Golf Ball

Science.gov (United States)

1998-01-01

The Ultra 500 Series golf balls, introduced in 1995 by Wilson Sporting Goods Company, has 500 dimples arranged in a pattern of 60 spherical triangles. The design employs NASA's aerodynamics technology analysis of air loads of the tank and Shuttle orbiter that was performed under the Space Shuttle External Tank program. According to Wilson, this technology provides 'the most symmetrical ball surface available, sustaining initial velocity longer and producing the most stable ball flight for unmatched accuracy and distance.' The dimples are in three sizes, shapes and depths mathematically positioned for the best effect. The selection of dimples and their placement optimizes the interaction of opposing forces of lift and drag. Large dimples reduce air drag, enhance lift, and maintain spin for distance. Small dimples prevent excessive lift that destabilizes the ball flight and the medium size dimples blend the other two.

PROPERTIES OF SWIMMING WATER

Directory of Open Access Journals (Sweden)

Tayfun KIR

2004-10-01

Full Text Available Swimming waters may be hazardous on human health. So, The physicians who work in the facilities, which include swimming areas, are responsible to prevent risks. To ensure hygiene of swimming water, European Swimming Water Directive offers microbiological, physical, and chemical criteria. [TAF Prev Med Bull 2004; 3(5.000: 103-104

Frictional performance of ball screw

International Nuclear Information System (INIS)

Nakashima, Katuhiro; Takafuji, Kazuki

1985-01-01

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

Controlled-frequency breath swimming improves swimming performance and running economy.

Science.gov (United States)

Lavin, K M; Guenette, J A; Smoliga, J M; Zavorsky, G S

2015-02-01

Respiratory muscle fatigue can negatively impact athletic performance, but swimming has beneficial effects on the respiratory system and may reduce susceptibility to fatigue. Limiting breath frequency during swimming further stresses the respiratory system through hypercapnia and mechanical loading and may lead to appreciable improvements in respiratory muscle strength. This study assessed the effects of controlled-frequency breath (CFB) swimming on pulmonary function. Eighteen subjects (10 men), average (standard deviation) age 25 (6) years, body mass index 24.4 (3.7) kg/m(2), underwent baseline testing to assess pulmonary function, running economy, aerobic capacity, and swimming performance. Subjects were then randomized to either CFB or stroke-matched (SM) condition. Subjects completed 12 training sessions, in which CFB subjects took two breaths per length and SM subjects took seven. Post-training, maximum expiratory pressure improved by 11% (15) for all 18 subjects (P swimming may improve muscular oxygen utilization during terrestrial exercise in novice swimmers. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Swimming-pool piles

International Nuclear Information System (INIS)

Trioulaire, M.

1959-01-01

In France two swimming-pool piles, Melusine and Triton, have just been set in operation. The swimming-pool pile is the ideal research tool for neutron fluxes of the order of 10 13 . This type of pile can be of immediate interest to many research centres, but its cost must be reduced and a break with tradition should be observed in its design. It would be an advantage: - to bury the swimming-pool; - to reject the experimental channel; - to concentrate the cooling circuit in the swimming-pool; - to carry out all manipulations in the water; - to double the core. (author) [fr

Individual ball possession in soccer.

Directory of Open Access Journals (Sweden)

Daniel Link

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

Participation in ball sports may represent a prehabilitation strategy to prevent future stress fractures and promote bone health in young athletes.

Science.gov (United States)

Tenforde, Adam Sebastian; Sainani, Kristin Lynn; Carter Sayres, Lauren; Milgrom, Charles; Fredericson, Michael

2015-02-01

Sports participation has many benefits for the young athlete, including improved bone health. However, a subset of athletes may attain suboptimal bone health and be at increased risk for stress fractures. This risk is greater for female than for male athletes. In healthy children, high-impact physical activity has been shown to improve bone health during growth and development. We offer our perspective on the importance of promoting high-impact, multidirectional loading activities, including ball sports, as a method of enhancing bone quality and fracture prevention based on collective research. Ball sports have been associated with greater bone mineral density and enhanced bone geometric properties compared with participation in repetitive, low-impact sports such as distance running or nonimpact sports such as swimming. Runners and infantry who participated in ball sports during childhood were at decreased risk of future stress fractures. Gender-specific differences, including the coexistence of female athlete triad, may negate the benefits of previous ball sports on fracture prevention. Ball sports involve multidirectional loading with high ground reaction forces that may result in stiffer and more fracture-resistant bones. Encouraging young athletes to participate in ball sports may optimize bone health in the setting of adequate nutrition and in female athletes, eumenorrhea. Future research to determine timing, frequency, and type of loading activity could result in a primary prevention program for stress fracture injuries and improved life-long bone health. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Swimming Performance of Adult Asian Carp: Field Assessment Using a Mobile Swim Tunnel

Science.gov (United States)

2016-08-01

ERDC/TN ANSRP-16-1 August 2016 Approved for public release; distribution is unlimited. Swimming Performance of Adult Asian Carp: Field...Assessment Using a Mobile Swim Tunnel by Jan Jeffrey Hoover, Jay A. Collins, Alan W. Katzenmeyer, and K. Jack Killgore PURPOSE: Empirical swim speed...test in traditional laboratory swim tunnels. Biologists from the Engineer Research and Development Center (ERDC) Environmental Laboratory (EL), with

The influence of elements of synchronized swimming on technique of the selected swimming strokes

OpenAIRE

Široký, Michal

2015-01-01

Title: The influence of elements of synchronized swimming on technique of the selected swimming strokes Objectives: The objective of the thesis is to assess the effect of the elements of synchronized swimming at improving the techniques of swimming. Methods: The results were detected by overt observation with active participation and subsequent scaling on the ordinal scale 1 to 5. Results: The results show that the influence of the elements of synchronized swimming on improving the technique ...

Street children

Directory of Open Access Journals (Sweden)

Rončević Nevenka

2013-01-01

Full Text Available According to UNICEF, street child is any child under the age of 18 for whom the street has become home and/or source of income and which is not adequately protected or supervised by adult, responsible person. It has been estimated that there are between 100 and 150 million street children worldwide. Life and work on the street have long term and far-reaching consequences for development and health of these children. By living and working in the street, these children face the highest level of risk. Street children more often suffer from the acute illness, injuries, infection, especially gastrointestinal, acute respiratory infections and sexually transmitted diseases, inadequate nutrition, mental disorders, and drug abuse. They are more often victims of abuse, sexual exploitation, trafficking; they have higher rate of adolescent pregnancy than their peers from poor families. Street children and youth have higher rates of hospitalization and longer hospital stay due to seriousness of illness and delayed health care. Street children/youth are reluctant to seek health care, and when they try, they face many barriers. Street children are invisible to the state and their number in Serbia is unknown. Recently, some non­governmental organizations from Belgrade, Novi Sad and Nis have recognized this problem and tried to offer some help to street children, by opening drop­in centers, but this is not enough. To solve this problem, an engagement of the state and the whole community is necessary, and primary responsibility lies in health, social and educational sector. The best interests of the child must serve as a basic guideline in all activities aimed at improving health, quality of life and rights of children involved in the life and work in the street.

Ceramic Rail-Race Ball Bearings

Science.gov (United States)

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

2010-01-01

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

Analysis of swimming performance: perceptions and practices of US-based swimming coaches.

Science.gov (United States)

Mooney, Robert; Corley, Gavin; Godfrey, Alan; Osborough, Conor; Newell, John; Quinlan, Leo Richard; ÓLaighin, Gearóid

2016-01-01

In elite swimming, a broad range of methods are used to assess performance, inform coaching practices and monitor athletic progression. The aim of this paper was to examine the performance analysis practices of swimming coaches and to explore the reasons behind the decisions that coaches take when analysing performance. Survey data were analysed from 298 Level 3 competitive swimming coaches (245 male, 53 female) based in the United States. Results were compiled to provide a generalised picture of practices and perceptions and to examine key emerging themes. It was found that a disparity exists between the importance swim coaches place on biomechanical analysis of swimming performance and the types of analyses that are actually conducted. Video-based methods are most frequently employed, with over 70% of coaches using these methods at least monthly, with analyses being mainly qualitative in nature rather than quantitative. Barriers to the more widespread use of quantitative biomechanical analysis in elite swimming environments were explored. Constraints include time, cost and availability of resources, but other factors such as sources of information on swimming performance and analysis and control over service provision are also discussed, with particular emphasis on video-based methods and emerging sensor-based technologies.

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

Science.gov (United States)

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

2014-02-01

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

The Effect of Swimming Experience on Acquisition and Retention of Swimming-Based Taste Aversion Learning in Rats

Science.gov (United States)

Masaki, Takahisa; Nakajima, Sadahiko

2010-01-01

Swimming endows rats with an aversion to a taste solution consumed before swimming. The present study explored whether the experience of swimming before or after the taste-swimming trials interferes with swimming-based taste aversion learning. Experiment 1 demonstrated that a single preexposure to 20 min of swimming was as effective as four or…

Urban streets

NARCIS (Netherlands)

Schönfeld, von Kim Carlotta; Bertolini, Luca

2017-01-01

Today's urban streets are usually planned for purposes of mobility: pedestrians, as well as a variety of vehicles such as cars, trucks, and sometimes bicycles, are usually factored into an urban street plan. However, urban streets are also increasingly recognized as public spaces, accommodating

Swimming pool granuloma

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/001357.htm Swimming pool granuloma To use the sharing features on this page, please enable JavaScript. A swimming pool granuloma is a long-term (chronic) skin ...

Optical and Acoustic Sensor-Based 3D Ball Motion Estimation for Ball Sport Simulators †

Directory of Open Access Journals (Sweden)

Sang-Woo Seo

2018-04-01

Full Text Available Estimation of the motion of ball-shaped objects is essential for the operation of ball sport simulators. In this paper, we propose an estimation system for 3D ball motion, including speed and angle of projection, by using acoustic vector and infrared (IR scanning sensors. Our system is comprised of three steps to estimate a ball motion: sound-based ball firing detection, sound source localization, and IR scanning for motion analysis. First, an impulsive sound classification based on the mel-frequency cepstrum and feed-forward neural network is introduced to detect the ball launch sound. An impulsive sound source localization using a 2D microelectromechanical system (MEMS microphones and delay-and-sum beamforming is presented to estimate the firing position. The time and position of a ball in 3D space is determined from a high-speed infrared scanning method. Our experimental results demonstrate that the estimation of ball motion based on sound allows a wider activity area than similar camera-based methods. Thus, it can be practically applied to various simulations in sports such as soccer and baseball.

The bowling balls

CERN Multimedia

CERN Bulletin

2010-01-01

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

Diarrhea and Swimming

Science.gov (United States)

... 888) 232-6348 Contact CDC–INFO Healthy Swimming Health Benefits of Water-based Exercise Swimmer Protection Steps of ... Disinfection Microbial Testing & Disinfection Swimming Pool Chemicals Injuries & Outdoor Health International Recreational Water RWIs, Swimmer Hygiene, & Behavioral ...

46th Street pilot street lighting project.

Science.gov (United States)

2013-01-01

Street lighting improvements provide an opportunity for governments to save money and to reduce their : environmental footprint. New energy-efficient technologies are being perfected that are more efficient than : standard high-pressure sodium street...

The spinning ball spiral

International Nuclear Information System (INIS)

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

2010-01-01

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

Compact Q-balls

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-10

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

Swimming level classification of young school age children and their success in a long distance swimming test

OpenAIRE

Nováková, Martina

2010-01-01

Title: Swimming level classification of young school age children and their success in a long distance swimming test Work objectives: The outcome of our work is comparison and evaluation of the initial and final swimming lenght in a test of long distance swimming. This test is taken during one swimming course. Methodology: Data which were obtained by testing a certain group of people and were statistically processed, showed the swimming level and performance of the young school age children. ...

Swimming ability and physiological response to swimming fatigue in ...

African Journals Online (AJOL)

The swimming endurance of kuruma shrimp, Marsupenaeus japonicus (11.04 ± 2.43 g) at five swimming speeds (23.0, 26.7, 31.0, 34.6 and 38.6 cm s-1) was determined in a circulating flume at 25.7 ± 0.7°C. The plasma glucose and total protein, hepatopancreas and pleopods muscle glycogen concentrations were ...

Laryngoscopy during swimming

DEFF Research Database (Denmark)

Walsted, Emil S; Swanton, Laura L; van van Someren, Ken

2017-01-01

that precipitates their symptoms. This report provides the first description of the feasibility of performing continuous laryngoscopy during exercise in a swimming environment. The report describes the methodology and safety of the use of continuous laryngoscopy while swimming. Laryngoscope, 2017....

[Sharing and distrusting: street merchants' view of children in street situations].

Science.gov (United States)

Sánchez-Suárez, Diana M; Giraldo-Puerta, Alexandra; Giraldo-Pineda, Álvaro; Forero-Pulido, Constanza

2016-06-01

Objective To understand the meanings, through the description of experiences that street merchants have of their interactions with children in a street situation in downtown of Medellin in 2013. Methodology Qualitative investigation with ethnographic approach. Observations were made in the zone at different times of the day. Twelve interviews with street merchants were held in their work places. Records were kept in a field journal. Results The street merchants and children in street situations share the same space. Both groups try to survive and their relationship is mediated by the trust-distrust that is established between them. The coexistence generates ambivalent feelings. For the street merchants, children in street situations are the result of abandonment by the family, the state and society. They live in a hard world in which they are exposed to a series of risks that they must face. Conclusion The interaction between street merchants and children in street situations is good to the extent that conflicts are avoided, establishing norms of coexistence. The element that determines this relationship is trust-distrust. In trust, strong affective ties are generated, considering each other family. Distrust generates a preventative attitude.

Factors influencing termination of swimming career of children at sport swimming classes

OpenAIRE

Pištěková, Petra

2007-01-01

Title: The Cause ofan Early End ofPupils' Swimming Career The aim of the thesis: Determination ofthe most frequent reasons for an early end ofpupils' swimming career. Method: The reasons for an early end ofpupils' swimming career were discovered by using questionnaires. Forty-five former pupils from special sports elementary schools were questioned and then the data were compared with available literature. Results: Research investigated changes in the most frequent reasons for an early end of...

Paramecia swimming in viscous flow

Science.gov (United States)

Zhang, P.; Jana, S.; Giarra, M.; Vlachos, P. P.; Jung, S.

2015-12-01

Ciliates like Paramecia exhibit fore-aft asymmetry in their body shapes, and preferentially swim in the direction of the slender anterior rather than the wider posterior. However, the physical reasons for this preference are not well understood. In this work, we propose that specific features of the fluid flow around swimming Paramecia confer some energetic advantage to the preferred swimming direction. Therefore, we seek to understand the effects of body asymmetry and swimming direction on the efficiency of swimming and the flux of fluid into the cilia layer (and thus of food into the oral groove), which we assumed to be primary factors in the energy budgets of these organisms. To this end, we combined numerical techniques (the boundary element method) and laboratory experiments (micro particle image velocimetry) to develop a quantitative model of the flow around a Paramecium and investigate the effect of the body shape on the velocity fields, as well as on the swimming and feeding behaviors. Both simulation and experimental results show that velocity fields exhibit fore-aft asymmetry. Moreover, the shape asymmetry revealed an increase of the fluid flux into the cilia layer compared to symmetric body shapes. Under the assumption that cilia fluid intake and feeding efficiency are primary factors in the energy budgets of Paramecia, our model predicts that the anterior swimming direction is energetically favorable to the posterior swimming direction.

Swimming activity in marine fish.

Science.gov (United States)

Wardle, C S

1985-01-01

Marine fish are capable of swimming long distances in annual migrations; they are also capable of high-speed dashes of short duration, and they can occupy small home territories for long periods with little activity. There is a large effect of fish size on the distance fish migrate at slow swimming speeds. When chased by a fishing trawl the effect of fish size on swimming performance can decide their fate. The identity and thickness of muscle used at each speed and evidence for the timing of myotomes used during the body movement cycle can be detected using electromyogram (EMG) electrodes. The cross-sectional area of muscle needed to maintain different swimming speeds can be predicted by relating the swimming drag force to the muscle force. At maximum swimming speed one completed cycle of swimming force is derived in sequence from the whole cross-sectional area of the muscles along the two sides of the fish. This and other aspects of the swimming cycle suggest that each myotome might be responsible for generating forces involved in particular stages of the tail sweep. The thick myotomes at the head end shorten during the peak thrust of the tail blade whereas the thinner myotomes nearer the tail generate stiffness appropriate for transmission of these forces and reposition the tail for the next cycle.

LHC gets the ball rolling

CERN Multimedia

2007-01-01

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

Street as Public Space - Measuring Street Life of Kuala Lumpur

Science.gov (United States)

Sulaiman, Normah; Ayu Abdullah, Yusfida; Hamdan, Hazlina

2017-10-01

Kuala Lumpur has envisioning in becoming World Class City by the year 2020. Essential elements of form and function of the urban environment are streets. Streets showcase the community and connect people. It’s one of the most comfortable social environment that provides aesthetical and interaction pleasure for everyone. Classified as main shopping streets in the local Kuala Lumpur urban design guidelines, Jalan Masjid India (JMI) has its uniqueness of shopping experience and social interaction. This conceptual paper will study the physical and cultural characteristics of the street that will generate the street character by mapping its original characters. The findings will focus on strengthening the methodology applied to promote improvements in evaluating it as a great public space. Results will also contribute to understanding the overall site context, the street connectivity, and urban dynamics. This paper is part of a larger study that addresses on transforming the sociability of public space.

Simple street tree sampling

Science.gov (United States)

David J. Nowak; Jeffrey T. Walton; James Baldwin; Jerry. Bond

2015-01-01

Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of...

Pre-task music improves swimming performance.

Science.gov (United States)

Smirmaul, B P; Dos Santos, R V; Da Silva Neto, L V

2015-12-01

The purpose of this study was to investigate the effects of pre-task music on swimming performance and other psychological variables. A randomized counterbalanced within-subjects (experimental and control condition) design was employed. Eighteen regional level male swimmers performed two 200-m freestyle swimming time trials. Participants were exposed to either 5 minutes of self-selected music (pre-task music condition) or 5 minutes of silence (control condition) and, after 1 minute, performed the swimming task. Swimming time was significantly shorter (-1.44%) in the pre-task music condition. Listening to pre-task music increased motivation to perform the swimming task, while arousal remained unchanged. While fatigue increased after the swimming task in both conditions, vigor, ratings of perceived exertion and affective valence were unaltered. It is concluded, for the first time, that pre-task music improves swimming performance.

21 CFR 1250.89 - Swimming pools.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Swimming pools. 1250.89 Section 1250.89 Food and... SANITATION Sanitation Facilities and Conditions on Vessels § 1250.89 Swimming pools. (a) Fill and draw swimming pools shall not be installed or used. (b) Swimming pools of the recirculation type shall be...

36 CFR 331.10 - Swimming.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Swimming. 331.10 Section 331.10 Parks, Forests, and Public Property CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY REGULATIONS..., KENTUCKY AND INDIANA § 331.10 Swimming. Swimming is prohibited unless authorized in writing by the District...

36 CFR 327.5 - Swimming.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Swimming. 327.5 Section 327.5 Parks, Forests, and Public Property CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY RULES AND REGULATIONS... Swimming. (a) Swimming, wading, snorkeling or scuba diving at one's own risk is permitted, except at...

Violence in the Street, Violence of the Street

DEFF Research Database (Denmark)

Heinskou, Marie Bruvik; Liebst, Lasse Suonperä

While in his early and general theory of interaction rituals Randall Collins emphasised that social situations are both ’symbolic’ and ’material’, the latter dimension is largely absent from Collins’ theory of violence(Collins 2004; 1993: 214). Compared with criminology’s more recent situational...... studies of violence, it is noticeable that the analytical success of these studies is closely linked with understanding street violence as a spatial-situational phenomenon (Clarke 1997; Eck & Weisburd 1995; Bragand & Weisburd; 2010; Wikström et al. 2012; Sampson et al. 1997). In light of evidence...... for the spatial concentration of street violence, this paper takes its point of departure in a large study of Street Violence among youth in Copenhagen, Denmark (combining quantitative data from filed police reports (N = 501), data from CCTV (N=100) and qualitative analysis of selected cases of street violence...

43 CFR 423.36 - Swimming.

Science.gov (United States)

2010-10-01

... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Swimming. 423.36 Section 423.36 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF RECLAMATION, DEPARTMENT OF THE INTERIOR... Swimming. (a) You may swim, wade, snorkel, scuba dive, raft, or tube at your own risk in Reclamation waters...

Locomotor activity during the frenzy swim: analysing early swimming behaviour in hatchling sea turtles.

Science.gov (United States)

Pereira, Carla M; Booth, David T; Limpus, Colin J

2011-12-01

Swimming effort of hatchling sea turtles varies across species. In this study we analysed how swim thrust is produced in terms of power stroke rate, mean maximum thrust per power stroke and percentage of time spent power stroking throughout the first 18 h of swimming after entering the water, in both loggerhead and flatback turtle hatchlings and compared this with previous data from green turtle hatchlings. Loggerhead and green turtle hatchlings had similar power stroke rates and percentage of time spent power stroking throughout the trial, although mean maximum thrust was always significantly higher in green hatchlings, making them the most vigorous swimmers in our three-species comparison. Flatback hatchlings, however, were different from the other two species, with overall lower values in all three swimming variables. Their swimming effort dropped significantly during the first 2 h and kept decreasing significantly until the end of the trial at 18 h. These results support the hypothesis that ecological factors mould the swimming behaviour of hatchling sea turtles, with predator pressure being important in determining the strategy used to swim offshore. Loggerhead and green turtle hatchlings seem to adopt an intensely vigorous and energetically costly frenzy swim that would quickly take them offshore into the open ocean in order to reduce their exposure to near-shore aquatic predators. Flatback hatchlings, however, are restricted in geographic distribution and remain within the continental shelf region where predator pressure is probably relatively constant. For this reason, flatback hatchlings might use only part of their energy reserves during a less vigorous frenzy phase, with lower overall energy expenditure during the first day compared with loggerhead and green turtle hatchlings.

The Goldenrod Ball Gall

Science.gov (United States)

Fischer, Richard B.

1974-01-01

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

Hydrodynamic advantages of swimming by salp chains.

Science.gov (United States)

Sutherland, Kelly R; Weihs, Daniel

2017-08-01

Salps are marine invertebrates comprising multiple jet-propelled swimming units during a colonial life-cycle stage. Using theory, we show that asynchronous swimming with multiple pulsed jets yields substantial hydrodynamic benefit due to the production of steady swimming velocities, which limit drag. Laboratory comparisons of swimming kinematics of aggregate salps ( Salpa fusiformis and Weelia cylindrica ) using high-speed video supported that asynchronous swimming by aggregates results in a smoother velocity profile and showed that this smoother velocity profile is the result of uncoordinated, asynchronous swimming by individual zooids. In situ flow visualizations of W. cylindrica swimming wakes revealed that another consequence of asynchronous swimming is that fluid interactions between jet wakes are minimized. Although the advantages of multi-jet propulsion have been mentioned elsewhere, this is the first time that the theory has been quantified and the role of asynchronous swimming verified using experimental data from the laboratory and the field. © 2017 The Author(s).

Dynamics of a Bouncing Ball

Science.gov (United States)

Liang, Shiuan-Ni; Lan, Boon Leong

The dynamics of a bouncing ball undergoing repeated inelastic impacts with a table oscillating vertically in a sinusoidal fashion is studied using Newtonian mechanics and general relativistic mechanics. An exact mapping describes the bouncing ball dynamics in each theory. We show, contrary to expectation, that the trajectories predicted by Newtonian mechanics and general relativistic mechanics from the same parameters and initial conditions for the ball bouncing at low speed in a weak gravitational field can rapidly disagree completely. The bouncing ball system could be realized experimentally to test which of the two different predicted trajectories is correct.

Swimming pool cleaner poisoning

Science.gov (United States)

Swimming pool cleaner poisoning occurs when someone swallows this type of cleaner, touches it, or breathes in ... The harmful substances in swimming pool cleaner are: Bromine ... copper Chlorine Soda ash Sodium bicarbonate Various mild acids

A Correlational Analysis of Tethered Swimming, Swim Sprint Performance and Dry-land Power Assessments.

Science.gov (United States)

Loturco, I; Barbosa, A C; Nocentini, R K; Pereira, L A; Kobal, R; Kitamura, K; Abad, C C C; Figueiredo, P; Nakamura, F Y

2016-03-01

Swimmers are often tested on both dry-land and in swimming exercises. The aim of this study was to test the relationships between dry-land, tethered force-time curve parameters and swimming performances in distances up to 200 m. 10 young male high-level swimmers were assessed using the maximal isometric bench-press and quarter-squat, mean propulsive power in jump-squat, squat and countermovement jumps (dry-land assessments), peak force, average force, rate of force development (RFD) and impulse (tethered swimming) and swimming times. Pearson product-moment correlations were calculated among the variables. Peak force and average force were very largely correlated with the 50- and 100-m swimming performances (r=- 0.82 and -0.74, respectively). Average force was very-largely/largely correlated with the 50- and 100-m performances (r=- 0.85 and -0.67, respectively). RFD and impulse were very-largely correlated with the 50-m time (r=- 0.72 and -0.76, respectively). Tethered swimming parameters were largely correlated (r=0.65 to 0.72) with mean propulsive power in jump-squat, squat-jump and countermovement jumps. Finally, mean propulsive power in jump-squat was largely correlated (r=- 0.70) with 50-m performance. Due to the significant correlations between dry-land assessments and tethered/actual swimming, coaches are encouraged to implement strategies able to increase leg power in sprint swimmers. © Georg Thieme Verlag KG Stuttgart · New York.

Simulation of ball motion and energy transfer in a planetary ball mill

International Nuclear Information System (INIS)

Lu Sheng-Yong; Mao Qiong-Jing; Li Xiao-Dong; Yan Jian-Hua; Peng Zheng

2012-01-01

A kinetic model is proposed for simulating the trajectory of a single milling ball in a planetary ball mill, and a model is also proposed for simulating the local energy transfer during the ball milling process under no-slip conditions. Based on the kinematics of ball motion, the collision frequency and power are described, and the normal impact forces and effective power are derived from analyses of collision geometry. The Hertzian impact theory is applied to formulate these models after having established some relationships among the geometric, dynamic, and thermophysical parameters. Simulation is carried out based on two models, and the effects of the rotation velocity of the planetary disk Ω and the vial-to-disk speed ratio ω/Ω on other kinetic parameters is investigated. As a result, the optimal ratio ω/Ω to obtain high impact energy in the standard operating condition at Ω = 800 rpm is estimated, and is equal to 1.15. (interdisciplinary physics and related areas of science and technology)

Ceramic ball grid array package stress analysis

Science.gov (United States)

Badri, S. H. B. S.; Aziz, M. H. A.; Ong, N. R.; Sauli, Z.; Alcain, J. B.; Retnasamy, V.

2017-09-01

The ball grid array (BGA), a form of chip scale package (CSP), was developed as one of the most advanced surface mount devices, which may be assembled by an ordinary surface ball bumps are used instead of plated nickel and gold (Ni/Au) bumps. Assembly and reliability of the BGA's printed circuit board (PCB), which is soldered by conventional surface mount technology is considered in this study. The Ceramic Ball Grid Array (CBGA) is a rectangular ceramic package or square-shaped that will use the solder ball for external electrical connections instead of leads or wire for connections. The solder balls will be arranged in an array or grid at the bottom of the ceramic package body. In this study, ANSYS software is used to investigate the stress on the package for 2 balls and 4 balls of the CBGA package with the various force range of 1-3 Newton applied to the top of the die, top of the substrate and side of the substrate. The highest maximum stress was analyzed and the maximum equivalent stress was observed on the solder ball and the die. From the simulation result, the CBGA package with less solder balls experience higher stress compared to the package with many solder balls. Therefore, less number of solder ball on the CBGA package results higher stress and critically affect the reliability of the solder balls itself, substrate and die which can lead to the solder crack and also die crack.

Healthy Swimming/Recreational Water

Science.gov (United States)

... Medical Professionals En Español Publications, Data, & Statistics Healthy Swimming Resources Health Promotion Materials Find Your State Training & ... Announcements Outbreak Response Toolkits CDC at Work: Healthy Swimming Fast Facts Index of Water-Related Topics Model ...

Swimming Performance and Metabolism of Golden Shiners

Science.gov (United States)

The swimming ability and metabolism of golden shiners, Notemigonus crysoleucas, was examined using swim tunnel respirometery. The oxygen consumption and tail beat frequencies at various swimming speeds, an estimation of the standard metabolic rate, and the critical swimming speed (Ucrit) was determ...

Safety of street: The role of street design

Science.gov (United States)

Rashid, Suhaila Abdul; Wahab, Mohammad Hussaini; Rani, Wan Nurul Mardiah Wan Mohd.; Ismail, Syuhaida

2017-10-01

Living in the cities poses many challenges for the vulnerable group of user especially women where they are exposed to many issues related to safety. With the changing of lifestyle and demands, women are expected to play multiple roles in the society and working is one of the tasks. When women are expected to be working as men do, they are no longer occupied at one place. Women nowadays travel on a daily basis and being in the streets is one of the important activities. With the influx of diverse group of people into the country, our streets are dominated by different types of people from different background. Due to these factors, there are possibilities of challenges and threats for users especially women. Therefore, city spaces especially the street become an important public realm for women. The design of the street should be able to make women feel safe as these are the public space where they spend time getting to and from work. The way women perceived their environment might be different from men especially when they fear of crime. Perception of safety will affect the quality of life where fear is an important psychological factor in human life. Living in fear will restrict human's freedom. Therefore, this study aimed to explore women's perception of safety in the streets of Kuala Lumpur. The study adopted a mixed-method approach of qualitative and quantitative in order to understand the safety perception among women that will later establish the relationship between built environment and human psychology. 120 respondents were selected randomly around Jalan Benteng, Jalan Tun Perak, Jalan Melaka and Jalan Melayu. Questionnaire survey forms were distributed and structured observation was conducted at interval period at these streets to examined and assess women's behavior. Finding shows that fear does affect women's perception and physical design of the streets are important in affecting their behavior.

2012 Problem 15: Frustrating Golf Ball

Science.gov (United States)

Huang, Shan; Zhu, Zheyuan; Gao, Wenli; Wang, Sihui

2015-10-01

This paper studies the condition for a golf ball to escape from a hole. The two determining factors are the ball's initial velocity v0 and its deviation from the center of the hole d. There is a critical escaping velocity vc for every deviation d. The ball's motion is analyzed by calculating the change of velocity whenever the ball collides with the hole. The critical conditions predicted by our theory are verified through experiment.

Swimming literacy field hockey woman player ground.

OpenAIRE

Baštová, Miroslava

2012-01-01

Title: Swimming literacy field hockey woman player ground. Objectives: To obtain and analyze data on the level ground swimming literacy field hockey woman player. Their perception swimming literacy for life, the use of non-specific regeneration and as a training resource. Methods: Analysis of scientific literature, survey, case study, data analysis and graphical presentation of results. Results of the work: field hockey player as swimming literate, benefits swimming but not used as a means of...

Model-based observer and feedback control design for a rigid Joukowski foil in a Kármán vortex street.

Science.gov (United States)

Free, Brian A; Paley, Derek A

2018-03-14

Obstacles and swimming fish in flow create a wake with an alternating left/right vortex pattern known as a Kármán vortex street and reverse Kármán vortex street, respectively. An energy-efficient fish behavior resembling slaloming through the vortex street is called Kármán gaiting. This paper describes the use of a bioinspired array of pressure sensors on a Joukowski foil to estimate and control flow-relative position in a Kármán vortex street using potential flow theory, recursive Bayesian filtering, and trajectory-tracking feedback control. The Joukowski foil is fixed in downstream position in a flowing water channel and free to move on air bearings in the cross-stream direction by controlling its angle of attack to generate lift. Inspired by the lateral-line neuromasts found in fish, the sensing and control scheme is validated using off-the-shelf pressure sensors in an experimental testbed that includes a flapping device to create vortices. We derive a potential flow model that describes the flow over a Joukowski foil in a Kármán vortex street and identify an optimal path through a Kármán vortex street using empirical observability. The optimally observable trajectory is one that passes through each vortex in the street. The estimated vorticity and location of the Kármán vortex street are used in a closed-loop control to track either the optimally observable path or the energetically efficient gait exhibited by fish. Results from the closed-loop control experiments in the flow tank show that the artificial lateral line in conjunction with a potential flow model and Bayesian estimator allow the robot to perform fish-like slaloming behavior in a Kármán vortex street. This work is a precursor to an autonomous robotic fish sensing the wake of another fish and/or performing pursuit and schooling behavior.

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

NARCIS (Netherlands)

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

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

Swimming education in Australian society.

OpenAIRE

Lynch, TJ

2014-01-01

Abstract: The purpose of this paper is to explore a community swimming program using autoethnography qualitative research. Autoethnography is an approach to research and writing that seeks to describe and systematically analyze (graphy) personal experience (auto) in order to understand cultural experience (ethno) (Ellis 2004; Holman Jones 2005). Through childhood reflection of lived swimming experiences, and adult life reflection of lived swimming teaching experiences as a primary school teac...

Ball mounting fixture for a roundness gage

Science.gov (United States)

Gauler, Allen L.; Pasieka, Donald F.

1983-01-01

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

POLICY EVALUATION OF RESTRUCTURING STREET VENDORS IN SURAKARTA CITY (Study of Street Vendors in Monument Park Banjarsari and Street Vendors in Manahan Stadium

Directory of Open Access Journals (Sweden)

Frahlevi Prajasari

2015-08-01

Full Text Available This study examined the policy evaluation of restructuring street vendors in Surakarta city. Street vendors represent the economic actors in the informal sector of urban economic activity. The government of City/District usually removes these street vendors by disguising this activity behind the reason of structuring, . The study used descriptive research with a qualitative approach. The relocation of street vendors in Surakarta City is orderly and smooth without violence which may impact badly on physic and material because the government of Surakarta City, especially Surakarta Mayor, uses persuasive approach. Notoharjo Market is a relocation place for street vendors at Banjarsari Monument Park. In the beginning, Notoharjo Market is crowded with buyers but current days, street vendors who occupy Notoharjo Market complain about lack of buyers. The lack of buyers at Notoharjo Market is because the facilities previously provided by the government of Surakarta City are not well maintained. The government of Surakarta City must listening all complains of street vendors for the smoothness and orderliness of trading activity of street vendors. Not only listening, but the government of Surakarta City also gives appropriate and best solution to street vendors such that street vendors feel comfort in selling and their income is better than before.

The evolution of phenotypic plasticity in fish swimming

Science.gov (United States)

Oufiero, Christopher E.; Whitlow, Katrina R.

2016-01-01

Abstract Fish have a remarkable amount of variation in their swimming performance, from within species differences to diversity among major taxonomic groups. Fish swimming is a complex, integrative phenotype and has the ability to plastically respond to a myriad of environmental changes. The plasticity of fish swimming has been observed on whole-organismal traits such as burst speed or critical swimming speed, as well as underlying phenotypes such as muscle fiber types, kinematics, cardiovascular system, and neuronal processes. Whether the plastic responses of fish swimming are beneficial seems to depend on the environmental variable that is changing. For example, because of the effects of temperature on biochemical processes, alterations of fish swimming in response to temperature do not seem to be beneficial. In contrast, changes in fish swimming in response to variation in flow may benefit the fish to maintain position in the water column. In this paper, we examine how this plasticity in fish swimming might evolve, focusing on environmental variables that have received the most attention: temperature, habitat, dissolved oxygen, and carbon dioxide variation. Using examples from previous research, we highlight many of the ways fish swimming can plastically respond to environmental variation and discuss potential avenues of future research aimed at understanding how plasticity of fish swimming might evolve. We consider the direct and indirect effects of environmental variation on swimming performance, including changes in swimming kinematics and suborganismal traits thought to predict swimming performance. We also discuss the role of the evolution of plasticity in shaping macroevolutionary patterns of diversity in fish swimming. PMID:29491937

Structure and magnetism of SmCo5 nanoflakes prepared by surfactant-assisted ball milling with different ball sizes

International Nuclear Information System (INIS)

Nie, Junwu; Han, Xianghua; Du, Juan; Xia, Weixing; Zhang, Jian; Guo, Zhaohui; Yan, Aru; Li, Wei; Ping Liu, J.

2013-01-01

Anisotropic magnetic SmCo 5 nanoflakes have been fabricated by surfactant-assisted ball milling (SABM) using hardened steel balls of one of the following sizes: 4, 6.5, 9.5 and 12.7 mm in diameters. The magnetic properties of SmCo 5 particles prepared by SABM with different milling ball sizes in diameters were investigated systematically. It was showed that the nanoflakes milled by amount of small size balls had a higher coercivity and lower anisotropy, i.e., worse grain orientation although in a short milling time while the nanoflakes prepared with same weight of big balls tend to have a lower coercivity, better grain orientation. The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning. The SEM analysis shows that the morphology of nanoflakes prepared with different ball sizes are almost the same when the balls to powder weight ratio is fixed. The different magnetic properties caused by different ball sizes are mainly due to the different microstructure changes, i.e, grain refinement and c-axis orientation, which are demonstrated by X-ray diffraction (XRD) analysis and transmission electron microscope (TEM). Based on the experiments above, a combined milling process was suggested and done to improve magnetic properties as your need. - Highlights: • We fabricated anisotropic magnetic SmCo 5 nanoflakes by surfactant-assisted ball milling (SABM). • We investigated the magnetic properties of SmCo 5 particles systematically. It was showed that the coercivity, high or low, and grain orientation, good or bad, were influenced strongly by balls size. The different magnetisms caused by different ball sizes is mainly due to the different microstructure changes. • The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning

Street Children and Employment Opportunities

International Nuclear Information System (INIS)

Enos, H.N.; Njoka, M.

1999-01-01

Although there is a general realization that there are 'people' in the streets, we often take the phenomenon for granted probably because we wake up and go home only to come to the streets the following morning and still find the people. This situation is however changing with the emergence of 'birth' and increase of street children as we begin to take into consideration the category of people to be routinely found on the streets. The phrase 'street children' refer to the children below the statutory adult age living on or found on the streets. These children derive their livelihood from the streets. While the children on the streets may have a 'home' to go to, the latter are an integral part of the street having nowhere to retire to at the end of the day. The street children live in abject poverty and are exposed to many risks. They suffer from malnutrition and deficiency diseases due to low and poor nutrition intake. The street girls get trapped in teenage prostitution quite early in life. Of concern are the issues related to the working street children. Many street children engage in collecting and selling waste paper, bottles and plastics. They are referred to as 'chokora' because of their work of turning garbage upside down as they look for something useful. Unfortunately they have to sell these wastes to powerful forces including people who underpay and harrass them

Study of soccer ball flight trajectory

Directory of Open Access Journals (Sweden)

Javorova Juliana

2018-01-01

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

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

Science.gov (United States)

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

2018-04-01

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

SWIM EVERYDAY TO KEEP DEMENTIA AWAY

Directory of Open Access Journals (Sweden)

Nirmal Singh

2005-03-01

Full Text Available A sound mind resides in a sound body. Many individuals with an active lifestyle show sharp mental skills at an advanced age. Regular exercise has been shown to exert numerous beneficial effects on brawn as well as brain. The present study was undertaken to evaluate the influence of swimming on memory of rodents. A specially designed hexagonal water maze was used for the swimming exposures of animals. The learning and memory parameters were measured using exteroceptive behavioral models such as Elevated plus-maze, Hebb-Williams maze and Passive avoidance apparatus. The rodents (rats and mice were divided into twelve groups. The swimming exposure to the rodents was for 10- minute period during each session and there were two swimming exposures on each day. Rats and mice were subjected to swimming for -15 and -30 consecutive days. Control group animals were not subjected to swimming during above period. The learning index and memory score of all the animals was recorded on 1st, 2nd, 15th, 16th, 30th and 31st day employing above exteroceptive models. It was observed that rodents that underwent swimming regularly for 30- days showed sharp memories, when tested on above behavioral models whereas, control group animals showed decline in memory scores. Those animals, which underwent swimming for 15- days only showed good memory on 16th day, which however, declined after 30-days. These results emphasize the role of regular physical exercise particularly swimming in the maintenance and promotion of brain functions. The underlying physiological mechanism for improvement of memory appears to be the result of enhanced neurogenesis.

Biomechanical Analysis of the Swim-Start: A Review

Directory of Open Access Journals (Sweden)

Julien Vantorre, Didier Chollet, Ludovic Seifert

2014-06-01

Full Text Available This review updates the swim-start state of the art from a biomechanical standpoint. We review the contribution of the swim-start to overall swimming performance, the effects of various swim-start strategies, and skill effects across the range of swim-start strategies identified in the literature. The main objective is to determine the techniques to focus on in swimming training in the contemporary context of the sport. The phases leading to key temporal events of the swim-start, like water entry, require adaptations to the swimmer’s chosen technique over the course of a performance; we thus define the swim-start as the moment when preparation for take-off begins to the moment when the swimming pattern begins. A secondary objective is to determine the role of adaptive variability as it emerges during the swim-start. Variability is contextualized as having a functional role and operating across multiple levels of analysis: inter-subject (expert versus non-expert, inter-trial or intra-subject (through repetitions of the same movement, and inter-preference (preferred versus non-preferred technique. Regarding skill effects, we assume that swim-start expertise is distinct from swim stroke expertise. Highly skilled swim-starts are distinguished in terms of several factors: reaction time from the start signal to the impulse on the block, including the control and regulation of foot force and foot orientation during take-off; appropriate amount of glide time before leg kicking commences; effective transition from leg kicking to break-out of full swimming with arm stroking; overall maximal leg and arm propulsion and minimal water resistance; and minimized energy expenditure through streamlined body position. Swimmers who are less expert at the swim-start spend more time in this phase and would benefit from training designed to reduce: (i the time between reaction to the start signal and impulse on the block, and (ii the time in transition (i

Creatine supplementation and swim performance: a brief review.

Science.gov (United States)

Hopwood, Melissa J; Graham, Kenneth; Rooney, Kieron B

2006-03-01

Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle. Key PointsCreatine supplementation does not improve single sprint

1968 Listing of Swimming Pool Equipment.

Science.gov (United States)

National Sanitation Foundation, Ann Arbor, MI. Testing Lab.

An up-to-date listing of swimming pool equipment including--(1) companies authorized to display the National Sanitation Foundation seal of approval, (2) equipment listed as meeting NSF swimming pool equipment standards relating to diatomite type filters, (3) equipment listed as meeting NSF swimming pool equipment standard relating to sand type…

Supersymmetric Q-balls theory and cosmology

CERN Document Server

Kusenko, A

1999-01-01

MSSM predicts the existence of Q-balls, some of which can be entirely stable. Both stable and unstable Q-balls can play an important role in cosmology. In particular, Affleck-Dine baryogenesis can result in a copious production of stable baryonic Q-balls, which can presently exist as a form of dark matter.

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

Science.gov (United States)

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

2018-06-01

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

In situ swimming speed and swimming behaviour of fish feeding on the krill Meganyctiphanes norvegica

OpenAIRE

Onsrud, M. S. R.; Kaartvedt, Stein; Breien, M. T.

2005-01-01

In situ swimming speed and swimming behaviour of dielly migrating planktivorous fish were studied at a 120-m-deep location. Acoustic target tracking was performed using a hull-mounted transducer and submersible transducers located on the sea bottom and free hanging in the water column. The original data displayed a relationship between distance to transducer and swimming speed. A simplistic smoother applied during post-processing, appeared to break this relationship. Target tracki...

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

Science.gov (United States)

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

2008-01-01

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

Street children and political violence: a socio-demographic analysis of street children in Rwanda.

Science.gov (United States)

Veale, Angela; Donà, Giorgia

2003-03-01

The aims were: (1) to examine the profile of African street children and to assess the link between street children in Africa and political violence; (2) to undertake a systematic examination of causal factors of street children in postgenocide Rwanda; and (3) to situate this analysis in the context of the socio-cultural and political impact of the genocide on Rwandan communities. Observational mapping examined the profile and activities of Rwandan street children. Structured interviews were carried out with 290 children in four regional towns to obtain information on socio-demographic, familial, educational background, causal factors surrounding street life involvement, psychological well-being, and relationship to the street. Focus group discussions and key informant interviews examined the relationship between street children and the broader Rwandan society. Street children in Rwanda were predominantly adolescent boys, almost half of whom were homeless (42%), with a high proportion of orphaned children or children who had lost at least one parent. Two variables predicted homelessness: child's guardian and reason for being in street. Qualitative accounts of children conveyed the impact of death of family members, repatriation, imprisonment of parents, and poverty on their lives. The analysis highlighted the need for community based support for children in alternative guardianship care and for policies to support the reintegration of male youths in postconflict welfare strategies as prevention strategies for street migration.

Laboratory demonstration of ball lightning

International Nuclear Information System (INIS)

Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D

2004-01-01

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

Adolescent Hopefulness in Tanzania: Street Youth, Former Street Youth, and School Youth

Science.gov (United States)

Nalkur, Priya G.

2009-01-01

This study compares hope in street youth, former street youth, and school youth (aged 12-18) in Tanzania. Responding to Snyder's hope theory, the author argues that not only personal agency but also the stability of living context (street, shelter, home) shapes hopefulness. Employing qualitative and quantitative analyses, the author presents a…

Establishing zebrafish as a novel exercise model: swimming economy, swimming-enhanced growth and muscle growth marker gene expression.

Directory of Open Access Journals (Sweden)

Arjan P Palstra

Full Text Available BACKGROUND: Zebrafish has been largely accepted as a vertebrate multidisciplinary model but its usefulness as a model for exercise physiology has been hampered by the scarce knowledge on its swimming economy, optimal swimming speeds and cost of transport. Therefore, we have performed individual and group-wise swimming experiments to quantify swimming economy and to demonstrate the exercise effects on growth in adult zebrafish. METHODOLOGY/PRINCIPAL FINDINGS: Individual zebrafish (n = 10 were able to swim at a critical swimming speed (U(crit of 0.548±0.007 m s(-1 or 18.0 standard body lengths (BL s(-1. The optimal swimming speed (U(opt at which energetic efficiency is highest was 0.396±0.019 m s(-1 (13.0 BL s(-1 corresponding to 72.26±0.29% of U(crit. The cost of transport at optimal swimming speed (COT(opt was 25.23±4.03 µmol g(-1 m(-1. A group-wise experiment was conducted with zebrafish (n = 83 swimming at U(opt for 6 h day(-1 for 5 days week(-1 for 4 weeks vs. zebrafish (n = 84 that rested during this period. Swimming zebrafish increased their total body length by 5.6% and body weight by 41.1% as compared to resting fish. For the first time, a highly significant exercise-induced growth is demonstrated in adult zebrafish. Expression analysis of a set of muscle growth marker genes revealed clear regulatory roles in relation to swimming-enhanced growth for genes such as growth hormone receptor b (ghrb, insulin-like growth factor 1 receptor a (igf1ra, troponin C (stnnc, slow myosin heavy chain 1 (smyhc1, troponin I2 (tnni2, myosin heavy polypeptide 2 (myhz2 and myostatin (mstnb. CONCLUSIONS/SIGNIFICANCE: From the results of our study we can conclude that zebrafish can be used as an exercise model for enhanced growth, with implications in basic, biomedical and applied sciences, such as aquaculture.

Anisotropic swim stress in active matter with nematic order

Science.gov (United States)

Yan, Wen; Brady, John F.

2018-05-01

Active Brownian particles (ABPs) transmit a swim pressure {{{\\Pi }}}{{swim}}=n\\zeta {D}{{swim}} to the container boundaries, where ζ is the drag coefficient, D swim is the swim diffusivity and n is the uniform bulk number density far from the container walls. In this work we extend the notion of the isotropic swim pressure to the anisotropic tensorial swim stress {{\\boldsymbol{σ }}}{{swim}}=-n\\zeta {{\\boldsymbol{D}}}{{swim}}, which is related to the anisotropic swim diffusivity {{\\boldsymbol{D}}}{{swim}}. We demonstrate this relationship with ABPs that achieve nematic orientational order via a bulk external field. The anisotropic swim stress is obtained analytically for dilute ABPs in both 2D and 3D systems. The anisotropy, defined as the ratio of the maximum to the minimum of the three principal stresses, is shown to grow exponentially with the strength of the external field. We verify that the normal component of the anisotropic swim stress applies a pressure {{{\\Pi }}}{{swim}}=-({{\\boldsymbol{σ }}}{{swim}}\\cdot {\\boldsymbol{n}})\\cdot {\\boldsymbol{n}} on a wall with normal vector {\\boldsymbol{n}}, and, through Brownian dynamics simulations, this pressure is shown to be the force per unit area transmitted by the active particles. Since ABPs have no friction with a wall, the difference between the normal and tangential stress components—the normal stress difference—generates a net flow of ABPs along the wall, which is a generic property of active matter systems.

Swimming Pools and Molluscum Contagiosum

Science.gov (United States)

... Travelers’ Health: Smallpox & Other Orthopoxvirus-Associated Infections Poxvirus Swimming Pools Recommend on Facebook Tweet Share Compartir The ... often ask if molluscum virus can spread in swimming pools. There is also concern that it can ...

A systematic study of ball passing frequencies based on dynamic modeling of rolling ball bearings with localized surface defects

Science.gov (United States)

Niu, Linkai; Cao, Hongrui; He, Zhengjia; Li, Yamin

2015-11-01

Ball passing frequencies (BPFs) are very important features for condition monitoring and fault diagnosis of rolling ball bearings. The ball passing frequency on outer raceway (BPFO) and the ball passing frequency on inner raceway (BPFI) are usually calculated by two well-known kinematics equations. In this paper, a systematic study of BPFs of rolling ball bearings is carried out. A novel method for accurately calculating BPFs based on a complete dynamic model of rolling ball bearings with localized surface defects is proposed. In the used dynamic model, three-dimensional motions, relative slippage, cage effects and localized surface defects are all considered. Moreover, localized surface defects are modeled accurately with consideration of the finite size of the ball, the additional clearance due to material absence, and changes of contact force directions. The reasonability of the proposed method for the prediction of dynamic behaviors of actual ball bearings with localized surface defects and for the calculation of BPFs is discussed by investigating the motion characteristics of a ball when it rolls through a defect. Parametric investigation shows that the shaft speed, external loads, the friction coefficient, raceway groove curvature factors, the initial contact angle, and defect sizes have great effects on BPFs. For a loaded ball bearing, the combination of rolling and sliding in contact region occurs, and the BPFs calculated by simple kinematical relationships are inaccurate, especially for high speed, low external load, and large initial contact angle conditions where severe skidding occurs. The hypothesis that the percentage variation of the spacing between impulses in a defective ball bearing was about 1-2% reported in previous investigations can be satisfied only for the conditions where the skidding effect in a bearing is slight. Finally, the proposed method is verified with two experiments.

BALL - biochemical algorithms library 1.3

Directory of Open Access Journals (Sweden)

Stöckel Daniel

2010-10-01

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

Ball Screw Actuator Including a Stop with an Integral Guide

Science.gov (United States)

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

2015-01-01

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

Encapsulated Ball Bearings for Rotary Micro Machines

Science.gov (United States)

2007-01-01

occurrence as well as the overall tribological properties of the bearing mechanism. Firstly, the number of stainless steel balls influences not only the load...stacks.iop.org/JMM/17/S224 Abstract We report on the first encapsulated rotary ball bearing mechanism using silicon microfabrication and stainless steel balls...The method of capturing stainless steel balls within a silicon race to support a silicon rotor both axially and radially is developed for rotary micro

2012 Swimming Season Fact Sheets

Science.gov (United States)

To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

Experimental hydrodynamics of swimming in fishes

Science.gov (United States)

Tytell, Eric Daniel

2005-11-01

The great diversity of fish body shapes suggests that they have adapted to different selective pressures. For many fishes, the pressures include hydrodynamic demands: swimming efficiently or accelerating rapidly, for instance. However, the hydrodynamic advantages or disadvantages to specific morphologies are poorly understood. In particular, eels have been considered inefficient swimmers, but they migrate long distances without feeding, a task that requires efficient swimming. This dissertation, therefore, begins with an examination of the swimming hydrodynamics of American eels, Anguilla rostrata, at steady swimming speeds from 0.5 to 2 body lengths (L) per second and during accelerations from -1.4 to 1.3 L s -2. The final chapter examines the hydrodynamic effects of body shape directly by describing three-dimensional flow around swimming bluegill sunfish, Lepomis macrochirus. In all chapters, flow is quantified using digital particle image velocimetry, and simultaneous kinematics are measured from high-resolution digital video. The wake behind a swimming eel in the horizontal midline plane is described first. Rather than producing a wake with fluid jets angled backwards, like in fishes such as sunfish, eels have a wake with exclusively lateral jets. The lack of downstream momentum indicates that eels balance the axial forces of thrust and drag evenly over time and over their bodies, and therefore do not change axial fluid momentum. This even balance, present at all steady swimming speeds, is probably due to the relatively uniform body shape of eels. As eels accelerate, thrust exceeds drag, axial momentum increases, and the wake approaches that of other fishes. During steady swimming, though, the lack of axial momentum prevents direct efficiency estimation. The effect of body shape was examined directly by measuring flow in multiple transverse planes along the body of bluegill sunfish swimming at 1.2 L s-1. The dorsal and anal fin, neglected in many previous

Flight trajectory of a rotating golf ball with grooves

Science.gov (United States)

Baek, Moonheum; Kim, Jooha; Choi, Haecheon

2014-11-01

Dimples are known to reduce drag on a sphere by the amount of 50% as compared to a smooth surface. Despite the advantage of reducing drag, dimples deteriorate the putting accuracy owing to their sharp edges. To minimize this putting error but maintain the same flight distance, we have devised a grooved golf ball (called G ball hereafter) for several years. In this study, we modify the shape and pattern of grooves, and investigate the flow characteristics of the G ball by performing wind-tunnel experiments at the Reynolds numbers of 0 . 5 ×105 - 2 . 5 ×105 and the spin ratios (ratio of surface velocity to the free-stream velocity) of 0 - 0.6 that include the real golf-ball velocity and rotational speed. We measure the drag and lift forces on the rotating G ball and compare them with those of a smooth ball and two well-known dimpled balls. The lift-to-drag ratio of the G ball is much higher than that of a smooth ball and is in between those of the two dimpled balls. The trajectories of flying golf balls are computed. The flight distance of G ball is almost the same as that of one dimpled ball but slightly shorter than that of the other dimpled ball. The fluid-dynamic aspects of these differences will be discussed at the talk. Supported by 2011-0028032, 2014M3C1B1033980.

How does gravity save or kill Q-balls?

International Nuclear Information System (INIS)

Tamaki, Takashi; Sakai, Nobuyuki

2011-01-01

We explore stability of gravitating Q-balls with potential V 4 (φ)=(m 2 /2)φ 2 -λφ 4 +(φ 6 /M 2 ) via catastrophe theory, as an extension of our previous work on Q-balls with potential V 3 (φ)=(m 2 /2)φ 2 -μφ 3 +λφ 4 . In flat spacetime Q-balls with V 4 in the thick-wall limit are unstable and there is a minimum charge Q min , where Q-balls with Q min are nonexistent. If we take self-gravity into account, on the other hand, there exist stable Q-balls with arbitrarily small charge, no matter how weak gravity is. That is, gravity saves Q-balls with small charge. We also show how stability of Q-balls changes as gravity becomes strong.

Kinematics of swimming and thrust production during powerstroking bouts of the swim frenzy in green turtle hatchlings

Directory of Open Access Journals (Sweden)

David T. Booth

2014-09-01

Full Text Available Hatchling sea turtles emerge from nests, crawl down the beach and enter the sea where they typically enter a stereotypical hyperactive swimming frenzy. During this swim the front flippers are moved up and down in a flapping motion and are the primary source of thrust production. I used high-speed video linked with simultaneous measurement of thrust production in tethered hatchlings, along with high-speed video of free swimming hatchlings swimming at different water speeds in a swim flume to investigate the links between kinematics of front flipper movement, thrust production and swimming speed. In particular I tested the hypotheses that (1 increased swimming speed is achieved through an increased stroke rate; (2 force produced per stroke is proportional to stroke amplitude, (3 that forward thrust is produced during both the down and up phases of stroking; and (4 that peak thrust is produced towards the end of the downstroke cycle. Front flipper stroke rate was independent of water speed refuting the hypothesis that swimming speed is increased by increasing stroke rate. Instead differences in swimming speed were caused by a combination of varying flipper amplitude and the proportion of time spent powerstroking. Peak thrust produced per stroke varied within and between bouts of powerstroking, and these peaks in thrust were correlated with both flipper amplitude and flipper angular momentum during the downstroke supporting the hypothesis that stroke force is a function of stroke amplitude. Two distinct thrust production patterns were identified, monophasic in which a single peak in thrust was recorded during the later stages of the downstroke, and biphasic in which a small peak in thrust was recorded at the very end of the upstroke and this followed by a large peak in thrust during the later stages of the downstroke. The biphasic cycle occurs in ∼20% of hatchlings when they first started swimming, but disappeared after one to two hours of

Streets? Where We're Going, We Don't Need Streets

Science.gov (United States)

Bailey, J.

2017-12-01

In 2007 Google Street View started as a project to provide 360-degree imagery along streets, but in the decade since has evolved into a platform through which to explore everywhere from the slope of everest, to the middle of the Amazon rainforest to under the ocean. As camera technology has evolved it has also become a tool for ground truthing maps, and provided scientific observations, storytelling and education. The Google Street View "special collects" team has undertaken increasingly more challenging projects across 80+ countries and every continent. All of which culminated in possibly the most ambitious collection yet, the capture of Street View on board the International Space Station. Learn about the preparation and obstacles behind this and other special collects. Explore these datasets through both Google Earth and Google Expeditions VR, an educational tool to take students on virtual field trips using 360 degree imagery.

Prey capture by freely swimming flagellates

Science.gov (United States)

Andersen, Anders; Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas

2017-11-01

Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. Here, we explore the dependence of swimming kinematics and prey clearance rate on flagellar arrangement and determine optimal flagellar arrangements and essential trade-offs. To describe near-cell flows around freely swimming flagellates we consider a model in which the cell is represented by a no-slip sphere and each flagellum by a point force. For uniflagellates pulled by a single flagellum the model suggests that a long flagellum favors fast swimming, whereas high clearance rate is favored by a very short flagellum. For biflagellates with both a longitudinal and a transversal flagellum we explore the helical swimming kinematics and the prey capture sites. We compare our predictions with observations of swimming kinematics, prey capture, and flows around common marine flagellates. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

Experimental research on ball lightning

International Nuclear Information System (INIS)

Ofuruton, H.; Ohtsuki, Y.H.

1990-01-01

Experiments on producing ball lightning were made with discharge in flammable gas and/or aerosol. A long lifetime (2 s) ball lightning was observed in 2.7 % ethane and 100 cm 3 cotton fibers, and in 1.5 % methane and 1.9 % ethane

Geneva 24 hours swim

CERN Document Server

2003-01-01

The 18th edition of the Geneva 24 hours swim competition will take place at the Vernets Swimming Pool on the 4th and 5th of October. More information and the results of previous years are given at: http://www.carouge-natation.com/24_heures/home_24_heures.htm Last year, CERN obtained first position in the inter-company category with a total of 152.3 kms swam by 45 participants. We are counting on your support to repeat this excellent performance this year. For those who would like to train, the Livron swimming pool in Meyrin is open as from Monday the 8th September. For further information please do not hesitate to contact us. Gino de Bilio and Catherine Delamare

Geneva 24 Hours Swim

CERN Document Server

2003-01-01

The 18th edition of the Geneva 24 hours swim competition will take place at the Vernets Swimming Pool on the 4th and 5th of October. More information and the results of previous years are given at: http://www.carouge-natation.com/24_heures/home_24_heures.htm Last year, CERN obtained first position in the inter-company category with a total of 152.3 kms swam by 45 participants. We are counting on your support to repeat this excellent performance this year. For those who would like to train, the Livron swimming pool in Meyrin is open as from Monday the 8th September. For further information please do not hesitate to contact us. Gino de Bilio and Catherine Delamare

Thermal Comfort Assessment in The Open Space in Bandung Case Study Dago Street and Riau Street

Science.gov (United States)

Sugangga, M.; Janesonia, K. I.; Illiyin, D. F.; Donny Koerniawan, M.

2018-05-01

Bandung’s temperature has been higher since last years. This phenomenon affects the level of thermal comfort in open space. One indicator that determines the thermal comfort level is the type of activity performed by the open space user. Riau Street and Dago Street are corridors that are often used by the people for strolling, jogging, shopping. Dago Street has special event every Sunday namely car free day. Both corridors have different orientation; Dago Street is North to South corridor while Riau Street’s is West to East. The goal of the study is to compare people’s perception of thermal comfort in both corridors. This research uses two methods, namely qualitative method and quantitative method. Based on the results of qualitative analysis found that the thermal conditions in Dago Street more comfortable than the Riau Street. The result of quantitative analysis found that the average PET (thermal comfort indices) value of Dago Street was at 27.5 °C PET and Riau Street 28.6 °C PET. Dago Street is considered more convenient because it has a lower PET value than Riau Street. The people perception of thermal comfort is very important to start the steps for designing the orientation of street in urban design.

Potential reductions of street solids and phosphorus in urban watersheds from street cleaning, Cambridge, Massachusetts, 2009-11

Science.gov (United States)

Sorenson, Jason R.

2013-01-01

Material accumulating and washing off urban street surfaces and ultimately into stormwater drainage systems represents a substantial nonpoint source of solids, phosphorus, and other constituent loading to waterways in urban areas. Cost and lack of usable space limit the type and number of structural stormwater source controls available to municipalities and other public managers. Non-structural source controls such as street cleaning are commonly used by cities and towns for construction, maintenance and aesthetics, and may reduce contaminant loading to waterways. Effectiveness of street cleaning is highly variable and potential improvements to water quality are not fully understood. In 2009, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, the U.S. Environmental Protection Agency, and the city of Cambridge, Massachusetts, and initiated a study to better understand the physical and chemical nature of the organic and inorganic solid material on street surfaces, evaluate the performance of a street cleaner at removing street solids, and make use of the Source Loading and Management Model (SLAMM) to estimate potential reductions in solid and phosphorus loading to the lower Charles River from various street-cleaning technologies and frequencies. Average yield of material on streets collected between May and December 2010, was determined to be about 740 pounds per curb-mile on streets in multifamily land use and about 522 pounds per curb-mile on commercial land-use streets. At the end-of-winter in March 2011, about 2,609 and 4,788 pounds per curb-mile on average were collected from streets in multifamily and commercial land-use types, respectively. About 86 percent of the total street-solid yield from multifamily and commercial land-use streets was greater than or equal to 0.125 millimeters in diameter (or very fine sand). Observations of street-solid distribution across the entire street width indicated that as

Optimal swimming strategies in mate searching pelagic copepods

DEFF Research Database (Denmark)

Kiørboe, Thomas

2008-01-01

Male copepods must swim to find females, but swimming increases the risk of meeting predators and is expensive in terms of energy expenditure. Here I address the trade-offs between gains and risks and the question of how much and how fast to swim using simple models that optimise the number...... of lifetime mate encounters. Radically different swimming strategies are predicted for different feeding behaviours, and these predictions are tested experimentally using representative species. In general, male swimming speeds and the difference in swimming speeds between the genders are predicted...... and observed to increase with increasing conflict between mate searching and feeding. It is high in ambush feeders, where searching (swimming) and feeding are mutually exclusive and low in species, where the matured males do not feed at all. Ambush feeding males alternate between stationary ambush feeding...

Swimming efficiency in a shear-thinning fluid

Science.gov (United States)

Nganguia, Herve; Pietrzyk, Kyle; Pak, On Shun

2017-12-01

Micro-organisms expend energy moving through complex media. While propulsion speed is an important property of locomotion, efficiency is another factor that may determine the swimming gait adopted by a micro-organism in order to locomote in an energetically favorable manner. The efficiency of swimming in a Newtonian fluid is well characterized for different biological and artificial swimmers. However, these swimmers often encounter biological fluids displaying shear-thinning viscosities. Little is known about how this nonlinear rheology influences the efficiency of locomotion. Does the shear-thinning rheology render swimming more efficient or less? How does the swimming efficiency depend on the propulsion mechanism of a swimmer and rheological properties of the surrounding shear-thinning fluid? In this work, we address these fundamental questions on the efficiency of locomotion in a shear-thinning fluid by considering the squirmer model as a general locomotion model to represent different types of swimmers. Our analysis reveals how the choice of surface velocity distribution on a squirmer may reduce or enhance the swimming efficiency. We determine optimal shear rates at which the swimming efficiency can be substantially enhanced compared with the Newtonian case. The nontrivial variations of swimming efficiency prompt questions on how micro-organisms may tune their swimming gaits to exploit the shear-thinning rheology. The findings also provide insights into how artificial swimmers should be designed to move through complex media efficiently.

Q-balls in flat potentials

International Nuclear Information System (INIS)

Copeland, Edmund J.; Tsumagari, Mitsuo I.

2009-01-01

We study the classical and absolute stability of Q-balls in scalar field theories with flat potentials arising in both gravity-mediated and gauge-mediated models. We show that the associated Q-matter formed in gravity-mediated potentials can be stable against decay into their own free particles as long as the coupling constant of the nonrenormalizable term is small, and that all of the possible three-dimensional Q-ball configurations are classically stable against linear fluctuations. Three-dimensional gauge-mediated Q-balls can be absolutely stable in the thin-wall limit, but are completely unstable in the thick-wall limit.

Free Swimming in Ground Effect

Science.gov (United States)

Cochran-Carney, Jackson; Wagenhoffer, Nathan; Zeyghami, Samane; Moored, Keith

2017-11-01

A free-swimming potential flow analysis of unsteady ground effect is conducted for two-dimensional airfoils via a method of images. The foils undergo a pure pitching motion about their leading edge, and the positions of the body in the streamwise and cross-stream directions are determined by the equations of motion of the body. It is shown that the unconstrained swimmer is attracted to a time-averaged position that is mediated by the flow interaction with the ground. The robustness of this fluid-mediated equilibrium position is probed by varying the non-dimensional mass, initial conditions and kinematic parameters of motion. Comparisons to the foil's fixed-motion counterpart are also made to pinpoint the effect that free swimming near the ground has on wake structures and the fluid-mediated forces over time. Optimal swimming regimes for near-boundary swimming are determined by examining asymmetric motions.

Undulatory fish swimming : from muscles to flow

NARCIS (Netherlands)

Müller, U.K.; Leeuwen, van J.L.

2006-01-01

Undulatory swimming is employed by many fish for routine swimming and extended sprints. In this biomechanical review, we address two questions: (i) how the fish's axial muscles power swimming; and (ii) how the fish's body and fins generate thrust. Fish have adapted the morphology of their axial

Quality versus Quantity Debate in Swimming: Perceptions and Training Practices of Expert Swimming Coaches.

Science.gov (United States)

Nugent, Frank J; Comyns, Thomas M; Warrington, Giles D

2017-06-01

The debate over low-volume, high-intensity training versus high-volume, low-intensity training, commonly known as Quality versus Quantity, respectively, is a frequent topic of discussion among swimming coaches and academics. The aim of this study was to explore expert coaches' perceptions of quality and quantity coaching philosophies in competitive swimming and to investigate their current training practices. A purposeful sample of 11 expert swimming coaches was recruited for this study. The study was a mixed methods design and involved each coach participating in 1 semi-structured interview and completing 1 closed-ended questionnaire. The main findings of this study were that coaches felt quality training programmes would lead to short term results for youth swimmers, but were in many cases more appropriate for senior swimmers. The coaches suggested that quantity training programmes built an aerobic base for youth swimmers, promoted technical development through a focus on slower swimming and helped to enhance recovery from training or competition. However, the coaches continuously suggested that quantity training programmes must be performed with good technique and they felt this was a misunderstood element. This study was a critical step towards gaining a richer and broader understanding on the debate over Quality versus Quantity training from an expert swimming coaches' perspective which was not currently available in the research literature.

Quality Versus Quantity Debate in Swimming: Perceptions and Training Practices of Expert Swimming Coaches

Directory of Open Access Journals (Sweden)

Nugent Frank J.

2017-06-01

Full Text Available The debate over low-volume, high-intensity training versus high-volume, low-intensity training, commonly known as Quality versus Quantity, respectively, is a frequent topic of discussion among swimming coaches and academics. The aim of this study was to explore expert coaches’ perceptions of quality and quantity coaching philosophies in competitive swimming and to investigate their current training practices. A purposeful sample of 11 expert swimming coaches was recruited for this study. The study was a mixed methods design and involved each coach participating in 1 semi-structured interview and completing 1 closed-ended questionnaire. The main findings of this study were that coaches felt quality training programmes would lead to short term results for youth swimmers, but were in many cases more appropriate for senior swimmers. The coaches suggested that quantity training programmes built an aerobic base for youth swimmers, promoted technical development through a focus on slower swimming and helped to enhance recovery from training or competition. However, the coaches continuously suggested that quantity training programmes must be performed with good technique and they felt this was a misunderstood element. This study was a critical step towards gaining a richer and broader understanding on the debate over Quality versus Quantity training from an expert swimming coaches’ perspective which was not currently available in the research literature.

LHC gets the ball rolling

CERN Multimedia

2007-01-01

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

Wall Street som kreationistisk forkynder

DEFF Research Database (Denmark)

Ekman, Susanne

2016-01-01

Artiklen gennemgår Karen Hos etnografi om Wall Street: "Liquidated: An ethnography of Wall Street" set i lyset af den offentlige debat vedrørende Goldman Sachs opkøb af Dong......Artiklen gennemgår Karen Hos etnografi om Wall Street: "Liquidated: An ethnography of Wall Street" set i lyset af den offentlige debat vedrørende Goldman Sachs opkøb af Dong...

Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata)

DEFF Research Database (Denmark)

Svendsen, Jon Christian; Banet, Amanda I.; Christensen, Rune Haubo Bojesen

2013-01-01

by the total body mass. Results showed that the metabolic rate increased curvilinearly with swimming speed. The slope of the relationship was used as an index of swimming cost. There was no evidence that reproductive traits correlated with swimming cost, MO2std or Ucrit. In contrast, data revealed strong...... swimming and pectoral fin movement over a wide speed range, presumably to support swimming stability and control, is an inefficient swimming behaviour. Finally, transition to burst-assisted swimming was associated with an increase in aerobic metabolic rate. Our study highlights factors other than swimming...

Static Load Distribution in Ball Bearings

Science.gov (United States)

Ricci, Mario

2010-01-01

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

Multifractal properties of ball milling dynamics

Energy Technology Data Exchange (ETDEWEB)

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

2014-06-15

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

Krill (Meganyctiphanes norvegica) swim faster at night

KAUST Repository

Klevjer, Thor A.

2011-05-01

Krill are key members in marine food webs, and measurement of swimming speed is vital to assess their bioenergetic budgets, feeding, and encounters with predators. We document a consistent and marked diel signal in swimming speed of krill in their natural habitat that is not related to diel vertical migration. The results were obtained using a bottom-mounted, upward-looking echo sounder at 150-m depth in the Oslofjord, Norway, spanning 5 months from late autumn to spring at a temporal resolution of ~1–2 records s−1. Swimming speed was assessed using acoustic target tracking of individual krill. At the start of the registration period, both daytime and nocturnal average swimming speeds of Meganyctiphanes norvegica were ~ 3.5 cm s−1 (~ 1 body lengths ([bl] s−1) in waters with oxygen concentrations of ~ 15–20% O2 saturation. Following intrusion of more oxygenated water, nocturnal average swimming speeds increased to ~ 10 cm s−1 (~ 3 bl s−1), i.e., more than double that of daytime swimming speeds in the same period. We hypothesize that krill activity during the first period was limited by oxygen, and the enhanced swimming at night subsequent to the water renewal is due to increased feeding activity under lessened danger of predation in darkness.

Krill (Meganyctiphanes norvegica) swim faster at night

KAUST Repository

Klevjer, Thor A.; Kaartvedt, Stein

2011-01-01

Krill are key members in marine food webs, and measurement of swimming speed is vital to assess their bioenergetic budgets, feeding, and encounters with predators. We document a consistent and marked diel signal in swimming speed of krill in their natural habitat that is not related to diel vertical migration. The results were obtained using a bottom-mounted, upward-looking echo sounder at 150-m depth in the Oslofjord, Norway, spanning 5 months from late autumn to spring at a temporal resolution of ~1–2 records s−1. Swimming speed was assessed using acoustic target tracking of individual krill. At the start of the registration period, both daytime and nocturnal average swimming speeds of Meganyctiphanes norvegica were ~ 3.5 cm s−1 (~ 1 body lengths ([bl] s−1) in waters with oxygen concentrations of ~ 15–20% O2 saturation. Following intrusion of more oxygenated water, nocturnal average swimming speeds increased to ~ 10 cm s−1 (~ 3 bl s−1), i.e., more than double that of daytime swimming speeds in the same period. We hypothesize that krill activity during the first period was limited by oxygen, and the enhanced swimming at night subsequent to the water renewal is due to increased feeding activity under lessened danger of predation in darkness.

Surface Waters Information Management System (SWIMS)

Data.gov (United States)

Kansas Data Access and Support Center — The Surface Waters Information Management System (SWIMS) has been designed to meet multi-agency hydrologic database needs for Kansas. The SWIMS project was supported...

Swimming in an Unsteady World

Science.gov (United States)

Koehl, M. A. R.

2016-02-01

When animals swim in marine habitats, the water through which they move is usually flowing. Therefore, an important part of understanding the physics of how animals swim in nature is determining how they interact with the fluctuating turbulent water currents in their environment. The research systems we have been using to address this question are microscopic marine animals swimming in turbulent, wavy water flow over spatially-complex communities of organisms growing on surfaces. Field measurements of water motion were used to design realistic turbulent flow in a laboratory wave-flume over different substrata, particle-image velocimetry was used to measure fine-scale, rapidly-varying water velocity vector fields, and planar laser-induced fluorescence was used to measure concentrations of chemical cues from the substratum. We used individual-based models of small animals swimming in this unsteady flow to determine how their trajectories and contacts with substrata were affected by their locomotion through the water, rotation by local shear, response to odors, and transport by ambient flow. We found that the shears, accelerations, and odor concentrations encountered by small swimmers fluctuate rapidly, with peaks much higher than mean values lasting fractions of a second. We identified ways in which the behavior of small, weak swimmers can bias how they are transported by ambient flow (e.g. sinking during brief encounters with shear or odor enhances settlement onto substrata below, whereas constant swimming enhances contact with surfaces above or beside larvae). Although microscopic organisms swim slowly relative to ambient water flow, their locomotory behavior in response to the rapidly-fluctuating shears and odors they encounter can affect where they are transported by ambient water movement.

Aerodynamic drag of modern soccer balls.

Science.gov (United States)

Asai, Takeshi; Seo, Kazuya

2013-12-01

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

Swimming and other activities: applied aspects of fish swimming performance

Science.gov (United States)

Castro-Santos, Theodore R.; Farrell, A.P.

2011-01-01

Human activities such as hydropower development, water withdrawals, and commercial fisheries often put fish species at risk. Engineered solutions designed to protect species or their life stages are frequently based on assumptions about swimming performance and behaviors. In many cases, however, the appropriate data to support these designs are either unavailable or misapplied. This article provides an overview of the state of knowledge of fish swimming performance – where the data come from and how they are applied – identifying both gaps in knowledge and common errors in application, with guidance on how to avoid repeating mistakes, as well as suggestions for further study.

On the formation of ball lightning

International Nuclear Information System (INIS)

Silberg, P.A.

1981-01-01

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

RACE, CODE OF THE STREET, AND VIOLENT DELINQUENCY: A MULTILEVEL INVESTIGATION OF NEIGHBORHOOD STREET CULTURE AND INDIVIDUAL NORMS OF VIOLENCE*

Science.gov (United States)

Stewart, Eric A.; Simons, Ronald L.

2011-01-01

The study outlined in this article drew on Elijah Anderson’s (1999) code of the street perspective to examine the impact of neighborhood street culture on violent delinquency. Using data from more than 700 African American adolescents, we examined 1) whether neighborhood street culture predicts adolescent violence above and beyond an adolescent’s own street code values and 2) whether neighborhood street culture moderates individual-level street code values on adolescent violence. Consistent with Anderson’s hypotheses, neighborhood street culture significantly predicts violent delinquency independent of individual-level street code effects. Additionally, neighborhood street culture moderates individual-level street code values on violence in neighborhoods where the street culture is widespread. In particular, the effect of street code values on violence is enhanced in neighborhoods where the street culture is endorsed widely. PMID:21666759

Analysis of Sport Nutrition and Diet for Swimming Athletes

OpenAIRE

Jun An

2014-01-01

This current study analyzed nutrition and dietary structure of swimming athletes to clarify issues in nutrition and dietary structure of swimming athletes, based on which we designed achievable nutrition and diet strategies to equip the swimming athletes with the tools to achieve an adequate sport nutrition which helps them improve results. Firstly, we collected literatures about nutrition and diet of swimming athletes. Secondly, 40 swimming athletes were assigned to the test group and the co...

THE IMPACT OF TECHNICAL ABILITY TO SWIMMING PERFORMANCE OF THE MIXED SWIMMING AT 100m IN COLLEGE FASTO

Directory of Open Access Journals (Sweden)

Elvira Beganović

2011-08-01

Full Text Available The aim of this study was to determine the impact of technical ability to swim (the starting point, the techniques and turns, within each of these techniques of swimming (freestyle, backstroke, breaststroke and butterfly marked as input or predictor variables, the performance of mixed swimming in the 100m, marked as output or criterion variable. The study was conducted on a sample of 31 students, females, aged from 20-24 years, with the help of the testing (assessment, technical skills of swimming (start, the techniques and turns: OCJKSTR, OCJKTEH, OCJKOKR, OCJLSTR, OCJLTEH, OCJLOKR, OCJPSTR, OCJPTEH, OCJPOKR, OCJDSTR, OCJDTEH, OCJDOKR and mixed swimming in the 100m (OCJPM100, the following order: butterfly, back, breaststroke, freestyle. Analyzing the presented results of regression analysis can be stated that after testing (assessment of all predictor system statistically the most significant impact on the criterion variable had the following variables: assessment techniques freestyle (OCJKTEH, evaluation of starting breast stroke (OCJPSTR and assessment of breast stroke turns (OCJPOKR.

(Important hygienic aspects for swimming pools (author's transl))

Energy Technology Data Exchange (ETDEWEB)

Somosi, G

1981-01-01

The major epidemics which occurred in Hungary and originated from water in swimming pools are reported. The difficulties encountered in producing epidemiological evidence and in monitoring infections originating from water in swimming pools are mentioned. The possibilities of controlling the water quality in swimming pools and of preventing infections are discussed. Reference is made to the existing bacteriological limit values in Hungary to be observed in the recirculation of water in swimming pools.

Exercise-training intervention studies in competitive swimming.

Science.gov (United States)

Aspenes, Stian Thoresen; Karlsen, Trine

2012-06-01

Competitive swimming has a long history and is currently one of the largest Olympic sports, with 16 pool events. Several aspects separate swimming from most other sports such as (i) the prone position; (ii) simultaneous use of arms and legs for propulsion; (iii) water immersion (i.e. hydrostatic pressure on thorax and controlled respiration); (iv) propulsive forces that are applied against a fluctuant element; and (v) minimal influence of equipment on performance. Competitive swimmers are suggested to have specific anthropometrical features compared with other athletes, but are nevertheless dependent on physiological adaptations to enhance their performance. Swimmers thus engage in large volumes of training in the pool and on dry land. Strength training of various forms is widely used, and the energetic systems are addressed by aerobic and anaerobic swimming training. The aim of the current review was to report results from controlled exercise training trials within competitive swimming. From a structured literature search we found 17 controlled intervention studies that covered strength or resistance training, assisted sprint swimming, arms-only training, leg-kick training, respiratory muscle training, training the energy delivery systems and combined interventions across the aforementioned categories. Nine of the included studies were randomized controlled trials. Among the included studies we found indications that heavy strength training on dry land (one to five repetitions maximum with pull-downs for three sets with maximal effort in the concentric phase) or sprint swimming with resistance towards propulsion (maximal pushing with the arms against fixed points or pulling a perforated bowl) may be efficient for enhanced performance, and may also possibly have positive effects on stroke mechanics. The largest effect size (ES) on swimming performance was found in 50 m freestyle after a dry-land strength training regimen of maximum six repetitions across three

Simulating the impacts of on-street vehicle parking on traffic operations on urban streets using cellular automation

Science.gov (United States)

Chen, Jingxu; Li, Zhibin; Jiang, Hang; Zhu, Senlai; Wang, Wei

2017-02-01

In recent years, many bicycle lanes on urban streets are replaced with vehicle parking places. Spaces for bicycle riding are reduced, resulting in changes in bicycle and vehicle operational features. The objective of this study is to estimate the impacts of on-street parking on heterogeneous traffic operation on urban streets. A cellular automaton (CA) model is developed and calibrated to simulate bicycle lane-changing on streets with on-street parking. Two types of street segments with different bicycle lane width are considered. From the simulation, two types of conflicts between bicycles and vehicles are identified which are frictional conflicts and blocking conflicts. Factors affecting the frequency of conflicts are also identified. Based on the results, vehicle delay is estimated for various traffic situations considering the range of occupancy levels for on-street parking. Later, a numerical network example is analyzed to estimate the network impact of on-street parking on traffic assignment and operation. Findings of the study are helpful to policies and design regarding on-street vehicle parking to improve the efficiency of traffic operations.

Comparative jet wake structure and swimming performance of salps.

Science.gov (United States)

Sutherland, Kelly R; Madin, Laurence P

2010-09-01

Salps are barrel-shaped marine invertebrates that swim by jet propulsion. Morphological variations among species and life-cycle stages are accompanied by differences in swimming mode. The goal of this investigation was to compare propulsive jet wakes and swimming performance variables among morphologically distinct salp species (Pegea confoederata, Weelia (Salpa) cylindrica, Cyclosalpa sp.) and relate swimming patterns to ecological function. Using a combination of in situ dye visualization and particle image velocimetry (PIV) measurements, we describe properties of the jet wake and swimming performance variables including thrust, drag and propulsive efficiency. Locomotion by all species investigated was achieved via vortex ring propulsion. The slow-swimming P. confoederata produced the highest weight-specific thrust (T=53 N kg(-1)) and swam with the highest whole-cycle propulsive efficiency (eta(wc)=55%). The fast-swimming W. cylindrica had the most streamlined body shape but produced an intermediate weight-specific thrust (T=30 N kg(-1)) and swam with an intermediate whole-cycle propulsive efficiency (eta(wc)=52%). Weak swimming performance variables in the slow-swimming C. affinis, including the lowest weight-specific thrust (T=25 N kg(-1)) and lowest whole-cycle propulsive efficiency (eta(wc)=47%), may be compensated by low energetic requirements. Swimming performance variables are considered in the context of ecological roles and evolutionary relationships.

Apparatus Would Measure Temperatures Of Ball Bearings

Science.gov (United States)

Gibson, John C.; Fredricks, Thomas H.

1995-01-01

Rig for testing ball bearings under radial and axial loads and measuring surface temperatures undergoing development. Includes extensible thermocouples: by means of bellows as longitudinal positioners, thermocouples driven into contact with bearing balls to sense temperatures immediately after test run. Not necessary to disassemble rig or to section balls to obtain indirect indications of maximum temperatures reached. Thermocouple measurements indicate temperatures better than temperature-sensitive paints.

EFFECTIVENESS OF DOUBLE WASH SWIM-UP VERSUS DOUBLE DENSITY GRADIENT SWIM-UP TECHNIQUE OF SPERM PREPARATION IN IN VITRO FERTILISATION

Directory of Open Access Journals (Sweden)

Srinivas Sangisapu

2017-10-01

Full Text Available BACKGROUND Recovery of optimum number of good quality of spermatozoa is an important component of In Vitro Fertilisation (IVF. This is achieved by sperm preparation methods involving separation and recovery of capacitated sperms. Double Wash Swim-up (DWSU and Double Density Gradient Swim-up (DDGSU are two most accepted methods. Cochrane systematic review (2007 finds no clear benefit of one method over the other in Intrauterine Insemination (IUI. Systematic review on effectiveness of these preparations in IVF is lacking. Effectiveness is generally assessed in terms recovery rates of the sperms. Capability of successful fertilisation of good quality oocytes should ideally be the functional endpoint for evaluating effectiveness of sperm preparation methods. The aim of the study is to1. Compare the successful fertilisation rates of oocytes inseminated by semen preparation of Double Wash Swim-up (DWSU vis-a-vis by Double Density Gradient Swim-up (DDGSU method. 2. Evaluate the effectiveness of fertilisation of oocytes by Double Wash Swim-up method (DWSU vis-a-vis Double Density Gradient Swim-up (DDGSU method. MATERIALS AND METHODS A retrospective cohort study was conducted on infertile couples undergoing IVF from June 2014 to June 2017 at an ART Centre of a tertiary care hospital. The male partners were normozoospermic and female partners were normoresponsive to controlled ovarian stimulation and oocyte retrieval. RESULTS 70 male partners were subjected to double wash swim-up and 64 underwent double density gradient swim-up preparation. 1296 good quality oocytes were retrieved in their respective female partners. 452 (61% out of 742 oocytes were successfully fertilised after insemination by semen prepared by DWSU method. 378 (68% oocytes out of 554 were fertilised by insemination with semen prepared by DDGSU method. There seems to be strong association (RR=1.12 of fertilisation success with oocytes exposed to semen prepared by Double Density Gradient

Ball Screw Actuator Including an Axial Soft Stop

Science.gov (United States)

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

2016-01-01

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

Berkeley High-Resolution Ball

International Nuclear Information System (INIS)

Diamond, R.M.

1984-10-01

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

Critical evaluation of oxygen-uptake assessment in swimming.

Science.gov (United States)

Sousa, Ana; Figueiredo, Pedro; Pendergast, David; Kjendlie, Per-Ludvik; Vilas-Boas, João P; Fernandes, Ricardo J

2014-03-01

Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO2) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central-O2 delivery and transportation to the working muscles-or peripheral factors-O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers' behavior in competition and to develop efficient training programs.

Swimming and feeding of mixotrophic biflagellates

DEFF Research Database (Denmark)

Dölger, Julia; Nielsen, Lasse Tor; Kiørboe, Thomas

2017-01-01

Many unicellular flagellates are mixotrophic and access resources through both photosynthesis and prey capture. Their fitness depends on those processes as well as on swimming and predator avoidance. How does the flagellar arrangement and beat pattern of the flagellate affect swimming speed...... with variable position next to a no-slip sphere. Utilizing the observations and the model we find that puller force arrangements favour feeding, whereas equatorial force arrangements favour fast and quiet swimming. We determine the capture rates of both passive and motile prey, and we show that the flow...

Street-art

OpenAIRE

Rybnikářová, Klára

2009-01-01

This thesis is concerned with the street-art and graffiti phenomenon. The theoretical research is focused on presenting the essence and character of this art style, while also watching it from socio-cultural point of view and observing it in context of art history. The theoretical study is followed by the didactical part of thesis, where I present possibilities of using the street-art theme in art education programs in the school setting. My thesis is concluded with a discussion of a practica...

Modeling and Analyzing the Slipping of the Ball Screw

Directory of Open Access Journals (Sweden)

Nannan Xu

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

Kick, Stroke and Swim: Complement Your Swimming Program by Engaging the Whole Body on Dry Land and in the Pool

Science.gov (United States)

Flynn, Susan; Duell, Kelly; Dehaven, Carole; Heidorn, Brent

2017-01-01

The Kick, Stroke and Swim (KSS) program can be used to engage students in swimming-skill acquisition and fitness training using a variety of modalities, strategies and techniques on dry land. Practicing swim strokes and techniques on land gives all levels of swimmers--from beginner to competitive--a kinesthetic awareness of the individual…

Citygml and the Streets of New York - a Proposal for Detailed Street Space Modelling

Science.gov (United States)

Beil, C.; Kolbe, T. H.

2017-10-01

Three-dimensional semantic city models are increasingly used for the analysis of large urban areas. Until now the focus has mostly been on buildings. Nonetheless many applications could also benefit from detailed models of public street space for further analysis. However, there are only few guidelines for representing roads within city models. Therefore, related standards dealing with street modelling are examined and discussed. Nearly all street representations are based on linear abstractions. However, there are many use cases that require or would benefit from the detailed geometrical and semantic representation of street space. A variety of potential applications for detailed street space models are presented. Subsequently, based on related standards as well as on user requirements, a concept for a CityGML-compliant representation of street space in multiple levels of detail is developed. In the course of this process, the CityGML Transportation model of the currently valid OGC standard CityGML2.0 is examined to discover possibilities for further developments. Moreover, a number of improvements are presented. Finally, based on open data sources, the proposed concept is implemented within a semantic 3D city model of New York City generating a detailed 3D street space model for the entire city. As a result, 11 thematic classes, such as roadbeds, sidewalks or traffic islands are generated and enriched with a large number of thematic attributes.

Street Children as M arginal People: The Relationship between Life History and Social Networks on the Street

OpenAIRE

SUCHARITKUL, Juthathip

2007-01-01

This paper assumes that street children are victims of socioeconomic development policy. As a consequence of the street life experience, children are labeled as street children by society and their way of their life is different from ordinary children, thus pushing them to become marginalized people. The purpose of this paper is to examine the Street Children phenomenon, and especially to study the relationship between their life history and personal networks on the street. The focus is to...

Transitions between three swimming gaits in Paramecium escape.

Science.gov (United States)

Hamel, Amandine; Fisch, Cathy; Combettes, Laurent; Dupuis-Williams, Pascale; Baroud, Charles N

2011-05-03

Paramecium and other protists are able to swim at velocities reaching several times their body size per second by beating their cilia in an organized fashion. The cilia beat in an asymmetric stroke, which breaks the time reversal symmetry of small scale flows. Here we show that Paramecium uses three different swimming gaits to escape from an aggression, applied in the form of a focused laser heating. For a weak aggression, normal swimming is sufficient and produces a steady swimming velocity. As the heating amplitude is increased, a higher acceleration and faster swimming are achieved through synchronized beating of the cilia, which begin by producing oscillating swimming velocities and later give way to the usual gait. Finally, escape from a life-threatening aggression is achieved by a "jumping" gait, which does not rely on the cilia but is achieved through the explosive release of a group of trichocysts in the direction of the hot spot. Measurements through high-speed video explain the role of trichocysts in defending against aggressions while showing unexpected transitions in the swimming of microorganisms. These measurements also demonstrate that Paramecium optimizes its escape pattern by taking advantage of its inertia.

Mucormycosis (Mucor fungus ball) of the maxillary sinus.

Science.gov (United States)

Cho, Hang Sun; Yang, Hoon Shik; Kim, Kyung Soo

2014-01-01

A fungus ball is an extramucosal fungal proliferation that completely fills one or more paranasal sinuses and usually occurs as a unilateral infection. It is mainly caused by Aspergillus spp in an immunocompetent host, but some cases of paranasal fungal balls reportedly have been caused by Mucor spp. A Mucor fungus ball is usually found in the maxillary sinus and/or the sphenoid sinus and may be black in color. Patients with mucormycosis, or a Mucor fungal ball infection, usually present with facial pain or headache. On computed tomography, there are no pathognomonic findings that are conclusive for a diagnosis of mucormycosis. In this article we report a case of mucormycosis in a 56-year-old woman and provide a comprehensive review of the literature on the "Mucor fungus ball." To the best of our knowledge, 5 case reports (8 patients) have been published in which the fungus ball was thought to be caused by Mucor spp.

MAPCERN links to Google Street View

CERN Multimedia

Matilda Heron

2015-01-01

CERN’s online maps, MAPCERN, now have the added bonus of Google Street View, thanks to the new release of images of many CERN sites captured by Google.   New Street View images of CERN sites have been added to MAPCERN, see bottom-right-hand image in the screenshot above.   Google Street View, an integrated service of Google Maps introduced in 2007, links 360-degree panoramic photos into a virtual tour. CERN and Google began collaborating on this Street View project in 2010 and now these Street View images have been embedded into MAPCERN, accessible by clicking the “Street View” tab in MAPCERN’s bottom-right-hand window. If you need to locate a building at CERN, or plan an operation on some equipment, you can save time by using the Street View images to check out the area in advance. The CERN Meyrin site has been fully mapped, as well as the surfaces of the eight LHC points, BA2 and BA3. New Street View images of CERN, including the Pr...

SWIMMING CLASSES IN JUNIOR HIGH SCHOOL STUDENTS’ OPINION

Directory of Open Access Journals (Sweden)

Grzegorz Bielec

2013-02-01

Full Text Available The role of modern physical education is not only to develop motor abilities of the students, but most of all prevent them from epidemic youth diseases such as obesity or postural defects. Positive attitudes to swimming as a long-life physical activity, instilled in adolescence should be beneficial in adult life. The group of 130 boys and 116 girls of 7th grade junior high school (mean age 14.6 was asked in the survey to present their opinion of obligatory swimming lessons at school. Students of both sexes claimed that they liked swimming classes because they could improve their swimming skills (59% of answers and because of health-related character of water exercises (38%. 33% of students regarded swimming lessons as boring and monotonous, and 25% of them complained about poor pool conditions like chlorine smell, crowded lanes, too low temperature. Majority of the surveyed students saw practical role of swimming in saving others life.

Aerodynamics in the classroom and at the ball park

Science.gov (United States)

Cross, Rod

2012-04-01

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

Effect of soccer shoe upper on ball behaviour in curve kicks

Science.gov (United States)

Ishii, Hideyuki; Sakurai, Yoshihisa; Maruyama, Takeo

2014-08-01

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

How does gravity save or kill Q-balls?

OpenAIRE

Tamaki, Takashi; Sakai, Nobuyuki

2011-01-01

We explore stability of gravitating Q-balls with potential $V_4(\\phi)={m^2\\over2}\\phi^2-\\lambda\\phi^4+\\frac{\\phi^6}{M^2}$ via catastrophe theory, as an extension of our previous work on Q-balls with potential $V_3(\\phi)={m^2\\over2}\\phi^2-\\mu\\phi^3+\\lambda\\phi^4$. In flat spacetime Q-balls with $V_4$ in the thick-wall limit are unstable and there is a minimum charge $Q_{{\\rm min}}$, where Q-balls with $Q

Friction torque in thrust ball bearings grease lubricated

Science.gov (United States)

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

2016-08-01

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

Water Evaporation in Swimming Baths

DEFF Research Database (Denmark)

Hyldgård, Carl-Erik

This paper is publishing measuring results from models and full-scale baths of the evaporation in swimming baths, both public baths and retraining baths. Moreover, the heat balance of the basin water is measured. In addition the full-scale measurements have given many experiences which are repres......This paper is publishing measuring results from models and full-scale baths of the evaporation in swimming baths, both public baths and retraining baths. Moreover, the heat balance of the basin water is measured. In addition the full-scale measurements have given many experiences which...... are represented in instructions for carrying out and running swimming baths. If you follow the instructions you can achieve less investments, less heat consumption and a better comfort to the bathers....

Muscle dynamics in fish during steady swimming

DEFF Research Database (Denmark)

Shadwick, RE; Steffensen, JF; Katz, SL

1998-01-01

SYNOPSIS. Recent research in fish locomotion has been dominated by an interest in the dynamic mechanical properties of the swimming musculature. Prior observations have indicated that waves of muscle activation travel along the body of an undulating fish faster than the resulting waves of muscular...... position in swimming fish. Quantification of muscle contractile properties in cyclic contractions relies on in vitro experiments using strain and activation data collected in vivo. In this paper we discuss the relation between these parameters and body kinematics. Using videoradiographic data from swimming...... constant cross-section of red muscle along much of the body suggests that positive power for swimming is generated fairly uniformly along the length of the fish....

CREATINE SUPPLEMENTATION AND SWIM PERFORMANCE: A BRIEF REVIEW

Directory of Open Access Journals (Sweden)

Melissa J. Hopwood

2006-03-01

Full Text Available Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle

Laser Sintering Technology and Balling Phenomenon.

Science.gov (United States)

Oyar, Perihan

2018-02-01

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

Allegheny County Street Centerlines

Data.gov (United States)

Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains the locations of the street centerlines for vehicular and foot traffic in Allegheny County. Street Centerlines are classified as Primary Road,...

Health impact of disinfection by-products in swimming pools

Directory of Open Access Journals (Sweden)

Cristina M. Villanueva

2012-12-01

Full Text Available This article is focused on the epidemiological evidence on the health impacts related to disinfection by-products (DBPs in swimming pools, which is a chemical hazard generated as an undesired consequence to reduce the microbial pathogens. Specific DBPs are carcinogenic, fetotoxic and/or irritant to the airways according to experimental studies. Epidemiological evidence shows that swimming in pools during pregnancy is not associated with an increased risk of reproductive outcomes. An epidemiological study suggested an increased risk of bladder cancer with swimming pool attendance, although evidence is inconclusive. A higher prevalence of respiratory symptoms including asthma is found among swimming pool workers and elite swimmers, although the causality of this association is unclear. The body of evidence in children indicates that asthma is not increased by swimming pool attendance. Overall, the available knowledge suggests that the health benefits of swimming outweigh the potential health risks of chemical contamination. However, the positive effects of swimming should be enhanced by minimising potential risks.

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

Directory of Open Access Journals (Sweden)

Jacek NOWICKI

2008-05-01

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

Conceptual design of ball-screw type control element drive mechanism

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji Ho; Kim, Jong In; Huh, Hyung [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-10-01

In this report, the design features of ball-screw type CEDM with fine-step movement capability are described. The contents of this report are as follows: -Review of Design Requirements for Ball-screw type CEDM -System Description for Ball-screw type CEDM -Design of Ball Bearing and Ball-screw Assembly -Detail Design of Rotary Step Motor -Detail Design of Angular Position Indicator -Materials. The Ball-screw type CEDM described in this report is to be utilized as the starting point for design development of CEDM for SMART. 11 refs., 43 figs., 3 tabs. (Author)

Two Balls' Collision of Mass Ratio 3:1

Science.gov (United States)

Ogawara, Yasuo; Hull, Michael M.

2018-04-01

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

Swimming dynamics of bidirectional artificial flagella

NARCIS (Netherlands)

Namdeo, S.; Khaderi, S. N.; Onck, P. R.

2013-01-01

We study magnetic artificial flagella whose swimming speed and direction can be controlled using light and magnetic field as external triggers. The dependence of the swimming velocity on the system parameters (e. g., length, stiffness, fluid viscosity, and magnetic field) is explored using a

Swimming and muscle structure in fish

NARCIS (Netherlands)

Spierts, I.L.Y.

1999-01-01

In this series of studies the relations between swimming behaviour of fish in general and extreme swimming responses in particular (called fast starts or escape responses) and the structure and ontogeny of the muscle system was investigated. Special attention was paid to relate functional

The hydrodynamics of swimming microorganisms

International Nuclear Information System (INIS)

Lauga, Eric; Powers, Thomas R

2009-01-01

Cell motility in viscous fluids is ubiquitous and affects many biological processes, including reproduction, infection and the marine life ecosystem. Here we review the biophysical and mechanical principles of locomotion at the small scales relevant to cell swimming, tens of micrometers and below. At this scale, inertia is unimportant and the Reynolds number is small. Our emphasis is on the simple physical picture and fundamental flow physics phenomena in this regime. We first give a brief overview of the mechanisms for swimming motility, and of the basic properties of flows at low Reynolds number, paying special attention to aspects most relevant for swimming such as resistance matrices for solid bodies, flow singularities and kinematic requirements for net translation. Then we review classical theoretical work on cell motility, in particular early calculations of swimming kinematics with prescribed stroke and the application of resistive force theory and slender-body theory to flagellar locomotion. After examining the physical means by which flagella are actuated, we outline areas of active research, including hydrodynamic interactions, biological locomotion in complex fluids, the design of small-scale artificial swimmers and the optimization of locomotion strategies.

Street Politics

Directory of Open Access Journals (Sweden)

Michael J. Shapiro

2012-03-01

Full Text Available I write from Prague, where, unlike in most urban formations, the main city street plays an iconic role; it references a history of political protest. However, before elaborating on the protest iconography of the Prague street, Vaclavske nam, I want to locate the ways in which the design of urban space is actualized in everyday life in the cities of the world. Three functions stand out; the first involves dwelling, the second seeing, and the third moving. With respect to the first function – dwelling – the design partitions and coordinates residential, commercial and leisure functions. At times these are organized to segregate different classes (Robert Moses’ redesign of much of New York stands out with respect to the segregation function. With respect to the second function – seeing – the design of urban space is allegiance-inspiring; it involves sight lines that afford urban dwellers and visitors views of iconic buildings and statues, which reference key founding moments in the past and/or authoritative political functions in the present (Here, L’Enfants design for Washington DC stands out as exemplary. Its manifest intention was to make the buildings housing executive, legislative and judicial functions visible from many vantage points. Rarely are the streets themselves iconic. Their dominant role is involved with the effectuation of movement. As for this third function: As Lewis Mumford famously points out, streets were once part of an asterisk design, radiating out from an exemplary, often spiritual center...

Hydrodynamic attraction of swimming microorganisms by surfaces

OpenAIRE

Berke, Allison P.; Turner, Linda; Berg, Howard C.; Lauga, Eric

2008-01-01

Cells swimming in confined environments are attracted by surfaces. We measure the steady-state distribution of smooth-swimming bacteria (Escherichia coli) between two glass plates. In agreement with earlier studies, we find a strong increase of the cell concentration at the boundaries. We demonstrate theoretically that hydrodynamic interactions of the swimming cells with solid surfaces lead to their re-orientation in the direction parallel to the surfaces, as well as their attraction by the c...

Biomechanics of Heading a Soccer Ball: Implications for Player Safety

Directory of Open Access Journals (Sweden)

Charles F. Babbs

2001-01-01

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

Zebrafish swimming in the flow: a particle image velocimetry study

Directory of Open Access Journals (Sweden)

Violet Mwaffo

2017-11-01

Full Text Available Zebrafish is emerging as a species of choice for the study of a number of biomechanics problems, including balance development, schooling, and neuromuscular transmission. The precise quantification of the flow physics around swimming zebrafish is critical toward a mechanistic understanding of the complex swimming style of this fresh-water species. Although previous studies have elucidated the vortical structures in the wake of zebrafish swimming in placid water, the flow physics of zebrafish swimming against a water current remains unexplored. In an effort to illuminate zebrafish swimming in a dynamic environment reminiscent of its natural habitat, we experimentally investigated the locomotion and hydrodynamics of a single zebrafish swimming in a miniature water tunnel using particle image velocimetry. Our results on zebrafish locomotion detail the role of flow speed on tail beat undulations, heading direction, and swimming speed. Our findings on zebrafish hydrodynamics offer a precise quantification of vortex shedding during zebrafish swimming and demonstrate that locomotory patterns play a central role on the flow physics. This knowledge may help clarify the evolutionary advantage of burst and cruise swimming movements in zebrafish.

Quiet swimming at low Reynolds number

DEFF Research Database (Denmark)

Andersen, Anders Peter; Wadhwa, Navish; Kiørboe, Thomas

2015-01-01

The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that elim......The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode...... that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three......-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws...

Road and Street Centerlines, Street-The data set is a line feature consisting of 13948 line segments representing streets. It was created to maintain the location of city and county based streets., Published in 1989, Davis County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Road and Street Centerlines dataset current as of 1989. Street-The data set is a line feature consisting of 13948 line segments representing streets. It was created...

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...... limited and temporally ephemeral owing to jump-impulsiveness and viscous decay. In contrast, continuous steady swimming generates two well-extended long-lasting momentum jets both in front of and behind the swimmer, as suggested by the well-known steady stresslet model. Based on the observed jump-swimming...... kinematics of a small copepod Oithona davisae, we further showed that jump-swimming produces a hydrodynamic disturbance with much smaller spatial extension and shorter temporal duration than that produced by a same-size copepod cruising steadily at the same average translating velocity. Hence, small copepods...

Mean Streets: An analysis on street level pollution in NYC

Science.gov (United States)

Parker, G.

2017-12-01

The overarching objective of this study is to quantify the spatial and temporal variability in particulatematter concentration (PM 2.5) along crowded streets in New York City. Due to their fine size and lowdensity PM 2.5 stays longer in the atmosphere and could bypass human nose and throat and penetratedeep in to the lungs and even enter the circulatory system. PM 2.5 is a by-product of automobilecombustion and is a primary cause of respiratory malfunction in NYC. The study would monitor streetlevel concentration of PM2.5 across three different routes that witness significant pedestrian traffic;observations will be conducted along these three routes at different time periods. The study will use theAirBeam community air quality monitor. The monitor tracks PM 2.5 concentration along with GPS, airtemperature and relative humidity. The surface level concentration monitored by AirBeam will becompared with atmospheric concentration of PM 2.5 that are monitored at the NOAA CREST facility onCCNY campus. The lower atmospheric values will be correlated with street level values to assess thevalidity of using of lower atmospheric values to predict street level concentrations. The street levelconcentration will be compared to the air quality forecasted by the New York Department ofEnvironment Conservation to estimate its accuracy and applicability.

Street art - vandalismus nebo umění?

OpenAIRE

Grabmüllerová, Eva

2012-01-01

The diploma thesis ‚Street Art - Vandalism or Art?' deals with a world-wide phenomenon of contemporary art. The thesis focuses on the characterization of street art and history of street art (its origin and development) and analyzes the difference between street art and graffiti. The thesis presents street art techniques as well as notable street artists. The thesis also observes street art scene in the Czech Republic and depicts features that street art has in common with other art movements...

Swimming of Paramecium in confined channels

Science.gov (United States)

Jung, Sunghwan

2012-02-01

Many living organisms in nature have developed a few different swimming modes, presumably derived from hydrodynamic advantage. Paramecium is a ciliated protozoan covered by thousands of cilia with a few nanometers in diameter and tens of micro-meters in length and is able to exhibit both ballistic and meandering motions. First, we characterize ballistic swimming behaviors of ciliated microorganisms in glass capillaries of different diameters and explain the trajectories they trace out. We develop a theoretical model of an undulating sheet with a pressure gradient and discuss how it affects the swimming speed. Secondly, investigation into meandering swimmings within rectangular PDMS channels of dimension smaller than Paramecium length. We find that Paramecium executes a body-bend (an elastic buckling) using the cilia while it meanders. By considering an elastic beam model, we estimate and show the universal profile of forces it exerts on the walls. Finally, we discuss a few other locomotion of Paramecium in other extreme environments like gel.

Swimming Performance of Toy Robotic Fish

Science.gov (United States)

Petelina, Nina; Mendelson, Leah; Techet, Alexandra

2015-11-01

HEXBUG AquaBotsTM are a commercially available small robot fish that come in a variety of ``species''. These models have varying caudal fin shapes and randomly-varied modes of swimming including forward locomotion, diving, and turning. In this study, we assess the repeatability and performance of the HEXBUG swimming behaviors and discuss the use of these toys to develop experimental techniques and analysis methods to study live fish swimming. In order to determine whether these simple, affordable model fish can be a valid representation for live fish movement, two models, an angelfish and a shark, were studied using 2D Particle Image Velocimetry (PIV) and 3D Synthetic Aperture PIV. In a series of experiments, the robotic fish were either allowed to swim freely or towed in one direction at a constant speed. The resultant measurements of the caudal fin wake are compared to data from previous studies of a real fish and simplified flapping propulsors.

The Fluid Dynamics of Competitive Swimming

Science.gov (United States)

Wei, Timothy; Mark, Russell; Hutchison, Sean

2014-01-01

Nowhere in sport is performance so dependent on the interaction of the athlete with the surrounding medium than in competitive swimming. As a result, understanding (at least implicitly) and controlling (explicitly) the fluid dynamics of swimming are essential to earning a spot on the medal stand. This is an extremely complex, highly multidisciplinary problem with a broad spectrum of research approaches. This review attempts to provide a historical framework for the fluid dynamics-related aspects of human swimming research, principally conducted roughly over the past five decades, with an emphasis on the past 25 years. The literature is organized below to show a continuous integration of computational and experimental technologies into the sport. Illustrations from the authors' collaborations over a 10-year period, coupling the knowledge and experience of an elite-level coach, a lead biomechanician at USA Swimming, and an experimental fluid dynamicist, are intended to bring relevance and immediacy to the review.

On longevity of I-ball/oscillon

Energy Technology Data Exchange (ETDEWEB)

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

2017-03-23

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

The role of students’ self-confidence in relation with swimming routines, frequency, and tutor in swimming class

Science.gov (United States)

Hartoto, S.; Khory, F. D.; Prakoso, B. B.

2018-01-01

It is compulsory for prospective physical education teachers to have the ability to perform swimming. The average of students’ passing in swimming class has reached 72%. Most students who failed to pass the class are those who have had aquaphobia, the condition in which one failed to perceive a situation in a positive and objective, some of which are hard to detect. This perception may come from past experience and it could diminish students’ confidence. Furthermore, the lack of confidence in students may cause unsatisfactory learning results. Therefore it is critical for the teachers to have a comprehensive knowledge of their students’ past experience in formulating a lesson. This research used descriptive qualitative approach. The aim of this article is to investigate the correlation between students’ confidence level and swimming routines, frequency, and tutors in order to succeed swimming class. This article will attempt to describe the results of a research conducted to 139 students of Department of Sport Education Universitas Negeri Surabaya as prospective physical education teachers in Indonesia who took swimming class. Past experience and confidence level are measured by a questionnaire. The results of the research show that students who have a higher level of confidence are those who follow practice routines with adequate frequency and helped by a compatible tutor.

Personal and Familial Properties of Street Children--"Street Children: The Forgotten or Not Remembered Ones"

Science.gov (United States)

Özbas, Mehmet

2015-01-01

With this research it is aimed to determine the personal traits of Street Children depending on them and also the socio-economic variables of Street Children resulting from their families. For this main aim in the research process, it is provided to have communication directly with the parents of Street Children using one-to-one and face-to-face…

Comparison of physical fitness tests in swimming

OpenAIRE

Dostálová, Sabina

2015-01-01

Title: Comparison of physical fitness tests in swimming. Objective: The aim of this thesis is to evaluate specific tests, used while testing selected physical abilities in swimming. By specific tests we mean tests realized in the water. Selected tests are intended for swim coaches, who train junior to senior age groups. Methods: The chosen method was a comparison of studies, that pursue selected specific tests. We created partial conclusions for every test by summing up the results of differe...

A general theory for ball lightning structure and light output

Science.gov (United States)

Morrow, R.

2018-03-01

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

Estimating Wear Of Installed Ball Bearings

Science.gov (United States)

Keba, John E.; Mcvey, Scott E.

1993-01-01

Simple inspection and measurement technique makes possible to estimate wear of balls in ball bearing, without removing bearing from shaft on which installed. To perform measurement, one observes bearing cage while turning shaft by hand to obtain integral number of cage rotations and to measure, to nearest 2 degrees, number of shaft rotations producing cage rotations. Ratio between numbers of cages and shaft rotations depends only on internal geometry of bearing and applied load. Changes in turns ratio reflect changes in internal geometry of bearing provided measurements made with similar bearing loads. By assuming all wear occurs on balls, one computes effective value for this wear from change in turns ratio.

The social world of street children : street children's peer friendship, group life and subculture in Addis Ababa, Ethiopia

OpenAIRE

Fikre, Kaleab

2016-01-01

This study attempts to explore the street children’s social world, focusing on their peer friendship, group life, and street subculture in Addis Ababa, Ethiopia. The study shows how street children’s peer friendship, street group, and subculture are part and parcel of children’s quest for survival in the street in the absence of guardians conventionally considered as responsible for the provision and protection of children. The main perspective of the study is grounded in the p...

Ball-and-socket ankle joint

International Nuclear Information System (INIS)

Pistoia, F.; Ozonoff, M.B.; Wintz, P.; Hartford Hospital, CT

1987-01-01

The ball-and-socket ankle joint is a malformation of the ankle in which the articular surface of the talus is hemispherical in both the anteroposterior and lateral projections and has a congruent, concave tibial articular surface. Fourteen patients with this condition were identified retrospectively. Thirteen patients were thought to have the congenital type of ball-and-socket ankle joint which in many was associated with tarsal coalition, short limb, and ray fusion and deletion anomalies. One case of the acquired type, demonstrating less geometric rounding of the talar margins, was seen in a patient with myelomeningocele, probably resulting from sensory and motor deficits. Although the exact etiology of the congenital type is unknown, its association with other malformations suggests that the ball-and-socket ankle joint results from an overall maldevelopment of the ankle and foot. (orig.)

COMMON GROUNDS BETWEEN PRINTMAKING AND STREET ART

Directory of Open Access Journals (Sweden)

Burcak Balamber

2016-09-01

Full Text Available Graffiti movement, born as a result of an effort of the youth, who felt themselves socially excluded and alone, to show their existence and identities during the 1960s, expanded its scope owing to street based artists such as Keith Haring and Jean-Michel Basquiat entering to the galleries, and transformed into an artistic manner of expression having aesthetic concerns by adopting a more inclusive definition ‘street art’. During this transformation of street art,street artists experimented with various methods from many different disciplines and hence created works in a wide range of varieties in terms of plastic and artistic values. Among these disciplines, printmakinghastaken its own place in street artas a discipline thatdeeply influenced street artists.Printmaking has fascinated street artists and become a part of their production process, not only with its philosophy sharing common grounds with street art and advantages in terms of its tecnical practices but also its unique plastic and linear values.Thanks to the opportunities of printmaking, street art has succeeded creating a tremendous impression worldwide, and even positioned itself into today’s greatest museums/gallery halls. This article aims to show how and in what way printmaking has influenced street art being in a transformation since the 1960s, and to put an emphasis on theimportance of printmaking on today’s street art.

Intelligent street lighting clustering

NARCIS (Netherlands)

Verhoeven, R.; Jovanovic, N.; Lukkien, J.J.

2014-01-01

The advances in dynamic street lighting introduce new functionality for control and maintenance of the street lighting infrastructure. Vital elements in this infrastructure are the powerful controlling devices that control separate groups of light poles and collect information from the system. For

Laryngoscopy during swimming: A novel diagnostic technique to characterize swimming-induced laryngeal obstruction.

Science.gov (United States)

Walsted, Emil S; Swanton, Laura L; van van Someren, Ken; Morris, Tessa E; Furber, Matthew; Backer, Vibeke; Hull, James H

2017-10-01

Exercise-induced laryngeal obstruction (EILO) is a key differential diagnosis for respiratory symptoms in athletes and is particularly prevalent in aquatic athletes. A definitive diagnosis of EILO is dependent on laryngoscopy, performed continuously, while an athlete engages in the sport that precipitates their symptoms. This report provides the first description of the feasibility of performing continuous laryngoscopy during exercise in a swimming environment. The report describes the methodology and safety of the use of continuous laryngoscopy while swimming. Laryngoscope, 127:2298-2301, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

The Effect of Concurrent Visual Feedback on Controlling Swimming Speed

Directory of Open Access Journals (Sweden)

Szczepan Stefan

2016-03-01

Full Text Available Introduction. Developing the ability to control the speed of swimming is an important part of swimming training. Maintaining a defined constant speed makes it possible for the athlete to swim economically at a low physiological cost. The aim of this study was to determine the effect of concurrent visual feedback transmitted by the Leader device on the control of swimming speed in a single exercise test. Material and methods. The study involved a group of expert swimmers (n = 20. Prior to the experiment, the race time for the 100 m distance was determined for each of the participants. In the experiment, the participants swam the distance of 100 m without feedback and with visual feedback. In both variants, the task of the participants was to swim the test distance in a time as close as possible to the time designated prior to the experiment. In the first version of the experiment (without feedback, the participants swam the test distance without receiving real-time feedback on their swimming speed. In the second version (with visual feedback, the participants followed a beam of light moving across the bottom of the swimming pool, generated by the Leader device. Results. During swimming with visual feedback, the 100 m race time was significantly closer to the time designated. The difference between the pre-determined time and the time obtained was significantly statistically lower during swimming with visual feedback (p = 0.00002. Conclusions. Concurrently transmitting visual feedback to athletes improves their control of swimming speed. The Leader device has proven useful in controlling swimming speed.

Swimming in air-breathing fishes.

Science.gov (United States)

Lefevre, S; Domenici, P; McKenzie, D J

2014-03-01

Fishes with bimodal respiration differ in the extent of their reliance on air breathing to support aerobic metabolism, which is reflected in their lifestyles and ecologies. Many freshwater species undertake seasonal and reproductive migrations that presumably involve sustained aerobic exercise. In the six species studied to date, aerobic exercise in swim flumes stimulated air-breathing behaviour, and there is evidence that surfacing frequency and oxygen uptake from air show an exponential increase with increasing swimming speed. In some species, this was associated with an increase in the proportion of aerobic metabolism met by aerial respiration, while in others the proportion remained relatively constant. The ecological significance of anaerobic swimming activities, such as sprinting and fast-start manoeuvres during predator-prey interactions, has been little studied in air-breathing fishes. Some species practise air breathing during recovery itself, while others prefer to increase aquatic respiration, possibly to promote branchial ion exchange to restore acid-base balance, and to remain quiescent and avoid being visible to predators. Overall, the diversity of air-breathing fishes is reflected in their swimming physiology as well, and further research is needed to increase the understanding of the differences and the mechanisms through which air breathing is controlled and used during exercise. © 2014 The Fisheries Society of the British Isles.

Swimming-pool piles; Piles piscines

Energy Technology Data Exchange (ETDEWEB)

Trioulaire, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

In France two swimming-pool piles, Melusine and Triton, have just been set in operation. The swimming-pool pile is the ideal research tool for neutron fluxes of the order of 10{sup 13}. This type of pile can be of immediate interest to many research centres, but its cost must be reduced and a break with tradition should be observed in its design. It would be an advantage: - to bury the swimming-pool; - to reject the experimental channel; - to concentrate the cooling circuit in the swimming-pool; - to carry out all manipulations in the water; - to double the core. (author) [French] En France, deux piles piscines, Melusine et Triton, viennent d'entrer en service. La pile piscine est l'outil de recherche ideal pour des flux de neutrons de l'ordre de 10{sup 13}. Ce type de pile peut interesser des maintenant de nombreux centres de recherches mais il faut reduire son prix de revient et rompre avec le conformisme de sa conception. Il y a avantage: - a enterrer la piscine; - a supprimer les canaux experimentaux; - a concentrer le circuit de refrigeration dans la piscine; - a effectuer toutes les manipulations dans l'eau; - a doubler le coeur. (auteur)

Upward swimming of a sperm cell in shear flow.

Science.gov (United States)

Omori, Toshihiro; Ishikawa, Takuji

2016-03-01

Mammalian sperm cells are required to swim over long distances, typically around 1000-fold their own length. They must orient themselves and maintain a swimming motion to reach the ovum, or egg cell. Although the mechanism of long-distance navigation is still unclear, one possible mechanism, rheotaxis, was reported recently. This work investigates the mechanism of the rheotaxis in detail by simulating the motions of a sperm cell in shear flow adjacent to a flat surface. A phase diagram was developed to show the sperm's swimming motion under different shear rates, and for varying flagellum waveform conditions. The results showed that, under shear flow, the sperm is able to hydrodynamically change its swimming direction, allowing it to swim upwards against the flow, which suggests that the upward swimming of sperm cells can be explained using fluid mechanics, and this can then be used to further understand physiology of sperm cell navigation.

Paramecium swimming in capillary tube

Science.gov (United States)

Jana, Saikat; Um, Soong Ho; Jung, Sunghwan

2012-04-01

Swimming organisms in their natural habitat need to navigate through a wide range of geometries and chemical environments. Interaction with boundaries in such situations is ubiquitous and can significantly modify the swimming characteristics of the organism when compared to ideal laboratory conditions. We study the different patterns of ciliary locomotion in glass capillaries of varying diameter and characterize the effect of the solid boundaries on the velocities of the organism. Experimental observations show that Paramecium executes helical trajectories that slowly transition to straight lines as the diameter of the capillary tubes decreases. We predict the swimming velocity in capillaries by modeling the system as a confined cylinder propagating longitudinal metachronal waves that create a finite pressure gradient. Comparing with experiments, we find that such pressure gradient considerations are necessary for modeling finite sized ciliary organisms in restrictive geometries.

Optimal swimming of a sheet.

Science.gov (United States)

Montenegro-Johnson, Thomas D; Lauga, Eric

2014-06-01

Propulsion at microscopic scales is often achieved through propagating traveling waves along hairlike organelles called flagella. Taylor's two-dimensional swimming sheet model is frequently used to provide insight into problems of flagellar propulsion. We derive numerically the large-amplitude wave form of the two-dimensional swimming sheet that yields optimum hydrodynamic efficiency: the ratio of the squared swimming speed to the rate-of-working of the sheet against the fluid. Using the boundary element method, we show that the optimal wave form is a front-back symmetric regularized cusp that is 25% more efficient than the optimal sine wave. This optimal two-dimensional shape is smooth, qualitatively different from the kinked form of Lighthill's optimal three-dimensional flagellum, not predicted by small-amplitude theory, and different from the smooth circular-arc-like shape of active elastic filaments.

StreetMekka - Ledelse af Københavns nye streetkulturhus

OpenAIRE

Gjelstrup, Mikkel

2009-01-01

Street culture is spreading out through the streets of Denmark and in the summer of 2009 the City of Copenhagen will open up an indoor street culture facility called StreetMekka. Moving street culture from its natural concrete habitat to a communal facility presents challenges. The City of Copenhagen has made official guideline for the StreetMekka facility to follow, but the free and self organized street culture is not an easy thing to keep within guidelines. This master thesis discusses fro...

Unsteady bio-fluid dynamics in flying and swimming

Science.gov (United States)

Liu, Hao; Kolomenskiy, Dmitry; Nakata, Toshiyuki; Li, Gen

2017-08-01

Flying and swimming in nature present sophisticated and exciting ventures in biomimetics, which seeks sustainable solutions and solves practical problems by emulating nature's time-tested patterns, functions, and strategies. Bio-fluids in insect and bird flight, as well as in fish swimming are highly dynamic and unsteady; however, they have been studied mostly with a focus on the phenomena associated with a body or wings moving in a steady flow. Characterized by unsteady wing flapping and body undulation, fluid-structure interactions, flexible wings and bodies, turbulent environments, and complex maneuver, bio-fluid dynamics normally have challenges associated with low Reynolds number regime and high unsteadiness in modeling and analysis of flow physics. In this article, we review and highlight recent advances in unsteady bio-fluid dynamics in terms of leading-edge vortices, passive mechanisms in flexible wings and hinges, flapping flight in unsteady environments, and micro-structured aerodynamics in flapping flight, as well as undulatory swimming, flapping-fin hydrodynamics, body-fin interaction, C-start and maneuvering, swimming in turbulence, collective swimming, and micro-structured hydrodynamics in swimming. We further give a perspective outlook on future challenges and tasks of several key issues of the field.

Grundfoss: Chlorination of Swimming Pools

DEFF Research Database (Denmark)

Hjorth, Poul G.; Hogan, John; Andreassen, Viggo

1998-01-01

Grundfos asked for a model, describing the problem of mixing chemicals, being dosed into water systems, to be developed. The application of the model should be dedicated to dosing aqueous solution of chlorine into swimming pools.......Grundfos asked for a model, describing the problem of mixing chemicals, being dosed into water systems, to be developed. The application of the model should be dedicated to dosing aqueous solution of chlorine into swimming pools....

A forced damped oscillation framework for undulatory swimming provides new insights into how propulsion arises in active and passive swimming.

Science.gov (United States)

Bhalla, Amneet Pal Singh; Griffith, Boyce E; Patankar, Neelesh A

2013-01-01

A fundamental issue in locomotion is to understand how muscle forcing produces apparently complex deformation kinematics leading to movement of animals like undulatory swimmers. The question of whether complicated muscle forcing is required to create the observed deformation kinematics is central to the understanding of how animals control movement. In this work, a forced damped oscillation framework is applied to a chain-link model for undulatory swimming to understand how forcing leads to deformation and movement. A unified understanding of swimming, caused by muscle contractions ("active" swimming) or by forces imparted by the surrounding fluid ("passive" swimming), is obtained. We show that the forcing triggers the first few deformation modes of the body, which in turn cause the translational motion. We show that relatively simple forcing patterns can trigger seemingly complex deformation kinematics that lead to movement. For given muscle activation, the forcing frequency relative to the natural frequency of the damped oscillator is important for the emergent deformation characteristics of the body. The proposed approach also leads to a qualitative understanding of optimal deformation kinematics for fast swimming. These results, based on a chain-link model of swimming, are confirmed by fully resolved computational fluid dynamics (CFD) simulations. Prior results from the literature on the optimal value of stiffness for maximum speed are explained.

Scaling the Thrust Production and Energetics of Inviscid Intermittent Swimming

Science.gov (United States)

Akoz, Emre; Moored, Keith

2015-11-01

Many fish have adopted an intermittent swimming gait sometimes referred as a burst-and-coast behavior. By using this gait, fish have been estimated at reducing their energetic cost of swimming by about 50%. Lighthill proposed that the skin friction drag of an undulating body can be around 400% greater than a rigidly-held coasting body, which may explain the energetic savings of intermittent swimming. Recent studies have confirmed the increase in skin friction drag over an undulating body, however, the increase is on the order of 20-70%. This more modest gain in skin friction drag is not sufficient to lead to the observed energy savings. Motivated by these observations, we investigate the inviscid mechanisms behind intermittent swimming for parameters typical of biology. We see that there is an energy savings at a fixed swimming speed for intermittent swimming as compared to continuous swimming. Then we consider three questions: What is the nature of the inviscid mechanism that leads to the observed energy savings, how do the forces and energetics of intermittent swimming scale with the swimming parameters, and what are the limitations to the benefit? Supported by the Office of Naval Research under Program Director Dr. Bob Brizzola, MURI grant number N00014-14-1-0533.

Flow disturbances generated by feeding and swimming zooplankton

DEFF Research Database (Denmark)

Kiørboe, Thomas; Jiang, Haisong; Goncalves, R. J.

2014-01-01

that zooplankton, in which feeding and swimming are separate processes, produce flow disturbances during swimming with a much faster spatial attenuation (velocity u varies with distance r as u ∝ r−3 to r−4) than that produced by zooplankton for which feeding and propulsion are the same process (u ∝ r−1 to r−2...... vortex rings, or by “breast-stroke swimming.” Both produce rapidly attenuating flows. The more “noisy” swimming of those that are constrained by a need to simultaneously feed is due to constantly beating flagella or appendages that are positioned either anteriorly or posteriorly on the (cell) body...

Are parents just treading water? The impact of participation in swim lessons on parents' judgments of children's drowning risk, swimming ability, and supervision needs.

Science.gov (United States)

Morrongiello, Barbara A; Sandomierski, Megan; Schwebel, David C; Hagel, Brent

2013-01-01

Drowning is a leading cause of child mortality globally. Strategies that have been suggested to reduce pediatric drowning risk include increased parental awareness of children's swimming ability and drowning risk, improved adult supervision of child swimmers, and providing swim lessons to children. This study explored how parents' beliefs relevant to children's drowning risk, perception of children's swimming ability, and judgments of supervision needs changed as children aged two through 5 years accumulated experience in swim lessons, and compared a parent group who received regular, detailed feedback about their child's swim skills with one that did not. Parents completed questionnaire measures near the beginning and end of a series of 10 weekly swim lessons. Results revealed that parental accuracy in judging children's swimming abilities remained relatively poor even though it improved from the beginning to the end of the swim lessons. Supervision needs were underestimated and did not vary with program or change over the course of swim lessons. Children's ability to keep themselves from drowning was overestimated and did not change over lessons or vary with program; parents believed that children could save themselves from drowning by the age of 6.21 years. Parents who had experienced a close call for drowning showed greater awareness of children's drowning risk and endorsed more watchful and proximal supervision. Results suggest that expanding learn-to-swim programs to include a parent-focused component that provides detailed tracking of swim skills and delivers messaging targeting perceptions of children's drowning risk and supervision needs may serve to maximize the drowning protection afforded by these programs. Delivering messaging in the form of 'close-call' drowning stories may prove especially effective to impact parents' supervision practices in drowning risk situations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reactive-inspired ball-milling synthesis of an ODS steel: study of the influence of ball-milling and annealing

International Nuclear Information System (INIS)

Brocq, M.

2010-10-01

In the context of the development of new ODS (Oxide Dispersion Strengthened) steels as core materials in future nuclear reactors, we investigated a new process inspired by reactive ball-milling which consists in using YFe 3 andFe 2 O 3 as starting reactants instead of Y 2 O 3 to produce a dispersion of nano-oxides in a steel matrix and the influence of synthesis conditions on the nano-oxide characteristics were studied. For that aim, ODS steels were prepared by ball-milling and then annealed. Multi-scale characterizations were performed after each synthesis step, using notably atom probe tomography and small angle neutron scattering. The process inspired by reactive ball-milling was shown to be efficient for ODS steel synthesis, but it does not modify the nano-oxide characteristics as compared to those of oxides directly incorporated in the matrix by ball-milling. Broadly speaking, the nature of the starting oxygen bearing reactants has no influence on nano-oxide formation. Moreover, we showed that the nucleation of nano-oxides nucleation can start during milling and continues during annealing with a very fast kinetic. The final characteristics of nano-oxides formed in this way can be monitored through ball-milling parameters (intensity, temperature and atmosphere) and annealing parameters (duration and temperature). (author)

Road and Street Centerlines, StreetLabels-The data set is a text feature consisting of 6329 label points representing street names. It was created to show the names of city and county based streets., Published in 1989, Davis County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Road and Street Centerlines dataset current as of 1989. StreetLabels-The data set is a text feature consisting of 6329 label points representing street names. It was...

Road and Street Centerlines - COUNTY_STREET_CENTERLINES_IDHS_IN: Street Centerlines Maintained by County Agencies in Indiana (Indiana Department of Homeland Security, Line Shapefile)

Data.gov (United States)

NSGIC State | GIS Inventory — COUNTY_STREET_CENTERLINES_IDHS_IN is a line feature class that contains street centerlines maintained by county agencies in Indiana, provided by personnel of Indiana...

CFD Analysis of Swing of Cricket Ball and Trajectory Prediction

Science.gov (United States)

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

2013-11-01

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

Multidisciplinary teaching in swimming: methodological reflection and proposal of check list

Directory of Open Access Journals (Sweden)

Sofia Canossa

2007-12-01

Full Text Available The present study proposes a new multidisciplinary approach related to teaching in swimming. Swimming is an interdisciplinary physical activity, which can be truly important at the level of the motor learning and experimentation in aquatic activities. In the present manuscript, it was compared the present reality of teaching in Swimming with a new perspective, this one with a multidisciplinary scope. Following the referred analysis, it was presented a discussion about the orientation and adequacy of the contents of the Swimming curriculum for children and youngsters, which are populations with specific characteristics and development necessities. In this sense, after stating the relevance of a multidisciplinary perspective, it was proposed a new approach for basic aquatic motor skills acquisition based on four disciplines: swimming, water polo, synchronised swimming and platform diving. This was made taking into account the initial stage of swimming teaching, i.e., aquatic readiness. This proposal aims mainly at implementing the teaching of Swimming at a multidisciplinary point of view that, in our opinion, is urgent, namely due to the small expression that the aquatic modalities traditionally considered as swimming satellites (water polo, synchronised swimming and platform diving have in the Portuguese sports context.

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

Directory of Open Access Journals (Sweden)

Charikova K.M.

2012-03-01

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

Do suburban residents want to pay for wide streets? a survey on consumer preference and ability to afford towards wide street and on-street parking in American suburbia.

Science.gov (United States)

2016-08-01

All local governments in the U.S. set the street minimum width and cross-section design for local : neighborhood streets. Because local streets typically require no more than two traffic lanes (approx. 20 feet : wide), a minimum width of 26 feet or w...

A Review of Swimming Cues and Tips for Physical Education

Science.gov (United States)

Higginson, Kelsey; Barney, David

2016-01-01

Swimming is a low-impact activity that causes little stress on joints so it can be done for a lifetime. Many teachers may wish to teach swimming but do not have cues or ideas for doing so. This article reviews swimming cues, relays and equipment that can help a physical education teacher include a swimming unit in their curriculum. Certification…

Ball lightning as a route to fusion energy

International Nuclear Information System (INIS)

Roth, J.R.

1989-01-01

The reality of ball lightning is attested to by observations reported in surveys of large populations, which are the subject of several books. These observations indicate that its characteristics may be relevant to fusion energy applications. Ball lightning can have a diameter up to several meters, a lifetime of over 100 seconds, an energy content in excess of 10 megajoules, and an energy density and a kinetic pressure greater than that of a reacting DT plasma. This paper reviews some of the properties of ball lightning which commend it to the attention of the fusion community, and it discusses some potential advantages and applications of ball lightning fusion reactors. 11 refs., 6 figs., 1 tab

Fish Swimming and Bird/Insect Flight

Science.gov (United States)

Wu, Theodore Yaotsu

2011-01-01

This expository review is devoted to fish swimming and bird/insect flight. (a) The simple waving motion of an elongated flexible ribbon plate of constant width propagating a wave distally down the plate to swim forward in a fluid, initially at rest, is first considered to provide a fundamental concept on energy conservation. It is generalized to include variations in body width and thickness, with appended dorsal, ventral and caudal fins shedding vortices to closely simulate fish swimming, for which a nonlinear theory is presented for large-amplitude propulsion. (b) For bird flight, the pioneering studies on oscillatory rigid wings are discussed with delineating a fully nonlinear unsteady theory for a two-dimensional flexible wing with arbitrary variations in shape and trajectory to provide a comparative study with experiments. (c) For insect flight, recent advances are reviewed by items on aerodynamic theory and modeling, computational methods, and experiments, for forward and hovering flights with producing leading-edge vortex to yield unsteady high lift. (d) Prospects are explored on extracting prevailing intrinsic flow energy by fish and bird to enhance thrust for propulsion. (e) The mechanical and biological principles are drawn together for unified studies on the energetics in deriving metabolic power for animal locomotion, leading to the surprising discovery that the hydrodynamic viscous drag on swimming fish is largely associated with laminar boundary layers, thus drawing valid and sound evidences for a resounding resolution to the long-standing fish-swim paradox proclaimed by Gray (1936, 1968 ).

On burst-and-coast swimming performance in fish-like locomotion

International Nuclear Information System (INIS)

Chung, M-H

2009-01-01

Burst-and-coast swimming performance in fish-like locomotion is studied via two-dimensional numerical simulation. The numerical method used is the collocated finite-volume adaptive Cartesian cut-cell method developed previously. The NACA00xx airfoil shape is used as an equilibrium fish-body form. Swimming in a burst-and-coast style is computed assuming that the burst phase is composed of a single tail-beat. Swimming efficiency is evaluated in terms of the mass-specific cost of transport instead of the Froude efficiency. The effects of the Reynolds number (based on the body length and burst time), duty cycle and fineness ratio (the body length over the largest thickness) on swimming performance (momentum capacity and the mass-specific cost of transport) are studied quantitatively. The results lead to a conclusion consistent with previous findings that a larval fish seldom swims in a burst-and-coast style. Given mass and swimming speed, a fish needs the least cost if it swims in a burst-and-coast style with a fineness ratio of 8.33. This energetically optimal fineness ratio is larger than that derived from the simple hydromechanical model proposed in literature. The calculated amount of energy saving in burst-and-coast swimming is comparable with the real-fish estimation in the literature. Finally, the predicted wake-vortex structures of both continuous and burst-and-coast swimming are biologically relevant.

On burst-and-coast swimming performance in fish-like locomotion.

Science.gov (United States)

Chung, M-H

2009-09-01

Burst-and-coast swimming performance in fish-like locomotion is studied via two-dimensional numerical simulation. The numerical method used is the collocated finite-volume adaptive Cartesian cut-cell method developed previously. The NACA00xx airfoil shape is used as an equilibrium fish-body form. Swimming in a burst-and-coast style is computed assuming that the burst phase is composed of a single tail-beat. Swimming efficiency is evaluated in terms of the mass-specific cost of transport instead of the Froude efficiency. The effects of the Reynolds number (based on the body length and burst time), duty cycle and fineness ratio (the body length over the largest thickness) on swimming performance (momentum capacity and the mass-specific cost of transport) are studied quantitatively. The results lead to a conclusion consistent with previous findings that a larval fish seldom swims in a burst-and-coast style. Given mass and swimming speed, a fish needs the least cost if it swims in a burst-and-coast style with a fineness ratio of 8.33. This energetically optimal fineness ratio is larger than that derived from the simple hydromechanical model proposed in literature. The calculated amount of energy saving in burst-and-coast swimming is comparable with the real-fish estimation in the literature. Finally, the predicted wake-vortex structures of both continuous and burst-and-coast swimming are biologically relevant.

Street Lines, US, 2015, NAVTEQ

Data.gov (United States)

U.S. Environmental Protection Agency — NAVTEQ Streets for the United States. The Streets layer contains all roads plus all Road Network attributes such as direction of travel, lanes, dividers, speed...

A Forced Damped Oscillation Framework for Undulatory Swimming Provides New Insights into How Propulsion Arises in Active and Passive Swimming

Science.gov (United States)

Bhalla, Amneet Pal Singh; Griffith, Boyce E.; Patankar, Neelesh A.

2013-01-01

A fundamental issue in locomotion is to understand how muscle forcing produces apparently complex deformation kinematics leading to movement of animals like undulatory swimmers. The question of whether complicated muscle forcing is required to create the observed deformation kinematics is central to the understanding of how animals control movement. In this work, a forced damped oscillation framework is applied to a chain-link model for undulatory swimming to understand how forcing leads to deformation and movement. A unified understanding of swimming, caused by muscle contractions (“active” swimming) or by forces imparted by the surrounding fluid (“passive” swimming), is obtained. We show that the forcing triggers the first few deformation modes of the body, which in turn cause the translational motion. We show that relatively simple forcing patterns can trigger seemingly complex deformation kinematics that lead to movement. For given muscle activation, the forcing frequency relative to the natural frequency of the damped oscillator is important for the emergent deformation characteristics of the body. The proposed approach also leads to a qualitative understanding of optimal deformation kinematics for fast swimming. These results, based on a chain-link model of swimming, are confirmed by fully resolved computational fluid dynamics (CFD) simulations. Prior results from the literature on the optimal value of stiffness for maximum speed are explained. PMID:23785272

A forced damped oscillation framework for undulatory swimming provides new insights into how propulsion arises in active and passive swimming.

Directory of Open Access Journals (Sweden)

Amneet Pal Singh Bhalla

Full Text Available A fundamental issue in locomotion is to understand how muscle forcing produces apparently complex deformation kinematics leading to movement of animals like undulatory swimmers. The question of whether complicated muscle forcing is required to create the observed deformation kinematics is central to the understanding of how animals control movement. In this work, a forced damped oscillation framework is applied to a chain-link model for undulatory swimming to understand how forcing leads to deformation and movement. A unified understanding of swimming, caused by muscle contractions ("active" swimming or by forces imparted by the surrounding fluid ("passive" swimming, is obtained. We show that the forcing triggers the first few deformation modes of the body, which in turn cause the translational motion. We show that relatively simple forcing patterns can trigger seemingly complex deformation kinematics that lead to movement. For given muscle activation, the forcing frequency relative to the natural frequency of the damped oscillator is important for the emergent deformation characteristics of the body. The proposed approach also leads to a qualitative understanding of optimal deformation kinematics for fast swimming. These results, based on a chain-link model of swimming, are confirmed by fully resolved computational fluid dynamics (CFD simulations. Prior results from the literature on the optimal value of stiffness for maximum speed are explained.

Sodium bicarbonate improves swimming performance.

Science.gov (United States)

Lindh, A M; Peyrebrune, M C; Ingham, S A; Bailey, D M; Folland, J P

2008-06-01

Sodium bicarbonate ingestion has been shown to improve performance in single-bout, high intensity events, probably due to an increase in buffering capacity, but its influence on single-bout swimming performance has not been investigated. The effects of sodium bicarbonate supplementation on 200 m freestyle swimming performance were investigated in elite male competitors. Following a randomised, double blind counterbalanced design, 9 swimmers completed maximal effort swims on 3 separate occasions: a control trial (C); after ingestion of sodium bicarbonate (SB: NaHCO3 300 mg . kg (-1) body mass); and after ingestion of a placebo (P: CaCO3 200 mg . kg (-1) body mass). The SB and P agents were packed in gelatine capsules and ingested 90 - 60 min prior to each 200 m swim. Mean 200 m performance times were significantly faster for SB than C or P (1 : 52.2 +/- 4.7; 1 : 53.7 +/- 3.8; 1 : 54.0 +/- 3.6 min : ss; p bicarbonate were all elevated pre-exercise in the SB compared to C and P trials (p < 0.05). Post-200 m blood lactate concentrations were significantly higher following the SB trial compared with P and C (p < 0.05). It was concluded that SB supplementation can improve 200 m freestyle performance time in elite male competitors, most likely by increasing buffering capacity.

Effect of panel shape of soccer ball on its flight characteristics

Science.gov (United States)

Hong, Sungchan; Asai, Takeshi

2014-05-01

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

An early record of ball lightning: Oliva (Spain), 1619

Science.gov (United States)

Domínguez-Castro, Fernando

2018-05-01

In a primary documentary source we found an early record of ball lightning (BL), which was observed in the monastery of Pi (Oliva, southeastern Spain) on 18 October 1619. The ball lightning was observed by at least three people and was described as a rolling burning vessel and a ball of fire. The ball lightning appeared following a lightning flash, showed a mainly horizontal motion, crossed a wall, smudged an image of the Lady of Rebollet (then known as Lady of Pi) and burnt her ruff, and overturned a cross.

Tracking of ball and players in beach volleyball videos.

Directory of Open Access Journals (Sweden)

Gabriel Gomez

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

Tracking of Ball and Players in Beach Volleyball Videos

Science.gov (United States)

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

2014-01-01

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

Supersymmetric dark-matter Q-balls and their interactions in matter

International Nuclear Information System (INIS)

Kusenko, Alexander; Loveridge, Lee C.; Shaposhnikov, Mikhail

2005-01-01

Supersymmetric extensions of the Standard Model contain nontopological solitons, Q-balls, which can be stable and can be a form of cosmological dark matter. Understanding the interaction of SUSY Q-balls with matter fermions is important for both astrophysical limits and laboratory searches for these dark-matter candidates. We show that a baryon scattering off a baryonic SUSY Q-ball can convert into its antiparticle with a high probability, while the baryon number of the Q-ball is increased by two units. For a SUSY Q-ball interacting with matter, this process dominates over those previously discussed in the literature

Energy savings in sea bass swimming in a school: measurements of tail beat frequency and oxygen consumption at different swimming speeds

DEFF Research Database (Denmark)

Herskin, J; Steffensen, JF

1998-01-01

Tail beat frequency of sea bass, Dicentrarchus labrax (L.) (23.5 ± 0·5 cm, LT), swimming at the front of a school was significantly higher than when swimming at the rear, for all water velocities tested from 14·8 to 32 cm s-1. The logarithm of oxygen consumption rate, and the tail beat frequency...... of solitary swimming sea bass (28·8 ± 0·4 cm, LT), were each correlated linearly with swimming speed, and also with one another. The tail beat frequency of individual fish was 9-14% lower when at the rear of a school than when at the front, corresponding to a 9-23% reduction in oxygen consumption rate....

Micro structrual characterization and analysis of ball milled silicon carbide

Science.gov (United States)

Madhusudan, B. M.; Raju, H. P.; Ghanaraja., S.

2018-04-01

Mechanical alloying has been one of the prominent methods of powder synthesis technique in solid state involving cyclic deformation, cold welding and fracturing of powder particles. Powder particles in this method are subjected to greater mechanical deformation due to the impact of ball-powder-ball and ball-powder-container collisions that occurs during mechanical alloying. Strain hardening and fracture of particles decreases the size of the particles and creates new surfaces. The objective of this Present work is to use ball milling of SiC powder for different duration of 5, 10, 15 and 20 hours by High energy planetary ball milling machine and to evaluate the effect of ball milling on SiC powder. Micro structural Studies using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and EDAX has been investigated.

[Swimming, physical activity and health: a historical perspective].

Science.gov (United States)

Conti, A A

2015-01-01

Swimming, which is the coordinated and harmonic movement of the human body inside a liquid medium by means of the combined action of the superior and inferior limbs, is a physical activity which is diffused throughout the whole world and it is practiced by healthy and non-healthy subjects. Swimming is one of the physical activities with less contraindications and, with limited exceptions, can be suggested to individuals of both sexes and of every age range, including the most advanced. Swimming requires energy both for the floating process and for the anterograde progression, with a different and variable osteo-arthro-muscular involvement according to the different styles. The energetic requirement is about four times that for running, with an overall efficiency inferior to 10%; the energetic cost of swimming in the female subject is approximately two thirds of that in the male subject. The moderate aerobic training typical of swimming is useful for diabetic and hypertensive individuals, for people with painful conditions of rachis, as also for obese and orthopaedic patients. Motor activity inside the water reduces the risk of muscular-tendinous lesions and, without loading the joints in excess, requires the harmonic activation of the whole human musculature. Swimming is an activity requiring multiple abilities, ranging from a sense of equilibrium to that of rhythm, from reaction speed to velocity, from joint mobility to resistance. The structured interest for swimming in the perspective of human health from the beginning of civilization, as described in this contribution, underlines the relevance attributed to this activity in the course of human history.

Street as Sustainable City Structural Element

Science.gov (United States)

Leyzerova, A. V.; Bagina, E. J.

2017-11-01

Sustainability in architecture is nowadays of particular significance in the course of globalization and information density. The technospehere spontaneous development poses a threat to the sustainability of traditional urban forms where a street is one of the essential forming elements in the urban structure. The article proposes to consider formally compositional street features in relation to one of the traditional streets in the historic center of Ekaterinburg. The study examines the street-planning structure, the development of its skeleton elements, silhouette and fabric elevation characteristics as well as the scale characteristics and visual complexity of objects. The study provided architectural and artistic aspects of street sustainability, and limits of the appropriate scale and composition consistency under which the compatibility of alternative compositional forms existing at different times is possible.

Street Prostitution Zones and Crime

OpenAIRE

Bisschop, Paul; Kastoryano, Stephen; van der Klaauw, Bas

2015-01-01

This paper studies the effects of introducing legal street prostitution zones on both registered and perceived crime. We exploit a unique setting in the Netherlands where legal street prostitution zones were opened in nine cities under different regulation systems. We provide evidence that the opening of these zones was not in response to changes in crime. Our difference-in-difference analysis using data on the largest 25 Dutch cities between 1994 and 2011 shows that opening a legal street pr...

A meta-analysis of steady undulatory swimming

NARCIS (Netherlands)

van Weerden, J. Fransje; Reid, Daniel A. P.; Hemelrijk, Charlotte K.

The mechanics underlying undulatory swimming are of great general interest, both to biologists and to engineers. Over the years, more data of the kinematics of undulatory swimming have been reported. At present, an integrative analysis is needed to determine which general relations hold between

Water Bouncing Balls: how material stiffness affects water entry

Science.gov (United States)

Truscott, Tadd

2014-03-01

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

Neutrons and the crystal ball experiments

International Nuclear Information System (INIS)

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

1997-01-01

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

The key kinematic determinants of undulatory underwater swimming at maximal velocity.

Science.gov (United States)

Connaboy, Chris; Naemi, Roozbeh; Brown, Susan; Psycharakis, Stelios; McCabe, Carla; Coleman, Simon; Sanders, Ross

2016-01-01

The optimisation of undulatory underwater swimming is highly important in competitive swimming performance. Nineteen kinematic variables were identified from previous research undertaken to assess undulatory underwater swimming performance. The purpose of the present study was to determine which kinematic variables were key to the production of maximal undulatory underwater swimming velocity. Kinematic data at maximal undulatory underwater swimming velocity were collected from 17 skilled swimmers. A series of separate backward-elimination analysis of covariance models was produced with cycle frequency and cycle length as dependent variables (DVs) and participant as a fixed factor, as including cycle frequency and cycle length would explain 100% of the maximal swimming velocity variance. The covariates identified in the cycle-frequency and cycle-length models were used to form the saturated model for maximal swimming velocity. The final parsimonious model identified three covariates (maximal knee joint angular velocity, maximal ankle angular velocity and knee range of movement) as determinants of the variance in maximal swimming velocity (adjusted-r2 = 0.929). However, when participant was removed as a fixed factor there was a large reduction in explained variance (adjusted r2 = 0.397) and only maximal knee joint angular velocity continued to contribute significantly, highlighting its importance to the production of maximal swimming velocity. The reduction in explained variance suggests an emphasis on inter-individual differences in undulatory underwater swimming technique and/or anthropometry. Future research should examine the efficacy of other anthropometric, kinematic and coordination variables to better understand the production of maximal swimming velocity and consider the importance of individual undulatory underwater swimming techniques when interpreting the data.

Intra-abdominal pressure during swimming.

Science.gov (United States)

Moriyama, S; Ogita, F; Huang, Z; Kurobe, K; Nagira, A; Tanaka, T; Takahashi, H; Hirano, Y

2014-02-01

The present study aimed to determine the intra-abdominal pressure during front crawl swimming at different velocities in competitive swimmers and to clarify the relationships between stroke indices and changes in intra-abdominal pressure. The subjects were 7 highly trained competitive collegiate male swimmers. Intra-abdominal pressure was measured during front crawl swimming at 1.0, 1.2 and 1.4 m · s(-1) and during the Valsalva maneuver. Intra-abdominal pressure was taken as the difference between minimum and maximum values, and the mean of 6 stable front crawl stroke cycles was used. Stroke rate and stroke length were also measured as stroke indices. There were significant differences in stroke rate among all velocities (P pressure and stroke rate or stroke length (P pressure and stroke indices when controlling for swimming velocity. These findings do not appear to support the effectiveness of trunk training performed by competitive swimmers aimed at increasing intra-abdominal pressure. © Georg Thieme Verlag KG Stuttgart · New York.

BALL KINEMATICS IN FINE POLISHING BETWEEN MISALIGNED DISKS IN CONIC OPENINGS

Directory of Open Access Journals (Sweden)

K. G. Shchetnikovich

2009-01-01

Full Text Available The paper considers ball kinematics in polishing between misaligned disks rotating with equal angular velocity; one of these disks has conic openings. Analytical dependences have been obtained for calculation of an angular velocity and ball sliding speed in the conic opening. It has been revealed that at a constant contact of a ball with elastic coating of a flat disk and absence of vibrations in the technological system an instantaneous axis of ball rotation does not change its position in the moving ball. It has been ascertained that when a ball is in contact with a flat disk having elastic coating with grooves changes in the position of ball rotation instantaneous axis have a regular character and do not depend on vibrations in the technological system.

Changes over swim lessons in parents' perceptions of children's supervision needs in drowning risk situations: "His swimming has improved so now he can keep himself safe".

Science.gov (United States)

Morrongiello, Barbara A; Sandomierski, Megan; Spence, Jeffrey R

2014-07-01

The aim of this longitudinal study was to determine how children's participation in swim lessons impacts parents' appraisals of children's drowning risk and need for supervision. Parents with 2-5-year old children enrolled in community swim lessons completed the same survey measures up to 4 times over an 8-month period. Multilevel regression analyses examining temporal relationships between parents' perceptions of their child's swim ability, supervision needs around water, and children's ability to keep themselves safe in drowning risk situations revealed that as children progressed through swim lessons, parents' perceptions of their child's swim ability and their belief that children are capable of keeping themselves safe around water increased. Further, the relation between parents' perceptions of swim ability and judgments of children's supervision needs was mediated through parents' judgment about their child's ability to secure their own safety near water. As parents perceive their child to be accumulating swim skills, they increasingly believe that children are capable of keeping themselves from drowning, and as a result, that less active parent supervision of their child is necessary. Implications of these findings for intervention efforts to counter this unwelcome way of thinking that may arise through continued participation in swim lessons are discussed. Incorporating a parent-focused component into children's learn-to-swim programs to promote more realistic appraisals of children's supervision needs and drowning risks may further enhance the positive benefits that swim lessons have for children's safety.

Swimming Pool Safety

Science.gov (United States)

... Spread the Word Shop AAP Find a Pediatrician Safety & Prevention Immunizations All Around At Home At Play ... Español Text Size Email Print Share Swimming Pool Safety Page Content ​What is the best way to ...

TECHNIQUE AND METHODOLOGY OF TRAINING IN SWIMMING CRAWL

Directory of Open Access Journals (Sweden)

Selim Alili

2013-07-01

Full Text Available The paper shows the technique and methodology training crawl swimming. Developed: the position of the head and body, footwork, hand movements, exercises for training footwork training drills and exercises for improving coordination technique on dry land and in water. Stated that accomplishes this swimmer swimming technique allows fast and is the fastest discipline. Therefore we can say that it is a favorite way of swimming and a pleasure to watch on the big stage.

Evaluation of swimming capability and potential velocity barrier problems for fish. Part B: New telemetric approaches to the assessment of fish swimming performance

International Nuclear Information System (INIS)

Scruton, D. A.; Goosney, R. G.; McKinley, R. S.; Booth, R. K.; Colavecchia, M.

1998-08-01

This report represents the second part of a study undertaken to develop information related to swimming capability of several important fish species. The study will provide biological design criteria to mitigate potential velocity barrier problems associated with hydroelectric power plants. This part of the report focuses on the development and evaluation of approaches to assessing locomotory activity, swimming performance and energy load costs to fish under naturally occurring conditions and in relation to potential barriers. The study involved implantation of a bio-sensitive radio transmitter (electromyogram (EMG)) tag in the swimming muscle of fish, calibration of locomotory ability and energetic scope, and subsequent use of EMG signals to assess swimming performance and metabolic costs in situ. Digital signal processing (DSP) with antennae switching was also used to study high speed swimming performance, behaviour, and migratory strategy in relation to ascent of an experimental flume. The techniques and technologies developed indicate the complexity of factors that regulate fish swimming energy expenditure that need to be considered in the design and operation of fish passage facilities. 84 refs., 6 tabs., figs., 2 appendices

SWIM (Soil and Water Integrated Model)

Energy Technology Data Exchange (ETDEWEB)

Krysanova, V; Wechsung, F; Arnold, J; Srinivasan, R; Williams, J

2000-12-01

The model SWIM (Soil and Water Integrated Model) was developed in order to provide a comprehensive GIS-based tool for hydrological and water quality modelling in mesoscale and large river basins (from 100 to 10,000 km{sup 2}), which can be parameterised using regionally available information. The model was developed for the use mainly in Europe and temperate zone, though its application in other regions is possible as well. SWIM is based on two previously developed tools - SWAT and MATSALU (see more explanations in section 1.1). The model integrates hydrology, vegetation, erosion, and nutrient dynamics at the watershed scale. SWIM has a three-level disaggregation scheme 'basin - sub-basins - hydrotopes' and is coupled to the Geographic Information System GRASS (GRASS, 1993). A robust approach is suggested for the nitrogen and phosphorus modelling in mesoscale watersheds. SWIM runs under the UNIX environment. Model test and validation were performed sequentially for hydrology, crop growth, nitrogen and erosion in a number of mesoscale watersheds in the German part of the Elbe drainage basin. A comprehensive scheme of spatial disaggregation into sub-basins and hydrotopes combined with reasonable restriction on a sub-basin area allows performing the assessment of water resources and water quality with SWIM in mesoscale river basins. The modest data requirements represent an important advantage of the model. Direct connection to land use and climate data provides a possibility to use the model for analysis of climate change and land use change impacts on hydrology, agricultural production, and water quality. (orig.)

Pacing in Swimming: A Systematic Review.

Science.gov (United States)

McGibbon, Katie E; Pyne, D B; Shephard, M E; Thompson, K G

2018-03-20

Pacing strategy, or how energy is distributed during exercise, can substantially impact athletic performance and is considered crucial for optimal performance in many sports. This is particularly true in swimming given the highly resistive properties of water and low mechanical efficiency of the swimming action. The aim of this systematic review was to determine the pacing strategies utilised by competitive swimmers in competition and their reproducibility, and to examine the impact of different pacing strategies on kinematic, metabolic and performance variables. This will provide valuable and practical information to coaches and sports science practitioners. The databases Web of Science, Scopus, SPORTDiscus and PubMed were searched for published articles up to 1 August 2017. A total of 23 studies examining pool-based swimming competitions or experimental trials in English-language and peer-reviewed journals were included in this review. In short- and middle-distance swimming events maintenance of swimming velocity is critical, whereas in long-distance events a low lap-to-lap variability and the ability to produce an end spurt in the final lap(s) are key. The most effective strategy in the individual medley (IM) is to conserve energy during the butterfly leg to optimise performance in subsequent legs. The pacing profiles of senior swimmers remain relatively stable irrespective of opponents, competition stage or type, and performance time. Implementing event-specific pacing strategies should benefit the performance of competitive swimmers. Given differences between swimmers, there is a need for greater individualisation when considering pacing strategy selection across distances and strokes.

Mechanical Study of Standard Six Beat Front Crawl Swimming by Using Swimming Human Simulation Model

Science.gov (United States)

Nakashima, Motomu

There are many dynamical problems in front crawl swimming which have not been fully investigated by analytical approaches. Therefore, in this paper, standard six beat front crawl swimming is analyzed by the swimming human simulation model SWUM, which has been developed by the authors. First, the outline of the simulation model, the joint motion for one stroke cycle, and the specifications of calculation are described respectively. Next, contribution of each fluid force component and of each body part to the thrust, effect of the flutter kick, estimation of the active drag, roll motion, and the propulsive efficiency are discussed respectively. The following results were theoretically obtained: The thrust is produced at the upper limb by the normal drag force component. The flutter kick plays a role in raising the lower half of the body. The active drag coefficient in the simulation becomes 0.082. Buoyancy determines the primal wave of the roll motion fluctuation. The propulsive efficiency in the simulation becomes 0.2.

Swimming as physical activity and recreation for women

Directory of Open Access Journals (Sweden)

Yfanti Maria

2014-01-01

Full Text Available The present study reviews all data that establish swimming as an everyday lifestyle and recreational activity for women, since it promotes wellness, well-being and longevity. Swimming as a natural, physical activity is one of the most effective ways of exercise, since it affects and work outs the whole body. It is the most suitable sport for all age groups, because it combines beneficial results, for both body and soul and is also a low-risk-injury physical exercise. Aim of this study is to record the effect of recreational swimming in physical condition indexes and in quality of life in women. In particular to record the benefits, since studies have shown that swimming can help in prevention and treatment of chronic diseases and improves quality of life, of well-being and longevity. Results of all studies showed that swimming, as a great natural recreational activity has multiple beneficial effects on the female body that are not limited to the physical characteristics but are extended to the mental ones. Challenges for the application and development fields of this particular method of exercise, are the quality of service provided and the staffing of departments and programs in multiple carriers, private or public. Researchers and writers agree that there are great prospects for growth for women through partnerships, with programs and systematic research in the field of recreational swimming.

Predictors of Swimming Ability among Children and Adolescents in the United States

Directory of Open Access Journals (Sweden)

Jennifer Pharr

2018-02-01

Full Text Available Swimming is an important source of physical activity and a life skill to prevent drowning. However, little research has been conducted to understand predictors of swimming ability. The purpose of this study was to understand factors that predict swimming ability among children and adolescents in the United States (US. This was a cross-sectional survey conducted between February and April of 2017 across five geographically diverse cities. Participants were accessed through the Young Christian Men’s Association (YMCA and included parents of children aged 4–11 years old and adolescents aged 12–17 years old. Independent t-test, analysis of variance (ANOVA, and univariate and multivariate analyses were conducted. Several factors were significant (p ≤ 0.05 predictors of swimming ability and explained 53% of the variance in swimming ability. Variables that were positively associated with swimming ability included: ability of parent(s to swim, child/adolescent age, a best friend who enjoys swimming, water-safety knowledge, pool open all year, and encouragement to swim from parent(s. Variables that were negatively associated with swimming ability included: fear of drowning, being African American, and being female. Interventions and programs to improve the swimming ability of children and adolescents could be developed with these predictors in mind.

Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

Energy Technology Data Exchange (ETDEWEB)

Meng, Li

2011-05-04

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

Swimming training induces liver mitochondrial adaptations to oxidative stress in rats submitted to repeated exhaustive swimming bouts.

Directory of Open Access Journals (Sweden)

Frederico D Lima

Full Text Available BACKGROUND AND AIMS: Although acute exhaustive exercise is known to increase liver reactive oxygen species (ROS production and aerobic training has shown to improve the antioxidant status in the liver, little is known about mitochondria adaptations to aerobic training. The main objective of this study was to investigate the effects of the aerobic training on oxidative stress markers and antioxidant defense in liver mitochondria both after training and in response to three repeated exhaustive swimming bouts. METHODS: Wistar rats were divided into training (n = 14 and control (n = 14 groups. Training group performed a 6-week swimming training protocol. Subsets of training (n = 7 and control (n = 7 rats performed 3 repeated exhaustive swimming bouts with 72 h rest in between. Oxidative stress biomarkers, antioxidant activity, and mitochondria functionality were assessed. RESULTS: Trained group showed increased reduced glutathione (GSH content and reduced/oxidized (GSH/GSSG ratio, higher superoxide dismutase (MnSOD activity, and decreased lipid peroxidation in liver mitochondria. Aerobic training protected against exhaustive swimming ROS production herein characterized by decreased oxidative stress markers, higher antioxidant defenses, and increases in methyl-tetrazolium reduction and membrane potential. Trained group also presented higher time to exhaustion compared to control group. CONCLUSIONS: Swimming training induced positive adaptations in liver mitochondria of rats. Increased antioxidant defense after training coped well with exercise-produced ROS and liver mitochondria were less affected by exhaustive exercise. Therefore, liver mitochondria also adapt to exercise-induced ROS and may play an important role in exercise performance.

BLEACHING NEPTUNE BALLS

Directory of Open Access Journals (Sweden)

BONET Maria Angeles

2014-05-01

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

Shape Optimization of Swimming Sheets

Energy Technology Data Exchange (ETDEWEB)

Wilkening, J.; Hosoi, A.E.

2005-03-01

The swimming behavior of a flexible sheet which moves by propagating deformation waves along its body was first studied by G. I. Taylor in 1951. In addition to being of theoretical interest, this problem serves as a useful model of the locomotion of gastropods and various micro-organisms. Although the mechanics of swimming via wave propagation has been studied extensively, relatively little work has been done to define or describe optimal swimming by this mechanism.We carry out this objective for a sheet that is separated from a rigid substrate by a thin film of viscous Newtonian fluid. Using a lubrication approximation to model the dynamics, we derive the relevant Euler-Lagrange equations to optimize swimming speed and efficiency. The optimization equations are solved numerically using two different schemes: a limited memory BFGS method that uses cubic splines to represent the wave profile, and a multi-shooting Runge-Kutta approach that uses the Levenberg-Marquardt method to vary the parameters of the equations until the constraints are satisfied. The former approach is less efficient but generalizes nicely to the non-lubrication setting. For each optimization problem we obtain a one parameter family of solutions that becomes singular in a self-similar fashion as the parameter approaches a critical value. We explore the validity of the lubrication approximation near this singular limit by monitoring higher order corrections to the zeroth order theory and by comparing the results with finite element solutions of the full Stokes equations.

Guide for decontaminating swimming pool at schools

International Nuclear Information System (INIS)

Matsuhashi, Shimpei; Kurikami, Hiroshi; Yasuda, Ryo; Takano, Takao; Seko, Noriaki; Naganawa, Hirochika; Kuroki, Ryota; Saegusa, Jun

2012-07-01

Because of TEPCO Fukushima Dai-ichi Nuclear Power Plant accident due to the Great East Japan Earthquake, a huge amount of radioactive materials was widely dispersed and precipitated into the environment. Swimming pools in Fukushima prefectures were contaminated with the radioactives. We JAEA carried out several demonstration tests to decontaminate the radioactives and discharge the pool water safely. We concluded the results obtained from the tests as 'Guide for decontaminating Swimming Pool at School' and released it quickly. Following this, we also released the guide in English. This manuscript, as an experimental report of the swimming pool water decontamination, is consisted from the guide in Japanese and English prepared. (author)

Guide for decontaminating swimming pool at schools

Energy Technology Data Exchange (ETDEWEB)

Matsuhashi, Shimpei; Kurikami, Hiroshi; Yasuda, Ryo; Takano, Takao; Seko, Noriaki; Naganawa, Hirochika; Kuroki, Ryota; Saegusa, Jun

2012-07-15

Because of TEPCO Fukushima Dai-ichi Nuclear Power Plant accident due to the Great East Japan Earthquake, a huge amount of radioactive materials was widely dispersed and precipitated into the environment. Swimming pools in Fukushima prefectures were contaminated with the radioactives. We JAEA carried out several demonstration tests to decontaminate the radioactives and discharge the pool water safely. We concluded the results obtained from the tests as 'Guide for decontaminating Swimming Pool at School' and released it quickly. Following this, we also released the guide in English. This manuscript, as an experimental report of the swimming pool water decontamination, is consisted from the guide in Japanese and English prepared. (author)

Effect of swimming suit design on the energy demands of swimming.

Science.gov (United States)

Starling, R D; Costill, D L; Trappe, T A; Jozsi, A C; Trappe, S W; Goodpaster, B H

1995-07-01

Eight competitive male swimmers completed a standardized 365.8 m (400 yd) freestyle swimming trial at a fixed pace (approximately 90% of maximal effort) while wearing a torso swim suit (TOR) or a standard racing suit (STD). Oxygen uptake (VO2), blood lactate, heart rate (HR), and distance per stroke (DPS) measurements were obtained. In addition, a video-computer system was used to collect velocity data during a prone underwater glide following a maximal leg push-off from the side of the pool while wearing the TOR and STD suits. These data were used to calculate the total distance covered during the glides. VO2 (3.76 +/- 0.16 vs 3.92 +/- 0.18 l.min-1) and lactate (8.08 +/- 0.53 vs, 9.66 +/- 0.66 mM) were significantly (P 0.05) between the TOR (170.1 +/- 5.1 b.min-1) and STD (173.5 +/- 5.7 b.min-1) trials. DPS was significantly greater during the TOR (2.70 +/- 0.066 m.stroke-1) versus STD (2.58 +/- 0.054 m.stroke-1) trial. A significantly greater total distance was covered during the prone glide while wearing the TOR (2.05 +/- 0.067 m) compared to the STD (2.00 +/- 0.080 m) suit. These findings demonstrate that a specially designed torso suit reduces the energy demand of swimming compared to a standard racing suit which may be due to a reduction in body drag.

76 FR 60732 - Drawbridge Operation Regulations; Navesink (Swimming) River, NJ

Science.gov (United States)

2011-09-30

... Operation Regulations; Navesink (Swimming) River, NJ AGENCY: Coast Guard, DHS. ACTION: Notice of temporary... (Swimming) River between Oceanic and Locust Point, New Jersey. The deviation is necessary to facilitate...: The Oceanic Bridge, across the Navesink (Swimming) River, mile 4.5, between Oceanic and Locust Point...

Stability of a Fermi ball against deformation from spherical shape

International Nuclear Information System (INIS)

Yoshida, T.; Ogure, K.; Arafune, J.

2003-01-01

The stability of a Fermi ball (F ball), which is a kind of nontopological soliton accompanying the breakdown of the approximate Z 2 symmetry, is investigated in three situations: when it is electrically neutral, when it is electrically charged and unscreened, and when it is electrically charged and screened. We argue only that the third case is physically meaningful since the neutral F ball is unstable and the case of an unscreened charged F ball is observationally excluded when it has a sizable contribution to CDM. We find that the energy scale of the breakdown of the approximate Z 2 symmetry v should satisfy v 6 GeV if the F ball is the main component of CDM

Cleaning up the Streets of Denver

International Nuclear Information System (INIS)

Stegen, R.L.; Wood, T.R.; Hackett, J.R.; Sogue, A.

2006-01-01

Between 1913 and 1924, several Denver area facilities extracted radium from carnotite ore mined from the Paradox basin region of Colorado. Tailings or abandoned ores from these facilities were apparently incorporated into asphalt used to pave approximately 7.2 kilometers (4.5 miles) of streets in Denver. A majority of the streets are located in residential areas. The radionuclides are bound within the asphalt matrix and pose minimal risk unless they are disturbed. The City and County of Denver (CCoD) is responsible for controlling repairs and maintenance on these impacted streets. Since 2002, the CCoD has embarked on a significant capital improvement project to remove the impacted asphalt for secure disposal followed by street reconstruction. To date, Parsons has removed approximately 55 percent of the impacted asphalt. This paper discusses the history of the Denver Radium Streets and summarizes on-going project efforts. (authors)

Soccer Ball Lift Coefficients via Trajectory Analysis

Science.gov (United States)

Goff, John Eric; Carre, Matt J.

2010-01-01

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

The effect of intermediate stop and ball size in fabrication of recycled steel powder using ball milling from machining steel chips

International Nuclear Information System (INIS)

Fitri, M.W.M.; Shun, C.H.; Rizam, S.S.; Shamsul, J.B.

2007-01-01

A feasibility study for producing recycled steel powder from steel scrap by ball milling was carried out. Steel scrap from machining was used as a raw material and was milled using planetary ball milling. Three samples were prepared in order to study the effect of intermediate stop and ball size. Sample with intermediate stop during milling process showed finer particle size compared to the sample with continuous milling. Decrease in the temperature of the vial during the intermediate stop milling gives less ductile behaviour to the steel powder, which is then easily work-hardened and fragmented to fine powder. Mixed small and big size ball give the best production of recycled steel powder where it gives higher impact force to the scrap and accelerate the fragmentation of the steel scrap into powder. (author)

EFFECTS OF THREE FEEDBACK CONDITIONS ON AEROBIC SWIM SPEEDS

Directory of Open Access Journals (Sweden)

Pedro Pérez Soriano

2009-03-01

Full Text Available The purpose of this study was twofold: (a to develop an underwater chronometer capable to provide feedback while the athlete is swimming, as well as being a control tool for the coach, and (b to analyse its feedback effect on swim pace control compared with feedback provided by the coach and with no feedback, in 25 m and 50 m swimming pools. 30 male swimmers of national level volunteer to participate. Each swimmer swam 3 x 200 m at aerobic speed (AS and 3 x 200 m just under the anaerobic threshold speed (AnS, each swam repetition with a different feedback condition: chronometer, coach and without feedback. Results (a validate the chronometer system developed and (b show that swimmers pace control is affected by the type of feedback provided, the swim speed elected and the size of the swimming pool

Analysis of the swimming velocity of cadmium-stressed Daphnia magna

International Nuclear Information System (INIS)

Baillieul, M.; Blust, R.

1999-01-01

The swimming velocity of the waterflea Daphnia magna is dependent on its body size. Therefore, environmental factors like toxic stress that influence growth also influence swimming velocity. An experiment was set up to test whether exposure to cadmium would reduce only growth, with a concomitant decrease in velocity, or whether it would reduce velocity below the swimming velocity of similarly-sized control animals. Daphnids were exposed for 10 days to free cadmium ion concentrations ranging from 1x10 -8 to 1x10 -7 M Cd 2+ , and body size and swimming velocity were measured every 2 days. The results showed that cadmium decreased both growth and velocity, i.e. exposed daphnids swam slower than similarly-sized control daphnids. Swimming velocity provided no indication of successful acclimation in any cadmium treatment. Food consumption and assimilation were reduced by exposure to cadmium. This reduced food intake may have, at least partially, caused the decreased growth rates. However, since reduced food intake does not affect swimming velocity, the reduced swimming velocity must be attributed to toxic effects of cadmium, other than those on food intake. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Research on Relative Age in Hungarian Swimming

Directory of Open Access Journals (Sweden)

Nagy Nikoletta

2015-12-01

Full Text Available In 2017, the 19th World Swimming Championship will be organized in Hungary. Up to now, many people have already been working with swimmers to achieve good results. However, in the next period they must work even harder to ensure that the national swimmers of a country as small as Hungary can achieve the outstanding results of their predecessors. Since high-level competitions in swimming have become more intense, innovations including scientific studies are needed during preparation for the event. The purpose of this paper is to present the major results of an independent study carried out by the authors about the relative age of the best Hungarian swimmers with the aim of contributing to their preparation. The research population consisted of selected age groups of swimmers registered by the Hungarian Swimming Association (N=400. The method for data collection was an analysis of documents. To evaluate the data, the Chi-square and Kruskal-Wallis tests were used. The results are presented according to the period of the competitor’s date of birth, gender, and age group. The results confirm only partly the hypothesis that people born in the first quarters of the year play a dominant role in Hungarian national swimming teams. In the conclusion, the authors recommend further research on relative age in swimming and in other sports.

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

Directory of Open Access Journals (Sweden)

Katharine L. Wickington

2017-02-01

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

Infections Unlikely to be Spread Through Swimming Pools

Science.gov (United States)

... Water Home Infections Unlikely to be Spread Through Swimming Pools Language: English (US) Español (Spanish) Recommend on ... included below. Infections Unlikely to be Spread by Swimming Pools Head Lice Head lice are unlikely to ...

Street level society

DEFF Research Database (Denmark)

Vinum, Christine; Nissen, Morten

2006-01-01

This paper aims to reflect on research findings from different empirical studies of social work with young drug users and socially excluded young people in Copenhagen. In the paper we account for historical changes in social policy and interventions into young people's drug taking in Copenhagen......, and partly from the decentralizing and specializing efforts characteristic of the Danish welfare state and its institutions. We discuss a general turn towards street level interventions to address the problems of social exclusion, as well as different attempts to create what we term street level heterotopias...

THE EFFECTS OF DIFFERENT MODELS OF SWIMMING TRAINING (DEFINED IN RELATION TO ANAEROBIC THRESHOLD ON THE INCREASE OF SWIM SPEED

Directory of Open Access Journals (Sweden)

Dragan Krivokapić

2007-05-01

Full Text Available On the sample of 32 fourth grade students of some Belgrade highs schools, who had the physical education classes carried out at the city’s swimming pools, an attempt was made to evaluate the effects of the two different programmes of swimming training in different intensity zones, defi ned relative to the anaerobic threshold. The examinees were divided into two groups out of 15 i.e. 17 participants who were not (according to statistics signifi cantly different in terms of average time and heart frequency during the 400 m swimming test and heart frequency and time measured after 50 m in the moment of reaching the anaerobic threshold. The fi rst training model consisted of swimming at the intensity level within the zone below anaerobic threshold, while the second model involved occasional swimming at a higher intensity sometimes surpassing the anaerobic threshold. The experimentalprogramme with both sub-groups lasted 8 weeks with 3 training sessions per week, 2 ‘of which we’re identical for both experimental groups, with the third one differing regarding the swimming intensity, this in the fi rst group being still in the zone below, and in the second group occasionally in the zone above the anaerobic threshold. The amount of training and the duration were the same in both programmes. The aim of the research , was to evaluate and to compare the effects of the two training models, using as the basic criteria possible changes of average time and heart frequency during the 400 m swimming test and heart frequency and time measured after 50 m in the moment of reaching the anaerobic thereshold. On the basis of the statistical analysis of the obtained data, it is possible to conclude that in both experimental groups there were statistically signifi cant changes of average values concerning all the physiological variables. Although the difference in effi ciency of applied experimental programmes is not defi ned, we can claim that both of experimental

Visualization of air flow around soccer ball using a particle image velocimetry

Science.gov (United States)

Hong, Sungchan; Asai, Takeshi; Seo, Kazuya

2015-10-01

A traditional soccer ball is constructed using 32 pentagonal and hexagonal panels. In recent years, however, the likes of the Teamgeist and Jabulani balls, constructed from 14 and 8 panels, respectively, have entered the field, marking a significant departure from conventionality in terms of shape and design. Moreover, the recently introduced Brazuca ball features a new 6-panel design and has already been adopted by many soccer leagues. However, the shapes of the constituent panels of these balls differ substantially from those of conventional balls. Therefore, this study set out to investigate the flight and aerodynamic characteristics of different orientations of the soccer ball, which is constructed from panels of different shapes. A wind tunnel test showed substantial differences in the aerodynamic forces acting on the ball, depending on its orientation. Substantial differences were also observed in the aerodynamic forces acting on the ball in different directions, corresponding to its orientation and rotation. Moreover, two-dimensional particle image velocimetry (2D-PIV) measurements showed that the boundary separation varies depending on the orientation of the ball. Based on these results, we can conclude that the shape of the panels of a soccer ball substantially affects its flight trajectory.

Hermitian harmonic maps into convex balls

International Nuclear Information System (INIS)

Li Zhenyang; Xi Zhang

2004-07-01

In this paper, we consider Hermitian harmonic maps from Hermitian manifolds into convex balls. We prove that there exist no non-trivial Hermitian harmonic maps from closed Hermitian manifolds into convex balls, and we use the heat flow method to solve the Dirichlet problem for Hermitian harmonic maps when the domain is compact Hermitian manifold with non-empty boundary. The case where the domain manifold is complete(noncompact) is also studied. (author)

Basic Land Drills for Swimming Stroke Acquisition

Science.gov (United States)

Zhang, Peng

2014-01-01

Teaching swimming strokes can be a challenging task in physical education. The purpose of the article is to introduce 12 on land drills that can be utilized to facilitate the learning of swimming strokes, including elementary back stroke, sidestroke, front crawl, back stroke, breaststroke, and butterfly. Each drill consists of four components…

Assessment of head injury of children due to golf ball impact.

Science.gov (United States)

Lee, Heow Pueh; Wang, Fang

2010-10-01

Head trauma injury due to impact by a flying golf ball is one of the most severe possible injury accidents on the golf course. Numerical simulations based on the finite element method are presented to investigate head injury in children due to impact by a flying golf ball. The stress and energy flow patterns in a head model during the golf ball impact are computed for various combinations of striking speed, falling angle of the golf ball before impact, and impact location. It is found that a child is more prone to head injury due to golf ball impact on the frontal and side/temporal areas. The simulated results are found to conform to the clinical reports on children's head injuries from flying golf balls.

Turtle mimetic soft robot with two swimming gaits.

Science.gov (United States)

Song, Sung-Hyuk; Kim, Min-Soo; Rodrigue, Hugo; Lee, Jang-Yeob; Shim, Jae-Eul; Kim, Min-Cheol; Chu, Won-Shik; Ahn, Sung-Hoon

2016-05-04

This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas. This flipper actuator can mimic the continuous deformation of the forelimb of Chelonia mydas which could not be realized in previous motor based robot. This actuator can also produce two distinct motions that correspond to the two different swimming gaits of the Chelonia mydas, which are the routine and vigorous swimming gaits, by changing the applied current sequence of the SMA wires embedded in the flipper actuator. The generated thrust and the swimming efficiency in each swimming gait of the flipper actuator were measured and the results show that the vigorous gait has a higher thrust but a relatively lower swimming efficiency than the routine gait. The flipper actuator was implemented in a biomimetic turtle robot, and its average swimming speed in the routine and vigorous gaits were measured with the vigorous gait being capable of reaching a maximum speed of 11.5 mm s(-1).

Ball check valve

International Nuclear Information System (INIS)

Bevilacqua, F.

1978-01-01

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

The development of cobalt-base alloy ball bearing

International Nuclear Information System (INIS)

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

1986-01-01

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

Air quality considerations for stormwater green street design.

Science.gov (United States)

Shaneyfelt, Kathryn M; Anderson, Andrew R; Kumar, Prashant; Hunt, William F

2017-12-01

Green streets are increasingly being used as a stormwater management strategy to mitigate stormwater runoff at its source while providing other environmental and societal benefits, including connecting pedestrians to the street. Simultaneously, human exposure to particulate matter from urban transportation is of major concern worldwide due to the proximity of pedestrians, drivers, and cyclists to the emission sources. Vegetation used for stormwater treatment can help designers limit the exposure of people to air pollutants. This goal can be achieved through the deliberate placement of green streets, along with strategic planting schemes that maximize pollutant dispersion. This communication presents general design considerations for green streets that combine stormwater management and air quality goals. There is currently limited guidance on designing green streets for air quality considerations; this is the first communication to offer suggestions and advice for the design of green stormwater streets in regards to their effects on air quality. Street characteristics including (1) the width to height ratio of the street to the buildings, (2) the type of trees and their location, and (3) any prevailing winds can have an impact on pollutant concentrations within the street and along sidewalks. Vegetation within stormwater control measures has the ability to reduce particulate matter concentrations; however, it must be carefully selected and placed within the green street to promote the dispersion of air flow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Warm-up and performance in competitive swimming.

Science.gov (United States)

Neiva, Henrique P; Marques, Mário C; Barbosa, Tiago M; Izquierdo, Mikel; Marinho, Daniel A

2014-03-01

Warm-up before physical activity is commonly accepted to be fundamental, and any priming practices are usually thought to optimize performance. However, specifically in swimming, studies on the effects of warm-up are scarce, which may be due to the swimming pool environment, which has a high temperature and humidity, and to the complexity of warm-up procedures. The purpose of this study is to review and summarize the different studies on how warming up affects swimming performance, and to develop recommendations for improving the efficiency of warm-up before competition. Most of the main proposed effects of warm-up, such as elevated core and muscular temperatures, increased blood flow and oxygen delivery to muscle cells and higher efficiency of muscle contractions, support the hypothesis that warm-up enhances performance. However, while many researchers have reported improvements in performance after warm-up, others have found no benefits to warm-up. This lack of consensus emphasizes the need to evaluate the real effects of warm-up and optimize its design. Little is known about the effectiveness of warm-up in competitive swimming, and the variety of warm-up methods and swimming events studied makes it difficult to compare the published conclusions about the role of warm-up in swimming. Recent findings have shown that warm-up has a positive effect on the swimmer's performance, especially for distances greater than 200 m. We recommend that swimmers warm-up for a relatively moderate distance (between 1,000 and 1,500 m) with a proper intensity (a brief approach to race pace velocity) and recovery time sufficient to prevent the early onset of fatigue and to allow the restoration of energy reserves (8-20 min).

Launch Creativity with Ping-Pong Ball Challenge

Science.gov (United States)

Kornoelje, Joanne; Roman, Harry T.

2011-01-01

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

Nonlinear dynamic model for skidding behavior of angular contact ball bearings

Science.gov (United States)

Han, Qinkai; Chu, Fulei

2015-10-01

A three-dimensional nonlinear dynamic model is proposed to predict the skidding behavior of angular contact ball bearings under combined load condition. The centrifugal and gyroscopic effects induced by ball rotation and revolution, Hertz contact between the ball and inner/outer races, discontinuous contact between the ball and cage and elastohydrodynamic lubrication are considered in the model. Through comparisons with the tested results of the reference, the dynamic model is verified. Based upon these, variations of ball slipping speed with time and space are discussed for the bearing under combined load condition. It is shown that radial load leads to the fluctuations in the slipping velocity of the ball contacting with inner/outer races, especially for the ball in load-decreasing regions. Adding the radial load would significantly increase the amplitude and range of slipping velocity, indicating that the skidding becomes more serious. As the ball still withstands contact load in the load-decreasing region, large slipping velocity would increase the temperature of both bearing and lubricant oil, intensify the wear and then might shorten the bearing service life. Therefore, the radial load should be considered carefully in the design and monitoring of rotating machinery.

Random power series in the unit ball of Cn

International Nuclear Information System (INIS)

Shi Jihuai.

1989-07-01

The random power series in the unit disc has been studied by many authors. In this paper, we studied the random power series in the unit ball of C n and generalized some results in the unit disc to the unit ball, in particular, the result obtained recently by Duren has been generalized to the unit ball. The main tool used here is the generalized Salem-Zygmund's theorem. (author). 12 refs

Presence and select determinants of organophosphate flame retardants in public swimming pools

International Nuclear Information System (INIS)

Teo, Tiffany L.L.; Coleman, Heather M.; Khan, Stuart J.

2016-01-01

The occurrence of five organophosphate flame retardants (PFRs) consisting of tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1.3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) in swimming pools were investigated. Fifteen chlorinated public swimming pools were sampled, including indoor pools, outdoor pools and spa pools. The analyses were carried out using isotope dilution gas chromatography tandem mass spectrometry. All five PFRs were detected in swimming pool waters with concentrations ranging from 5–27 ng/L (TNBP), 7–293 ng/L (TCEP), 62–1180 ng/L (TCIPP), 10–670 ng/L (TDCIPP) and 8–132 ng/L (TPHP). The concentrations of PFRs were generally higher in indoor swimming pools compared to outdoor swimming pools. In municipal water supplies, used to fill the swimming pools in three of the sampling locations, the five PFRs were all below the limit of quantifications, eliminating this as the source. Potential leaching of PFRs from commonly used swimming equipment, including newly purchased kickboards and swimsuits was investigated. These experiments revealed that PFRs leached from swimsuits, and may be a source of PFRs in swimming pools. A quantitative risk assessment revealed that the health risk to PFRs via swimming pools was generally low and below commonly applied health risk benchmarks. - Highlights: • TNBP, TCEP, TCIPP, TDCIPP and TPHP were detected in chlorinated swimming pools. • PFRs were below the LOQ in fill water samples collected from 3 locations. • TCIPP was observed to have the highest concentrations in swimming pools. • PFRs are leaching from swimsuits and may be a source in swimming pools. • Health risks through oral and dermal exposure to PFRs in swimming pools were low.

Presence and select determinants of organophosphate flame retardants in public swimming pools

Energy Technology Data Exchange (ETDEWEB)

Teo, Tiffany L.L., E-mail: tiffany.teo@unsw.edu.au [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Kensington NSW 2052 (Australia); Coleman, Heather M., E-mail: h.coleman@ulster.ac.uk [Nanotechnology and Integrated BioEngineering Centre, School of Engineering, University of Ulster, Jordanstown, County Antrim BT37 0QB, Northern Ireland (United Kingdom); Khan, Stuart J., E-mail: s.khan@unsw.edu.au [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Kensington NSW 2052 (Australia)

2016-11-01

The occurrence of five organophosphate flame retardants (PFRs) consisting of tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1.3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) in swimming pools were investigated. Fifteen chlorinated public swimming pools were sampled, including indoor pools, outdoor pools and spa pools. The analyses were carried out using isotope dilution gas chromatography tandem mass spectrometry. All five PFRs were detected in swimming pool waters with concentrations ranging from 5–27 ng/L (TNBP), 7–293 ng/L (TCEP), 62–1180 ng/L (TCIPP), 10–670 ng/L (TDCIPP) and 8–132 ng/L (TPHP). The concentrations of PFRs were generally higher in indoor swimming pools compared to outdoor swimming pools. In municipal water supplies, used to fill the swimming pools in three of the sampling locations, the five PFRs were all below the limit of quantifications, eliminating this as the source. Potential leaching of PFRs from commonly used swimming equipment, including newly purchased kickboards and swimsuits was investigated. These experiments revealed that PFRs leached from swimsuits, and may be a source of PFRs in swimming pools. A quantitative risk assessment revealed that the health risk to PFRs via swimming pools was generally low and below commonly applied health risk benchmarks. - Highlights: • TNBP, TCEP, TCIPP, TDCIPP and TPHP were detected in chlorinated swimming pools. • PFRs were below the LOQ in fill water samples collected from 3 locations. • TCIPP was observed to have the highest concentrations in swimming pools. • PFRs are leaching from swimsuits and may be a source in swimming pools. • Health risks through oral and dermal exposure to PFRs in swimming pools were low.

Simulated front crawl swimming performance related to critical speed and critical power.

Science.gov (United States)

Toussaint, H M; Wakayoshi, K; Hollander, A P; Ogita, F

1998-01-01

Competitive pool swimming events range in distance from 50 to 1500 m. Given the difference in performance times (+/- 23-1000 s), the contribution of the aerobic and anaerobic energy systems changes considerably with race distance. In training practice the regression line between swimming distance and time (Distance = critical velocity x time + anaerobic swimming capacity) is used to determine the individual capacity of the aerobic and anaerobic metabolic pathways. Although there is confidence that critical velocity and anaerobic swimming capacity are fitness measures that separate aerobic and anaerobic components, a firm theoretical basis for the interpretation of these results does not exist. The purpose of this study was to evaluate the critical power concept and anaerobic swimming capacity as measures of the aerobic and anaerobic capacity using a modeling approach. A systems model was developed that relates the mechanics and energetics involved in front crawl swimming performance. From actual swimming flume measurements, the time dependent aerobic and anaerobic energy release was modeled. Data derived from the literature were used to relate the energy cost of front crawl swimming to swimming velocity. A balance should exist between the energy cost to swim a distance in a certain time and the concomitant aerobic and anaerobic energy release. The ensuing model was used to predict performance times over a range of distances (50-1500 m) and to calculate the regression line between swimming distance and time. Using a sensitivity analysis, it was demonstrated that the critical velocity is indicative for the capacity of the aerobic energy system. Estimates of the anaerobic swimming capacity, however, were influenced by variations in both anaerobic and aerobic energy release. Therefore, it was concluded that the anaerobic swimming capacity does not provide a reliable estimate of the anaerobic capacity.

Biochemical and hematological changes following the 120-km open-water marathon swim.

Science.gov (United States)

Drygas, Wojciech; Rębowska, Ewa; Stępień, Ewa; Golański, Jacek; Kwaśniewska, Magdalena

2014-09-01

Data on physiological effects and potential risks of a ultraendurance swimming are scarce. This report presents the unique case of a 61-year old athlete who completed a non-stop open-water 120-km ultramarathon swim on the Warta River, Poland. Pre-swimming examinations revealed favorable conditions (blood pressure, 110/70 mmHg; rest heart rate, 54 beats/minute, ejection fraction, 60%, 20.2 metabolic equivalents in a maximal exercise test). The swimming time and distance covered were 27 h 33 min and 120 km, respectively. Blood samples for hematological and biochemical parameters were collected 30 min, 4 hrs, 10 hrs and 8 days after the swim. The body temperature of the swimmer was 36.7°C before and 35.1°C after the swim. The hematological parameters remained within the reference range in the postexercise period except for leucocytes (17.5 and 10.6 x G/l noted 30 minutes and 4 hours after the swim, respectively). Serum urea, aspartate aminotransferase and C-reactive protein increased above the reference range reaching 11.3 mmol/l, 1054 nmol/l/s and 25.9 mg/l, respectively. Symptomatic hyponatremia was not observed. Although the results demonstrate that an experienced athlete is able to complete an ultra-marathon swim without negative health consequences, further studies addressing the potential risks of marathon swimming are required. Key pointsData on biochemical changes due to long-distance swimming are scarce.This report presents the unique case of a 61-year old athlete who completed a non-stop open-water 120-km ultramarathon swim.An experienced athlete is able to complete an ultra-marathon swim without serious health consequences.Regarding the growing popularity of marathon swimming further studies addressing the potential risks of such exhaustive exercise are required.

Air quality considerations for stormwater green street design

International Nuclear Information System (INIS)

Shaneyfelt, Kathryn M.; Anderson, Andrew R.; Kumar, Prashant; Hunt, William F.

2017-01-01

Green streets are increasingly being used as a stormwater management strategy to mitigate stormwater runoff at its source while providing other environmental and societal benefits, including connecting pedestrians to the street. Simultaneously, human exposure to particulate matter from urban transportation is of major concern worldwide due to the proximity of pedestrians, drivers, and cyclists to the emission sources. Vegetation used for stormwater treatment can help designers limit the exposure of people to air pollutants. This goal can be achieved through the deliberate placement of green streets, along with strategic planting schemes that maximize pollutant dispersion. This communication presents general design considerations for green streets that combine stormwater management and air quality goals. There is currently limited guidance on designing green streets for air quality considerations; this is the first communication to offer suggestions and advice for the design of green stormwater streets in regards to their effects on air quality. Street characteristics including (1) the width to height ratio of the street to the buildings, (2) the type of trees and their location, and (3) any prevailing winds can have an impact on pollutant concentrations within the street and along sidewalks. Vegetation within stormwater control measures has the ability to reduce particulate matter concentrations; however, it must be carefully selected and placed within the green street to promote the dispersion of air flow. - Highlights: • Green streets can be used for both stormwater and air quality management. • Design considerations must be made to minimize human exposure to air pollutants. • Urban vegetation can improve air quality with careful selection and placement.

Swimming-induced pulmonary oedema an uncommon condition diagnosed with POCUS ultrasound.

Science.gov (United States)

Alonso, Joaquín Valle; Chowdhury, Motiur; Borakati, Raju; Gankande, Upali

2017-12-01

Swimming Induced Pulmonary Edema, or SIPE, is an emerging condition occurring in otherwise healthy individuals during surface swimming or diving that is characterized by cough, dyspnea, hemoptysis, and hypoxemia. It is typically found in those who spend time in cold water exercise with heavy swimming and surface swimming, such as civilian training for iron Man, triathalon, and military training. We report the case of a highly trained young female swimmer in excellent cardiopulmonary health, who developed acute alveolar pulmonary oedema in an open water swimming training diagnosed in the emergency department using POCUS ultrasound. Copyright © 2017 Elsevier Inc. All rights reserved.

Locomotion Dynamics for Bio-inspired Robots with Soft Appendages: Application to Flapping Flight and Passive Swimming

Science.gov (United States)

Boyer, Frédéric; Porez, Mathieu; Morsli, Ferhat; Morel, Yannick

2017-08-01

In animal locomotion, either in fish or flying insects, the use of flexible terminal organs or appendages greatly improves the performance of locomotion (thrust and lift). In this article, we propose a general unified framework for modeling and simulating the (bio-inspired) locomotion of robots using soft organs. The proposed approach is based on the model of Mobile Multibody Systems (MMS). The distributed flexibilities are modeled according to two major approaches: the Floating Frame Approach (FFA) and the Geometrically Exact Approach (GEA). Encompassing these two approaches in the Newton-Euler modeling formalism of robotics, this article proposes a unique modeling framework suited to the fast numerical integration of the dynamics of a MMS in both the FFA and the GEA. This general framework is applied on two illustrative examples drawn from bio-inspired locomotion: the passive swimming in von Karman Vortex Street, and the hovering flight with flexible flapping wings.

Thermoelastoplastic Deformation of a Multilayer Ball

Science.gov (United States)

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

2017-09-01

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

Universal design characteristic on themed streets

Science.gov (United States)

Harsritanto, Bangun IR; Indriastjario; Wijayanti

2017-12-01

People around the world can access the streets to fulfil their daily activities regardless of their gender, age, and abilities. The streetscape is an urban public space which is built to facilitate the basic needs of people as social being. The themed street is an urban streetscape designed and built in detail with a theme or special purpose in an of urban development process. Universal design facilitates the full range of human diversity as physical appearance, perception, cognitive abilities, sizes, and shapes. By designing for the diversity, the specialized streets become more functional and user-friendly. The purpose of this study is to examine several design characteristics of themed streets in several countries from three different continents using universal design principles for giving proper directions to develop more user-friendly streets. Literature review and case study were used as research methods. The literature review was extracted and compiled from manuscripts, streetscape design books, and from universal design principles. Furthermore, the constructed theory were used to examine the case studies of themed streets. The findings indicated that themed streets’ character design were strongly influenced by local cultural aspect even though the basic guidelines were universal design principles; the resumed design direction can be suggested universal along with the richness of local aspects.

The Regulation of Street Foods

DEFF Research Database (Denmark)

Forkour, John Boulard; Samuelsen, Helle; Yeboah, Eric Henry

2017-01-01

the challenges and negotiating strategies of regulators of street-vended foods in Ghana and analyses the implication for their relationship with street food vendors. The paper reveals that regulators operate in a context of limited resources, leading to a general feeling of neglect. In coping, regulators adopt...

Street Papers, Work, and Begging

DEFF Research Database (Denmark)

Cockburn, Patrick Joseph

2014-01-01

Street papers are publications produced specifically for sale by the homeless and other vulnerable people in many countries around the world. Their social status is, however, often conspicuously unstable: ‘Get a job!’ has been reported as a common insult addressed to vendors, and street paper...

Heart rate variability and swimming.

Science.gov (United States)

Koenig, Julian; Jarczok, Marc N; Wasner, Mieke; Hillecke, Thomas K; Thayer, Julian F

2014-10-01

Professionals in the domain of swimming have a strong interest in implementing research methods in evaluating and improving training methods to maximize athletic performance and competitive outcome. Heart rate variability (HRV) has gained attention in research on sport and exercise to assess autonomic nervous system activity underlying physical activity and sports performance. Studies on swimming and HRV are rare. This review aims to summarize the current evidence on the application of HRV in swimming research and draws implications for future research. A systematic search of databases (PubMed via MEDLINE, PSYNDEX and Embase) according to the PRISMA statement was employed. Studies were screened for eligibility on inclusion criteria: (a) empirical investigation (HRV) in humans (non-clinical); (b) related to swimming; (c) peer-reviewed journal; and (d) English language. The search revealed 194 studies (duplicates removed), of which the abstract was screened for eligibility. Fourteen studies meeting the inclusion criteria were included in the review. Included studies broadly fell into three classes: (1) control group designs to investigate between-subject differences (i.e. swimmers vs. non-swimmers, swimmers vs. other athletes); (2) repeated measures designs on within-subject differences of interventional studies measuring HRV to address different modalities of training or recovery; and (3) other studies, on the agreement of HRV with other measures. The feasibility and possibilities of HRV within this particular field of application are well documented within the existing literature. Future studies, focusing on translational approaches that transfer current evidence in general practice (i.e. training of athletes) are needed.

Swimming of a Sea Butterfly with an Elongated Shell

Science.gov (United States)

Karakas, Ferhat; Maas, Amy E.; Murphy, David W.

2017-11-01

Sea butterflies (pteropods) are small, zooplanktonic marine snails which swim by flapping highly flexible parapodia. Previous studies show that the swimming hydrodynamics of Limacina helicina, a polar pteropod with a spiraled shell, is similar to tiny insect flight aerodynamics and that forward-backward pitching is key for lift generation. However, swimming by diverse pteropod species with different shell shapes has not been examined. We present measurements of the swimming of Cuvierina columnella, a warm water species with an elongated non-spiraled shell collected off the coast of Bermuda. With a body length of 9 mm, wing beat frequency of 4-6 Hz and swimming speed of 35 mm/s, these organisms swim at a Reynolds number of approximately 300, larger than that of L. helicina. High speed 3D kinematics acquired via two orthogonal cameras reveals that the elongated shell correlates with reduced body pitching and that the wings bend approximately 180 degrees in each direction, overlapping at the end of each half-stroke. Time resolved 2D flow measurements collected with a micro-PIV system reveal leading edge vortices present in both power and recovery strokes. Interactions between the overlapping wings and the shell also likely play a role in lift generation.

Street Pastors : on security, care and faith

NARCIS (Netherlands)

van Steden, R.

2018-01-01

This paper presents a study of Street Pastors in Cardiff, the capital city of Wales. Street Pastors are Christian volunteers who look after vulnerable people in the night-time economy. In this manner, they provide ‘securitas’ through empathy and care. The motives of Street Pastors for engaging with

Stirring by swimming bodies

International Nuclear Information System (INIS)

Thiffeault, Jean-Luc; Childress, Stephen

2010-01-01

We consider the stirring of an inviscid fluid caused by the locomotion of bodies through it. The swimmers are approximated by non-interacting cylinders or spheres moving steadily along straight lines. We find the displacement of fluid particles caused by the nearby passage of a swimmer as a function of an impact parameter. We use this to compute the effective diffusion coefficient from the random walk of a fluid particle under the influence of a distribution of swimming bodies. We compare with the results of simulations. For typical sizes, densities and swimming velocities of schools of krill, the effective diffusivity in this model is five times the thermal diffusivity. However, we estimate that viscosity increases this value by two orders of magnitude.

On the isoperimetric rigidity of extrinsic minimal balls

DEFF Research Database (Denmark)

Markvorsen, Steen; Palmer, V.

2003-01-01

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

EFFECT OF FLEXIBILITY ON THE RESULTS OF DOLPHIN SWIMMING TECHNIQUE

Directory of Open Access Journals (Sweden)

Slađana Tošić

2011-09-01

Full Text Available In order to determine the impact of flexibility on the results in swimming, we conducted a study on a sample of 50 female patients aged 11-14 years of age who are in the training process in the swimming clubs „Nis 2005“ and „Sveti Nikola“ in Nis. The study is applied to 14 measuring instruments that were divided into three groups: Measuring instruments for the assessment of flexibility (11; Measuring instruments for assessing the results of swimming (1; Measuring instruments for evaluation of morphological characteristics (2. The regression analysis determined the impact of flexibility on the results in swimming. The regression analysis didn't confirmed the assumption that there is a statistically significant effect of flexibility variables on results in swimming for female swimmers

Unstructured socialization and territorialization. A street-ethnographic take on urban youth in a medium-sized town in Denmark

DEFF Research Database (Denmark)

Gravesen, David Thore; Frostholm, Peter Hornbæk

Abstract / Journal of youth studies Conference 2015 Peter Frostholm Olesen & David Thore Gravesen Unstructured socialization and territorialization. A street-ethnographic take on urban youth in a medium-sized town in Denmark. In 2013, the municipality in Horsens, a medium-sized provincial town...... in Denmark, bestowed the city's children and young people a skater / parkour / ball-cage facility right on the city's central squares. The facility serves as a territorial meeting place for a number of conflicting groups of adolescents with different codes of behavior based on their cultural orientation...... and sense of belonging to certain districts of the city. Through positioning battles of various kinds the groups fight for space and place for their unstructured socialization processes with their peers. Officially, the municipality donated the facility to give local children and young people an opportunity...

36 CFR 3.17 - What regulations apply to swimming areas and beaches?

Science.gov (United States)

2010-07-01

... swimming areas and beaches? 3.17 Section 3.17 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR BOATING AND WATER USE ACTIVITIES § 3.17 What regulations apply to swimming areas and beaches? (a) The superintendent may designate areas as swimming areas or swimming beaches in...

On the development of inexpensive speed and position tracking system for swimming

DEFF Research Database (Denmark)

Trangbæk, Søren; Rasmussen, Cuno; Andersen, Thomas Bull

2016-01-01

A semi-automated tracking system was developed for the analysis of swimming, using cameras, an LED diode marker, and a red swim cap. Four experienced young swimmers were equipped with a marker and a swim cap and their position and speed was tracked throughout above-water and under-water swimming...

Intra- and Intersexual swim bladder dimorphisms in the plainfin midshipman fish (Porichthys notatus): Implications of swim bladder proximity to the inner ear for sound pressure detection.

Science.gov (United States)

Mohr, Robert A; Whitchurch, Elizabeth A; Anderson, Ryan D; Forlano, Paul M; Fay, Richard R; Ketten, Darlene R; Cox, Timothy C; Sisneros, Joseph A

2017-11-01

The plainfin midshipman fish, Porichthys notatus, is a nocturnal marine teleost that uses social acoustic signals for communication during the breeding season. Nesting type I males produce multiharmonic advertisement calls by contracting their swim bladder sonic muscles to attract females for courtship and spawning while subsequently attracting cuckholding type II males. Here, we report intra- and intersexual dimorphisms of the swim bladder in a vocal teleost fish and detail the swim bladder dimorphisms in the three sexual phenotypes (females, type I and II males) of plainfin midshipman fish. Micro-computerized tomography revealed that females and type II males have prominent, horn-like rostral swim bladder extensions that project toward the inner ear end organs (saccule, lagena, and utricle). The rostral swim bladder extensions were longer, and the distance between these swim bladder extensions and each inner-ear end organ type was significantly shorter in both females and type II males compared to that in type I males. Our results revealed that the normalized swim bladder length of females and type II males was longer than that in type I males while there was no difference in normalized swim bladder width among the three sexual phenotypes. We predict that these intrasexual and intersexual differences in swim bladder morphology among midshipman sexual phenotypes will afford greater sound pressure sensitivity and higher frequency detection in females and type II males and facilitate the detection and localization of conspecifics in shallow water environments, like those in which midshipman breed and nest. © 2017 Wiley Periodicals, Inc.

Swimming of Microorganisms Viewed from String and Membrane Theories

OpenAIRE

Kawamura, Masako; Sugamoto, Akio; Nojiri, Shin'ichi

1993-01-01

Swimming of microorganisms is studied from a viewpoint of extended objects (strings and membranes) swimming in the incompressible f luid of low Reynolds number. The flagellated motion is analyzed in two dimensional fluid, by using the method developed in the ciliated motion with the Joukowski transformation. Discussion is given on the conserved charges and the algebra which are associated with the area (volume)- preserving diffeomorphisms giving the swimming motion of microorganisms. It is al...

City Streets

Data.gov (United States)

Minnesota Department of Natural Resources — This data set contains roadway centerlines for city streets found on the USGS 1:24,000 mapping series. In some areas, these roadways are current through the 2000...

A self-similar magnetohydrodynamic model for ball lightnings

International Nuclear Information System (INIS)

Tsui, K. H.

2006-01-01

Ball lightning is modeled by magnetohydrodynamic (MHD) equations in two-dimensional spherical geometry with azimuthal symmetry. Dynamic evolutions in the radial direction are described by the self-similar evolution function y(t). The plasma pressure, mass density, and magnetic fields are solved in terms of the radial label η. This model gives spherical MHD plasmoids with axisymmetric force-free magnetic field, and spherically symmetric plasma pressure and mass density, which self-consistently determine the polytropic index γ. The spatially oscillating nature of the radial and meridional field structures indicate embedded regions of closed field lines. These regions are named secondary plasmoids, whereas the overall self-similar spherical structure is named the primary plasmoid. According to this model, the time evolution function allows the primary plasmoid expand outward in two modes. The corresponding ejection of the embedded secondary plasmoids results in ball lightning offering an answer as how they come into being. The first is an accelerated expanding mode. This mode appears to fit plasmoids ejected from thundercloud tops with acceleration to ionosphere seen in high altitude atmospheric observations of sprites and blue jets. It also appears to account for midair high-speed ball lightning overtaking airplanes, and ground level high-speed energetic ball lightning. The second is a decelerated expanding mode, and it appears to be compatible to slowly moving ball lightning seen near ground level. The inverse of this second mode corresponds to an accelerated inward collapse, which could bring ball lightning to an end sometimes with a cracking sound

Spatial Character Analysis of Streets as Public Spaces: The Case of Izmit Hurriyet and Cumhuriyet Street, Turkey

Science.gov (United States)

Özbayraktar, Mehtap; Pekdemir, Merve; Mırzaliyeva, Gumru

2017-10-01

The word “public” was first used to refer to the theatre audience in France in the mid-17th century. In the 18th century, it turned into the meaning of “public space incorporating a large variety of people and composed of acquaintances and strangers”. The concepts of publicity, public space, and public realm have been studied and described by many researchers in the course of time. These descriptions show the development of public space as well. In the very general sense, public spaces are areas of personal and social happiness; collective living spaces of the society; areas of expression of natural and cultural variety; and key elements providing a ground for the establishment of an identity. In the United Nations’ report on public spaces, public space is addressed under six groups: 1. The spaces we intensely used in our daily life; 2. Green open public spaces; 3. Public activity spaces which users can go in without any difficulty, are open to public, and are under protection; 4. Public sector realm (social agreements in which the people are represented, contribute to collective goods, and trust in the administrators elected); 5. City as a public space; 6. Cyberspace. As cities grow, public spaces transform and diversify. Attempts are made to meet the changing needs through types of space developed. However, the character of the existing public spaces, the distribution of open spaces and parks and their inadequacy, the destruction of public space, and the things that are required to be done stand as important issues to be addressed. One of the public spaces going through transformation are streets which we intensely use in our daily life. In general, streets are defined as roads with buildings on both sides in settlements such as provinces and districts whose boundaries are determined by neighbouring buildings. Some researchers have defined streets based on their social functions. According to them, streets are meeting spaces; spaces to deal with

Structural and dynamical properties of Yukawa balls

International Nuclear Information System (INIS)

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

2007-01-01

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

Swimming near the substrate: a simple robotic model of stingray locomotion

International Nuclear Information System (INIS)

Blevins, Erin; Lauder, George V

2013-01-01

Studies of aquatic locomotion typically assume that organisms move through unbounded fluid. However, benthic fishes swim close to the substrate and will experience significant ground effects, which will be greatest for fishes with wide spans such as benthic batoids and flatfishes. Ground effects on fixed-wing flight are well understood, but these models are insufficient to describe the dynamic interactions between substrates and undulating, oscillating fish. Live fish alter their swimming behavior in ground effect, complicating comparisons of near-ground and freestream swimming performance. In this study, a simple, stingray-inspired physical model offers insights into ground effects on undulatory swimmers, contrasting the self-propelled swimming speed, power requirements, and hydrodynamics of fins swimming with fixed kinematics near and far from a solid boundary. Contrary to findings for gliding birds and other fixed-wing fliers, ground effect does not necessarily enhance the performance of undulating fins. Under most kinematic conditions, fins do not swim faster in ground effect, power requirements increase, and the cost of transport can increase by up to 10%. The influence of ground effect varies with kinematics, suggesting that benthic fish might modulate their swimming behavior to minimize locomotor penalties and incur benefits from swimming near a substrate. (paper)

Ovarian and uterine alterations following forced swimming: An immunohistochemical study.

Science.gov (United States)

Seyed Saadat, Seyedeh Nazanin; Mohammadghasemi, Fahimeh; Ebrahimi, Hannan; Rafati Sajedi, Hanieh; Chatrnour, Gelayol

2016-10-01

Physical exercise is known to be a stressor stimulus that leads to reproductive disruption. The aim of this study was to evaluate the effect of forced swimming on the uterus and ovaries in mice. Adult mice (N=24) were divided into the following three groups: A, control; B, swimming in water (10 o C); and C, swimming in water (23 o C). Swimmers swam for 5 min daily for 5 consecutive days/ wk during 2 wks. An enzyme linked immunosorbent assay was used to determine serum estradiol, follicle stimulating hormone (FSH) and testosterone levels. Immunohistochemistry was performed to study apoptotic cells or estrogen receptor (ER) expression in uterine epithelial cells and ovaries. ANOVA was used for statistical analysis. Swimming in both groups reduced the serum FSH and estradiol levels (pForced swimming of 2 wks duration reduces the serum levels of FSH and estradiol without having effects on apoptosis in the ovaries or uteri of mice. Over a long period of time, forced swimming may have an adverse effect on fertility.

Validity and Reliability of a Medicine Ball Explosive Power Test.

Science.gov (United States)

Stockbrugger, Barry A.; Haennel, Robert G.

2001-01-01

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

The swimming polarity of multicellular magnetotactic prokaryotes can change during an isolation process employing magnets: evidence of a relation between swimming polarity and magnetic moment intensity.

Science.gov (United States)

de Melo, Roger Duarte; Acosta-Avalos, Daniel

2017-09-01

Magnetotactic microorganisms are characterized by swimming in the direction of an applied magnetic field. In nature, two types of swimming polarity have been observed: north-seeking microorganisms that swim in the same direction as the magnetic field, and south-seeking microorganisms that swim in the opposite direction. The present work studies the reversal in the swimming polarity of the multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis following an isolation process using high magnetic fields from magnets. The proportion of north- and south-seeking organisms was counted as a function of the magnetic field intensity used during the isolation of the organisms from sediment. It was observed that the proportion of north-seeking organisms increased when the magnetic field was increased. The magnetic moment for north- and south-seeking populations was estimated using the U-turn method. The average magnetic moment was higher for north- than south-seeking organisms. The results suggest that the reversal of swimming polarity must occur during the isolation process in the presence of high magnetic fields and magnetic field gradients. It is shown for the first time that the swimming polarity reversal depends on the magnetic moment intensity of multicellular magnetotactic prokaryotes, and new studies must be undertaken to understand the role of magnetic moment polarity and oxygen gradients in determination of swimming polarity.

Feeding of swimming Paramecium with fore-aft asymmetry in viscous fluid

Science.gov (United States)

Zhang, Peng; Jana, Saikat; Giarra, Matthew; Vlachos, Pavlos; Jung, Sunghwan

2013-11-01

Swimming behaviours and feeding efficiencies of Paramecium Multimicronucleatum with fore-aft asymmetric body shapes are studied experimentally and numerically. Among various possible swimming ways, ciliates typically exhibit only one preferred swimming directions in favorable conditions. Ciliates, like Paramecia, with fore-aft asymmetric shapes preferably swim towards the slender anterior while feeding fluid to the oral groove located at the center of the body. Since both feeding and swimming efficiencies are influenced by fluid motions around the body, it is important to reveal the fluid mechanics around a moving object. Experimentally, μ-PIV methods are employed to characterize the source-dipole streamline patterns and fluid motions around Paramecium. Numerical simulations by boundary element methods are also used to evaluate surface stresses and velocities, which give insights into the efficiencies of swimming and feeding depending on body asymmetry. It is concluded that a slender anterior and fat posterior increases the combined efficiency of swimming and feeding, which matches well with actual shapes of Paramecium. Discrepancies between experiments and simulations are also discussed.

Energetics of swimming of schooling fish

DEFF Research Database (Denmark)

Steffensen, John Fleng

2012-01-01

, i.e. nearest neighbour distance, water temperature, gill oxygen extraction, gill ventilation capacity, etc. Fish swimming in a school have been shown to have energetic advantages when trailing behind neighbours, resulting in up to 20% energy saving. The effect of this energy saving is that the fish......Soc for experimental Biol Annual Meeting - Salzburg 2012 John F. Steffensen (University of Copenhagen, Denmark) When a fish school swims through the water, every individual consumes a certain amount of oxygen, which means that less will be available for the trailing fish in the school. In 1967 Mc......Farland and Moss reported that the oxygen saturation decreased approximately 30% from the front to the rear of an approximately 150-m long school of mullets swimming in normoxic water. They also observed that the decline in oxygen saturation at the rear resulted in the school disintegrating into smaller separate...

Gas-discharge particle detector with ball-tipped anodes

International Nuclear Information System (INIS)

Travkin, V.I.; Khazins, D.M.

1987-01-01

A new gas-discharge particle detector, whose anode is a set of balls 2mm in diameter is investigated. The chamber is blowing down by the argon-methane-methylal gas mixture with the ratio 3:1:1. The detector operates in the self-quenching streamer mode, has high efficiency and a wide counting characteristic plateau. The maximum counting rate of particles at one ball is ∼ 2.5x10 4 s -1 . The ball-tipped anodes allow making reliable complex-shaped detectors. Two-coordinate detection of multiparticle events can be naturally organized in detectors like that

PLC based Smart Street Lighting Control

OpenAIRE

D.V.Pushpa Latha; K.R.Sudha; Swati Devabhaktuni

2013-01-01

Conventional street lighting systems in most of the areas are Online at regular intervals of time irrespective of the seasonal variations. The street lights are simply switched on at afternoon and turned off in the morning. The consequence is that a large amount of Power is wasted meaninglessly. As energy consumption is an issue of increasing interest, possible energy savings in public street lighting systems are recently discussed from different viewpoints. The purpose of this work is to des...

Biomechanical aspects of peak performance in human swimming

NARCIS (Netherlands)

Toussaint, H.M.; Truijens, M.J.

2005-01-01

Peak performances in sport require the full deployment of all the powers an athlete possesses. How factors such as mechanical power output, technique and drag, each individually, but also in concert, determine swimming performance is the subject of this enquiry. This overview of swimming

Real-time detecting and tracking ball with OpenCV and Kinect

Science.gov (United States)

Osiecki, Tomasz; Jankowski, Stanislaw

2016-09-01

This paper presents a way to detect and track ball with using the OpenCV and Kinect. Object and people recognition, tracking are more and more popular topics nowadays. Described solution makes it possible to detect ball based on the range, which is set by the user and capture information about ball position in three dimensions. It can be store in the computer and use for example to display trajectory of the ball.

Roll and Yaw of Paramecium swimming in a viscous fluid

Science.gov (United States)

Jung, Sunghwan; Jana, Saikat; Giarra, Matt; Vlachos, Pavlos

2012-11-01

Many free-swimming microorganisms like ciliates, flagellates, and invertebrates exhibit helical trajectories. In particular, the Paramecium spirally swims along its anterior direction by the beating of cilia. Due to the oblique beating stroke of cilia, the Paramecium rotates along its long axis as it swims forward. Simultaneously, this long axis turns toward the oral groove side. Combined roll and yaw motions of Paramecium result in swimming along a spiral course. Using Particle Image Velocimetry, we measure and quantify the flow field and fluid stress around Paramecium. We will discuss how the non-uniform stress distribution around the body induces this yaw motion.

Estructura temporal y gestual del kin-ball

Directory of Open Access Journals (Sweden)

Rafael Díaz Amate

2015-06-01

Full Text Available El objetivo de este estudio es analizar la estructura temporal del kin-ball y cuantificar el número de golpeos, jugadas, puntos y los tipos de contacto utilizados, en cada período y partido. Se han analizado un total de 13 partidos, correspondientes a la fase de grupos, semifinales y final del VII Campeonato de España de Kin-ball. Es un deporte caracterizado por la realización de esfuerzos interválicos de intensidad media-alta y de corta duración. Un partido de kin-ball tiene una duración media de 46 min aproximadamente, siendo el ratio tiempo de trabajo y tiempo de descanso de 1:1,51 y la duración media por punto de 12,07 s. Así, un partido de kin-ball tiene un volumen de 73 puntos con un total de 390 golpeos. Los tipos de golpeos utilizados determinan que es un deporte defensivo. Todos estos análisis ayudan a tener un mayor conocimiento de esta disciplina deportiva por parte de los entrenadores y jugadores para tener un entrenamiento más específico.

[Addictive behavior of street children: interculturation and resilience].

Science.gov (United States)

Kommegne, T; Denoux, P; Bernoussi, A; Njiengwe, E F

2014-09-01

This research belongs to a more comprehensive study on the care of street children in Cameroon. The idea is to develop an analysis of the street pathology where symptoms such as addictive behavior and drug addiction can be found. Beside HIV AIDS, addictive behaviors are the main risk factors that many professionals have to face with while dealing with the street problems today. Through an intercultural approach, we examined the practices of addictive typology, their initiatory role and their function in the integration of the street system. We also analysed their importance in the survival strategies. After an overview of theoretical controversies that feed the debate on addictions, we questioned the impact of these practices on the street career through the prism of general theory of addictions, particularly the hedonic management model. Addiction helps to resist adversity, it helps to desist and then to begin a harmonious neo development despite the horrors of the street experience. We undertook a quantitative and qualitative study on a sample of 148 street children. We proposed to 128 of them a questionnaire focused on addictive behaviors and survival strategies in the street context. We notably evaluated the street career of 24 of them, using interviews and standardized tests to assess self-esteem (Coopersmith's SEI) frustration tolerance (Rosenweig's P-F) and self-efficacy (Sherer's SE Scale) in order to measure the impact of addictive behaviors on the resilience process. We found that the street career is essentially traumatic, and that addictive behaviors involving various integration strategies are strongly linked to the interculturation process through the identity strategies and the intercultural competences. Addiction itself is not significantly related to self-esteem issues but strongly impacts on self-efficacy and the ability to tolerate frustration. They allow the street children to withstand the street adversity but are a real obstacle to their

Street ball, swim team and the sour cream machine: a cluster analysis of out of school time participation portfolios.

Science.gov (United States)

Nelson, Ingrid Ann; Gastic, Billie

2009-10-01

Adolescents spend only a fraction of their waking hours in school and what they do with the rest of their time varies dramatically. Despite this, research on out-of-school time has largely focused on structured programming. The authors analyzed data from the Educational Longitudinal Study of 2002 (ELS:2002) to examine the out-of-school time activity portfolios of 6,338 high school sophomores, accounting for time spent in school clubs and sports as well as 17 other activities. The analytical sample was balanced with respect to sex and racially and ethnically diverse: 49% female, 67% White, 10% Latino, 10% African American, and 6% Asian and Pacific Islander. Approximately 76% of the sample attended public schools, 30% were in the highest socioeconomic quartile, and 20% were in the lowest socioeconomic quartile. The authors identified five distinct out-of-school time activity portfolios based on a cluster analysis. The demographic profiles of students by portfolio type differed significantly with respect to sex, race/ethnicity, socioeconomic status, school type and location. Students by portfolio type also differed significantly in terms of measures of academic success, school behavior, victimization and perceptions of school climate, controlling for covariates. These findings underscore the importance of more complex considerations of adolescents' out-of-school time.

The swimming program effects on the gross motor function, mental adjustment to the aquatic environment, and swimming skills in children with cerebral palsy: A pilot study

Directory of Open Access Journals (Sweden)

Jorgić Bojan

2012-01-01

Full Text Available The aim of this research was to determine the swimming program effects on the gross motor function, mental adjustment to the aquatic environment and the ability to move in the water and swim in children with cerebral palsy. The sample consisted of seven children (4 boys and 3 girls with spastic cerebral palsy and an average age of 9y 5mo ± 1y 3 mo. The swimming program lasted 6 weeks, with two swimming sessions per week. Each session lasted 45 minutes. The swimming program included the application of the Halliwick Method and swimming exercises which are used in a healthy population. The GMFM test was used for the assessment of gross motor functions. The WOTA2 test was applied to assess mental adjustment and swimming skills. The Wilcoxon matched pairs test was used to determine the statistically significant differences between the initial and final measuring. The results have indicated that there was statistically significant differences in the E dimension (p=0.04 and the total score T (p=0.03 of the GMFM test, then for mental adjustment to the aquatic environment WMA (p=0.02, ability to move in water andswimming skills WSW (p=0.03 and the overall result WTO (p=0.02 of the WOTA2 test. The applied swimming program had a statistically significant effect on the improvement in walking, running and jumping as well as the overall gross motor functions of children with cerebral palsy. The applied program also contributed to a statistically significant influence on the increase in mental adjustment to the aquatic environment and the ability to move in water and swim.

The economics of age-group swimming in Ontario.

Science.gov (United States)

Eynon, R B; Kitchen, P D; Semotiuk, D M

1980-09-01

This study investigated the socio-economic status of the parents of Ontario swimmers and parental expenditures, in terms of time and money, in support of competitive swimming. Questionnaires were mailed to a sample of 400 families of Ontario competitive swimmers. Spearman rho analyses were used to determine the relationships of membership fee, total cost and total time spent by the parents to the ability and age of the swimmer and the number of hours of practice and swim meets. Parents of Ontario competitive swimmers are upper middle class and devote a great deal of their time (X = 433 hours) and money (X = $744.00) annually to competitive swimming. Total expenditures and time spend by the parents were greater for those children were young and also for those whose children demonstrated greater ability (i.e., closer to Ontario record). Spearman rho analyses suggested that membership fees are not determined on the basis of age, number of practice hours or number of swim meets.

The street school Srikandi as an empowerment model of humane education for the street girls of non halfway house in Surabaya

Science.gov (United States)

Setyowati, RRN; Yani, MT; Imron, A.

2018-01-01

The street children have not had a solid emotional mental, however they must deal into the life of street that harsh, competitive and tend to affect negatively for their personality development. Their where abouts on the street is not motivated by family economic factor only, but it is also influenced by the disharmony of role and function of family rules and social environment influences. The street children empowerment that had been conducted by the halfway house does not run effectively. This research was aimed to identify problems faced by the street girls, to describe the efforts to overcome the problems faced by the street girls, and also developing the empowerment model for the street girls in Surabaya who do not stay in the halfway house. This research used qualitative method. The problems are often experienced by the street girls, for instance violence. Besides, imitative behavior arises as a respond towards behavior that happened to them. The parents also play role in the process of social control. The empowerment model that is designed is the educational empowerment through revitalization of family rules. Moreover, life skills education has to be strengthened to improve the welfare standard of living.

Swimming pool special; Zwembadspecial

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-05-15

This issue includes a few articles and messages on the use of heat pump systems in swimming pools. [Dutch] Dit nummer bevat onder meer een paar artikelen over het gebruik van warmtepompsystemen in zwembaden.

Formation and stabilization of multiple ball-like flames at Earth gravity

KAUST Repository

Zhou, Zhen

2018-03-20

Near-limit low-Lewis-number premixed flame behavior is studied experimentally and numerically for flames of H–CH–air mixtures that are located in a 55 mm diameter tube and below a perforated plate in a downward mixture flow. A combustion regime diagram is experimentally identified in terms of equivalence ratio and ratio of H to CH (variation of fuel Lewis number). Planar flames, cell-like flames, distorted cap-like flames, and arrays of ball-like flames are progressively observed in the experiments as the equivalence ratio is decreased. The experimentally observed ball-like lean limit flames experience chaotic motion, which is accompanied by sporadic events of flame splitting and extinction, while the total number of simultaneously burning flamelets remains approximately the same. In separate experiments, the multiple ball-like lean limit flames are stabilized by creating a slightly non-uniform mixture flow field. The CH* chemiluminescence distributions of the lean limit flames are recorded, showing that the ball-like lean limit flame front becomes more uniform in intensity and its shape approaches a spherical one with the increase of H content in the fuel. Numerical simulations are performed for single representative flames of the array of stabilized flamelets observed in the experiments. The simulated ball-like lean limit flame is further contrasted with the single ball-like flame that forms in a narrow tube (13.5 mm inner diameter) with an iso-thermal wall. The numerical results show that the ball-like lean limit flames present in the array of ball-like flames are more affected by the buoyancy-induced recirculation zone, compared with that in the narrow tube, revealing why the shape of the ball-like flame in the array deviates more from a spherical one. All in all, the wall confinement is not crucial for the formation of ball-like flames at terrestrial gravity.

Comparison of expert and nonexpert swimmers' opinions about the value, potency, and activity of four standard swimming strokes and underwater undulatory swimming.

Science.gov (United States)

Collard, L; Oboeuf, A

2009-04-01

Underwater undulatory swimming (UUS) is often perceived to be a nonessential aspect of aquatic propulsion. Given their solid theoretical and practical training in swimming, physical education students should be capable of judging the true value of the "fifth stroke," since it appears to be the most efficient technique in high level, competitive swimming. To compare opinions and connotations associated with the stroke and the four official strokes (butterfly, backstroke, breaststroke, and crawl), 198 students (32 of whom were expert swimmers; M age = 20.6 yr., SD = 1.2), were surveyed using the semantic differential of Osgood, Suci, and Tannenbaum. Although answers of expert and nonexpert swimmers differed significantly (p stroke was less attractive, less powerful, and less rapid than the four surface strokes (d = 2.88 for the expert swimmers). Putting one arm in front of the other and repeating the sequence still remains the most solidly held representation of "the right way" to swim. However, the high observed standard deviations for the underwater undulatory stimulus (SD > or = 1.1 with SD max = 3 for the expert swimmers) attests to the view being less strongly held by swimming specialists.

Anti-collapse mechanism of CBM fuzzy-ball drilling fluid

Directory of Open Access Journals (Sweden)

Lihui Zheng

2016-03-01

Full Text Available Although fuzzy-ball drilling fluid has been successfully applied in CBM well drilling, it is necessary to study its anti-collapse mechanism so that adjustable coalbed sealing effects, controllable sealing strength, rational sealing cost and controllable reservoir damage degree can be realized. In this paper, laboratory measurement was performed on the uniaxial compressive strength of the plungers of No. 3 coalbed in the Qinshui Basin and the inlet pressure of Ø38 mm coal plunger displacement. The strengths of coal plungers were tested and compared after 2% potassium chloride solution, low-solids polymer drilling fluid and fuzzy-ball drilling fluid were injected into the coal plungers respectively. It is shown that coal strength rises by 38.46% after the fuzzy-ball drilling fluid is injected (in three groups; and that no fuzzy-ball drilling fluid is lost at the displacement pressures of 20.73 and 21.46 MPa, nor 2% potassium chloride solution is leaked at such pressures of 24.79 and 25.64 MPa after the plunger was sealed by the fuzzy-ball drilling fluid. This indicates that the fuzzy-ball drilling fluid can increase the formation resistance to fluid. Indoor microscopic observation was conducted on the sealing process of the fuzzy-ball drilling fluid in sand packs with coal cuttings of three grain sizes (60–80, 80–100 and 100–120 mesh. It is shown that the leakage pathways of different sizes are sealed by the vesicles in the form of accumulation, stretch and blockage. And there are vesicles at the inlet ends of the flowing pathways in the shape of beaded blanket. The impact force of drilling tools on the sidewalls is absorbed by the vesicles due to their elasticity and tenacity, so the sidewall instability caused by drilling tools is relieved. It is concluded that the main anti-collapse mechanisms of the CBM fuzzy-ball drilling fluid are to raise the coal strength, increase the formation resistance to fluid, and buffer the impact of

Long-Term Effects on Graphene Supercapacitors of Using a Zirconia Bowl and Zirconia Balls for Ball-Mill mixing of Active Materials

Science.gov (United States)

Song, Dae-Hoon; Kim, Jin-Young; Kahng, Yung Ho; Cho, Hoonsung; Kim, Eung-Sam

2018-04-01

Improving the energy storage performance of supercapacitor electrodes based on reduced graphene oxide (RGO) is one of the main subjects in this research field. However, when a zirconia bowl and zirconia balls were used for ball-mill mixing of the active materials for RGO supercapacitors, the energy storage performance deteriorated over time. Our study revealed that the source of the problem was the inclusion of zirconia bits from abrasion of the bowl and the balls during the ballmill mixing, which increased during a period of 1 year. We probed two solutions to this problem: 1) hydrofluoric (HF) acid treatment of the RGO supercapacitors and 2) use of a tempered steel bowl and tempered steel balls for the mixing. For both cases, the energy storage performance was restored to near the initial level, showing a specific capacitance ( C sp ) of 200 F/g. Our results should lead to progress in research on RGO supercapacitors.

Cetacean Swimming with Prosthetic Limbs

Science.gov (United States)

Bode-Oke, Ayodeji; Ren, Yan; Dong, Haibo; Fish, Frank

2016-11-01

During entanglement in fishing gear, dolphins can suffer abrasions and amputations of flukes and fins. As a result, if the dolphin survives the ordeal, swimming performance is altered. Current rehabilitation technques is the use of prosthesis to regain swimming ability. In this work, analyses are focused on two dolphins with locomotive impairment; Winter (currently living in Clearwater Marine Aquarium in Florida) and Fuji (lived in Okinawa Churaumi Aquarium in Japan). Fuji lost about 75% of its fluke surface to necrosis (death of cells) and Winter lost its tail due to amputation. Both dolphins are aided by prosthetic tails that mimic the shape of a real dolphin tail. Using 3D surface reconstruction techniques and a high fidelity Computational Fluid Dynamics (CFD) flow solver, we were able to elucidate the kinematics and hydrodynamics and fluke deformation of these swimmers to clarify the effectiveness of prostheses in helping the dolphins regain their swimming ability. Associated with the performance, we identified distinct features in the wake structures that can explain this gap in the performance compared to a healthy dolphin. This work was supported by ONR MURI Grant Number N00014-14-1-0533.

Sex differences associated with intermittent swim stress.

Science.gov (United States)

Warner, Timothy A; Libman, Matthew K; Wooten, Katherine L; Drugan, Robert C

2013-11-01

Various animal models of depression have been used to seek a greater understanding of stress-related disorders. However, there is still a great need for novel research in this area, as many individuals suffering from depression are resistant to current treatment methods. Women have a higher rate of depression, highlighting the need to investigate mechanisms of sex differences. Therefore, we employed a new animal model to assess symptoms of depression, known as intermittent swim stress (ISS). In this model, the animal experiences 100 trials of cold water swim stress. ISS has already been shown to cause signs of behavioral depression in males, but has yet to be assessed in females. Following ISS exposure, we looked at sex differences in the Morris water maze and forced swim test. The results indicated a spatial learning effect only in the hidden platform task between male and female controls, and stressed and control males. A consistent spatial memory effect was only seen for males exposed to ISS. In the forced swim test, both sexes exposed to ISS exhibited greater immobility, and the same males and females also showed attenuated climbing and swimming, respectively. The sex differences could be due to different neural substrates for males and females. The goal of this study was to provide the first behavioral examination of sex differences following ISS exposure, so the stage of estrous cycle was not assessed for the females. This is a necessary future direction for subsequent experiments. The current article highlights the importance of sex differences in response to stress.

The Education Rights of Street-Involved Children

Directory of Open Access Journals (Sweden)

Sonja Grover

2010-05-01

Full Text Available This paper provides an overview of certain key aspects of the practical and legal situation of street-involved children globally. The inadequate protection of these children under both domestic and international law is addressed. The diversity of the population of street-involved children is considered as is the fact that this group is composed of both legally stateless and de facto stateless children. The relationship of street involvement to child labor, various health risks and victimization is discussed. The educational needs of older street-involved children are addressed including their right to participate in decision-making regarding aspects of educational service design and delivery. The overall objective of this paper is to encourage those who are involved in, or could impact upon educational policy to include street-involved children in their educational planning implementation and advocacy efforts.

Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

Directory of Open Access Journals (Sweden)

Yang Shicai

2016-01-01

Full Text Available AISI 316 austenitic stainless steel balls (diameters 5.0 and 12.0 mm, typical hardness 250 HV0.3 and flat samples (20×20×2.0 mm were nitrided by a pulsed glow discharge Ar/N2 plasma. Hardness of the ball surfaces was analysed using Vickers indentation. Thermal stability of the nitrided balls (diameter 12.0 mm was studied using a furnace to heat them in air for 8 hours at temperatures up to 700.0°C and then, after cooling to room temperature, the surface hardness of the heated balls was re-measured. Scanning electron microscopy and X-ray diffraction were used to study the microstructures, composition and phase formation of the nitrided sublayers. Unlubricated pin-on-disc wear testing was used to evaluate the wear resistance of nitrided stainless steel balls (5.0 mm diameter and the results were compared with similar testing on hardened Cr-Steel balls (5 mm diameter with hardness of about 650 HV0.3. All the test results indicated that the nitrided AISI 316 austenitic stainless steel balls have advantages over the hardened Cr-Steel balls in terms of retaining high hardness after heat treatment and high resistance to sliding wear at room temperature under higher counterpart stress. These properties are expected to be beneficial for wide range of bearing applications.

London 2012 Paralympic swimming: passive drag and the classification system.

Science.gov (United States)

Oh, Yim-Taek; Burkett, Brendan; Osborough, Conor; Formosa, Danielle; Payton, Carl

2013-09-01

The key difference between the Olympic and Paralympic Games is the use of classification systems within Paralympic sports to provide a fair competition for athletes with a range of physical disabilities. In 2009, the International Paralympic Committee mandated the development of new, evidence-based classification systems. This study aims to assess objectively the swimming classification system by determining the relationship between passive drag and level of swimming-specific impairment, as defined by the current swimming class. Data were collected on participants at the London 2012 Paralympic Games. The passive drag force of 113 swimmers (classes 3-14) was measured using an electro-mechanical towing device and load cell. Swimmers were towed on the surface of a swimming pool at 1.5 m/s while holding their most streamlined position. Passive drag ranged from 24.9 to 82.8 N; the normalised drag (drag/mass) ranged from 0.45 to 1.86 N/kg. Significant negative associations were found between drag and the swimming class (τ = -0.41, p < 0.01) and normalised drag and the swimming class (τ = -0.60, p < 0.01). The mean difference in drag between adjacent classes was inconsistent, ranging from 0 N (6 vs 7) to 11.9 N (5 vs 6). Reciprocal Ponderal Index (a measure of slenderness) correlated moderately with normalised drag (r(P) = -0.40, p < 0.01). Although swimmers with the lowest swimming class experienced the highest passive drag and vice versa, the inconsistent difference in mean passive drag between adjacent classes indicates that the current classification system does not always differentiate clearly between swimming groups.

Measuring Ucrit and endurance: equipment choice influences estimates of fish swimming performance.

Science.gov (United States)

Kern, P; Cramp, R L; Gordos, M A; Watson, J R; Franklin, C E

2018-01-01

This study compared the critical swimming speed (U crit ) and endurance performance of three Australian freshwater fish species in different swim-test apparatus. Estimates of U crit measured in a large recirculating flume were greater for all species compared with estimates from a smaller model of the same recirculating flume. Large differences were also observed for estimates of endurance swimming performance between these recirculating flumes and a free-surface swim tunnel. Differences in estimates of performance may be attributable to variation in flow conditions within different types of swim chambers. Variation in estimates of swimming performance between different types of flumes complicates the application of laboratory-based measures to the design of fish passage infrastructure. © 2017 The Fisheries Society of the British Isles.

Modelling traffic pollution in streets

Energy Technology Data Exchange (ETDEWEB)

Berkowicz, R.; Hertel, O. [National Environmental Research Inst., Dept. of Atmospheric Environment, Roskilde (Denmark); Larsen, S.E.; Soerensen, N.N.; Nielsen, M. [Risoe National Lab., Dept. of Meteorology and Wind Energy, Roskilde (Denmark)

1997-01-01

This report concerns mainly the subject related to modelling air pollution from traffic in urban streets. A short overview is presented over the theoretical aspects and examples of most commonly used methods and models are given. Flow and dispersion conditions in street canyons are discussed and the presentation is substantiated with the analysis of the experimental data. The main emphasis is on the modelling methods that are suitable for routine applications and a more detailed presentation is given of the Operational Street Pollution Model (OSPM), which was developed by the National Environmental Research Institute. The model is used for surveillance of air pollution from traffic in Danish cities and also for special air pollution studies. (au) 76 refs.

Smart street lighting : The advantages of LED street lighting and a smart control system in Uppsala municipality

OpenAIRE

Sjöberg, Inga; Gidén Hember, Amanda; Wallerström, Carolina

2017-01-01

The purpose of this bachelor thesis is to examine how LED street lights and a smart street light control system can reduce the energy consumption, costs and in extension the CO2 equivalents in a geographically delimited area. In 2015 the municipality of Sala installed LED armatures connected to a smart control system in the whole municipality. The smart control system enables for instance adjustment of the light intensity at specific times during the day and a supervision of the street light ...

Mechanics of undulatory swimming in a frictional fluid.

Science.gov (United States)

Ding, Yang; Sharpe, Sarah S; Masse, Andrew; Goldman, Daniel I

2012-01-01

The sandfish lizard (Scincus scincus) swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. In previous work we predicted average swimming speed by developing a numerical simulation that incorporated experimentally measured biological kinematics into a multibody sandfish model. The model was coupled to an experimentally validated soft sphere discrete element method simulation of the granular medium. In this paper, we use the simulation to study the detailed mechanics of undulatory swimming in a "granular frictional fluid" and compare the predictions to our previously developed resistive force theory (RFT) which models sand-swimming using empirically determined granular drag laws. The simulation reveals that the forward speed of the center of mass (CoM) oscillates about its average speed in antiphase with head drag. The coupling between overall body motion and body deformation results in a non-trivial pattern in the magnitude of lateral displacement of the segments along the body. The actuator torque and segment power are maximal near the center of the body and decrease to zero toward the head and the tail. Approximately 30% of the net swimming power is dissipated in head drag. The power consumption is proportional to the frequency in the biologically relevant range, which confirms that frictional forces dominate during sand-swimming by the sandfish. Comparison of the segmental forces measured in simulation with the force on a laterally oscillating rod reveals that a granular hysteresis effect causes the overestimation of the body thrust forces in the RFT. Our models provide detailed testable predictions for biological locomotion in a granular environment.

Wear numbers for ball cup and journal bearings

NARCIS (Netherlands)

Ligterink, D.J.; Moes, H.

1980-01-01

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

Two balls and a string: from ordered motion to chaos

International Nuclear Information System (INIS)

Sacks, William; Mauger, Alain

2013-01-01

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

Is swimming during pregnancy a safe exercise?

DEFF Research Database (Denmark)

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

2010-01-01

,486 singleton pregnancies. Recruitment to The Danish National Birth Cohort took place 1996-2002. Using Cox, linear and logistic regression analyses, depending on the outcome, we compared swimmers with physically inactive pregnant women; to separate a possible swimming effect from an effect of exercise......BACKGROUND: Exercise in pregnancy is recommended in many countries, and swimming is considered by many to be an ideal activity for pregnant women. Disinfection by-products in swimming pool water may, however, be associated with adverse effects on various reproductive outcomes. We examined......, bicyclists were included as an additional comparison group. RESULTS: Risk estimates were similar for swimmers and bicyclists, including those who swam throughout pregnancy and those who swam more than 1.5 hours per week. Compared with nonexercisers, women who swam in early/mid-pregnancy had a slightly...

Declines in swimming performance with age: a longitudinal study of Masters swimming champions

Directory of Open Access Journals (Sweden)

Rubin RT

2013-03-01

Full Text Available Robert T Rubin,1,2 Sonia Lin,3 Amy Curtis,4 Daniel Auerbach,5 Charlene Win6 1Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA; 2UCLA Bruin Masters Swim Club, Los Angeles, CA, USA; 3Saint Louis University School of Medicine, Saint Louis, MO, USA; 4Indiana University School of Medicine, Indianapolis, IN, USA; 5University of California, Berkeley, CA, USA; 6Loyola Marymount University, Los Angeles, CA, USA Introduction: Because of its many participants and thorough records, competitive Masters swimming offers a rich data source for determining the rate of physical decline associated with aging in physically fit individuals. The decline in performance among national champion swimmers, both men and women and in short and long swims, is linear, at about 0.6% per year up to age 70–75, after which it accelerates in quadratic fashion. These conclusions are based primarily on cross-sectional studies, and little is known about individual performance declines with aging. Herein we present performance profiles of 19 male and 26 female national and international champion Masters swimmers, ages 25 to 96 years, participating in competitions for an average of 23 years. Methods and results: Swimmers’ longitudinal data were compared with the fastest times of world record holders across ages 35–100 years by two regression methods. Neither method proved to accurately model this data set: compared with the rates of decline estimated from the world record data, which represent the best recorded times at given ages, there was bias toward shallower rates of performance decline in the longitudinal data, likely owing to a practice effect in some swimmers as they began their Masters programs. In swimmers’ later years, once maximum performance had been achieved, individual profiles followed the decline represented in the world records, and a few swimmers became the world record holders. In some instances

Behavior of hollow balls containing granules bouncing repeatedly off the ground

Science.gov (United States)

Hu, Min; Mu, Qing-song; Luo, Ning; Li, Gang; Peng, Ning-bo

2013-07-01

An experimental study of the behavior of hollow balls filled with some granules (mung beans or millets) bouncing repeatedly off a static flat horizontal surface is presented. We observed that the bounce number of the ball is limited and decreases regularly with an increasing number of granules. Moreover, for two balls containing a different kind of granules, their bounce numbers are basically equal when the two balls have the same mass of granules. While there is no clear relationship between the first rebound height of one ball and the number of granules, there appears an exponential decay of the second rebound height with an increase of the granule number. Furthermore, a two-dimensional numerical model has been created to find out the law of the ball's rebound height and the dissipation law of the granule nested system. A generalized prediction equation to reasonably explain the law of the bounce number has also been proposed.

Biochemical and Hematological Changes Following the 120-Km Open-Water Marathon Swim

Directory of Open Access Journals (Sweden)

Wojciech Drygas, Ewa Rębowska, Ewa Stępień, Jacek Golański, Magdalena Kwaśniewska

2014-09-01

Full Text Available Data on physiological effects and potential risks of a ultraendurance swimming are scarce. This report presents the unique case of a 61-year old athlete who completed a non-stop open-water 120-km ultramarathon swim on the Warta River, Poland. Pre-swimming examinations revealed favorable conditions (blood pressure, 110/70 mmHg; rest heart rate, 54 beats/minute, ejection fraction, 60%, 20.2 metabolic equivalents in a maximal exercise test. The swimming time and distance covered were 27 h 33 min and 120 km, respectively. Blood samples for hematological and biochemical parameters were collected 30 min, 4 hrs, 10 hrs and 8 days after the swim. The body temperature of the swimmer was 36.7°C before and 35.1°C after the swim. The hematological parameters remained within the reference range in the postexercise period except for leucocytes (17.5 and 10.6 x G/l noted 30 minutes and 4 hours after the swim, respectively. Serum urea, aspartate aminotransferase and C-reactive protein increased above the reference range reaching 11.3 mmol/l, 1054 nmol/l/s and 25.9 mg/l, respectively. Symptomatic hyponatremia was not observed. Although the results demonstrate that an experienced athlete is able to complete an ultra-marathon swim without negative health consequences, further studies addressing the potential risks of marathon swimming are required.

Dry grinding of talc in a stirred ball mill

Directory of Open Access Journals (Sweden)

Cayirli Serkan

2016-01-01

Full Text Available The aim of this work was to investigate micro fine size dry grindability of talc in a stirred ball mill. The effects of various parameters such as grinding time, stirrer speed, powder filling ratio and ball filling ratio were investigated. Alumina balls were used as grinding media. Experiments were carried out using the 24 full factorial design. The main and interaction effects were evaluated using the Yates method. Test results were evaluated on the basis of product size and surface area.

Ball-milling-induced crystallization and ball-milling effect on thermal crystallization kinetics in an amorphous FeMoSiB alloy

International Nuclear Information System (INIS)

Guo, F.Q.; Lu, K.

1997-01-01

Microstructure evolution in a melt-spun amorphous Fe 77.2 Mo 0.8 Si 9 B 13 alloy subjected to high-energy ball milling was investigated by means of X-ray diffraction (XRD), a transmission electron microscope (TEM), and a differential scanning calorimeter (DSC). It was found that during ball milling, crystallization occurs in the amorphous ribbon sample with precipitation of an α-Fe solid solution, and the amorphous sample crystallizes completely into a single α-Fe nanostructure (rather than α-Fe and borides as in the usual thermal crystallization products) when the milling time exceeds 135 hours. The volume fraction of material crystallized was found to be approximately proportional to the milling time. The fully crystallized sample with a single α-Fe nanophase exhibits an intrinsic thermal stability against phase separation upon annealing at high temperatures. The ball-milling effect on the subsequent thermal crystallization of the amorphous phase in an as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled partially crystallized samples. The crystallization temperatures and activation energies for the crystallization processes of the residual amorphous phase were considerably decreased due to ball milling, indicating that ball milling has a significant effect on the depression of thermal stability of the residual amorphous phase

33 CFR 117.734 - Navesink River (Swimming River).

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Navesink River (Swimming River). 117.734 Section 117.734 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1 through...

Generative Street Addresses from Satellite Imagery

Directory of Open Access Journals (Sweden)

İlke Demir

2018-03-01

Full Text Available We describe our automatic generative algorithm to create street addresses from satellite images by learning and labeling roads, regions, and address cells. Currently, 75% of the world’s roads lack adequate street addressing systems. Recent geocoding initiatives tend to convert pure latitude and longitude information into a memorable form for unknown areas. However, settlements are identified by streets, and such addressing schemes are not coherent with the road topology. Instead, we propose a generative address design that maps the globe in accordance with streets. Our algorithm starts with extracting roads from satellite imagery by utilizing deep learning. Then, it uniquely labels the regions, roads, and structures using some graph- and proximity-based algorithms. We also extend our addressing scheme to (i cover inaccessible areas following similar design principles; (ii be inclusive and flexible for changes on the ground; and (iii lead as a pioneer for a unified street-based global geodatabase. We present our results on an example of a developed city and multiple undeveloped cities. We also compare productivity on the basis of current ad hoc and new complete addresses. We conclude by contrasting our generative addresses to current industrial and open solutions.

Public Reactions to New Street Tree Planting

Directory of Open Access Journals (Sweden)

Ruth A. Rae

2010-01-01

Full Text Available MillionTreesNYC, which has the goal of planting one million trees in New York City by 2017, is intended to make New York City a greener, more sustainable city and is part of the Mayor’s comprehensive long term strategic plan, PlaNYC. Through planting a tree at every suitable sidewalk location in the city, the City of New York is transforming blocks and communities, and providing a variety of environmental, social and aesthetic benefits. This article examines the large scale municipal planting of new street trees and the reaction by some of the pubic to this planting.Trees offer benefits to the city overall, but the public may not understand these benefits or the street tree planting process. Between 2007 and 2009, the Department of Parks & Recreation planted 53,235 new street trees, and received 4,108 items of correspondence from the public. The majority of this correspondence consisted of public comments about the City’s new street tree planting policies and processes including placement objections, maintenance concerns, reports of resultant damage from tree planting operations, requests for new street trees and reports of tree conditions.This study describes the operational policies that guide New York City's municipal street tree planting, and results of content and spatial analysis of the correspondence. Qualitative analysis of the correspondence revealed the public perceptions and concerns related to the MillionTreesNYC program. Spatial analysis explored the relationship between the planting locations of new street trees and the locations of the citizen correspondence.Public reactions to this large scale municipal planting are related to the dual public and private nature of the sidewalk, issues of territoriality, responsibility, aesthetics and place attachment. Correspondence volume was associated with the scale of the new street tree block planting program, and the effectiveness of NYC’s 311 Customer Service Center. The discussion

Circular swimming in mice after exposure to a high magnetic field.

Science.gov (United States)

Houpt, Thomas A; Houpt, Charles E

2010-06-16

There is increasing evidence that exposure to high magnetic fields of 4T and above perturbs the vestibular system of rodents and humans. Performance in a swim test is a sensitive test of vestibular function. In order to determine the effect of magnet field exposure on swimming in mice, mice were exposed for 30 min within a 14.1T superconducting magnet and then tested at different times after exposure in a 2-min swim test. As previously observed in open field tests, mice swam in tight counter-clockwise circles when tested immediately after magnet exposure. The counter-clockwise orientation persisted throughout the 2-min swim test. The tendency to circle was transient, because no significant circling was observed when mice were tested at 3 min or later after magnet exposure. However, mice did show a decrease in total distance swum when tested between 3 and 40 min after magnet exposure. The decrease in swimming distance was accompanied by a pronounced postural change involving a counter-clockwise twist of the pelvis and hindlimbs that was particularly severe in the first 15s of the swim test. Finally, no persistent difference from sham-exposed mice was seen in the swimming of magnet-exposed mice when tested 60 min, 24h, or 96 h after magnet exposure. This suggests that there is no long-lasting effect of magnet exposure on the ability of mice to orient or swim. The transient deficits in swimming and posture seen shortly after magnet exposure are consistent with an acute perturbation of the vestibular system by the high magnetic field. (c) 2010 Elsevier Inc. All rights reserved.

The Physiology and Mechanics of Undulatory Swimming: A Student Laboratory Exercise Using Medicinal Leeches

Science.gov (United States)

Ellerby, David J.

2009-01-01

The medicinal leech is a useful animal model for investigating undulatory swimming in the classroom. Unlike many swimming organisms, its swimming performance can be quantified without specialized equipment. A large blood meal alters swimming behavior in a way that can be used to generate a discussion of the hydrodynamics of swimming, muscle…

Repeated swim stress alters brain benzodiazepine receptors measured in vivo

International Nuclear Information System (INIS)

Weizman, R.; Weizman, A.; Kook, K.A.; Vocci, F.; Deutsch, S.I.; Paul, S.M.

1989-01-01

The effects of repeated swim stress on brain benzodiazepine receptors were examined in the mouse using both an in vivo and in vitro binding method. Specific in vivo binding of [ 3 H]Ro15-1788 to benzodiazepine receptors was decreased in the hippocampus, cerebral cortex, hypothalamus, midbrain and striatum after repeated swim stress (7 consecutive days of daily swim stress) when compared to nonstressed mice. In vivo benzodiazepine receptor binding was unaltered after repeated swim stress in the cerebellum and pons medulla. The stress-induced reduction in in vivo benzodiazepine receptor binding did not appear to be due to altered cerebral blood flow or to an alteration in benzodiazepine metabolism or biodistribution because there was no difference in [14C]iodoantipyrine distribution or whole brain concentrations of clonazepam after repeated swim stress. Saturation binding experiments revealed a change in both apparent maximal binding capacity and affinity after repeated swim stress. Moreover, a reduction in clonazepam's anticonvulsant potency was also observed after repeated swim stress [an increase in the ED50 dose for protection against pentylenetetrazol-induced seizures], although there was no difference in pentylenetetrazol-induced seizure threshold between the two groups. In contrast to the results obtained in vivo, no change in benzodiazepine receptor binding kinetics was observed using the in vitro binding method. These data suggest that environmental stress can alter the binding parameters of the benzodiazepine receptor and that the in vivo and in vitro binding methods can yield substantially different results

Repeated swim stress alters brain benzodiazepine receptors measured in vivo

Energy Technology Data Exchange (ETDEWEB)

Weizman, R.; Weizman, A.; Kook, K.A.; Vocci, F.; Deutsch, S.I.; Paul, S.M.

1989-06-01

The effects of repeated swim stress on brain benzodiazepine receptors were examined in the mouse using both an in vivo and in vitro binding method. Specific in vivo binding of (/sup 3/H)Ro15-1788 to benzodiazepine receptors was decreased in the hippocampus, cerebral cortex, hypothalamus, midbrain and striatum after repeated swim stress (7 consecutive days of daily swim stress) when compared to nonstressed mice. In vivo benzodiazepine receptor binding was unaltered after repeated swim stress in the cerebellum and pons medulla. The stress-induced reduction in in vivo benzodiazepine receptor binding did not appear to be due to altered cerebral blood flow or to an alteration in benzodiazepine metabolism or biodistribution because there was no difference in (14C)iodoantipyrine distribution or whole brain concentrations of clonazepam after repeated swim stress. Saturation binding experiments revealed a change in both apparent maximal binding capacity and affinity after repeated swim stress. Moreover, a reduction in clonazepam's anticonvulsant potency was also observed after repeated swim stress (an increase in the ED50 dose for protection against pentylenetetrazol-induced seizures), although there was no difference in pentylenetetrazol-induced seizure threshold between the two groups. In contrast to the results obtained in vivo, no change in benzodiazepine receptor binding kinetics was observed using the in vitro binding method. These data suggest that environmental stress can alter the binding parameters of the benzodiazepine receptor and that the in vivo and in vitro binding methods can yield substantially different results.

Determination of the boundary conditions of the grinding load in ball mills

Science.gov (United States)

Sharapov, Rashid R.

2018-02-01

The prospects of application in ball mills for grinding cement clinker with inclined partitions are shown. It is noted that ball mills with inclined partitions are more effective. An algorithm is proposed for calculating the power consumed by a ball mill with inclined inter-chamber partitions in which an axial movement of the ball load takes place. The boundary conditions in which the ball load is located are determined. The equations of bounding the grinding load are determined. The behavior of a grinding load is considered in view of the characteristic cross sections. The coordinates of the centers of gravity of the grinding load with a definite step and the shape of the cross sections are determined. It is theoretically shown that grinding load in some parts of the ball mill not only consumes, but also helps to rotate the ball mill. Methods for calculating complex analytical expressions for determining the coordinates of the centers of gravity of the grinding load under the conditions of its longitudinal motion have developed. The carried out researches allow to approach from the general positions to research of behavior of a grinding load in the ball mills equipped with various in-mill devices.

On the swimming motion of spheroidal magnetotactic bacteria

Energy Technology Data Exchange (ETDEWEB)

Cui Zhen; Kong Dali; Zhang Keke [Department of Mathematical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Pan Yongxin, E-mail: kzhang@ex.ac.uk [Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing (China)

2012-10-15

We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

On the swimming motion of spheroidal magnetotactic bacteria

International Nuclear Information System (INIS)

Cui Zhen; Kong Dali; Zhang Keke; Pan Yongxin

2012-01-01

We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

Passive control potentials of trees and on-street parked cars in reduction of air pollution exposure in urban street canyons

International Nuclear Information System (INIS)

Abhijith, K.V.; Gokhale, Sharad

2015-01-01

This study investigates the passive-control-potentials of trees and on-street parked cars on pedestrian exposure to air pollutants in a street canyon using three-dimensional CFD. Since, according to some studies trees deteriorate air quality and cars parked roadside improve it, the combine as well as separate effects of trees and on-street parked cars have been examined. For this, different tree canopy layouts and parking configurations have been developed and pedestrian exposure for each has been analysed. The results showed, for example, tree crown with high porosity and low-stand density in combination with parallel or perpendicular car parking reduced the pedestrian exposure considerably. - Highlights: • Trees and on-street parked cars can manipulate pollutant levels in street canyons. • Low stand density trees with 0° or 90° car parking reduce pedestrian exposure. • Trees with medium crown, high porosity, low stand density reduce pollutant levels. - This study investigated the combination of trees and on-street parked cars to manipulate pollutant levels in urban street canyons to reduce pedestrian exposure

Water Penetration into Middle Ear Through Ventilation Tubes in Children While Swimming

Directory of Open Access Journals (Sweden)

Mao-Che Wang

2009-02-01

Conclusion: Water penetration into the middle ear through ventilation tubes and middle ear infection are not likely when surface swimming. Children with ventilation tubes can enjoy swimming without protection in clean chlorinated swimming pools.

Thermal Analysis of Ball screw Systems by Explicit Finite Difference Method

Energy Technology Data Exchange (ETDEWEB)

Min, Bog Ki [Hanyang Univ., Seoul (Korea, Republic of); Park, Chun Hong; Chung, Sung Chong [KIMM, Daejeon (Korea, Republic of)

2016-01-15

Friction generated from balls and grooves incurs temperature rise in the ball screw system. Thermal deformation due to the heat degrades positioning accuracy of the feed drive system. To compensate for the thermal error, accurate prediction of the temperature distribution is required first. In this paper, to predict the temperature distribution according to the rotational speed, solid and hollow cylinders are applied for analysis of the ball screw shaft and nut, respectively. Boundary conditions such as the convective heat transfer coefficient, friction torque, and thermal contact conductance (TCC) between balls and grooves are formulated according to operating and fabrication conditions of the ball screw. Explicit FDM (finite difference method) is studied for development of a temperature prediction simulator. Its effectiveness is verified through numerical analysis.

The goalkeeper influence on ball possession effectiveness in futsal

Directory of Open Access Journals (Sweden)

Vicente-Vila Pedro

2016-06-01

Full Text Available The aim of this study was to identify which variables were the best predictors of success in futsal ball possession when controlling for space and task related indicators, situational variables and the participation of the goalkeeper as a regular field player or not (5 vs. 4 or 4 vs. 4. The sample consisted of 326 situations of ball possession corresponding to 31 matches played by a team from the Spanish Futsal League during the 2010–2011, 2011–2012 and 2012–2013 seasons. Multidimensional qualitative data obtained from 10 ordered categorical variables were used. Data were analysed using chi-square analysis and multiple logistic regression analysis. Overall, the highest ball possession effectiveness was achieved when the goalkeeper participated as a regular field player (p<0.01, the duration of the ball possession was less than 10 s (p<0.01, the ball possession ended in the penalty area (p<0.01 and the defensive pressure was low (p<0.01. The information obtained on the relative effectiveness of offensive playing tactics can be used to improve team’s goal-scoring and goal preventing abilities.

An investigation of the generation and properties of laboratory-produced ball lightning

Science.gov (United States)

Oreshko, A. G.

2015-06-01

The experiments revealed that ball lightning is a self-confining quasi-neutral in a whole plasma system that rotates around its axis. Ball lightning has a structure of a spherical electric domain, consisting of a kernel with excess negative charge and an external spherical layer with excess positive charge. The excess of charges of one sort and the lack of charges of the other sort in the kernel or in the external spherical layer significantly reduces the possibility of electron capture by means of an electric field, created by the nearest ions and leads to a drastic slowdown of recombination process. Direct proof has been obtained that inside of ball lightning - in an external spherical layer that rotates around the axis - there is a circular current of sub-relativistic particles. This current creates and maintains its own poloidal magnetic field of ball lightning, i.e. it carries out the function of magnetic dynamo. The kernel of ball lightning is situated in a region with minimum values of induction of the magnetic field. The inequality of positive and negative charges in elements of ball lightning also significantly reduces losses of the charged plasma on bremsstrahlung. Ball lightning generation occurs in a plasmic vortex. The ball lightning energy in the region of its generation significantly differs from the ball lightning energy, which is drifting in space. The axial component of kinetic energy of particles slightly exceeds 100 keV and the rotational component of the ions energy is a bit greater than 1 MeV. Ball lightning is `embedded' in atmosphere autonomous accelerator of charged particles of a cyclotron type due to self-generation of strong crossed electric and magnetic fields. A discussion of the conditions of stability and long-term existence of ball lightning is given.

Solar collectors for swimming pools still going strong

Energy Technology Data Exchange (ETDEWEB)

1975-01-01

According to the opinion of the experts, solar energy heating may be technically 'mature' but the profitability is by no means that far. However, solar systems are a good alternative for heating the water in swimming pools. Four solar collector systems developed by different firms to heat swimming pools, including prices, are presented.

An aerodynamic analysis of recent FIFA world cup balls

Science.gov (United States)

Kiratidis, Adrian L.; Leinweber, Derek B.

2018-05-01

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

[Street social education: historical, political and pedagogical bases].

Science.gov (United States)

de Oliveira, Walter Ferreira

2007-01-01

This work is about street social education as a pedagogical system that started in Latin America in the late 1970s, as the street population formed mostly by children and adolescents called for attention. The first street social educators were 'pastoral' agents working at the praça da Sé a place with large numbers of street children in São Paulo. Based on the Liberation Theology and on the pedagogies developed by Paulo Freire, Celestine Freinet, Anton Makarenko, and Emília Ferreiro, the street educators developed a conceptual field and participated in the promulgation of the 1988 Federal Constitution, particularly by writing and introducing the 'Estatuto da Criança e do Adolescente' (the 'Child and Adolescent Statute'). Street social education is currently latent and suffering the consequences of program discontinuity caused by successive changes of government. It is, therefore important to know the conceptual proposals.

Noncontact Cohesive Swimming of Bacteria in Two-Dimensional Liquid Films.

Science.gov (United States)

Li, Ye; Zhai, He; Sanchez, Sandra; Kearns, Daniel B; Wu, Yilin

2017-07-07

Bacterial swimming in confined two-dimensional environments is ubiquitous in nature and in clinical settings. Characterizing individual interactions between swimming bacteria in 2D confinement will help to understand diverse microbial processes, such as bacterial swarming and biofilm formation. Here we report a novel motion pattern displayed by flagellated bacteria in 2D confinement: When two nearby cells align their moving directions, they tend to engage in cohesive swimming without direct cell body contact, as a result of hydrodynamic interaction but not flagellar intertwining. We further found that cells in cohesive swimming move with higher directional persistence, which can increase the effective diffusivity of cells by ∼3 times as predicted by computational modeling. As a conserved behavior for peritrichously flagellated bacteria, cohesive swimming in 2D confinement may be key to collective motion and self-organization in bacterial swarms; it may also promote bacterial dispersal in unsaturated soils and in interstitial space during infections.

Alcohol in urban streetscapes: a comparison of the use of Google Street View and on-street observation.

Science.gov (United States)

Clews, Chris; Brajkovich-Payne, Roza; Dwight, Emily; Ahmad Fauzul, Ayob; Burton, Madeleine; Carleton, Olivia; Cook, Julie; Deroles, Charlotte; Faulkner, Ruby; Furniss, Mary; Herewini, Anahera; Huband, Daymen; Jones, Nerissa; Kim, Cho Wool; Li, Alice; Lu, Jacky; Stanley, James; Wilson, Nick; Thomson, George

2016-05-26

Alcohol-related harm is a major global health issue, and controls on alcohol marketing are one intervention utilized by governments. This study investigated the use of Google Street View (GSV) as a novel research method for collecting alcohol-related data in the urban environment. The efficacy of GSV and on-street observation by observer teams was compared by surveying 400 m stretches of 12 streets in Wellington, the capital city of New Zealand. Data on alcohol sale, alcohol-related advertising, health promotion materials, regulatory information and visible alcohol consumption were collected. A total of 403 retailers with evidence of alcohol sales and 1161 items of alcohol-related communication were identified in on-street observation. Of the latter, 1028 items (89 %) were for alcohol marketing and 133 (11 %) were for alcohol-related health promotion and alcohol regulation. GSV was found to be a less sensitive tool than on-street observation with only 50 % of the alcohol venues identified and 52 % of the venue-associated brand marketing identified. A high degree of inter-observer reliability was generally found between pairs of observers e.g., for the detection of alcohol retail venues the intra-class correlation coefficient (ICC) was 0.93 (95 % CI: 0.78 to 0.98) for on-street observation and 0.85 (95 % CI: 0.49 to 0.96) for using GSV. GSV does not seem suitable for the comprehensive study of the influences on alcohol consumption in the urban streetscape. However, it may still have value for large, static objects in the environment and be more time efficient than traditional on-street observation measures, especially when used to collect data across a wide geographical area. Furthermore, GSV might become a more useful research tool in settings with better image quality (such as more 'footpath views') and with more regularly updated GSV imagery.

Electrostatic charge bounds for ball lightning models

International Nuclear Information System (INIS)

Stephan, Karl D

2008-01-01

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

Swimming mechanics and propulsive efficiency in the chambered nautilus

Science.gov (United States)

Neil, Thomas R.; Askew, Graham N.

2018-02-01

The chambered nautilus (Nautilus pompilius) encounters severe environmental hypoxia during diurnal vertical movements in the ocean. The metabolic cost of locomotion (Cmet) and swimming performance depend on how efficiently momentum is imparted to the water and how long on-board oxygen stores last. While propulsive efficiency is generally thought to be relatively low in jet propelled animals, the low Cmet in Nautilus indicates that this is not the case. We measured the wake structure in Nautilus during jet propulsion swimming, to determine their propulsive efficiency. Animals swam with either an anterior-first or posterior-first orientation. With increasing swimming speed, whole cycle propulsive efficiency increased during posterior-first swimming but decreased during anterior-first swimming, reaching a maximum of 0.76. The highest propulsive efficiencies were achieved by using an asymmetrical contractile cycle in which the fluid ejection phase was relatively longer than the refilling phase, reducing the volume flow rate of the ejected fluid. Our results demonstrate that a relatively high whole cycle propulsive efficiency underlies the low Cmet in Nautilus, representing a strategy to reduce the metabolic demands in an animal that spends a significant part of its daily life in a hypoxic environment.

Numerical study of Q-ball formation in gravity mediation

International Nuclear Information System (INIS)

Hiramatsu, Takashi; Kawasaki, Masahiro; Takahashi, Fuminobu

2010-01-01

We study Q-ball formation in the expanding universe on 1D, 2D and 3D lattice simulations. We obtain detailed Q-ball charge distributions, and find that the distribution is peaked at Q 3D peak ≅ 1.9 × 10 −2 (|Φ in |/m) 2 , which is greater than the existing result by about 60%. Based on the numerical simulations, we discuss how the Q-ball formation proceeds. Also we make a comment on possible deviation of the charge distributions from what was conjectured in the past

Results from the crystal ball detector at SPEAR

International Nuclear Information System (INIS)

Bloom, E.D.

1979-11-01

The Crystal Ball detector is a device particularly suited to the measurement of photons with energies lower than 1 GeV. The detector has as its principal component a 16 radiation length thick, highly segmented shell of NaI(Tl) surrounding cylindrical, proportional, and magnetostrictive spark chambers. The main Ball and various elements of the central chambers cover 94% of 4π sr. Segmented endcap NaI(Tl) detectors of 20 radiation lengths behind magneto strictive spark chambers supplement the main Ball. The Ball and endcaps close the solid angle for charged particle and photon detection to 98% of 4π sr. In addition, detectors of interspersed iron and proportional tubes provide for μ-π separation over 15% of 4π sr, about theta/sub CM/ = 90 0 . In this report preliminary results are presented from the data obtained. In particular, QED at E/sub CM/ = 6.5 GeV, R/sub hadron/ and related inclusive distributions, eta branching fractions at J/psi and psi'', and a detailed study of the psionium system are discussed

Measurements of the Motion of Plasma Filaments in a Plasma Ball

International Nuclear Information System (INIS)

Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S.J.

2010-01-01

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ∼106 cm/sec at the driving frequency of ∼26 kHz, and drift upward through the ball at ∼1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

Measurements of the Motion of Plasma Filaments in a Plasma Ball

Energy Technology Data Exchange (ETDEWEB)

Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S. J.

2010-01-26

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

Supermassive dark-matter Q-balls in galactic centers?

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-11

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

Unsteady propulsion by an intermittent swimming gait

Science.gov (United States)

Akoz, Emre; Moored, Keith W.

2018-01-01

Inviscid computational results are presented on a self-propelled swimmer modeled as a virtual body combined with a two-dimensional hydrofoil pitching intermittently about its leading edge. Lighthill (1971) originally proposed that this burst-and-coast behavior can save fish energy during swimming by taking advantage of the viscous Bone-Lighthill boundary layer thinning mechanism. Here, an additional inviscid Garrick mechanism is discovered that allows swimmers to control the ratio of their added mass thrust-producing forces to their circulatory drag-inducing forces by decreasing their duty cycle, DC, of locomotion. This mechanism can save intermittent swimmers as much as 60% of the energy it takes to swim continuously at the same speed. The inviscid energy savings are shown to increase with increasing amplitude of motion, increase with decreasing Lighthill number, Li, and switch to an energetic cost above continuous swimming for sufficiently low DC. Intermittent swimmers are observed to shed four vortices per cycle that form into groups that are self-similar with the DC. In addition, previous thrust and power scaling laws of continuous self-propelled swimming are further generalized to include intermittent swimming. The key is that by averaging the thrust and power coefficients over only the bursting period then the intermittent problem can be transformed into a continuous one. Furthermore, the intermittent thrust and power scaling relations are extended to predict the mean speed and cost of transport of swimmers. By tuning a few coefficients with a handful of simulations these self-propelled relations can become predictive. In the current study, the mean speed and cost of transport are predicted to within 3% and 18% of their full-scale values by using these relations.

Wearable inertial sensors in swimming motion analysis: a systematic review.

Science.gov (United States)

de Magalhaes, Fabricio Anicio; Vannozzi, Giuseppe; Gatta, Giorgio; Fantozzi, Silvia

2015-01-01

The use of contemporary technology is widely recognised as a key tool for enhancing competitive performance in swimming. Video analysis is traditionally used by coaches to acquire reliable biomechanical data about swimming performance; however, this approach requires a huge computational effort, thus introducing a delay in providing quantitative information. Inertial and magnetic sensors, including accelerometers, gyroscopes and magnetometers, have been recently introduced to assess the biomechanics of swimming performance. Research in this field has attracted a great deal of interest in the last decade due to the gradual improvement of the performance of sensors and the decreasing cost of miniaturised wearable devices. With the aim of describing the state of the art of current developments in this area, a systematic review of the existing methods was performed using the following databases: PubMed, ISI Web of Knowledge, IEEE Xplore, Google Scholar, Scopus and Science Direct. Twenty-seven articles published in indexed journals and conference proceedings, focusing on the biomechanical analysis of swimming by means of inertial sensors were reviewed. The articles were categorised according to sensor's specification, anatomical sites where the sensors were attached, experimental design and applications for the analysis of swimming performance. Results indicate that inertial sensors are reliable tools for swimming biomechanical analyses.

Swimming of a Tiny Subtropical Sea Butterfly with Coiled Shell

Science.gov (United States)

Murphy, David; Karakas, Ferhat; Maas, Amy

2017-11-01

Sea butterflies, also known as pteropods, include a variety of small, zooplanktonic marine snails. Thecosomatous pteropods possess a shell and swim at low Reynolds numbers by beating their wing-like parapodia in a manner reminiscent of insect flight. In fact, previous studies of the pteropod Limacina helicina have shown that pteropod swimming hydrodynamics and tiny insect flight aerodynamics are dynamically similar. Studies of L. helicina swimming have been performed in polar (0 degrees C) and temperate conditions (12 degrees C). Here we present measurements of the swimming of Heliconoides inflatus, a smaller yet morphologically similar pteropod that lives in warm Bermuda seawater (21 degrees C) with a viscosity almost half that of the polar seawater. The collected H. inflatus have shell sizes less than 1.5 mm in diameter, beat their wings at frequencies up to 11 Hz, and swim upwards in sawtooth trajectories at speeds up to approximately 25 mm/s. Using three-dimensional wing and body kinematics collected with two orthogonal high speed cameras and time-resolved, 2D flow measurements collected with a micro-PIV system, we compare the effects of smaller body size and lower water viscosity on the flow physics underlying flapping-based swimming by pteropods and flight by tiny insects.

Numerical and experimental investigations of human swimming motions.

Science.gov (United States)

Takagi, Hideki; Nakashima, Motomu; Sato, Yohei; Matsuuchi, Kazuo; Sanders, Ross H

2016-08-01

This paper reviews unsteady flow conditions in human swimming and identifies the limitations and future potential of the current methods of analysing unsteady flow. The capability of computational fluid dynamics (CFD) has been extended from approaches assuming steady-state conditions to consideration of unsteady/transient conditions associated with the body motion of a swimmer. However, to predict hydrodynamic forces and the swimmer's potential speeds accurately, more robust and efficient numerical methods are necessary, coupled with validation procedures, requiring detailed experimental data reflecting local flow. Experimental data obtained by particle image velocimetry (PIV) in this area are limited, because at present observations are restricted to a two-dimensional 1.0 m(2) area, though this could be improved if the output range of the associated laser sheet increased. Simulations of human swimming are expected to improve competitive swimming, and our review has identified two important advances relating to understanding the flow conditions affecting performance in front crawl swimming: one is a mechanism for generating unsteady fluid forces, and the other is a theory relating to increased speed and efficiency.

Health risks associated with swimming at an inland river

Science.gov (United States)

Swimming exposure to fecally-contaminated oceans and lakes has been associated with an increased risk of gastrointestinal (GI) illness. Although treated and untreated sewage are often discharged to rivers, the health risks of swimming exposure on rivers has been less frequently ...

Estimating energy expenditure during front crawl swimming using accelerometers

DEFF Research Database (Denmark)

Nordsborg, Nikolai Baastrup; Espinosa, Hugo G.; Van Thiel, David H

2014-01-01

The determination of energy expenditure is of major interest in training load and performance assessment. Small, wireless accelerometer units have the potential to characterise energy expenditure during swimming. The correlation between absorbed oxygen versus flume swimming speed and absorbed oxy...

Detecting Themed Streets Using a Location Based Service Application

Directory of Open Access Journals (Sweden)

Byeongsuk Ji

2016-07-01

Full Text Available Various themed streets have recently been developed by local governments in order to stimulate local economies and to establish the identity of the corresponding places. However, the motivations behind the development of some of these themed street projects has been based on profit, without full considerations of people’s perceptions of their local areas, resulting in marginal effects on the local economies concerned. In response to this issue, this study proposed a themed street clustering method to detect the themed streets of a specific region, focusing on the commercial themed street, which is more prevalent than other types of themed streets using location based service data. This study especially uses “the street segment” as a basic unit for analysis. The Sillim and Gangnam areas of Seoul, South Korea were chosen for the evaluation of the adequacy of the proposed method. By comparing trade areas that were sourced from a market analysis report by a reliable agent with the themed streets detected in this study, the experiment results showed high proficiency of the proposed method.

Swimming behavior and prey retention of the polychaete larvae Polydora ciliata (Johnston)

DEFF Research Database (Denmark)

Hansen, B.W.; Jakobsen, Hans Henrik; Andersen, Anders Peter

2010-01-01

in specific feeding rates and the observed increase in the difference between upward and downward swimming speeds with larval size. We estimated a critical larval length above which the buoyancy-corrected weight of the larva exceeds the propulsion force generated by the ciliary swimming apparatus and thus......The behavior of the ubiquitous estuarine planktotrophic spionid polychaete larvae Polydora ciliata was studied. We describe ontogenetic changes in morphology, swimming speed and feeding rates and have developed a simple swimming model using low Reynolds number hydrodynamics. In the model we assumed...... that the ciliary swimming apparatus is primarily composed of the prototroch and secondarily by the telotroch. The model predicted swimming speeds and feeding rates that corresponded well with the measured speeds and rates. Applying empirical data to the model, we were able to explain the profound decrease...

Modelling Pollutant Dispersion in a Street Network

Science.gov (United States)

Salem, N. Ben; Garbero, V.; Salizzoni, P.; Lamaison, G.; Soulhac, L.

2015-04-01

This study constitutes a further step in the analysis of the performances of a street network model to simulate atmospheric pollutant dispersion in urban areas. The model, named SIRANE, is based on the decomposition of the urban atmosphere into two sub-domains: the urban boundary layer, whose dynamics is assumed to be well established, and the urban canopy, represented as a series of interconnected boxes. Parametric laws govern the mass exchanges between the boxes under the assumption that the pollutant dispersion within the canopy can be fully simulated by modelling three main bulk transfer phenomena: channelling along street axes, transfers at street intersections, and vertical exchange between street canyons and the overlying atmosphere. Here, we aim to evaluate the reliability of the parametrizations adopted to simulate these phenomena, by focusing on their possible dependence on the external wind direction. To this end, we test the model against concentration measurements within an idealized urban district whose geometrical layout closely matches the street network represented in SIRANE. The analysis is performed for an urban array with a fixed geometry and a varying wind incidence angle. The results show that the model provides generally good results with the reference parametrizations adopted in SIRANE and that its performances are quite robust for a wide range of the model parameters. This proves the reliability of the street network approach in simulating pollutant dispersion in densely built city districts. The results also show that the model performances may be improved by considering a dependence of the wind fluctuations at street intersections and of the vertical exchange velocity on the direction of the incident wind. This opens the way for further investigations to clarify the dependence of these parameters on wind direction and street aspect ratios.

Psychosocial profile of institutionalised street children in Alexandria ...

African Journals Online (AJOL)

Objective: The phenomenon of street children in Egypt constitutes a public health concern. This study aimed to investigate the characteristics of institutionalised street children in Alexandria, to compare the prevalence of substance abuse and conduct disorder between street children and school children, and to identify ...

Street Food Consumption and its associated socio-demographic ...

African Journals Online (AJOL)

Street Food Consumption and its associated socio-demographic factors in Oyo town, Nigeria. ... Abstract. Background: Contemporary life-styles have made street foods to be an important meal option in Nigeria. They contribute ... Nutrition education is suggested for people to make a better choice of nourishing street foods.

Structure Design and Performance Analysis of High-Speed Miniature Ball Bearing

Science.gov (United States)

Li, Songsheng; Zhang, Guoye; Chen, Bin; Shen, Yuan

2017-07-01

The working performances of miniature ball bearings are obviously affected by its’ geometric structure parameters. In this paper, quasi-static analysis theory is applied in the design of miniature ball bearings. Firstly, it is studied the influence of geometry structure, preload and rotating speed on the dynamic performance of bearing. Secondly, bearing dynamic characteristics are analyzed which include the bearing stiffness and Spin to roll Ratio. Lastly, the contact stress and bearing life are calculated. The results indicate that structure parameters play an importance role in bearing’s dynamic performances. Miniature ball bearings which have lager ball number, bigger ball diameter and smaller inner race groove radius can get better performances while velocity and preload have great impact on the bearing life. So that parameters of miniature bearing should be chosen cautiously.

Swimming black-crowned night-herons (Nycticorax nycticorax) Kleptoparasitize American coots (Fulica americana)

DEFF Research Database (Denmark)

Graves, Gary R.

2015-01-01

I observed black-crowned night-herons (Nycticorax nycticorax) swimming and kleptoparasitizing American coots (Fulica americana) at an artificial lake in Pinal County, Arizona. This appears to be the first record of interspecific kleptoparasitism by a swimming ardeid.......I observed black-crowned night-herons (Nycticorax nycticorax) swimming and kleptoparasitizing American coots (Fulica americana) at an artificial lake in Pinal County, Arizona. This appears to be the first record of interspecific kleptoparasitism by a swimming ardeid....

On the escape of pollutants from urban street canyons

Energy Technology Data Exchange (ETDEWEB)

Baik, J.J.; Kim, J.J. [Kwangju Inst. of Science and Technology (Korea). Dept. of Environmental Science and Engineering

2002-07-01

Pollutant transport from urban street canyons is numerically investigated using a two-dimensional flow and dispersion model. The ambient wind blows perpendicular to the street and passive pollutants are released at the street level. Results from the control experiment with a street aspect ratio of 1 show that at the roof level of the street canyon, the vertical turbulent flux of pollutants is upward everywhere and the vertical flux of pollutants by mean flow is upward or downward. The horizontally integrated vertical flux of pollutants by mean flow at the roof level of the street canyon is downward and its magnitude is much smaller than that by turbulent process. These results indicate that pollutants escape from the street canyon mainly by turbulent process and that the net effect of mean flow is to make some escaped pollutants reenter the street canyon. Further experiments with different inflow turbulence intensities, inflow wind speeds, and street aspect ratio confirm the findings from the control experiment. In the case of two isolated buildings, the horizontally integrated vertical flux of pollutants by mean flow is upward due to flow separation but the other main results are the same as those from the control experiment. (author)

Neural extrapolation of motion for a ball rolling down an inclined plane.

Science.gov (United States)

La Scaleia, Barbara; Lacquaniti, Francesco; Zago, Myrka

2014-01-01

It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

Neural extrapolation of motion for a ball rolling down an inclined plane.

Directory of Open Access Journals (Sweden)

Barbara La Scaleia

Full Text Available It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions and slope (30°, 45° or 60°. In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1. However, even when participants punched an imaginary moving ball (Experiment 2 or drew in air the imaginary trajectory (Experiment 3, they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

Ball lightning dynamics and stability at moderate ion densities

International Nuclear Information System (INIS)

Morrow, R

2017-01-01

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

Contribution of Visual Information about Ball Trajectory to Baseball Hitting Accuracy.

Directory of Open Access Journals (Sweden)

Takatoshi Higuchi

Full Text Available The contribution of visual information about a pitched ball to the accuracy of baseball-bat contact may vary depending on the part of trajectory seen. The purpose of the present study was to examine the relationship between hitting accuracy and the segment of the trajectory of the flying ball that can be seen by the batter. Ten college baseball field players participated in the study. The systematic error and standardized variability of ball-bat contact on the bat coordinate system and pitcher-to-catcher direction when hitting a ball launched from a pitching machine were measured with or without visual occlusion and analyzed using analysis of variance. The visual occlusion timing included occlusion from 150 milliseconds (ms after the ball release (R+150, occlusion from 150 ms before the expected arrival of the launched ball at the home plate (A-150, and a condition with no occlusion (NO. Twelve trials in each condition were performed using two ball speeds (31.9 m·s-1 and 40.3 m·s-1. Visual occlusion did not affect the mean location of ball-bat contact in the bat's long axis, short axis, and pitcher-to-catcher directions. Although the magnitude of standardized variability was significantly smaller in the bat's short axis direction than in the bat's long axis and pitcher-to-catcher directions (p < 0.001, additional visible time from the R+150 condition to the A-150 and NO conditions resulted in a further decrease in standardized variability only in the bat's short axis direction (p < 0.05. The results suggested that there is directional specificity in the magnitude of standardized variability with different visible time. The present study also confirmed the limitation to visual information is the later part of the ball trajectory for improving hitting accuracy, which is likely due to visuo-motor delay.

Schooling reduces energy consumption in swimming male European eels, Anguilla anguilla L.

NARCIS (Netherlands)

Burgerhout, E.; Tudorache, C.; Brittijn, S.A.; Palstra, A.P.; Dirks, R.P.; Thillart, G.E.E.J.M.

2013-01-01

During migration, swimming in schools provides fish with a number of behavioural and ecological advantages, including increased food supply and reduced predation risk. Previous work shows that carangiform and tunniform swimming result in energetic advantages for individuals using a diamond swimming

Social and economic characteristics of street youth by gender and level of street involvement in Eldoret, Kenya.

Directory of Open Access Journals (Sweden)

Rebecca Sorber

Full Text Available Street-connected youth are a neglected and vulnerable population, particularly in resource-constrained settings. The development of interventions and supports for this population requires insight into how they live. This study describes the social and economic characteristics of a convenience sample of street youth (SY in Eldoret, Kenya.Participants were eligible if they were aged 12-21, living in Eldoret, spending days only (part-time, or nights and days on the street (full-time and able and willing to consent or assent. Data were collected using a standardized interview conducted in English or Kiswahili. Binary dependent variables were having been arrested and/or jailed, and first priority for spending money (food vs. other. Nominal categorical dependent variables included major source of support, and major reason for being street-involved. Multivariable analysis used logistic regression models to examine the association of gender and level of street-involvement with social and economic factors of interest adjusting for age and length of time on the street. Data were analyzed using SAS 9.3.Of the 200 SY enrolled, 41% were female, mean age of 16.3 years; 71% were on the street full-time, and 29% part-time. Compared with part-time SY, full-time SY were more likely to have been arrested (Adjusted Odds Ratio [AOR]: 2.33, 95% Confidence Interval [95%CI]:1.01-5.35, name food as their first spending priority (AOR: 2.57, 95%CI:1.03-6.45, have left home due to violence (AOR: 5.54, 95%CI: 1.67-18.34, and more likely to report friends on the street as a major source of support (AOR: 3.59, 95% CI: 1.01-12.82. Compared with females, males were more likely to have ever been arrested (AOR: 2.66, 95%CI:1.14-6.18, and to have ever been jailed (AOR: 3.22, 95%CI:1.47-7.02.These results suggest a high degree of heterogeneity and vulnerability among SY in this setting. There is an urgent need for interventions taking into consideration these characteristics.

OpenStreetMap over WMS

Directory of Open Access Journals (Sweden)

Přemysl Vohnout

2010-02-01

Full Text Available This paper discuss the issues which we faced, while preparing WMS server with OpenStreetMap data of whole Europe. This article is divided into three sections. First is about mandatory applications which are required for working WMS service with OpenStreetMap data. Second is focused on tuning up PostgreSQL. Third is focused on rendering time improvement of layers.

POLE-LIKE STREET FURNITURE DECOMPOSTION IN MOBILE LASER SCANNING DATA

Directory of Open Access Journals (Sweden)

F. Li

2016-06-01

Full Text Available Automatic semantic interpretation of street furniture has become a popular topic in recent years. Current studies detect street furniture as connected components of points above the street level. Street furniture classification based on properties of such components suffers from large intra class variability of shapes and cannot deal with mixed classes like traffic signs attached to light poles. In this paper, we focus on the decomposition of point clouds of pole-like street furniture. A novel street furniture decomposition method is proposed, which consists of three steps: (i acquirement of prior-knowledge, (ii pole extraction, (iii components separation. For the pole extraction, a novel global pole extraction approach is proposed to handle 3 different cases of street furniture. In the evaluation of results, which involves the decomposition of 27 different instances of street furniture, we demonstrate that our method decomposes mixed classes street furniture into poles and different components with respect to different functionalities.

Pole-Like Street Furniture Decompostion in Mobile Laser Scanning Data

Science.gov (United States)

Li, F.; Oude Elberink, S.; Vosselman, G.

2016-06-01

Automatic semantic interpretation of street furniture has become a popular topic in recent years. Current studies detect street furniture as connected components of points above the street level. Street furniture classification based on properties of such components suffers from large intra class variability of shapes and cannot deal with mixed classes like traffic signs attached to light poles. In this paper, we focus on the decomposition of point clouds of pole-like street furniture. A novel street furniture decomposition method is proposed, which consists of three steps: (i) acquirement of prior-knowledge, (ii) pole extraction, (iii) components separation. For the pole extraction, a novel global pole extraction approach is proposed to handle 3 different cases of street furniture. In the evaluation of results, which involves the decomposition of 27 different instances of street furniture, we demonstrate that our method decomposes mixed classes street furniture into poles and different components with respect to different functionalities.

Knee Angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers

Directory of Open Access Journals (Sweden)

Bart van Trigt

2018-05-01

Full Text Available The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation 1.7 years pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers.

Quiet swimming at low Reynolds number

Science.gov (United States)

Andersen, Anders; Wadhwa, Navish; Kiørboe, Thomas

2015-04-01

The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world.

A review of variables of urban street connectivity for spatial connection

International Nuclear Information System (INIS)

Mohamad, W S N W; Said, I

2014-01-01

Several studies on street connectivity in cities and towns have been modeled on topology, morphology, technology and psychology of people living in the urban environment. Street connectivity means the connection of streets that offers people alternative routes. However, there emerge difficulties to determine the suitable variables and analysis to be chosen in defining the accurate result for studies street connectivity. The aim of this paper is to identify variables of street connectivity by applying GIS and Space Syntax. This paper reviews the variables of street connectivity from 15 past articles done in 1990s to early 2000s from journals of nine disciplines on Environment and Behavior, Planning and Design, Computers, Environment and Urban Systems, Applied Earth Observation and Geo-information, Environment and Planning, Physica A: Statistical Mechanics and its Applications, Environmental Psychology, Social Science and Medicine and Building and Environment. From the review, there are four variables found for street connectivity: link (streets-streets, street-nodes or node-streets, nodes-nodes), accessibility, least-angle, and centrality. Space syntax and GIS are suitable tools to analyze the four variables relating to systematic street systems for pedestrians. This review implies that planners of the street systems, in the aspect of street connectivity in cities and towns, should consider these four variables

A review of variables of urban street connectivity for spatial connection

Science.gov (United States)

Mohamad, W. S. N. W.; Said, I.

2014-02-01

Several studies on street connectivity in cities and towns have been modeled on topology, morphology, technology and psychology of people living in the urban environment. Street connectivity means the connection of streets that offers people alternative routes. However, there emerge difficulties to determine the suitable variables and analysis to be chosen in defining the accurate result for studies street connectivity. The aim of this paper is to identify variables of street connectivity by applying GIS and Space Syntax. This paper reviews the variables of street connectivity from 15 past articles done in 1990s to early 2000s from journals of nine disciplines on Environment and Behavior, Planning and Design, Computers, Environment and Urban Systems, Applied Earth Observation and Geo-information, Environment and Planning, Physica A: Statistical Mechanics and its Applications, Environmental Psychology, Social Science and Medicine and Building and Environment. From the review, there are four variables found for street connectivity: link (streets-streets, street-nodes or node-streets, nodes-nodes), accessibility, least-angle, and centrality. Space syntax and GIS are suitable tools to analyze the four variables relating to systematic street systems for pedestrians. This review implies that planners of the street systems, in the aspect of street connectivity in cities and towns, should consider these four variables.

Sensation Seeking in Street Violence

DEFF Research Database (Denmark)

Heinskou, Marie Bruvik; Liebst, Lasse Suonperä

Sensation seeking leads to violence—runs an influential hypothesis in the social scientific study of violent behavior. Although studies confirm that violence is sometimes structured by sensation-seeking motives, the literature seldom comments on the limits to this explanation of violence....... The present study examines the scale of violence motivated by sensation seeking and the degree to which there are several distinct forms of sensation seeking motives operative in violence, rather than a sensation-seeking motive in the singular. The study draws on a sample of situations from Copenhagen...... involving street violence, which are coded quantitatively and qualitatively. Our analysis shows that sensation seeking only seldom seems to play a role in the structuring of street violence. Moreover, the data indicate that sensation seeking finds expression in street violence situations in two different...

The Fastskin Revolution From Human Fish to Swimming Androids

Directory of Open Access Journals (Sweden)

Jennifer Craik

2011-04-01

Full Text Available The story of fastskin swimsuits reflects some of the challenges facing the impact of technology in postmodern culture. Introduced in 1999 and ratified for the Sydney 2000 Olympic Games, fastskin swimsuits were touted as revolutionising competitive swimming. Ten years later, they were banned by the world’s swimming regulatory body FINA (the Fédération Internationale de Natation, with the ban taking effect from January 2010 (Shipley 2009. The reason was the controversy caused by the large number of world records that were broken by competitors wearing polyurethane swimsuits, the next generation of the original fast skin suits. These suits were deemed to be providing an artificial advantage by increasing buoyancy and reducing drag. This had been an issue ever since they were introduced, yet FINA had approved the suits and, thereby, unleashed an unstoppable technological revolution of the sport of competitive swimming. Underlying this was the issue about its implications of the transformation of a sport based on the movement of the human body through water without the aid of artificial devices or apparatus. This article argues that the advent of the fastskin has not only transformed the art of swimming but has created a new image of the swimmer as a virtual android rather than a human fish. In turn, the image of the sport of swimming has been re-mapped as a technical artefact and sci-fi spectacle based on a radically transformed concept of the swimming body as a material object that has implications for the ideal of the fashionable body.

Dynamic analysis of double-row self-aligning ball bearings due to applied loads, internal clearance, surface waviness and number of balls

Science.gov (United States)

Zhuo, Yaobin; Zhou, Xiaojun; Yang, Chenlong

2014-11-01

In this paper, a three degrees of freedom (dof) model was established for a double-row self-aligning ball bearing (SABB) system, and was applied to study the dynamic behavior of the system during starting process and constant speed rotating process. A mathematical model was developed concerning stiffness and damping characteristics of the bearing, as well as three-dimensional applied load, rotor centrifugal force, etc. Balls and races were all considered as nonlinear springs, and the contact force between ball and race was calculated based on classic Hertzian elastic contact deformation theory and deformation compatibility theory. The changes of each ball's contact force and loaded angle of each row were taken into account. In order to solve the nonlinear dynamical equilibrium equations of the system, these equations were rewritten as differential equations and the fourth order Runge-Kutta method was used to solve the equations iteratively. In order to verify accuracy of the dynamical model and correctness of the numerical solution method, a kind of SABB-BRF30 was chosen for case studies. The effects of several important governing parameters, such as radial and axial applied loads, normal internal, inner and outer races waviness, and number of balls were investigated. These parametric studies led to a complete characterization of the shaft-bearing system vibration transmission. The research provided a theoretical reference for new type bearing design, shaft-bearing system kinetic analysis, optimal design, etc.

An overview of Ball Aerospace cryogen storage and delivery systems

International Nuclear Information System (INIS)

Marquardt, J; Keller, J; Mills, G; Schmidt, J

2015-01-01

Starting on the Gemini program in the 1960s, Beech Aircraft (now Ball Aerospace) has been designing and manufacturing dewars for a variety of cryogens including liquid hydrogen and oxygen. These dewars flew on the Apollo, Skylab and Space Shuttle spacecraft providing fuel cell reactants resulting in over 150 manned spaceflights. Since Space Shuttle, Ball has also built the liquid hydrogen fuel tanks for the Boeing Phantom Eye unmanned aerial vehicle. Returning back to its fuel cell days, Ball has designed, built and tested a volume-constrained liquid hydrogen and oxygen tank system for reactant delivery to fuel cells on unmanned undersea vehicles (UUVs). Herein past history of Ball technology is described. Testing has been completed on the UUV specific design, which will be described. (paper)

Characteristics of flow and reactive pollutant dispersion in urban street canyons

Science.gov (United States)

Park, Soo-Jin; Kim, Jae-Jin; Kim, Minjoong J.; Park, Rokjin J.; Cheong, Hyeong-Bin

2015-05-01

In this study, the effects of aspect ratio defined as the ratio of building height to street width on the dispersion of reactive pollutants in street canyons were investigated using a coupled CFD-chemistry model. Flow characteristics for different aspect ratios were analyzed first. For each aspect ratio, six emission scenarios with different VOC-NOX ratios were considered. One vortex was generated when the aspect ratio was less than 1.6 (shallow street canyon). When the aspect ratio was greater than 1.6 (deep street canyon), two vortices were formed in the street canyons. Comparing to previous studies on two-dimensional street canyons, the vortex center is slanted toward the upwind building and reverse and downward flows are dominant in street canyons. Near the street bottom, there is a marked difference in flow pattern between in shallow and deep street canyons. Near the street bottom, reverse and downward flows are dominant in shallow street canyon and flow convergence exists near the center of the deep street canyons, which induces a large difference in the NOX and O3 dispersion patterns in the street canyons. NOX concentrations are high near the street bottom and decreases with height. The O3 concentrations are low at high NO concentrations near the street bottom because of NO titration. At a low VOC-NOX ratio, the NO concentrations are sufficiently high to destroy large amount of O3 by titration, resulting in an O3 concentration in the street canyon much lower than the background concentration. At high VOC-NOX ratios, a small amount of O3 is destroyed by NO titration in the lower layer of the street canyons. However, in the upper layer, O3 is formed through the photolysis of NO2 by VOC degradation reactions. As the aspect ratio increases, NOX (O3) concentrations averaged over the street canyons decrease (increase) in the shallow street canyons. This is because outward flow becomes strong and NOX flux toward the outsides of the street canyons increases

A Novel Generic Ball Recognition Algorithm Based on Omnidirectional Vision for Soccer Robots

Directory of Open Access Journals (Sweden)

Hui Zhang

2013-11-01

Full Text Available It is significant for the final goal of RoboCup to realize the recognition of generic balls for soccer robots. In this paper, a novel generic ball recognition algorithm based on omnidirectional vision is proposed by combining the modified Haar-like features and AdaBoost learning algorithm. The algorithm is divided into offline training and online recognition. During the phase of offline training, numerous sub-images are acquired from various panoramic images, including generic balls, and then the modified Haar-like features are extracted from them and used as the input of the AdaBoost learning algorithm to obtain a classifier. During the phase of online recognition, and according to the imaging characteristics of our omnidirectional vision system, rectangular windows are defined to search for the generic ball along the rotary and radial directions in the panoramic image, and the learned classifier is used to judge whether a ball is included in the window. After the ball has been recognized globally, ball tracking is realized by integrating a ball velocity estimation algorithm to reduce the computational cost. The experimental results show that good performance can be achieved using our algorithm, and that the generic ball can be recognized and tracked effectively.

A fish-like robot: Mechanics of swimming due to constraints

Science.gov (United States)

Tallapragada, Phanindra; Malla, Rijan

2014-11-01

It is well known that due to reasons of symmetry, a body with one degree of actuation cannot swim in an ideal fluid. However certain velocity constraints arising in fluid-body interactions, such as the Kutta condition classically applied at the trailing cusp of a Joukowski hydrofoil break this symmetry through vortex shedding. Thus Joukowski foils that vary shape periodically can be shown to be able to swim through vortex shedding. In general it can be shown that vortex shedding due to the Kutta condition is equivalent to nonintegrable constraints arising in the mechanics of finite-dimensional mechanical systems. This equivalence allows hydrodynamic problems involving vortex shedding, especially those pertaining to swimming and related phenomena to be framed in the context of geometric mechanics on manifolds. This formal equivalence also allows the design of bio inspired robots that swim not due to shape change but due to internal moving masses and rotors. Such robots lacking articulated joints are easy to design, build and control. We present such a fish-like robot that swims due to the rotation of internal rotors.

Energetics of swimming by the ferret: consequences of forelimb paddling.

Science.gov (United States)

Fish, Frank E; Baudinette, Russell V

2008-06-01

The domestic ferret (Mustela putorius furo) swims by alternate strokes of the forelimbs. This pectoral paddling is rare among semi-aquatic mammals. The energetic implications of swimming by pectoral paddling were examined by kinematic analysis and measurement of oxygen consumption. Ferrets maintained a constant stroke frequency, but increased swimming speed by increasing stroke amplitude. The ratio of swimming velocity to foot stroke velocity was low, indicating a low propulsive efficiency. Metabolic rate increased linearly with increasing speed. The cost of transport decreased with increasing swimming speed to a minimum of 3.59+/-0.28 J N(-1) m(-1) at U=0.44 m s(-1). The minimum cost of transport for the ferret was greater than values for semi-aquatic mammals using hind limb paddling, but lower than the minimum cost of transport for the closely related quadrupedally paddling mink. Differences in energetic performance may be due to the amount of muscle recruited for propulsion and the interrelationship hydrodynamic drag and interference between flow over the body surface and flow induced by propulsive appendages.

Diffusion of Complete Streets policies Across US communities.

Science.gov (United States)

Moreland-Russell, Sarah; Eyler, Amy; Barbero, Colleen; Hipp, J Aaron; Walsh, Heidi

2013-01-01

Complete Streets policies guide planning in communities by making the transportation system accommodating to all users including vehicle drivers, pedestrians, and bicyclists, as well as those using public transportation. While the number of Complete Streets policies has increased over the past decade, no research has explored the factors attributing to the widespread diffusion of these policies. The purpose of this study was to apply concepts of the Diffusion of Innovation Theory to data related to Complete Streets policies in order to identify potential patterns and correlates. The main outcome of this study was policy adoption. Using the Diffusion of Innovation Theory and results from previous literature, we identified several factors that had the potential to affect the rate of Complete Streets policy diffusion: rural/urban status, state obesity rate, state funding for transportation, state obesity prevention funding, percentage of people who walk or bike to work in the state, presence of a state Complete Streets policy, and the number of bordering communities with Complete Streets policy. We used event history analysis as the main analysis method. Data from 49 community-level policies were analyzed, with a "community" defined as a city, a county, or a regional/Metropolitan Planning Organization. Three variables were significant predictors of Complete Streets policy adoption: state obesity rate (odds ratio [OR] = 1.465; confidence interval [CI] = 1.10-1.96) percentage of people who bike or walk to work in the state (OR = 1.726; CI = 1.069-2.79), and presence of a border community with a Complete Streets policy (OR = 3.859; CI = 1.084-13.742). Communities with Complete Streets policies varied in geographic and sociodemographic factors. Information about communities that are more likely to adopt a policy can be a tool for advocates and policy makers interested in this topic. Because adoption does not imply implementation, further research is needed to study

Individuals with severely impaired vision can learn useful orientation and mobility skills in virtual streets and can use them to improve real street safety.

Science.gov (United States)

Bowman, Ellen Lambert; Liu, Lei

2017-01-01

Virtual reality has great potential in training road safety skills to individuals with low vision but the feasibility of such training has not been demonstrated. We tested the hypotheses that low vision individuals could learn useful skills in virtual streets and could apply them to improve real street safety. Twelve participants, whose vision was too poor to use the pedestrian signals were taught by a certified orientation and mobility specialist to determine the safest time to cross the street using the visual and auditory signals made by the start of previously stopped cars at a traffic-light controlled street intersection. Four participants were trained in real streets and eight in virtual streets presented on 3 projection screens. The crossing timing of all participants was evaluated in real streets before and after training. The participants were instructed to say "GO" at the time when they felt the safest to cross the street. A safety score was derived to quantify the GO calls based on its occurrence in the pedestrian phase (when the pedestrian sign did not show DON'T WALK). Before training, > 50% of the GO calls from all participants fell in the DON'T WALK phase of the traffic cycle and thus were totally unsafe. 20% of the GO calls fell in the latter half of the pedestrian phase. These calls were unsafe because one initiated crossing this late might not have sufficient time to walk across the street. After training, 90% of the GO calls fell in the early half of the pedestrian phase. These calls were safer because one initiated crossing in the pedestrian phase and had at least half of the pedestrian phase for walking across. Similar safety changes occurred in both virtual street and real street trained participants. An ANOVA showed a significant increase of the safety scores after training and there was no difference in this safety improvement between the virtual street and real street trained participants. This study demonstrated that virtual reality

Paramecium swimming in a capillary tube

Science.gov (United States)

Jana, Saikat; Jung, Sunghwan

2010-03-01

Micro-organisms exhibit different strategies for swimming in complex environments. Many micro-swimmers such as paramecium congregate and tend to live near wall. We investigate how paramecium moves in a confined space as compared to its motion in an unbounded fluid. A new theoretical model based on Taylor's sheet is developed, to study such boundary effects. In experiments, paramecia are put inside capillary tubes and their swimming behavior is observed. The data obtained from experiments is used to test the validity of our theoretical model and understand how the cilia influence the locomotion of paramecia in confined geometries.

Front crawl swimming analysis using accelerometers

DEFF Research Database (Denmark)

Espinosa, Hugo G; Nordsborg, Nikolai Baastrup; Thiel, David V

2015-01-01

Biomechanical characteristics such as stroke rate and stroke length can be used to determine the velocity of a swimmer and can be analysed in both a swimming pool and a flume. The aim of the present preliminary study was to investigate the differences between the acceleration data collected from...... a swimming pool with that collected from a flume, as a function of the swimmer's stroke rate and stroke count, with the objective of identifying the impact on the swimmer's performance. The differences were determined by the analysis of the stroke's features, comparing several strokes normalized to one...

Seasonality in swimming and cycling: Exploring a limitation of accelerometer based studies

Directory of Open Access Journals (Sweden)

Flo Harrison

2017-09-01

Full Text Available Accelerometer-based studies of children's physical activity have reported seasonal patterns in activity levels. However, the inability of many accelerometers to detect activity while the wearer is swimming or cycling may introduce a bias to the estimation of seasonality if participation in these activities are themselves seasonally patterned. We explore seasonal patterns in children's swimming and cycling among a sample of 7–8 year olds (N = 591 participating in the Millennium Cohort Study, UK. Participating children wore an accelerometer for one week on up to five occasions over the year and their parents completed a diary recording daily minutes spent swimming and cycling. Both swimming and cycling participation showed seasonal patterns, with 2.7 (SE 0.8 more minutes swimming and 5.7 (0.7 more minutes cycling performed in summer compared to winter. Adding swimming and cycling time to accelerometer-determined MVPA increased the summer-winter difference in MVPA from 16.6 (1.6 to 24.9 min. The seasonal trend in swimming and cycling appears to follow the same pattern as accelerometer-measured MVPA. Studies relying solely on accelerometers may therefore underestimate seasonal differences in children's activity.

Street Choice Logit Model for Visitors in Shopping Districts

Science.gov (United States)

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-01-01

In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive). PMID:25379274

Street Choice Logit Model for Visitors in Shopping Districts

Directory of Open Access Journals (Sweden)

Ko Kawada

2014-07-01

Full Text Available In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation. The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive and CARS (negative. Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive.

Health policy making for street children: challenges and strategies.

Science.gov (United States)

Abdi, Fatemeh; Saeieh, Sara Esmaelzadeh; Roozbeh, Nasibeh; Yazdkhasti, Mansoureh

2017-08-17

Background The phenomenon of street children is a bio-psychological and social issue that not only harms children, but also endangers the health of a society. In line with the national programs for the development and promotion of street children's health in Iran, health policy making and essential strategies for this group of children will be presented in this paper. This paper will discuss the main issues and challenges of street children's health and, also, health policy and guidelines for this population. Methods In this review study, the keywords; street children, health, challenges, policy, and health policy making were searched through PubMed, SID, Iranmedex, World Health Organization (WHO), Emro, the Cochran Library, Medline and Google scholar to collect data. The search resulted in 84 related resources from which 48 cases that were more relevant to this research and covered the issue more comprehensively, were used. All data published during 2002-2015 have been included in this paper. Results Key concepts including street children and their health, health policy, strategies to improve the health of street children, health policy approaches for street children, the WHO's strategies, and social support program for street children must be considered in the health policy making processes for street children, as precise identification of the relevant information makes planning more effective in health policy making for this group of children. Conclusion The phenomenon of street children is a growing problem in the world and it has turned into a serious concern in many countries including Iran. The findings of this study can be used for identifying necessary measures in order to use research outcomes more effectively in policy making processes and reforming street children's health policies in Iran.

Coronary ligation reduces maximum sustained swimming speed in Chinook salmon, Oncorhynchus tshawytscha

DEFF Research Database (Denmark)

Farrell, A P; Steffensen, J F

1987-01-01

The maximum aerobic swimming speed of Chinook salmon (Oncorhynchus tshawytscha) was measured before and after ligation of the coronary artery. Coronary artery ligation prevented blood flow to the compact layer of the ventricular myocardium, which represents 30% of the ventricular mass, and produced...... a statistically significant 35.5% reduction in maximum swimming speed. We conclude that the coronary circulation is important for maximum aerobic swimming and implicit in this conclusion is that maximum cardiac performance is probably necessary for maximum aerobic swimming performance....

Critical force during tethered swimming for the evaluation of aerobic capacity and prediction of performances in freestyle swimming

OpenAIRE

Marcelo Papoti; Ricardo Vitório; Gustavo Gomes Araújo; Luiz Eduardo Barreto Martins; Sérgio Augusto Cunha; Claudio Alexandre Gobatto

2010-01-01

The present study investigated the relationship of critical force (Fcrit) with lactate threshold (LLNA) and the intensity corresponding to VO2max (iVO2max) in tethered swimming (TS), and their correlation with maximal performance in 400-m (V400) and 30-min (VT30) freestyle swimming (FS). Seven swimmers were submitted to a TS incremental test for the determination of LLNA and iVO2max. For the determination of Fcrit, the swimmers performed four exercises to exhaustion at intensities (F) corresp...

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

Directory of Open Access Journals (Sweden)

David L Mann

Full Text Available Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i baseball and cricket batters cannot track the ball because it moves too quickly to be tracked by the eyes, and that consequently (ii batters do not - and possibly cannot - watch the ball at the moment they hit it. However, to date no studies have examined the gaze of truly elite batters. We examined the eye and head movements of two of the world's best cricket batters and found both claims do not apply to these batters. Remarkably, the batters coupled the rotation of their head to the movement of the ball, ensuring the ball remained in a consistent direction relative to their head. To this end, the ball could be followed if the batters simply moved their head and kept their eyes still. Instead of doing so, we show the elite batters used distinctive eye movement strategies, usually relying on two predictive saccades to anticipate (i the location of ball-bounce, and (ii the location of bat-ball contact, ensuring they could direct their gaze towards the ball as they hit it. These specific head and eye movement strategies play important functional roles in contributing towards interceptive expertise.

Micro-ball lens structure fabrication based on drop on demand printing the liquid mold

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaoyang, E-mail: zhuxy1026@163.com; Zhu, Li, E-mail: zhuli@njust.edu.cn; Chen, Hejuan; Yang, Lijun; Zhang, Weiyi

2016-01-15

Graphical abstract: - Highlights: • The glycerol micro-ball droplet was introduced to be as liquid mold to fabricate micro-ball lens. • A molding process was used to fabricate the micro-ball lens and the scales of them can be controlled. • The accurate molding process is mainly attributed to the ultrahigh adhesion of the treated substrate. • The micro-ball lenses with contact angle of 120° and 150° were fabricated, analyzed and discussed. - Abstract: In this paper, we demonstrated a simple micro-ball lens array (MBLA) fabrication method using a drop-on-demand (DOD) droplet printing technique and liquid mold. The micro-ball droplet array on the hydrophobic surface is used as the liquid mold to fabricate the MBLA. The ultrahigh adhesion force between the micro-ball droplet and the substrate is ascribed to the Wenzel state of the micro-ball droplet, while the replication process with low position error is attributed to the ultrahigh adhesion force between the micro-ball droplet and the substrate and the high viscosity of the micro-ball droplet and polydimethylsiloxane (PDMS) liquid. The micro-ball lenses (MBLs) with a contact angle of 120° and 150° were fabricated and the important fabrication details were discussed. The optical performance and scanning electron microscope (SEM) data of the MBLs showed that the MBLs had high quality surface morphology and good optical performance.

Predicting brain acceleration during heading of soccer ball

Science.gov (United States)

Taha, Zahari; Hasnun Arif Hassan, Mohd; Azri Aris, Mohd; Anuar, Zulfika

2013-12-01

There has been a long debate whether purposeful heading could cause harm to the brain. Studies have shown that repetitive heading could lead to degeneration of brain cells, which is similarly found in patients with mild traumatic brain injury. A two-degree of freedom linear mathematical model was developed to study the impact of soccer ball to the brain during ball-to-head impact in soccer. From the model, the acceleration of the brain upon impact can be obtained. The model is a mass-spring-damper system, in which the skull is modelled as a mass and the neck is modelled as a spring-damper system. The brain is a mass with suspension characteristics that are also defined by a spring and a damper. The model was validated by experiment, in which a ball was dropped from different heights onto an instrumented dummy skull. The validation shows that the results obtained from the model are in a good agreement with the brain acceleration measured from the experiment. This findings show that a simple linear mathematical model can be useful in giving a preliminary insight on what human brain endures during a ball-to-head impact.

Whose Bay Street? Competing Narratives of Nassau's City Centre

Directory of Open Access Journals (Sweden)

Nona Patara Martin

2009-05-01

Full Text Available Bay Street has always been at the centre of commercial, cultural and political life in the Bahama Islands. It also acts as a gateway for millions of tourists who come to Nassau, the Bahamian capital, via cruise ships every year. Not surprisingly, Bahamians and non-Bahamians have widely divergent impressions of Bay Street. The need to accommodate the tourists who are critical to the Bahamian economy has meant that Bay Street, despite its deep social significance for Bahamians, has increasingly become a tourist space. With reference to the ‘sense of place’ and place attachment literature, this paper traces the transformation of Bay Street and attempts to tease out the most obvious tensions between the Bay Street that Bahamians experience and Bay Street as a port of call.

Swimming attendance during childhood and development of asthma: Meta-analysis.

Science.gov (United States)

Valeriani, Federica; Protano, Carmela; Vitali, Matteo; Romano Spica, Vincenzo

2017-05-01

The association between asthma and swimming pool attendance has not been demonstrated and currently there are conflicting results. In order to clarify the association between asthma diagnosis in children and swimming pool attendance, and to assess the consistency of the available epidemiological studies, we completed a literature analysis on the relationship between the exposure to disinfection by-products in indoor swimming pools during childhood and asthma diagnosis. Following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria, a systematic review and meta-analysis was performed by searching MEDLINE via PubMed, TOXNET, and Scopus databases (from inception to 20 April 2015) using the key word "Asthma" together with "swimming pool", "disinfection by-products", "indoor air pollution" and "children". Inclusion criteria were: English language, a complete analytic study design involving a cohort of children (0-16 years), a well-defined definition of exposure, and the presence of data on effect and variance. Studies on in vivo, in vitro or professional and accidental exposure were excluded. After a screening process, seven reports (n = 5851 subjects) were included out of a total of 2928 references. The reported OR of the association between swimming pool attendance and asthma prevalence ranged from 0.58 to 2.30. The present meta-analysis failed to identify a significant difference in asthma development between children attending swimming pools and controls (OR, 1.084; 95% CI: 0.89-1.31). Swimming in childhood does not increase the likelihood of doctor-diagnosed asthma. Based on this meta-analysis review, the association of the disease with indoor pool attendance is still unclear. © 2016 Japan Pediatric Society.

Hydroacoustic measurement of swimming speed of North Sea saithe in the field

DEFF Research Database (Denmark)

Pedersen, Jan

2001-01-01

Saithe Pollachius virens, tracked diurnally with a split-beam echosounder. showed no relationship between size and swimming speed. The average and the median swimming speeds were 1.05 m s(-1) (+/- 0.09 m s (-1)) and 0.93 m a (-1). respectively. However. ping-to-ping speeds up to 3.34 m s (-1) were...... measured for 25-29 cm fish, whose swimming speeds were significantly higher at night (1.08 m s(-1)) than during the day (0.72 m s(- 1)). The high average swimming speed could be related to the: foraging or streaming part of the population and not to potential weakness of the methodology. However....... the uncertainty or target location increased with depth and resulted in calculated average swimming speeds of 0.15 m s(-1) even for a stationary target. With increasing swimming speed the average error decreased to Om s ' for speeds >0.34 m s(-1). Species identity was verified by trawling in a pelagic layer...

Thermal analyses of solar swimming pool heating in Pakistan

International Nuclear Information System (INIS)

Ahmad, I.

2011-01-01

Hotels and swimming clubs in Pakistan pay huge gas bills for heating Swimming pools in winter. Winter days in most parts of Pakistan remain sunny and unglazed low cost solar collectors may be used to extend the swimming season. Installing the pool in a wind-protected area, which receives unobstructed solar radiation, may further reduce the size of the solar collectors required to heat the swimming pools. The pools should be covered with plastic sheet to eliminate evaporative heat losses and to prevent dust and tree leaves falling in the pool. The results of the thermal analysis show that in some parts of the country, a solar exposed pool can maintain comfortable temperature simply by using a plastic sheet on the pool surface. On the other hand, there are cities where solar collector array equal to twice the surface area of the pool is required to keep desired temperature in winter. (author)

Alcohol in urban streetscapes: a comparison of the use of Google Street View and on-street observation

Directory of Open Access Journals (Sweden)

Chris Clews

2016-05-01

Full Text Available Abstract Background Alcohol-related harm is a major global health issue, and controls on alcohol marketing are one intervention utilized by governments. This study investigated the use of Google Street View (GSV as a novel research method for collecting alcohol-related data in the urban environment. Methods The efficacy of GSV and on-street observation by observer teams was compared by surveying 400 m stretches of 12 streets in Wellington, the capital city of New Zealand. Data on alcohol sale, alcohol-related advertising, health promotion materials, regulatory information and visible alcohol consumption were collected. Results A total of 403 retailers with evidence of alcohol sales and 1161 items of alcohol-related communication were identified in on-street observation. Of the latter, 1028 items (89 % were for alcohol marketing and 133 (11 % were for alcohol-related health promotion and alcohol regulation. GSV was found to be a less sensitive tool than on-street observation with only 50 % of the alcohol venues identified and 52 % of the venue-associated brand marketing identified. A high degree of inter-observer reliability was generally found between pairs of observers e.g., for the detection of alcohol retail venues the intra-class correlation coefficient (ICC was 0.93 (95 % CI: 0.78 to 0.98 for on-street observation and 0.85 (95 % CI: 0.49 to 0.96 for using GSV. Conclusions GSV does not seem suitable for the comprehensive study of the influences on alcohol consumption in the urban streetscape. However, it may still have value for large, static objects in the environment and be more time efficient than traditional on-street observation measures, especially when used to collect data across a wide geographical area. Furthermore, GSV might become a more useful research tool in settings with better image quality (such as more ‘footpath views’ and with more regularly updated GSV imagery.

The methodology of composing the exercises system with fit balls.

Directory of Open Access Journals (Sweden)

Voronov N.P.

2011-02-01

Full Text Available The original methodology of composing the exercises system with fit balls was considered. More than 10 publications were analysed. On the lesson with fit balls the problem was revealed. In the experiment took part 30 students at the age from 18 till 21. All the famous exercises were systematized. As a result, a big attractiveness and assimilability of the proposed complex was revealed. The effectiveness of the complex of physical exercises with fit balls for students was proved.

Multiple photoreceptor systems control the swim pacemaker activity in box jellyfish

DEFF Research Database (Denmark)

Garm, Anders Lydik; Mori, S.

2009-01-01

Like all other cnidarian medusae, box jellyfish propel themselves through the water by contracting their bell-shaped body in discrete swim pulses. These pulses are controlled by a swim pacemaker system situated in their sensory structures, the rhopalia. Each medusa has four rhopalia each with a s......Like all other cnidarian medusae, box jellyfish propel themselves through the water by contracting their bell-shaped body in discrete swim pulses. These pulses are controlled by a swim pacemaker system situated in their sensory structures, the rhopalia. Each medusa has four rhopalia each...... with a similar set of six eyes of four morphologically different types. We have examined how each of the four eye types influences the swim pacemaker. Multiple photoreceptor systems, three of the four eye types, plus the rhopalial neuropil, affect the swim pacemaker. The lower lens eye inhibits the pacemaker...... when stimulated and provokes a strong increase in the pacemaker frequency upon light-off. The upper lens eye, the pit eyes and the rhopalial neuropil all have close to the opposite effect. When these responses are compared with all-eye stimulations it is seen that some advanced integration must take...

Stimulated leaks found with SmartBall tool

Energy Technology Data Exchange (ETDEWEB)

Anon.

2011-05-15

Pure Technologies has developed a SmartBall leak detection tool which can be used in oil and gas pipelines. This tool contains acoustic sensors which listen for leaks and other problems in pipelines. Pig tracking units are used to track the tool along with receivers positioned on the pipe. With these technologies, SmartBall is able to detect small leaks that conventional methods would not detect and to assess their location accurately. Two runs on a Petrobras pipeline in Brazil highlighted the effectiveness of this technology, detecting three simulated leaks as small as 240mL/min. In addition, this system can give an estimation of the leak rate and traverse non piggable pipelines. Software is then used to analyze data and generate a report giving the size and location of the leaks identified. SmartBall is a technology capable of detecting small leaks and locating them in all sorts of oil and gas pipelines.

High-intensity high-volume swimming induces more robust signaling through PGC-1α and AMPK activation than sprint interval swimming in m. triceps brachii

DEFF Research Database (Denmark)

Casuso, Rafael A; Plaza-Díaz, Julio; Ruiz-Ojeda, Francisco J

2017-01-01

We aimed to test whether high-intensity high-volume training (HIHVT) swimming would induce more robust signaling than sprint interval training (SIT) swimming within the m. triceps brachii due to lower metabolic and oxidation. Nine well-trained swimmers performed the two training procedures...... on separate randomized days. Muscle biopsies from m. triceps brachii and blood samples were collected at three different time points: a) before the intervention (pre), b) immediately after the swimming procedures (post) and c) after 3 h of rest (3 h). Hydroperoxides, creatine kinase (CK), and lactate...

Petrography and microanalysis of Pennsylvanian coal-ball concretions (Herrin Coal, Illinois Basin, USA): Bearing on fossil plant preservation and coal-ball origins

Science.gov (United States)

Siewers, Fredrick D.; Phillips, Tom L.

2015-11-01

Petrographic analyses of 25 coal balls from well-studied paleobotanical profiles in the Middle Pennsylvanian Herrin Coal (Westphalian D, Illinois Basin) and five select coal balls from university collections, indicate that Herrin Coal-ball peats were permineralized by fibrous and non-fibrous carbonates. Fibrous carbonates occur in fan-like to spherulitic arrays in many intracellular (within tissue) pores, and are best developed in relatively open extracellular (between plant) pore spaces. Acid etched fibrous carbonates appear white under reflected light and possess a microcrystalline texture attributable to abundant microdolomite. Scanning electron microscopy, X-ray diffraction, and electron microprobe analysis demonstrate that individual fibers have a distinct trigonal prism morphology and are notable for their magnesium content (≈ 9-15 mol% MgCO3). Non-fibrous carbonates fill intercrystalline spaces among fibers and pores within the peat as primary precipitates and neomorphic replacements. In the immediate vicinity of plant cell walls, non-fibrous carbonates cut across fibrous carbonates as a secondary, neomorphic phase attributed to coalification of plant cell walls. Dolomite occurs as diagenetic microdolomite associated with the fibrous carbonate phase, as sparite replacements, and as void-filling cement. Maximum dolomite (50-59 wt.%) is in the top-of-seam coal-ball zone at the Sahara Mine, which is overlain by the marine Anna Shale. Coal-ball formation in the Herrin Coal began with the precipitation of fibrous high magnesium calcite. The trigonal prism morphology of the carbonate fibers suggests rapid precipitation from super-saturated, meteoric pore waters. Carbonate precipitation from marine waters is discounted on the basis of stratigraphic, paleobotanical, and stable isotopic evidence. Most non-fibrous carbonate is attributable to later diagenetic events, including void-fill replacements, recrystallization, and post-depositional fracture fills. Evidence

Effect of ball-milling to the surface morphology of CaCO3

Science.gov (United States)

Sulimai, N. H.; Rani, Rozina Abdul; Khusaimi, Z.; Abdullah, S.; Salifairus, M. J.; Alrokayan, Salman; Khan, Haseeb; Rusop, M.

2018-05-01

Calcium Carbonate can be synthesized in many approaches. This work studied on the physical changes to Calcium Carbonate (CaCO3) by ball-milling activity in different parameters; number of ball; collision duration; revolution per minute (RPM). Zirconia balls were used in the work because it has the best durability to withstand ball-milling conditions set. Industrial grade CaCO3 particles that were run in aforementioned parameters were characterized by Field Emission Scanning Electron Microscope (FE-SEM) to study the physical changes on the size and surface of the CaCO3. They were also characterized with Fourier Transform Infra-red Spectroscopy (FTIR) were fingerprint of CaCO3 regions were identified and any changes in the band position and intensity were discussed. Number of Zirconia balls and collision duration is directly proportional to the absorbance intensity whereas it is inversely proportional for the rpm. The best number of parameters producing the highest Absorbance is 100 Zirconia balls in duration of 1 hour and 100rpm.

Into a Mapping of Copenhagen Street Lighting 2014

DEFF Research Database (Denmark)

Bülow, Katja; Asp, Claus; Kongshaug, Jesper

LED lighting is a new lighting component in urban Spaces. How does LED lighting change the visual experience of a street, how did it use to be and how will it become? The book presents a mapping method in which an overview map of light sources in the Copenhagen streets is combined with a video...... recording and a series of photos from a route, whick goes through different city parts and types of streets. The mapping is done in the crucial changing fase, in which the street lighting in Copenhagen is a mix of previously used light sources and LED....

Is Swimming Safe in Heart Failure? A Systematic Review.

Science.gov (United States)

Shah, Parin; Pellicori, Pierpaolo; Macnamara, Alexandra; Urbinati, Alessia; Clark, Andrew L

It is not clear whether swimming is safe in patients with chronic heart failure. Ten studies examining the hemodynamic effects of acute water immersion (WI) (155 patients; average age 60 years; 86% male; mean left ventricular ejection fraction (LVEF) 29%) and 6 randomized controlled trials of rehabilitation comparing swimming with either medical treatment only (n = 3) or cycling (n = 1) or aerobic exercise (n = 2), (136 patients, average age 59 years; 84% male, mean LVEF 31%) were considered. In 7 studies of warm WI (30-35°C): heart rate (HR) fell (2% to -15%), and both cardiac output (CO) (7-37%) and stroke volume (SV) increased (13-41%). In 1 study of hot WI (41°C), systemic vascular resistance (SVR) fell (41%) and HR increased (33%). In 2 studies of cold WI (12-22°C), there were no consistent effects on HR and CO. Compared with medical management, swimming led to a greater increase in peak VO2 (7-14%) and 6 minute walk test (6MWT) (7-13%). Compared with cycle training, combined swimming and cycle training led to a greater reduction in resting HR (16%), a greater increase in resting SV (23%) and SVR (15%), but no changes in resting CO and a lesser increase in peak VO2 (6%). Compared with aerobic training, combined swimming and aerobic training lead to a reduction in resting HR (19%) and SVR (54%) and a greater increase in SV (34%), resting CO (28%), LVEF (9%), and 6MWT (70%). Although swimming appears to be safe, the studies conducted have been small, very heterogeneous, and inconclusive.

System Wide Information Management (SWIM)

Science.gov (United States)

Hritz, Mike; McGowan, Shirley; Ramos, Cal

2004-01-01

This viewgraph presentation lists questions regarding the implementation of System Wide Information Management (SWIM). Some of the questions concern policy issues and strategies, technology issues and strategies, or transition issues and strategies.

Swimming Training Reduces Neuroma Pain by Regulating Neurotrophins.

Science.gov (United States)

Tian, Jinge; Yu, Tingting; Xu, Yongming; Pu, Shaofeng; Lv, Yingying; Zhang, Xin; DU, Dongping

2018-01-01

Neuroma formation after peripheral nerve transection leads to severe neuropathic pain in amputees. Previous studies suggested that physical exercise could bring beneficial effect on alleviating neuropathic pain. However, the effect of exercise on neuroma pain still remained unclear. In addition, long-term exercise can affect the expression of neurotrophins (NT), such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), which play key roles in nociceptor sensitization and nerve sprouting after nerve injury. Here, we investigated whether long-term swimming exercise could relieve neuroma pain by modulating NT expression. We used a tibial neuroma transposition (TNT) rat model to mimic neuroma pain. After TNT surgery, rats performed swimming exercise for 5 wk. Neuroma pain and tactile sensitivities were detected using von Frey filaments. Immunofluorescence was applied to analyze neuroma formation. NGF and BDNF expressions in peripheral neuroma, dorsal root ganglion, and the spinal cord were measured using enzyme-linked immunosorbent assay and Western blotting. TNT led to neuroma formation, induced neuroma pain, and mechanical allodynia in hind paw. Five-week swimming exercise inhibited neuroma formation and relieved mechanical allodynia in the hind paw and neuroma pain in the lateral ankle. The analgesic effect lasted for at least 1 wk, even when the exercise ceased. TNT elevated the expressions of BDNF and NGF in peripheral neuroma, dorsal root ganglion, and the spinal cord to different extents. Swimming also decreased the elevation of NT expression. Swimming exercise not only inhibits neuroma formation induced by nerve transection but also relieves pain behavior. These effects might be associated with the modulation of NT.

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

NARCIS (Netherlands)

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

2013-01-01

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

The Impact of Immediate Verbal Feedback on the Improvement of Swimming Technique

Science.gov (United States)

Zatoń, Krystyna; Szczepan, Stefan

2014-01-01

The present research attempts to ascertain the impact of immediate verbal feedback (IVF) on modifications of stroke length (SL). In all swimming styles, stroke length is considered an essential kinematic parameter of the swimming cycle. It is important for swimming mechanics and energetics. If SL shortens while the stroke rate (SR) remains unchanged or decreases, the temporal-spatial structure of swimming is considered erroneous. It results in a lower swimming velocity. Our research included 64 subjects, who were divided into two groups: the experimental – E (n=32) and the control – C (n=32) groups. A pretest and a post-test were conducted. The subjects swam the front crawl over the test distance of 25m at Vmax. Only the E group subjects were provided with IVF aiming to increase their SL. All tests were filmed by two cameras (50 samples•s-1). The kinematic parameters of the swimming cycle were analyzed using the SIMI Reality Motion Systems 2D software (SIMI Reality Motion Systems 2D GmbH, Germany). The movement analysis allowed to determine the average horizontal swimming velocity over 15 meters. The repeated measures analysis of variance ANOVA with a post-hoc Tukey range test demonstrated statistically significant (pswimming velocity. IVF brought about a 6.93% (Simi method) and a 5.09% (Hay method) increase in SL, as well as a 2.92% increase in swimming velocity. PMID:25114741

Benefits and Enjoyment of a Swimming Intervention for Youth With Cerebral Palsy: An RCT Study.

Science.gov (United States)

Declerck, Marlies; Verheul, Martine; Daly, Daniel; Sanders, Ross

2016-01-01

To investigate enjoyment and specific benefits of a swimming intervention for youth with cerebral palsy (CP). Fourteen youth with CP (aged 7 to 17 years, Gross Motor Function Classification System levels I to III) were randomly assigned to control and swimming groups. Walking ability, swimming skills, fatigue, and pain were assessed at baseline, after a 10-week swimming intervention (2/week, 40-50 minutes) or control period, after a 5-week follow-up and, for the intervention group, after a 20-week follow-up period. The level of enjoyment of each swim-session was assessed. Levels of enjoyment were high. Walking and swimming skills improved significantly more in the swimming than in the control group (P = .043; P = .002, respectively), whereas fatigue and pain did not increase. After 20 weeks, gains in walking and swimming skills were retained (P = .017; P = .016, respectively). We recommend a swimming program for youth with CP to complement a physical therapy program.

Desipramine restricts estral cycle oscillations in swimming.

Science.gov (United States)

Contreras, C M; Martínez-Mota, L; Saavedra, M

1998-10-01

1. Desipramine (DMI) is a tricyclic antidepressant which reduces the immobility in rats forced to swim; however, it is unknown whether estral cycle phases impinge on DMI actions on immobility in daily swimming tests during several weeks. 2. In female wistar rats, vaginal smears taken before testing defined four estral phases. Afterwards, the authors assessed the latency for the first period of immobility in five-min forced swim tests practiced on 21-day DMI (DMI group), 21-day washout saline given after a 21-day DMI treatment (washout-saline group), or non-treated rats (control group). 3. We observed a longer latency for the first period of immobility in proestrus-estrus from the control and washout-saline groups. The 21-day treatment with DMI (2.1 mg/kg i.p., once a day) significantly (p estral cycle phase. 4. It is concluded that proestrus-estrus relates to increased struggling behavior. DMI enhances struggling behavior independently of hormonal state.

Do all frogs swim alike? The effect of ecological specialization on swimming kinematics in frogs

Czech Academy of Sciences Publication Activity Database

Robovská-Havelková, P.; Aerts, P.; Roček, Zbyněk; Přikryl, Tomáš; Fabre, A.-C.; Herrel, A.

2014-01-01

Roč. 217, č. 20 (2014), s. 3637-3644 ISSN 0022-0949 Institutional support: RVO:67985831 Keywords : Anura * kinematics * locomotion * swimming Subject RIV: EG - Zoology Impact factor: 2.897, year: 2014

POLE-LIKE STREET FURNITURE DECOMPOSTION IN MOBILE LASER SCANNING DATA

OpenAIRE

Li, F.; Oude Elberink, S.; Vosselman, G.

2016-01-01

Automatic semantic interpretation of street furniture has become a popular topic in recent years. Current studies detect street furniture as connected components of points above the street level. Street furniture classification based on properties of such components suffers from large intra class variability of shapes and cannot deal with mixed classes like traffic signs attached to light poles. In this paper, we focus on the decomposition of point clouds of pole-like street furniture. A nove...

To Swim or Not to Swim: Potential Transmission of Balaenophilus manatorum (Copepoda: Harpacticoida) in Marine Turtles.

Science.gov (United States)

Domènech, Francesc; Tomás, Jesús; Crespo-Picazo, José Luis; García-Párraga, Daniel; Raga, Juan Antonio; Aznar, Francisco Javier

2017-01-01

Species of Balaenophilus are the only harpacticoid copepods that exhibit a widespread, obligate association with vertebrates, i.e., B. unisetus with whales and B. manatorum with marine turtles and manatees. In the western Mediterranean, juveniles of the loggerhead sea turtle, Caretta caretta are the only available hosts for B. manatorum, which has been found occurring at high prevalence (>80%) on them. A key question is how these epibionts are transmitted from host to host. We investigated this issue based on experiments with live specimens of B. manatorum that were cultured with turtle skin. Specimens were obtained from head-started hatchlings of C. caretta from the western Mediterranean. Hatched nauplii crawled only on rough substrates and lacked the ability to swim. Only copepodites IV and V, and adults, were able to perform directional swimming. Legs 2, 3 and 4 played a major role in swimming and were only well-developed in these stages. Nauplii reared in wells with turtle skin readily fed on this item. Late copepodites and adults also fed on turtle skin but did not consume other potential food items such as fish skin, baleen plates or planktonic algae. Evidences suggest that the transmission of B. manatorum should rely on hosts' bodily contacts and/or swimming of late developmental stages between spatially close hosts. The possibility of long-ranged dispersal is unlikely for two reasons. First, all developmental stages seem to depend on turtle skin as a food resource. Second, the average clutch size of ovigerous females was small (turtles that occur at very low densities (turtles·km-2) in the western Mediterranean. The high prevalence of B. manatorum in loggerhead turtles in this area raises the question whether these turtles have contacts, or tend to closely aggregate, more than is currently believed.

To Swim or Not to Swim: Potential Transmission of Balaenophilus manatorum (Copepoda: Harpacticoida in Marine Turtles.

Directory of Open Access Journals (Sweden)

Francesc Domènech

Full Text Available Species of Balaenophilus are the only harpacticoid copepods that exhibit a widespread, obligate association with vertebrates, i.e., B. unisetus with whales and B. manatorum with marine turtles and manatees. In the western Mediterranean, juveniles of the loggerhead sea turtle, Caretta caretta are the only available hosts for B. manatorum, which has been found occurring at high prevalence (>80% on them. A key question is how these epibionts are transmitted from host to host. We investigated this issue based on experiments with live specimens of B. manatorum that were cultured with turtle skin. Specimens were obtained from head-started hatchlings of C. caretta from the western Mediterranean. Hatched nauplii crawled only on rough substrates and lacked the ability to swim. Only copepodites IV and V, and adults, were able to perform directional swimming. Legs 2, 3 and 4 played a major role in swimming and were only well-developed in these stages. Nauplii reared in wells with turtle skin readily fed on this item. Late copepodites and adults also fed on turtle skin but did not consume other potential food items such as fish skin, baleen plates or planktonic algae. Evidences suggest that the transmission of B. manatorum should rely on hosts' bodily contacts and/or swimming of late developmental stages between spatially close hosts. The possibility of long-ranged dispersal is unlikely for two reasons. First, all developmental stages seem to depend on turtle skin as a food resource. Second, the average clutch size of ovigerous females was small (< 70 eggs for free-living phases to successfully contact turtles that occur at very low densities (< 0.6 turtles·km-2 in the western Mediterranean. The high prevalence of B. manatorum in loggerhead turtles in this area raises the question whether these turtles have contacts, or tend to closely aggregate, more than is currently believed.

Street canyon ventilation control by proper planning and development

Directory of Open Access Journals (Sweden)

Balakin Vladimir Vasil'evich

2014-05-01

Full Text Available The objective of street canyon ventilation control in major streets is a tool of air pollution prevention in them, protection of housing areas from excessive wind or preservation and intensification of existing wind speed in case of insufficient ventilation. The maximum permissible concentration of car exhaust pollutants with wind speed within comfortable and permissible values by physiological and hygienic criteria, are ensured as from 40 to 70 % of thoroughfares in major cities. The dependence of air pollution level on wind speed is comparable to its dependence on traffic intensity and ratio of buildings height (H to street width. But one has to take into account that, if the wind blows across the street, vortices form within the street canyon, which results in higher concentration of car exhaust pollutants near the downwind buildings. The objective of this work is to find the functional dependences of wind speed in a major street on its width and density of buildings, and also to find out which street configurations are favorable for formation of closed air circulation within it, resulting in insufficient aeration. The experimental research was done on a site for large-scale modeling of built-up urban territory, using cup anemometers. The coefficients of dependence of wind speed within a street on the types of buildings and on the street width were obtained. Characteristics of street layouts for control of aeration were determined. Building density rates for maximizing or optimizing the wind speed were determined. Street layouts are considered where stable vortices form between the buildings. For example, vortices within the street canyon’s cross-section appear when buildings squarish in ground plan situated far apart are replaced by oblong ones with the minimum allowed intervals of 15 meters between them (for 5-storeyed buildings; or intervals equal to the buildings’ height, or where the buildings are long and close together. With

Street children of India -- a glimpse.

Science.gov (United States)

Nigam, S

1994-01-01

In India, 90% of street children are working children with regular family ties who live with their families, but are on the streets due to poverty and their parents' unemployment. The remaining 10% are either working children with few family ties who view the streets as their homes or abandoned and neglected children with no family ties. The National Policy for Children established in 1974 emphasizes the provision of equal opportunities for the development to all children during their growing years. Policy stresses programs to maintain, educate, and train destitute children and orphans. Policy is also to protect children against neglect, cruelty, and exploitation, but this is only on paper. An UNICEF study found that almost 40,000 children die every day in developing countries, 25% of whom are in India. Studies in some major cities indicate that the street children in India are of moderate health status, suffering from various chronic diseases and undernourishment. They are deprived of all health programs, but seem to prefer government hospitals in case of dire need. Street children often have to pay for water. Almost 97% in Calcutta, 99% in Bangalore, and 90% in Madras reported having no access to toilet and bathing facilities; 83% in Kanpur, however, had access to such facilities. Nothing has been heard in recent years of the National Children's Board established in 1975. Apparently the board has gradually waned. Various schemes were planned in 1992 by the Union Welfare Ministry in association with UNICEF. Extending extra health facilities, establishing nutrition programs, providing vocational training, protecting children from abuse, distributing dry-food polypacks, providing night shelters, providing ration cards, and creating bathing and toilet facilities would go far in improving the quality of life and the future of street children in India.

75 FR 71744 - Fifth Street Finance Corp., et al.; Notice of Application

Science.gov (United States)

2010-11-24

... Street Finance Corp., et al.; Notice of Application November 18, 2010. AGENCY: Securities and Exchange... Street Finance Corp. (``Fifth Street''), Fifth Street Management LLC, Fifth Street Mezzanine Partners IV... regulated as a business development company (``BDC'') under the Act. Fifth Street is a specialty finance...

EFFECTIVENESS OF DOUBLE WASH SWIM-UP VERSUS DOUBLE DENSITY GRADIENT SWIM-UP TECHNIQUE OF SPERM PREPARATION IN IN VITRO FERTILISATION

OpenAIRE

Srinivas Sangisapu; Sandeep Karunakaran; Ashok Kumar Pillai

2017-01-01

BACKGROUND Recovery of optimum number of good quality of spermatozoa is an important component of In Vitro Fertilisation (IVF). This is achieved by sperm preparation methods involving separation and recovery of capacitated sperms. Double Wash Swim-up (DWSU) and Double Density Gradient Swim-up (DDGSU) are two most accepted methods. Cochrane systematic review (2007) finds no clear benefit of one method over the other in Intrauterine Insemination (IUI). Systematic review on effective...

Study on water evaporation rate from indoor swimming pools

Directory of Open Access Journals (Sweden)

Rzeźnik Ilona

2017-01-01

Full Text Available The air relative humidity in closed spaces of indoor swimming pools influences significantly on users thermal comfort and the stability of the building structure, so its preservation on suitable level is very important. For this purpose, buildings are equipped with HVAC systems which provide adequate level of humidity. The selection of devices and their technical parameters is made using the mathematical models of water evaporation rate in the unoccupied and occupied indoor swimming pool. In the literature, there are many papers describing this phenomena but the results differ from each other. The aim of the study was the experimental verification of published models of evaporation rate in the pool. The tests carried out on a laboratory scale, using model of indoor swimming pool, measuring 99cm/68cm/22cm. The model was equipped with water spray installation with six nozzles to simulate conditions during the use of the swimming pool. The measurements were made for conditions of sports pools (water temperature 24°C and recreational swimming pool (water temperature 34°C. According to the recommendations the air temperature was about 2°C higher than water temperature, and the relative humidity ranged from 40% to 55%. Models Shah and Biasin & Krumm were characterized by the best fit to the results of measurements on a laboratory scale.

The Energy Cost of Running with the Ball in Soccer.