanov, A.; Petrov, A.

    2018-02-01

    We report an approach to design a metal-insulator-metal (MIM) structure exhibiting multilevel resistive switching. Toward this end, two oxide layers (TiO2 and Al2O3) were combined to form a bilayer structure. MIM structures demonstrate stable bipolar switching relative to the resistive state determined by the bias voltage. The resistive state of such bilayer structures can be electrically tuned over seven orders of magnitude. The resistance is determined by the concentration of oxygen vacancies in the active layer of Al2O3. To elucidate a possible mechanism for resistive switching, structural studies and measurements have been made in the temperature range 50-295 K. Resistive switching occurs over the entire temperature range, which assumes the electronic character of the process in the Al2O3 layer. The experimental results indicate that hopping transport with variable-length jumps is the most probable transport mechanism in these MIM structures.

  13. Experimental study of the positive leader velocity as a function of the current in the initial and final-jump phases of a spark discharge

    International Nuclear Information System (INIS)

    Andreev, A. G.; Bazelyan, E. M.; Bulatov, M. U.; Kuzhekin, I. P.; Makalsky, L. M.; Sukharevskij, D. I.; Syssoev, V. S.

    2008-01-01

    A positive leader in air at gap lengths of up to 8 m was studied experimentally on an open experimental stand. The voltage source was a 6-MV pulsed voltage generator or an artificial charged aerosol cloud. The dependence of the leader velocity on the current in the range 0.2-8 A was determined by simultaneously recording the optical picture and electric parameters of the discharge. Particular attention was paid to the final-jump phase of the discharge, when the gap was completely bridged by the streamer zone of the leader. It is shown that the character of the dependence of the leader velocity on the current in this phase remains unchanged; hence, the final-jump phase can be used in experiments in which the current has to be varied within a wide range. For this purpose, one can use a damping resistance, which is inefficient in the initial phase. The parameters of the power-law dependence of the leader velocity on the current at currents of a few amperes are established reliably. It is found that the power-law dependence with constant parameters is inapplicable to calculate the leader velocity at currents of about 0.1 A, which correspond to the lower limit of the leader viability.

  14. Toxicity and population structure of the Rough-Skinned Newt (Taricha granulosa) outside the range of an arms race with resistant predators.

    Science.gov (United States)

    Hague, Michael T J; Avila, Leleña A; Hanifin, Charles T; Snedden, W Andrew; Stokes, Amber N; Brodie, Edmund D; Brodie, Edmund D

    2016-05-01

    Species interactions, and their fitness consequences, vary across the geographic range of a coevolutionary relationship. This spatial heterogeneity in reciprocal selection is predicted to generate a geographic mosaic of local adaptation, wherein coevolutionary traits are phenotypically variable from one location to the next. Under this framework, allopatric populations should lack variation in coevolutionary traits due to the absence of reciprocal selection. We examine phenotypic variation in tetrodotoxin (TTX) toxicity of the Rough-Skinned Newt (Taricha granulosa) in regions of allopatry with its TTX-resistant predator, the Common Garter Snake (Thamnophis sirtalis). In sympatry, geographic patterns of phenotypic exaggeration in toxicity and toxin-resistance are closely correlated in prey and predator, implying that reciprocal selection drives phenotypic variation in coevolutionary traits. Therefore, in allopatry with TTX-resistant predators, we expect to find uniformly low levels of newt toxicity. We characterized TTX toxicity in northwestern North America, including the Alaskan panhandle where Ta. granulosa occur in allopatry with Th. sirtalis. First, we used microsatellite markers to estimate population genetic structure and determine if any phenotypic variation in toxicity might be explained by historical divergence. We found northern populations of Ta. granulosa generally lacked population structure in a pattern consistent with northern range expansion after the Pleistocene. Next, we chose a cluster of sites in Alaska, which uniformly lacked genetic divergence, to test for phenotypic divergence in toxicity. As predicted, overall levels of newt toxicity were low; however, we also detected unexpected among- and within-population variation in toxicity. Most notably, a small number of individuals contained large doses of TTX that rival means of toxic populations in sympatry with Th. sirtalis. Phenotypic variation in toxicity, despite limited neutral genetic

  15. Biomechanical analysis of the jump shot in basketball.

    Science.gov (United States)

    Struzik, Artur; Pietraszewski, Bogdan; Zawadzki, Jerzy

    2014-09-29

    Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player's jumping ability.

  16. Biomechanical Analysis of the Jump Shot in Basketball

    Directory of Open Access Journals (Sweden)

    Struzik Artur

    2014-10-01

    Full Text Available Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability

  17. The effect of a 3-month prevention program on the jump-landing technique in basketball: a randomized controlled trial.

    Science.gov (United States)

    Aerts, Inne; Cumps, Elke; Verhagen, Evert; Wuyts, Bram; Van De Gucht, Sam; Meeusen, Romain

    2015-02-01

    In jump-landing sports, the injury mechanism that most frequently results in an injury is the jump-landing movement. Influencing the movement patterns and biomechanical predisposing factors are supposed to decrease injury occurrence. To evaluate the influence of a 3-mo coach-supervised jump-landing prevention program on jump-landing technique using the jump-landing scoring (JLS) system. Randomized controlled trial. On-field. 116 athletes age 15-41 y, with 63 athletes in the control group and 53 athletes in the intervention group. The intervention program in this randomized control trial was administered at the start of the basketball season 2010-11. The jump-landing training program, supervised by the athletic trainers, was performed for a period of 3 mo. The jump-landing technique was determined by registering the jump-landing technique of all athletes with the JLS system, pre- and postintervention. After the prevention program, the athletes of the male and female intervention groups landed with a significantly less erect position than those in the control groups (P < .05). This was presented by a significant improvement in maximal hip flexion, maximal knee flexion, hip active range of motion, and knee active range of motion. Another important finding was that postintervention, knee valgus during landing diminished significantly (P < .05) in the female intervention group compared with their control group. Furthermore, the male intervention group significantly improved (P < .05) the scores of the JLS system from pre- to postintervention. Malalignments such as valgus position and insufficient knee flexion and hip flexion, previously identified as possible risk factors for lower-extremity injuries, improved significantly after the completion of the prevention program. The JLS system can help in identifying these malalignments. Therapy, prevention, level 1b.

  18. THE INFLUENCE OF MUSICAL CADENCE INTO AQUATIC JUMPING JACKS KINEMATICS

    Directory of Open Access Journals (Sweden)

    Mário J. Costa

    2011-12-01

    Full Text Available The aim of this study was to analyze the relationships between the head-out aquatic exercise "Jumping jacks" kinematics and the musical cadence in healthy and fit subjects. Five young women, with at least one year of experience conducting head- out aquatic programs were videotaped in the frontal plane, with a pair of cameras providing a double projection (above and below the water surface. Subjects performed an incremental protocol of five bouts (120 b·min-1, 135 b·min-1, 150 b·min-1, 165 b·min-1 and 180 b·min-1 with 16 full cycles of the "Jumping jacks" exercise. Data processing and calculation of upper limbs' (i.e. hands, lower limbs' (i.e. feet and center of mass' 2D linear velocity and displacement were computed with the software Ariel Performance Analysis System and applying the 2D-DLT algorithm. Subjects decreased the cycle period during the incremental protocol. Significant and negative relationships with the musical cadence were verified for the center of mass and upper limbs vertical displacement. On the other hand, for the lower limbs lateral velocity, a significant and positive relationship was observed. It is concluded that expert and fit subjects increase the lower limb's velocity to maintain the range of motion, while the upper limb's displacement is reduced to coupe the music cadence.

  19. Differences in take-off leg kinetics between horizontal and vertical single-leg rebound jumps.

    Science.gov (United States)

    Kariyama, Yasushi; Hobara, Hiroaki; Zushi, Koji

    2017-06-01

    This study aimed to clarify the differences between the horizontal single-leg rebound jump (HJ) and vertical single-leg rebound jump (VJ) in terms of three-dimensional joint kinetics for the take-off leg, while focusing on frontal and transverse plane movements. Eleven male track and field athletes performed HJ and VJ. Kinematic and kinetic data were calculated using data recorded with a motion capture system and force platforms. The hip abduction torque, trunk lateral flexion torque (flexion for the swing-leg side), hip external and internal torque, trunk rotational torque, and the powers associated with these torques were larger when performing HJ because of resistance to the impact ground reaction force and because of pelvic and posture control. Pelvic rotation was noted in HJ, and this was controlled not only by the hip and trunk joint torque from the transverse plane but also by the hip abduction torque. Therefore, hip and trunk joint kinetics in the frontal and transverse plane play an important role in a single-leg jump, regardless of the jumping direction, and may also play a more important role in HJ than in VJ.

  20. The Effect of an Altitude Training Camp on Swimming Start Time and Loaded Squat Jump Performance.

    Directory of Open Access Journals (Sweden)

    Amador García-Ramos

    Full Text Available This study evaluated the influence of an altitude training (AT camp on swimming start time and loaded squat jump performance. To accomplish this goal, 13 international swimmers (8 women, 5 men were allocated to both the control (Sea Level Training, SLT and experimental conditions (AT, 2320 m above sea level that were separated by a one year period. All tests (15 m freestyle swimming start and loaded squat jumps with additional loads of 25%, 50%, 75%, and 100% of swimmers' body weight were performed before and after a concurrent 3-week strength and endurance training program prescribed by the national coach. Following the SLT camp, significant impairments in swimming start times to 10 (+3.1% and 15 m (+4.0% were observed (P 0.05. Trivial changes in peak velocity were obtained during the loaded squat jump after both training periods (effect sizes: < 0.20. Based on these results we can conclude that a traditional training high-living high strategy concurrent training of 3 weeks does not adversely affect swimming start time and loaded squat jump performance in high level swimmers, but further studies are necessary to assess the effectiveness of power-oriented resistance training in the development of explosive actions.

  1. The Effect of an Altitude Training Camp on Swimming Start Time and Loaded Squat Jump Performance.

    Science.gov (United States)

    García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Calderón, Carmen; Bonitch-Góngora, Juan; Tomazin, Katja; Strumbelj, Boro; Strojnik, Vojko; Feriche, Belén

    2016-01-01

    This study evaluated the influence of an altitude training (AT) camp on swimming start time and loaded squat jump performance. To accomplish this goal, 13 international swimmers (8 women, 5 men) were allocated to both the control (Sea Level Training, SLT) and experimental conditions (AT, 2320 m above sea level) that were separated by a one year period. All tests (15 m freestyle swimming start and loaded squat jumps with additional loads of 25%, 50%, 75%, and 100% of swimmers' body weight) were performed before and after a concurrent 3-week strength and endurance training program prescribed by the national coach. Following the SLT camp, significant impairments in swimming start times to 10 (+3.1%) and 15 m (+4.0%) were observed (P 0.05). Trivial changes in peak velocity were obtained during the loaded squat jump after both training periods (effect sizes: training high-living high strategy concurrent training of 3 weeks does not adversely affect swimming start time and loaded squat jump performance in high level swimmers, but further studies are necessary to assess the effectiveness of power-oriented resistance training in the development of explosive actions.

  2. Option Panels in Pure-Jump Settings

    DEFF Research Database (Denmark)

    Andersen, Torben Gustav; Fusari, Nicola; Todorov, Viktor

    and maturities available across observation times. We consider the asymptotic setting in which the cross-sectional dimension of the panel increases to infinity while its time span remains fixed. The information set is further augmented with high-frequency data on the underlying asset. Given a parametric......We develop parametric inference procedures for large panels of noisy option data in the setting where the underlying process is of pure-jump type, i.e., evolve only through a sequence of jumps. The panel consists of options written on the underlying asset with a (different) set of strikes...... specification for the risk-neutral asset return dynamics, the option prices are nonlinear functions of a time-invariant parameter vector and a time-varying latent state vector (or factors). Furthermore, no-arbitrage restrictions impose a direct link between some of the quantities that may be identified from...

  3. POTENTIAL FOR NON-CONTACT ACL INJURY BETWEEN STEP-CLOSE-JUMP AND HOP-JUMP TASKS

    Directory of Open Access Journals (Sweden)

    Li-I Wang

    2010-03-01

    Full Text Available This study aimed to compare the kinematics and kinetics during the landing of hop-jump and step-close-jump movements in order to provide further inferring that the potential risk of ACL injuries. Eleven elite male volleyball players were recruited to perform hop-jump and step-close-jump tasks. Lower extremity kinematics and ground reaction forces during landing in stop-jump tasks were recorded. Lower extremity kinetics was calculated by using an inverse dynamic process. Step-close-jump tasks demonstrated smaller peak proximal tibia anterior shear forces during the landing phase. In step-close-jump tasks, increasing hip joint angular velocity during initial foot-ground contact decreased peak posterior ground reaction force during the landing phase, which theoretically could reduce the risk of ACL injury

  4. Price jumps on European stock markets

    Czech Academy of Sciences Publication Activity Database

    Hanousek, Jan; Kočenda, Evžen; Novotný, Jan

    2014-01-01

    Roč. 14, č. 1 (2014), s. 10-22 ISSN 2214-8450 R&D Projects: GA ČR(CZ) GAP403/11/0020; GA ČR(CZ) GBP402/12/G097 Grant - others:UK(CZ) UNCE 204005/2012 Institutional support: PRVOUK-P23 Keywords : stock markets * price jump indicators * non-parametric testing Subject RIV: AH - Economics

  5. Jump-diffusion processes in random environments

    Science.gov (United States)

    Jakubowski, Jacek; Niewęgłowski, Mariusz

    2014-10-01

    In this paper we investigate jump-diffusion processes in random environments which are given as the weak solutions of SDEs. We formulate conditions ensuring existence and uniqueness in law of solutions. We investigate the Markov property. To prove uniqueness we solve a general martingale problem for càdlàg processes. This result is of independent interest. Application of our results to generalized exponential Lévy model are present in the last section.

  6. Take-off aerodynamics in ski jumping.

    Science.gov (United States)

    Virmavirta, M; Kivekäs, J; Komi, P V

    2001-04-01

    The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, resulting in a higher vertical velocity (V(v)) than is expected from the conventional calculation of V(v) from the force impulse. The wind conditions emphasized the explosiveness of the ski jumping take-off. The aerodynamic lift and drag forces which characterize the aerodynamic quality of the initial take-off position (static in-run position) varied widely even between the examined elite ski jumpers. According to the computer simulation these differences can decisively affect jumping distance. The proper utilization of the prevailing aerodynamic forces before and during take-off is a very important prerequisite for achieving a good flight position.

  7. Biphasic activity of a jumping spider

    Science.gov (United States)

    Okuyama, Toshinori

    2011-01-01

    Individual variation is a ubiquitous and important factor that affects ecological dynamics. This study examined individual variation in the nest-use pattern of the jumping spider Phidippus audax. Although the jumping spider is a diurnal species, field observations in this study revealed that the majority of individuals remained in their nests during the day. An accompanying examination of the hunger level of the spiders revealed that spiders that remained in nests were more starved than those observed outside nests. If spiders actively forage when they are starved, as has been suggested by previous studies, one would expect to see the opposite trend (i.e., spiders that remained in nests are more satiated). Thus, the pattern observed in the field contradicts the known behavioral pattern of the spiders. An individual-based model was used to investigate the behavioral mechanism of the spider and the discrepancy found in the observations. A basic assumption of the model is that spiders possess distinct inactive and active phases (biphasic activity pattern), and transitions between the two phases are regulated by the hunger level of the spider. Data from a laboratory experiment were used to examine the assumptions of the model partially. The model was able to capture patterns observed in the data, suggesting that the pattern of transitions in biphasic activity is an important trait of the foraging behavior of the jumping spider.

  8. An efficient interpolation technique for jump proposals in reversible-jump Markov chain Monte Carlo calculations

    Science.gov (United States)

    Farr, W. M.; Mandel, I.; Stevens, D.

    2015-06-01

    Selection among alternative theoretical models given an observed dataset is an important challenge in many areas of physics and astronomy. Reversible-jump Markov chain Monte Carlo (RJMCMC) is an extremely powerful technique for performing Bayesian model selection, but it suffers from a fundamental difficulty and it requires jumps between model parameter spaces, but cannot efficiently explore both parameter spaces at once. Thus, a naive jump between parameter spaces is unlikely to be accepted in the Markov chain Monte Carlo (MCMC) algorithm and convergence is correspondingly slow. Here, we demonstrate an interpolation technique that uses samples from single-model MCMCs to propose intermodel jumps from an approximation to the single-model posterior of the target parameter space. The interpolation technique, based on a kD-tree data structure, is adaptive and efficient in modest dimensionality. We show that our technique leads to improved convergence over naive jumps in an RJMCMC, and compare it to other proposals in the literature to improve the convergence of RJMCMCs. We also demonstrate the use of the same interpolation technique as a way to construct efficient "global" proposal distributions for single-model MCMCs without prior knowledge of the structure of the posterior distribution, and discuss improvements that permit the method to be used in higher dimensional spaces efficiently.

  9. Jumping performance of flea hoppers and other mirid bugs (Hemiptera, Miridae).

    Science.gov (United States)

    Burrows, M; Dorosenko, M

    2017-05-01

    The order Hemiptera includes jumping insects with the fastest take-off velocities, all generated by catapult mechanisms. It also contains the large family Miridae or plant bugs. Here, we analysed the jumping strategies and mechanisms of six mirid species from high-speed videos and from the anatomy of their propulsive legs, and conclude that they use a different mechanism in which jumps are powered by the direct contractions of muscles. Three strategies were identified. First, jumping was propelled only by movements of the middle and hind legs, which were, respectively, 140% and 190% longer than the front legs. In three species with masses ranging from 3.4 to 12.2 mg, depression of the coxo-trochanteral and extension of femoro-tibial joints accelerated the body in 8-17 ms to take-off velocities of 0.5-0.8 m s -1 The middle legs lost ground contact 5-6 ms before take-off so that the hind legs generated the final propulsion. The power requirements could be met by the direct muscle contractions so that catapult mechanisms were not implicated. Second, other species combined the same leg movements with wing beating to generate take-off during a wing downstroke. Third, up to four wingbeat cycles preceded take-off and were not assisted by leg movements. Take-off velocities were reduced and acceleration times lengthened. Other species from the same habitat did not jump. The lower take-off velocities achieved by powering jumping by direct muscle contractions may be offset by eliminating the time taken to load catapult mechanisms. © 2017. Published by The Company of Biologists Ltd.

  10. Jumping robots: a biomimetic solution to locomotion across rough terrain.

    Science.gov (United States)

    Armour, Rhodri; Paskins, Keith; Bowyer, Adrian; Vincent, Julian; Megill, William; Bomphrey, Richard

    2007-09-01

    This paper introduces jumping robots as a means to traverse rough terrain; such terrain can pose problems for traditional wheeled, tracked and legged designs. The diversity of jumping mechanisms found in nature is explored to support the theory that jumping is a desirable ability for a robot locomotion system to incorporate, and then the size-related constraints are determined from first principles. A series of existing jumping robots are presented and their performance summarized. The authors present two new biologically inspired jumping robots, Jollbot and Glumper, both of which incorporate additional locomotion techniques of rolling and gliding respectively. Jollbot consists of metal hoop springs forming a 300 mm diameter sphere, and when jumping it raises its centre of gravity by 0.22 m and clears a height of 0.18 m. Glumper is of octahedral shape, with four 'legs' that each comprise two 500 mm lengths of CFRP tube articulating around torsion spring 'knees'. It is able to raise its centre of gravity by 1.60 m and clears a height of 1.17 m. The jumping performance of the jumping robot designs presented is discussed and compared against some specialized jumping animals. Specific power output is thought to be the performance-limiting factor for a jumping robot, which requires the maximization of the amount of energy that can be stored together with a minimization of mass. It is demonstrated that this can be achieved through optimization and careful materials selection.

  11. Structural and high-frequency resistive characteristics of MgB2 in the range 0-110 MHz at 5-300 K

    International Nuclear Information System (INIS)

    Dmitriev, V.M.; Prentslau, N.N.; Baumer, V.N.; Galtsov, N.N.; Ishchenko, L.A.; Prokhvatilov, A.I.; Strzhemechnyj, M.A.; Terekhov, A.V.; Bykov, A.I.; Lyashenko, V.I.; Paderno, Yu.B.; Paderno, V.N.

    2004-01-01

    The structure and electrical resistivity of polycrystalline MgB 2 are investigated in the interval 5-300 K. Its impedance is investigated in the same temperature range in the frequency region 9-110 MHz. It is shown that the lattice type and the superconducting-phase symmetry of MgB 2 are invariant in the whole temperature interval. In the region of superconducting transition temperature T c = 39.5 K, a structural instability is observed, which is accompanied by a scatter in the lattice parameters measured. It is suggested that the crystal deformation with varying temperature is significantly anisotropic. The measurements of the temperature and frequency dependences of the surface resistance R s (T, f) in the superconducting state have revealed a transition from the Pippard nonlocal limit at T c to a London local one near Tc. At T/Tc s (T) is well described by the exponential dependence exp (- Δ (T) / k T) in accordance with the BCS theory

  12. Study of atomic jumps in quasi-crystals; Etude des sauts atomiques dans les quasi-cristaux

    Energy Technology Data Exchange (ETDEWEB)

    Lyonnard, S

    1997-05-07

    The terminology phason used in quasicrystals to refer to atomic jumps. The study of the hopping process is important for the understanding of many basic issues in quasi-crystallography: structure, stability, diffusion, phase transitions between quasicrystals and approximants, mechanical properties. Quasi-elastic neutron scattering allows to find the characteristics of each elementary jump: chemical species involves, relaxation times, activation energies, jump distances and orientations. We performed a series of experiments in the perfect icosahedral phases AlFeCu and AlMnPd, on both powders and single domain samples, using time-of-flight, backscattering and triple axis spectrometers. We evidenced the existence of very fast phason hopping, and studied about ten different atomic jumps. An unusual temperature dependence has been found systematically: each process is assisted by a thermally activated mechanism. The assistance process has to be determined case by case, but the more plausible explanation invokes assistance by phonons or phason clouds. Moreover, the dependence of the quasi elastic signal as a function of the momentum transfer shows that the jumps are local and do not give rise to any long-range diffusion. Phason hopping mainly corresponds to the atom moving forwards and backwards between two energetically equivalent sites. Finally, we have been able to show that the jumps occur along the various quasi-crystalline symmetry axes. (author) 91 refs.

  13. An experimental study of turbulent two-phase flow in hydraulic jumps and application of a triple decomposition technique

    Science.gov (United States)

    Wang, Hang; Felder, Stefan; Chanson, Hubert

    2014-07-01

    Intense turbulence develops in the two-phase flow region of hydraulic jump, with a broad range of turbulent length and time scales. Detailed air-water flow measurements using intrusive phase-detection probes enabled turbulence characterisation of the bubbly flow, although the phenomenon is not a truly random process because of the existence of low-frequency, pseudo-periodic fluctuating motion in the jump roller. This paper presents new measurements of turbulent properties in hydraulic jumps, including turbulence intensity, longitudinal and transverse integral length and time scales. The results characterised very high turbulent levels and reflected a combination of both fast and slow turbulent components. The respective contributions of the fast and slow motions were quantified using a triple decomposition technique. The decomposition of air-water detection signal revealed "true" turbulent characteristics linked with the fast, microscopic velocity turbulence of hydraulic jumps. The high-frequency turbulence intensities were between 0.5 and 1.5 close to the jump toe, and maximum integral turbulent length scales were found next to the bottom. Both decreased in the flow direction with longitudinal turbulence dissipation. The results highlighted the considerable influence of hydrodynamic instabilities of the flow on the turbulence characterisation. The successful application of triple decomposition technique provided the means for the true turbulence properties of hydraulic jumps.

  14. Ski jumping boots limit effective take-off in ski jumping.

    Science.gov (United States)

    Virmavirta, M; Komi, P V

    2001-12-01

    In this study, we measured the vertical and horizontal take-off forces, plantar pressures and activation patterns of four muscles (vastus lateralis, gluteus maximus, tibialis anterior, gastrocnemius) in 10 ski jumpers in simulated laboratory conditions when wearing either training shoes or ski jumping boots. We found significant differences in vertical (P boots condition resulted in a smaller displacement in the final position of the following joint angles: ankle angle (P knee angle (P boots condition, significantly more pressure was recorded under the heel (P knee and hip extensors when wearing jumping boots. We conclude that the stiffness of the structure of the jumping boots may result in a forward shift of pressure, thus limiting the effective vertical force. To avoid this pressure shift, the pattern of movement of simulated take-offs should be carefully controlled, particularly when wearing training shoes.

  15. Thermal shock and thermal fatigue resistant ZrO2/Al2O3 ceramics in the eutectic composition range. Pt. 1

    International Nuclear Information System (INIS)

    Liu, T.; Dorfschmidt, K.; Oberacker, R.

    1992-01-01

    Thermal shock and thermal fatigue resistant ZrO 2 /Al 2 O 3 ceramics in the eutectic composition range have been prepared and characterized in this work. The microstructures such as chemical composition (Al 2 O 3 -content), stabilizer (Y 2 O 3 , CeO 2 ), porosity, grain size and crack configuration (duplex, dendrite microstructure) have been varied systematically by different processing techniques. Mechanical properties such as Youngs modulus, bending strength, fracture toughness and R-curve behaviour have been investigated. Interrelations between the above microstructures and the mechanical properties have been established. Optimized combination of high toughness and high strength has been reached in crack free, fine-grained Ce-stabilized ZA-materials. On the other hand pronounced inelastic behaviour has been measured by optimization of the crack configuration in the duplex and dendrite microstructures. 6 refs., 1 tab., 10 figs

  16. Assessment of In Vivo Efficacy of Eravacycline against Enterobacteriaceae Exhibiting Various Resistance Mechanisms: A Dose-Ranging Study and PK/PD Analysis.

    Science.gov (United States)

    Thabit, Abrar K; Monogue, Marguerite L; Newman, Joseph V; Nicolau, David P

    2018-01-08

    After the pharmacokinetic (PK) profile of eravacycline as a novel fluorocycline was defined, understanding its pharmacodynamic (PD) profile became essential. The aim of this study was to assess the correlation of the PK/PD index of the area under free drug concentration-time curve above the minimum inhibitory concentration (fAUC/MIC) and its magnitude with eravacycline's efficacy against Enterobacteriaceae isolates using the immunocompetent murine thigh infection model to resemble the immunocompetent environment in eravacycline's clinical trials. Eight Enterobacteriaceae isolates with various resistance mechanisms were selected and tested. Eravacycline doses ranged 1-10 mg/kg/day and were given either once daily or divided into q12h doses over the 24h treatment period. Antibacterial efficacy was measured as the change in log 10 CFU at 24h compared with 0h controls. Composite data were modeled using a sigmoid E max model. Eravacycline MICs ranged 0.125-0.5 µg/ml. The mean fAUC/MIC magnitudes required for stasis and 1-log reduction for the eight isolates were 2.9 ± 3.1 and 5.6 ± 5.0, respectively. While the humanized eravacycline regimen (2.5 mg/kg q12h) pharmacokinetically achieves a fAUC 0-24 that is higher than the fAUC 0-24 achieved with the 5 mg/kg q24h dose, the latter was associated with higher efficacy raising a suggestive correlation of the free peak drug concentration to the MIC (fC max /MIC) index with eravacycline's efficacy. This study showed that the magnitudes associated with the efficacy of eravacycline in the immunocompetent murine thigh model appear to be close to achievable targets in human. These data support further development of eravacycline for the treatment of infections caused by drug-resistant Enterobacteriaceae. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  17. A Jump-Diffusion Model with Stochastic Volatility and Durations

    DEFF Research Database (Denmark)

    Wei, Wei; Pelletier, Denis

    Market microstructure theories suggest that the durations between transactions carry information about volatility. This paper puts forward a model featuring stochastic volatility, stochastic conditional duration, and jumps to analyze high frequency returns and durations. Durations affect price...... jumps in two ways: as exogenous sampling intervals, and through the interaction with volatility. We adopt a bivariate Ornstein-Ulenbeck process to model intraday volatility and conditional duration. We develop a MCMC algorithm for the inference on irregularly spaced multivariate processes with jumps...

  18. Suicides by Jumping Off Istanbul Bridges Linking Asia and Europe.

    Science.gov (United States)

    Yurtseven, Ayşe; Üzün, İbrahim; Arslan, Murat Nihat

    2017-06-01

    The aim of this study was to determine the injury spectrum and characteristics of people who committed suicide by jumping into water from the July 15th Martyrs Bridge and Fatih Sultan Mehmet Bridges in Istanbul, Turkey. This study included all of the jumpers from the July 15th Martyrs Bridge and Fatih Sultan Mehmet Bridge who were autopsied by the Council of Forensic Medicine, Istanbul Morgue Department, between 2000 and 2013. All of the data were collected from archived case files. Trauma scores were calculated from the traumatic findings of the autopsy reports using the New Injury Severity Score (NISS). A total of 80 jumping suicides were identified. The male-to-female ratio was 9:1, and the mean age was 34.06 ± 9.6 years. Most suicides occurred in 2009. The suicide rates were higher in the winter, particularly in December. The most frequent injuries were skin lesions, rib fractures, and lung lacerations. In 12% of the cases, the trauma was minor (NISS range, 0-14; mean, 7 ± 5.67), and in 88% of the cases, it was major (NISS range, 17-66; mean NISS, 44.5 ± 12.46). The sociodemographic features of the jumpers who committed suicide were quite similar to those reported in previous studies. Preventative measures (installation of barriers or banning pedestrian access to bridges) reduced the suicide rate but were not completely effective. Establishing early warning systems and rescue strategies could save the lives of jumpers who have minor trauma.

  19. Development of a Minimally Actuated Jumping-Rolling Robot

    Directory of Open Access Journals (Sweden)

    Thanhtam Ho

    2015-04-01

    Full Text Available This paper presents development of a hybrid mobile robot in order to take advantage of both rolling and jumping locomotion on the ground. According to the unique design of the mechanism, the robot is able to execute both jumping and rolling skilfully by using only one DC motor. Changing the centre of gravity enables rolling of the robot and storage of energy is utilized for jumping. Mechanism design and control logic are validated by computer simulation. Simulation results show that the robot can jump nearly 1.3 times its diameter and roll at the speed of 3.3 times its diameter per second.

  20. Biomechanics research in ski jumping, 1991-2006.

    Science.gov (United States)

    Schwameder, Hermann

    2008-01-01

    In this paper, I review biomechanics research in ski jumping with a specific focus on publications presented between 1991 and 2006 on performance enhancement, limiting factors of the take-off, specific training and conditioning, aerodynamics, and safety. The first section presents a brief description of ski jumping phases (in-run, take-off, early flight, stable flight, and landing) regarding the biomechanical and functional fundamentals. The most important and frequently used biomechanical methods in ski jumping (kinematics, ground reaction force analyses, muscle activation patterns, aerodynamics) are summarized in the second section. The third section focuses on ski jumping articles and research findings published after the establishment of the V-technique in 1991, as the introduction of this technique has had a major influence on performance enhancement, ski jumping regulations, and the construction of hill profiles. The final section proposes topics for future research in the biomechanics of ski jumping, including: take-off and early flight and the relative roles of vertical velocity and forward somersaulting angular momentum; optimal jumping patterns utilizing the capabilities of individual athletes; development of kinematic and kinetic feedback systems for hill jumps; comparisons of simulated and hill jumps; effect of equipment modifications on performance and safety enhancement.

  1. Effect of drop jump technique on the reactive strength index

    Directory of Open Access Journals (Sweden)

    Struzik Artur

    2016-09-01

    Full Text Available The basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI for countermovement drop jumps (CDJs and bounce drop jumps (BDJs. The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p < 0.05 between RSI values for CDJs and BDJs were recorded for jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p < 0.05 than the values recorded for BDJs. Times of contact, amortization and take-off during BDJs were significantly shorter (p < 0.05 than the respective values obtained for CDJs. Therefore, the use of the RSI to monitor plyometric training should be based on the drop jump technique that is commonly performed by basketball players.

  2. Effect of drop jump technique on the reactive strength index.

    Science.gov (United States)

    Struzik, Artur; Juras, Grzegorz; Pietraszewski, Bogdan; Rokita, Andrzej

    2016-09-01

    The basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI) for countermovement drop jumps (CDJs) and bounce drop jumps (BDJs). The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p training should be based on the drop jump technique that is commonly performed by basketball players.

  3. Measurement of K-shell absorption jump factors and jump ratios in some lanthanide elements using EDXRF technique

    International Nuclear Information System (INIS)

    Polat, Recep; İçelli, Orhan; Yalçın, Zeynel; Pesen, Erhan; Orak, Salim

    2013-01-01

    Highlights: ► Mass attenuation coefficients, jump factor and jump ratio for lanthanide elements are obtained. ► The method used in this experiment is combined both transmission and scattering geometry. ► Secondary gamma rays energy is 59.5 keV. ► Experimental values of jump factor and jump ratio for K shell are new. ► The experimental values are in good agreement with those calculated theoretically. - Abstract: 59.5 keV gamma rays scattered by an aluminum foil have been used as a radiation source to measure the absorption jump factor and jump ratios for absorbers Ce, Pr, Nd, Sm, Eu and Tb. The theoretical and experimental values are compared with the corresponding ones in the literature

  4. Generator estimation of Markov jump processes based on incomplete observations nonequidistant in time

    Science.gov (United States)

    Metzner, Philipp; Horenko, Illia; Schütte, Christof

    2007-12-01

    Markov jump processes can be used to model the effective dynamics of observables in applications ranging from molecular dynamics to finance. In this paper we present a different method which allows the inverse modeling of Markov jump processes based on incomplete observations in time: We consider the case of a given time series of the discretely observed jump process. We show how to compute efficiently the maximum likelihood estimator of its infinitesimal generator and demonstrate in detail that the method allows us to handle observations nonequidistant in time. The method is based on the work of and Bladt and Sørensen [J. R. Stat. Soc. Ser. B (Stat. Methodol.) 67, 395 (2005)] but scales much more favorably than it with the length of the time series and the dimension and size of the state space of the jump process. We illustrate its performance on a toy problem as well as on data arising from simulations of biochemical kinetics of a genetic toggle switch.

  5. Hierarchical Superhydrophobic Surfaces with Micropatterned Nanowire Arrays for High-Efficiency Jumping Droplet Condensation.

    Science.gov (United States)

    Wen, Rongfu; Xu, Shanshan; Zhao, Dongliang; Lee, Yung-Cheng; Ma, Xuehu; Yang, Ronggui

    2017-12-27

    Self-propelled droplet jumping on nanostructured superhydrophobic surfaces is of interest for a variety of industrial applications including self-cleaning, water harvesting, power generation, and thermal management systems. However, the uncontrolled nucleation-induced Wenzel state of condensed droplets at large surface subcooling (high heat flux) leads to the formation of unwanted large pinned droplets, which results in the flooding phenomenon and greatly degrades the heat transfer performance. In this work, we present a novel strategy to manipulate droplet behaviors during the process from the droplet nucleation to growth and departure through a combination of spatially controlling initial nucleation for mobile droplets by closely spaced nanowires and promoting the spontaneous outward movement of droplets for rapid removal using micropatterned nanowire arrays. Through the optical visualization experiments and heat transfer tests, we demonstrate greatly improved condensation heat transfer characteristics on the hierarchical superhydrophobic surface including the higher density of microdroplets, smaller droplet departure radius, 133% wider range of surface subcooling for droplet jumping, and 37% enhancement in critical heat flux for jumping droplet condensation, compared to the-state-of-art jumping droplet condensation on nanostructured superhydrophobic surfaces. The excellent water repellency of such hierarchical superhydrophobic surfaces can be promising for many potential applications, such as anti-icing, antifogging, water desalination, and phase-change heat transfer.

  6. Effect of take-off from prosthetic versus intact limb on transtibial amputee long jump technique.

    Science.gov (United States)

    Nolan, L; Patritti, Benjamin L; Simpson, Kathy J

    2012-09-01

    Increasing numbers of long jumpers with lower limb amputations choose to take off from their prosthetic limb. It is not yet known what difference in technique, if any, this requires, or which is more advantageous. To investigate kinematic differences in long jump technique in athletes with a unilateral transtibial ampution (TT) who take off from their prosthetic limb versus those who take off from their intact limb. Naturalistic, field-based, observational; independent group, nonparametric comparison. Two-dimensional sagittal plane kinematic analysis was performed on all athletes competing in the men's Paralympic TT long jump finals. Five athletes took off from their prosthetic limb (TO(prosth)) and five from their intact limb (TO(intact)). No differences were seen between the two groups in terms of jump distance, approach speed or vertical velocity at touch down. While in contact with the take-off board, the two groups gained a similar amount of vertical velocity. However, the TO(prosth) group appeared to conserve horizontal velocity by using the prosthesis as a 'springboard', minimizing the large hip and knee range of motion displayed by the TO(intact) group and athletes in previous studies. While differences in technique were observed, no difference was found for jump distance.

  7. Magnetic moment jumps in flat and nanopatterned Nb thin-walled cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Tsindlekht, M.I., E-mail: mtsindl@vms.huji.ac.il [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Genkin, V.M.; Felner, I.; Zeides, F.; Katz, N. [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Gazi, Š.; Chromik, Š. [The Institute of Electrical Engineering SAS, Dúbravská cesta 9, 84104 Bratislava (Slovakia); Dobrovolskiy, O.V. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany); Physics Department, V. Karazin Kharkiv National University, 61077 Kharkiv (Ukraine); Sachser, R.; Huth, M. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany)

    2017-02-15

    Highlights: • Magnetization curves of as-prepared and patterned thin-walled cylinders were measured in magnetic fields applied parallel to cylinders axis. • Magnetic moment jumps were observed in magnetic fields lower and above Hc1. • Critical current density in isthmus between two antidots is higher than in a film itself. - Abstract: Penetration of magnetic flux into hollow superconducting cylinders is investigated by magnetic moment measurements. The magnetization curves of a flat and a nanopatterned thin-walled superconducting Nb cylinders with a rectangular cross section are reported for the axial field geometry. In the nanopatterned sample, a row of micron-sized antidots (holes) was milled in the film along the cylinder axis. Magnetic moment jumps are observed for both samples at low temperatures for magnetic fields not only above H{sub c1}, but also in fields lower than H{sub c1}, i. e., in the vortex-free regime. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than H{sub c1}. At temperatures above 0.66T{sub c} and 0.78T{sub c} the magnetization curves become smooth for the patterned and the as-prepared sample, respectively. The magnetization curve of a reference flat Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures.

  8. Mechanical output about the ankle in countermovement jumps and jumps with extended knee

    NARCIS (Netherlands)

    de Graaf, J. B.; Bobbert, M. F.; Tetteroo, W. E.; van Ingen Schenau, G. J.

    1987-01-01

    In this study the mechanical output (e.g., force, contraction velocity, instantaneous power) about the ankle was measured during a jump with and without occurrence of transportation of power and pre-stretch potentiation. To examine this, a model of the m. triceps surae was used. Eleven subjects

  9. High-intensity, unilateral resistance training of a non-paretic muscle group increases active range of motion in a severely paretic upper extremity muscle group after stroke.

    Directory of Open Access Journals (Sweden)

    M. A. Urbin

    2015-05-01

    Full Text Available Limited rehabilitation strategies are available for movement restoration when paresis is too severe following stroke. Previous research has shown that high-intensity resistance training of one muscle group enhances strength of the homologous, contralateral muscle group in neurologically-intact adults. How this cross education phenomenon might be exploited to moderate severe weakness in an upper extremity muscle group after stroke is not well understood. The primary aim of this study was to examine adaptations in force-generating capacity of severely paretic wrist extensors resulting from high-intensity, dynamic contractions of the non-paretic wrist extensors. A secondary, exploratory aim was to probe neural adaptations in a subset of participants from each sample using a single-pulse, transcranial magnetic stimulation protocol. Separate samples of neurologically-intact controls (n=7 and individuals > 4 months post stroke (n=6 underwent 16 sessions of training. Following training, one-repetition maximum of the untrained wrist extensors in the control group and active range of motion of the untrained, paretic wrist extensors in the stroke group were significantly increased. No changes in corticospinal excitability, intracortical inhibition or interhemispheric inhibition were observed in control participants. Both stroke participants who underwent TMS testing, however, exhibited increased voluntary muscle activation following the intervention. In addition, motor-evoked potentials that were unobtainable prior to the intervention were readily elicited afterwards in a stroke participant. Results of this study demonstrate that high-intensity resistance training of a non-paretic upper extremity muscle group can enhance voluntary muscle activation and force-generating capacity of a severely paretic muscle group after stroke. There is also preliminary evidence that corticospinal adaptations may accompany these gains.

  10. Treinamento de força com uso de correntes e potencialização pós-ativação do salto vertical Entrenamiento de fuerza con cadenas y la potenciación post-activación del salto vertical Chain resistance training and vertical jump post-activation potentiation

    Directory of Open Access Journals (Sweden)

    Jéderson Nunes

    2012-12-01

    Full Text Available A Potencialização Pós-Ativação (PPA é estratégia para melhora do desempenho com uso de carga fixa (RF, definida no ponto de falha mecânica (PFM. Por outro lado, o uso de correntes (CRT é estímulo com resistência variável (RV. Assim, objetivou-se avaliar os efeitos do CRT na altura e tempo de voo do salto vertical com contramovimento (CMJ. A partir de estudo de intervenção, 15 sujeitos foram avaliados quanto à carga máxima no agachamento (1RM e altura CMJ. Após isto, executaram três tipos de intervenções: i RF com 85% de 1RM; ii RV com 85% de 1RM posicionado no PFM (RV-TF e, iii RV com 85% de 1RM posicionado na maior extensão dos joelhos (RV-TV. Observou-se incremento do CMJ para RV-TF e RV-TV, mas não para RF. Conclui-se que houve PPA com os dois estímulos de CRT.La potenciación post-activación (PAP es estrategia para mejorar el rendimiento, utilizando una carga fija (RF, que se define en el punto de falla mecánica (PFM. Además, el uso de cadenas (CRT es estimulo con resistencia variable (RV. Así, el objetivo fue evaluar los efectos de la CRT en el salto vertical con contramovimiento (CMJ. Con estudio de intervención, 15 sujetos fueron evaluados acerca de la carga máxima en la sentadilla (1RM y altura en el CMJ. Después de eso, se realizaron tres tipos de intervenciones: i RF con el 85% de 1RM; ii RV con el 85% de 1RM en el PFM (RV-TF, y iii la RV en 1RM 85% situado en la mayor extensión de las rodillas (RV-TV. Se observó aumento de lo CMJ para RV-TF y RV-TV, pero no para la RF. Se concluye que existe PPA con los dos estímulos de RV.The Post-Activation Potentiation (PAP is a strategy to improve performance, using a fixed load (RF, defined at the sticking point (PFM. Moreover, the use of chains (CRT is an effort with variable resistance (RV. Thus, the objective was to evaluate the effects of CRT in the countermovement jump (CMJ. With an intervention study, 15 subjects were evaluated for the maximum squat load (1

  11. A jumping cylinder in an incline

    Science.gov (United States)

    Gomez, Raul W.; Hernandez, Jorge; Marquina, Vivianne

    2012-02-01

    The problem of a cylinder of mass m and radius r, with its center of mass out of the cylinder axis, rolling in an incline that makes an angle α respect to the horizontal is analyzed. The equation of motion is solved to obtain the site where the cylinder loses contact with the incline (jumps). Several simplifications are made: the analyzed system consists of an homogeneous disc with a one dimensional straight line of mass parallel to the disc axis at a distance d Styrofoam cylinder of radius r = 10.0 ± 0.05 cm, high h = 5.55 ± 0.05 cm and a mass m1 = 24.45 ± 0.05 g, to which a 9.50 ± 0.01 mm diameter and 5.10 ± 0.001 cm long brass road of mass m2 = 30.75 ± 0.05 g was imbibed parallel to the disc axis at a distance of 5.40 ± 0.05 cm from it. Then the disc rolls on a 3.20 m long wooden ramp inclined at 30 and 45 respect to the horizontal. To determine the jumping site, the movements were recorded with a high-speed video camera (Casio EX ZR100) at 400 frames per second. The experimental results agree well with the theoretical predictions.

  12. Understanding the physics of bungee jumping

    Science.gov (United States)

    Heck, André; Uylings, Peter; Kędzierska, Ewa

    2010-01-01

    Changing mass phenomena like the motion of a falling chain, the behaviour of a falling elastic bar or spring, and the motion of a bungee jumper surprise many a physicist. In this article we discuss the first phase of bungee jumping, when the bungee jumper falls, but the bungee rope is still slack. In instructional material this phase is often considered a free fall, but when the mass of the bungee rope is taken into account, the bungee jumper reaches acceleration greater than g. This result is contrary to the usual experience with free falling objects and therefore hard to believe for many a person, even an experienced physicist. It is often a starting point for heated discussions about the quality of the experiments and the physics knowledge of the experimentalist, or it may even prompt complaints about the quality of current physics education. But experiments do reveal the truth and students can do them supported by information and communication technology (ICT) tools. We report on a research project done by secondary school students and use their work to discuss how measurements with sensors, video analysis of self-recorded high-speed video clips and computer modelling allow study of the physics of bungee jumping.

  13. Chasing maximal performance: a cautionary tale from the celebrated jumping frogs of Calaveras County.

    Science.gov (United States)

    Astley, H C; Abbott, E M; Azizi, E; Marsh, R L; Roberts, T J

    2013-11-01

    Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs (Rana catesbeiana). We recorded video of 3124 bullfrog jumps over the course of the 4-day contest at the Calaveras County Jumping Frog Jubilee, and determined jump distance from these images and a calibration of the jump arena. Frogs were divided into two groups: 'rental' frogs collected by fair organizers and jumped by the general public, and frogs collected and jumped by experienced, 'professional' teams. A total of 58% of recorded jumps surpassed the maximum jump distance in the literature (1.295 m), and the longest jump was 2.2 m. Compared with rental frogs, professionally jumped frogs jumped farther, and the distribution of jump distances for this group was skewed towards long jumps. Calculated muscular work, historical records and the skewed distribution of jump distances all suggest that the longest jumps represent the true performance limit for this species. Using resampling, we estimated the probability of observing a given jump distance for various sample sizes, showing that large sample sizes are required to detect rare maximal jumps. These results show the importance of sample size, animal motivation and physiological conditions for accurate maximal performance estimates.

  14. Reliability of the Tuck Jump Injury Risk Screening Assessment in Elite Male Youth Soccer Players.

    Science.gov (United States)

    Read, Paul J; Oliver, Jon L; de Ste Croix, Mark B A; Myer, Gregory D; Lloyd, Rhodri S

    2016-06-01

    Read, PJ, Oliver, JL, de Ste Croix, MBA, Myer, GD, and Lloyd, RS. Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players. J Strength Cond Res 30(6): 1510-1516, 2016-Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high-risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a preparticipation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. Twenty-five pre-peak height velocity (PHV) and 25 post-PHV elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test-retest design was used to explore the within-subject intersession reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90-1.01 in pre-PHV and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test-retest comparison.

  15. Dynamics of force and muscle stimulation in human vertical jumping

    NARCIS (Netherlands)

    Bobbert, M.F.; van Zandwijk, J.P.

    1999-01-01

    PURPOSE: The purpose of this study was to gain insight into the importance of stimulation dynamics for force development in human vertical jumping. METHODS: Maximum height squat jumps were performed by 21 male subjects. As a measure of signal dynamics, rise time (RT) was used, i.e., the time taken

  16. How Can We Tell if Frogs Jump Further?

    Science.gov (United States)

    Drummond, Gordon B.; Tom, Brian D. M.

    2011-01-01

    How effective is training frogs to jump? This is perhaps the most frequent question in biology that is subjected to statistical analysis: does a treatment make a difference? One can examine whether there is indeed a training effect, by first assuming the opposite. That is, the authors assume that training has no effect on the mean distance jumped.…

  17. The world price of jump and volatility risk

    NARCIS (Netherlands)

    Driessen, J.; Maenhout, P.

    2006-01-01

    Jump and volatility risk are important for understanding equity returns, option pricing and asset allocation. This paper is the first to study international integration of markets for jump and volatility risk, using data on index options for each of the three main global markets: US S&P 500 index

  18. Basketball jump shooting is controlled online by vision.

    NARCIS (Netherlands)

    Ferraz De Oliveira, R.M.; Huys, R.; Oudejans, R.R.D.; van der Langenberg, R.W.; Beek, P.J.

    2007-01-01

    An experiment was conducted to examine whether basketball jump shooting relies on online visual (i.e., dorsal stream-mediated) control rather than motor preprogramming. Seventeen expert basketball players (eight males and nine females) performed jump shots under normal vision and in three conditions

  19. JUMPING AND LANDING TECHNIQUES IN ELITE WOMEN'S VOLLEYBALL

    Directory of Open Access Journals (Sweden)

    Denis Brunt

    2004-03-01

    Full Text Available Volleyball has become one of the most widely played participant sports in the world. Participation requires expertise in many physical skills and performance is often dependent on an individual's ability to jump and land. The incidence of injury in volleyball is similar to the rates reported for sports that are considered more physical contact sports. Though the most common source of injury in volleyball is the jump landing sequence, little research exists regarding the prevalence of jumping and landing techniques. The purpose of this study was to quantify the number of jumps performed by female volleyball players in competitive matches and to determine the relative frequency of different jump-landing techniques. Videotape recordings of two matches among four volleyball teams were analyzed for this study. Each activity was categorized by jump type (offensive spike or defensive block and phase (jump or landing. Phase was subcategorized by foot use patterns (right, left, or both. Each of the players averaged nearly 22 jump-landings per game. Foot use patterns occurred in unequal amounts (p < 0.001 with over 50% of defensive landings occurring on one foot. Coaches, physical educators, and recreation providers may utilize the findings of this inquiry to help prevent injuries in volleyball

  20. Effects of two different terrains on vertical jump performance | Davies ...

    African Journals Online (AJOL)

    There was however, no significant difference (p>0.05) between the decent distances of the centre of mass during the preparatory phase (squat) of the jump on sand (26.77 cm) compared to the same action on a hard surface (27.09 cm). As a consequence of these findings one may speculate that for any given jumping action ...

  1. Role of the hamstrings in human vertical jumping

    NARCIS (Netherlands)

    Bobbert, Maarten F.

    1996-01-01

    In some human subjects performing maximum-height squat jumps, the EMG-pattern of semitendinosus is bi-phasic and that of biceps femoris is mono-phasic. The purpose of this study was to investigate the roles of biceps femoris and semitendinosus in squat jumping, and to explain why they are different.

  2. Teaching Jump Rope to Children with Visual Impairments

    Science.gov (United States)

    Lieberman, Lauren J.; Schedlin, Haley; Pierce, Tristan

    2009-01-01

    This article presents strategies for jumping rope for children with visual impairments. Giving choices related to the types of rope and the use of mats is important. In addition, using appropriate instructional strategies and modifications will make jumping rope a skill that the children will enjoy and will lead to their involvement in other…

  3. Could the deep squat jump predict weightlifting performance?

    Science.gov (United States)

    Vizcaya, Francisco J; Viana, Oscar; del Olmo, Miguel Fernandez; Acero, Rafael Martin

    2009-05-01

    This research was carried out with the aim of describing the deep squat jump (DSJ) and comparing it with the squat (SJ) and countermovement (CMJ) jumps, to introduce it as a strength testing tool in the monitoring and control of training in strength and power sports. Forty-eight male subjects (21 weightlifters, 12 triathletes, and 15 physical education students) performed 3 trials of DSJ, SJ, and CMJ with a 1-minute rest among them. For the weightlifters, snatch and clean and jerk results during the Spanish Championship 2004 and the 35th EU Championships 2007 were collected to study the relationship among vertical jumps and weightlifters' performance. A 1-way analysis of variance (ANOVA) showed significant differences between groups in the vertical jumps, with the highest jumps for the weightlifters and the lowest for the triathletes. An ANOVA for repeated measures (type of jump) showed better results for DSJ and CMJ than SJ in all groups. A linear regression analysis was performed to determine the association between weightlifting and vertical jump performances. Correlations among the weightlifting performance and the vertical jumps were also calculated and determined using Pearson r. Results have shown that both CMJ and DSJ are strongly correlated with weightlifting ability. Therefore, both measures can be useful for coaches as a strength testing tool in the monitoring and control of training in weightlifting.

  4. Control strategy of maximum vertical jumps: The preferred countermovement depth may not be fully optimized for jump height

    Directory of Open Access Journals (Sweden)

    Mandic Radivoj

    2016-09-01

    Full Text Available The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles.

  5. Control strategy of maximum vertical jumps: The preferred countermovement depth may not be fully optimized for jump height.

    Science.gov (United States)

    Mandic, Radivoj; Knezevic, Olivera M; Mirkov, Dragan M; Jaric, Slobodan

    2016-09-01

    The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles.

  6. Control strategy of maximum vertical jumps: The preferred countermovement depth may not be fully optimized for jump height

    Science.gov (United States)

    Mandic, Radivoj; Knezevic, Olivera M.; Mirkov, Dragan M.

    2016-01-01

    Abstract The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles. PMID:28149396

  7. Nonstandard jump functions for radically symmetric shock waves

    International Nuclear Information System (INIS)

    Baty, Roy S.; Tucker, Don H.; Stanescu, Dan

    2008-01-01

    Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function.

  8. Option Valuation with Observable Volatility and Jump Dynamics

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

    2015-01-01

    Under very general conditions, the total quadratic variation of a jump-diffusion process can be decomposed into diffusive volatility and squared jump variation. We use this result to develop a new option valuation model in which the underlying asset price exhibits volatility and jump intensity...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...... for straightforward filtering and estimation of the model. Our model belongs to the affine class enabling us to derive the conditional characteristic function so that option values can be computed rapidly without simulation. When estimated on S&P500 index options and returns the new model performs well compared...

  9. Option Valuation with Observable Volatility and Jump Dynamics

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

    Under very general conditions, the total quadratic variation of a jump-diffusion process can be decomposed into diffusive volatility and squared jump variation. We use this result to develop a new option valuation model in which the underlying asset price exhibits volatility and jump intensity...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...... for straightforward filtering and estimation of the model. Our model belongs to the affine class enabling us to derive the conditional characteristic function so that option values can be computed rapidly without simulation. When estimated on S&P500 index options and returns the new model performs well compared...

  10. Jump Tails, Extreme Dependencies, and the Distribution of Stock Returns

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Viktor

    We provide a new framework for estimating the systematic and idiosyncratic jump tail risks in financial asset prices. The theory underlying our estimates are based on in-fill asymptotic arguments for directly identifying the systematic and idiosyncratic jumps, together with conventional long......-span asymptotics and Extreme Value Theory (EVT) approximations for consistently estimating the tail decay parameters and asymptotic tail dependencies. On implementing the new estimation procedures with a panel of highfrequency intraday prices for a large cross-section of individual stocks and the aggregate S&P 500...... market portfolio, we find that the distributions of the systematic and idiosyncratic jumps are both generally heavy-tailed and not necessarily symmetric. Our estimates also point to the existence of strong dependencies between the market-wide jumps and the corresponding systematic jump tails for all...

  11. Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant

    OpenAIRE

    Jensen, Kyle C.; Hair, Bryan B.; Wienclaw, Trevor M.; Murdock, Mark H.; Hatch, Jacob B.; Trent, Aaron T.; White, Tyler D.; Haskell, Kyler J.; Berges, Bradford K.

    2015-01-01

    Staphylococcus aureus (SA) is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA) isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA ...

  12. Jump Distance Increases while Carrying Handheld Weights: Impulse, History, and Jump Performance in a Simple Lab Exercise

    Science.gov (United States)

    Butcher, Michael T.; Bertram, John E. A.

    2004-01-01

    This laboratory exercise is designed to provide an understanding of the mechanical concept of impulse as it applies to human movement and athletic performance. Students compare jumps performed with and without handheld weights. Contrary to initial expectation, jump distance is increased with moderate additional weights. This was familiar to…

  13. Barbell deadlift training increases the rate of torque development and vertical jump performance in novices.

    Science.gov (United States)

    Thompson, Brennan J; Stock, Matt S; Shields, JoCarol E; Luera, Micheal J; Munayer, Ibrahim K; Mota, Jacob A; Carrillo, Elias C; Olinghouse, Kendra D

    2015-01-01

    The primary purpose of this study was to examine the effects of 10 weeks of barbell deadlift training on rapid torque characteristics of the knee extensors and flexors. A secondary aim was to analyze the relationships between training-induced changes in rapid torque and vertical jump performance. Fifty-four subjects (age, mean ± SD = 23 ± 3 years) were randomly assigned to a control (n = 20) or training group (n = 34). Subjects in the training group performed supervised deadlift training twice per week for 10 weeks. All subjects performed isometric strength testing of the knee extensors and flexors and vertical jumps before and after the intervention. Torque-time curves were used to calculate rate of torque development (RTD) values at peak and at 50 and 200 milliseconds from torque onset. Barbell deadlift training induced significant pre- to post-increases of 18.8-49.0% for all rapid torque variables (p barbell deadlift training program was effective at enhancing rapid torque capacities in both the knee extensors and flexors. Changes in rapid torque were associated with improvements in vertical jump height, suggesting a transfer of adaptations from deadlift training to an explosive, performance-based task. Professionals may use these findings when attempting to design effective, time-efficient resistance training programs to improve explosive strength capacities in novices.

  14. Effects of Short-Term Jump Squat Training With and Without Chains on Strength and Power in Recreational Lifters

    Directory of Open Access Journals (Sweden)

    David C. Archer

    2016-10-01

    Full Text Available Background: The use of chains in resistance training is a way to accommodate the muscular strength curve. Short-term training and jump squats have been shown to increase back squat strength, but not in conjunction with each other or with chains. Jump squats have also been used to increase jump height and power. Objectives: The purpose of this study was to investigate the effects of short-term jump squat training with and without chains on strength and power. Methods: Thirty-one resistance-trained men volunteered to participate (age = 23.87 ± 2.2 years, height=174.87 ± 6.94 cm, mass = 82.74 ± 14.95 kg and were randomly assigned to one of three groups [control (C = 10, no chains (NC =10, or chains (CH = 11]. Participants had their jump height (VJ and back squat strength (BS tested before and after a week of training. The NC and CH groups performed three training sessions consisting of five sets of three reps of jump squats at 30% 1RM with 30s rest between sets. The CH group had 20% of their load added by chains when standing erect. The C group did not train. Results: A 3 (group: CH, NC, C x 2 (time: pre, post mixed factor ANOVA revealed a significant (p = 0.006 interaction for back squat 1RM. Both the CH (pre 142.56 ± 20.40 kg; post 145.66 ± 19.59 kg and NC (pre 150.00 ± 15.23 kg; post 154.77 ± 15.09 kg groups significantly increased while the C (pre 157.27 ± 25.35 kg; post 156.36 ± 24.85 kg group showed no difference. There were no significant interactions (p =0.32 or main effects for VJ (C = pre 50.59 ± 9.39cm; post 51.29 ± 9.68cm; NC = pre 55.29 ± 5.23cm; post 57.39 ± 5.22cm; CH = pre 46.19 ± 5.02; post 47.45 ± 4.62. Conclusions: The CH group was able to increase strength while lifting less overall weight. Coaches may use short-term training with chains to yield a similar increase in back squat strength as without chains. Keywords: variable resistance, back squats, novel, vertical jump

  15. Seismic tomography with the reversible jump algorithm

    Science.gov (United States)

    Bodin, Thomas; Sambridge, Malcolm

    2009-09-01

    The reversible jump algorithm is a statistical method for Bayesian inference with a variable number of unknowns. Here, we apply this method to the seismic tomography problem. The approach lets us consider the issue of model parametrization (i.e. the way of discretizing the velocity field) as part of the inversion process. The model is parametrized using Voronoi cells with mobile geometry and number. The size, position and shape of the cells defining the velocity model are directly determined by the data. The inverse problem is tackled within a Bayesian framework and explicit regularization of model parameters is not required. The mobile position and number of cells means that global damping procedures, controlled by an optimal regularization parameter, are avoided. Many velocity models with variable numbers of cells are generated via a transdimensional Markov chain and information is extracted from the ensemble as a whole. As an aid to interpretation we visualize the expected earth model that is obtained via Monte Carlo integration in a straightforward manner. The procedure is particularly adept at imaging rapid changes or discontinuities in wave speed. While each velocity model in the final ensemble consists of many discontinuities at cell boundaries, these are smoothed out in the averaged ensemble solution while those required by the data are reinforced. The ensemble of models can also be used to produce uncertainty estimates and experiments with synthetic data suggest that they represent actual uncertainty surprisingly well. We use the fast marching method in order to iteratively update the ray geometry and account for the non-linearity of the problem. The method is tested here with synthetic data in a 2-D application and compared with a subspace method that is a more standard matrix-based inversion scheme. Preliminary results illustrate the advantages of the reversible jump algorithm. A real data example is also shown where a tomographic image of Rayleigh wave

  16. Automated Storm Tracking and the Lightning Jump Algorithm Using GOES-R Geostationary Lightning Mapper (GLM) Proxy Data.

    Science.gov (United States)

    Schultz, Elise V; Schultz, Christopher J; Carey, Lawrence D; Cecil, Daniel J; Bateman, Monte

    2016-01-01

    This study develops a fully automated lightning jump system encompassing objective storm tracking, Geostationary Lightning Mapper proxy data, and the lightning jump algorithm (LJA), which are important elements in the transition of the LJA concept from a research to an operational based algorithm. Storm cluster tracking is based on a product created from the combination of a radar parameter (vertically integrated liquid, VIL), and lightning information (flash rate density). Evaluations showed that the spatial scale of tracked features or storm clusters had a large impact on the lightning jump system performance, where increasing spatial scale size resulted in decreased dynamic range of the system's performance. This framework will also serve as a means to refine the LJA itself to enhance its operational applicability. Parameters within the system are isolated and the system's performance is evaluated with adjustments to parameter sensitivity. The system's performance is evaluated using the probability of detection (POD) and false alarm ratio (FAR) statistics. Of the algorithm parameters tested, sigma-level (metric of lightning jump strength) and flash rate threshold influenced the system's performance the most. Finally, verification methodologies are investigated. It is discovered that minor changes in verification methodology can dramatically impact the evaluation of the lightning jump system.

  17. Automated Storm Tracking and the Lightning Jump Algorithm Using GOES-R Geostationary Lightning Mapper (GLM) Proxy Data

    Science.gov (United States)

    Schultz, Elise; Schultz, Christopher Joseph; Carey, Lawrence D.; Cecil, Daniel J.; Bateman, Monte

    2016-01-01

    This study develops a fully automated lightning jump system encompassing objective storm tracking, Geostationary Lightning Mapper proxy data, and the lightning jump algorithm (LJA), which are important elements in the transition of the LJA concept from a research to an operational based algorithm. Storm cluster tracking is based on a product created from the combination of a radar parameter (vertically integrated liquid, VIL), and lightning information (flash rate density). Evaluations showed that the spatial scale of tracked features or storm clusters had a large impact on the lightning jump system performance, where increasing spatial scale size resulted in decreased dynamic range of the system's performance. This framework will also serve as a means to refine the LJA itself to enhance its operational applicability. Parameters within the system are isolated and the system's performance is evaluated with adjustments to parameter sensitivity. The system's performance is evaluated using the probability of detection (POD) and false alarm ratio (FAR) statistics. Of the algorithm parameters tested, sigma-level (metric of lightning jump strength) and flash rate threshold influenced the system's performance the most. Finally, verification methodologies are investigated. It is discovered that minor changes in verification methodology can dramatically impact the evaluation of the lightning jump system.

  18. Effects of Foam Rolling on Vertical Jump Performance

    Directory of Open Access Journals (Sweden)

    Andrew Jones

    2015-07-01

    Full Text Available Background: Foam rolling is a popular activity utilized by strength and conditioning coaches as it is believed to increase muscle length and break up fibrous adhesions located in connective tissue. However, there is little research investigating the effects of foam rolling on athletic performance. Objective: The purpose of this study was to investigate the effects of lower body foam rolling on vertical jump performance. Methods: Twenty males (age 24.05 ± 2.02 years; height 177.43 ± 6.31 cm; mass 81.41 ± 8.76 kg volunteered to participate. Subjects completed three days of testing, separated by at least twenty-four hours. Day one consisted of baseline vertical jumps on a force plate, followed by familiarization with foam rolling and control protocols. Subjects returned on days two and three and performed 30-second bouts of lower body foam rolling or mimicked foam rolling movements on a skateboard followed by vertical jumps on a force plate. The highest jump from each day was used for statistical analyses. Results: Repeated measures ANOVAs revealed no significant differences in Jump height, impulse, relative ground reaction force, or take-off velocity between conditions. Conclusion: 30-second bouts of lower body foam rolling do not improve vertical jump performance. Keywords: Dynamic Warm-Up, Foam Rolling, Vertical Jump

  19. Motion Planning for Bipedal Robot to Perform Jump Maneuver

    Directory of Open Access Journals (Sweden)

    Xinyang Jiang

    2018-01-01

    Full Text Available The remarkable ability of humans to perform jump maneuvers greatly contributes to the improvements of the obstacle negotiation ability of humans. The paper proposes a jumping control scheme for a bipedal robot to perform a high jump. The half-body of the robot is modeled as three planar links and the motion during the launching phase is taken into account. A geometrically simple motion was first conducted through which the gear reduction ratio that matches the maximum motor output for high jumping was selected. Then, the following strategies to further exploit the motor output performance was examined: (1 to set the maximum torque of each joint as the baseline that is explicitly modeled as a piecewise linear function dependent on the joint angular velocity; (2 to exert it with a correction of the joint angular accelerations in order to satisfy some balancing criteria during the motion. The criteria include the location of ZMP (zero moment point and the torque limit. Using the technique described above, the jumping pattern is pre-calculated to maximize the jump height. Finally, the effectiveness of the proposed method is evaluated through simulations. In the simulation, the bipedal robot model achieved a 0.477-m high jump.

  20. Aerial jumping in the Trinidadian guppy (Poecilia reticulata.

    Directory of Open Access Journals (Sweden)

    Daphne Soares

    Full Text Available Many fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above. The fish jump spontaneously, without being triggered by overt sensory cues, is not migratory and does not attempt to capture aerial food items. Here, we use high speed video imaging to analyze the kinematics of the jumping behavior P. reticulata. Fish jump from a still position by slowly backing up while using its pectoral fins, followed by strong body trusts which lead to launching into the air several body lengths. The liftoff phase of the jump is fast and fish will continue with whole body thrusts and tail beats, even when out of the water. This behavior occurs when fish are in a group or in isolation. Geography has had substantial effects on guppy evolution, with waterfalls reducing gene flow and constraining dispersal. We suggest that jumping has evolved in guppies as a behavioral phenotype for dispersal.

  1. Aerial Jumping in the Trinidadian Guppy (Poecilia reticulata)

    Science.gov (United States)

    Soares, Daphne; Bierman, Hilary S.

    2013-01-01

    Many fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above. The fish jump spontaneously, without being triggered by overt sensory cues, is not migratory and does not attempt to capture aerial food items. Here, we use high speed video imaging to analyze the kinematics of the jumping behavior P. reticulata. Fish jump from a still position by slowly backing up while using its pectoral fins, followed by strong body trusts which lead to launching into the air several body lengths. The liftoff phase of the jump is fast and fish will continue with whole body thrusts and tail beats, even when out of the water. This behavior occurs when fish are in a group or in isolation. Geography has had substantial effects on guppy evolution, with waterfalls reducing gene flow and constraining dispersal. We suggest that jumping has evolved in guppies as a behavioral phenotype for dispersal. PMID:23613883

  2. Biomechanical analysis of squat jump and countermovement jump from varying starting positions.

    Science.gov (United States)

    Mackala, Krzysztof; Stodółka, Jacek; Siemienski, Adam; Coh, Milan

    2013-10-01

    The purpose of this study was to investigate the effect of 2 strategies, defined by foot placement during the initiation of the take-off on performance in vertical jumps. The additional area of interest in this experiment was whether technique of the take-off phase might be an exploratory factor that has different electromyogram (EMG) muscle activity during squat jump (SJ) and countermovement jump (CMJ) performed starting from the standard position, with parallel foot placement, and from the experimental one, with straddle foot placement. Six well-experienced male 100-400 m sprinters, who were members of the Polish youth and senior national team (mean values: age 21.6 years, best performance: 100 m in 10.54 seconds and 400 m in 45.54 seconds), performed vertical SJ and vertical CMJ from 2 initial positions with different foot placement. To collect all selected kinematic and kinetic data, the video recording system BTS Vixta was used in conjunction with force platforms (Kistler model 9286B). The latest system for 3D motion analysis, BTS SMART, based on the passive IR reflective markers was also applied. Electromyograms of 6 lower limb muscles were collected using a Noraxon EMG device. The CMJ was on average 7 cm higher than the SJ (CMJ, 85 cm and SJ, 78 cm), which amounts to 8.97%. This was not because of the increase of center of gravity (COG) velocity at take-off because velocities of center of gravity (COG) projection were almost equal (SJ, 2.93 m·scompared with CMJ, 2.99 m·s). No significant differences of both magnitude and rate of development of the muscle torques and powers between jumps were found, but when we analyzed the problem with division into single legs (right and left) and with division into different jumps (SJ and CMJ), the differences were evident. The profiles of EMG activity of selected muscles showed some differences between SJ and CMJ. The vertical SJ and CMJ performance measurement may be of value to coaches and conditioning specialists who

  3. Optimizing the Distribution of Leg Muscles for Vertical Jumping.

    Directory of Open Access Journals (Sweden)

    Jeremy D Wong

    Full Text Available A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas-which determine the maximum force deliverable by the muscles-constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of

  4. Automated high pressure cell for pressure jump x-ray diffraction

    International Nuclear Information System (INIS)

    Brooks, Nicholas J.; Gauthe, Beatrice L. L. E.; Templer, Richard H.; Ces, Oscar; Seddon, John M.; Terrill, Nick J.; Rogers, Sarah E.

    2010-01-01

    A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

  5. Automated high pressure cell for pressure jump x-ray diffraction.

    Science.gov (United States)

    Brooks, Nicholas J; Gauthe, Beatrice L L E; Terrill, Nick J; Rogers, Sarah E; Templer, Richard H; Ces, Oscar; Seddon, John M

    2010-06-01

    A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

  6. Propulsion efficiency and imposed flow fields of a copepod jump

    DEFF Research Database (Denmark)

    Jiang, H.; Kiørboe, Thomas

    2011-01-01

    the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump...... velocity vectors pointing towards the copepod; such a flow field may inform the predator of the whereabouts of the escaping copepod prey. High Froude propulsion efficiency (0.94–0.98) was obtained for individual power stroke durations of all simulated jumps. This is unusual for small aquatic organisms...

  7. Rate Theory for Correlated Processes: Double Jumps in Adatom Diffusion

    DEFF Research Database (Denmark)

    Jacobsen, J.; Jacobsen, Karsten Wedel; Sethna, J.

    1997-01-01

    We study the rate of activated motion over multiple barriers, in particular the correlated double jump of an adatom diffusing on a missing-row reconstructed platinum (110) surface. We develop a transition path theory, showing that the activation energy is given by the minimum-energy trajectory...... which succeeds in the double jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a root T prefactor for the activated rate of double jumps. Theory and numerical results agree....

  8. The kinematics of swimming and relocation jumps in copepod nauplii

    DEFF Research Database (Denmark)

    Borg, Marc Andersen; Bruno, Eleonora; Kiørboe, Thomas

    2012-01-01

    of pelagic copepods: Temora longicornis, Oithona davisae and Acartia tonsa. The kinematics of jumping is similar between the three species. Jumps result in a very erratic translation with no phase of passive coasting and the nauplii move backwards during recovery strokes. This is due to poorly synchronized......Copepod nauplii move in a world dominated by viscosity. Their swimming-by-jumping propulsion mode, with alternating power and recovery strokes of three pairs of cephalic appendages, is fundamentally different from the way other microplankters move. Protozoans move using cilia or flagella...

  9. The Perpetual American Put Option for Jump-Diffusions

    OpenAIRE

    Aase, Knut K.

    2010-01-01

    -This is the author's version of the article"The Perpetual American Put Option for Jump-Diffusions" Energy Systems pp 493-507. We solve a specific optimal stopping problem with an infinite time horizon, when the state variable follows a jump-diffusion. The novelty of the paper is related to the inclusion of a jump component in this stochastic process. Under certain conditions, our solution can be interpreted as the price of an American perpetual put option. We characterize the continuation...

  10. Aeromechanics of the Spider Cricket Jump: How to Jump 60+ Times Your Body Length and Still Land on Your Feet

    Science.gov (United States)

    Palmer, Emily; Deshler, Nicolas; Gorman, David; Neves, Catarina; Mittal, Rajat

    2015-11-01

    Flapping, gliding, running, crawling and swimming have all been studied extensively in the past and have served as a source of inspiration for engineering designs. In the current project, we explore a mode of locomotion that straddles ground and air: jumping. The subject of our study is among the most proficient of long-jumpers in Nature: the spider cricket of the family Rhaphidophoridae, which can jump more than 60 times its body length. Despite jumping this immense distance, these crickets usually land on their feet, indicating an ability to control their posture during ``flight.'' We employ high-speed videogrammetry, to examine the jumps and to track the crickets' posture and appendage orientation throughout their jumps. Simple aerodynamic models are developed to predict the aerodynamic forces and moment on the crickets during `flight`. The analysis shows that these wingless insects employ carefully controlled and coordinated positioning of the limbs during flight so as to increase jump distance and to stabilize body posture during flight. The principles distilled from this study could serve as an inspiration for small jumping robots that can traverse complex terrains.

  11. USEFULNESS AND METABOLIC IMPLICATIONS OF A 60-SECOND REPEATED JUMPS TEST AS A PREDICTOR OF ACROBATIC JUMPING PERFORMANCE IN GYMNASTS

    Directory of Open Access Journals (Sweden)

    Ferran Antoni Rodriguez

    2013-01-01

    Full Text Available Gymnastics floor exercises are composed of a set of four to five successive acrobatic jumps usually called a �series�. The aims of the study were: 1 to relate the acrobatic gymnastics performance of these series with a repeated jumps test of similar duration (R60, 2 to study the relation between R60 and physiological parameters (heart rate and blood lactate, and the performance obtained in different kinds of jumps, 3 to confirm whether R60, executed without a damped jumping technique, can be considered an anaerobic lactic power test. Twenty male and twenty-four female gymnasts performed three repeated jumps tests for 5 s (R5, 10 s (R10 and 60 s (R60 and vertical jumps, such as drop jumps (DJ, squat jumps (SJ and countermovement jumps (CMJ. We assessed heart rate (HR and blood lactate during R10 and R60. The average values of the maximal blood lactate concentration (Lmax after R10 (males = 2.5±0.6 mmol.l-1; females = 2.1±0.8 mmol.l-1 confirm that anaerobic glycolysis is not activated to a high level. In R60, the Lmax (males = 7.5±1.7 mmol.l-1; females = 5.9±2.1 mmol.l-1 that was recorded does not validate R60 as an anaerobic lactic power test. We confirmed the relation between the average power obtained in R60 (R60Wm and the acrobatic performance on the floor. The inclusion in the multiple regression equation of the best power in DJ and the best flight-contact ratio (FC in R5 confirms the influence of other non-metabolic components on the variability in R60 performance, at least in gymnasts.

  12. Ankle stabilizers affect agility but not vertical jump or dynamic balance performance.

    Science.gov (United States)

    Ambegaonkar, Jatin P; Redmond, Charles J; Winter, Christa; Cortes, Nelson; Ambegaonkar, Shruti J; Thompson, Brian; Guyer, Susan M

    2011-12-01

    Ankle stabilizers can reduce ankle sprain incidence and severity by limiting range of motion. Still whether using them affects performance remains unclear. The authors compared effects of 3 ankle stabilizers, tape, lace-up (Swede-O Ankle Lok), and semirigid (Air-Cast Air-Stirrup) braces, and a nonsupport control on vertical jump (Sargent Jump Test), agility (Right-Boomerang Run test), and dynamic balance (Modified Bass Test) in 10 volunteers (4 males, 6 females; 25.6 ± 2.8 years, 167.8 ± 13.7 cm, 61.4 ± 10.7 kg) using repeated-measures ANOVAs. Participants had similar vertical jump (P = .27; control = 41.40 ± 11.89 cm, tape = 37.90 ± 7.92 cm, Swede-O = 41.40 ± 11.89 cm, Air-Cast = 39.29 ± 10.85 cm) and dynamic balance (P = .08; control = 92.50 ± 2.46, tape = 91.55 ± 3.53, Swede-O = 97.00 ± 5.32, Air-Cast = 89.40 ± 6.08) but differing agility scores (P = .03; control = 13.55 ± 1.35 seconds, tape = 14.03 ± 1.5 seconds, Swede-O = 14.10 ± 1.36 seconds, Air-Cast = 14.14 ± 1.41 seconds). Post hoc tests revealed a significant difference (P = .03) between control and Air-Cast but not between Swede-O (P = .06) or tape (P = .07). Effect size (d) analyses indicated that compared with control, all stabilizers trended to increase agility run times (tape, d = 0.33; Swede-O, d = 0.40; Air-Cast, d = 0.43). Since participants primarily required sagittal plane motion when jumping vertically and had relatively slow directional changes in the dynamic balance test, wearing ankle stabilizers did not hamper jump or balance. However, ankle stabilizers hindered participants' ability to perform quick directional changes required in the agility test, with the most rigid stabilizer (Air-Cast) affecting agility the most. Clinicians should be aware that ankle stabilizers may affect some performance measures (agility) but not others (jumping, balance) and continue examinations in larger cohorts. Therapeutic, Level II.

  13. How do elite ski jumpers handle the dynamic conditions in imitation jumps?

    NARCIS (Netherlands)

    Ettema, G.J.; Hooiveld, J; Braaten, S; Bobbert, M.F.

    2016-01-01

    ABSTRACT: We examined the effect of boundary conditions in imitation ski jumping on movement dynamics and coordination. We compared imitation ski jumps with – and without – the possibility to generate shear propulsion forces. Six elite ski jumpers performed imitation jumps by jumping from a fixed

  14. Safer Ski Jumps: Design of Landing Surfaces and Clothoidal In-Run Transitions

    Science.gov (United States)

    2010-06-01

    1 A. AN ABBREVIATED HISTORY OF SKIING ............................................ 1 B. THE RISE OF FREESTYLE SKIING...JUMPING A. AN ABBREVIATED HISTORY OF SKIING Skiing is one of the oldest sports in human history . The earliest known accounts of skiing occurred...skiing, racing, ski ballet , jibbing, powder skiing, aerials, ski jumping, skiercross, and others. 2 1. Olympic Jumps and Aerials Ski jumping gained

  15. Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method)

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

    Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf......Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf...

  16. A comparison of one-legged and two-legged countermovement jumps

    NARCIS (Netherlands)

    van Soest, A J; Roebroeck, M.E.; Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    1985-01-01

    Ten well-trained male volleyball players performed one-legged and two-legged vertical countermovement jumps. Ground reaction forces, cinematographic data, and electromyographic data were recorded. Jumping height in one-legged jumps was 58.5% of that reached in two-legged jumps. Mean net torques in

  17. Hiding information in open auctions with jump bids

    Czech Academy of Sciences Publication Activity Database

    Ettinger, D.; Michelucci, Fabio

    2016-01-01

    Roč. 126, č. 594 (2016), s. 1484-1502 ISSN 0013-0133 Institutional support: RVO:67985998 Keywords : hiding information * open auctions * jump bids Subject RIV: AH - Economics Impact factor: 2.608, year: 2016

  18. METRIC TESTS CHARACTERISTIC FOR ESTIMATING JUMPING FOR VOLLEYBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Toplica Stojanović

    2008-08-01

    Full Text Available With goal to establish metric tests characteristics for estimating jumping for volleyball players, it was organized a pilot research on pattern of 23 volleyball players from cadet team and 23 students from high-school. For needs of this research four tests are valid for estimation, jump in block with left and right leg and jump in spike with left and right leg. Each test has been taken three times, so that we could with test-re test method determine their reliability, and with factor analysis their validity. Data were processed by multivariate analysis (item analysis, factor analysis from statistical package „Statistica 6.0 for windows“. On the results of research and discussion we can say that the tests had high coefficient of reliability, as well as factor validity, and these tests can be used to estimate jumping for volleyball players.

  19. Swarm algorithms with chaotic jumps for optimization of multimodal functions

    Science.gov (United States)

    Krohling, Renato A.; Mendel, Eduardo; Campos, Mauro

    2011-11-01

    In this article, the use of some well-known versions of particle swarm optimization (PSO) namely the canonical PSO, the bare bones PSO (BBPSO) and the fully informed particle swarm (FIPS) is investigated on multimodal optimization problems. A hybrid approach which consists of swarm algorithms combined with a jump strategy in order to escape from local optima is developed and tested. The jump strategy is based on the chaotic logistic map. The hybrid algorithm was tested for all three versions of PSO and simulation results show that the addition of the jump strategy improves the performance of swarm algorithms for most of the investigated optimization problems. Comparison with the off-the-shelf PSO with local topology (l best model) has also been performed and indicates the superior performance of the standard PSO with chaotic jump over the standard both using local topology (l best model).

  20. Trading price jump clusters in foreign exchange markets

    Czech Academy of Sciences Publication Activity Database

    Novotný, Jan; Petrov, D.; Urga, G.

    2015-01-01

    Roč. 24, June (2015), s. 66-92 ISSN 1386-4181 Institutional support: PRVOUK-P23 Keywords : price jumps * foreign exchange markets * trading Subject RIV: AH - Economics Impact factor: 1.726, year: 2015

  1. Hiding information in open auctions with jump bids

    Czech Academy of Sciences Publication Activity Database

    Ettinger, D.; Michelucci, Fabio

    2016-01-01

    Roč. 126, č. 594 (2016), s. 1484-1502 ISSN 0013-0133 Institutional support: PRVOUK-P23 Keywords : hiding information * open auctions * jump bids Subject RIV: AH - Economics Impact factor: 2.608, year: 2016

  2. PERBANDINGAN JUMP SHOOT DENGAN AWALAN DAN TANPA AWALAN TERHADAP PENINGKATAN KETEPATAN SHOOTING DALAM PERMAINAN BOLABASKET

    OpenAIRE

    I Gusti Ngurah Agung Cahya Prananta; N. Adiputra; I P G Adiatmika

    2015-01-01

    The effectiveness of  jump-shoot technique step jump shoot and still jump shoot in a game is still questionable,  because many different assumptions arise. One opinion stated that step jump shoot was more effective and the other stated that and still jump shoot was more efective. Therefore it is necessary to do research on the analysis of the results of step jump shoot and and still jump shoot to improve the accuracy of shooting in a basketball. The experimental research had been conducted on...

  3. Knee Muscular Control During Jump Landing in Multidirections

    OpenAIRE

    Sinsurin; Vachalathiti; Jalayondeja; Limroongreungrat

    2016-01-01

    Background Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. Objectives The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direct...

  4. Temperature Jump Pyrolysis Studies of RP 2 Fuel

    Science.gov (United States)

    2017-01-09

    Briefing Charts 3. DATES COVERED (From - To) 15 December 2016 – 11 January 2017 4. TITLE AND SUBTITLE Temperature Jump Pyrolysis Studies of RP-2 Fuel...Rev. 8- 98) Prescribed by ANSI Std. 239.18 1 TEMPERATURE JUMP PYROLYSIS STUDIES OF RP-2 FUEL Owen Pryor1, Steven D. Chambreau2, Ghanshyam L...Mixture Distribution A: Approved for public release; distribution unlimited. PA Clearance 17026 4 RP-2 Pyrolysis /Combustion Chemistries? • Recent

  5. Spinal column damage from water ski jumping

    Energy Technology Data Exchange (ETDEWEB)

    Horne, J.; Cockshott, W.P.; Shannon, H.S.

    1987-11-01

    We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children. (orig.)

  6. Hydraulic jumps in the liquid foam microchannels

    Science.gov (United States)

    Raufaste, Christophe; Cohen, Alexandre; Fraysse, Nathalie; Rajchenbach, Jean; Bouret, Yann; Argentina, Mederic

    2017-11-01

    Plateau borders (PBs) are the liquid microchannels found at the intersection between three bubbles in liquid foams. They form an interconnected network that plays a major role in foam drainage and stability properties. Each channel has an unbounded geometry but is not subject to the Rayleigh-Plateau instability. This stability is accounted for by an effective negative surface tension (Géminard et al., 2004). We show that their relaxation dynamics can trigger inertial flows characterized by strongly nonlinear features. An experimental setup was designed to study the response of a PB to a liquid perturbation. Extra liquid is injected into the PB by drop coalescence. Depending on the parameters, either a viscous flow or an inertial one is observed. For the latter, the relaxation takes the form of a hydraulic jump, which propagates at a velocity around 0.1-1 m/s. Solitons are also observed for another type of perturbation. The PB dynamics is modeled and its equation presents an analogy with the differential equation of mechanical nonlinear oscillators.

  7. Spinal column damage from water ski jumping.

    Science.gov (United States)

    Horne, J; Cockshott, W P; Shannon, H S

    1987-01-01

    We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children.

  8. Spinal column damage from water ski jumping

    International Nuclear Information System (INIS)

    Horne, J.; Cockshott, W.P.; Shannon, H.S.

    1987-01-01

    We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children. (orig.)

  9. Changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint.

    Science.gov (United States)

    Caulfield, Brian; Garrett, Mary

    2004-07-01

    To identify changes in ground reaction force during jump landing in subjects with functional instability of the ankle joint. Comparison of ground reaction force during jump landing between subjects with functional instability and healthy controls. We have recently demonstrated significantly altered patterns of ankle and knee movement immediately pre- and post-impact in subjects with functional instability compared to healthy controls. We now examine the changes in timing and magnitude of forces sustained by the unstable ankle during jump landing. Fourteen subjects with unstable ankles and 10 age, sex and activity matched controls performed five single leg jumps onto a force platform whilst ground reaction forces were sampled. Timing and magnitudes of forces during the first 150 ms following impact were analysed and compared between groups. Lateral and anterior force peaks occurred significantly earlier in subjects with functional instability. Significant differences were seen between groups' time-averaged vertical, frontal and sagittal components of ground reaction force. These ranged from 5% (frontal force) to 100% (vertical force) of body mass. These changes occur immediately post-impact and too early for reflex correction/modification. The disordered force patterns observed in subjects with functional instability are likely to result in repeated injury due to significant increase in stress on ankle joint structures during jump landing. We suggest that they are most likely to result from deficits in feed-forward motor control. These results identify the potentially injurious nature of the changes in the forces applied to the unstable ankle joint during jump landing. The timing of these changes suggests that they are caused by a motor control deficit. Treatment approaches aimed at retraining feed-forward control of ankle joint movement could succeed in restoring more normal patterns of force absorption and reduce the occurrence of repeated micro-trauma to ankle

  10. Kinetic asymmetries between forward and drop jump landing tasks

    Directory of Open Access Journals (Sweden)

    Morgana Alves de Britto

    2015-12-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n6p661   Landing asymmetry is a risk factor for knee anterior cruciate ligament injury. The aim of this study was to identify kinetic asymmetries in healthy recreational athletes performing different jump-landing techniques. Twelve recreational athletes engaged in regular training underwent kinetic evaluation using two 3D force plates and were analyzed for: (a three-dimensional peak forces, (b time to peak vertical force, and (c initial phase asymmetries. All data were collected during performance of unilateral and bilateral trials of forward and drop jump tasks. Forward jump-landing tasks elicited greater kinetic asymmetry than drop-landing tasks. Regardless of jump-landing technique, the preferred leg experienced higher forces than the non-preferred leg. The initial landing phase showed more kinetic asymmetries than the later phase when peak vertical forces occur. It was concluded that when screening athletes for kinetic asymmetries that may predispose them to injury, forward jump-landing tasks and the early landing phase might show more kinetic asymmetries than drop jump-landing tasks and the late landing phase, respectively.

  11. RHIC GAMMA TRANSITION JUMP POWER SUPPLY PROTOTYPE TEST

    International Nuclear Information System (INIS)

    MI, J.; GANETIS, G.; LOUIE, W.; BRUNO, D.; ZAPASEK, R.; SANDBERG, J.; ZHANG, W.

    2001-01-01

    This paper describes the principle and test results of the prototype RHIC Gamma Transition Jump Power Supply. The jump power supply principle is introduced and illustrated along with diagrams in this paper. The prototype is built with Insulated Gate Bipolar Transistors (IGBT) as current direction switch components. Optically coupled IGBT drivers are used for the jump control switch. The jump time among the power supplies is synchronized from 40 to 60 milliseconds to meet the RHIC beam transition-crossing requirement. The short jump time is needed to avoid particle loss and to preserve the initial bunch area during the transition, thus successfully transferring the ion beams from the acceleration RF system to storage system. There are a total of twenty four jump power supplies that will be used. They synchronously switch the direction of the magnets current while the beam is being accelerated through the transition to reach the top storage energy. Each power supply will energize a group of super conducting magnets, which consists of four magnets that are connected in series. At the end, test results are listed, accompanied with the dummy load current waveform and prototype power supply picture

  12. the Modeling of Hydraulic Jump Generated Partially on Sloping Apron

    Directory of Open Access Journals (Sweden)

    Shaker Abdulatif Jalil

    2017-12-01

    Full Text Available Modeling aims to characterize system behavior and achieve simulation close as possible of the reality. The rapid energy exchange in supercritical flow to generate quiet or subcritical flow in hydraulic jump phenomenon is important in design of hydraulic structures. Experimental and numerical modeling is done on type B hydraulic jump which starts first on sloping bed and its end on horizontal bed.  Four different apron slopes are used, for each one of these slopes the jump is generated on different locations by controlling the tail water depth.  Modelling validation is based on 120 experimental runs which they show that there is reliability. The air volume fraction which creates in through hydraulic jump varied between 0.18 and 0.28. While the energy exchanges process take place within 6.6, 6.1, 5.8, 5.5 of the average relative jump height for apron slopes of 0.18, 0.14, 0.10, 0.07 respectively. Within the limitations of this study, mathematical prediction model for relative hydraulic jump height is suggested.The model having an acceptable coefficient of determination.

  13. Origin of the B jump observed in precision liner experiments

    International Nuclear Information System (INIS)

    Lee, H.; Stokes, J.L.; Broste, W.B.

    1995-01-01

    In the liner-ejecta experiments carried out at the Los Alamos pulsed power facility Pegasus II, a solid liner was magnetically imploded to impact on a target cylinder to produce the shock-induced ejecta. As a result of improved time resolution for the B (dB/dt) probes fielded last fall, the authors began to notice a sharp jump in the B curve occurring at a time very close to the expected liner-target collision time. This jump was also found in the time derivative of the calculated current (dI/dt) obtained from code simulation. They have shown that the jump is indeed caused by the collision as a sudden change of the liner velocity would induce a sudden jump in the time derivative of the inductance. They have derived a general formula for calculating the jump in dI/dt and verified that the result computed from it is in good agreement with the code simulation. Useful diagnostic applications of the B jump are discussed. This paper is relevant for magnetized target fusion

  14. Kinematic structure at the early flight position in ski jumping.

    Science.gov (United States)

    Vodičar, Janez; Coh, Milan; Jošt, Bojan

    2012-12-01

    The purpose of our research was to establish the variability of correlation between the length of the jumps and selected multi-item kinematic variables (n=9) in the early flight phase technique of ski jumping. This study was conducted on a sample of elite Slovenian ski jumpers (N=29) who participated in the experiment on a jumping hill in Hinterzarten, Germany (HS95m) on the 20(th) of August, 2008. The highest and most significant correlations (p=0.01) with the length of the ski jump were found in the multi-item variable height of flying, which was also expressed with the highest level of stability of the explained total variance (TV) on the first factor (TV=69.13%). The most important characteristic of the aerodynamic aspect of early flight was the variable angle between the body chord and the horizontal axis with significantly high correlations (pjump. Only two more variables, the angle between the upper body and the horizontal plane (TV=53.69%), and the angle between left ski and left leg (TV=50.13%), had an explained common variance on the first factor greater than 50% of total variance. The results indicated that some kinematic parameters of ski jumping early flight technique were more important for success considering the length of the jump.

  15. Jump percentile: a proposal for evaluation of high level sportsmen.

    Science.gov (United States)

    Centeno-Prada, R A; López, C; Naranjo-Orellana, J

    2015-05-01

    The goal of this study was to determine reference values of explosive strength for Spanish professional athletes using a force platform. Reference values are displayed as a sports-independent percentile distribution. A total of 323 elite male athletes (age: 20.38 ± 4.65 years, body mass: 75.04 ± 14.30 kg, height: 178.62 ± 14.18 cm) from different disciplines performed the following test: squat jump (SJ), countermovement jump (CMJ), Abalakov test (AB), drop jump (DJ) and repeated jumps (RJ). We calculated: relative peak power, relative peak force, maximal height, symmetry index, explosive index of strength, relative effective impulse, duration of jump, elastic capacity, eccentric time, action of arm, jump number, average height, intensity and fatigue index of force. Significant differences were found among sports disciplines (Pdisciplines in DJ variables. In RJ, the main variable characterizing the disciplines analyzed was average height, which showed a significant negative association with athletics, soccer, volleyball and gymnastics. The results obtained suggest that a percentile table may be useful in assessing explosive strength in athletes, regardless of there being any reference values available for their sports discipline.

  16. Effects of countermovement depth on kinematic and kinetic patterns of maximum vertical jumps.

    Science.gov (United States)

    Mandic, Radivoj; Jakovljevic, Sasa; Jaric, Slobodan

    2015-04-01

    Although maximum height (H(max)), muscle force (F), and power output (P), have been routinely obtained from maximum vertical jumps for various purposes, a possible role of the countermovement depth (H(cmd)) on the same variables remains largely unexplored. Here we hypothesized that (1) the optimum H(cmd) for maximizing H(max) exists, while (2) an increase in H(cmd) would be associated with a decrease in both F and P. Professional male basketball players (N=11) preformed maximum countermovement jumps with and without arm swing while varying H(cmd)±25 cm from its preferred value. Although regression models revealed a presence of optimum H(cmd) for maximizing H(max), H(max) revealed only small changes within a wide range of H(cmd). The preferred H(cmd) was markedly below its optimum value (p vertical jumps should be taken with caution since both of them could be markedly confounded by H(cmd). Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Genetic Variability of Show Jumping Attributes in Young Horses Commencing Competing

    Directory of Open Access Journals (Sweden)

    Tomasz Próchniak

    2015-08-01

    Full Text Available The aim of the study was to select traits that may constitute a prospective criterion for breeding value prediction of young horses. The results of 1,232 starts of 894 four-, five-, six-, and seven-year-old horses, obtained during jumping championships for young horses which had not been evaluated in, alternative to championships, training centres were analyed. Nine traits were chosen of those recorded: ranking in the championship, elimination (y/n, conformation, rating of style on day one, two, and three, and penalty points on day one, two, and three of a championship. (Covariance components were estimated via the Gibbs sampling procedure and adequate (covariance component ratios were calculated. Statistical classifications were trait dependent but all fitted random additive genetic and permanent environment effects. It was found that such characteristics as penalty points and jumping style are potential indicators of jumping ability, and the genetic variability of the traits was within the range of 14% to 27%. Given the low genetic correlations between the conformation and other results achieved on the parkour, the relevance of assessment of conformation in four-years-old horses has been questioned.

  18. Numerical investigation of the early flight phase in ski-jumping.

    Science.gov (United States)

    Gardan, N; Schneider, A; Polidori, G; Trenchard, H; Seigneur, J M; Beaumont, F; Fourchet, F; Taiar, R

    2017-07-05

    The purpose of this study is to develop a numerical methodology based on real data from wind tunnel experiments to investigate the effect of the ski jumper's posture and speed on aerodynamic forces in a wide range of angles of attack. To improve our knowledge of the aerodynamic behavior of the ski jumper and his equipment during the early flight phase of the ski jump, we applied CFD methodology to evaluate the influence of angle of attack (α=14°, 21.5°, 29°, 36.5° and 44°) and speed (u=23, 26 and 29m/s) on aerodynamic forces in the situation of stable attitude of the ski jumper's body and skis. The standard k-ω turbulence model was used to investigate both the influence of the ski jumper's posture and speed on aerodynamic performance during the early flight phase. Numerical results show that the ski jumper's speed has very little impact on the lift and drag coefficients. Conversely, the lift and drag forces acting on the ski jumper's body during the early flight phase of the jump are strongly influenced by the variations of the angle of attack. The present results suggest that the greater the ski jumper's angle of inclination, with respect to the relative flow, the greater the pressure difference between the lower and upper parts of the skier. Further studies will focus on the dependency of the parameters with both the angle of attack α and the body-ski angle β as control variables. It will be possible to test and optimize different ski jumping styles in different ski jumping hills and investigate different environmental conditions such as temperature, altitude or crosswinds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Acute Effects Of Active, Ballistic, Passive And Proprioceptive Neuromuscular Facilitation Streching On Sprint And Vertical Jump Performance In Trained Young Soccer Players.

    Science.gov (United States)

    de Paula Oliveira, Lucas; Palucci Vieira, Luiz Henrique; Aquino, Rodrigo; Vieira Manechini, João Paulo; Pereira Santiago, Paulo Roberto; Puggina, Enrico Fuini

    2017-10-27

    The aim of the present study was to compare the acute effects of active (AC), ballistic (BA), passive (PA), proprioceptive neuromuscular facilitation stretching (PNF) methods on performance in vertical jumping, sit and reach, and sprinting in young soccer players. Twelve trained soccer players (17.67 ± 0.87 years) participated in the study. The jump height (H), peak power (PP), and relative power (RP) in the squat jump (SJ) and countermovement jump (CMJ), the range of motion (ROM), the rate of perceived exertion (RPE), and time (s) in 10-20-30 m sprints were evaluated. Significant differences (p <0.05) in H were found in the comparisons between the PA and control condition (CO) for the SJ. For the CMJ, differences in H were observed between the PA and CO, and PNF with CO and BA, and in the PP between the PNF and CO, AC, and BA, as well as in the RP between the PNF and BA. Significant increases in ROM were found in the AC, BA, PA, and PNF, compared to the CO. In relation to RPE, higher scores were reported in the PA and PNF conditions compared to the AC and BA. No significant differences were found in 10-20-30 m sprints. Therefore, the AC and BA methods can be used prior to vertical jump and sprint activities, with the aim of increasing flexibility. However, the PA and PNF methods should be avoided, due to subsequent negative effects on vertical jump performance.

  20. Jumping for Fun? Negotiating Mobility and the Geopolitics of Foursquare

    Directory of Open Access Journals (Sweden)

    Germaine R. Halegoua

    2016-08-01

    Full Text Available Rather than assume that there is some universal “right way” to engage social media platforms, we interrogate how the location-based social media practice known as “jumping” played out on the popular service Foursquare. We use this case to investigate how a “global” or universal system is constructed with an imagined user in mind, one who enjoys a particular type of mobility and experience of place. Through the analysis of official Foursquare policies and mission statements, discussions among developers, interviews with and conversations among Foursquare users, online traces left by jumpers, and correspondence between designers and users on discussion forums, we identify how certain practices and participants are discursively constructed as normative, while other practices and groups are marginalized. Through the study of “jumping,” and its association with Indonesian players in particular, we highlight tensions between the assumptions and industrial strategies of Foursquare designers and the emergent practices and norms of early adopters and avid participants. We argue that the practices of “Indonesian” Foursquare jumpers and the discourses surrounding their use of Foursquare illustrate that practices understood as transgressive or resistive might best be read as strategies for engaging with a platform as groups contend with marginalizing social, economic, and/or political conditions. The case study examined in this article highlights the practices of participants who attempt to integrate themselves into the design of a social media system and the “workarounds,” tensions, negotiations, and logics that manifest in that process.

  1. Insulin Resistance and Prediabetes

    Science.gov (United States)

    ... in the normal range. What happens with insulin resistance? In insulin resistance, muscle, fat, and liver cells do not ... they do not usually test specifically for insulin resistance. Insulin resistance can be assessed by measuring the level ...

  2. Studies on Foam Decay Trend and Influence of Temperature Jump on Foam Stability in Sclerotherapy.

    Science.gov (United States)

    Bai, Taoping; Chen, Yu; Jiang, Wentao; Yan, Fei; Fan, Yubo

    2018-02-01

    This study investigated the influence of temperature jump and liquid-gas ratio on foam stability to derive the foam-decay law. The experimental group conditions were as follows: mutation temperatures (10°C, 16°C, 20°C, 23°C, 25°C, and 27°C to >37°C) and liquid-gas ratios (1:1, 1:2, 1:3, and 1:4). The control group conditions were as follows: temperatures (10°C, 16°C, 20°C, 23°C, 25°C and 27°C) and liquid-gas ratios (1:1, 1:2, 1:3, and 1:4). A homemade device manufactured using the Tessari DSS method was used to prepare the foam. The decay process was videotape recorded. In the drainage rate curve, the temperature rose, and the liquid-gas ratio varied from 1:1 to 1:4, causing faster decay. In the entire process, the foam volume decreased with increasing drainage rate. The relationships were almost linear. Comparison of the experimental and control groups shows that the temperature jump results in a drainage time range of 1 to 15 seconds. The half-life ranges from 10 to 30 seconds. The maximum rate is 18.85%. Changes in the preparation temperature yields a drainage time range of 3 to 30 seconds. The half-life varies from 20 to 60 seconds. Decreasing the temperature jump range and liquid-gas ratio gradually enhances the foam stability. The foam decay time and drainage rate exhibit an exponential function distribution.

  3. The validity and reliability of an iPhone app for measuring vertical jump performance.

    Science.gov (United States)

    Balsalobre-Fernández, Carlos; Glaister, Mark; Lockey, Richard Anthony

    2015-01-01

    The purpose of this investigation was to analyse the concurrent validity and reliability of an iPhone app (called: My Jump) for measuring vertical jump performance. Twenty recreationally active healthy men (age: 22.1 ± 3.6 years) completed five maximal countermovement jumps, which were evaluated using a force platform (time in the air method) and a specially designed iPhone app. My jump was developed to calculate the jump height from flight time using the high-speed video recording facility on the iPhone 5 s. Jump heights of the 100 jumps measured, for both devices, were compared using the intraclass correlation coefficient, Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation and Bland-Altman plots. There was almost perfect agreement between the force platform and My Jump for the countermovement jump height (intraclass correlation coefficient = 0.997, P iPhone 5 s app.

  4. The effect of strength training, recreational soccer and running exercise on stretch-shortening cycle muscle performance during countermovement jumping

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Randers, Morten Bredsgaard

    2012-01-01

    ) and muscle fiber size (CSA) were studied in untrained individuals (n=49, 21-45yrs) pre and post 12weeks of progressive heavy-resistance strength training (ST, n=8), recreational soccer training (SOC, n=15), high-intensity interval running (INT, n=7), continuous running (RUN, n=9) or continuation...... production, indicating a more explosive-type SSC muscle performance. No effects were detected in CMJ performance after continuous running, high-intensity interval running and recreational soccer, despite an increased muscle fiber CSA and quadriceps muscle activity in SOC. Enhanced neuromuscular activity......The purpose of the present study was to evaluate the effect of contrasting training modalities on mechanical muscle performance and neuromuscular activity during maximal SSC (stretch-shortening cycle) countermovement jumps (CMJ). Bilateral countermovement jumping, surface electromyography (EMG...

  5. Bayesian inference for Markov jump processes with informative observations.

    Science.gov (United States)

    Golightly, Andrew; Wilkinson, Darren J

    2015-04-01

    In this paper we consider the problem of parameter inference for Markov jump process (MJP) representations of stochastic kinetic models. Since transition probabilities are intractable for most processes of interest yet forward simulation is straightforward, Bayesian inference typically proceeds through computationally intensive methods such as (particle) MCMC. Such methods ostensibly require the ability to simulate trajectories from the conditioned jump process. When observations are highly informative, use of the forward simulator is likely to be inefficient and may even preclude an exact (simulation based) analysis. We therefore propose three methods for improving the efficiency of simulating conditioned jump processes. A conditioned hazard is derived based on an approximation to the jump process, and used to generate end-point conditioned trajectories for use inside an importance sampling algorithm. We also adapt a recently proposed sequential Monte Carlo scheme to our problem. Essentially, trajectories are reweighted at a set of intermediate time points, with more weight assigned to trajectories that are consistent with the next observation. We consider two implementations of this approach, based on two continuous approximations of the MJP. We compare these constructs for a simple tractable jump process before using them to perform inference for a Lotka-Volterra system. The best performing construct is used to infer the parameters governing a simple model of motility regulation in Bacillus subtilis.

  6. Mechanical parameters and flight phase characteristics in aquatic plyometric jumping.

    Science.gov (United States)

    Louder, Talin J; Searle, Cade J; Bressel, Eadric

    2016-09-01

    Plyometric jumping is a commonly prescribed method of training focused on the development of reactive strength and high-velocity concentric power. Literature suggests that aquatic plyometric training may be a low-impact, effective supplement to land-based training. The purpose of the present study was to quantify acute, biomechanical characteristics of the take-off and flight phase for plyometric movements performed in the water. Kinetic force platform data from 12 young, male adults were collected for counter-movement jumps performed on land and in water at two different immersion depths. The specificity of jumps between environmental conditions was assessed using kinetic measures, temporal characteristics, and an assessment of the statistical relationship between take-off velocity and time in the air. Greater peak mechanical power was observed for jumps performed in the water, and was influenced by immersion depth. Additionally, the data suggest that, in the water, the statistical relationship between take-off velocity and time in air is quadratic. Results highlight the potential application of aquatic plyometric training as a cross-training tool for improving mechanical power and suggest that water immersion depth and fluid drag play key roles in the specificity of the take-off phase for jumping movements performed in the water.

  7. Jump point detection for real estate investment success

    Science.gov (United States)

    Hui, Eddie C. M.; Yu, Carisa K. W.; Ip, Wai-Cheung

    2010-03-01

    In the literature, studies on real estate market were mainly concentrating on the relation between property price and some key factors. The trend of the real estate market is a major concern. It is believed that changes in trend are signified by some jump points in the property price series. Identifying such jump points reveals important findings that enable policy-makers to look forward. However, not all jump points are observable from the plot of the series. This paper looks into the trend and introduces a new approach to the framework for real estate investment success. The main purpose of this paper is to detect jump points in the time series of some housing price indices and stock price index in Hong Kong by applying the wavelet analysis. The detected jump points reflect to some significant political issues and economic collapse. Moreover, the relations among properties of different classes and between stocks and properties are examined. It can be shown from the empirical result that a lead-lag effect happened between the prices of large-size property and those of small/medium-size property. However, there is no apparent relation or consistent lead in terms of change point measure between property price and stock price. This may be due to the fact that globalization effect has more impact on the stock price than the property price.

  8. CONNECTION OF FUNCTIONAL ABILITIES WITH JUMPING AND THROWING ATHLETIC DISCIPLINES

    Directory of Open Access Journals (Sweden)

    Igor Stanojević

    2014-06-01

    Full Text Available The aim of this study was to determine the connection between functional abilities with results of jumping and throwing athletic disciplines with athletes. The sample was taken from a population of elementary school students from Prokuplje region, 13 and 14 old, included in regular physical education classes. The sample consisted of 200 male athletes involved in the training process in sports clubs at least three times a week in addition to physical education classes. For assessment of functional abilities six functional tests were used: resting heart rate, Cooper test, heart rate in the first minute after Cooper test, heart rate in the second minute after Cooper test, systolic arterial blood pressure, diastolic arterial blood pressure. For assessment of jumping and throwing athletic disciplines four tests were used: long jump, high jump, shot put and javelin. Data analysis was performed with canonical correlation and regression analysis. The results showed a statistically significant correlation between functional abilities with all of tests in jumping and throwing athletic disciplines.

  9. Automated correction of unwanted phase jumps in reference signals which corrupt MRSI spectra after eddy current correction

    Science.gov (United States)

    Simonetti, A. W.; Melssen, W. J.; van der Graaf, M.; Heerschap, A.; Buydens, L. M. C.

    2002-12-01

    A commonly applied step in the postprocessing of gradient localized proton MR spectroscopy, is correction for eddy current effects using the water signal as a reference. However, this method can degrade some of the metabolite signals, in particular if applied on proton MR spectroscopic imaging data. This artifact arises from the water reference signal in the presence of a second signal which resonates close to the main water resonance. The interference of both resonances will introduce jumps in the phase of the reference time domain signal. Using this phase for eddy current correction will result in a ringing artifact in the frequency domain of the metabolite signal over the whole frequency range. We propose a moving window correction algorithm, which screens the phase of reference signals and removes phase jumps in time domain caused by interference of signals from multiple spin systems. The phase jumps may be abrupt or gradually distributed over several time data points. Because the correction algorithm only corrects time data points which contain phase jumps, the phase is minimally disrupted. Furthermore, the algorithm is automated for large datasets, correcting only those water reference signals which are corrupted. After correction of the corrupted reference signals, normal eddy current correction may be performed. The algorithm is compared with a method which uses a low-pass filter and tested on simulated data as well as on in vivo proton spectroscopic imaging data from a healthy volunteer and from patients with a brain tumor.

  10. Force generation examined by laser temperature-jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres.

    Science.gov (United States)

    Ranatunga, K W; Coupland, M E; Pinniger, G J; Roots, H; Offer, G W

    2007-11-15

    We examined the tension change induced by a rapid temperature jump (T-jump) in shortening and lengthening active muscle fibres. Experiments were done on segments of permeabilized single fibres (length (L0) approximately 2 mm, sarcomere length 2.5 microm) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1, ionic strength 200 mm and temperature approximately 9 degrees C. A fibre was maximally Ca2+-activated in the isometric state and a approximately 3 degrees C, rapid ( 0.05 L0 s(-1), whereas the tension decreased to about < 0.5 x P0 during shortening at 0.1-0.2 L0 s(-1); the unloaded shortening velocity was approximately 1 L0 s(-1) and the curvature of the force-shortening velocity relation was high (a/P0 ratio from Hill's equation of approximately 0.05). In isometric state, a T-jump induced a tension rise of 15-20% to a new steady state; by curve fitting, the tension rise could be resolved into a fast (phase 2b, 40-50 s(-1)) and a slow (phase 3, 5-10 s(-1)) exponential component (as previously reported). During steady lengthening, a T-jump induced a small instantaneous drop in tension, followed by recovery, so that the final tension recorded with and without a T-jump was not significantly different; thus, a T-jump did not lead to a net increase of tension. During steady shortening, the T-jump induced a pronounced tension rise and both its amplitude and the rate (from a single exponential fit) increased with shortening velocity; at 0.1-0.2 L0 s(-1), the extent of fibre shortening during the T-jump tension rise was estimated to be approximately 1.2% L(0) and it was shorter at lower velocities. At a given shortening velocity and over the temperature range of 8-30 degrees C, the rate of T-jump tension rise increased with warming (Q10 approximately 2.7), similar to phase 2b (endothermic force generation) in isometric muscle. Results are discussed in relation to the previous findings in isometric muscle fibres which showed that a T-jump promotes an early step in the

  11. Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition.

    Science.gov (United States)

    Otto, William H; Coburn, Jared W; Brown, Lee E; Spiering, Barry A

    2012-05-01

    Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition. J Strength Cond Res 26(5): 1199-1202, 2012-The present study compared the effects of 6 weeks of weightlifting plus traditional heavy resistance training exercises vs. kettlebell training on strength, power, and anthropometric measures. Thirty healthy men were randomly assigned to 1 of 2 groups: (a) weightlifting (n = 13; mean ± SD: age, 22.92 ± 1.98 years; body mass, 80.57 ± 12.99 kg; height, 174.56 ± 5.80 cm) or (b) kettlebell (n = 17; mean ± SD: age, 22.76 ± 1.86 years; body mass, 78.99 ± 10.68 kg; height, 176.79 ± 5.08 cm) and trained 2 times a week for 6 weeks. A linear periodization model was used for training; at weeks 1-3 volume was 3 × 6 (kettlebell swings or high pull), 4 × 4 (accelerated swings or power clean), and 4 × 6 (goblet squats or back squats), respectively, and the volume increased during weeks 4-6 to 4 × 6, 6 × 4, and 4 × 6, respectively. Participants were assessed for height (in centimeters), body mass (in kilograms), and body composition (skinfolds). Strength was assessed by the back squat 1 repetition maximum (1RM), whereas power was assessed by the vertical jump and power clean 1RM. The results of this study indicated that short-term weightlifting and kettlebell training were effective in increasing strength and power. However, the gain in strength using weightlifting movements was greater than that during kettlebell training. Neither method of training led to significant changes in any of the anthropometric measures. In conclusion, 6 weeks of weightlifting induced significantly greater improvements in strength compared with kettlebell training. No between-group differences existed for the vertical jump or body composition.

  12. Short-term effects on lower-body functional power development: weightlifting vs. vertical jump training programs.

    Science.gov (United States)

    Tricoli, Valmor; Lamas, Leonardo; Carnevale, Roberto; Ugrinowitsch, Carlos

    2005-05-01

    Among sport conditioning coaches, there is considerable discussion regarding the efficiency of training methods that improve lower-body power. Heavy resistance training combined with vertical jump (VJ) training is a well-established training method; however, there is a lack of information about its combination with Olympic weightlifting (WL) exercises. Therefore, the purpose of this study was to compare the short-term effects of heavy resistance training combined with either the VJ or WL program. Thirty-two young men were assigned to 3 groups: WL = 12, VJ = 12, and control = 8. These 32 men participated in an 8-week training study. The WL training program consisted of 3 x 6RM high pull, 4 x 4RM power clean, and 4 x 4RM clean and jerk. The VJ training program consisted of 6 x 4 double-leg hurdle hops, 4 x 4 alternated single-leg hurdle hops, 4 x 4 single-leg hurdle hops, and 4 x 4 40-cm drop jumps. Additionally, both groups performed 4 x 6RM half-squat exercises. Training volume was increased after 4 weeks. Pretesting and posttesting consisted of squat jump (SJ) and countermovement jump (CMJ) tests, 10- and 30-m sprint speeds, an agility test, a half-squat 1RM, and a clean-and-jerk 1RM (only for WL). The WL program significantly increased the 10-m sprint speed (p strength more than the WL group (47.8 and 43.7%, respectively). Only the WL group improved in the SJ (9.5%). There were no significant changes in the control group. In conclusion, Olympic WL exercises seemed to produce broader performance improvements than VJ exercises in physically active subjects.

  13. Approximation and Calibration of Short-Term Implied Volatilities under Jump-Diffusion Stochastic Volatility

    OpenAIRE

    Alexey Medvedev; Olivier Scaillet

    2006-01-01

    We derive a closed-form asymptotic expansion formula for option implied volatility under a two-factor jump-diffusion stochastic volatility model when time-to-maturity is small. Based on numerical experiments we describe the range of time-to-maturity and moneyness for which the approximation is accurate. We further propose a simple calibration procedure of an arbitrary parametric model to short-term near-the-money implied volatilities. An important advantage of our approximation is that it is ...

  14. Effects of kettlebell training on postural coordination and jump performance

    DEFF Research Database (Denmark)

    Jay, Kenneth; Jakobsen, Markus Due; Sundstrup, Emil

    2013-01-01

    ABSTRACT: The aim of this study was to investigate the effectiveness of a worksite intervention using kettlebell training to improve postural reactions to perturbation and jump performance.This single-blind randomized controlled trial involved 40 adults (n=40) from occupations with a high...... prevalence of musculoskeletal pain and discomfort (mean age 44 years, body mass index 23 kg/m2, 85% women). A blinded examiner took measures at baseline and follow-up. Participants were randomly assigned to a training group - doing kettlebell swings three times a week for 8 weeks - or to a control group....... The outcome measures were postural reactions to sudden perturbation and maximal countermovement jump height.Compared to the control group, the training group significant decreased stopping time following perturbation (-109ms, 95% CI [-196:-21]). Jump height increased significantly in the training group (1.5cm...

  15. Birth-jump processes and application to forest fire spotting.

    Science.gov (United States)

    Hillen, T; Greese, B; Martin, J; de Vries, G

    2015-01-01

    Birth-jump models are designed to describe population models for which growth and spatial spread cannot be decoupled. A birth-jump model is a nonlinear integro-differential equation. We present two different derivations of this equation, one based on a random walk approach and the other based on a two-compartmental reaction-diffusion model. In the case that the redistribution kernels are highly concentrated, we show that the integro-differential equation can be approximated by a reaction-diffusion equation, in which the proliferation rate contributes to both the diffusion term and the reaction term. We completely solve the corresponding critical domain size problem and the minimal wave speed problem. Birth-jump models can be applied in many areas in mathematical biology. We highlight an application of our results in the context of forest fire spread through spotting. We show that spotting increases the invasion speed of a forest fire front.

  16. Nordic ski jumping injuries. A survey of active American jumpers.

    Science.gov (United States)

    Wright, J R; McIntyre, L; Rand, J J; Hixson, E G

    1991-01-01

    Little data are available in the medical literature on nordic ski jumping injuries. Injury questionnaires were sent to all active American ski jumpers registered either with the United States Ski Association or with a jumping club registered with the United States Ski Association. One hundred thirty-three of 286 (46.5%) injury questionnaires were returned. Eighty-one of the 133 respondents (60.9%) had been injured sufficiently to require examination by a physician at least once during their jumping careers. This report describes the types and frequencies of injuries sustained by this group of nordic ski jumpers as well as provides demographic data about American ski jumpers. The risk of injury per 100 participant years was 9.4, a rate less than that reported for most high school or college intermural sports.

  17. Basketball jump shooting is controlled online by vision.

    Science.gov (United States)

    de Oliveira, R Ferraz; Huys, R; Oudejans, R R D; van de Langenberg, R; Beek, P J

    2007-01-01

    An experiment was conducted to examine whether basketball jump shooting relies on online visual (i.e., dorsal stream-mediated) control rather than motor preprogramming. Seventeen expert basketball players (eight males and nine females) performed jump shots under normal vision and in three conditions in which movement initiation was delayed by zero, one, or two seconds relative to viewing the basket. Shots were evaluated in terms of both outcome and execution measures. Even though most shots still landed near the basket in the absence of vision, end-point accuracy was significantly better under normal visual conditions than under the delay conditions, where players tended to undershoot the basket. In addition, an overall decrease of inter-joint coordination strength and stability was found as a function of visual condition. Although these results do not exclude a role of motor preprogramming, they demonstrate that visual sensory information plays an important role in the continuous guidance of the basketball jump shot.

  18. Hydraulic jumps in a partially filled rotating cylinder

    International Nuclear Information System (INIS)

    Lundgren, T.S.; Berman, A.S.

    1979-06-01

    A nonlinear analysis is made of the fluid dynamics of a thin film of liquid completely spun up along the cylindrical wall of a rotating cylinder. The analysis allows for the possibility of hydraulic jumps in the liquid film. Conditions are simulated under which jumps can occur. Under the assumption that synchronous runouts are small relative to the film thickness, a sample calculation of jump position and extent for various operating frequencies is presented. Comparison with experimental observations indicate good qualitative agreement between the analysis and the experiment. Under the additional restriction of constant film thickness and a simple lumped-parameter dynamic model for the rotor and its supports, an analysis is also provided which predicts the amplitude and frequency of the asynchronous runout as a function of operating frequency. A numerical example of the results of such a calculation is provided. 6 figures

  19. Device for investigation of magnetic flux jumps in ribbon superconductors

    International Nuclear Information System (INIS)

    Andrianov, A.V.; Bashkirov, Yu.A.; Kremlev, M.G.

    1986-01-01

    A device for simulation of magnetic flux jumps in superconductors of conducting magnet sandwich-type windings super-applyed of a ribbon conductor is described. A superconducting magnet with a measuring cassetter are the main elements of the device. An external magnetic field is generated by a two-sectional superconducting magnet permitting to simulate the shape of the magnetic field characteristic for sandwich-type windings. Maximum radial component of the magnetic field is 2 T. Jumps of the magnetic flux are recorded by induction transducers and the magnetic field-by Hall trasducer. The effect of coating of standard metal on magnetic flux jumps in Nb 3 Sn base superconducting ribbon is considered

  20. A simple method for quantifying jump loads in volleyball athletes.

    Science.gov (United States)

    Charlton, Paula C; Kenneally-Dabrowski, Claire; Sheppard, Jeremy; Spratford, Wayne

    2017-03-01

    Evaluate the validity of a commercially available wearable device, the Vert, for measuring vertical displacement and jump count in volleyball athletes. Propose a potential method of quantifying external load during training and match play within this population. Validation study. The ability of the Vert device to measure vertical displacement in male, junior elite volleyball athletes was assessed against reference standard laboratory motion analysis. The ability of the Vert device to count jumps during training and match-play was assessed via comparison with retrospective video analysis to determine precision and recall. A method of quantifying external load, known as the load index (LdIx) algorithm was proposed using the product of the jump count and average kinetic energy. Correlation between two separate Vert devices and three-dimensional trajectory data were good to excellent for all jump types performed (r=0.83-0.97), with a mean bias of between 3.57-4.28cm. When matched against jumps identified through video analysis, the Vert demonstrated excellent precision (0.995-1.000) evidenced by a low number of false positives. The number of false negatives identified with the Vert was higher resulting in lower recall values (0.814-0.930). The Vert is a commercially available tool that has potential for measuring vertical displacement and jump count in elite junior volleyball athletes without the need for time-consuming analysis and bespoke software. Subsequently, allowing the collected data to better quantify load using the proposed algorithm (LdIx). Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  1. Suicides by jumping from a height in Hong Kong: a review of coroner court files.

    Science.gov (United States)

    Wong, Paul W C; Caine, Eric D; Lee, Carmen K M; Beautrais, Annette; Yip, Paul S F

    2014-02-01

    Jumping from a height is the most common method for suicide in Hong Kong and other urban cities, but it remains understudied locally and internationally. We used Coroner records in exploring the ecological factors associated with these deaths and the personal characteristics of persons who jumped to their death (hereafter, "jumping suicides"). We compared suicides by jumping with all other suicides and examined the suicides that occurred at ten different jumping sites. The Coroner's files of all suicides in Hong Kong from 2002 to 2007 included 6,125 documented deaths. 2,964 (48.4%) involved jumping during the study period. Eighty-three percent (83%) of suicide jumps occurred in residential buildings, and of these, 61% occurred from the decedent's own home. Jumping suicides differed from non-jumping suicides in terms of their socio-demographic characteristics (e.g., for male: 60.8 vs. 67.3% of jumping suicide and non-jumping suicides, p suicides, p suicides (p suicide prevention. Installation of physical barriers, one of the mean restriction strategies, at common places for suicide has strong evidence to avert suicides without substitution effects. There seems to be challenges to implement physical barriers to prevent residential jumping suicides. Simply applying physical barriers to preclude jumping in Hong Kong appears to be difficult given its ubiquitous "high-rise" residential dwellings. Hence, we also need to develop alternative strategies aimed at preventing people from becoming suicidal.

  2. Does gymnastics practice improve vertical jump reliability from the age of 8 to 10 years?

    Science.gov (United States)

    Marina, Michel; Torrado, Priscila

    2013-01-01

    The objective of this study was to confirm whether gymnastics practice from a young age can induce greater vertical jump reliability. Fifty young female gymnasts (8.84 ± 0.62 years) and 42 females in the control group (8.58 ± 0.92 years) performed the following jump tests on a contact mat: squat jump, countermovement jump, countermovement jump with arm swing and drop jump from heights of 40 and 60 cm. The two testing sessions had three trials each and were separated by one week. A 2 (groups) × 2 (sessions) × 3 (trials) repeated measures analysis of variance (ANOVA) and a test-retest correlation analysis were used to study the reliability. There was no systematic source of error in either group for non-plyometric jumps such as squat jump, countermovement jump, and countermovement jump with arm swing. A significant group per trial interaction revealed a learning effect in gymnasts' drop jumps from 40 cm height. Additionally, the test-retest correlation analysis and the higher minimum detectable error suggest that the quick drop jump technique was not fully consolidated in either group. At an introductory level of gymnastics and between the ages of 8-10 years, the condition of being a gymnast did not lead to conclusively higher reliability, aside from better overall vertical jump performance.

  3. Validation of an inertial measurement unit for the measurement of jump count and height.

    Science.gov (United States)

    MacDonald, Kerry; Bahr, Roald; Baltich, Jennifer; Whittaker, Jackie L; Meeuwisse, Willem H

    2017-05-01

    To validate the use of an inertial measurement unit (IMU) for the collection of total jump count and assess the validity of an IMU for the measurement of jump height against 3-D motion analysis. Cross sectional validation study. 3D motion-capture laboratory and field based settings. Thirteen elite adolescent volleyball players. Participants performed structured drills, played a 4 set volleyball match and performed twelve counter movement jumps. Jump counts from structured drills and match play were validated against visual count from recorded video. Jump height during the counter movement jumps was validated against concurrent 3-D motion-capture data. The IMU device captured more total jumps (1032) than visual inspection (977) during match play. During structured practice, device jump count sensitivity was strong (96.8%) while specificity was perfect (100%). The IMU underestimated jump height compared to 3D motion-capture with mean differences for maximal and submaximal jumps of 2.5 cm (95%CI: 1.3 to 3.8) and 4.1 cm (3.1-5.1), respectively. The IMU offers a valid measuring tool for jump count. Although the IMU underestimates maximal and submaximal jump height, our findings demonstrate its practical utility for field-based measurement of jump load. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Jump Testing and the Speed of Market Adjustment

    DEFF Research Database (Denmark)

    Rasmussen, Torben B.

    Asymptotic properties of jump tests rely on the property that any jump occurs within a single time interval no matter what the observation frequency is. Market microstructure effects in relation to news-induced revaluation of the underlying variable is likely to make this an unrealistic assumption...... is investigated here and in a simulation study. Evidence indicates that tests based on the largest of scaled price increments perform better than tests comparing measures of variability. Resolving the matter by testing at lower frequencies turns out to be less straightforward....

  5. Pricing Participating Products under a Generalized Jump-Diffusion Model

    Directory of Open Access Journals (Sweden)

    Tak Kuen Siu

    2008-01-01

    Full Text Available We propose a model for valuing participating life insurance products under a generalized jump-diffusion model with a Markov-switching compensator. It also nests a number of important and popular models in finance, including the classes of jump-diffusion models and Markovian regime-switching models. The Esscher transform is employed to determine an equivalent martingale measure. Simulation experiments are conducted to illustrate the practical implementation of the model and to highlight some features that can be obtained from our model.

  6. Increased Distance of Shooting on Basketball Jump Shot

    OpenAIRE

    Okazaki, Victor Hugo Alves; Rodacki, André Luiz Félix

    2012-01-01

    The present study analyzed the effect of increased distance on basketball jump shot outcome and performance. Ten male expert basketball players were filmed and a number of kinematic variables analyzed during jump shot that were performed from three conditions to represent close, intermediate and far distances (2.8, 4.6, and 6.4m, respectively). Shot accuracy decreased from 59% (close) to 37% (far), in function of the task constraints (p < 0.05). Ball release height decreased (p < 0.05) from 2...

  7. Probabilistic dynamics of some jump-diffusion systems.

    Science.gov (United States)

    Daly, Edoardo; Porporato, Amilcare

    2006-02-01

    Some exact solutions to the forward Chapman-Kolmogorov equation are derived for processes driven by both Gaussian and compound Poisson (shot) noise. The combined action of these two forms of white noise is analyzed in transient and equilibrium conditions for different jump distributions and additive Gaussian noise. Steady-state distributions with power-law tails are obtained for exponentially distributed jumps and multiplicative linear Gaussian noise. Two applications are discussed: namely, the virtual waiting-time or Takàcs process including Gaussian oscillations and a simplified model of soil moisture dynamics, in which rainfall is modeled as a compound Poisson process and fluctuations in potential evapotranspiration are Gaussian.

  8. Two bi-stability jumps in theoretical wind models for massive stars and the implications for luminous blue variable supernovae

    Science.gov (United States)

    Petrov, Blagovest; Vink, Jorick S.; Gräfener, Götz

    2016-05-01

    Luminous blue variables (LBVs) have been suggested to be the direct progenitors of supernova Types IIb and IIn, with enhanced mass loss prior to explosion. However, the mechanism of this mass loss is not yet known. Here, we investigate the qualitative behaviour of theoretical stellar wind mass loss as a function of Teff across two bi-stability jumps in blue supergiant regime and also in proximity to the Eddington limit, relevant for LBVs. To investigate the physical ingredients that play a role in the radiative acceleration we calculate blue supergiant wind models with the CMFGEN non-local thermodynamic equilibrium model atmosphere code over an effective temperature range between 30 000 and 8800 K. Although our aim is not to provide new mass-loss rates for BA supergiants, we study and confirm the existence of two bi-stability jumps in mass-loss rates predicted by Vink et al. However, they are found to occur at somewhat lower Teff (20 000 and 9000 K, respectively) than found previously, which would imply that stars may evolve towards lower Teff before strong mass loss is induced by the bi-stability jumps. When the combined effects of the second bi-stability jump and the proximity to Eddington limit are accounted for, we find a dramatic increase in the mass-loss rate by up to a factor of 30. Further investigation of both bi-stability jumps is expected to lead to a better understanding of discrepancies between empirical modelling and theoretical mass-loss rates reported in the literature, and to provide key inputs for the evolution of both normal AB supergiants and LBVs, as well as their subsequent supernova Type II explosions.

  9. Who jumps the highest? Anthropometric and physiological correlations of vertical jump in youth elite female volleyball players.

    Science.gov (United States)

    Nikolaidis, Pantelis T; Gkoudas, Konstantinos; Afonso, José; Clemente-Suarez, Vicente J; Knechtle, Beat; Kasabalis, Stavros; Kasabalis, Athanasios; Douda, Helen; Tokmakidis, Savvas; Torres-Luque, Gema

    2017-06-01

    The aim of the present study was to examine the relationship of vertical jump (Abalakov jump [AJ]) with anthropometric and physiological parameters in youth elite female volleyball players. Seventy-two selected volleyball players from the region of Athens (age 13.3±0.7 years, body mass 62.0±7.2 kg, height 171.5±5.7 cm, body fat 21.2±4.5%), classified into quartiles according to AJ performance (group A, 21.4-26.5 cm; group B, 26.8-29.9 cm; group C, 30.5-33.7 cm; group D, 33.8-45.9 cm), performed a series of physical fitness tests. AJ was correlated with anthropometric (age at peak height velocity [APHV]: r=0.38, Pvolleyball players that jumped the highest were those who matured later than others.

  10. Improved delay-dependent globally asymptotic stability of delayed uncertain recurrent neural networks with Markovian jumping parameters

    International Nuclear Information System (INIS)

    Yan, Ji; Bao-Tong, Cui

    2010-01-01

    In this paper, we have improved delay-dependent stability criteria for recurrent neural networks with a delay varying over a range and Markovian jumping parameters. The criteria improve over some previous ones in that they have fewer matrix variables yet less conservatism. In addition, a numerical example is provided to illustrate the applicability of the result using the linear matrix inequality toolbox in MATLAB. (general)

  11. Improved delay-dependent globally asymptotic stability of delayed uncertain recurrent neural networks with Markovian jumping parameters

    Science.gov (United States)

    Ji, Yan; Cui, Bao-Tong

    2010-06-01

    In this paper, we have improved delay-dependent stability criteria for recurrent neural networks with a delay varying over a range and Markovian jumping parameters. The criteria improve over some previous ones in that they have fewer matrix variables yet less conservatism. In addition, a numerical example is provided to illustrate the applicability of the result using the linear matrix inequality toolbox in MATLAB.

  12. Toxicity and population structure of the Rough?Skinned Newt (Taricha granulosa) outside the range of an arms race with resistant predators

    OpenAIRE

    Hague, Michael T.J.; Avila, Lele?a A.; Hanifin, Charles T.; Snedden, W. Andrew; Stokes, Amber N.; Brodie, Edmund D.; Brodie, Edmund D.

    2016-01-01

    Abstract Species interactions, and their fitness consequences, vary across the geographic range of a coevolutionary relationship. This spatial heterogeneity in reciprocal selection is predicted to generate a geographic mosaic of local adaptation, wherein coevolutionary traits are phenotypically variable from one location to the next. Under this framework, allopatric populations should lack variation in coevolutionary traits due to the absence of reciprocal selection. We examine phenotypic var...

  13. The prevalence of ski jumping among pupils in the first triad of primary school

    OpenAIRE

    Vtič, Maja

    2016-01-01

    As one of the most widespread sports discipline in Slovenia, ski jumping has a long tradition. Ski jumping is a competitive sport at which recreational engagement is not possible because of its special features and specifics. It is one of the basic sports activities for the development of children's motor skills, since ski jumping requires an integrated training of the trainee. Ski jumping is basically a winter sport, whereas in the summer season, it has also become increasingly present with ...

  14. Variability of Jump Kinetics Related to Training Load in Elite Female Basketball

    OpenAIRE

    Jan Legg; David B. Pyne; Stuart Semple; Nick Ball

    2017-01-01

    The purpose of this study was to quantify changes in jump performance and variability in elite female basketballers. Junior and senior female representative basketball players (n = 10) aged 18 ± 2 years participated in this study. Countermovement jump (CMJ) data was collected with a Gymaware™ optical encoder at pre-, mid-, and post-season time points across 10 weeks. Jump performance was maintained across the course of the full season (from pre to post). Concentric peak velocity, jump height,...

  15. Delayed Frost Growth on Jumping-Drop Superhydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Boreyko, Jonathan B [ORNL; Collier, Pat [ORNL

    2013-01-01

    Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an inter-drop frost wave. The growth of this inter-drop frost front is shown to be up to three times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of inter-drop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an inter-drop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser was found to be superior to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by minimizing the success of interdrop ice bridge formation.

  16. Mechanical output in jumps of marmosets (Callithrix jacchus).

    Science.gov (United States)

    Bobbert, Maarten F; Plas, Rogier L C; Weide, Guido; Clairbois, H E Bert; Hofman, Sam O; Jaspers, Richard T; Philippens, Ingrid H C H M

    2014-02-15

    In this study we determined the mechanical output of common marmosets (Callithrix jacchus) during jumping. Vertical ground reaction forces were measured in 18 animals while they jumped from an instrumented crossbar to a crossbar located 70 cm higher. From the vertical force time histories, we calculated the rate of change of mechanical energy of the centre of mass (dE/dt). The mean value of dE/dt during the push-off amounted to 51.8±6.2 W kg(-1) body mass, and the peak value to 116.4±17.6 W kg(-1) body mass. We used these values in combination with masses of leg muscles, determined in two specimens, to estimate mean and peak values of dE/dt of 430 and 970 W kg(-1) muscle, respectively. These values are higher than values reported in the literature for jumps of humans and bonobos, but smaller than those of jumps of bushbabies. Surprisingly, the mean value of dE/dt of 430 W kg(-1) muscle was close to the maximal power output of 516 W kg(-1) muscle reported in the literature for isokinetic contractions of rat medial gastrocnemius, one of the fastest mammalian muscles. Further study of the force-velocity relationship of muscle tissue of small primates is indicated.

  17. A jump persistent turning walker to model zebrafish locomotion.

    Science.gov (United States)

    Mwaffo, Violet; Anderson, Ross P; Butail, Sachit; Porfiri, Maurizio

    2015-01-06

    Zebrafish are gaining momentum as a laboratory animal species for the investigation of several functional and dysfunctional biological processes. Mathematical models of zebrafish behaviour are expected to considerably aid in the design of hypothesis-driven studies by enabling preliminary in silico tests that can be used to infer possible experimental outcomes without the use of zebrafish. This study is motivated by observations of sudden, drastic changes in zebrafish locomotion in the form of large deviations in turn rate. We demonstrate that such deviations can be captured through a stochastic mean reverting jump diffusion model, a process that is commonly used in financial engineering to describe large changes in the price of an asset. The jump process-based model is validated on trajectory data of adult subjects swimming in a shallow circular tank obtained from an overhead camera. Through statistical comparison of the empirical distribution of the turn rate against theoretical predictions, we demonstrate the feasibility of describing zebrafish as a jump persistent turning walker. The critical role of the jump term is assessed through comparison with a simplified mean reversion diffusion model, which does not allow for describing the heavy-tailed distributions observed in the fish turn rate. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  18. Spatiotemporal characteristics of motor actions by blind long jump athletes.

    Science.gov (United States)

    Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

    2017-01-01

    Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board.

  19. Jump tests for semimartingales | Hong | South African Actuarial ...

    African Journals Online (AJOL)

    This paper aims to introduce jump tests to the actuarial community. In actuarial science, semimartingales are extensively used in the models for interest rates, options, variable annuities and equity-linked annuities. Those models usually assume without justification that the underlying asset process follows a continuous ...

  20. Numerical simulation of toner jumping method for nonimpact printing

    Science.gov (United States)

    Kutsuwada, Noboru; Shohdohji, Tsutomu; Izawa, Harunobu; Okada, Nobuhiro; Sugai, Takashi

    1993-06-01

    The `toner jumping method' is proposed to more simply conduct the non-impact printing process in electrophotography. To clarify the fundamental functions of this method, in this paper, the jumping behavior of toner is studied by simulating with the aid of a personal computer. To control the locus and distribution of toner from a magnet roller electrode to the paper on the back electrode, the mesh electrode is assumed to be inserted at the middle of the roller and back electrode. Between the magnet roller electrode and the back electrode the higher dc voltage is applied compared with the mesh electrode against the roller electrode. The locus and distribution of toner reaching the paper are simulated changing the applied voltage in each raw's and column's direction of mesh electrode. It is assumed to be possible to control the jumping behavior of toner from magnet roller to paper. As a result, the role of the mesh electrode in the `toner jumping method' on the quality of image in the non-impact printing process is suggested.

  1. Environmentally transmitted parasites: Host-jumping in a heterogeneous environment.

    Science.gov (United States)

    Caraco, Thomas; Cizauskas, Carrie A; Wang, Ing-Nang

    2016-05-21

    Groups of chronically infected reservoir-hosts contaminate resource patches by shedding a parasite׳s free-living stage. Novel-host groups visit the same patches, where they are exposed to infection. We treat arrival at patches, levels of parasite deposition, and infection of the novel host as stochastic processes, and derive the expected time elapsing until a host-jump (initial infection of a novel host) occurs. At stationarity, mean parasite densities are independent of reservoir-host group size. But within-patch parasite-density variances increase with reservoir group size. The probability of infecting a novel host declines with parasite-density variance; consequently larger reservoir groups extend the mean waiting time for host-jumping. Larger novel-host groups increase the probability of a host-jump during any single patch visit, but also reduce the total number of visits per unit time. Interaction of these effects implies that the waiting time for the first infection increases with the novel-host group size. If the reservoir-host uses resource patches in any non-uniform manner, reduced spatial overlap between host species increases the waiting time for host-jumping. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. The fluid dynamics of swimming by jumping in copepods

    DEFF Research Database (Denmark)

    Jiang, Houshuo; Kiørboe, Thomas

    2011-01-01

    Copepods swim either continuously by vibrating their feeding appendages or erratically by repeatedly beating their swimming legs resulting in a series of small jumps. The two swimming modes generate different hydrodynamic disturbances and therefore expose the swimmers differently to rheotactic pr...

  3. Some model problems of the dynamics of a jumping vehicle

    Science.gov (United States)

    Beletskii, V. V.; Dolganov, A. V.; Salimova, O. P.

    1992-06-01

    The paper considers two model problems of a vehicle moving on the surface of a planetoid by jumping. The vehicle is represented by a physical point subject to attraction from gravitational fields of different types. A characteristic feature of this problem is the effect on the vehicle of the planetoid-surface impacts, resulting in a complex, 'multipetaled', trajectory.

  4. Contribution to the experimental study of the hydraulic jump in ...

    African Journals Online (AJOL)

    The purpose of this study is to study experimentally the hydraulic jump evolving in a symmetric trapezoidal channel with a positive slope, requires the use of an experimental protocol, and to find experimental relations linking the characteristics of the formed projection. The experimental study investigated the variation of the ...

  5. Trading price jump clusters in foreign exchange markets

    Czech Academy of Sciences Publication Activity Database

    Novotný, Jan; Petrov, D.; Urga, G.

    2015-01-01

    Roč. 24, June (2015), s. 66-92 ISSN 1386-4181 R&D Projects: GA ČR(CZ) GA14-27047S Institutional support: RVO:67985998 Keywords : price jumps * foreign exchange markets * trading Subject RIV: AH - Economics Impact factor: 1.726, year: 2015

  6. Barbara McClintock and the Discovery of Jumping Genes

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE. Barbara McClintock and the Discovery of Jumping Genes. Vidyanand Nanjundiah works in the. Developmental Biology and Genetics Laboratory at the Indian Institute of. Science. After a Master's degree in physics he took up biology. He is interested in evolutionary biology and pattern formation during.

  7. The Missing Luminous Blue Variables and the Bistability Jump

    NARCIS (Netherlands)

    Smith, N.; Vink, J.S.; de Koter, A.

    2004-01-01

    We discuss an interesting feature of the distribution of luminous blue variables (LBVs) on the H-R diagram, and we propose a connection with the bistability jump seen in the winds of early-type supergiants. There appears to be a deficiency of quiescent LBVs on the S Doradus instability strip at

  8. Spatiotemporal characteristics of motor actions by blind long jump athletes

    Science.gov (United States)

    Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

    2017-01-01

    Background Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. Objective The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. Methods We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. Results The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. Conclusion The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board. PMID:29018542

  9. Influence of Competition on Vertical Jump, Kicking Speed, Sprint ...

    African Journals Online (AJOL)

    The objective of this study was to analyse the influence of competition level (elite group [EG] and sub-elite group [SG]), on the Counter Movement Jump (CMJ), Kicking Speed (KS), sprint and agility in young football players. The subjects were 79 young football players (14 to 18 years old), from Andalusian football teams with ...

  10. Estimation and prediction under local volatility jump-diffusion model

    Science.gov (United States)

    Kim, Namhyoung; Lee, Younhee

    2018-02-01

    Volatility is an important factor in operating a company and managing risk. In the portfolio optimization and risk hedging using the option, the value of the option is evaluated using the volatility model. Various attempts have been made to predict option value. Recent studies have shown that stochastic volatility models and jump-diffusion models reflect stock price movements accurately. However, these models have practical limitations. Combining them with the local volatility model, which is widely used among practitioners, may lead to better performance. In this study, we propose a more effective and efficient method of estimating option prices by combining the local volatility model with the jump-diffusion model and apply it using both artificial and actual market data to evaluate its performance. The calibration process for estimating the jump parameters and local volatility surfaces is divided into three stages. We apply the local volatility model, stochastic volatility model, and local volatility jump-diffusion model estimated by the proposed method to KOSPI 200 index option pricing. The proposed method displays good estimation and prediction performance.

  11. RunJumpCode: An Educational Game for Educating Programming

    Science.gov (United States)

    Hinds, Matthew; Baghaei, Nilufar; Ragon, Pedrito; Lambert, Jonathon; Rajakaruna, Tharindu; Houghton, Travers; Dacey, Simon

    2017-01-01

    Programming promotes critical thinking, problem solving and analytic skills through creating solutions that can solve everyday problems. However, learning programming can be a daunting experience for a lot of students. "RunJumpCode" is an educational 2D platformer video game, designed and developed in Unity, to teach players the…

  12. Kinetics analysis of step and jump forward lunge among badminton ...

    African Journals Online (AJOL)

    This study was conducted to determine and compare the kinetics during step forward lunge (SFL) and jump forward lunge (JFL) in badminton. Fifteen university badminton players (mean age = 22.07 ± 1.39 years old) were recruited and were assigned to perform SFL and JFL while holding a badminton racquet using their ...

  13. The Jump Training Program. In Season Conditioning for Women's Basketball.

    Science.gov (United States)

    Hannam, Sue; And Others

    1988-01-01

    Women athletes have been successful in maintaining and/or increasing their conditioning and vertical jump levels when they participate in the in-season circuit training program described in this article. An exercise guide, sample individual score card, and photos of women practicing the exercises are included. (IAH)

  14. Security Sensor System Based on Large Barkhausen Jump of ...

    African Journals Online (AJOL)

    This paper presents and discusses preliminary laboratory results for fabrication and testing of a security sensor system for use in article surveillance in such places as libraries, CD rental shops, and supermarkets, as a crime preventive measure. The system employs the large Barkhausen jump (LBJ) inherent in the ...

  15. The Jumping Ring and Lenz's Law--An Analysis

    Science.gov (United States)

    Bostock-Smith, J. M.

    2008-01-01

    Lenz's law is sometimes invoked to explain the behaviour of the jumping, or levitating, ring. This is shown to be incomplete, and an alternative explanation using Faraday's laws and circuit analysis is offered. This leads to the choice of optimum material and dimensions for the ring. (Contains 1 table and 4 figures.)

  16. Study of the semi-theoretical relation of the hydraulic jump evolving ...

    African Journals Online (AJOL)

    This study has for objective to study the theoretical relation of the hydraulic jump by sill, evolving in an U-shaped channel, with a rough bed. Functional relations, in non-dimensional form, relating the jump characteristics, seeming the effect of the bed's roughness, are obtained. A comparative study with the hydraulic jump in ...

  17. Neuromuscular adaptations to 4 weeks of intensive drop jump training in well-trained athletes

    DEFF Research Database (Denmark)

    Alkjær, Tine; Meyland, Jacob; Raffalt, Peter C

    2013-01-01

    This study examined the effects of 4 weeks of intensive drop jump training in well-trained athletes on jumping performance and underlying changes in biomechanics and neuromuscular adaptations. Nine well-trained athletes at high national competition level within sprinting and jumping disciplines...

  18. Movement Analysis Applied to the Basketball Jump Shot--Part II.

    Science.gov (United States)

    Martin, Thomas P.

    1981-01-01

    The jump shot is one of the most important shots in the game of basketball. The movement analysis of the jump shot designates four phases: (1) preparatory position; (2) movement phase I (crouch); (3) movement phase II (jump); and (4) follow-through. (JN)

  19. Is the effect of a countermovement on jump height due to active state development?

    NARCIS (Netherlands)

    Bobbert, M.F.; Casius, L.J.R.

    2005-01-01

    Purpose: To investigate whether the difference in jump height between countermovement jumps (CMJ) and squat jumps (SJ) could be explained by a difference in active state during propulsion. Methods: Simulations were performed with a model of the human musculoskeletal system comprising four body

  20. Gender bias in jumping kinetics in National Collegiate Athletic Association Division I basketball players.

    Science.gov (United States)

    Walsh, Mark S; Waters, Jeff A; Böhm, Harald; Potteiger, Jeff A

    2007-08-01

    The purposes of this study are to examine gender differences in the contribution of the arm swing to jump height in men and women basketball players and to examine the role of upper-body strength in the contribution of arm swing to jump height. National Collegiate Athletic Association Division I basketball players (men n = 13, women n = 12) performed 4 jumping movements: squat jumps with hands on hips (SNA) and with arm swings (SA) and countermovement jumps with hands on hips and with arm swings (CMA). Differences were found between the jump heights of men and women. Use of the arms increased the jump height of men more than women. Compared with the SNA, the SA allowed an increase of 7 cm (23%) for men and 4 cm (17%) for women. The CMA allowed for an increase of 10 cm (30%) for men and 6 cm (24%) for women. General upper-body strength measures did not correlate strongly with the effect of arms on jumping, but peak power did. As in previous studies, peak power had a high correlation with jumping performance. These results show that the arm swing contributes significantly to jump performance in both men and women basketball players and that strength training for jumping should focus on power production and lifting exercises that are jump specific.

  1. Effect of a neuromuscular training program on the kinetics and kinematics of jumping tasks.

    Science.gov (United States)

    Chappell, Jonathan D; Limpisvasti, Orr

    2008-06-01

    Altered motor control strategies are a proposed cause of the female athlete's increased risk for noncontact anterior cruciate ligament injury. Injury prevention programs have shown promising results in decreasing the incidence of anterior cruciate ligament injury. To evaluate the effect of the Kerlan-Jobe Orthopaedic Clinic Modified Neuromuscular Training Program on the biomechanics of select jumping tasks in the female collegiate athlete. Controlled laboratory study. Thirty female National Collegiate Athletic Association Division I soccer and basketball players performed vertical jump, hopping tests, and 2 jumping tasks (drop jump and stop jump). All subjects completed a 6-week neuromuscular training program with core strengthening and plyometric training. Three-dimensional motion analysis and force plate data were used to compare the kinetics and kinematics of jumping tasks before and after training. Dynamic knee valgus moment during the stance phase of stop jump tasks decreased after completion of the neuromuscular training program (P = .04), but differences were not observed for the drop jump. Initial knee flexion (P = .003) and maximum knee flexion (P = .006) angles increased during the stance phase of drop jumps after training, but differences were not observed for the stop jump. The athletes showed improved performance in vertical jump (P training program improved select athletic performance measures and changed movement patterns during jumping tasks in the subject population. The use of this neuromuscular training program could potentially modify the collegiate athlete's motion strategies, improve performance, and lower the athlete's risk for injury.

  2. Muscle activation history at different vertical jumps and its influence on vertical velocity

    NARCIS (Netherlands)

    Kopper, Bence; Csende, Zsolt; Safar, Sandor; Hortobagyi, Tibor; Tihanyi, Jozsef

    In the present study we investigated displacement, time, velocity and acceleration history of center of mass (COM) and electrical activity of knee extensors to estimate the dominance of the factors influencing the vertical velocity in squat jumps (SJs), countermovement jumps (CMJs) and drop jumps

  3. Is energy expenditure taken into account in human sub-maximal jumping? - a simulation study

    NARCIS (Netherlands)

    Vanrenterghem, J.; Bobbert, M.F.; Casius, L.J.R.; de Clercq, D.

    2008-01-01

    This paper presents a simulation study that was conducted to investigate whether the stereotyped motion pattern observed in human sub-maximal jumping can be interpreted from the perspective of energy expenditure. Human sub-maximal vertical countermovement jumps were compared to jumps simulated with

  4. Estimation of Joint Forces and Moments for the In-Run and Take-Off in Ski Jumping Based on Measurements with Wearable Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Grega Logar

    2015-05-01

    Full Text Available This study uses inertial sensors to measure ski jumper kinematics and joint dynamics, which was until now only a part of simulation studies. For subsequent calculation of dynamics in the joints, a link-segment model was developed. The model relies on the recursive Newton–Euler inverse dynamics. This approach allowed the calculation of the ground reaction force at take-off. For the model validation, four ski jumpers from the National Nordic center performed a simulated jump in a laboratory environment on a force platform; in total, 20 jumps were recorded. The results fit well to the reference system, presenting small errors in the mean and standard deviation and small root-mean-square errors. The error is under 12% of the reference value. For field tests, six jumpers participated in the study; in total, 28 jumps were recorded. All of the measured forces and moments were within the range of prior simulated studies. The proposed system was able to indirectly provide the values of forces and moments in the joints of the ski-jumpers’ body segments, as well as the ground reaction force during the in-run and take-off phases in comparison to the force platform installed on the table. Kinematics assessment and estimation of dynamics parameters can be applied to jumps from any ski jumping hill.

  5. Estimation of joint forces and moments for the in-run and take-off in ski jumping based on measurements with wearable inertial sensors.

    Science.gov (United States)

    Logar, Grega; Munih, Marko

    2015-05-13

    This study uses inertial sensors to measure ski jumper kinematics and joint dynamics, which was until now only a part of simulation studies. For subsequent calculation of dynamics in the joints, a link-segment model was developed. The model relies on the recursive Newton-Euler inverse dynamics. This approach allowed the calculation of the ground reaction force at take-off. For the model validation, four ski jumpers from the National Nordic center performed a simulated jump in a laboratory environment on a force platform; in total, 20 jumps were recorded. The results fit well to the reference system, presenting small errors in the mean and standard deviation and small root-mean-square errors. The error is under 12% of the reference value. For field tests, six jumpers participated in the study; in total, 28 jumps were recorded. All of the measured forces and moments were within the range of prior simulated studies. The proposed system was able to indirectly provide the values of forces and moments in the joints of the ski-jumpers' body segments, as well as the ground reaction force during the in-run and take-off phases in comparison to the force platform installed on the table. Kinematics assessment and estimation of dynamics parameters can be applied to jumps from any ski jumping hill.

  6. Jumping for recognition: Women's ski jumping viewed as a struggle for rights.

    Science.gov (United States)

    Andersen, W; Loland, S

    2017-03-01

    With the campaign for women's participation in international and Olympic ski jumping as a practical case, sport's potential for recognition of individual rights is explored. In line with Honneth's influential ethical theory, recognition of rights refers to a mutual recognition between persons of each other as rational and responsible agents with an equal right to take part in the public formation and development of their community or practice. The argument is that women ski jumpers were entitled to compete as they had actual and/or potential capabilities and skills to contribute in the public formation and development of their sport. Their exclusion was a violation of individual rights. At a more general level, sport is discussed as a sphere for recognition of rights. It is argued that the basic principles of equal opportunity to take part and to perform make sport a particularly clear and potent sphere for such recognition, and also for the identification of rights violations. In sport, rights, or the violation of rights, are demonstrated in concrete and embodied ways. It is concluded that struggles for recognition and individual rights are a continuous process in sport as in most other human institutions and practices. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. ELEMENTS OF KINEMATICS SPECIFIC TO THE JUMP OF THE MALE TRIPLE JUMP EVENT

    Directory of Open Access Journals (Sweden)

    MIHAI ILIE

    2010-12-01

    Full Text Available The quality of results obtained in competitions is based on the use of the most efficient technologies and conducting systems in the sportive training process, all embedded in operational strategies to enable the efficient filtering of the information exchange between coaches and athletes in order to ensure all the resources needed for an optimal monitoring and conveyance training process. The purpose of this study was to examine the kinematic point of view the main technical aspects of specific proof of triple last step - the long jump. Research was conducted on athletes who specialize in thissample, and components of the National Olympic Lot Romanian Athletics Federation. Using kinematic analysis software movement - Dartfish © I obtained a series of kinematic parameters (time, position, angles discussed specific issues in research, processing and interpretation leading to the general conclusion according to which: kinematic analysis of the key features approach specific technical triple last step of the sample by use of IT leads to useful information specific to this test in monitoring technique

  8. The relationship between kinematic determinants of jump and sprint performance in division I women soccer players.

    Science.gov (United States)

    McCurdy, Kevin W; Walker, John L; Langford, George A; Kutz, Matt R; Guerrero, James M; McMillan, Jeremy

    2010-12-01

    The purpose of this study was to determine the relationship between measures of unilateral and bilateral jumping performance and 10- and 25-m sprint performance. Fifteen division I women soccer players (height 165 ± 2.44 cm, mass 61.65 ± 7.7 kg, age 20.19 ± 0.91 years) volunteered to participate in this study. The subjects completed a 10- and 25-m sprint test. The following jump kinematic variables were measured using accelerometry: sprint time, step length, step frequency, jump height and distance, contact time, concentric contact time, and flight time (Inform Sport Training Systems, Victoria, BC, Canada). The following jumps were completed in random order: bilateral countermovement vertical jump, bilateral countermovement horizontal jump, bilateral 40-cm drop vertical jump, bilateral 40-cm drop horizontal jump, unilateral countermovement vertical jump (UCV), unilateral countermovement horizontal jump, unilateral 20-cm drop vertical jump (UDV), and unilateral 20-cm drop horizontal jump (UDH). The trial with the best jump height or distance, reactive strength (jump height or distance/total contact time), and flight time to concentric contact time ratio (FT/CCT) was recorded to analyze the relationship between jump kinematics and sprint performance. None of the bilateral jump kinematics significantly correlated with 10- and 25-m sprint time, step length, or step frequency. Right-leg jump height (r = -0.71, p = 0.006, SEE = 0.152 seconds), FT/CCT (r = -0.58, p = 0.04, SEE = 0.176 seconds), and combined right and left-leg jump height (r = -0.61) were significantly correlated with the 25-m sprint time during the UCV. Right-leg FT/CCT was also significantly related to 25-m step length (r = 0.68, p = 0.03, SEE = 0.06 m) during the UDV. The combined right and left leg jump distance to standing height ratio during the UDH significantly correlated (r = -0.58) with 10-m sprint time. In comparison to bilateral jumps, unilateral jumps produced a stronger relationship with

  9. The kinematics of swimming and relocation jumps in copepod nauplii.

    Directory of Open Access Journals (Sweden)

    Christian Marc Andersen Borg

    Full Text Available Copepod nauplii move in a world dominated by viscosity. Their swimming-by-jumping propulsion mode, with alternating power and recovery strokes of three pairs of cephalic appendages, is fundamentally different from the way other microplankters move. Protozoans move using cilia or flagella, and copepodites are equipped with highly specialized swimming legs. In some species the nauplius may also propel itself more slowly through the water by beating and rotating the appendages in a different, more complex pattern. We use high-speed video to describe jumping and swimming in nauplii of three species of pelagic copepods: Temora longicornis, Oithona davisae and Acartia tonsa. The kinematics of jumping is similar between the three species. Jumps result in a very erratic translation with no phase of passive coasting and the nauplii move backwards during recovery strokes. This is due to poorly synchronized recovery strokes and a low beat frequency relative to the coasting time scale. For the same reason, the propulsion efficiency of the nauplii is low. Given the universality of the nauplius body plan, it is surprising that they seem to be inefficient when jumping, which is different from the very efficient larger copepodites. A slow-swimming mode is only displayed by T. longicornis. In this mode, beating of the appendages results in the creation of a strong feeding current that is about 10 times faster than the average translation speed of the nauplius. The nauplius is thus essentially hovering when feeding, which results in a higher feeding efficiency than that of a nauplius cruising through the water.

  10. Jumping-droplet electronics hot-spot cooling

    International Nuclear Information System (INIS)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle

    2017-01-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm 2 ). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm 2 . Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  11. Jumping-droplet electronics hot-spot cooling

    Science.gov (United States)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

    2017-03-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  12. The effects of barbell load on countermovement vertical jump power and net impulse.

    Science.gov (United States)

    Mundy, Peter D; Smith, Neal A; Lauder, Mike A; Lake, Jason P

    2017-09-01

    The aim of this study was to examine the effects of barbell load on countermovement vertical jump (CMJ) power and net impulse within a theoretically valid framework, cognisant of the underpinning force, temporal, and spatial components. A total of 24 resistance-trained rugby union athletes (average ± SD: age: 23.1 ± 3.4 years; height: 1.83 ± 0.05 m; body mass (BM): 91.3 ± 10.5 kg) performed maximal CMJ under 5 experimental conditions in a randomised, counterbalanced order: unloaded, and with additional loads of 25%, 50%, 75%, and 100% of BM. Peak power and average power were maximised during the unloaded condition, both decreasing significantly (P barbell load and the underpinning force, time, and displacement components should be considered by strength and conditioning coaches when prescribing barbell loads.

  13. Stopped-flow studies of spectral changes in bilirubin-human serum albumin following an alkaline pH jump and following binding of bilirubin

    DEFF Research Database (Denmark)

    Honoré, B

    1987-01-01

    A stopped-flow technique was used to study the spectral changes occurring in bilirubin-albumin following a pH jump as well as following binding of bilirubin at 25 degrees C. The changes were studied in two wavelength ranges, 280-310 nm (tyrosine residues) and 400-510 nm (bound bilirubin). The cha...

  14. Jumping and Hopping in Elite and Amateur Orienteering Athletes and Correlations to Sprinting and Running

    DEFF Research Database (Denmark)

    Hébert-Losier, Kim; Jensen, Kurt; Holmberg, Hans-Christer

    2014-01-01

    PURPOSE: Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlations...... with sprinting and/or running have been examined in orienteering athletes. METHODS: We investigated squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), and hopping performed by 8 elite and 8 amateur male foot-orienteering athletes (29 ± 7 y, 183 ± 5 cm, 73 ± 7 kg) and possible correlations...

  15. Effects of fatigue and surface instability on neuromuscular performance during jumping.

    Science.gov (United States)

    Lesinski, M; Prieske, O; Demps, M; Granacher, U

    2016-10-01

    It has previously been shown that fatigue and unstable surfaces affect jump performance. However, the combination thereof is unresolved. Thus, the purpose of this study was to examine the effects of fatigue and surface instability on jump performance and leg muscle activity. Twenty elite volleyball players (18 ± 2 years) performed repetitive vertical double-leg box jumps until failure. Before and after a fatigue protocol, jump performance (i.e., jump height) and electromyographic activity of selected lower limb muscles were recorded during drop jumps (DJs) and countermovement jumps (CMJs) on a force plate on stable and unstable surfaces (i.e., balance pad on top of force plate). Jump performance (3-7%; P muscle activity (2-27%; P fatigue during DJs and CMJs, and on unstable compared with stable surfaces during DJs only (jump performance: 8%; P muscle activity: 9-25%; P fatigue by surface condition were observed. Our findings revealed that fatigue impairs neuromuscular performance during DJs and CMJs in elite volleyball players, whereas surface instability affects neuromuscular DJ performance only. Absent fatigue × surface interactions indicate that fatigue-induced changes in jump performance are similar on stable and unstable surfaces in jump-trained athletes. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Effect of cluster sets on plyometric jump power.

    Science.gov (United States)

    Moreno, Steven D; Brown, Lee E; Coburn, Jared W; Judelson, Daniel A

    2014-09-01

    Cluster sets may lead to enhanced power (PW) production by allowing for partial recovery. The purpose of this study was to determine the effects of cluster sets vs. traditional sets on plyometric jump PW, ground reaction force, take-off velocity (TOV), and jump height (JH). Twenty-six recreationally trained college men completed 3 testing sessions, which involved performing repeated body-weight (BW) plyometric squat jumps across 3 different set configurations: traditional (2 sets of 10 with 90-second rest between sets), cluster 1 (4 sets of 5 with 30-second rest between sets), and cluster 2 (10 sets of 2 with 10-second rest between sets). Ground reaction force results demonstrated no interaction or main effect for condition, but there was a significant (p ≤ 0.05) main effect for repetition, where repetition 1 was significantly less than repetitions 3-5, 7-10, 12-15, and 17-20. For TOV, PW, and JH, there were significant interactions. Take-off velocity resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 7-10 and 17-20, but was significantly less than repetition 13; cluster 1, repetition 1 was significantly less than repetitions 2-5; and cluster 2, there were no significant differences. Power resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 4-10 and 14-20; cluster 1, repetition 1 was significantly greater than repetitions 7-10 and 12-20; and cluster 2, repetition 1 was significantly greater than repetitions 3, 6-18, and 20. Jump height resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 18-20, but was significantly less than repetitions 3 and 13. For cluster 1 and cluster 2, there were no significant differences. These results demonstrate that cluster sets, specifically 10 sets of 2, allow for a greater maintenance of PW, TOV, and JH compared with a traditional 2 sets of 10 when performing repeated BW plyometric squat jumps. A lack

  17. Dynamic Jump Intensities and Risk Premiums in Crude Oil Futures and Options Markets

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Li, Bingxin

    2016-01-01

    Options on crude oil futures are the most actively traded commodity options. We develop a class of computationally efficient discrete-time jump models that allow for closed-form option valuation, and we use crude oil futures and options data to investigate the economic importance of jumps...... and dynamic jump intensities in these markets. Allowing for jumps is crucial for modeling crude oil futures and futures options, and we find evidence in favor of time-varying jump intensities. During crisis periods, jumps occur more frequently. The properties of the jump processes implied by the option data...... differ from those implied by the futures data, which may be due to improved parameter identification....

  18. Underweight in ski jumping: The solution of the problem.

    Science.gov (United States)

    Müller, W; Gröschl, W; Müller, R; Sudi, K

    2006-11-01

    Underweight is becoming increasingly prevalent in many sports. Among world class ski jumpers, the body mass index BMI has decreased by 4 units since 1970. The BMI ignores different body properties of individuals. Particular care should be taken in groups with unusual leg length to avoid classifying them inappropriately as thin or overweight (WHO). The improved measure MI (mass index) for relative body weight overcomes this shortcoming. Anthropometric data of ski jumpers was collected during the Olympic Games in Salt Lake City (2002; participation 81 %, n = 57), during the Summer Grand Prix in Hinterzarten (2000; participation 100 %, n = 92), and during the World Cup in Planica (2000; n = 56). The BMI and the MI were determined. The MI considers the individual leg length: A person with longer legs than average has an MI > BMI, and vice versa: MI = 0.28 m/s2 (m: mass in kg, s: sitting height in meters). BMI classes of ski jumpers in the season 2004/2005 were calculated from their official individual ski length limitation which is a function of their BMI. BMI means were 19.84 in Planica, 19.58 in Hinterzarten, and 19.43 kg m(-2) in SLC. Lowest BMI was 16.4 kg m(-2). The percentage of underweight ski jumpers (BMI ski jumping regulations. The ratio s/h = C (s = sitting height, h = height, C = cormic index) ranged from 0.49 to 0.57. Accordingly, the MI values (which are leg length corrected BMI values according to MI = BMI (C /C) (k) with k = 2 and C = 0.53) deviated remarkably from BMI values. For the 49 cases with BMI or MI or both below 18.5 kg m(-2), the classification to be underweight or not changed in 69 % when the MI was used instead of the BMI. Underweight or overweight is not only a question of cut-off points; the measure used determines the classification accuracy. A substantial improvement of weight analyses in sports medicine, public health, and general medicine as well can be obtained by using the MI instead of the BMI.

  19. Laser induced temperature jump investigations of fast protein folding dynamics

    Science.gov (United States)

    Qiu, Linlin

    Protein folding has a large parameter space, diverse mechanism, and multipath kinetics. However, there are some common features many proteins share in their folding processes: all seem to fold at the rates much faster than the random conformation search, and all fold into the structures which have the highly regular motifs like alpha-helices, beta-sheets and turns. Understanding how fast proteins can fold is one of the central issues in solving the protein folding problem. Ultrafast folding kinetics had not been accessible until a few sub-millisecond probes were invented and applied lately. We constructed a laser induced temperature jump spectrometer which is a great utility in identifying the local structure and tertiary contact formation of proteins on the time scale from 10 -8 to 10-3 s with time resolution of 10 -9 s. With this spectrometer we studied the fast folding mini-protein, TrpCage and a few short stable beta-hairpins, the TrpZip series. Studying TrpCage was a major breakthrough it was a pioneer protein model which brought experiment and simulation very close: its structures measured by NMR and predicted by the molecular dynamics were amazingly alike. Our kinetic results showed that it folds in 4 mus at room temperature which turned out to be the fastest ever known for protein-like molecules. Also this folding time constant is consistent with what was later on simulated by distributed computation. TrpZips are among the smallest and stablest polypeptide chains which form secondary structures. They are slightly different from each other based on structural stability and by forming various types of beta-hairpins which are the minimum units of beta tertiary structure. The beta-hairpins form in the time range of 1--10 mus that confirms the theory that loop formation is controlled by the diffusion process (˜mus). We also investigated the kinetics of the protein chain collapse, a very controversial problem. By comparing the collapse of the foldable 104

  20. Vertical jump performance in Italian male and female national team soccer players.

    Science.gov (United States)

    Castagna, Carlo; Castellini, Elena

    2013-04-01

    The aim of this study was to examine the validity of vertical jump (VJ) performance variables in elite-standard male and female Italian soccer players. One hundred eighteen national team soccer players (n = 56 men and n = 62 women) were tested for countermovement (CMJ) and squatting jump (SJ) heights. The stretch-shortening cycle efficiency (SSCE) was assessed as percentage of CMJ gain over SJ ([INCREMENT]CMJ-SJ), difference (CMJ-SJ), and ratio (CMJ:SJ). Results showed significant sex difference in SJ and CMJ. Differences in SSCE were mainly in the absolute variables between sexes. Cutoff values for CMJ and SJ using sex as construct were 34.4 and 32.9 cm, respectively. No competitive level differences in VJ performance were detected in the male players. Female national team players showed VJ performance higher than the under 17 counterpart. The results of this study showed that VJ performance could not discriminate between competitive levels in male national team-selected soccer players. However, the use of CMJ and SJ normative data may help strength and conditioning coaches in prescribing lower limb explosive strength training in elite soccer players. In this, variations in VJ performance in the range of approximately 1 cm may be regarded as of interest in tracking noncasual variation in elite-standard soccer players.

  1. Interrater and Intrarater Reliability of the Tuck Jump Assessment by Health Professionals of Varied Educational Backgrounds

    Directory of Open Access Journals (Sweden)

    Lisa A. Dudley

    2013-01-01

    Full Text Available Objective. The Tuck Jump Assessment (TJA, a clinical plyometric assessment, identifies 10 jumping and landing technique flaws. The study objective was to investigate TJA interrater and intrarater reliability with raters of different educational and clinical backgrounds. Methods. 40 participants were video recorded performing the TJA using published protocol and instructions. Five raters of varied educational and clinical backgrounds scored the TJA. Each score of the 10 technique flaws was summed for the total TJA score. Approximately one month later, 3 raters scored the videos again. Intraclass correlation coefficients determined interrater (5 and 3 raters for first and second session, resp. and intrarater (3 raters reliability. Results. Interrater reliability with 5 raters was poor (ICC = 0.47; 95% confidence intervals (CI 0.33–0.62. Interrater reliability between 3 raters who completed 2 scoring sessions improved from 0.52 (95% CI 0.35–0.68 for session one to 0.69 (95% CI 0.55–0.81 for session two. Intrarater reliability was poor to moderate, ranging from 0.44 (95% CI 0.22–0.68 to 0.72 (95% CI 0.55–0.84. Conclusion. Published protocol and training of raters were insufficient to allow consistent TJA scoring. There may be a learned effect with the TJA since interrater reliability improved with repetition. TJA instructions and training should be modified and enhanced before clinical implementation.

  2. Minimizing tip-sample forces in jumping mode atomic force microscopy in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Esteban, A. [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Horcas, I. [Nanotec Electronica S.L., Centro Empresarial Euronova 3, Ronda de Poniente 12, 28760 Tres Cantos, Madrid (Spain); Hernando-Perez, M. [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Ares, P. [Nanotec Electronica S.L., Centro Empresarial Euronova 3, Ronda de Poniente 12, 28760 Tres Cantos, Madrid (Spain); Perez-Berna, A.J.; San Martin, C.; Carrascosa, J.L. [Centro Nacional de Biotecnologia (CNB-CSIC), Darwin 3, 28049 Madrid (Spain); Pablo, P.J. de [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Gomez-Herrero, J., E-mail: julio.gomez@uam.es [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2012-03-15

    Control and minimization of tip-sample interaction forces are imperative tasks to maximize the performance of atomic force microscopy. In particular, when imaging soft biological matter in liquids, the cantilever dragging force prevents identification of the tip-sample mechanical contact, resulting in deleterious interaction with the specimen. In this work we present an improved jumping mode procedure that allows detecting the tip-sample contact with high accuracy, thus minimizing the scanning forces ({approx}100 pN) during the approach cycles. To illustrate this method we report images of human adenovirus and T7 bacteriophage particles which are prone to uncontrolled modifications when using conventional jumping mode. -- Highlights: Black-Right-Pointing-Pointer Improvement in atomic force microscopy in buffer solution. Black-Right-Pointing-Pointer Peak force detection. Black-Right-Pointing-Pointer Subtracting the cantilever dragging force. Black-Right-Pointing-Pointer Forces in the 100 pN range. Black-Right-Pointing-Pointer Imaging of delicate viruses with atomic force microscopy.

  3. Option Pricing with Stochastic Volatility and Jump Diffusion Processes

    Directory of Open Access Journals (Sweden)

    Radu Lupu

    2006-05-01

    Full Text Available Option pricing by the use of Black Scholes Merton (BSM model is based on the assumption that asset prices have a lognormal distribution. In spite of the use of these models on a large scale, both by practioners and academics, the assumption of lognormality is rejected by the history of returns. The objective of this article is to present the methods that developed after the Black Scholes Merton environment and deals with the option pricing model adjustment to the empirical properties of asset returns. The main models that appeared after BSM allowed for special changes of the returns that materialized in jump-diffusion and stochastic volatility processes. The article presents the foundations of risk neutral options evaluation and the empirical evidence that fed the amendment of the lognormal assumption in the first part and shows the evaluation procedure under the assumption of stock prices following the jump-diffusion process and the stochastic volatility process.

  4. Control and filtering for semi-Markovian jump systems

    CERN Document Server

    Li, Fanbiao; Wu, Ligang

    2017-01-01

    This book presents up-to-date research developments and novel methodologies on semi-Markovian jump systems (S-MJS). It presents solutions to a series of problems with new approaches for the control and filtering of S-MJS, including stability analysis, sliding mode control, dynamic output feedback control, robust filter design, and fault detection. A set of newly developed techniques such as piecewise analysis method, positively invariant set approach, event-triggered method, and cone complementary linearization approaches are presented. Control and Filtering for Semi-Markovian Jump Systems is a comprehensive reference for researcher and practitioners working in control engineering, system sciences and applied mathematics, and is also a useful source of information for senior undergraduates and graduates in these areas. The readers will benefit from some new concepts, new models and new methodologies with practical significance in control engineering and signal processing.

  5. Age distribution dynamics with stochastic jumps in mortality.

    Science.gov (United States)

    Calabrese, Salvatore; Porporato, Amilcare; Laio, Francesco; D'Odorico, Paolo; Ridolfi, Luca

    2017-11-01

    While deterministic age distribution models have been extensively studied and applied in various disciplines, little work has been devoted to understanding the role of stochasticity in birth and mortality terms. In this paper, we analyse a stochastic M'Kendrick-von Foerster equation in which jumps in mortality represent intense losses of population due to external events. We present explicit solutions for the probability density functions of the age distribution and the total population and for the temporal dynamics of their moments. We also derive the dynamics of the mean age of the population and its harmonic mean. The framework is then used to calculate the age distribution of salt in the soil root zone, where the accumulation of salt by atmospheric deposition is counteracted by plant uptake and by jump losses due to percolation events.

  6. Coalescence-Induced Jumping of Nanodroplets on Textured Surfaces.

    Science.gov (United States)

    Gao, Shan; Liao, Quanwen; Liu, Wei; Liu, Zhichun

    2018-01-04

    Conducting experimental studies on nanoscale droplet coalescence using traditional microscopes is a challenging research topic, and views differ as to whether the spontaneous removal can occur in the coalescing nanodroplets. Here, a molecular dynamics simulation is carried out to investigate the coalescence process of two equally sized nanodroplets. On the basis of atomic coordinates, we compute the liquid bridge radii for various cases, which is described by a power law of spreading time, and these nanodroplets undergo coalescence in the inertially limited-viscous regime. Moreover, coalescence-induced jumping is also possible for the nanodroplets, and the attraction force between surface and water molecules plays a crucial role in this process, where the merged nanodroplets prefer to jump away from those surfaces with lower attraction force. When the solid-liquid interaction intensity and surface structure parameters are varied, the attraction force is shown to decrease with decreasing surface wettability intensity and solid fraction.

  7. Option Pricing with Stochastic Volatility and Jump Diffusion Processes

    Directory of Open Access Journals (Sweden)

    Radu Lupu

    2006-03-01

    Full Text Available Option pricing by the use of Black Scholes Merton (BSM model is based on the assumption that asset prices have a lognormal distribution. In spite of the use of these models on a large scale, both by practioners and academics, the assumption of lognormality is rejected by the history of returns. The objective of this article is to present the methods that developed after the Black Scholes Merton environment and deals with the option pricing model adjustment to the empirical properties of asset returns. The main models that appeared after BSM allowed for special changes of the returns that materialized in jump-diffusion and stochastic volatility processes. The article presents the foundations of risk neutral options evaluation and the empirical evidence that fed the amendment of the lognormal assumption in the first part and shows the evaluation procedure under the assumption of stock prices following the jump-diffusion process and the stochastic volatility process.

  8. Exponential Stability of Stochastic Systems with Delay and Poisson Jumps

    Directory of Open Access Journals (Sweden)

    Wenli Zhu

    2014-01-01

    Full Text Available This paper focuses on the model of a class of nonlinear stochastic delay systems with Poisson jumps based on Lyapunov stability theory, stochastic analysis, and inequality technique. The existence and uniqueness of the adapted solution to such systems are proved by applying the fixed point theorem. By constructing a Lyapunov function and using Doob’s martingale inequality and Borel-Cantelli lemma, sufficient conditions are given to establish the exponential stability in the mean square of such systems, and we prove that the exponentially stable in the mean square of such systems implies the almost surely exponentially stable. The obtained results show that if stochastic systems is exponentially stable and the time delay is sufficiently small, then the corresponding stochastic delay systems with Poisson jumps will remain exponentially stable, and time delay upper limit is solved by using the obtained results when the system is exponentially stable, and they are more easily verified and applied in practice.

  9. BIOMECHANICAL ANALYSIS OF RUNNING IN THE HIGH JUMP

    Directory of Open Access Journals (Sweden)

    Werlayne Leite

    2013-02-01

    Full Text Available The aim of this paper is to analyze the biomechanics of running at high jump. To this study was realized a bibliographic revision. The running phase is the one which starts when the athlete is set in movement for the jump until the moment that he touches the ground with the takeoff foot in front of the bar, this phase can be divided into two parts: the running in straight line and the running in curve. On the other hand, for better understanding and due to a biomechanical complexity, the running in curve will be divided into three other parts: the three last strides, the two last strides and the last strides. Besides that, we could mention important factors for an efficient approach run: the radius of the curve, the distance and length of the takeoff run.

  10. Forecasting Exchange Rate Volatility in the Presence of Jumps

    DEFF Research Database (Denmark)

    Busch, Thomas; Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    We study measures of foreign exchange rate volatility based on high-frequency (5-minute) $/DM exchange rate returns using recent nonparametric statistical techniquesto compute realized return volatility and its separate continuous sample path and jumpcomponents, and measures based on prices...... of exchange rate futures options, allowingcalculation of option implied volatility. We find that implied volatility is an informationallyefficient but biased forecast of future realized exchange rate volatility. Furthermore,we show that log-normality is an even better distributional approximation...... for impliedvolatility than for realized volatility in this market. Finally, we show that the jump componentof future realized exchange rate volatility is to some extent predictable, and thatoption implied volatility is the dominant forecast of the future jump component....

  11. VaR: Exchange Rate Risk and Jump Risk

    Directory of Open Access Journals (Sweden)

    Fen-Ying Chen

    2010-01-01

    Full Text Available Incorporating the Poisson jumps and exchange rate risk, this paper provides an analytical VaR to manage market risk of international portfolios over the subprime mortgage crisis. There are some properties in the model. First, different from past studies in portfolios valued only in one currency, this model considers portfolios not only with jumps but also with exchange rate risk, that is vital for investors in highly integrated global financial markets. Second, in general, the analytical VaR solution is more accurate than historical simulations in terms of backtesting and Christoffersen's independence test (1998 for small portfolios and large portfolios. In other words, the proposed model is reliable not only for a portfolio on specific stocks but also for a large portfolio. Third, the model can be regarded as the extension of that of Kupiec (1999 and Chen and Liao (2009.

  12. Differential Algebraic Equations of MOS Circuits and Jump Behavior

    Science.gov (United States)

    Sarangapani, P.; Thiessen, T.; Mathis, W.

    2012-10-01

    Many nonlinear electronic circuits showing fast switching behavior exhibit jump effects which occurs when the state space of the electronic system contains a fold. This leads to difficulties during the simulation of these systems with standard circuit simulators. A method to overcome these problems is by regularization, where parasitic inductors and capacitors are added at the suitable locations. However, the transient solution will not be reliable if this regularization is not done in accordance with Tikhonov's Theorem. A geometric approach is taken to overcome these problems by explicitly computing the state space and jump points of the circuit. Until now, work has been done in analyzing example circuits exhibiting this behavior for BJT transistors. In this work we apply these methods to MOS circuits (Schmitt trigger, flip flop and multivibrator) and present the numerical results. To analyze the circuits we use the EKV drain current model as equivalent circuit model for the MOS transistors.

  13. AGS Fast spin resonance jump, magnets and power supplies

    International Nuclear Information System (INIS)

    Glenn, J.W.; Huang, H.; Liaw, C. J.; Marneris, I.; Meng, W.; Mi, J. L.; Rosas, P.; Sandberg, J.; Tuozzolo, J.; Zhang, A.

    2009-01-01

    In order to cross more rapidly the 82 weak spin resonances caused by the horizontal tune and the partial snakes, we plan to jump the horizontal tune 82 times during the acceleration of polarized protons. The current in the magnets creating this tune jump will rise in 100 (micro)s, hold flat for about 4 ms and fan to zero in 100 (micro)s. Laminated beam transport quadrupole magnets have been recycled by installing new two turn coils and longitudinal laminated pole tip shims that reduce inductance and power supply current. The power supply uses a high voltage capacitor discharge to raise the magnet current, which is then switched to a low voltage supply, and then the current is switched back to the high voltage capacitor to zero the current. The current in each of the magnet pulses must match the order of magnitude change in proton momentum during the acceleration cycle. The magnet, power supply and operational experience are described

  14. Price jumps in Visegrad country stock markets: an empirical analysis

    Czech Academy of Sciences Publication Activity Database

    Novotný, Jan

    -, č. 412 (2010), s. 1-33 ISSN 1211-3298 R&D Projects: GA ČR(CZ) GA402/08/1376; GA MŠk LC542 Grant - others:MŠk(CZ) SVV-2010-261801 Institutional research plan: CEZ:MSM0021620846 Keywords : financial market s * Visegrad region * price jumps Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp412.pdf

  15. LOAD THAT MAXIMIZES POWER OUTPUT IN COUNTERMOVEMENT JUMP

    Directory of Open Access Journals (Sweden)

    Pedro Jimenez-Reyes

    2016-02-01

    Full Text Available ABSTRACT Introduction: One of the main problems faced by strength and conditioning coaches is the issue of how to objectively quantify and monitor the actual training load undertaken by athletes in order to maximize performance. It is well known that performance of explosive sports activities is largely determined by mechanical power. Objective: This study analysed the height at which maximal power output is generated and the corresponding load with which is achieved in a group of male-trained track and field athletes in the test of countermovement jump (CMJ with extra loads (CMJEL. Methods: Fifty national level male athletes in sprinting and jumping performed a CMJ test with increasing loads up to a height of 16 cm. The relative load that maximized the mechanical power output (Pmax was determined using a force platform and lineal encoder synchronization and estimating the power by peak power, average power and flight time in CMJ. Results: The load at which the power output no longer existed was at a height of 19.9 ± 2.35, referring to a 99.1 ± 1% of the maximum power output. The load that maximizes power output in all cases has been the load with which an athlete jump a height of approximately 20 cm. Conclusion: These results highlight the importance of considering the height achieved in CMJ with extra load instead of power because maximum power is always attained with the same height. We advise for the preferential use of the height achieved in CMJEL test, since it seems to be a valid indicative of an individual's actual neuromuscular potential providing a valid information for coaches and trainers when assessing the performance status of our athletes and to quantify and monitor training loads, measuring only the height of the jump in the exercise of CMJEL.

  16. Incomplete Financial Markets and Jumps in Asset Prices

    DEFF Research Database (Denmark)

    Crès, Hervé; Markeprand, Tobias Ejnar; Tvede, Mich

    A dynamic pure-exchange general equilibrium model with uncertainty is studied. Fundamentals are supposed to depend continuously on states of nature. It is shown that: 1. if financial markets are complete, then asset prices vary continuously with states of nature, and; 2. if financial markets...... are incomplete, jumps in asset prices may be unavoidable. Consequently incomplete financial markets may increase volatility in asset prices significantly....

  17. Bayesian conformational analysis of ring molecules through reversible jump MCMC

    DEFF Research Database (Denmark)

    Nolsøe, Kim; Kessler, Mathieu; Pérez, José

    2005-01-01

    In this paper we address the problem of classifying the conformations of mmembered rings using experimental observations obtained by crystal structure analysis. We formulate a model for the data generation mechanism that consists in a multidimensional mixture model. We perform inference...... for the proportions and the components in a Bayesian framework, implementing an MCMC Reversible Jumps Algorithm to obtain samples of the posterior distributions. The method is illustrated on a simulated data set and on real data corresponding to cyclo-octane structures....

  18. Fundamental Studies of Jumping-Drop Thermal Diodes

    Science.gov (United States)

    2016-02-29

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0002 TR-2016-0002 FUNDAMENTAL STUDIES OF JUMPING-DROP THERMAL DIODES Chuan-Hua Chen Duke...formulated or supplied the drawings, specifications, or other data does not license the holder or any other person or corporation; or convey any rights or...permission to manufacture, use, or sell any patented invention that may relate to them. This report is the result of contracted fundamental

  19. CONNECTION OF FUNCTIONAL ABILITIES WITH JUMPING AND THROWING ATHLETIC DISCIPLINES

    OpenAIRE

    Igor Stanojević; Dejan Milenković

    2014-01-01

    The aim of this study was to determine the connection between functional abilities with results of jumping and throwing athletic disciplines with athletes. The sample was taken from a population of elementary school students from Prokuplje region, 13 and 14 old, included in regular physical education classes. The sample consisted of 200 male athletes involved in the training process in sports clubs at least three times a week in addition to physical education classes. For assessment of functi...

  20. Numerical Analysis for Stochastic Partial Differential Delay Equations with Jumps

    OpenAIRE

    Li, Yan; Hu, Junhao

    2013-01-01

    We investigate the convergence rate of Euler-Maruyama method for a class of stochastic partial differential delay equations driven by both Brownian motion and Poisson point processes. We discretize in space by a Galerkin method and in time by using a stochastic exponential integrator. We generalize some results of Bao et al. (2011) and Jacob et al. (2009) in finite dimensions to a class of stochastic partial differential delay equations with jumps in infinite dimensions.

  1. The Economics of Bitcoins - Market Characteristics and Price Jumps

    OpenAIRE

    Gronwald, Marc

    2014-01-01

    This paper deals with the economics of Bitcoins in two ways. First, it broadens the discussion on how to capture Bitcoins using economic terms. Center stage in this analysis take the discussion of some unique characteristics of this market as well as the comparison of Bitcoins and gold. Second, the paper empirically analyses Bitcoin prices using an autoregressive jump-intensity GARCH model; a model tested and proven by the empirical finance community. Results suggest that Bitcoin price are pa...

  2. Do co-jumps impact correlations in currency markets?

    Czech Academy of Sciences Publication Activity Database

    Baruník, J.; Vácha, Lukáš

    2018-01-01

    Roč. 37, č. 1 (2018), s. 97-119 ISSN 1386-4181 Grant - others:GA ČR GA16-14151S Institutional support: RVO:67985556 Keywords : Co-jumps * Currency markets * Realized covariance * Wavelets * Bootstrap Subject RIV: AH - Economics OBOR OECD: Finance Impact factor: 1.134, year: 2016 http://library.utia.cas.cz/separaty/2018/E/vacha-0487659.pdf

  3. The beginning of time observed in quantum jumps

    Energy Technology Data Exchange (ETDEWEB)

    Bohm, Arno [CCQS, Physics Department, University of Texas, Austin, TX (United States); Bryant, Peter W. [IBM Research, Rio de Janeiro (Brazil); Uncu, Haydar [Department of Physics, Adnan Menderes University, Aydin (Turkey); Wickramasekara, Sujeev [Department of Physics, Grinnell College, Grinnell, IA (United States); Schleich, Wolfgang P. [Institut fuer Quantenphysik and Center for Integrated Quantum Science and Technology, Universitaet Ulm (Germany); Hagler Institute for Advanced Study, Texas A and M University, College Station, TX (United States); Texas A and M AgriLife, Institute for Quantum Science and Engineering (IQSE) and Department of Physics and Astronomy, Texas A and M University, College Station, TX (United States)

    2017-06-15

    The phenomenon of quantum jumps observed in a single ion stored in a trap brings to light intimate connections between three different concepts of quantum physics: (i) quantum state trajectories, (ii) Gamow states, and (iii) the arrow of time. In particular, it allows us to identify the starting time of the semigroup time evolution. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Visual Discrimination Learning in the Jumping Spider Phidippus regius

    OpenAIRE

    Massimo De Agrò; Lucia Regolin; Enzo Moretto

    2017-01-01

    Over the past decade, research in comparative psychology has increasingly focused on non-vertebrate models of cognition. Jumping spiders provide excellent models for the study of visually mediated behaviors, such as associative learning or the navigation of complex environments. Here, we tested visual and memory abilities of Phidippus regius to discriminate between artificial geometrical stimuli and to generalize the learned discrimination to illusory stimuli, using the amodal completion mech...

  5. A resistance band increased internal hip abduction moments and gluteus medius activation during pre-landing and early-landing.

    Science.gov (United States)

    Dai, Boyi; Heinbaugh, Erika M; Ning, Xiaopeng; Zhu, Qin

    2014-11-28

    An increased knee abduction angle during jump-landing has been identified as a risk factor for anterior cruciate ligament injuries. Activation of the hip abductors may decrease the knee abduction angle during jump-landing. The purpose of this study was to examine the effects of a resistance band on the internal hip abduction moment and gluteus medius activation during the pre-landing (100ms before initial contact) and early-landing (100ms after initial contact) phases of a jump-landing-jump task. Thirteen male and 15 female recreational athletes (age: 21.1±2.4yr; mass: 73.8±14.6kg; height: 1.76±0.1m) participated in the study. Subjects performed jump-landing-jump tasks with or without a resistance band applied to their lower shanks. During the with-band condition, subjects were instructed to maintain their movement patterns as performing the jump-landing task without a resistance band. Lower extremity kinematics, kinetics, and gluteus medius electromyography (EMG) were collected. Applying the band increased the average hip abduction moment during pre-landing (pgluteus medius EMG during pre-landing (pgluteus medius during jump-landing. Additional instructions and feedback regarding hip abduction, hip flexion, and knee flexion may be required to minimize negative changes to other kinematic variables. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Ski jumping takeoff in a wind tunnel with skis.

    Science.gov (United States)

    Virmavirta, Mikko; Kivekäs, Juha; Komi, Paavo

    2011-11-01

    The effect of skis on the force-time characteristics of the simulated ski jumping takeoff was examined in a wind tunnel. Takeoff forces were recorded with a force plate installed under the tunnel floor. Signals from the front and rear parts of the force plate were collected separately to examine the anteroposterior balance of the jumpers during the takeoff. Two ski jumpers performed simulated takeoffs, first without skis in nonwind conditions and in various wind conditions. Thereafter, the same experiments were repeated with skis. The jumpers were able to perform very natural takeoff actions (similar to the actual takeoff) with skis in wind tunnel. According to the subjective feeling of the jumpers, the simulated ski jumping takeoff with skis was even easier to perform than the earlier trials without skis. Skis did not much influence the force levels produced during the takeoff but they still changed the force distribution under the feet. Contribution of the forces produced under the rear part of the feet was emphasized probably because the strong dorsiflexion is needed for lifting the skis to the proper flight position. The results presented in this experiment emphasize that research on ski jumping takeoff can be advanced by using wind tunnels.

  7. Aerodynamics of ski jumping flight and its control: II. Simulations

    Science.gov (United States)

    Lee, Jungil; Lee, Hansol; Kim, Woojin; Choi, Haecheon

    2015-11-01

    In a ski jumping competition, it is essential to analyze the effect of various posture parameters of a ski jumper to achieve a longer flight distance. For this purpose, we conduct a large eddy simulation (LES) of turbulent flow past a model ski jumper which is obtained by 3D scanning a ski jumper's body (Mr. Chil-Ku Kang, member of the Korean national team). The angle of attack of the jump ski is 30° and the Reynolds number based on the length of the jump ski is 540,000. The flow statistics including the drag and lift coefficients in flight are in good agreements with our own experimental data. We investigate the flow characteristics such as the flow separation and three-dimensional vortical structures and their effects on the drag and lift. In addition to LES, we construct a simple geometric model of a ski jumper where each part of the ski jumper is modeled as a canonical bluff body such as the sphere, cylinder and flat plate, to find its optimal posture. The results from this approach will be compared with those by LES and discussed. Supported by NRF program (2014M3C1B1033848, 2014R1A1A1002671).

  8. Kinematic Chains in Ski Jumping In-run Posture.

    Science.gov (United States)

    Janurová, Eva; Janura, Miroslav; Cabell, Lee; Svoboda, Zdeněk; Vařeka, Ivan; Elfmark, Milan

    2013-12-18

    The concept of kinematic chains has been systematically applied to biological systems since the 1950s. The course of a ski jump can be characterized as a change between closed and open kinematic chains. The purpose of this study was to determine a relationship between adjacent segments within the ski jumper's body's kinematic chain during the in-run phase of the ski jump. The in-run positions of 267 elite male ski jumpers who participated in the FIS World Cup events in Innsbruck, Austria, between 1992 and 2001 were analyzed (656 jumps). Two-dimensional (2-D) kinematic data were collected from the bodies of the subjects. Relationships between adjacent segments of the kinematic chain in the ski jumper's body at the in-run position are greater nearer the chain's ground contact. The coefficient of determination between the ankle and knee joint angles is 0.67. Changes in the segments' positions in the kinematic chain of the ski jumper's body are stable during longitudinal assessment. Changes in shank and thigh positions, in the sense of increase or decrease, are the same.

  9. NONINVASIVE DETERMINATION OF KNEE CARTILAGE DEFORMATION DURING JUMPING

    Directory of Open Access Journals (Sweden)

    Djordje Kosanic

    2009-12-01

    Full Text Available The purpose of this investigation was to use a combination of image processing, force measurements and finite element modeling to calculate deformation of the knee cartilage during jumping. Professional athletes performed jumps analyzed using a force plate and high-speed video camera system. Image processing was performed on each frame of video using a color recognition algorithm. A simplified mass-spring-damper model was utilized for determination of global force and moment on the knee. Custom software for fitting the coupling characteristics was created. Simulated results were used as input data for the finite element calculation of cartilage deformation in the athlete's knee. Computer simulation data was compared with the average experimental ground reaction forces. The results show the three-dimensional mechanical deformation distribution inside the cartilage volume. A combination of the image recognition technology, force plate measurements and the finite element cartilage deformation in the knee may be used in the future as an effective noninvasive tool for prediction of injury during jumping

  10. Macroscopic wettability based on an interfacial jump condition.

    Science.gov (United States)

    Yonemoto, Yukihiro; Kunugi, Tomoaki

    2010-05-01

    Young's equation, describing an interfacial equilibrium condition of a liquid droplet on a smooth solid surface, raises issues concerning the existence of a sine term which has not yet been resolved theoretically and continues to be discussed to the present day. From a thermodynamics viewpoint, the equilibrium condition arises by minimizing the total free energy of the system while intensive parameters are kept constant. In the derivation, variations in the virtual work in both horizontal and vertical directions of the droplet on the smooth solid are considered. From a hydrodynamics viewpoint, there is a momentum jump condition at the gas-liquid interface that is derived based on a mechanical balance. Using standard mathematical procedures such as Stokes' theorem and differential geometry, a test volume is considered across the interface between two continuous phases from which the jump condition is derived. In the present paper, Young's equation is revisited from the point of view of the momentum jump condition at the two-phase interface and a modified Young's equation is derived. The analytical solution derived from the modified Young's equation is then used to compare theory with experimental data. The line tension and contact angle for a lens droplet are also discussed on the basis of this model.

  11. INCREASED DISTANCE OF SHOOTING ON BASKETBALL JUMP SHOT

    Directory of Open Access Journals (Sweden)

    Victor Hugo Alves Okazaki

    2012-06-01

    Full Text Available The present study analyzed the effect of increased distance on basketball jump shot outcome and performance. Ten male expert basketball players were filmed and a number of kinematic variables analyzed during jump shot that were performed from three conditions to represent close, intermediate and far distances (2.8, 4.6, and 6.4m, respectively. Shot accuracy decreased from 59% (close to 37% (far, in function of the task constraints (p < 0.05. Ball release height decreased (p < 0.05 from 2.46 m (close to 2.38m (intermediate and to 2.33m (long. Release angle also decreased (p < 0.05 when shot was performed from close (78.92° in comparison to intermediate distances (65.60°. While, ball release velocity increased (p < 0.05 from 4.39 m/s (close to 5.75 m·s-1 (intermediate to 6.89 m·s-1 (far. These changes in ball release height, angle and velocity, related to movement performance adaptations were suggested as the main factors that influence jump shot accuracy when distance is augmented

  12. Increased distance of shooting on basketball jump shot.

    Science.gov (United States)

    Okazaki, Victor Hugo Alves; Rodacki, André Luiz Félix

    2012-01-01

    The present study analyzed the effect of increased distance on basketball jump shot outcome and performance. Ten male expert basketball players were filmed and a number of kinematic variables analyzed during jump shot that were performed from three conditions to represent close, intermediate and far distances (2.8, 4.6, and 6.4m, respectively). Shot accuracy decreased from 59% (close) to 37% (far), in function of the task constraints (p shot was performed from close (78.92°) in comparison to intermediate distances (65.60°). While, ball release velocity increased (p jump shot accuracy when distance is augmented. Key pointsThe increased distance leads to greater spatial con-straint over shot movement that demands an adapta-tion of the movement for the regulation of the accu-racy and the impulse generation to release the ball.The reduction in balls release height and release angle, in addition to the increase in balls release ve-locity, were suggested as the main factors that de-creased shot accuracy with the distance increased.Players should look for release angles of shooting that provide an optimal balls release velocity to im-prove accuracy.

  13. JUMP LANDING CHARACTERISTICS IN ELITE SOCCER PLAYERS WITH CEREBRAL PALSY

    Directory of Open Access Journals (Sweden)

    Jesús Cámara

    2013-04-01

    Full Text Available The aim of the present study was to analyse the parameters that characterize the vertical ground reaction force during the landing phase of a jump, and to determine the relationship among these parameters in elite soccer players with cerebral palsy (CP. Thirteen male members of the Spanish national soccer team for people with CP (mean age: 27.1 ± 4.7 years volunteered for the study. Each participant performed three counter movement jumps. The characteristics of the first peak of the vertical ground reaction force during the landing phase of a jump, which corresponds to the forefoot contact with the ground, were similar to the results obtained in previous studies. However, a higher magnitude of rearfoot contact with the ground (F2 was observed in participants with CP than in participants without CP. Furthermore, a significant correlation between F2 magnitude and the elapsed time until its production (T2 was not observed (r = -0.474 for p = 0.102. This result implies that a landing technique based on a delay in the production of F2 might not be effective to reduce its magnitude, contrary to what has been observed in participants without CP. The absence of a significant correlation between these two parameters in the present study, and the high magnitude of F2, suggest that elite soccer players with CP should use footwear with proper cushioning characteristics.

  14. Jumping-droplet-enhanced condensation on scalable superhydrophobic nanostructured surfaces.

    Science.gov (United States)

    Miljkovic, Nenad; Enright, Ryan; Nam, Youngsuk; Lopez, Ken; Dou, Nicholas; Sack, Jean; Wang, Evelyn N

    2013-01-09

    When droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. If designed properly, these superhydrophobic nanostructured surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal nanostructured surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing surfaces at low supersaturations (heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.

  15. Jump dynamics with structural breaks for crude oil prices

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yen-Hsien [Department of Finance, Chung Yuan Christian University (China); Hu, Hsu-Ning [Department of Money, Banking and Finance, TamKang University (China); Chiou, Jer-Shiou [Department of Finance and Banking, Shih Chien University, 70 Ta-Chih Street, Taipei 104 (China)

    2010-03-15

    This study investigates the joint phenomena of permanent and transitory components in conditional variance and jump intensity along with verification of structural breaks for crude oil prices. We adopt a Component-ARJI model with structural break analysis, utilizing daily data on West Texas Intermediate crude oil spot and futures contracts. The analytical results verify the existence of permanent and transitory components in conditional variance, with the permanent component of conditional variance increasing with the occurrence of a sudden major event (such as the Iraqi Invasion of Kuwait, Operation Desert Storm and the war between the US and Iraq), and a relatively greater increase in the transitory component over the same period. Notably, jump intensity fluctuates with an increase in the transitory component of conditional variance in response to abnormal events. It is the transitory component which serves as the primary influential factor for jumps in returns; therefore, speculators are willing to take large risks, particularly with respect to anticipating future price movements, or gambling, in the hopes of rapidly making substantial gains; thus, speculators prefer the temporary volatility component and engage in trade activities. However, investors prefer the permanent volatility component, because they may well be better off relocating their assets into more stable portfolios to outperform the market portfolio over the long run. (author)

  16. Olympic weightlifting training improves vertical jump height in sportspeople: a systematic review with meta-analysis.

    Science.gov (United States)

    Hackett, Daniel; Davies, Tim; Soomro, Najeebullah; Halaki, Mark

    2016-07-01

    This systematic review was conducted to evaluate the effect of Olympic weightlifting (OW) on vertical jump (VJ) height compared to a control condition, traditional resistance training and plyometric training. Five electronic databases were searched using terms related to OW and VJ. Studies needed to include at least one OW exercise, an intervention lasting ≥6 weeks; a comparison group of control, traditional resistance training or plyometric training; and to have measured VJ height. The methodological quality of studies was assessed using the Downs and Black Checklist. Random and fixed effects meta-analyses were performed to pool the results of the included studies and generate a weighted mean effect size (ES). Six studies (seven articles) were included in the meta-analyses and described a total of 232 participants (175 athletes and 57 physical education students) with resistance training experience, aged 19.5±2.2 years. Three studies compared OW versus control; four studies compared OW versus traditional resistance training; and three studies compared OW versus plyometric training. Meta-analyses indicated OW improved VJ height by 7.7% (95% CI 3.4 to 5.4 cm) compared to control (ES=0.62, p=0.03) and by 5.1% (95% CI 2.2 to 3.0 cm) compared to traditional resistance training (ES=0.64 p=0.00004). Change in VJ height was not different for OW versus plyometric training. OW is an effective training method to improve VJ height. The similar effects observed for OW and plyometric training on VJ height suggests that either of these methods would be beneficial when devising training programmes to improve VJ height. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  17. Who ate whom? Adaptive Helicobacter genomic changes that accompanied a host jump from early humans to large felines.

    Directory of Open Access Journals (Sweden)

    Mark Eppinger

    2006-07-01

    Full Text Available Helicobacter pylori infection of humans is so old that its population genetic structure reflects that of ancient human migrations. A closely related species, Helicobacter acinonychis, is specific for large felines, including cheetahs, lions, and tigers, whereas hosts more closely related to humans harbor more distantly related Helicobacter species. This observation suggests a jump between host species. But who ate whom and when did it happen? In order to resolve this question, we determined the genomic sequence of H. acinonychis strain Sheeba and compared it to genomes from H. pylori. The conserved core genes between the genomes are so similar that the host jump probably occurred within the last 200,000 (range 50,000-400,000 years. However, the Sheeba genome also possesses unique features that indicate the direction of the host jump, namely from early humans to cats. Sheeba possesses an unusually large number of highly fragmented genes, many encoding outer membrane proteins, which may have been destroyed in order to bypass deleterious responses from the feline host immune system. In addition, the few Sheeba-specific genes that were found include a cluster of genes encoding sialylation of the bacterial cell surface carbohydrates, which were imported by horizontal genetic exchange and might also help to evade host immune defenses. These results provide a genomic basis for elucidating molecular events that allow bacteria to adapt to novel animal hosts.

  18. A review of hydraulic jump properties on both smooth and rough beds in sloping and adverse channels

    Directory of Open Access Journals (Sweden)

    M. Palermo

    2017-01-01

    Full Text Available Hydraulic jump is a phenomenon which has received significant attention in recent years and it is still studied because of its capacity to dissipate a considerable amount of the flow energy. Nevertheless, the importance of the topic still requires significant efforts from the scientific community. Namely, the prediction of the main lengths of the hydraulic jump are still an open question, as the actual knowledge on the topic does not cover all the possible configurations and boundary conditions which can usually be found in practical applications. In particular, the effects of bed roughness, bed slope, channel geometry, and air concentration on the conjugate depths ratio are still not fully understood. The present paper aims to furnish a synthetic picture of the state of art regarding the hydraulic jump properties in a wide range of both boundary conditions and geometric configurations. In particular, the analysis will be focused on the effect of both relative roughness and bed slope on the conjugate depth ratio, including the effect of air entrainment on the estimation of the effective depth. Furthermore, some predicting relationships proposed by different authors will be compared and discussed.

  19. The relative contribution of strength and physique to running and jumping performance of boys 7-11.

    Science.gov (United States)

    Ball, T E; Massey, B H; Misner, J E; McKeown, B C; Lohman, T G

    1992-12-01

    The purpose of this study was to determine the association of static strength with motor performance of 7 through 11 year old boys (N = 60) after accounting for differences in physique, i.e., body size, shape, and composition. Static strength measures included thigh extension, leg extension and plantar flexion measured by electronic transducer and back lift, leg lift, and right and left grips measured by spring dynamometer. Measures of body composition consisted of fat estimated from triceps, subscapsular and calf skinfolds, and fat-free body weight estimated from potassium-40 measurements. Body structure consisted of skeletal widths, and segment girths, lengths and volumes. The dependent variables were vertical jump, standing broad jump, 50-yard dash, 600-yard run and mile run. The measures of strength increased the variance accounted for from 10 to 23% over that when body size, composition and structure were used without strength. An exception was vertical jump where no increase in the variance accounted for was found with the addition of strength variables. The regression equations determined for the sample of 60 boys rendered multiple R's ranging from 0.64 (mile run) to 0.75 (50-yard dash). It was concluded that strength has a significant relation to motor performance and that its contribution can be better assessed after accounting for differences in body size, shape, and composition.

  20. Vertical jump, anaerobic power, and shooting accuracy are not altered 6 hours after strength training in collegiate women basketball players.

    Science.gov (United States)

    Woolstenhulme, Mandy T; Bailey, Brooke Kerbs; Allsen, Philip E

    2004-08-01

    We measured vertical jump, anaerobic power, and shooting accuracy in 18 Division I women basketball players (age 18-22 years) 6 hours following a morning strength training routine called a lift day (LD) and on a control day in which no strength training was performed. Subjects had been strength trained for 4 weeks prior to testing. The strength training session on lift day was a full-body workout and included 7 exercises performed in 3-6 sets at loads ranging from a 5 to 12 repetition maximum (RM). There were no significant differences in jump height with 2 legs (49.5 +/- 4.8 cm and 49.0 +/- 4.8 cm, LD and control, respectively), relative mean power output over 30 seconds on a Wingate bicycle test (6.4 +/- 0.8 W.kg(-1) and 6.6 +/- 0.7 W.kg(-1), LD and control, respectively), or shooting accuracy over 60 seconds (21.5 +/- 3.8 points/min and 21.3 +/- 4.1 points/min, LD and control, respectively). These data suggest that in collegiate women basketball players, a previous bout of strength training has no negative effect on vertical jump height, anaerobic power, or shooting accuracy.

  1. Intra-Personal and Inter-Personal Kinetic Synergies During Jumping

    Directory of Open Access Journals (Sweden)

    Slomka Kajetan

    2015-12-01

    Full Text Available We explored synergies between two legs and two subjects during preparation for a long jump into a target. Synergies were expected during one-person jumping. No such synergies were expected between two persons jumping in parallel without additional contact, while synergies were expected to emerge with haptic contact and become stronger with strong mechanical contact. Subjects performed jumps either alone (each foot standing on a separate force platform or in dyads (parallel to each other, each person standing on a separate force platform without any contact, with haptic contact, and with strong coupling. Strong negative correlations between pairs of force variables (strong synergies were seen in the vertical force in one-person jumps and weaker synergies in two-person jumps with the strong contact. For other force variables, only weak synergies were present in one-person jumps and no negative correlations between pairs of force variable for two-person jumps. Pairs of moment variables from the two force platforms at steady state showed positive correlations, which were strong in one-person jumps and weaker, but still significant, in two-person jumps with the haptic and strong contact. Anticipatory synergy adjustments prior to action initiation were observed in oneperson trials only. We interpret the different results for the force and moment variables at steady state as reflections of postural sway.

  2. The relationship between vertical jump power estimates and weightlifting ability: a field-test approach.

    Science.gov (United States)

    Carlock, Jon M; Smith, Sarah L; Hartman, Michael J; Morris, Robert T; Ciroslan, Dragomir A; Pierce, Kyle C; Newton, Robert U; Harman, Everett A; Sands, William A; Stone, Michael H

    2004-08-01

    The purpose of this study was to assess the usefulness of the vertical jump and estimated vertical-jump power as a field test for weightlifting. Estimated PP output from the vertical jump was correlated with lifting ability among 64 USA national-level weightlifters (junior and senior men and women). Vertical jump was measured using the Kinematic Measurement System, consisting of a switch mat interfaced with a laptop computer. Vertical jumps were measured using a hands-on-hips method. A counter-movement vertical jump (CMJ) and a static vertical jump (SJ, 90 degrees knee angle) were measured. Two trials were given for each condition. Test-retest reliability for jump height was intra-class correlation (ICC) = 0.98 (CMJ) and ICC = 0.96 (SJ). Athletes warmed up on their own for 2-3 minutes, followed by 2 practice jumps at each condition. Peak power (PP) was estimated using the equations developed by Sayers et al. (24). The athletes' current lifting capabilities were assessed by a questionnaire, and USA national coaches checked the listed values. Differences between groups (i.e., men versus women, juniors versus resident lifters) were determined using t-tests (p weightlifting ability. Thus, these results indicate that PP derived from the vertical jump (CMJ or SJ) can be a valuable tool in assessing weightlifting performance.

  3. Validation of the iPhone app using the force platform to estimate vertical jump height.

    Science.gov (United States)

    Carlos-Vivas, Jorge; Martin-Martinez, Juan P; Hernandez-Mocholi, Miguel A; Perez-Gomez, Jorge

    2018-03-01

    Vertical jump performance has been evaluated with several devices: force platforms, contact mats, Vertec, accelerometers, infrared cameras and high-velocity cameras; however, the force platform is considered the gold standard for measuring vertical jump height. The purpose of this study was to validate an iPhone app called My Jump, that measures vertical jump height by comparing it with other methods that use the force platform to estimate vertical jump height, namely, vertical velocity at take-off and time in the air. A total of 40 sport sciences students (age 21.4±1.9 years) completed five countermovement jumps (CMJs) over a force platform. Thus, 200 CMJ heights were evaluated from the vertical velocity at take-off and the time in the air using the force platform, and from the time in the air with the My Jump mobile application. The height obtained was compared using the intraclass correlation coefficient (ICC). Correlation between APP and force platform using the time in the air was perfect (ICC=1.000, P<0.001). Correlation between APP and force platform using the vertical velocity at take-off was also very high (ICC=0.996, P<0.001), with an error margin of 0.78%. Therefore, these results showed that application, My Jump, is an appropriate method to evaluate the vertical jump performance; however, vertical jump height is slightly overestimated compared with that of the force platform.

  4. Effects of a short proprioceptive neuromuscular facilitation stretching bout on quadriceps neuromuscular function, flexibility, and vertical jump performance.

    Science.gov (United States)

    Place, Nicolas; Blum, Yannick; Armand, Stéphane; Maffiuletti, Nicola A; Behm, David G

    2013-02-01

    The inclusion of relatively long bouts of stretching (repeated static stretches of ∼30 seconds) in the warm-up is usually associated with a drop in muscle performance. The purpose of this study was to assess the effect of a novel self-administered proprioceptive neuromuscular facilitation (PNF) paradigm with short periods of stretching and contraction on quadriceps neuromuscular function, vertical jump performance, and articular range of motion (ROM). Twelve healthy men (age: 27.7 ± 7.3 years, height: 178.4 ± 10.4 cm, weight: 73.8 ± 16.9 kg) volunteered to participate in a PNF session and a control session separated by 2-7 days. The PNF stretching lasted 2 minutes and consisted of 4 sets of 5-second isometric hamstring contraction immediately followed by 5 seconds of passive static stretch of the quadriceps immediately followed by 5 seconds isometric quadriceps contraction for each leg. For the control session, the participants were asked to walk at a comfortable speed for 2 minutes. Active ROM of knee flexion, vertical jump performance, and quadriceps neuromuscular function were tested before, immediately after, and 15 minutes after the intervention. The PNF stretching procedure did not affect ROM, squat jump, and countermovement jump performances. Accordingly, we did not observe any change in maximal voluntary contraction force, voluntary activation level, M-wave and twitch contractile properties that could be attributed to PNF stretching. The present self-administered PNF stretching of the quadriceps with short (5-second) stretches is not recommended before sports where flexibility is mandatory for performance.

  5. Minimizing Reanalysis Jumps Due to New Observing Systems

    Science.gov (United States)

    Zhou, Y.; Kalnay, E.; Chen, J.

    2014-12-01

    A major problem with reanalyses has been the presence of jumps in the climatology associated with changes in the observing system. These jumps became especially obvious when satellites were first introduced in 1979. After 1979, however, during the "satellite era" jumps have continued to appear whenever a new observing system was introduced. To explore this problem, we develop and test new methodologies to minimize these reanalysis jumps in the reanalyses time series due to new observing systems. We first study a state-of-the-art reanalysis, NASA's Modern Era Retrospective-analysis for Research and Applications (MERRA thereafter). Analysis increments from two 2-year analyses with SSM/I (referred to as MERRA) or without SSM/I (referred to as NoSSMI), are compared and their climatological differences are defined as correction terms. The correction terms are then introduced into the tendency equation of the forecast model, i.e., GEOS-5. The debiased reanalysis without SSM/I observations shows improvements in almost all fields, even in precipitation field that is generally considered to be uncertain on all time and space scales, but the correction is underestimated by about a factor of 2. We believe that this is because the correction terms defined here do not take into account the nonlinear interactions between the temperature and humidity fields observed by SSM/I, which would introduce accumulated errors during the 2-year experiment period. This deficiency can be corrected by doing the No-SSMI analysis using a MERRA background, as in the method of Danforth et al. (2007) We test the new correction method in a simpler data assimilation system, SPEEDY-LETKF because with our limited computational resource it is infeasible to apply this method to the complex MERRA system. The new method defines the correction terms by calculating the difference of analysis increments from the following two analyses, 1) assimilating both RAOB and AIRS observations, named RaobAirs, and 2

  6. Effects of the cycloergometer exercises on power and jumping ability measured during jumps performed on a dynamometric platform

    OpenAIRE

    A Mastalerz; A Madej; K Buśko

    2010-01-01

    The aim of this work was the determination of the cycloergometer exercises influence on the lower limbs power changes and height of rise of the body mass centre, measured in CMJ (counter movement jump) and performed on a dynamometric platform. Forty-three students of the University of Physical Education took part in the study. They were divided into 4 groups. The cycloergometer training encompassed 5 intermittent efforts parted by 2min intervals. Students performed: group M10 – maximal effort...

  7. Social Technologies to Jump Start Geoscience Careers

    Science.gov (United States)

    Keane, Christopher; Martinez, Cynthia; Gonzales, Leila

    2010-05-01

    early career geoscientists to tune in what's going on in the geoscience community, to meet geoscience professionals, and to find innovative career ideas. Early analysis of the page's participants indicates that the network is reaching its intended audience, with more than two-thirds of "fans" participating in the page falling in the 18-34 age range. Twenty-seven percent of these are college-aged, or 18-24 years old. An additional 20% of the page's fans are over age 45, providing students with access to seasoned geoscientists working in a variety of professions. GeoConnection's YouTube Channel includes video resources for students on educational pathways and career choices. Videos on the channel have received more than 100,000 views collectively. In addition, the AGI Workforce program has been an active participant in the YES network, and facilitated the virtual participation of both speakers and attendees for the first YES Congress, held in October 2009 in Beijing. By integrating webinar technologies and other social media, the breadth of attendees and speakers at the Congress was greatly expanded. Challenges with technology represented the minor problem for this effort, but rather human factors required the greatest focus to ensure success. Likewise, the challenge for the GeoConnection Network is not so much technology implementation, but rather remaining responsive and relevant with the ever-changing landscape of online communications. Reports show that participation in social-networking media among young people ages 16-24 has dropped (eg. Istrategy Labs, 2009, Ofcom, 2009) however, internet use among younger generations is high. Geoscience organizations must identify and participate in new online communications trends in order to continue to reach students and young professionals, but also, these individuals must also communicate with geosciences organizations so that the appropriate technologies and venues can be provided to strengthen the interconnect between

  8. Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads

    Directory of Open Access Journals (Sweden)

    Vanderka Marián, Longová Katarína, Olasz Dávid, Krčmár Matúš, Walker Simon

    2016-09-01

    Full Text Available The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax and rate of force development over 100ms (RFD100, countermovement jump (CMJ and squat jump (SJ height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg were divided into experimental (EXP; n = 36 and control (CON, n = 32 groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions. Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, p<0.001, and from mid- to post-training (Δ ~4%, p < 0.001 in EXP were observed. In CON significantly enhanced Fmax from pre- to mid-training (Δ ~3.5%, p < 0.05 was recorded, but no other significant changes were observed in any other test. In RFD100 significant improvements from pre- to mid-training (Δ ~27%, p < 0.001, as well as from mid- to post-training (Δ ~17%, p < 0.01 were observed. CMJ and SJ height were significantly enhanced from pre- to mid-training (Δ ~10%, ~15%, respectively, p < 0.001 but no further changes occurred from mid- to post-training. Significant improvements in 50 m sprint time from pre- to mid-training (Δ -1%, p < 0.05, and from mid- to post-training (Δ -1.9%, p < 0.001 in EXP were observed. Furthermore, percent changes in EXP were greater than changes in CON during training. It appears that using jump squats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term.

  9. Modeling and forecasting electricity price jumps in the Nord Pool power market

    DEFF Research Database (Denmark)

    Knapik, Oskar

    i) price drivers, ii) persistence, iii) seasonality of electricity prices. The models are shown to outperform commonly-used benchmark. The paper shows how crucial for price jumps forecasting is to incorporate additional knowledge on price drivers like loads, temperature and water reservoir level......For risk management traders in the electricity market are mainly interested in the risk of negative (drops) or of positive (spikes) price jumps, i.e. the sellers face the risk of negative price jumps while the buyers face the risk of positive price jumps. Understanding the mechanism that drive...... extreme prices and forecasting of the price jumps is crucial for risk management and market design. In this paper, we consider the problem of the impact of fundamental price drivers on forecasting of price jumps in NordPool intraday market. We develop categorical time series models which take into account...

  10. The effects of electromyostimulation training and basketball practice on muscle strength and jumping ability.

    Science.gov (United States)

    Maffiuletti, N A; Cometti, G; Amiridis, I G; Martin, A; Pousson, M; Chatard, J C

    2000-08-01

    The aim of this study was to investigate the influence of a 4-week electromyostimulation training program on the strength of the knee extensors and the vertical jump performance of 10 basketball players. Electromyostimulation sessions were carried out 3 times weekly; each session consisted of 48 contractions. Testing was carried out before and after the electromyostimulation training program (week 4) and once more after 4 weeks of normal basketball training (week 8). At week 4, isokinetic strength increased significantly (p training increased also isometric strength at the two angles adjacent to the training angle (p jump increased significantly by 14% at week 4 (p jump showed no change. At week 8, gains in isokinetic, isometric strength and squat-jump performance were maintained and the counter movement jump performance increased significantly by 17% (ptraining program enhanced knee extensor strength and squat jump performance of basketball players.

  11. Fuzzy Stochastic Optimal Guaranteed Cost Control of Bio-Economic Singular Markovian Jump Systems.

    Science.gov (United States)

    Li, Li; Zhang, Qingling; Zhu, Baoyan

    2015-11-01

    This paper establishes a bio-economic singular Markovian jump model by considering the price of the commodity as a Markov chain. The controller is designed for this system such that its biomass achieves the specified range with the least cost in a finite-time. Firstly, this system is described by Takagi-Sugeno fuzzy model. Secondly, a new design method of fuzzy state-feedback controllers is presented to ensure not only the regularity, nonimpulse, and stochastic singular finite-time boundedness of this kind of systems, but also an upper bound achieved for the cost function in the form of strict linear matrix inequalities. Finally, two examples including a practical example of eel seedling breeding are given to illustrate the merit and usability of the approach proposed in this paper.

  12. Water-Based Concurrent Training Improves Peak Oxygen Uptake, Rate of Force Development, Jump Height, and Neuromuscular Economy in Young Women.

    Science.gov (United States)

    Pinto, Stephanie S; Alberton, Cristine L; Cadore, Eduardo L; Zaffari, Paula; Baroni, Bruno M; Lanferdini, Fábio J; Radaelli, Régis; Pantoja, Patrícia D; Peyré-Tartaruga, Leonardo A; Wolf Schoenell, Maira C; Vaz, Marco A; Kruel, Luiz F M

    2015-07-01

    The study investigated the effects of different intrasession exercise sequences on the cardiorespiratory and neuromuscular adaptations induced by water-based concurrent training in young subjects. Twenty-six healthy young women (25.1 ± 2.9 years) were placed into 2 water-based concurrent training groups: resistance before (RA, n = 13) or after (AR, n = 13) aerobic training. Subjects trained resistance and aerobic training during 12 weeks, 2 times per week performing both exercise types in the same training session. Peak oxygen uptake (V[Combining Dot Above]O2peak), rate of force development (RFD) obtained during an isometric peak torque knee extension protocol, jump height, and neuromuscular economy (normalized electromyography at 80% of pretraining knee extension isometric peak torque) in young women were determined. After training, there was a significant increase (p training (RA: 19 vs. AR: 30%), and both groups presented similar gains. In addition, the countermovement jump height also increased (p = 0.034) after training (RA: 5% vs. AR: 6%), with no difference between groups. After training, there were significant improvements on vastus lateralis (p concurrent training improved the peak oxygen uptake, RFD, jump height, and neuromuscular economy in young women independent from the intrasession exercise sequence.

  13. Analytical solution to problems of hydraulic jump in horizontal triangular channels

    OpenAIRE

    I.M.H. Rashwan

    2013-01-01

    A hydraulic jump is formed in a channel whenever supercritical flow changes to subcritical flow in a short distance. It can be used in triangular ditch irrigation to raise the downstream water surface. The basic elements and characteristics of the hydraulic jump are provided to aid designers in selecting more practical basins. In the present study, the slope side, discharge and the energy loss in hydraulic jump in horizontal triangular section are known whereas one has to obtain the sequent d...

  14. Aerial Rotation Effects on Vertical Jump Performance Among Highly Skilled Collegiate Soccer Players.

    Science.gov (United States)

    Barker, Leland A; Harry, John R; Dufek, Janet S; Mercer, John A

    2017-04-01

    Barker, LA, Harry, JR, Dufek, JS, and Mercer, JA. Aerial rotation effects on vertical jump performance among highly skilled collegiate soccer players. J Strength Cond Res 31(4): 932-938, 2017-In soccer matches, jumps involving rotations occur when attempting to head the ball for a shot or pass from set pieces, such as corner kicks, goal kicks, and lob passes. However, the 3-dimensional ground reaction forces used to perform rotational jumping tasks are currently unknown. Therefore, the purpose of this study was to compare bilateral, 3-dimensional, and ground reaction forces of a standard countermovement jump (CMJ0) with those of a countermovement jump with a 180° rotation (CMJ180) among Division-1 soccer players. Twenty-four participants from the soccer team of the University of Nevada performed 3 trials of CMJ0 and CMJ180. Dependent variables included jump height, downward and upward phase times, vertical (Fz) peak force and net impulse relative to mass, and medial-lateral and anterior-posterior force couple values. Statistical significance was set a priori at α = 0.05. CMJ180 reduced jump height, increased the anterior-posterior force couple in the downward and upward phases, and increased upward peak Fz (p ≤ 0.05). All other variables were not significantly different between groups (p > 0.05). However, we did recognize that downward peak Fz trended lower in the CMJ0 condition (p = 0.059), and upward net impulse trended higher in the CMJ0 condition (p = 0.071). It was concluded that jump height was reduced during the rotational jumping task, and rotation occurred primarily via AP ground reaction forces through the entire countermovement jump. Coaches and athletes may consider additional rotational jumping in their training programs to mediate performance decrements during rotational jump tasks.

  15. Assesment of standing long jump at children of primery - school age in athletic prep school

    OpenAIRE

    Klapetková, Kristýna

    2017-01-01

    Title: Assesment of standing long jump at children of primery - school age in athletic prep school Aim: Aim of this thesis was to evaluate and compare differences of movement level in standing long jump between children of primary - school age who attend athletic prep school and those who don't. Another aim was the getting to know and the application of Haywood's and Getchell's methodology for qualitative assessment of standing long jump of children. Methodology: The movement level of standin...

  16. Jump Variation Estimation with Noisy High Frequency Financial Data via Wavelets

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2016-08-01

    Full Text Available This paper develops a method to improve the estimation of jump variation using high frequency data with the existence of market microstructure noises. Accurate estimation of jump variation is in high demand, as it is an important component of volatility in finance for portfolio allocation, derivative pricing and risk management. The method has a two-step procedure with detection and estimation. In Step 1, we detect the jump locations by performing wavelet transformation on the observed noisy price processes. Since wavelet coefficients are significantly larger at the jump locations than the others, we calibrate the wavelet coefficients through a threshold and declare jump points if the absolute wavelet coefficients exceed the threshold. In Step 2 we estimate the jump variation by averaging noisy price processes at each side of a declared jump point and then taking the difference between the two averages of the jump point. Specifically, for each jump location detected in Step 1, we get two averages from the observed noisy price processes, one before the detected jump location and one after it, and then take their difference to estimate the jump variation. Theoretically, we show that the two-step procedure based on average realized volatility processes can achieve a convergence rate close to O P ( n − 4 / 9 , which is better than the convergence rate O P ( n − 1 / 4 for the procedure based on the original noisy process, where n is the sample size. Numerically, the method based on average realized volatility processes indeed performs better than that based on the price processes. Empirically, we study the distribution of jump variation using Dow Jones Industrial Average stocks and compare the results using the original price process and the average realized volatility processes.

  17. Electromagnetic Transient Response Analysis of DFIG under Cascading Grid Faults Considering Phase Angel Jumps

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei

    2014-01-01

    This paper analysis the electromagnetic transient response characteristics of DFIG under symmetrical and asymmetrical cascading grid fault conditions considering phaseangel jump of grid. On deriving the dynamic equations of the DFIG with considering multiple constraints on balanced and unbalanced...... conditions, phase angel jumps, interval of cascading fault, electromagnetic transient characteristics, the principle of the DFIG response under cascading voltage fault can be extract. The influence of grid angel jump on the transient characteristic of DFIG is analyzed and electromagnetic response...

  18. USE OF WHOLE-BODY VIBRATION AS A MODE OF WARMING UP BEFORE COUNTER MOVEMENT JUMP

    Directory of Open Access Journals (Sweden)

    Enrique G. Artero

    2007-12-01

    Full Text Available Whole-body vibration (WBV has been suggested to be particularly effective on the stretch-shortening cycle-based movements, such as the counter movement jump (CMJ test (Issurin, 2005. Nevertheless, the literature on short-term vibration exposure and lower limb explosive performance (measured by CMJ test is contradictory. Either transient improvements (Bosco et al., 2000; Cochrane and Stannard, 2005; Torvinen et al., 2002a or no effects (Torvinen et al., 2002b; Rittweger et al., 2003; Cormie et al., 2006 have been reported after a single WBV exposure ranging from 30 s to 10 min. The present study aimed at better characterizing the use of a single short bout of WBV as a mode of warming up before a CMJ test.A total of 114 university students (37 men, 77 women, aged 19.6 ± 2.0 years signed an informed consent form and volunteered to participate in the study. The study protocol was approved by the Review Committee for Research Involving Human Subjects of our center. Participants were asked to come to the laboratory in three occasions three days apart. First visit: familiarization session aiming to learn the CMJ technique and to experience the vibration stimulus. Second visit: the participants performed three consecutive CMJ with one min rest interval. No significant differences were observed among the jumps, and the highest score was retained. Third visit: the participants were exposed to a single short bout of WBV and immediately after they performed three CMJ with one min rest interval.An infrared contact timing platform (ERGO JUMP Plus - BOSCO SYSTEM, Byomedic, S.C.P., Barcelona, Spain was used to measure "flight" time (t during the vertical jump (accuracy 0.001 s. Maximum height achieved by the body centre of gravity (h was then estimated, i.e. h = g · t2 / 8, where g = 9.81 m/s2. In all occasions, the participants were instructed to abstain from strenuous exercise for the preceding 24 hours.Whole-body vibration was carried out on an oscillating

  19. The effects of temperature and body mass on jump performance of the locust Locusta migratoria.

    Directory of Open Access Journals (Sweden)

    Edward P Snelling

    Full Text Available Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m scales with body mass (M; g according to the power equation D = 0.35M (0.17±0.08 (95% CI, jump take-off angle (A; degrees scales as A = 52.5M (0.00±0.06, and jump energy (E; mJ per jump scales as E = 1.91M (1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (L f+t; mm of the femur and tibia of the hind leg, L f+t = 34.9M (0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12% legs and a relatively larger (11% femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight.

  20. Triple-root jump in spacecraft potential due to electron beam emission or impact

    International Nuclear Information System (INIS)

    Lai, S.T.

    1992-01-01

    Triple-root jump in spacecraft potential is well understood in the double Maxwellian model of the natural space environment. In this paper, however, the author points out that triple-root jumps in spacecraft potential may also occur during photoemission or electron beam emission from a spacecraft. Impact of an incoming electron beam on a spacecraft may also cause triple-root jumps provided that the beam, ambient plasma, and surface parameters satisfy certain inequality conditions. The parametric conditions under which such beam induced triple-root jumps may occur are presented

  1. Validation of the VERT wearable jump monitor device in elite youth volleyball players

    Science.gov (United States)

    Borges, Thiago O.; Moreira, Alexandre; Bacchi, Renato; Finotti1, Ronaldo L.; Ramos, Mayara; Lopes, Charles R.

    2017-01-01

    This technical report aims to determine the validity and the accuracy of the VERT Wearable Jump Monitor. The participants of this study were all experienced volleyball players from the U18 category from the Brazilian National team. To assess jump performance, the VERT scores were compared to the VERTEC (jump and reach device). Each athlete performed 3 attack and 3 block jumps in a random, counterbalanced order, and the average score was registered. In the attack jumps, the VERTEC and VERT mean ± SD scores were 70.9±8.2 and 76.3±7.5 cm, respectively, and the typical error of the estimate (TEE) as a coefficient of variation (CV) was 7.8% (90% CL 7.0 to 8.9%). VERTEC and VERT devices presented a very large Pearson’s correlation for attack jumps (r=0.75; 90% CL 0.68 to 0.81). In addition, the mean±SD block jumps were 53.7±6.1 and 58.5±5.7 cm for the VERTEC and VERT, respectively and the TEE as a CV was 7.9% (90% CL 7.1 to 8.9%). Pearson’s correlation coefficient was very large for block jumps (r=0.75; 90% CL 0.67 to 0.81). The VERT device was found to be a very practical tool to quantify jump performance in volleyball players. PMID:29158616

  2. Application of a tri-axial accelerometer to estimate jump frequency in volleyball.

    Science.gov (United States)

    Jarning, Jon M; Mok, Kam-Ming; Hansen, Bjørge H; Bahr, Roald

    2015-03-01

    Patellar tendinopathy is prevalent among athletes, and most likely associated with a high jumping load. If methods for estimating jump frequency were available, this could potentially assist in understanding and preventing this condition. The objective of this study was to explore the possibility of using peak vertical acceleration (PVA) or peak resultant acceleration (PRA) measured by an accelerometer to estimate jump frequency. Twelve male elite volleyball players (22.5 ± 1.6 yrs) performed a training protocol consisting of seven typical motion patterns, including jumping and non-jumping movements. Accelerometer data from the trial were obtained using a tri-axial accelerometer. In addition, we collected video data from the trial. Jump-float serving and spike jumping could not be distinguished from non-jumping movements using differences in PVA or PRA. Furthermore, there were substantial inter-participant differences in both the PVA and the PRA within and across movement types (p volleyball. A method for acquiring real-time estimates of jump frequency remains to be verified. However, there are several alternative approaches, and further investigations are needed.

  3. The “Suicide Guard Rail”: a minimal structural intervention in hospitals reduces suicide jumps

    OpenAIRE

    Mohl, Andreas; Stulz, Niklaus; Martin, Andrea; Eigenmann, Franz; Hepp, Urs; Hüsler, Jürg; Beer, Jürg H

    2012-01-01

    Abstract Background Jumping from heights is a readily available and lethal method of suicide. This study examined the effectiveness of a minimal structural intervention in preventing suicide jumps at a Swiss general teaching hospital. Following a series of suicide jumps out of the hospital’s windows, a metal guard rail was installed at each window of the high-rise building. Results In the 114 months prior to the installation of the metal guard rail, 10 suicides by jumping out of the hospital’...

  4. Validity and reliability of Optojump photoelectric cells for estimating vertical jump height.

    Science.gov (United States)

    Glatthorn, Julia F; Gouge, Sylvain; Nussbaumer, Silvio; Stauffacher, Simone; Impellizzeri, Franco M; Maffiuletti, Nicola A

    2011-02-01

    Vertical jump is one of the most prevalent acts performed in several sport activities. It is therefore important to ensure that the measurements of vertical jump height made as a part of research or athlete support work have adequate validity and reliability. The aim of this study was to evaluate concurrent validity and reliability of the Optojump photocell system (Microgate, Bolzano, Italy) with force plate measurements for estimating vertical jump height. Twenty subjects were asked to perform maximal squat jumps and countermovement jumps, and flight time-derived jump heights obtained by the force plate were compared with those provided by Optojump, to examine its concurrent (criterion-related) validity (study 1). Twenty other subjects completed the same jump series on 2 different occasions (separated by 1 week), and jump heights of session 1 were compared with session 2, to investigate test-retest reliability of the Optojump system (study 2). Intraclass correlation coefficients (ICCs) for validity were very high (0.997-0.998), even if a systematic difference was consistently observed between force plate and Optojump (-1.06 cm; p photoelectric cells is legitimate for field-based assessments of vertical jump height.

  5. Impact of the focus of attention on vertical jump performance of junior basketball players

    Directory of Open Access Journals (Sweden)

    Manojlović Vladimir

    2013-01-01

    Full Text Available The aim of the research was to determine the impact of the focus of attention on vertical jump performance expressed through a jump height. Thirteen basketball players (body mass = 73,4 kg, height = 186,58 cm, age = 15.12 ± 0.61 y volunteered as participants. All the subject represented a club which participated in the Croatian cadets 1. league in season 2008/09, and were tested during the season. The subjects performed two experiments. In both experiments, they performed 15 repetitions of countermovement jump, whereas in one of the experiments, during the performance of the jumps they were listening to an audio record of spectators. For both type of jumps, the subjects were instructed to stay in the air as long as possible during a single jump (external focus of attention. To determine the differences between jumps, a paired-sample t-test was used with a level of statistical significance set to p ≤ 0.05. Comparison for jump height between both type of jumps revealed no statistically significant difference, although the presented difference should not be denied considering a real match conditions.

  6. Stationary distribution and ergodicity of a stochastic food-chain model with Lévy jumps

    Science.gov (United States)

    Yu, Jingyi; Liu, Meng

    2017-09-01

    In this paper, a three-species stochastic food-chain model with Lévy jumps is proposed and analyzed. Sharp sufficient criteria for the existence and uniqueness of an ergodic stationary distribution are established. The effects of Lévy jumps on the existence of the stationary distribution are revealed: in some cases, the Lévy jumps could make the stationary distribution appear, while in some cases, the Lévy jumps could make the stationary distribution disappear. Some numerical simulations are introduced to illustrate the theoretical results.

  7. Comparison between vertical jumps of high performance athletes on the Brazilian men's beach volleyball team.

    Science.gov (United States)

    Ricarte Batista, G; Freire De Araújo, R; Oliveira Guerra, R

    2008-06-01

    The aim of this paper was to compare the anthropometric profile and the vertical jumps of two groups of Brazilian male high performance beach volleyball players. The sample consisted of 38 male beach volleyball players from the Brazilian Beach Volleyball Circuit of 2006, allocated to two groups according to national ranking of their teams. Anthropometric measures and performance in vertical jumps were assessed using a specific methodology. The anthropometric results of the groups showed no statistically significant differences. The players of group 1 (G1) were better in the spike jump (P<0.01), block jump (P<0.01) and block difference (P<0.01) than the players of group 2 (G2). The prediction model of the spike jump for G2 included body mass and standing spike reach (adjusted R2=0.77) while for the block jump model it was body mass and standing block reach (adjusted R2=0.73). The regression models for G1 were not statistically significant. It is likely that vertical jump height (spike and block) influences the performance of beach volleyball players, and consequently the performance of their teams, since the present study found higher values in G1 than in G2 for the spike jump, block jump and block difference. However, an athlete's success is not related only to the variables investigated in this study; technical skill, tactics, psychology and physical conditioning can also play a role.

  8. Assessment of musculoskeletal system in women with jumping mechanography

    Directory of Open Access Journals (Sweden)

    Yannis Dionyssiotis

    2009-08-01

    Full Text Available Yannis Dionyssiotis1,2, Antonios Galanos1, Georgios Michas1, Georgios Trovas1, Georgios P Lyritis11Laboratory for Research of the Musculoskeletal System, University of Athens, KAT Hospital, Kifissia, Greece; 2Rehabilitation Department, Rhodes General Hospital, Rhodes, GreeceAbstract: The purpose of this study was to investigate and add reference data about the musculoskeletal system in women. The mechanography system of the Leonardo™ platform (Novotec, Germany was used to measure parameters of movement (velocity, force, power in 176 healthy Greek women aged 20–79 years, separated according to age decade in six groups: group 1 (n = 12, 20–29 years; group 2 (n = 14, 30–39 years; group 3 (n = 33, 40–49 years; group 4 (n = 59, 50–59 years including 21 postmenopausal; group 5 (n = 31, 60–69 years including 12 postmenopausal; and group 6 (n = 27, 70–79 years all postmenopausal. This system measures forces applied to the plate over time, calculates through acceleration the vertical velocity of center of gravity and using force and velocity it calculates power of vertical movements. All women performed a counter-movement jump (brief squat before the jump with freely moving arms. Weight was recorded on the platform before the jump and height was measured with a wall-mounted ruler. Body weight and body mass index were gradually increased; on the contrary height and all movement parameters except force (velocity, power were statistically decreased during aging and after menopause.Keywords: biomechanics, ground reaction force, power, women, menopause

  9. Respostas neuromusculares dos membros inferiores durante protocolo intermitente de saltos verticais em voleibolistas Neuromuscular responses of the lower limb muscles during vertical jumping in volleyball athletes

    Directory of Open Access Journals (Sweden)

    Caroline Tosini Felicissimo

    2012-03-01

    Full Text Available O objetivo deste estudo foi analisar o desempenho e as respostas eletromiográficas dos músculos Reto Femoral, Bíceps Femoral e Gastrocnêmio Medial durante protocolo de saltos verticais. Participaram 13 voleibolistas do sexo feminino (15,6 ± 0,9 anos. Inicialmente foi realizado um protocolo de potência máxima (três saltos máximos, seguido do protocolo de resistência de saltos (ciclos de três saltos máximos em aproximadamente 10 segundos (s - um salto a cada três s, com recuperação de 15 s. O tempo de duração do protocolo de resistência foi de 20 minutos. Foi usada a técnica do salto com contramovimento sem ajuda dos braços, sobre tapete de contato. Para tratamento dos dados os saltos foram divididos em quatro períodos com 12 ciclos cada um. Os resultados mostraram queda na altura dos saltos de aproximadamente 1,3cm entre os períodos de 1 a 4, sendo que, essa queda foi mais significativa nos 3º e 4º períodos em comparação ao 1º e 2º. Entretanto, com relação às variáveis RMS e FM, não ocorreu alteração nas respostas eletromiográficas entre músculos e períodos. Concluiu-se, assim, que a fadiga pode depender de variáveis psicofisiológicas, ao nível do SNC, que também influem no desempenho.The purpose of this study was to analyze the performance and the electromyographic responses of the muscles Rectus Femoris, Biceps Femoris and Gastrocnemius Medialis during vertical jumping protocol. Participated 13 female volleyball players (15,6 ± 0,9 years. Initially was performed a protocol of maximum power (three maximum jumps, followed by resistance jumps protocol (cycles of three maximum jumps in about 10 seconds (s - one jump every three s, with recovery of 15s. The duration of resistance protocol was 20 minutes. Technique used was countermovement jump without the aid of arms on a mat of contact. The data collected during the jumps were divided into four periods containing 12 cycles each. The results showed a

  10. Kinetic asymmetries between forward and drop jump landing tasks

    OpenAIRE

    Morgana Alves de Britto; Pedro Silvelo Franco; Evangelos Pappas; Felipe P Carpes

    2015-01-01

    DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n6p661   Landing asymmetry is a risk factor for knee anterior cruciate ligament injury. The aim of this study was to identify kinetic asymmetries in healthy recreational athletes performing different jump-landing techniques. Twelve recreational athletes engaged in regular training underwent kinetic evaluation using two 3D force plates and were analyzed for: (a) three-dimensional peak forces, (b) time to peak vertical force, and (c) initi...

  11. European option pricing under the Student's t noise with jumps

    Science.gov (United States)

    Wang, Xiao-Tian; Li, Zhe; Zhuang, Le

    2017-03-01

    In this paper we present a new approach to price European options under the Student's t noise with jumps. Through the conditional delta hedging strategy and the minimal mean-square-error hedging, a closed-form solution of the European option value is obtained under the incomplete information case. In particular, we propose a Value-at-Risk-type procedure to estimate the volatility parameter σ such that the pricing error is in accord with the risk preferences of investors. In addition, the numerical results of us show that options are not priced in some cases in an incomplete information market.

  12. Biomechanics of optimal flight in ski-jumping.

    Science.gov (United States)

    Remizov, L P

    1984-01-01

    The flight in a vertical plane of a ski-jumper after take-off was studied with the purpose of maximising flight distance. To solve the problem of optimal flight (how a jumper must change his angle of attack to obtain the longest jump) the basic theorem of the optimal control theory--Pontriagin's maximum principle--was applied. The calculations were based on data from wind tunnel experiments. It was shown that the maximum flight distance is achieved when the angle of attack is gradually increased according to a convex function the form of which depends on the individual aerodynamic parameters.

  13. The SAMBA quick-EXAFS monochromator: XAS with edge jumping.

    Science.gov (United States)

    Fonda, E; Rochet, A; Ribbens, M; Barthe, L; Belin, S; Briois, V

    2012-05-01

    Results and performances of the QEXAFS double monochromator of the SAMBA beamline (Synchrotron SOLEIL) are presented. The device is capable of speeds of up to 40 Hz, while giving the user the possibility to choose the amplitude of the scan from 0.1° to 4° in a few seconds. The device is composed of two independent units and it is possible to perform scans alternating between two different crystals, literally jumping from low (4 keV) to high (37 keV) energies.

  14. Analysis and design of singular Markovian jump systems

    CERN Document Server

    Wang, Guoliang; Yan, Xinggang

    2014-01-01

    This monograph is an up-to-date presentation of the analysis and design of singular Markovian jump systems (SMJSs) in which the transition rate matrix of the underlying systems is generally uncertain, partially unknown and designed. The problems addressed include stability, stabilization, H∞ control and filtering, observer design, and adaptive control. applications of Markov process are investigated by using Lyapunov theory, linear matrix inequalities (LMIs), S-procedure and the stochastic Barbalat's Lemma, among other techniques.Features of the book include:·???????? study of the stability pr

  15. Jump conditions for thin bodies from an action principle

    Science.gov (United States)

    Hanna, James

    2015-03-01

    Thin, flexible bodies such as strings, sheets, and rods often sustain kinky geometric features, or experience discontinuous contact forces in their interactions with obstacles. The physics of dynamic and static versions of these phenomena differ. Kink/shock propagation, impact, peeling, unwrapping, tearing and cracking all occur at geometric locations in a body that do not correspond to material points. I will discuss how the jump conditions for momentum and energy across such moving discontinuities may be derived from an action principle for an extended body with time-dependent, non-material boundaries.

  16. Multiscale integration schemes for jump-diffusion systems

    Energy Technology Data Exchange (ETDEWEB)

    Givon, D.; Kevrekidis, I.G.

    2008-12-09

    We study a two-time-scale system of jump-diffusion stochastic differential equations. We analyze a class of multiscale integration methods for these systems, which, in the spirit of [1], consist of a hybridization between a standard solver for the slow components and short runs for the fast dynamics, which are used to estimate the effect that the fast components have on the slow ones. We obtain explicit bounds for the discrepancy between the results of the multiscale integration method and the slow components of the original system.

  17. Changes in ground reaction force during a rebound-jump task after hip strength training for single-sided ankle dorsiflexion restriction.

    Science.gov (United States)

    Kondo, Hitoshi; Someya, Fujiko

    2016-01-01

    [Purpose] Lateral ankle sprains are common injuries suffered while playing sports, and abnormal forward- and inward-directed ground reaction force occurs during a jumping task. However, the influence of hip muscle strength training on jumping performance after ankle injuries has not been fully examined. This study thus examined changes in ground reaction force during a rebound-jump task after training to strengthen hip muscles. [Subjects and Methods] Ten of 30 female high school basketball players were assigned as subjects who showed a difference of 7 or more degrees in dorsiflexion ranges between the bilateral ankles. The subjects underwent 12 weeks of training to strengthen hip abductors and external rotators. Comparisons between before and after training were made regarding ground reaction force components, hip and knee joint angles, percentage of maximum voluntary contraction in leg muscles, and muscle strength of hip muscles during the rebound-jump task. [Results] After training, the subjects showed increased strength of external rotator muscles, increased percentage of maximum voluntary contraction in the gluteus medius muscle, decreased inward ground reaction force, and increased flexion angles of the hip and knee joints. [Conclusion] This study suggests that training to strengthen hip muscles may ameliorate the inward ground reaction force in athletes with ankle dorsiflexion restriction.

  18. Optimizing Half Squat Postactivation Potential Load in Squat Jump Training for Eliciting Relative Maximal Power in Ski Jumpers.

    Science.gov (United States)

    Gołaś, Artur; Wilk, Michal; Stastny, Petr; Maszczyk, Adam; Pajerska, Katarzyna; Zając, Adam

    2017-11-01

    Gołaś, A, Wilk, M, Stastny, P, Maszczyk, A, Pajerska, K, and Zając, A. Optimizing half squat postactivation potential load in squat jump training for eliciting relative maximal power in ski jumpers. J Strength Cond Res 31(11): 3010-3017, 2017-Training load manipulation in a single workout session can increase or decrease training effectiveness in terms of athletes' strength or power gains. In ski jumping, the complex training that elicits maximal power gains may take advantage of the postactivation potentiation (PAP) mechanism. The aim of this research was to evaluate the changes in rate of force development (RFD), rate of power development (RPD), and jump height during a complex training session consisted of the barbell half squat (Sq) as a conditioning exercise with loads ranged between 60 and 100% of 1 repetition maximum (1RM), followed by a body weight squat jump (SqJ) as a performance task. The study was conducted with 16 elite athletes from the Polish National Ski Jumping Team, age 23 ± 8 years, body mass 56 ± 9 kg, and height 172 ± 12 cm. Complex training session started with the Sq at 60% of 1RM as the conditioning exercise, followed by 3 minutes of rest and the SqJ. The conditioning barbell half Sq was performed with 70, 80, 90, and 100% of 1RM with 5 minutes of rest. The differences in RFD occurred between an SqJ following the application of 80% of 1RM and all other SqJs (p = 0.01), and in RPD between SqJ without conditioning, SqJ after 60% of 1RM and 80% of 1RM (p = 0.02). On average, the most effective load in inducing PAP during ski jumpers' SqJ training is 80% of 1RM. The intensity of the conditioning exercise that elicits the greatest PAP effect should be individualized (60-100% 1RM), as it is dependent on the level of maximal strength.

  19. Permeability and stress-jump effects on magnetic drug targeting in a permeable microvessel using Darcy model

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, S., E-mail: sachinshaw@gmail.com [Department of Mathematics and Statistical Sciences, Botswana International University of Science and Technology, Private Bag 16, Palapye (Botswana); Sutradhar, A.; Murthy, PVSN [Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal (India)

    2017-05-01

    In the present paper, we investigated the influence of permeability of the carrier particle and stress jump condition on the porous spherical surface in magnetic drug targeting through a permeable microvessel. The nature of blood is defined by non-Newtonian Casson fluid in the core region of the microvessel and Newtonian fluid in the peripheral region which is located near the surface of the wall of the microvessel. The magnetic particles are considered as spherical and in nanosize, embedded in the carrier particle along with drug particles. A magnet is placed near the tumor position to generate a magnetic field. The relative motion of the carrier particle is the resultant of the fluidic force, magnetic force and Saffman drag force which are calculated for the spherical carrier particle. Trajectories of the carrier particle along the radial and axial direction are calculated. Effect of different parameters such as stress-jump constant, permeability of the carrier particle, pressure gradient, yield stress, Saffman force, volume fraction of the embedded magnetic nanoparticles, permeability of the microvessel wall, and the radius of the carrier particle on the trajectory of the carrier particle are discussed and displayed graphically. - Highlights: • In the present manuscript, we considered the porous carrier particle which provide a larger surface area contact with the fluid than the solid spherical carrier particle. It shows that the porous carrier particle are captured easily than the solid carrier particle. • Introduce Suffman force on the carrier particle which commences an additional resistance which acts opposite to the surface wall and helps the particles to go away from the tumor position. • Considered stress jump condition at the surface of the porous carrier particle which enhanced the tendency of the carrier particle to be capture near the tumor. • Used Darcy model to define the permeability of the wall of the microvessel.

  20. Age-associated power decline from running, jumping, and throwing male masters world records.

    Science.gov (United States)

    Gava, Paolo; Kern, Helmut; Carraro, Ugo

    2015-01-01

    BACKGROUND/STUDY CONTEXT: The capacity to perform everyday tasks is directly related to the muscular power the body can develop (see Appendix). The age-related loss of power is a fact, but the characterization or the rate of muscle power loss remains an open issue. Data useful to study the decline of the skeletal muscles power are largely available from sources other than medical tests, e.g., from track and field competitions of Masters athletes. The aim of our study is to identify the age-related decline trend of the power developed by the athletes in carrying out the track and field events. Absolute male world records of 16 events were collected along with world records of male Masters categories. Performance was normalized with respect to the absolute record; the performance of various age groups is consequently represented by a number ranging from 1 (world absolute records) to 0 (null performance). The performance of a jumping event is transformed into a parameter proportional to the power developed by the athletes: the displacement of the center of gravity of the athlete. Throwing events are further normalized for the decreasing weight of the implements with the increasing age of the Masters athletes. Most track and field events show a linear decline to 70 years. The annual rate of power decline for all the events (running, throwing, and jumping), using a simplified synthesis, is 1.25% per year. The events that involve mostly upper limbs (shot put, javelin throw) show a higher rate of decline (1.4% per year) compared to those where the lower limbs are mostly involved (long jump 1.1%, track events 0.6-0.7% per year). This analysis of muscle power decline is only partially in line with the results of works based on clinical tests. A clarification of the reasons for such discrepancy may provide clinically significant information. Human power decline in Masters athletes was analyzed, adopting a coherent approach based on an extended database. Skeletal muscle power

  1. Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads

    Science.gov (United States)

    Marián, Vanderka; Katarína, Longová; Dávid, Olasz; Matúš, Krčmár; Simon, Walker

    2016-01-01

    The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions). Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, p<0.001), and from mid- to post-training (Δ ~4%, p < 0.001) in EXP were observed. In CON significantly enhanced Fmax from pre- to mid-training (Δ ~3.5%, p < 0.05) was recorded, but no other significant changes were observed in any other test. In RFD100 significant improvements from pre- to mid-training (Δ ~27%, p < 0.001), as well as from mid- to post-training (Δ ~17%, p < 0.01) were observed. CMJ and SJ height were significantly enhanced from pre- to mid-training (Δ ~10%, ~15%, respectively, p < 0.001) but no further changes occurred from mid- to post-training. Significant improvements in 50 m sprint time from pre- to mid-training (Δ -1%, p < 0.05), and from mid- to post-training (Δ -1.9%, p < 0.001) in EXP were observed. Furthermore, percent changes in EXP were greater than changes in CON during training. It appears that using jump squats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term. Key points Jump squat exercise is one of many exercises to develop explosive strength

  2. Alterações oculares associadas ao "bungee jumping": relato de caso Ocular alterations associated with bungee jumping: case report

    Directory of Open Access Journals (Sweden)

    José Ricardo Diniz

    2005-12-01

    Full Text Available Com a popularização do "bungee jumping" vem se observando aumento na ocorrência de lesões associadas a sua prática, entre elas lesões oculares. O objetivo deste relato é descrever um caso de diminuição aguda da acuidade visual e alterações campimétricas após "bungee jumping". Os autores apresentam o caso de paciente de sexo feminino, 48 anos, sem história de doença ocular ou sistêmica, que chega a consulta em emergência oftalmológica com queixa de baixa da acuidade visual após "bungee jumping", apresentando ao exame oftalmológico inicial, hemorragias em pólo posterior de ambos os olhos. A angiografia fluoresceínica apresentava áreas hipofluorescentes, por bloqueio do contraste, correspondendo às hemorragias, sem outras alterações vasculares. Avaliada após 14 semanas, observou-se reabsorção das hemorragias e rarefação do epitélio pigmentar da retina em pólo posterior; evoluiu clinicamente com melhora da visão, mas permaneceu com queixa de escotoma e alterações campimétricas mesmo cinco meses após o evento inicial. A ocorrência de lesões corporais, entre elas lesões oculares, com risco de diminuição da acuidade visual deve ser informada aos candidatos à prática deste esporte, sendo papel do oftalmologista prover informações à população em geral sobre possíveis afecções oculares, neste esporte e no cotidiano.The popularization of bungee jumping is causing an increase in occurrences of lesions associated with its practice, including ocular lesions. The purpose of this study is to describe a case of acute decrease in vision and visual field defects following a bungee jump. The authors present a case of a 48-year-old woman, without history of systemic or ocular disorders, seen at an ophthalmologic emergency service with visual loss complaint following a bungee jump. On initial ophthalmologic evaluation, hemorrhages in the posterior pole of both eyes were found. Fluorescein angiography showed

  3. MUSCLE STRENGTH AND QUALITATIVE JUMP-LANDING DIFFERENCES IN MALE AND FEMALE MILITARY CADETS: THE JUMP-ACL STUDY

    Directory of Open Access Journals (Sweden)

    Barry P. Boden

    2009-12-01

    Full Text Available Recent studies have focused on gender differences in movement patterns as risk factors for ACL injury. Understanding intrinsic and extrinsic factors which contribute to movement patterns is critical to ACL injury prevention efforts. Isometric lower- extremity muscular strength, anthropometrics, and jump-landing technique were analyzed for 2,753 cadets (1,046 female, 1,707 male from the U.S. Air Force, Military and Naval Academies. Jump- landings were evaluated using the Landing Error Scoring System (LESS, a valid qualitative movement screening tool. We hypothesized that distinct anthropometric factors (Q-angle, navicular drop, bodyweight and muscle strength would predict poor jump-landing technique in males versus females, and that female cadets would have higher scores (more errors on a qualitative movement screen (LESS than males. Mean LESS scores were significantly higher in female (5.34 ± 1.51 versus male (4.65 ± 1.69 cadets (p < 0.001. Qualitative movement scores were analyzed using factor analyses, yielding five factors, or "patterns", contributing to poor landing technique. Females were significantly more likely to have poor technique due to landing with less hip and knee flexion at initial contact (p < 0.001, more knee valgus with wider landing stance (p < 0. 001, and less flexion displacement over the entire landing (p < 0.001. Males were more likely to have poor technique due to landing toe-out (p < 0.001, with heels first, and with an asymmetric foot landing (p < 0.001. Many of the identified factor patterns have been previously proposed to contribute to ACL injury risk. However, univariate and multivariate analyses of muscular strength and anthropometric factors did not strongly predict LESS scores for either gender, suggesting that changing an athlete's alignment, BMI, or muscle strength may not directly improve his or her movement patterns

  4. The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps.

    Science.gov (United States)

    Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

    2014-09-01

    The purposes of this study were to test the reproducibility of the 2.5-minute loaded repeated jump test (LRJT) and to test the effectiveness of general preparation period (GPP) training on anaerobic fitness of elite alpine ski racers with the LRJT. Thirteen male volunteers completed 2 LRJTs to examine reliability. Nine male Austrian elite junior racers were tested in June and October 2009. The LRJT consisted of 60 loaded countermovement jumps (LCMJs) with a loaded barbell equivalent to 40% bodyweight. Before the LRJT, the power (P) of a single LCMJ was determined. Power was calculated from ground reaction forces. The mean P was calculated for the complete test and for each 30-second interval. The interclass correlation coefficients (between 0.88 and 0.99) for main variables of the LRJT demonstrated a high reliability. A repeated-measures analysis of variance indicated that anaerobic capacity was significantly higher in October (p ≤ 0.05). The ski racers' single LCMJ P increased from 37.0 ± 1.2 W·kg to 39.0 ± 1.4 W·kg. The mean P of the total test improved from 33.6 ± 1.2 W·kg to 35.8 ± 1.3 W·kg, but relative effect of fatigue did not change. The GPP training improved the athletes' ability to produce and maintain muscular power. The LRJT is a reliable anaerobic test suitable for all alpine ski racing events because the 60 jumps simulate the approximate number of gates in slalom and giant slalom races and the 2.5 minutes is equivalent to the duration of the longest downhill race.

  5. Effects of the cycloergometer exercises on power and jumping ability measured during jumps performed on a dynamometric platform

    Directory of Open Access Journals (Sweden)

    A Mastalerz

    2010-03-01

    Full Text Available The aim of this work was the determination of the cycloergometer exercises influence on the lower limbs power changes and height of rise of the body mass centre, measured in CMJ (counter movement jump and performed on a dynamometric platform. Forty-three students of the University of Physical Education took part in the study. They were divided into 4 groups. The cycloergometer training encompassed 5 intermittent efforts parted by 2min intervals. Students performed: group M10 – maximal efforts with the load equal 10% of body mass; group M5 – maximal efforts with the load of 5% body mass; group W80 – 3min efforts with the power of 250 W, singular effort work equal 45 kJ, pedalling rate – 80 rpm; group W45 – 3min efforts with the power of 250 W, individual effort work equal 45 kJ, pedalling rate of 45 rpm. The control measurements of lower extremities power and the height of rise of the body mass centre in CMJ jumps on the dynamometric platform, were taken every Monday: before training (0, during 4 weeks of training (1-4 and for 2 weeks after it (5-6. Four week training elicited in groups M10, M5, W45 and W45 significant increase of the maximal (except group W45 where it was unimportant and average power and, decrease of the height of the body mass centre lift in CMJ jump: crucial in groups W45 (-4.7% and W80 (-4.7% and not important in M10 (-3.4% The height of rise of the body mass centre insignificant increase in group M5 (2.1% after 4 week training.

  6. Ballistic stretching increases flexibility and acute vertical jump height when combined with basketball activity.

    Science.gov (United States)

    Woolstenhulme, Mandy T; Griffiths, Christine M; Woolstenhulme, Emily M; Parcell, Allen C

    2006-11-01

    Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week -1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p basketball play, as it is beneficial to vertical jump performance.

  7. Effects of a Low-Load Gluteal Warm-Up on Explosive Jump Performance

    Directory of Open Access Journals (Sweden)

    Comyns Thomas

    2015-06-01

    Full Text Available The purpose of this study was to investigate the effects of a low-load gluteal warm-up protocol on countermovement and squat jump performance. Research by Crow et al. (2012 found that a low-load gluteal warm-up could be effective in enhancing peak power output during a countermovement jump. Eleven subjects performed countermovement and squat jumps before and after the gluteal warm-up protocol. Both jumps were examined in separate testing sessions and performed 30 seconds, and 2, 4, 6 & 8 minutes post warm-up. Height jumped and peak ground reaction force were the dependent variables examined in both jumps, with 6 additional variables related to fast force production being examined in the squat jump only. All jumps were performed on a force platform (AMTI OR6-5. Repeated measures analysis of variance found a number of significant differences (p ≤ 0.05 between baseline and post warm-up scores. Height jumped decreased significantly in both jumps at all rest intervals excluding 8 minutes. Improvement was seen in 7 of the 8 recorded SJ variables at the 8 minute interval. Five of these improvements were deemed statistically significant, namely time to peak GRF (43.0%, and time to the maximum rate of force development (65.7% significantly decreased, while starting strength (63.4%, change of force in first 100 ms of contraction (49.1% and speed strength (43.6% significantly increased. The results indicate that a gluteal warm-up can enhance force production in squat jumps performed after 8 minutes recovery. Future research in this area should include additional warm-up intervention groups for comparative reasons.

  8. The effects of resistance training on explosive strength indicators in adolescent basketball players.

    Science.gov (United States)

    Santos, Eduardo J A M; Janeira, Manuel A A S

    2012-10-01

    The purpose of this study was to assess the effects of a lower- and upper-body 10-week in-season resistance training program on explosive strength development in young basketball players. Twenty-five adolescent male athletes, aged 14-15 years old, were randomly assigned to an experimental group (EG; n = 15) and a control group (CG; n = 10). The subjects were assessed at baseline and after training for squat jump (SJ), countermovement jump (CMJ), Abalakov test, drop jump, and seated medicine ball throw (MBT). The EG showed significant increases (p training program with moderate volume and intensity loads increased vertical jump and MBT performance in adolescent male basketball players. Coaches should know that such a short resistance training program specifically designed for young basketball players induce increased explosivity levels, which are essential to a better basketball performance, with no extra overload on adolescents' skeletal muscle development.

  9. Tunneling of the blocked wave in a circular hydraulic jump

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Jayanta K., E-mail: jkb@hri.res.in

    2017-02-19

    The formation of a circular hydraulic jump in a thin liquid layer involves the creation of a horizon where the incoming wave (surface ripples) is blocked by the fast flowing fluid. That there is a jump at the horizon is due to the viscosity of the fluid which is not relevant for the horizon formation. By using a tunneling formalism developed for the study of the Hawking radiation from black holes, we explicitly show that there will be an exponentially small tunneling of the blocked wave across the horizons as anticipated in studies of “analog gravity”. - Highlights: • A thin layer of radially flowing fluid traveling at high speed sweeps away the incoming ripples. • The speed decreases as the flow spreads out. • At some radius the flow speed decreases to match the ripple speed creating a “horizon”. • The “horizon” blocks out the incoming ripples mimicking a white hole horizon. • The fluctuations around the steady state allows an exponentially small penetration inside the horizon analogous to the Hawking effect.

  10. Aerodynamics of ski jumping flight and its control: I. Experiments

    Science.gov (United States)

    Jung, Daehan; Bang, Kyeongtae; Kim, Heesu; Ahn, Eunhye; Choi, Haecheon

    2015-11-01

    In a ski jumping competition, it is essential to analyze the effect of various posture parameters of a ski jumper to achieve a longer flight distance. For this purpose, we construct a model of a ski jumper by using three-dimensional surface data obtained by scanning a ski jumper's body (Mr. Chil-Ku Kang, member of the Korean national team). An experiment on this model is conducted in a wind tunnel. We consider four posture parameters (forward leaning angle, ski opening angle, ski rolling angle, and ski spacing) and measure the drag and lift forces for various flight postures at various angles of attack (α = 0° - 40°) and Reynolds numbers (Re = 5.4 × 105 - 1.6 × 106) based on the length of the jump ski. Then, we derive optimum values of posture parameters for maximum lift-to-drag ratio using a response surface method. We also conduct a full-scale wind tunnel experiment with members of the Korean national team and confirm the results obtained from the experiment on the model. Supported by the NRF program (2014M3C1B1033848).

  11. Quantum jump from singularity to outside of black hole

    Energy Technology Data Exchange (ETDEWEB)

    Dündar, Furkan Semih [Physics and Mathematics Departments, Sakarya University, 54050, Sakarya (Turkey); Hajian, Kamal [School of Physics, Institute for Research in Fundamental Sciences, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11365-8639, Tehran (Iran, Islamic Republic of)

    2016-02-26

    Considering the role of black hole singularity in quantum evolution, a resolution to the firewall paradox is presented. It is emphasized that if an observer has the singularity as a part of his spacetime, then the semi-classical evolution would be non-unitary as viewed by him. Specifically, a free-falling observer inside the black hole would have a Hilbert space with non-unitary evolution; a quantum jump for particles encountering the singularity to outside of the horizon as late Hawking radiations. The non-unitarity in the jump resembles the one in collapse of wave function, but preserves entanglements. Accordingly, we elaborate the first postulate of black hole complementarity: freely falling observers who pass through the event horizon would have non-unitary evolution, while it does not have physically measurable effects for them. Besides, no information would be lost in the singularity. Taking the modified picture into account, the firewall paradox can be resolved, respecting No Drama. A by-product of our modification is that roughly half of the entropy of the black hole is released close to the end of evaporation in the shape of very hot Hawking radiation.

  12. Markov Jump Processes Approximating a Non-Symmetric Generalized Diffusion

    International Nuclear Information System (INIS)

    Limić, Nedžad

    2011-01-01

    Consider a non-symmetric generalized diffusion X(⋅) in ℝ d determined by the differential operator A(x) = -Σ ij ∂ i a ij (x)∂ j + Σ i b i (x)∂ i . In this paper the diffusion process is approximated by Markov jump processes X n (⋅), in homogeneous and isotropic grids G n ⊂ℝ d , which converge in distribution in the Skorokhod space D([0,∞),ℝ d ) to the diffusion X(⋅). The generators of X n (⋅) are constructed explicitly. Due to the homogeneity and isotropy of grids, the proposed method for d≥3 can be applied to processes for which the diffusion tensor {a ij (x)} 11 dd fulfills an additional condition. The proposed construction offers a simple method for simulation of sample paths of non-symmetric generalized diffusion. Simulations are carried out in terms of jump processes X n (⋅). For piece-wise constant functions a ij on ℝ d and piece-wise continuous functions a ij on ℝ 2 the construction and principal algorithm are described enabling an easy implementation into a computer code.

  13. Signature of Fermi surface jumps in positron spectroscopy data

    International Nuclear Information System (INIS)

    Adam, G.; Adam, S.

    1998-12-01

    A subtractionless method for solving Fermi surface sheets (FSS), from measured n-axis-projected momentum distribution histograms by two-dimensional angular correlation of the positron-electron annihilation radiation (2D-ACAR) technique, is discussed. The window least squares statistical noise smoothing filter described in Adam et al., NIM A, 337 (1993) 188, is first refined such that the window free radial parameters (WRP) are optimally adapted to the data. In an ideal single crystal, the specific jumps induced in the WRP distribution by the existing Fermi surface jumps yield straightforward information on the resolved FSS. In a real crystal, the smearing of the derived WRP optimal values, which originates from positron annihilations with electrons at crystal imperfections, is ruled out by median smoothing of the obtained distribution, over symmetry defined stars of bins. The analysis of a gigacount 2D-ACAR spectrum, measured on the archetypal high-T c compound Y Ba 2 Cu 3 O 7-δ at room temperature, illustrates the method. Both electronic FSS, the ridge along Γ Χ direction and the pillbox centered at the S point of the first Brillouin zone, are resolved. (author)

  14. Quantum jumps in a three-level system

    International Nuclear Information System (INIS)

    Javanainen, J.

    1986-01-01

    The authors study fluorescence in a scheme which is easy to treat theoretically: a two-level system driven by a laser and a third metastable state such that slow spontaneous transitions take place both from the excited state of a two-level system to the metastable state and from the metastable state to the ground state of the two-level system. With the aid of the quantum regression theorem the authors calculate the whole photon counting statistics at a detector which records scattering of the laser photons. In the limit of high intensity of the laser, the statistics of photon counts is found to be the same as the statistics of a two-state Markov jumps process. Thus, if the sequence of photon counts can be interpreted as a realization of a stochastic process, in a single experimental run the fluorescence should abruptly turn on and off for random intervals of time. The result is the same as given by the quantum-jump argument

  15. Orthogonal Expansions for VIX Options Under Affine Jump Diffusions

    DEFF Research Database (Denmark)

    Barletta, Andrea; Nicolato, Elisa

    2017-01-01

    In this work we derive new closed–form pricing formulas for VIX options in the jump-diffusion SVJJ model proposed by Duffie et al. (2000). Our approach is based on the classic methodology of approximating a density function with an orthogonal expansion of polynomials weighted by a kernel. Orthogo......In this work we derive new closed–form pricing formulas for VIX options in the jump-diffusion SVJJ model proposed by Duffie et al. (2000). Our approach is based on the classic methodology of approximating a density function with an orthogonal expansion of polynomials weighted by a kernel....... Orthogonal expansions based on the Gaussian distribution, such as Edgeworth or Gram–Charlier expansions, have been successfully employed by a number of authors in the context of equity options. However, these expansions are not quite suitable for volatility or variance densities as they inherently assign...... positive mass to the negative real line. Here we approximate option prices via expansions that instead are based on kernels defined on the positive real line. Specifically, we consider a flexible family of distributions, which generalizes the gamma kernel associated with the classic Laguerre expansions...

  16. Prescription-induced jump distributions in multiplicative Poisson processes

    Science.gov (United States)

    Suweis, Samir; Porporato, Amilcare; Rinaldo, Andrea; Maritan, Amos

    2011-06-01

    Generalized Langevin equations (GLE) with multiplicative white Poisson noise pose the usual prescription dilemma leading to different evolution equations (master equations) for the probability distribution. Contrary to the case of multiplicative Gaussian white noise, the Stratonovich prescription does not correspond to the well-known midpoint (or any other intermediate) prescription. By introducing an inertial term in the GLE, we show that the Itô and Stratonovich prescriptions naturally arise depending on two time scales, one induced by the inertial term and the other determined by the jump event. We also show that, when the multiplicative noise is linear in the random variable, one prescription can be made equivalent to the other by a suitable transformation in the jump probability distribution. We apply these results to a recently proposed stochastic model describing the dynamics of primary soil salinization, in which the salt mass balance within the soil root zone requires the analysis of different prescriptions arising from the resulting stochastic differential equation forced by multiplicative white Poisson noise, the features of which are tailored to the characters of the daily precipitation. A method is finally suggested to infer the most appropriate prescription from the data.

  17. Marcus versus Stratonovich for systems with jump noise

    Science.gov (United States)

    Chechkin, Alexei; Pavlyukevich, Ilya

    2014-08-01

    The famous Itô-Stratonovich dilemma arises when one examines a dynamical system with a multiplicative white noise. In physics literature, this dilemma is often resolved in favour of the Stratonovich prescription because of its two characteristic properties valid for systems driven by Brownian motion: (i) it allows physicists to treat stochastic integrals in the same way as conventional integrals, and (ii) it appears naturally as a result of a small correlation time limit procedure. On the other hand, the Marcus prescription (IEEE Trans. Inform. Theory 24 164 (1978); Stochastics 4 223 (1981)) should be used to retain (i) and (ii) for systems driven by a Poisson process, Lévy flights or more general jump processes. In present communication we present an in-depth comparison of the Itô, Stratonovich and Marcus equations for systems with multiplicative jump noise. By the examples of a real-valued linear system and a complex oscillator with noisy frequency (the Kubo-Anderson oscillator) we compare solutions obtained with the three prescriptions.

  18. Host jumps shaped the diversity of extant rust fungi (Pucciniales).

    Science.gov (United States)

    McTaggart, Alistair R; Shivas, Roger G; van der Nest, Magriet A; Roux, Jolanda; Wingfield, Brenda D; Wingfield, Michael J

    2016-02-01

    The aim of this study was to determine the evolutionary time line for rust fungi and date key speciation events using a molecular clock. Evidence is provided that supports a contemporary view for a recent origin of rust fungi, with a common ancestor on a flowering plant. Divergence times for > 20 genera of rust fungi were studied with Bayesian evolutionary analyses. A relaxed molecular clock was applied to ribosomal and mitochondrial genes, calibrated against estimated divergence times for the hosts of rust fungi, such as Acacia (Fabaceae), angiosperms and the cupressophytes. Results showed that rust fungi shared a most recent common ancestor with a mean age between 113 and 115 million yr. This dates rust fungi to the Cretaceous period, which is much younger than previous estimations. Host jumps, whether taxonomically large or between host genera in the same family, most probably shaped the diversity of rust genera. Likewise, species diversified by host shifts (through coevolution) or via subsequent host jumps. This is in contrast to strict coevolution with their hosts. Puccinia psidii was recovered in Sphaerophragmiaceae, a family distinct from Raveneliaceae, which were regarded as confamilial in previous studies. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  19. Visual Discrimination Learning in the Jumping Spider Phidippus regius

    Directory of Open Access Journals (Sweden)

    Massimo De Agrò

    2017-11-01

    Full Text Available Over the past decade, research in comparative psychology has increasingly focused on non-vertebrate models of cognition. Jumping spiders provide excellent models for the study of visually mediated behaviors, such as associative learning or the navigation of complex environments. Here, we tested visual and memory abilities of Phidippus regius to discriminate between artificial geometrical stimuli and to generalize the learned discrimination to illusory stimuli, using the amodal completion mechanism. Spiders were first trained to associate one shape (‘X’ or ‘O’ with a reward (sugar water, whilst the other shape was associated with an aversive taste (acidic water. Spiders were then asked to choose between the two shapes in the absence of any reward or punishment. They were then presented with an occluded version of the previously rewarded shape to test for the presence of amodal completion. Spiders were able to learn the discrimination task, although the association was not transferred to the illusory stimulus. This study provides the first demonstration of shape discrimination learning in a jumping spider. The results of the test on the illusory shape are discussed considering that either the spiders' visual system may not require amodal completion or they could have the tendency to learn the shape associated with the aversive taste rather than that associated with the reward.

  20. Effect of Reduced Stiffness Dance Flooring on Lower Extremity Joint Angular Trajectories During a Ballet Jump.

    Science.gov (United States)

    Hackney, James; Brummel, Sara; Newman, Mary; Scott, Shannon; Reinagel, Matthew; Smith, Jennifer

    2015-09-01

    We carried out a study to investigate how low stiffness flooring may help prevent overuse injuries of the lower extremity in dancers. It was hypothesized that performing a ballet jump (sauté) on a reduced stiffness dance floor would decrease maximum joint flexion angles and negative angular velocities at the hips, knees, or ankles compared to performing the same jump on a harder floor. The participants were 15 young adult female dancers (age range 18 to 28, mean = 20.89 ± 2.93 years) with at least 5 years of continuous ballet experience and without history of serious lower body injury, surgery, or recent pain. They performed sautés on a (low stiffness) Harlequin ® WoodSpring Floor and on a vinyl-covered hardwood on concrete floor. Maximum joint flexion angles and negative velocities at bilateral hips, knees, and ankles were measured with the "Ariel Performance Analysis System" (APAS). Paired one-tailed t-tests yielded significant decreases in maximum knee angle (average decrease = 3.4° ± 4.2°, p = 0.026) and angular negative velocity of the ankles (average decrease = 18.7°/sec ± 27.9°/sec, p = 0.009) with low stiffness flooring. If the knee angle is less acute, then the length of the external knee flexion moment arm will also be shorter and result in a smaller external knee flexion moment, given an equal landing force. Also, high velocities of eccentric muscle contraction, which are necessary to control negative angular velocity of the ankle joint, are associated with higher risk of musculotendinous injury. Hence, our findings indicate that reduced floor stiffness may indeed help decrease the likelihood of lower extremity injuries.