The Teen Science Café Network

Science.gov (United States)

Hall, M.; Mayhew, M. A.

2013-12-01

The 'Teen Cafè' phenomenon grew out of an NSF-funded experiment to bring the Cafè Scientifique model for engagement of the public with science and scientists to high school teenagers. Cafè Scientifique New Mexico (cafènm.org), now in its seventh year, has proven highly popular with high school teens for much the same reason as for adult Cafè programs: the blend of socializing in an attractive venue and interaction with a scientist on an interesting science topic. Teen Cafés also include exploration of the topic with hands-on activities. The success of the model has led to the creation of the national Teen Science Cafè Network (teensciencecafe.org. This first year of the new program, four 'Founding Members' of the Network-- in Florida, Colorado, North Carolina, and the St. Louis, Missouri region--started up Teen Cafè programs. Each applied the model with a unique flair appropriate to local institutions and demographics. Each Member in the Network runs Cafès in multiple local venues. We are now gearing up for our second year, and the Network is growing. Our Teen Cafè topics have covered a very wide range, from belly-button biodiversity to cyber-security to patterns of mega-earthquakes to a day in the life of a teen dolphin to corals on acid to emergency room medicine to alternative fuel cars. Presenters have come from a great variety of local institutions. Though they are popular with teens because they are fun and interesting, our evaluations have demonstrated that the programs are having a significant impact on participating teens' understanding of the nature of science, the work that scientists do, and the importance of science to their daily lives. We are also having success in training scientists to communicate effectively with this public audience. Presenters report strong satisfaction with their resulting quality of science communication. A surprising number have reported that their experience with the program has led them to think in a new way about

Influence of physical development on start and countermovement jump performance in adolescent sprint athletes.

Science.gov (United States)

Aerenhouts, D; Debaere, S; Hagman, F; Van Gheluwe, B; Delecluse, C; Clarys, P

2013-02-01

The aim of the present study was to describe the effect of physical changes during adolescence on sprint start and countermovement jump (CMJ) performance. Twenty-eight girls and 25 boys (15.0±1.6 and 14.7±1.9 years at start respectively) were measured twice with a one year interval. Anthropometric data allowed skeletal muscle mass (SMM) estimation. Athletes performed a 10m sprint tracked from behind by a laser sensor, with starting blocks measuring propulsion forces. CMJ's were performed on a Kistler force plate. Between the two measurement occasions both genders increased in body height, weight and SMM. In girls and boys, impulse during the push-off, block leaving velocity and times at 5 and 10 m improved significantly. In both genders CMJ absolute power increased but not power.kg-1. Only in boys a higher CMJ was registered on occasion 2. For both genders on both occasions, impulse during the push-off correlated with body weight, SMM and CMJ power (r from .46 to .84), and in boys also with CMJ height and CMJ power.kg-1 (r from 0.43 to 0.76). Boys showed CMJ height and power to correlate with 5 and 10 m times (r from -0.42 to -0.79) and with block leaving velocity, however only on the first data collection (r=0.61 and 0.59, respectively). Sprint start performance is only partly related to muscular development and CMJ could predict start performance in boys only. Sprint start and CMJ rely on technical skills and, therefore, increasing muscularity should be accompanied with sufficient specific training to allow an optimal transfer to start performance.

Jumping on water

Science.gov (United States)

Kim, Ho-Young

2016-11-01

Water striders can jump on water as high as they can jump on land. Quick jumps allow them to avoid sudden dangers such as predators' attacks, and therefore understanding how they make such a dramatic motion for survival can shed light on the ultimate level of semi-aquatic motility achievable through evolution. However, the mechanism of their vertical jumping from a water surface has eluded hydrodynamic explanations so far. By observing movements of water strider legs and theoretically analyzing their dynamic interactions with deforming liquid-air interface, we have recently found that different species of jumping striders always tune their leg rotation speed with a force just below that required to break the water surface to reach the maximum take-off velocity. Here, we start with discussing the fundamental theories of dynamics of floating and sinking of small objects. The theories then enable us to analyze forces acting on a water strider while it presses down the water surface to fully exploit the capillary force. We further introduce a 68-milligram at-scale robotic insect capable of jumping on water without splash, strikingly similar to the real strider, by utilizing the water surface just as a trampoline.

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

Science.gov (United States)

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

2017-11-22

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

Birth of a hydraulic jump

Science.gov (United States)

Duchesne, Alexis; Bohr, Tomas; Andersen, Anders

2017-11-01

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

Teen Smoking

Science.gov (United States)

... Tween and teen health Want to prevent teen smoking? Understand why teens smoke and how to talk ... teen about cigarettes. By Mayo Clinic Staff Teen smoking might begin innocently, but it can become a ...

Parent-teen worry about the teen contracting AIDS.

Science.gov (United States)

Carroll, R M; Shepard, M P; Mahon, M M; Deatrick, J A; Orsi, A J; Moriarty, H J; Feetham, S L

1999-04-01

A secondary data analysis of the National Commission on Children: 1990 Survey of Parents and Children was conducted with a subsample of 457 parent-teen pairs who responded to the "worry about AIDS" question. The teen's worry about contracting AIDS was associated with race, parent's education, the amount of discipline from the parent for engaging in sex, the teen's desire to talk to the parent about the problem of sex, the teen's rating of the neighborhood as a safe place to grow up, whether the parent listened to the teen's telephone interview, and the parent's response to whether his or her teen had a history of sexually transmitted disease. Of the parent-teen pairs in the subsample, 46% (N = 210) agreed in their responses about worry. Agreement was more frequent among the parent-teen pairs when compared to randomly constructed surrogate pairs. Dyadic analysis supported a family system view of perceived susceptibility.

Jump2Health Website™ for Head Start parents to promote a healthy home environment: Results from formative research.

Science.gov (United States)

Gurajada, Navya; Reed, Debra B; Taylor, Ashlee L

2017-12-13

Background: In US, approximately 23% of children between the ages of 2-5 years are overweight or obese. Parents need access to information to create healthy home environments for obesity prevention, yet participation for in-person education programs is challenging. Web-based interventions are promising educational tools due to 24/7 availability. However, information is limited on their development and evaluation. Design and Methods: This study reports on a rigorous development process that included six focus group discussions (FGD) with stakeholders (three FGD each with parents and teachers) to assess education needs and inform the development of the Jump2Health Website ™ by a multidisciplinary team. After development, the Website was evaluated by telephone interviews with stakeholders (five parents and six teachers) and reviewed by an expert panel of five Registered Dietitians. Results: Twenty Head Start parents and 22 Head Start teachers participated in the FGD. To address the needs identified by these stakeholders, the Website was designed to include components that were enabling and motivating, such as descriptions of health benefits by achieving the desired behaviours, short videos on easy meal preparation, and tip sheets on how to achieve healthy behaviours in easy, economical ways. Stakeholder evaluation of the Website indicated that the information was helpful, easy to use, and would be beneficial for parents. Conclusions: The development of Jump2Health Website ™ was strengthened by FGD with stakeholders that assessed educational needs. Interviews with stakeholders and an expert panel review showed that the Website may be an effective educational method to teach parents about healthy behaviours related to obesity prevention.

Jump2Health Website™ for Head Start parents to promote a healthy home environment: Results from formative research

Directory of Open Access Journals (Sweden)

Navya Gurajada

2017-12-01

Full Text Available Background: In US, approximately 23% of children between the ages of 2-5 years are overweight or obese. Parents need access to information to create healthy home environments for obesity prevention, yet participation for in-person education programs is challenging. Web-based interventions are promising educational tools due to 24/7 availability. However, information is limited on their development and evaluation. Design and Methods: This study reports on a rigorous development process that included six focus group discussions (FGD with stakeholders (three FGD each with parents and teachers to assess education needs and inform the development of the Jump2Health Website™ by a multidisciplinary team. After development, the Website was evaluated by telephone interviews with stakeholders (five parents and six teachers and reviewed by an expert panel of five Registered Dietitians. Results: Twenty Head Start parents and 22 Head Start teachers participated in the FGD. To address the needs identified by these stakeholders, the Website was designed to include components that were enabling and motivating, such as descriptions of health benefits by achieving the desired behaviours, short videos on easy meal preparation, and tip sheets on how to achieve healthy behaviours in easy, economical ways. Stakeholder evaluation of the Website indicated that the information was helpful, easy to use, and would be beneficial for parents. Conclusions: The development of Jump2Health Website™ was strengthened by FGD with stakeholders that assessed educational needs. Interviews with stakeholders and an expert panel review showed that the Website may be an effective educational method to teach parents about healthy behaviours related to obesity prevention.

Jump start: a targeted substance abuse prevention program.

Science.gov (United States)

Harrington, N G; Donohew, L

1997-10-01

A substance abuse prevention and life skills program for economically disadvantaged, high sensation seeking African American teens was developed and tested in Cincinnati, Ohio. Formative research was conducted to determine program content and format. Over two implementations, 289 individuals in the target population were recruited as participants for the field test of the program. For the first implementation, participants were randomly selected from the city's summer youth employment program. For the second, a media campaign was designed to recruit participants. Process evaluation indicated that participants evaluated the program extremely positively. Outcome evaluation indicated that significant pretest differences between high and low sensation seekers were neutralized for liquor and marijuana in both years of the program and for attitude toward drugs in the first year of the program. These results suggest that sensation seeking is a useful message design and audience-targeting variable for substance abuse prevention program design. Implications and recommendations for future research are discussed.

Human Long Jump — A Deductive Approach

Directory of Open Access Journals (Sweden)

Miloš Jovanović

2012-10-01

Full Text Available This paper presents a useful application of a generalized approach to the modelling of human and humanoid motion using the deductive approach. It starts with formulating a completely general problem and deriving different real situations as special cases. The concept and the software realization are verified by comparing the results with the ones obtained using “classical” software for one well-known particular problem – biped walking. New applicability and potentials of the proposed method are demonstrated by simulation of a selected example – the long jump. The simulated motion included jumping and landing on the feet (after a jump. Additional analysis is done in the paper regarding the joint torque and joint angle during the jumping. Separate stages of the simulation are defined and explained.

Parent and teen agreement on driving expectations prior to teen licensure.

Science.gov (United States)

Hamann, Cara J; Ramirez, Marizen; Yang, Jingzhen; Chande, Vidya; Peek-Asa, Corinne

2014-01-01

To examine pre-licensure agreement on driving expectations and predictors of teen driving expectations among parent-teen dyads. Cross-sectional survey of 163 parent-teen dyads. Descriptive statistics, weighted Kappa coefficients, and linear regression were used to examine expectations about post-licensure teen driving. Teens reported high pre-licensure unsupervised driving (N = 79, 48.5%) and regular access to a car (N = 130, 81.8%). Parents and teens had low agreement on teen driving expectations (eg, after dark, κw = 0.23). Each time teens currently drove to/from school, their expectation of driving in risky conditions post-licensure increased (β = 0.21, p = .02). Pre-licensure improvement of parent-teen agreement on driving expectations are needed to have the greatest impact on preventing teens from driving in high risk conditions.

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

NARCIS (Netherlands)

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

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

Stereofractographic investigation of static start and dynamic jump of a fatigue crack in pressure vessel steel

International Nuclear Information System (INIS)

Stepanenko, V.A.; Shtukaturova, A.S.; Yasnij, P.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti)

1983-01-01

Results of investigaytion have been discussed ipto the effect of certain temperature-force factors on regularities in the formation of stretch zones during the crack initiation static and transition zones at crack jumps in the process of cyclic loading. The 15Kh2NMFA pressure vessel steel has been investigated. The steel fracture toughnesKub(Ic) has been determined testing s the specimens for excentric stretching or a bending through an angle. It has been shown that transition zones in a front of fatique cracks at the jump beginning and end are formed through the shift mechanism owing to the material separation along the maximum failure zone contour, i.e. along the plastic zone contour in a crack vertex. This is the mait difference of regularities in the formation of the transition zones during fatique crack jumps from stretching zones formed through the break-away mechanism of crack vertex bluntness during its static move. It is noted that a final conclusion on the mechanism of transition zone formation during fartique crack jumps allows one to perform systematic investigation into the plastic zone configuration in a fatique crack verteX and stereofractographic measurement of two identically conjugate jump surfaces on opposite fractures of the same samples

How to Run Successful Teen Volunteer Programs - Forms for teen volunteers and teen advisory groups (TAG) -Powerpoint Presentations

OpenAIRE

Donald, Sarah; Donoghue, Vicki; Dawley, Amy

2010-01-01

Based on work with teen volunteers, teen advisory councils, teen reading buddy programs and anime and manga clubs, Sarah Donald, Vicki Donoghue and Amy Dawley discuss their successes with teenagers, and practical ways to serve teens in the community.

Bilateral contact ground reaction forces and contact times during plyometric drop jumping.

Science.gov (United States)

Ball, Nick B; Stock, Christopher G; Scurr, Joanna C

2010-10-01

Drop jumping (DJ) is used in training programs aimed to improve lower extremity explosive power. When performing double-leg drop jumps, it is important to provide an equal stimulus to both legs to ensure balanced development of the lower legs. The aim of this study was to bilaterally analyze the ground reactions forces and temporal components of drop jumping from 3 heights. Ten recreationally active male subjects completed 3 bounce-drop jumps from 3 starting heights (0.2, 0.4, and 0.6 m). Two linked force platforms were used to record left- and right-leg peak vertical force, time to peak force, average force, ground contact time, impulse and time differential. Between-height and between-leg comparisons for each variable were made using a multivariate analysis of variance with post hoc Wilcoxon tests (p < 0.05). Results indicated that force and time variables increased as drop jump height increased (p < 0.0001). Post hoc analyses showed that at 0.2- and 0.4-m bilateral differences were present in the time to peak force, average force, and impulse. No bilateral differences for any variables were shown at 0.6-m starting height. The contact time for all jumps was <0.26 seconds. At 0.2 m, only 63% of the subjects had a starting time differential of <0.01 seconds, rising to 96.3% at 0.6 m. The results indicated that 0.6 m is the suggested drop jump height to ensure that no bilateral differences in vertical forces and temporal components occur; however, shorter contact times were found at the lower heights.

Significant reduction of repeat teen pregnancy in a comprehensive young parent program.

Science.gov (United States)

Omar, H A; Fowler, A; McClanahan, K K

2008-10-01

To describe a comprehensive, multidisciplinary approach to teen mothers and their children that significantly reduces repeat pregnancies. Retrospective review of repeat teen pregnancy data. Young Parent Program (YPP) at a university-based health center. 1386 teen mothers between the ages of 11 and 19 who participated in the YPP for at least three years. Comprehensive Care: for both teen mother and her baby, including prenatal and postnatal care, preventive care, reproductive services, mental health, and acute care visits. Family counseling and similar services were also provided to siblings of the teen. CONTINUITY OF CARE: Patients are seen by the same staff and attending physicians on each visit. The treatment team includes physicians, nurses, social worker, nutritionist, and psychologist, all of whom are available to provide care at each visit. Flexible hours: Including evening clinic to allow teens to attend school or work during the day. Financial incentive: Patients with no insurance are given free contraceptives and a "no charge" clinic visit. Extensive contraceptive counseling is provided prior to start of contraceptive use and at every clinic visit. Routine telephone and/or mail reminders of appointments Rate of repeat teen pregnancy. Only 11(.79%) had repeat pregnancies. Older youth appeared more likely to repeat a pregnancy. Comprehensive intervention for teen mothers can be very successful in reducing repeat teen pregnancy in those teens who participate consistently in the program over a period of years.

pH-jump induced α-helix folding of poly-L-glutamic acid

International Nuclear Information System (INIS)

Donten, Mateusz L.; Hamm, Peter

2013-01-01

Highlights: ► pH-jump as truly biomimetic tool to initiate non-equilibrium dynamics of biomolecules. ► Design criteria to widen the applicability of pH-jumps are developed. ► Folding of poly-L-Glu in dependence of starting pH, pH jump size and helix length. ► Length dependence provides strong evidence for a nucleation–propagation scenario. - Abstract: pH jumps are a truly biomimetic technique to initiate non-equilibrium dynamics of biomolecules. In this work, the pH jump induced α-helix folding of poly-L-glutamic acid is investigated upon proton release from o-nitrobenzaldehyde. The aim of this work is twofold: On the one hand, design criteria of pH jump experiments are discussed, on the other hand, the folding mechanism of poly-L-glutamic acid is clarified by probing the IR response of the amide I band. Its folding kinetics is studied in dependence of the starting pD, the size of the pD jump and the length of the helix. While no dependence on the first two parameters could be detected, the folding time varies from 0.6 μs to 1.8 μs for helix lengths of 20 residue to 440 residue, respectively. It converges to a long-length limit at about 50 residue, a result which is attributed to a nucleation–propagation mechanism

Teen Suicide

Science.gov (United States)

... episodes, or a mix of both types. Some teens will try to hide depression or thoughts of suicide. They might withdraw, or act out. This can ... teen depression? What should I do if my teen is depressed? Did I do ... antidepressants cause suicide? Once my teenager is treated for suicide or ...

Study of brittle crack jump rate using acoustic emission method

International Nuclear Information System (INIS)

Yasnij, P.V.; Pokrovskij, V.V.; Strizhalo, V.A.; Dobrovol'skij, Yu.V.

1987-01-01

A new peocedure is elaborated to detect brittle jumps of small length (0.1...5mm) occuring both inside the specimen and along the crack front under static and cyclic loading using the phenomena of acoustic emission (AE). Recording of the crack start and stop moments with an AE sensor as well as evaluation of the brittle crack jump length by the after-failure specimen fracture make it possible to find the mean crack propagation rate. Experimental dependences are obtained for the crack propagation rate with a brittle crack jump in steel 15Kh2MFA (σ B =1157 MPa, σ 0.2 =100 MPa) at 293 K and under cyclic loading as a function of the jump length and also as a function of the critical stress intensity factor K jc i corresponding to the crack jump

Recognizing teen depression

Science.gov (United States)

... medlineplus.gov/ency/patientinstructions/000648.htm Recognizing teen depression To use the sharing features on this page, ... life. Be Aware of the Risk for Teen Depression Your teen is more at risk for depression ...

Teen Dating Violence

Science.gov (United States)

... Room Social Media Publications Injury Center Teen Dating Violence Recommend on Facebook Tweet Share Compartir On This ... serious forms of violence. What is teen dating violence? Teen Dating Violence [550 KB, 2 Pages, 508] ...

Teen Pregnancy and Childbearing

Science.gov (United States)

... Pregnancy has sub items, Reproductive Health & Teen Pregnancy Contraceptive Use STDs Teen Pregnancy & Childbearing Teen Pregnancy Prevention Program Trends Negative Impacts Strategies & Approaches for Prevention Engaging Adolescent Males in Prevention Tips for Parents of Teens ...

Helping your teen with depression

Science.gov (United States)

Teen depression - helping; Teen depression - talk therapy; Teen depression - medicine ... teen the most. The most effective treatments for depression are: Talk therapy Antidepressant medicines If your teen ...

Accuracy of Jump-Mat Systems for Measuring Jump Height.

Science.gov (United States)

Pueo, Basilio; Lipinska, Patrycja; Jiménez-Olmedo, José M; Zmijewski, Piotr; Hopkins, Will G

2017-08-01

Vertical-jump tests are commonly used to evaluate lower-limb power of athletes and nonathletes. Several types of equipment are available for this purpose. To compare the error of measurement of 2 jump-mat systems (Chronojump-Boscosystem and Globus Ergo Tester) with that of a motion-capture system as a criterion and to determine the modifying effect of foot length on jump height. Thirty-one young adult men alternated 4 countermovement jumps with 4 squat jumps. Mean jump height and standard deviations representing technical error of measurement arising from each device and variability arising from the subjects themselves were estimated with a novel mixed model and evaluated via standardization and magnitude-based inference. The jump-mat systems produced nearly identical measures of jump height (differences in means and in technical errors of measurement ≤1 mm). Countermovement and squat-jump height were both 13.6 cm higher with motion capture (90% confidence limits ±0.3 cm), but this very large difference was reduced to small unclear differences when adjusted to a foot length of zero. Variability in countermovement and squat-jump height arising from the subjects was small (1.1 and 1.5 cm, respectively, 90% confidence limits ±0.3 cm); technical error of motion capture was similar in magnitude (1.7 and 1.6 cm, ±0.3 and ±0.4 cm), and that of the jump mats was similar or smaller (1.2 and 0.3 cm, ±0.5 and ±0.9 cm). The jump-mat systems provide trustworthy measurements for monitoring changes in jump height. Foot length can explain the substantially higher jump height observed with motion capture.

Teen pregnancy: an update.

Science.gov (United States)

McCracken, Katherine A; Loveless, Meredith

2014-10-01

To provide clinicians with a review of recent research and clinically applicable tools regarding teen pregnancy. Teen pregnancy rates have declined but still remain a significant problem in the USA. Teen pregnancy prevention was identified by Centers for Disease Control and Prevention as one of its top six priorities, which is increasing research and intervention data. Long-acting contraceptive methods are acceptable to teens and have been shown to reduce teen birth rates. Pregnant teens need special attention to counseling on pregnancy options and reducing risk during pregnancy with regular prenatal care. Postpartum teens should be encouraged and supported to breastfeed, monitored for depression, and have access to reliable contraception to avoid repeat undesired pregnancy. This review highlights important issues for all providers caring for female adolescents and those who may encounter teen pregnancy. Foremost prevention of teen pregnancy by comprehensive sexual education and access to contraception is the priority. Educating patients and healthcare providers about safety and efficacy of long-acting reversible contraception is a good step to reducing undesired teen pregnancies. Rates of postpartum depression are greater in adolescents than in adults, and adolescent mothers need to be screened and monitored for depression. Strategies to avoid another undesired pregnancy shortly after delivery should be implemented.

the Modeling of Hydraulic Jump Generated Partially on Sloping Apron

Directory of Open Access Journals (Sweden)

Shaker Abdulatif Jalil

2017-12-01

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

Correlates and consequences of parent-teen incongruence in reports of teens' sexual experience.

Science.gov (United States)

Mollborn, Stefanie; Everett, Bethany

2010-07-01

Using the National Longitudinal Study of Adolescent Health, factors associated with incongruence between parents' and adolescents' reports of teens' sexual experience were investigated, and the consequences of inaccurate parental knowledge for adolescents' subsequent sexual behaviors were explored. Most parents of virgins accurately reported teens' lack of experience, but most parents of teens who had had sex provided inaccurate reports. Binary logistic regression analyses showed that many adolescent-, parent-, and family-level factors predicted the accuracy of parents' reports. Parents' accurate knowledge of their teens' sexual experience was not found to be consistently beneficial for teens' subsequent sexual outcomes. Rather, parents' expectations about teens' sexual experience created a self-fulfilling prophecy, with teens' subsequent sexual outcomes conforming to parents' expectations. These findings suggest that research on parent-teen communication about sex needs to consider the expectations being expressed, as well as the information being exchanged.

Effects of timing of signal indicating jump directions on knee biomechanics in jump-landing-jump tasks.

Science.gov (United States)

Stephenson, Mitchell L; Hinshaw, Taylour J; Wadley, Haley A; Zhu, Qin; Wilson, Margaret A; Byra, Mark; Dai, Boyi

2018-03-01

A variety of the available time to react (ATR) has been utilised to study knee biomechanics during reactive jump-landing tasks. The purpose was to quantify knee kinematics and kinetics during a jump-land-jump task of three possible directions as the ATR was reduced. Thirty-four recreational athletes performed 45 trials of a jump-land-jump task, during which the direction of the second jump (lateral, medial or vertical) was indicated before they initiated the first jump, the instant they initiated the first jump, 300 ms before landing, 150 ms before landing or at the instant of landing. Knee joint angles and moments close to the instant of landing were significantly different when the ATR was equal to or more than 300 ms before landing, but became similar when the ATR was 150 ms or 0 ms before landing. As the ATR was decreased, knee moments decreased for the medial jump direction, but increased for the lateral jump direction. When the ATR is shorter than an individual's reaction time, the movement pattern cannot be pre-planned before landing. Knee biomechanics are dependent on the timing of the signal and the subsequent jump direction. Precise control of timing and screening athletes with low ATR are suggested.

Data-Driven Jump Detection Thresholds for Application in Jump Regressions

Directory of Open Access Journals (Sweden)

Robert Davies

2018-03-01

Full Text Available This paper develops a method to select the threshold in threshold-based jump detection methods. The method is motivated by an analysis of threshold-based jump detection methods in the context of jump-diffusion models. We show that over the range of sampling frequencies a researcher is most likely to encounter that the usual in-fill asymptotics provide a poor guide for selecting the jump threshold. Because of this we develop a sample-based method. Our method estimates the number of jumps over a grid of thresholds and selects the optimal threshold at what we term the ‘take-off’ point in the estimated number of jumps. We show that this method consistently estimates the jumps and their indices as the sampling interval goes to zero. In several Monte Carlo studies we evaluate the performance of our method based on its ability to accurately locate jumps and its ability to distinguish between true jumps and large diffusive moves. In one of these Monte Carlo studies we evaluate the performance of our method in a jump regression context. Finally, we apply our method in two empirical studies. In one we estimate the number of jumps and report the jump threshold our method selects for three commonly used market indices. In the other empirical application we perform a series of jump regressions using our method to select the jump threshold.

Mobile Jump Assessment (mJump): A Descriptive and Inferential Study.

Science.gov (United States)

Mateos-Angulo, Alvaro; Galán-Mercant, Alejandro; Cuesta-Vargas, Antonio

2015-08-26

Vertical jump tests are used in athletics and rehabilitation to measure physical performance in people of different age ranges and fitness. Jumping ability can be analyzed through different variables, and the most commonly used are fly time and jump height. They can be obtained by a variety of measuring devices, but most are limited to laboratory use only. The current generation of smartphones contains inertial sensors that are able to record kinematic variables for human motion analysis, since they are tools for easy access and portability for clinical use. The aim of this study was to describe and analyze the kinematics characteristics using the inertial sensor incorporated in the iPhone 4S, the lower limbs strength through a manual dynamometer, and the jump variables obtained with a contact mat in the squat jump and countermovement jump tests (fly time and jump height) from a cohort of healthy people. A cross sectional study was conducted on a population of healthy young adults. Twenty-seven participants performed three trials (n=81 jumps) of squat jump and countermovement jump tests. Acceleration variables were measured through a smartphone's inertial sensor. Additionally, jump variables from a contact mat and lower limbs dynamometry were collected. In the present study, the kinematic variables derived from acceleration through the inertial sensor of a smartphone iPhone 4S, dynamometry of lower limbs with a handheld dynamometer, and the height and flight time with a contact mat have been described in vertical jump tests from a cohort of young healthy subjects. The development of the execution has been described, examined and identified in a squat jump test and countermovement jump test under acceleration variables that were obtained with the smartphone. The built-in iPhone 4S inertial sensor is able to measure acceleration variables while performing vertical jump tests for the squat jump and countermovement jump in healthy young adults. The acceleration

Teens in cars.

NARCIS (Netherlands)

2014-01-01

A study from Safe Kids Worldwide, made possible by a grant from the General Motors Foundation, surveyed 1,000 teens to learn why more teens die in motor vehicle crashes than from any other cause of death. The report highlights why teens don’t always buckle up, explores their texting and distraction

The Relationship Between the Lower-Body Muscular Profile and Swimming Start Performance

Directory of Open Access Journals (Sweden)

García-Ramos Amador

2016-04-01

Full Text Available This study aimed to examine the correlation of different dry land strength and power tests with swimming start performance. Twenty international level female swimmers (age 15.3 ± 1.6 years, FINA point score 709.6 ± 71.1 performed the track freestyle start. Additionally, dry land tests were conducted: a squat (SJ and countermovement jumps (CMJ, b squat jumps with additional resistance equivalent to 25, 50, 75 and 100% of swimmers’ body weight [BW], and c leg extension and leg flexion maximal voluntary isometric contractions. Correlations between dry land tests and start times at 5, 10 and 15 m were quantified through Pearson’s linear correlation coefficients (r. The peak bar velocity reached during the jumps with additional resistance was the variable most correlated to swimming start performance (r = -0.57 to -0.66 at 25%BW; r = -0.57 to -0.72 at 50%BW; r = -0.59 to -0.68 at 75%BW; r = -0.50 to - 0.64 at 100%BW. A few significant correlations between the parameters of the SJ and the CMJ with times of 5 and 10 m were found, and none with the isometric variables. The peak velocity reached during jumps with external loads relative to BW was found a good indicator of swimming start performance.

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

Energy Technology Data Exchange (ETDEWEB)

Lauritzen, D V; Jordan, L K; Gordon, M S [Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095-1606 (United States); Hertel, F S, E-mail: dlauritz@ccsf.ed, E-mail: fritz.hertel@csun.ed, E-mail: msgordon@ucla.ed, E-mail: ljordan@ucla.ed [Department of Biology, California State University-Northridge, Northridge, CA 91330 (United States)

2010-09-15

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Implementation evaluation of steering teens safe: engaging parents to deliver a new parent-based teen driving intervention to their teens.

Science.gov (United States)

Ramirez, Marizen; Yang, Jingzhen; Young, Tracy; Roth, Lisa; Garinger, Anne; Snetselaar, Linda; Peek-Asa, Corinne

2013-08-01

Parents play a fundamental role in teaching their children safe driving skills to reduce risk of motor vehicle crashes, the leading cause of death for teens. Steering Teens Safe is a new parent-based intervention that equips parents with communication skills to talk about, demonstrate, and practice safe driving behaviors and skills with their teens. This implementation evaluation focuses on a sample of 83 parents who delivered Steering Teens Safe to their teens. One-, 2- and 3-month follow-up assessments were conducted with intervention parents to evaluate the self-reported quantity and quality of talking about, demonstrating, and practicing safe driving goals with teens; perceived success and benefit of the program; and barriers to implementation. Over 3 months of follow-up, parents discussed driving goals with their teens for a median of 101.5 minutes. The most frequently addressed topics were general safety principles, including distracted driving, driving in bad weather, wearing a seat belt, and being a safe passenger. Parents spent a median of 30 minutes practicing safe driving skills such as changing lanes. Sixty-seven percent of parents talked to their children about rural road safety, but just 36% demonstrated and half practiced these skills with their teens. Barriers to implementation include time and opportunity barriers and resistant attitudes of their teens. However, barriers neither affected frequency of engagement nor parents' perceived benefit and comfort in delivering the program. Parents with time/opportunity barriers also had higher practice and demonstration times than parents without these barriers. Findings indicate high acceptability among parent implementers and promise for real-world delivery. Future studies are needed to assess intervention impact.

Strep Throat (For Teens)

Science.gov (United States)

... Feelings Expert Answers Q&A Movies & More for Teens Teens site Sitio para adolescentes Body Mind Sexual Health ... Educators Search English Español Strep Throat KidsHealth / For Teens / Strep Throat What's in this article? What Is ...

Easy Exercises for Teens

Science.gov (United States)

... Movies & More for Teens Teens site Sitio para adolescentes Body Mind Sexual Health Food & Fitness Diseases & Conditions ... for Teens Print en español Ejercicios fáciles para adolescentes Finding it hard to fit in fitness? Just ...

Teen use of a patient portal: a qualitative study of parent and teen attitudes.

Science.gov (United States)

Bergman, David A; Brown, Nancy L; Wilson, Sandra

2008-01-01

We conducted a qualitative study of the attitudes of teens and parents toward the use of a patient portal. We conducted two teen and two parent focus groups, one teen electronic bulletin board, and one parent electronic bulletin board. Videotapes and transcripts from the groups were independently analyzed by two reviewers for significant themes, which were then validated by two other members of the research team. Twenty-eight teens and 23 parents participated in the groups. Significant themes included issues about teens' control of their own healthcare; enthusiasm about the use of a patient portal to access their providers, seek health information, and make appointments; and concerns about confidentiality. In summary, there was considerable support among teens and parents for a patient portal as well as concerns about confidentiality. The teen portal affords an opportunity to negotiate issues of confidentiality.

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

DEFF Research Database (Denmark)

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

1999-01-01

. The jumps were recorded on highspeed film (500 Hz) combined with registration of ground reaction forces, and net joint moments were calculated by inverse dynamics. The purpose was to investigate the choice of strategy in two standard jumps, squat jump and countermovement jump. The volleyball jump...... was performed with a sequential strategy and the ballet jump was performed with a simultaneous strategy. In the two standard jumps, the choice of strategy was individual and not related to training background. This was additionally confirmed in a test of seven ballet dancers and seven volleyball players....

CDC Vital Signs: Preventing Teen Pregnancy

Science.gov (United States)

... Press Kit Read the MMWR Science Clips Preventing Teen Pregnancy A Key Role for Health Care Providers Language: ... Battles: Teen Pregnancy Prevention Status Reports (PSRs): Teen Pregnancy FastStats: Teen Births Vital Signs – Preventing Teen Pregnancy [PODCAST – 1: ...

Teen Depression

Science.gov (United States)

What is depression in teens? Teen depression is a serious medical illness. It's more than just a feeling of being sad or "blue" for a few days. It is ... trouble focusing and have no motivation or energy. Depression can make you feel like it is hard ...

Teen Mothers' Mental Health.

Science.gov (United States)

SmithBattle, Lee; Freed, Patricia

2016-01-01

Psychological distress is common in teen mothers. High rates of distress are attributed to teen mothers' childhood adversities and the challenges of parenting in the context of chronic stress, cumulative disadvantage, and limited social support. We describe the prevalence of psychological distress in teen mothers; what is known about its origins and impact on mothers and children; factors that promote teen mothers' mental health and resilience; and the many barriers that make it difficult to obtain traditional mental healthcare. We also briefly review the few studies that test interventions to improve teen mothers' mental health. Because barriers to traditional mental health treatment are ubiquitous and difficult to remedy, the second article in this two-part series calls for nurses in healthcare settings, schools, and home visiting programs to screen pregnant and parenting teens for adverse childhood experiences and psychological distress, and to integrate strength-based and trauma-based principles into their practice. Creating a supportive setting where past traumas and psychological distress are addressed with skill and sensitivity builds upon teen mothers' strengths and their aspirations to be the best parents they can be. These approaches facilitate the long-term health and development of mother and child.

Teen Science Cafés: A Model for Addressing Broader Impacts, Diversity, and Recruitment

Science.gov (United States)

Hall, M.; Mayhew, M. A.

2017-12-01

Teen Science Café programs (TeenScienceCafe.org) are a free and fun way for teens to explore science and technology affecting their lives. Through lively presentations, conversation, and activities to explore a topic deeply, Café programs open doors for teens to learn from experts about exciting and rewarding STEM career pathways. The programs are local and led by teens with the help of an adult mentor. The Teen Science Café Network (teensciencecafe.org) provides mentoring and resources, including small grants, to help organizations get started with and then maintain successful "teen café" programs. Through membership in the Network, more than 80 Teen Science Cafés have sprung up across the country, from rural towns to major cities. They serve a critical need for teens - meeting and engaging with STEM professionals, learning about their career paths, and seeing their passion for the work they do. Teen Science Café programs can offer geoscience departments a substantive, yet low cost, way to meet the challenges many of them face: finding ways to increase enrollment, helping faculty satisfy the broader impacts requirements of funding agencies, connecting with the surrounding communities, and providing opportunities for faculty and graduate students to learn how to communicate their science effectively to the public audience. The typical experience of scientists who have presented in teen cafés throughout the Network is that the communication skills learned spill over into their courses, proposals, and presentations to administrators and program officers. A department might partner with one or more organizations in their surrounding communities—libraries, for example—and engage its faculty and its graduate students—and even its undergraduates—in providing geoscience programming across multiple disciplines to local teens. Besides the internal benefits to the department's personnel and the value of establishing connections with community organizations

Smells Like Teen Spirit: Evaluating a Midwestern Teen Court

Science.gov (United States)

Norris, Michael; Twill, Sarah; Kim, Chigon

2011-01-01

Teen courts have grown rapidly in the United States despite little evidence of their effectiveness. A survival analysis of 635 teen court and 186 regular diversion participants showed no significant differences in recidivism, although program completers were half as likely to reoffend as noncompleters. Older offenders survived significantly better…

Risk factors for epistaxis in jump racing in Great Britain (2001-2009).

Science.gov (United States)

Reardon, Richard J M; Boden, Lisa A; Mellor, Dominic J; Love, Sandy; Newton, Richard J; Stirk, Anthony J; Parkin, Timothy D

2015-07-01

The aim of this study was to evaluate risk factors associated with developing epistaxis in jump racing in Great Britain (GB). A retrospective analysis of records from horses running in all hurdle and steeplechase races in GB between 2001 and 2009 identified diagnoses of epistaxis whilst still at the racecourse. Data were used from 603 starts resulting in epistaxis (event) and 169,065 starts resulting in no epistaxis (non-event) in hurdle racing, and from 550 event starts and 102,344 non-event starts in steeplechase racing. Two multivariable logistic regression models to evaluate risk factors associated with epistaxis were produced. The potential effect of clustering of data (within horse, horse dam, horse sire, trainer, jockey, course, race and race meet) on the associations between risk factors and epistaxis was examined using mixed-effects models. Multiple factors associated with increased risk of epistaxis were identified. Those identified in both types of jump racing included running on firmer ground; horses with >75% of career starts in flat racing and a previous episode of epistaxis recorded during racing. Risk factors identified only in hurdle racing included racing in the spring and increased age at first race; and those identified only in steeplechase racing included running in a claiming race and more starts in the previous 3-6 months. The risk factors identified provide important information about the risk of developing epistaxis. Multiple avenues for further investigation are highlighted, including unmeasured variables at the level of the racecourse. The results of this study can be used to guide the development of interventions to minimise the risk of epistaxis in jump racing. Copyright © 2015. Published by Elsevier Ltd.

Jumping Dynamics

DEFF Research Database (Denmark)

Sannino, Francesco

2013-01-01

paradigm the physical scale and henceforth also the massive spectrum of the theory jump at the lower boundary of the conformal window. In particular we propose that a theory can suddenly jump from a Quantum Chromodynamics type spectrum, at the lower boundary of the conformal window, to a conformal one...... without particle interpretation. The jumping scenario, therefore, does not support a near-conformal dynamics of walking type. We will also discuss the impact of jumping dynamics on the construction of models of dynamical electroweak symmetry breaking....

An Update on Teen Pregnancy.

Science.gov (United States)

Ahern, Nancy R; Bramlett, Traci

2016-02-01

After years of high teen birth rates, there is currently a decline in U.S. pregnancy and birth rates among teens. Nevertheless, these rates continue to be higher than those of most global counterparts, and psychosocial and physical adversities still occur for pregnant teens and their children. The declining birth rates may be due to teens making better choices about contraceptive use and sexual behaviors. Psychiatric-mental health nurses are in key positions to enhance pregnancy prevention for teens. [Journal of Psychosocial Nursing and Mental Health Services, 54(2), 25-28.]. Copyright 2016, SLACK Incorporated.

Drop Jumping as a Training Method for Jumping Ability

NARCIS (Netherlands)

Bobbert, Maarten F.

1990-01-01

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

Steering teens safe: a randomized trial of a parent-based intervention to improve safe teen driving.

Science.gov (United States)

Peek-Asa, Corinne; Cavanaugh, Joseph E; Yang, Jingzhen; Chande, Vidya; Young, Tracy; Ramirez, Marizen

2014-07-31

Crashes are the leading cause of death for teens, and parent-based interventions are a promising approach. We assess the effectiveness of Steering Teens Safe, a parent-focused program to increase safe teen driving. Steering Teens Safe aimed to improve parental communication with teens about safe driving using motivational interviewing techniques in conjunction with 19 safe driving lessons. A randomized controlled trial involved 145 parent-teen dyads (70 intervention and 75 control). Intervention parents received a 45-minute session to learn the program with four follow-up phone sessions, a DVD, and a workbook. Control parents received a standard brochure about safe driving. Scores were developed to measure teen-reported quantity and quality of parental communication about safe driving. The main outcome measure was a previously validated Risky Driving Score reported by teens. Because the Score was highly skewed, a generalized linear model based on a gamma distribution was used for analysis. Intervention teens ranked their parent's success in talking about driving safety higher than control teens (p = 0.035) and reported that their parents talked about more topics (non-significant difference). The Risky Driving Score was 21% lower in intervention compared to control teens (85% CI = 0.60, 1.00). Interaction between communication quantity and the intervention was examined. Intervention teens who reported more successful communication had a 42% lower Risky Driving Score (95% CI = 0.37, 0.94) than control parents with less successful communication. This program had a positive although not strong effect, and it may hold the most promise in partnership with other programs, such as Driver's Education or Graduated Driver's License policies. ClinicalTrials.gov NCT01014923. Registered Nov. 16, 2009.

Anemia (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Anemia KidsHealth / For Teens / Anemia What's in this article? ... Enough Iron Print en español Anemia What Is Anemia? Lots of teens are tired. With all the ...

Types of Cancer Teens Get

Science.gov (United States)

... Movies & More for Teens Teens site Sitio para adolescentes Body Mind Sexual Health Food & Fitness Diseases & Conditions ... en español Tipos de cáncer que padecen los adolescentes Cancer is rare in teens. Certain diseases like ...

Promoting Teen Mothers' Mental Health.

Science.gov (United States)

Freed, Patricia; SmithBattle, Lee

2016-01-01

In this second article in a two-part series, we call for the integration of strengths-based and trauma-informed care into services for teen mothers. Nurses working with teen mothers in health clinics, schools and home visiting programs can play a pivotal role in promoting their mental health. Many teen mothers have high levels of psychological distress and histories of adverse experiences that cannot be ignored, and cannot solely be addressed by referral to mental health services. Nurses must be prepared to assess for trauma and be open to listening to teen mothers' experiences. Principles of strengths-based and trauma-informed care are complementary and can be integrated in clinical services so that teen mothers' distress is addressed and their strengths and aspirations are supported. Potential screening tools, interviewing skills and basic strategies to alleviate teen mothers' distress are discussed.

Attitudes toward teen mothers among nursing students and psychometric evaluation of Positivity Toward Teen Mothers scale.

Science.gov (United States)

Kim, Son Chae; Burke, Leanne; Sloan, Chris; Barnett, Shannon

2013-09-01

To prepare future nurses who can deliver high quality nursing care to teen mothers, a better understanding of the nursing students' perception of teen mothers is needed. A descriptive cross-sectional study was conducted among 228 nursing students to evaluate the psychometric properties of the Positivity Toward Teen Mothers (PTTM) scale, to explore nursing students' general empathy and attitudes toward teen mothers, and to investigate the predictors of nursing students' attitudes toward teen mothers. Principal component factor analysis with varimax rotation resulted in a 19-item PTTM-Revised scale with Non-judgmental and Supportive subscales. Cronbach's alphas for the subscales were 0.84 and 0.69, respectively, and 0.87 for the total scale. Simultaneous multiple regression models showed that general empathy and having a teen mother in the family or as an acquaintance were significant predictors of positive attitudes toward teen mothers, whereas age was a significant negative predictor. The PTTM-Revised scale is a promising instrument for assessing attitudes toward teen mothers. Copyright © 2012 Elsevier Ltd. All rights reserved.

Jump locations of jump-diffusion processes with state-dependent rates

International Nuclear Information System (INIS)

Miles, Christopher E; Keener, James P

2017-01-01

We propose a general framework for studying statistics of jump-diffusion systems driven by both Brownian noise (diffusion) and a jump process with state-dependent intensity. Of particular natural interest in many physical systems are the jump locations: the system evaluated at the jump times. As an example, this could be the voltage at which a neuron fires, or the so-called ‘threshold voltage’. However, the state-dependence of the jump rate provides direct coupling between the diffusion and jump components, making it difficult to disentangle the two to study individually. In this work, we provide an iterative map formulation of the sequence of distributions of jump locations. The distributions computed by this map can be used to elucidate other interesting quantities about the process, including statistics of the interjump times. Ultimately, the limit of the map reveals that knowledge of the stationary distribution of the full process is sufficient to recover (but not necessarily equal to) the distribution of jump locations. We propose two biophysical examples to illustrate the use of this framework to provide insight about a system. We find that a sharp threshold voltage emerges robustly in a simple stochastic integrate-and-fire neuronal model. The interplay between the two sources of noise is also investigated in a stepping model of molecular motor in intracellular transport pulling a diffusive cargo. (paper)

Helping Teens Resist Sexual Pressure

Science.gov (United States)

... Listen Español Text Size Email Print Share Helping Teens Resist Sexual Pressure Page Content Article Body Teens are more ... younger the first time they had intercourse. Helping Teens Resist Sexual Pressure “The pressure on teenagers to have sex ...

A Correction Equation for Jump Height Measured Using the Just Jump System.

Science.gov (United States)

McMahon, John J; Jones, Paul A; Comfort, Paul

2016-05-01

To determine the concurrent validity and reliability of the popular Just Jump system (JJS) for determining jump height and, if necessary, provide a correction equation for future reference. Eighteen male college athletes performed 3 bilateral countermovement jumps (CMJs) on 2 JJSs (alternative method) that were placed on top of a force platform (criterion method). Two JJSs were used to establish consistency between systems. Jump height was calculated from flight time obtained from the JJS and force platform. Intraclass correlation coefficients (ICCs) demonstrated excellent within-session reliability of the CMJ height measurement derived from both the JJS (ICC = .96, P jump height (0.46 ± 0.09 m vs 0.33 ± 0.08 m) than the force platform (P jump height = (0.8747 × alternative jump height) - 0.0666. The JJS provides a reliable but overestimated measure of jump height. It is suggested, therefore, that practitioners who use the JJS as part of future work apply the correction equation presented in this study to resultant jump-height values.

Risk, Jumps, and Diversification

DEFF Research Database (Denmark)

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

We test for price discontinuities, or jumps, in a panel of high-frequency intraday returns for forty large-cap stocks and an equiweighted index from these same stocks. Jumps are naturally classified into two types: common and idiosyncratic. Common jumps affect all stocks, albeit to varying degrees......, while idiosyncratic jumps are stock-specific. Despite the fact that each of the stocks has a of about unity with respect to the index, common jumps are virtually never detected in the individual stocks. This is truly puzzling, as an index can jump only if one or more of its components jump. To resolve...... this puzzle, we propose a new test for cojumps. Using this new test we find strong evidence for many modest-sized common jumps that simply pass through the standard jump detection statistic, while they appear highly significant in the cross section based on the new cojump identification scheme. Our results...

Choose Health Action Teens: A Review of a Teens as Teachers Nutritional Education Training Curriculum

Directory of Open Access Journals (Sweden)

Jeffrey M. Flesch

2016-12-01

Full Text Available This review draws from published research related to the best practices for the utilization of teens as teachers to examine Choose Health Action Teens (CHAT, a teen’s as teachers (TAT training curriculum.  Research shows that there are various components necessary to build a high quality TAT program.  Most of these components fall under four areas in which training is necessary for teens and adults: Teaching strategies, youth/child development, subject matter to be taught, and youth-adult partnerships.  These four areas provide a framework to review the Choose Health Action Teens (CHAT (Crosiar & Wolfe, 2013 teens as teachers training program curriculum.

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

Science.gov (United States)

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

2016-01-01

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

College Students' Positivity toward Teen Mothers

Science.gov (United States)

Eshbaugh, Elaine M.

2011-01-01

Although teen pregnancy and parenthood are more visible in society than in the past, teen mothers are often stereotyped and stigmatized. The study examined positivity toward teen mothers among college students (N = 316) at a midwestern university. Although students responded positively to some items regarding teen mothers, other statements showed…

Control Improvement for Jump-Diffusion Processes with Applications to Finance

International Nuclear Information System (INIS)

Bäuerle, Nicole; Rieder, Ulrich

2012-01-01

We consider stochastic control problems with jump-diffusion processes and formulate an algorithm which produces, starting from a given admissible control π, a new control with a better value. If no improvement is possible, then π is optimal. Such an algorithm is well-known for discrete-time Markov Decision Problems under the name Howard’s policy improvement algorithm. The idea can be traced back to Bellman. Here we show with the help of martingale techniques that such an algorithm can also be formulated for stochastic control problems with jump-diffusion processes. As an application we derive some interesting results in financial portfolio optimization.

Teen pregnancy prevention: current perspectives.

Science.gov (United States)

Lavin, Claudia; Cox, Joanne E

2012-08-01

Teen pregnancy has been subject of public concern for many years. In the United States, despite nearly 2 decades of declining teen pregnancy and birth rates, the problem persists, with significant disparities present across racial groups and in state-specific rates. This review examines recent trends, pregnancy prevention initiatives and family planning policies that address the special needs of vulnerable youth. Unintended teen pregnancies impose potentially serious social and health burdens on teen parents and their children, as well as costs to society. Trends in teen pregnancy and birth rates show continued decline, but state and racial disparities have widened. Demographic factors and policy changes have contributed to these disparities. Research supports comprehensive pregnancy prevention initiatives that are multifaceted and promote consistent and correct use of effective methods of contraception for youth at risk of becoming pregnant. There is strong consensus that effective teen pregnancy prevention strategies should be multifaceted, focusing on delay of sexual activity especially in younger teens while promoting consistent and correct use of effective methods of contraception for those youth who are or plan to be sexually active. There is a need for further research to identify effective interventions for vulnerable populations.

Why is countermovement jump height greater than squat jump height?

NARCIS (Netherlands)

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

1996-01-01

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

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

Science.gov (United States)

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

2016-03-01

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

Teen Ambassador Leadership Kit (TALK

Directory of Open Access Journals (Sweden)

Donna R. Gillespie

2012-12-01

Full Text Available Teen Ambassador Leadership Kit, (TALK, is an annual weekend retreat designed for teens interested in promoting and marketing 4-H in their communities. TALK organizers felt teens would benefit from an intensive weekend retreat focused on communication. TALK produces a network of educated and excited 4-H teens that are available to help with 4-H promotion and marketing. Participants arrive on Friday evening for team building activities, on Saturday they participate in one of the workshops offered and on Sunday morning each workshop group has the opportunity to share their completed projects and what they learned. At the conclusion of the retreat, teens are designated "County 4-H Ambassadors" and certificates of completion, professional business cards and polo shirts are presented. The TALK teen participants return home to share what they learned with their local county 4-H staff and help promote and market 4-H in their communities.

Advanced driver assistance systems for teen drivers: Teen and parent impressions, perceived need, and intervention preferences.

Science.gov (United States)

Weiss, Eve; Fisher Thiel, Megan; Sultana, Nahida; Hannan, Chloe; Seacrist, Thomas

2018-02-28

From the advent of airbags to electronic stability control, technological advances introduced into automobile design have significantly reduced injury and death from motor vehicle crashes. These advances are especially pertinent among teen drivers, a population whose leading cause of death is motor vehicle crashes. Recently developed advanced driver assistance systems (ADAS) have the potential to compensate for skill deficits and reduce overall crash risk. Yet, ADAS is only effective if drivers are willing to use it. Limited research has been conducted on the suitability of ADAS for teen drivers. The goal of this study is to identify teen drivers' perceived need for ADAS, receptiveness to in-vehicle technology, and intervention preferences. The long-term goal is to understand public perceptions and barriers to ADAS use and to help determine how these systems must evolve to meet the needs of the riskiest driving populations. Three focus groups (N = 24) were conducted with licensed teen drivers aged 16-19 years and 2 focus groups with parents of teen drivers (N = 12). Discussion topics included views on how ADAS might influence driving skills and behaviors; trust in technology; and data privacy. Discussions were transcribed; the team used conventional content analysis and open coding methods to identify 12 coding domains and code transcripts with NVivo 10. Interrater reliability testing showed moderate to high kappa scores. Overall, participants recognized potential benefits of ADAS, including improved safety and crash reduction. Teens suggested that ADAS is still developing and therefore has potential to malfunction. Many teens reported a greater trust in their own driving ability over vehicle technology. They expressed that novice drivers should learn to drive on non-ADAS-equipped cars and that ADAS should be considered a supplemental aid. Many teens felt that overreliance on ADAS may increase distracted driving or risky behaviors among teens. Parents also

Teening chick lit?

OpenAIRE

Whelehan, Imelda, 1960-

2009-01-01

online article - free to access This essay concerns itself with two examples of contemporary teen romance and examines the similarities with adult chick lit. These texts are compared with Judy Blume's classic 'Forever' written in 1975 to emphasis continuities between contemporary teen fiction and its more overty feminist forebears

Teen motherhood and long-term health consequences.

Science.gov (United States)

Patel, Payal H; Sen, Bisakha

2012-07-01

The objective of this article is to examine the association of teen motherhood and long-term physical and mental health outcomes. The physical and mental health components (PCS and MCS) of the SF-12 Healthy Survey in the NLSY79 health module were used to assess long-term health outcomes of women who experienced teenage motherhood. Various familial, demographic, and environmental characteristics were indentified and controlled for that may have predicted teen motherhood and long-term health outcomes. The two comparison groups for teen mothers were women who experienced teen-pregnancy only and women who were engaged in unprotected sexual activity as a teenage but did not experience pregnancy. Multivariate ordinary least squares regression was used for analysis. The average PCS and MCS for teen mothers was 49.91 and 50.89, respectively. Teen mothers exhibited poorer physical health later in life compared to all women as well as the comparison groups. When controlling for age, teen mothers had significantly lower PCS and MCS scores compared to all other women. Furthermore, when controlling for familial, demographic, and environmental characteristics, teen mothers exhibited significantly lower PCS and MCS scores. When comparing teen mothers to the two comparison groups, PCS was not statistically different although MCS was significantly lower in the teen-pregnancy group. Teen motherhood does lead to poorer physical health outcomes later in life. On the other hand, poorer mental health outcomes in later life may be attributed to the unmeasured factors leading to a teen pregnancy and not teen motherhood itself. Additional research needs to be conducted on the long-term consequences of teen motherhood.

Teen Use of a Patient Portal: A Qualitative Study of Parent and Teen Attitudes

OpenAIRE

Bergman, David A.; Brown, Nancy L.; Wilson, Sandra

2008-01-01

We conducted a qualitative study of the attitudes of teens and parents toward the use of a patient portal. We conducted two teen and two parent focus groups, one teen electronic bulletin board, and one parent electronic bulletin board. Videotapes and transcripts from the groups were independently analyzed by two reviewers for significant themes, which were then validated by two other members ...

Eleven Tribes Jump START Clean Energy Projects, Summer 2012 (Newsletter)

Energy Technology Data Exchange (ETDEWEB)

2012-06-01

This newsletter describes key activities of the DOE Office of Indian Energy Policy and Programs for Summer 2012. The U.S. Department of Energy Office of Indian Energy Policy and Programs (DOE-IE) has selected 11 Tribes - five in Alaska and six in the contiguous United States - to receive on-the-ground technical support for community-based energy efficiency and renewable energy projects as part of DOE-IE's Strategic Technical Assistance Response Team (START) Program. START finalists were selected based on the clarity of their requests for technical assistance and the ability of START to successfully work with their projects or community. Technical experts from DOE and its National Renewable Energy Laboratory (NREL) will work directly with community-based project teams to analyze local energy issues and assist the Tribes in moving their projects forward. In Alaska, the effort will be bolstered by DOE-IE's partnership with the Denali Commission, which will provide additional assistance and expertise, as well as funding to fuel the Alaska START initiative.

Educational Resiliency in Teen Mothers

Science.gov (United States)

Watson, Linnea Lynne; Vogel, Linda R.

2017-01-01

While recent research has shown the long-term effects of teen pregnancy are not as devastating as once predicted, more than 40 years after the passage of Title IX legislation mandating equal educational opportunities for pregnant and parenting teens, only 50% of teen parents graduate high school, lagging far behind their non-parenting peers. This…

Help Teens Manage Diabetes

Science.gov (United States)

Skip Navigation Bar Home Current Issue Past Issues Help Teens Manage Diabetes Past Issues / Spring 2008 Table ... healthy behaviors, and conflict resolution. The CST training helps diabetic teens to make good decisions when it ...

Teen Suicide and Guns

Science.gov (United States)

... Issues Listen Text Size Email Print Share Teen Suicide and Guns Page Content Article Body Protect Your ... of a passing problem, not the outcome! Teen Suicide—A Big Problem Suicide is one of the ...

Young adult outcomes of children born to teen mothers: effects of being born during their teen or later years.

Science.gov (United States)

Lipman, Ellen L; Georgiades, Katholiki; Boyle, Michael H

2011-03-01

Children of teen mothers exhibit adverse outcomes through adolescence. It is unclear whether these adverse outcomes extend to adulthood and apply to all of her children, or only those born when she was a teen. We examine the associations between young adult functioning and being born to a teen mother aged ≤20 years at the time of birth (current teen), and being born to a teen mother later in her life (>21 years, prior teen). The 1983 Ontario Child Health Study (OCHS) and 2001 follow-up are used, including 2,355 participants 4 to 16 years old in 1983 with 2001 data. Using multilevel modeling we assessed the association between being born to a current versus prior teen mother, relative to a nonteen mother, and 2001 outcomes, controlling for individual and family level characteristics assessed in childhood. Being born to a teen mother (versus a nonteen mother) is associated with poorer educational achievement, life satisfaction, and personal income. Accounting for time of sample children's birth in teen mothers' lives, individuals born to current and prior teen mothers showed a ~0.8-year educational deficit, relative to individuals born to nonteen mothers in fully adjusted models. Individuals born to current teen mothers reported lower life satisfaction and personal income (-$7,262). There were no significant group differences at follow-up in mental or physical health between individuals born to nonteen mothers and those born to current or prior teen mothers. Although being born to a teen mother exerts a pervasive adverse effect on educational attainment, the adverse effects on life satisfaction and personal income appear to be selective for individuals born to a current teen mother. Further research is required to understand these differential effects. Copyright © 2011 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Psychophysiological response in parachute jumps, the effect of experience and type of jump.

Science.gov (United States)

Clemente-Suárez, Vicente Javier; Robles-Pérez, José Juan; Fernández-Lucas, Jesús

2017-10-01

We aimed to analyse the effect of experience and type of parachute jump on the psychophysiological responses of jumpers. We analysed blood oxygen saturation, heart rate, blood glucose, lactate and creatinkinase, leg strength, isometric hand strength, cortical arousal, specific fine motor skills, self-confidence and cognition, and somatic and state anxiety, before and after four different parachute jumps: a sport parachute jump, a manual tactical parachute jump, tandem pilots, and tandem passengers. Independently of the parachute jump, the psychophysiological responses of experienced paratroopers were not affected by the jumps, except for an increase in anaerobic metabolism. Novice parachute jumpers presented a higher psychophysiological stress response than the experienced jumpers, together with a large anticipatory anxiety response before the jump; however, this decreased after the jump, although the high physiological activation was maintained. This information could be used by civil and military paratroopers' instructors to improve their training programmes. Copyright © 2017 Elsevier Inc. All rights reserved.

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

Science.gov (United States)

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

2011-01-01

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

Jumping in Arithmetic

NARCIS (Netherlands)

Visser, Albert

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

Jumping in Arithmetic

NARCIS (Netherlands)

Visser, Albert

2014-01-01

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

PeoplePersonality: Chris Clarke - a physicist who studies ice cream Teaching Anecdotes: Annie Jump Cannon Obituary: György Marx 1927-2002 Starting Out: What Katie did next: part 3 Opinions: What is really important?

Science.gov (United States)

2003-03-01

Featuring relationships, personalities, interactions, environments and reputations involved in physics and education PERSONALITY (156) Chris Clarke - a physicist who studies ice cream TEACHING ANECDOTES (157) Annie Jump Cannon OBITUARY (158) György Marx 1927-2002 Steven Chapman STARTING OUT (159) What Katie did next: part 3 Katie Pennicott OPINIONS (160) What is really important? Kerry Parker

Adolescent pregnancy. Teen perspectives on prevention.

Science.gov (United States)

Aquilino, M L; Bragadottir, H

2000-01-01

To elicit the views of teens concerning effective strategies to prevent pregnancy. Qualitative methods and a focus group approach were used. The sample consisted of male and female adolescents, 14 to 19 years of age, in grades 9 to 12, who volunteered to participate in the study. Seven groups of teens met with the investigator twice over 2 consecutive weeks. Instruments included a Screening Questionnaire and Focus Group Discussion Guidelines. Teens were concerned about teen pregnancy, and supported a comprehensive approach to sex education beginning in the early elementary grades, with age and developmentally appropriate content and reinforcement from late grade school through high school. Generally, teens thought that teaching abstinence in grade school followed by contraception education in junior high and high school was a realistic strategy for pregnancy prevention. They wanted to discuss sexual feelings as well as the mechanical aspects of sex. Finally, they did not want to be told not to have sex, but rather wanted to be guided in their own decision making. Teens wanted parents and other adults to be involved in helping them understand sexuality and make decisions about sexual behavior. Nurses who work with families need to understand why teens are becoming pregnant, provide opportunities for teens to discuss sexual behavior, and educate parents on sexual development and parent-child communication. Nurses also need to let parents and teens know that they are a resource for information, guidance, and health services related to sexual development and behavior.

Safe driving for teens

Science.gov (United States)

Driving and teenagers; Teens and safe driving; Automobile safety - teenage drivers ... months before taking friends as passengers. Teenage-related driving deaths occur more often in certain conditions. OTHER SAFETY TIPS FOR TEENS Reckless driving is still a ...

The reliability of vertical jump tests between the Vertec and My Jump phone application.

Science.gov (United States)

Yingling, Vanessa R; Castro, Dimitri A; Duong, Justin T; Malpartida, Fiorella J; Usher, Justin R; O, Jenny

2018-01-01

The vertical jump is used to estimate sports performance capabilities and physical fitness in children, elderly, non-athletic and injured individuals. Different jump techniques and measurement tools are available to assess vertical jump height and peak power; however, their use is limited by access to laboratory settings, excessive cost and/or time constraints thus making these tools oftentimes unsuitable for field assessment. A popular field test uses the Vertec and the Sargent vertical jump with countermovement; however, new low cost, easy to use tools are becoming available, including the My Jump iOS mobile application (app). The purpose of this study was to assess the reliability of the My Jump relative to values obtained by the Vertec for the Sargent stand and reach vertical jump (VJ) test. One hundred and thirty-five healthy participants aged 18-39 years (94 males, 41 females) completed three maximal Sargent VJ with countermovement that were simultaneously measured using the Vertec and the My Jump . Jump heights were quantified for each jump and peak power was calculated using the Sayers equation. Four separate ICC estimates and their 95% confidence intervals were used to assess reliability. Two analyses (with jump height and calculated peak power as the dependent variables, respectively) were based on a single rater, consistency, two-way mixed-effects model, while two others (with jump height and calculated peak power as the dependent variables, respectively) were based on a single rater, absolute agreement, two-way mixed-effects model. Moderate to excellent reliability relative to the degree of consistency between the Vertec and My Jump values was found for jump height (ICC = 0.813; 95% CI [0.747-0.863]) and calculated peak power (ICC = 0.926; 95% CI [0.897-0.947]). However, poor to good reliability relative to absolute agreement for VJ height (ICC = 0.665; 95% CI [0.050-0.859]) and poor to excellent reliability relative to absolute agreement for peak power

Taking a Teen Pregnancy Prevention Program to the Home: The AIM 4 Teen Moms Experience, Implementation Report

OpenAIRE

Subuhi Asheer; Ellen Kisker

2014-01-01

This report discusses findings from the first 18 months of a program implementation evaluation of AIM 4 Teen Moms, a teen pregnancy intervention designed to delay rapid repeat pregnancies among parenting teen mothers in Los Angeles.

The beginning of time observed in quantum jumps

Energy Technology Data Exchange (ETDEWEB)

Bohm, Arno [CCQS, Physics Department, University of Texas, Austin, TX (United States); Bryant, Peter W. [IBM Research, Rio de Janeiro (Brazil); Uncu, Haydar [Department of Physics, Adnan Menderes University, Aydin (Turkey); Wickramasekara, Sujeev [Department of Physics, Grinnell College, Grinnell, IA (United States); Schleich, Wolfgang P. [Institut fuer Quantenphysik and Center for Integrated Quantum Science and Technology, Universitaet Ulm (Germany); Hagler Institute for Advanced Study, Texas A and M University, College Station, TX (United States); Texas A and M AgriLife, Institute for Quantum Science and Engineering (IQSE) and Department of Physics and Astronomy, Texas A and M University, College Station, TX (United States)

2017-06-15

The phenomenon of quantum jumps observed in a single ion stored in a trap brings to light intimate connections between three different concepts of quantum physics: (i) quantum state trajectories, (ii) Gamow states, and (iii) the arrow of time. In particular, it allows us to identify the starting time of the semigroup time evolution. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Bundles of Norms About Teen Sex and Pregnancy.

Science.gov (United States)

Mollborn, Stefanie; Sennott, Christie

2015-09-01

Teen pregnancy is a cultural battleground in struggles over morality, education, and family. At its heart are norms about teen sex, contraception, pregnancy, and abortion. Analyzing 57 interviews with college students, we found that "bundles" of related norms shaped the messages teens hear. Teens did not think their communities encouraged teen sex or pregnancy, but normative messages differed greatly, with either moral or practical rationalizations. Teens readily identified multiple norms intended to regulate teen sex, contraception, abortion, childbearing, and the sanctioning of teen parents. Beyond influencing teens' behavior, norms shaped teenagers' public portrayals and post hoc justifications of their behavior. Although norm bundles are complex to measure, participants could summarize them succinctly. These bundles and their conflicting behavioral prescriptions create space for human agency in negotiating normative pressures. The norm bundles concept has implications for teen pregnancy prevention policies and can help revitalize social norms for understanding health behaviors. © The Author(s) 2014.

Vital Signs-Preventing Pregnancy in Younger Teens

Centers for Disease Control (CDC) Podcasts

This podcast is based on the April 2014 CDC Vital Signs report. Births to teens are declining, still, in 2012, more than 86,000 teens ages 15 to 17 gave birth. This program discusses what health care providers, parents, and teens can do to help prevent teen pregnancy.

TeenDrivingPlan effectiveness: the effect of quantity and diversity of supervised practice on teens' driving performance.

Science.gov (United States)

Mirman, Jessica H; Albert, W Dustin; Curry, Allison E; Winston, Flaura K; Fisher Thiel, Megan C; Durbin, Dennis R

2014-11-01

The large contribution of inexperience to the high crash rate of newly licensed teens suggests that they enter licensure with insufficient skills. In a prior analysis, we found moderate support for a direct effect of a web-based intervention, the TeenDrivingPlan (TDP), on teens' driving performance. The purpose of the present study was to identify the mechanisms by which TDP may be effective and to extend our understanding of how teens learn to drive. A randomized controlled trial conducted with teen permit holders and parent supervisors (N = 151 dyads) was used to determine if the effect of TDP on driver performance operated through five hypothesized mediators: (1) parent-perceived social support; (2) teen-perceived social support; (3) parent engagement; (4) practice quantity; and (5) practice diversity. Certified driving evaluators, blinded to teens' treatment allocation, assessed teens' driving performance 24 weeks after enrollment. Mediator variables were assessed on self-report surveys administered periodically over the study period. Exposure to TDP increased teen-perceived social support, parent engagement, and practice diversity. Both greater practice quantity and diversity were associated with better driving performance, but only practice diversity mediated the relationship between TDP and driver performance. Practice diversity is feasible to change and increases teens' likelihood of completing a rigorous on-road driving assessment just before licensure. Future research should continue to identify mechanisms that diversify practice driving, explore complementary ways to help families optimize the time they spend on practice driving, and evaluate the long-term effectiveness of TDP. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Teen online problem solving for teens with traumatic brain injury: Rationale, methods, and preliminary feasibility of a teen only intervention.

Science.gov (United States)

Wade, Shari L; Narad, Megan E; Kingery, Kathleen M; Taylor, H Gerry; Stancin, Terry; Kirkwood, Michael W; Yeates, Keith O

2017-08-01

To describe the Teen Online Problem Solving-Teen Only (TOPS-TO) intervention relative to the original Teen Online Problem Solving-Family (TOPS-F) intervention, to describe a randomized controlled trial to assess intervention efficacy, and to report feasibility and acceptability of the TOPS-TO intervention. Research method and design: This is a multisite randomized controlled trial, including 152 teens (49 TOPS-F, 51 TOPS-TO, 52 IRC) between the ages of 11-18 who were hospitalized for a moderate to severe traumatic brain injury in the previous 18 months. Assessments were completed at baseline, 6-months post baseline, and 12-months post baseline. Data discussed include adherence and satisfaction data collected at the 6-month assessment (treatment completion) for TOPS-F and TOPS-TO. Adherence measures (sessions completed, dropout rates, duration of treatment engagement, and rates of program completion) were similar across treatment groups. Overall, teen and parent reported satisfaction was high and similar across groups. Teens spent a similar amount of time on the TOPS website across groups, and parents in the TOPS-F spent more time on the TOPS website than those in the TOPS-TO group (p = .002). Parents in the TOPS-F group rated the TOPS website as more helpful than those in the TOPS-TO group (p = .05). TOPS-TO intervention is a feasible and acceptable intervention approach. Parents may perceive greater benefit from the family based intervention. Further examination is required to understand the comparative efficacy in improving child and family outcomes, and who is likely to benefit from each approach. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The ripples of adolescent motherhood: social, educational, and medical outcomes for children of teen and prior teen mothers.

Science.gov (United States)

Jutte, Douglas P; Roos, Noralou P; Brownell, Marni D; Briggs, Gemma; MacWilliam, Leonard; Roos, Leslie L

2010-01-01

We examined medical, educational and social risks to children of teen mothers and children of nonadolescent mothers with a history of teen birth (prior teen mothers) and considered these risks at both the individual and societal level. A population-based, retrospective cohort study tracked outcomes through young adulthood for children born in Manitoba, Canada (n = 32 179). chi(2) and logistic regression analyses examined risk of childhood death or hospitalization, failure to graduate high school, intervention by child protective services, becoming a teen mother, and welfare receipt as a young adult. For children of both teen and prior teen mothers, adjusted likelihoods of death during infancy, school-aged years, and adolescence were more than 2-fold higher than for other children. Risks for hospitalization, high hospital use, academic failure, and poor social outcomes were also substantially higher. At a societal level, only 16.5% of cohort children were born to teen and prior teen mothers. However, these children accounted for 27% of first-year hospitalizations, 34% of deaths (birth to 17 years), 30% of failures to graduate high school, 51% in foster care, 44% on welfare as young adults, and 56% of next-generation young teen mothers. Children of prior teen mothers had increased risks for poor health and for educational and social outcomes nearly equal to those seen in children of teen mothers. Combined, these relatively few children experienced a large share of the negative outcomes occurring among young people. Our results suggest the need to expand the definition of risk associated with adolescent motherhood and target their children for enhanced medical and social services. Copyright 2010 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Preventing Pregnancy in Younger Teens PSA (:60)

Centers for Disease Control (CDC) Podcasts

This 60 second public service announcement is based on the April 2014 CDC Vital Signs report. Births to teens are declining, still, more than 305,000 teens ages 15 to 19 gave birth. This program discusses what health care providers, parents, and teens can do to help prevent teen pregnancy.

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

Science.gov (United States)

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

2010-02-01

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

Intervention improves physician counseling on teen driving safety.

Science.gov (United States)

Campbell, Brendan T; Borrup, Kevin; Saleheen, Hassan; Banco, Leonard; Lapidus, Garry

2009-07-01

As part of a statewide campaign, we surveyed physician attitudes and practice regarding teen driving safety before and after a brief intervention designed to facilitate in office counseling. A 31-item self-administered survey was mailed to Connecticut physicians, and this was followed by a mailing of teen driving safety materials to physician practices in the state. A postintervention survey was mailed 8 months after the presurvey. A total of 102 physicians completed both the pre and postsurveys. Thirty-nine percent (39%) reported having had a teen in their practice die in a motor vehicle crash in the presurvey, compared with 49% in the postsurvey. Physician counseling increased significantly for a number of issues: driving while impaired from 86% to 94%; restrictions on teen driving from 53% to 64%; teen driving laws from 53% to 63%; safe vehicle from 32% to 42%; parents model safe driving from 29% to 44%; and teen-parent written contract from 15% to 37%. At baseline, the majority of physicians who provide care to teenagers in Connecticut report discussing and counseling teens on first wave teen driver safety issues (seat belts, alcohol use), but most do not discuss graduate driver licensing laws or related issues. After a brief intervention, there was a significant increase in physician counseling of teens on teen driving laws and on the use of teen-parent contracts. Additional interventions targeting physician practices can improve physician counseling to teens and their parents on issues of teen driving safety.

Intergenerational teen pregnancy: a population-based cohort study.

Science.gov (United States)

Liu, Ning; Vigod, Simone N; Farrugia, M Michèle; Urquia, Marcelo L; Ray, Joel G

2018-05-22

To estimate the intergenerational association in teenage pregnancy, and whether there is a coupling tendency between a mother and daughter in how their teen pregnancies end, such as an induced abortion (IA) vs. a livebirth. Population-based cohort study. Ontario, Canada. 15,097 mothers and their 16,177 daughters. Generalized estimating equations generated adjusted odds ratios (aOR) of a daughter experiencing a teen pregnancy in relation to the number of teen pregnancies her mother had. Multinomial logistic regression estimated the odds that a teen pregnancy ended with IA among both mother and daughter. All models were adjusted for maternal age and world region of origin, the daughter's socio-demographic characteristics and comorbidities, mother-daughter cohabitation, and neighborhood-level teen pregnancy rate. Teen pregnancy in the daughter, between ages 15-19 years, and also the nature of the daughter's teen pregnancy, categorized as i) no teen pregnancy, ii) at least one teen pregnancy, all exclusively ending with a livebirth, and iii) at least one teen pregnancy, with at least one teen pregnancy ending with an IA. The proportion of daughters having a teen pregnancy among those whose mother had 0, 1, 2, or ≥ 3 teen pregnancies was 16.3%, 24.9%, 33.5% and 36.3%, respectively. The aOR of a daughter having a teen pregnancy was 1.42 (95% CI 1.25-1.61) if her mother had 1, 1.97 (95% CI 1.71-2.26) if she had 2, and 2.17 (95% CI 1.84-2.56) if her mother had ≥ 3 teen pregnancies, relative to none. If a mother had ≥ 1 teen pregnancy ending with IA, then her daughter had an aOR of 2.12 (95% CI 1.76-2.56) for having a teen pregnancy also ending with IA; whereas, if a mother had ≥ 1 teen pregnancy, all ending with a livebirth, then her daughter had an aOR of 1.73 (95% CI 1.46-2.05) for that same outcome. There is a strong intergenerational occurrence of teenage pregnancy between a mother and daughter, including a coupling tendency in how the pregnancy ends. This

Measurements of K shell absorption jump factors and jump ratios using EDXRF technique

Science.gov (United States)

Kacal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

2015-04-01

In the present work, the K-shell absorption jump factors and jump ratios for 30 elements between Ti ( Z = 22) and Er ( Z = 68) were measured by energy dispersive X-ray fluorescence (EDXRF) technique. The jump factors and jump ratios for these elements were determined by measuring the K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to- Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using an Am-241 radioactive point source and a Si (Li) detector in direct excitation and transmission experimental geometry. The results for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.

Teens and Mobile Phones: Text Messaging Explodes as Teens Embrace It as the Centerpiece of Their Communication Strategies with Friends

Science.gov (United States)

Lenhart, Amanda; Ling, Rich; Campbell, Scott; Purcell, Kristen

2010-01-01

Daily text messaging among American teens has shot up in the past 18 months, from 38% of teens texting friends daily in February of 2008 to 54% of teens texting daily in September 2009. And it's not just frequency--teens are sending enormous quantities of text messages a day. Half of teens send 50 or more text messages a day, or 1,500 texts a…

Later Start Time for Teens Improves Grades, Mood, and Safety

Science.gov (United States)

Wahlstrom, Kyla L.

2017-01-01

A recent study by the University of Minnesota looked at eight high schools across the U.S. that chose later start times, from 8:00 a.m. to 8:55 a.m. The study found significant decreases in absences and tardiness as well as greater academic benefits for schools with the latest start times. Among the 9,395 students in the study, those who slept…

Strength Determinants of Jump Height in the Jump Throw Movement in Women Handball Players.

Science.gov (United States)

McGhie, David; Østerås, Sindre; Ettema, Gertjan; Paulsen, Gøran; Sandbakk, Øyvind

2018-06-08

McGhie, D, Østerås, S, Ettema, G, Paulsen, G, and Sandbakk, Ø. Strength determinants of jump height in the jump throw movement in women handball players. J Strength Cond Res XX(X): 000-000, 2018-The purpose of the study was to improve the understanding of the strength demands of a handball-specific jump through examining the associations between jump height in a jump throw jump (JTJ) and measures of lower-body maximum strength and impulse in handball players. For comparison, whether the associations between jump height and strength differed between the JTJ and the customarily used countermovement jump (CMJ) was also examined. Twenty women handball players from a Norwegian top division club participated in the study. Jump height was measured in the JTJ and in unilateral and bilateral CMJ. Lower-body strength (maximum isometric force, one-repetition maximum [1RM], impulse at ∼60% and ∼35% 1RM) was measured in seated leg press. The associations between jump height and strength were assessed with correlation analyses and t-tests of dependent r's were performed to determine if correlations differed between jump tests. Only impulse at ∼35% 1RM correlated significantly with JTJ height (p jump height and strength were significantly weaker in the JTJ than in both CMJ tests for all strength measures (p = 0.001-0.044) except one. Maximum strength and impulse at ∼60% 1RM did not seem to sufficiently capture the capabilities associated with JTJ height, highlighting the importance of employing tests targeting performance-relevant neuromuscular characteristics when assessing jump-related strength in handball players. Further, CMJ height seemed to represent a wider range of strength capabilities and care should be taken when using it as a proxy for handball-specific movements.

Implementation Evaluation of "Steering Teens Safe": Engaging Parents to Deliver a New Parent-Based Teen Driving Intervention to Their Teens

Science.gov (United States)

Ramirez, Marizen; Yang, Jingzhen; Young, Tracy; Roth, Lisa; Garinger, Anne; Snetselaar, Linda; Peek-Asa, Corinne

2013-01-01

Parents play a fundamental role in teaching their children safe driving skills to reduce risk of motor vehicle crashes, the leading cause of death for teens. "Steering Teens Safe" is a new parent-based intervention that equips parents with communication skills to talk about, demonstrate, and practice safe driving behaviors and skills…

Development of the HD-Teen Inventory.

Science.gov (United States)

Driessnack, Martha; Williams, Janet K; Barnette, J Jackson; Sparbel, Kathleen J; Paulsen, Jane S

2012-05-01

Adolescents, who have a parent with Huntington Disease (HD), not only are at genetic risk for HD but also are witness to its onset and devastating clinical progression as their parent declines. To date, no mechanism has been developed to direct health care providers to the atypical adolescent experiences of these teens. The purpose of this report is to describe the process of developing the HD-Teen Inventory clinical assessment tool. Forty-eight teens and young adults from 19 U.S. states participated in the evaluation of the HD-Teen Inventory tool. Following item analysis, the number of items was reduced and item frequency and reaction scales were combined, based on the strong correlation (r = .94). The resultant tool contains 15 inventory and 2 open-ended response items. The HD-Teen Inventory emerged as a more compact and efficient tool for identifying the most salient concerns of at-risk teens in HD families in research and/or clinical practice.

Freeze Frame 2012: A Snapshot of America's Teens

Science.gov (United States)

Stewart, Alison; Kaye, Kelleen

2012-01-01

When it comes to making decisions about sex, teens today are doing far better than they were 20 years ago. Fewer teens are having sex, and among those who are, more teens are using contraception. The happy result is that teen pregnancy and birth rates have declined dramatically. Despite this extraordinary progress, teen pregnancy and childbearing…

Homosexuality: Facts for Teens

Science.gov (United States)

... Talking to Your Kids About VirginityTalking to Your Kids About Sex Home Family Health Kids and Teens Homosexuality: Facts ... by: familydoctor.org editorial staff Categories: Family Health, Kids and Teens, Prevention and Wellness, Sex and Birth Control, Sex and SexualityTags: female, Gay ...

Coordination in vertical jumping

NARCIS (Netherlands)

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

1988-01-01

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

Estimation of Jump Tails

DEFF Research Database (Denmark)

Bollerslev, Tim; Todorov, Victor

We propose a new and flexible non-parametric framework for estimating the jump tails of Itô semimartingale processes. The approach is based on a relatively simple-to-implement set of estimating equations associated with the compensator for the jump measure, or its "intensity", that only utilizes...... the weak assumption of regular variation in the jump tails, along with in-fill asymptotic arguments for uniquely identifying the "large" jumps from the data. The estimation allows for very general dynamic dependencies in the jump tails, and does not restrict the continuous part of the process...... and the temporal variation in the stochastic volatility. On implementing the new estimation procedure with actual high-frequency data for the S&P 500 aggregate market portfolio, we find strong evidence for richer and more complex dynamic dependencies in the jump tails than hitherto entertained in the literature....

Special Considerations in Distracted Driving with Teens

Science.gov (United States)

Durbin, Dennis R; McGehee, Daniel V; Fisher, Donald; McCartt, Anne

2014-01-01

Novice teen drivers have long been known to have an increased risk of crashing, as well as increased tendencies toward unsafe and risky driving behaviors. Teens are unique as drivers for several reasons, many of which have implications specifically in the area of distracted driving. This paper reviews several of these features, including the widespread prevalence of mobile device use by teens, their lack of driving experience, the influence of peer passengers as a source of distraction, the role of parents in influencing teens’ attitudes and behaviors relevant to distracted driving and the impact of laws designed to prevent mobile device use by teen drivers. Recommendations for future research include understanding how engagement in a variety of secondary tasks by teen drivers affects their driving performance or crash risk; understanding the respective roles of parents, peers and technology in influencing teen driver behavior; and evaluating the impact of public policy on mitigating teen crash risk related to driver distraction. PMID:24776228

Ages and Stages: Teen

Science.gov (United States)

... Syndrome Tanning and Tanning Salon Safety Tips for Young People Teenagers and Gangs Teens and Acne Treatment Teens and Sun: Keeping Them Safe Without Ruining Their Fun The Teenage Brain VIDEO Ways To Build Your Teenager’s Self-Esteem What’s Going On in the Teenage Brain? Zits ...

Parental perceptions of teen driving: Restrictions, worry and influence.

Science.gov (United States)

Jewett, Amy; Shults, Ruth A; Bhat, Geeta

2016-12-01

Parents play a critical role in preventing crashes among teens. Research of parental perceptions and concerns regarding teen driving safety is limited. We examined results from the 2013 Summer ConsumerStyles survey that queried parents about restrictions placed on their teen drivers, their perceived level of "worry" about their teen driver's safety, and influence of parental restrictions regarding their teen's driving. We produced frequency distributions for the number of restrictions imposed, parental "worry," and influence of rules regarding their teen's driving, reported by teen's driving license status (learning to drive or obtained a driver's license). Response categories were dichotomized because of small cell sizes, and we ran separate log-linear regression models to explore whether imposing all four restrictions on teen drivers was associated with either worry intensity ("a lot" versus "somewhat, not very much or not at all") or perceived influence of parental rules ("a lot" versus "somewhat, not very much or not at all"). Among the 456 parent respondents, 80% reported having restrictions for their teen driver regarding use of safety belts, drinking and driving, cell phones, and text messaging while driving. However, among the 188 parents of licensed teens, only 9% reported having a written parent-teen driving agreement, either currently or in the past. Worrying "a lot" was reported less frequently by parents of newly licensed teens (36%) compared with parents of learning teens (61%). Parents report having rules and restrictions for their teen drivers, but only a small percentage formalize the rules and restrictions in a written parent-teen driving agreement. Parents worry less about their teen driver's safety during the newly licensed phase, when crash risk is high as compared to the learning phase. Further research is needed into how to effectively support parents in supervising and monitoring their teen driver. Published by Elsevier Ltd.

Real Teens, Real Tours: Teen Engagement Strategies for the One-Time Visit

Science.gov (United States)

Kusuma, Krista Dahl; Wyrick, Gabrielle

2014-01-01

The teen behavior typically exhibited in school visit groups is often read by museum teachers as resistance or disengagement, when the opposite is more likely the case. This paper attempts to dispel some of the myths around teen behavior and serve as a practical guide to museum educators who desire a deeper, more successful engagement with teen…

Reduced Disparities in Birth Rates Among Teens

Science.gov (United States)

... Teens Winnable Battles Social Media at CDC Reduced Disparities in Birth Rates among Teens Aged 15–19 ... Pregnancy Prevention Community-Wide Initiative. National Rates and Disparities Nationally, the teen birth rate (number of births ...

Children & Teens (with Lupus)

Science.gov (United States)

... nine. blog Lupus at school: A guide for parents and kids Advice for communicating with your child's school about their lupus and ... teens on adjusting to life with lupus For teens, living with lupus can require some major ... in school Advice from parents and education experts on 504 and Individualized Education ...

Teens and Research.

Science.gov (United States)

Neuhaus, Carolyn Plunkett

2016-10-01

On seeing promising results in a small number of patients, some researchers are conducting trials to determine whether deep brain stimulation (DBS) is an effective treatment for anorexia nervosa (AN). This article asks whether we should open enrollment in trials of DBS for AN to adolescents. Despite concerns about informed consent, parental consent, and unforeseeable psychological sequelae, the article concludes that the risks to anorexic adolescents associated with participation in trials of DBS are reasonable considering the substantial risks of not enrolling teens with AN in research on DBS. The seriousness of AN, its high incidence in teens, and serious shortfalls in the AN treatment literature point to the need for improved, evidence-based treatments for teens with AN. This unmet need generates an obligation on the part of researchers and physicians to promote and conduct research on AN in adolescents.

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

Science.gov (United States)

Virmavirta, Mikko; Kivekäs, Juha

2012-09-01

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

Deriving appropriate boundary conditions, and accelerating position-jump simulations, of diffusion using non-local jumping

International Nuclear Information System (INIS)

Taylor, P R; Baker, R E; Yates, C A

2015-01-01

In this paper we explore lattice-based position-jump models of diffusion, and the implications of introducing non-local jumping; particles can jump to a range of nearby boxes rather than only to their nearest neighbours. We begin by deriving conditions for equivalence with traditional local jumping models in the continuum limit. We then generalize a previously postulated implementation of the Robin boundary condition for a non-local process of arbitrary maximum jump length, and present a novel implementation of flux boundary conditions, again generalized for a non-local process of arbitrary maximum jump length. In both these cases we validate our results using stochastic simulation. We then proceed to consider two variations on the basic diffusion model: a hybrid local/non-local scheme suitable for models involving sharp concentration gradients, and the implementation of biased jumping. In all cases we show that non-local jumping can deliver substantial time savings for stochastic simulations. (paper)

Vital signs: teen pregnancy--United States, 1991--2009.

Science.gov (United States)

2011-04-08

In 2009, approximately 410,000 teens aged 15-19 years gave birth in the United States, and the teen birth rate remains higher than in other developed countries. To describe U.S. trends in teen births and related factors, CDC used data on 1) teen birth rates during 1991-2009 from the National Vital Statistics System, 2) sexual intercourse and contraceptive use among high school students during 1991-2009 from the national Youth Risk Behavior Survey, and 3) sex education, parent communication, use of long-acting reversible contraceptives (LARCs), and receipt of reproductive health services among teens aged 15-19 years from the 2006-2008 National Survey of Family Growth. In 2009, the national teen birth rate was 39.1 births per 1,000 females, a 37% decrease from 61.8 births per 1,000 females in 1991 and the lowest rate ever recorded. State-specific teen birth rates varied from 16.4 to 64.2 births per 1,000 females and were highest among southern states. Birth rates for black and Hispanic teens were 59.0 and 70.1 births per 1,000 females, respectively, compared with 25.6 for white teens. From 1991 to 2009, the percentage of high school students who ever had sexual intercourse decreased from 54% to 46%, and the percentage of students who had sexual intercourse in the past 3 months but did not use any method of contraception at last sexual intercourse decreased from 16% to 12%. From 1999 to 2009, the percentage of students who had sexual intercourse in the past 3 months and used dual methods at last sexual intercourse (condoms with either birth control pills or the injectable contraceptive Depo-Provera) increased from 5% to 9%. During 2006-2008, 65% of female teens and 53% of male teens received formal sex education that covered saying no to sex and provided information on methods of birth control. Overall, 44% of female teens and 27% of male teens had spoken with their parents about both topics, but among teens who had ever had sexual intercourse, 20% of females and 31

Understanding multiple levels of norms about teen pregnancy and their relationships to teens' sexual behaviors.

Science.gov (United States)

Mollborn, Stefanie; Domingue, Benjamin W; Boardman, Jason D

2014-06-01

Researchers seeking to understand teen sexual behaviors often turn to age norms, but they are difficult to measure quantitatively. Previous work has usually inferred norms from behavioral patterns or measured group-level norms at the individual level, ignoring multiple reference groups. Capitalizing on the multilevel design of the Add Health survey, we measure teen pregnancy norms perceived by teenagers, as well as average norms at the school and peer network levels. School norms predict boys' perceived norms, while peer network norms predict girls' perceived norms. Peer network and individually perceived norms against teen pregnancy independently and negatively predict teens' likelihood of sexual intercourse. Perceived norms against pregnancy predict increased likelihood of contraception among sexually experienced girls, but sexually experienced boys' contraceptive behavior is more complicated: When both the boy and his peers or school have stronger norms against teen pregnancy he is more likely to contracept, and in the absence of school or peer norms against pregnancy, boys who are embarrassed are less likely to contracept. We conclude that: (1) patterns of behavior cannot adequately operationalize teen pregnancy norms, (2) norms are not simply linked to behaviors through individual perceptions, and (3) norms at different levels can operate independently of each other, interactively, or in opposition. This evidence creates space for conceptualizations of agency, conflict, and change that can lead to progress in understanding age norms and sexual behaviors.

Vital Signs-Preventing Pregnancy in Younger Teens

Centers for Disease Control (CDC) Podcasts

2014-04-08

This podcast is based on the April 2014 CDC Vital Signs report. Births to teens are declining, still, in 2012, more than 86,000 teens ages 15 to 17 gave birth. This program discusses what health care providers, parents, and teens can do to help prevent teen pregnancy.  Created: 4/8/2014 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/8/2014.

Preventing Pregnancy in Younger Teens PSA (:60)

Centers for Disease Control (CDC) Podcasts

2014-04-08

This 60 second public service announcement is based on the April 2014 CDC Vital Signs report. Births to teens are declining, still, more than 305,000 teens ages 15 to 19 gave birth. This program discusses what health care providers, parents, and teens can do to help prevent teen pregnancy.  Created: 4/8/2014 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/8/2014.

Sex Differences in Countermovement Jump Phase Characteristics

Directory of Open Access Journals (Sweden)

John J. McMahon

2017-01-01

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

Influence of Knee-to-Feet Jump Training on Vertical Jump and Hang Clean Performance.

Science.gov (United States)

Stark, Laura; Pickett, Karla; Bird, Michael; King, Adam C

2016-11-01

Stark, L, Pickett, K, Bird, M, and King, AC. Influence of knee-to-feet jump training on vertical jump and hang clean performance. J Strength Cond Res 30(11): 3084-3089, 2016-From a motor learning perspective, the practice/training environment can result in positive, negative, or neutral transfer to the testing conditions. The purpose of this study was to examine the training effect of a novel movement (knee-to-feet [K2F] jumps) and whether a 6-week training program induced a positive transfer effect to other power-related movements (vertical jump and hang clean [HC]). Twenty-six intercollegiate athletes from power-emphasized sports were paired and counter-balanced into a control (i.e., maintained their respective sport-specific lifting regimen) or an experimental group (i.e., completed a 6-week progressive training program of K2F jumps in addition to respective lifting regimen). A pre- and posttest design was used to investigate the effect of training on K2F jump height and transfer effect to vertical jump height (VJH) and 2-repetition maximum (RM) HC performance. A significant increase in K2F jump height was found for the experimental group. Vertical jump height significantly increased from pre- to posttest but no group or interaction (group × time) effect was found, and there were nonsignificant differences for HC. Posttest data showed significant correlations between all pairs of the selected exercises with the highest correlation between K2F jump height and VJ H (R = 0.40) followed by VJH and 2RM HC (R = 0.38) and 2RM HC and K2F jump height (R = 0.23). The results suggest that K2F jump training induced the desired learning effect but was specific to the movement in that no effect of transfer occurred to the other power-related movements. This finding is value for strength and condition professionals who design training programs to enhance athletic performance.

School start times and teen driver crashes : traffic tech.

Science.gov (United States)

2015-12-01

Sleep health has become an increasingly important and studied : topic in the last decade. So much so that a number of : school districts across the United States have explored changing, : or have already changed their high-school start times to : a l...

Teens-as-teachers nutrition program increases interest in science among schoolchildren and fosters self-efficacy in teens

Directory of Open Access Journals (Sweden)

Virginia L.J. Bolshakova

2018-04-01

Full Text Available The Healthy Living Ambassador Program brings health, teen leadership, and teamwork to California's elementary school gardens through interdisciplinary UC Cooperative Extension collaboration, community-based partnerships and teen teaching. During spring 2015, teen ambassadors trained by Extension educators and volunteers at UC Elkus Ranch in San Mateo County taught nutrition science, food cultivation and healthy living skills in an 8-week, garden-based, after-school nutrition and physical education program for elementary school children in an urban setting. We conducted a pilot study using a mixed-methods approach to measure and explore the program's impact on children's vegetable selection and consumption preferences, as well as perceived self-efficacy in teen healthy living behavior. The children trended toward an increased preference for gardening, cooking and science, and teens displayed an increase in perceived health self-efficacy.

Later School Start Times: What Informs Parent Support or Opposition?

Science.gov (United States)

Dunietz, Galit Levi; Matos-Moreno, Amilcar; Singer, Dianne C; Davis, Matthew M; O'Brien, Louise M; Chervin, Ronald D

2017-07-15

To investigate parental knowledge about adolescent sleep needs, and other beliefs that may inform their support for or objection to later school start times. In 2014, we conducted a cross-sectional, Internet-based survey of a nationally representative sample of parents as part of the C.S. Mott Children's Hospital National Poll on Children's Health. Parents with teens aged 13-17 years reported their children's sleep patterns and school schedules, and whether the parents supported later school start times (8:30 am or later). Responses associated with parental support of later school start times were examined with logistic regression analysis. Overall, 88% of parents reported school start times before 8:30 am, and served as the analysis sample (n = 554). In this group, 51% expressed support for later school start times. Support was associated with current school start times before 7:30 am (odds ratio [OR] = 3.1 [95% confidence interval (CI) 1.2, 8.4]); parental opinion that their teen's current school start time was "too early" (OR = 3.8 [1.8, 7.8]); and agreement with American Academy of Pediatrics recommendations about school start times (OR = 4.7 [2.2, 10.1]). Support also was associated with anticipation of improved school performance (OR = 3.0 [1.5, 5.9]) or increased sleep duration (OR = 4.0 [1.8, 8.9]) with later school start times. Conversely, parents who anticipated too little time for after-school activities (OR = 0.5 [0.3, 0.9]) and need for different transportation plans (OR = 0.5 [0.2, 0.9]) were often less supportive. Parental education about healthy sleep needs and anticipated health benefits may increase their support for later school start times. Educational efforts should also publicize the positive experiences of communities that have made this transition, with regard to limited adverse effect on after-school activity schedules and transportation. © 2017 American Academy of Sleep Medicine

Effect of an Arm Swing on Countermovement Vertical Jump Performance in Elite Volleyball Players

Directory of Open Access Journals (Sweden)

Vaverka Frantisek

2016-12-01

Full Text Available The aim of this study was to determine how elite volleyball players employed the arm swing (AS to enhance their jump performance. The study assessed how the AS influenced the duration and magnitude of the vertical ground reaction force (VGRF during the main phases (preparatory, braking and accelerating of the countermovement vertical jump (CMVJ, the starting position of the body at the beginning of the accelerating phase and the moment when the AS began contributing to increasing the jump height. Eighteen elite volleyball players performed three CMVJs with and without an AS. Kinetics and kinematics data were collected using two Kistler force plates and the C-motion system. The time and force variables were evaluated based on the VGRF, and the position of the body and the trajectory of the arm movement were determined using kinematic analysis. The AS improved the CMVJ by increasing the jump height by 38% relative to jumping without an AS. The AS significantly shortened the braking phase and prolonged the accelerating phase, however, it did not influence the preparatory phase or the overall jump duration. The AS also significantly increased the average force during the accelerating phase as well as the accelerating impulse. The AS upward began at 76% into the overall jump duration. The AS did not influence the body position at the beginning of the accelerating phase. These findings can be used to improve performance of the CMVJ with the AS and in teaching beginning volleyball players proper jumping technique.

PTSD in Children and Teens

Science.gov (United States)

... for PTSD » Public » PTSD in Children and Teens PTSD: National Center for PTSD Menu Menu PTSD PTSD Home For the Public ... Enter ZIP code here Enter ZIP code here PTSD in Children and Teens Public This section is ...

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

Science.gov (United States)

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

2010-01-01

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

Mental Health and Teens: Watch for Danger Signs

Science.gov (United States)

... Gradeschool Teen Dating & Sex Fitness Nutrition Driving Safety School Substance Use Young Adult Healthy Children > Ages & Stages > Teen > Mental Health and Teens: Watch for Danger Signs Ages & Stages ...

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

Science.gov (United States)

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

2015-09-22

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

Hop, Step, Step and Jump : Towards Real-World Complexity @ Delft University of Technology

NARCIS (Netherlands)

Pruyt, E.; Slinger, J.H.; Van Daalen, C.; Yucel, G.; Thissen, W.A.H.

2009-01-01

This paper deals with System Dynamics education at Delft University of Technology, the Netherlands. It focuses more specifically on the quadruple jump approach towards dealing with real-world dynamic complexity. The paper starts with an overview of the System Dynamics courses, situated within the

Validity of Hip-worn Inertial Measurement Unit Compared to Jump Mat for Jump Height Measurement in Adolescents.

Science.gov (United States)

Rantalainen, T; Hesketh, K D; Rodda, C; Duckham, R L

2018-06-16

Jump tests assess lower body power production capacity, and can be used to evaluate athletic ability and development during growth. Wearable inertial measurement units (IMU) seem to offer a feasible alternative to laboratory-based equipment for jump height assessments. Concurrent validity of these devices for jump height assessments has only been established in adults. Therefore, the purpose of this study was to evaluate the concurrent validity of IMU-based jump height estimate compared to contact mat-based jump height estimate in adolescents. Ninety-five adolescents (10-13 years-of-age; girls N=41, height = 154 (SD 9) cm, weight = 44 (11) kg; boys N=54, height=156 (10) cm, weight = 46 (13) kg) completed three counter-movement jumps for maximal jump height on a contact mat. Inertial recordings (accelerations, rotations) were concurrently recorded with a hip-worn IMU (sampling at 256 Hz). Jump height was evaluated based on flight time. The mean IMU-derived jump height was 27.1 (SD 3.8) cm, and the corresponding mean jump-mat-derived value was 21.5 (3.4) cm. While a significant 26% mean difference was observed between the methods (5.5 [95% limits of agreement 2.2 to 8.9] cm, p = 0.006), the correspondence between methods was excellent (ICC = 0.89). The difference between methods was weakly positively associated with jump height (r = 0.28, P = 0.007). Take-off velocity derived jump height was also explored but produced only fair congruence. In conclusion, IMU-derived jump height exhibited excellent congruence to contact mat-based jump height and therefore presents a feasible alternative for jump height assessments in adolescents. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

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

Science.gov (United States)

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

2018-05-01

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

Do State-Based Policies Have an Impact on Teen Birth Rates and Teen Abortion Rates in the United States?

Science.gov (United States)

Chevrette, Marianne; Abenhaim, Haim Arie

2015-10-01

The United States has one of the highest teen birth rates among developed countries. Interstate birth rates and abortion rates vary widely, as do policies on abortion and sex education. The objective of our study is to assess whether US state-level policies regarding abortion and sexual education are associated with different teen birth and teen abortion rates. We carried out a state-level (N = 51 [50 states plus the District of Columbia]) retrospective observational cross-sectional study, using data imported from the National Vital Statistics System. State policies were obtained from the Guttmacher Institute. We used descriptive statistics and regression analysis to study the association of different state policies with teen birth and teen abortion rates. The state-level mean birth rates, when stratifying between policies protective and nonprotective of teen births, were not statistically different-for sex education policies, 39.8 of 1000 vs 45.1 of 1000 (P = .2187); for mandatory parents' consent to abortion 45 of 1000, vs 38 of 1000 when the minor could consent (P = .0721); and for deterrents to abortion, 45.4 of 1000 vs 37.4 of 1000 (P = .0448). Political affiliation (35.1 of 1000 vs 49.6 of 1000, P births. Lower teen abortion rates were, however, associated with restrictive abortion policies, specifically lower in states with financial barriers, deterrents to abortion, and requirement for parental consent. While teen birth rates do not appear to be influenced by state-level sex education policies, state-level policies that restrict abortion appear to be associated with lower state teen abortion rates. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Teens, Kindness and Cruelty on Social Network Sites: How American Teens Navigate the New World of "Digital Citizenship"

Science.gov (United States)

Lenhart, Amanda; Madden, Mary; Smith, Aaron; Purcell, Kristen; Zickuhr, Kathryn; Rainie, Lee

2011-01-01

Social media use has become so pervasive in the lives of American teens that having a presence on a social network site is almost synonymous with being online. Fully 95% of all teens ages 12-17 are now online and 80% of those online teens are users of social media sites. The authors focused their attention in this research on social network sites…

Do Bilateral Vertical Jumps With Reactive Jump Landings Achieve Osteogenic Thresholds With and Without Instruction in Premenopausal Women?

Science.gov (United States)

Clissold, Tracey L; Winwood, Paul W; Cronin, John B; De Souza, Mary Jane

2018-04-01

Jumps have been investigated as a stimulus for bone development; however, effects of instruction, jump type, and jump-landing techniques need investigation. This study sought to identify whether ground reaction forces (GRFs) for bilateral vertical jumps (countermovement jumps and drop jumps) with reactive jump-landings (ie, jumping immediately after initial jump-landing), with instruction and with instruction withdrawn, achieve magnitudes and rates of strain previously shown to improve bone mass among premenopausal women. Twenty-one women (Mean ± SD: 43.3 ± 5.9 y; 69.4 ± 9.6 kg; 167 ± 5.5 cm; 27.5 ± 8.7% body fat) performed a testing session 'with instruction' followed by a testing session performed 1 week later with 'instruction withdrawn.' The magnitudes (4.59 to 5.49 body weight [BW]) and rates of strain (263 to 359 BW·s -1 ) for the jump-landings, performed on an AMTI force plate, exceeded previously determined thresholds (>3 BWs and >43 BW·s -1 ). Interestingly, significantly larger peak resultant forces, (↑10%; P = .002) and peak rates of force development (↑20%; P jump-landing (postreactive jump). Small increases (ES = 0.22-0.42) in all landing forces were observed in the second jump-landing with 'instruction withdrawn.' These jumps represent a unique training stimulus for premenopausal women and achieve osteogenic thresholds thought prerequisite for bone growth.

Vital Signs-Preventing Teen Pregnancy

Centers for Disease Control (CDC) Podcasts

This podcast is based on the April 2015 CDC Vital Signs report. Teen births in the U.S. have declined, but still, more than 273,000 infants were born to teens ages 15 to 19 in 2013. Learn about the most effective types of birth control.

Factors associated with driving in teens with autism spectrum disorders.

Science.gov (United States)

Huang, Patty; Kao, Trudy; Curry, Allison E; Durbin, Dennis R

2012-01-01

To compare the characteristics of driving and nondriving teens and explore the driving outcomes for teens with higher functioning autism spectrum disorders. Parents of teens aged 15 to 18 years with a parent-reported diagnosis of an autism spectrum disorder enrolled in Interactive Autism Network, an online research registry, were eligible for this cross-sectional study. An online survey was used for data collection. A total of 297 parents completed the survey. Sixty-three percent of teens currently drive or plan to drive. Twenty-nine percent of the teens who are age-eligible to drive currently drive. Compared with age-eligible but nondriving teens, a greater proportion of driving teens were in full-time regular education (p public transportation. Driving predictors included individualized education plans with driving goals, indicators of functional status (classroom placement, college aspiration, and job experience), and parent experience with teaching teens to drive. Twelve percent of teens received driving citations, and 12% of teens had been involved in a motor vehicle crash. Although a significant proportion of teens with higher functioning autism spectrum disorders were driving or learning to drive, the fact that most driving teens' individualized education plans did not include driving goals suggests an area of opportunity for improvement in transition planning. Driving teens were more frequently in regular education settings with college aspirations, which could help schools identify potential drivers.

Why Are My Breasts Different Sizes? (For Teens)

Science.gov (United States)

... Feelings Expert Answers Q&A Movies & More for Teens Teens site Sitio para adolescentes Body Mind Sexual Health ... Why Are My Breasts Different Sizes? KidsHealth / For Teens / Why Are My Breasts Different Sizes? Print Having ...

Family communication patterns and teen drivers' attitudes toward driving safety.

Science.gov (United States)

Yang, Jingzhen; Campo, Shelly; Ramirez, Marizen; Krapfl, Julia Richards; Cheng, Gang; Peek-Asa, Corinne

2013-01-01

Family communication patterns (FCPs) play an important role in reducing the risk-taking behaviors of teens, such as substance use and safer sex. However, little is known about the relationship between family communication and teen driving safety. We analyzed the baseline data from a randomized trial that included 163 parent-teen dyads, with teens who would be receiving their intermediate driver's license within 3 months. FCPs were divided into four types-pluralistic, protective, consensual, and laissez-faire-and were correlated with the frequency of parent-teen discussions and teens' driving safety attitudes. The ratings on four types of FCPs were distributed quite evenly among teens and parents. Parents and teens agreed on their FCP ratings (p = .64). In families with communication patterns that were laissez-faire, protective, and pluralistic, parents talked to their teens less about safe driving than did parents in families with a consensual communication pattern (p < .01). Moreover, the frequency of parent-teen communication about safe driving was positively associated with teen attitudes toward safe driving (adjusted β = 0.35, p = .03). Health care providers need to encourage parents, particularly those with non-consensual FCPs, to increase frequency of parent-teen interactions. Copyright © 2013 National Association of Pediatric Nurse Practitioners. Published by Mosby, Inc. All rights reserved.

Parental perceptions of teen driving: Restrictions, worry and influence☆

Science.gov (United States)

Jewett, Amy; Shults, Ruth A.; Bhat, Geeta

2016-01-01

Introduction Parents play a critical role in preventing crashes among teens. Research of parental perceptions and concerns regarding teen driving safety is limited. We examined results from the 2013 Summer ConsumerStyles survey that queried parents about restrictions placed on their teen drivers, their perceived level of “worry” about their teen driver’s safety, and influence of parental restrictions regarding their teen’s driving. Methods We produced frequency distributions for the number of restrictions imposed, parental “worry,” and influence of rules regarding their teen’s driving, reported by teen’s driving license status (learning to drive or obtained a driver’s license). Response categories were dichotomized because of small cell sizes, and we ran separate log-linear regression models to explore whether imposing all four restrictions on teen drivers was associated with either worry intensity (“a lot” versus “somewhat, not very much or not at all”) or perceived influence of parental rules (“a lot” versus “somewhat, not very much or not at all”). Results Among the 456 parent respondents, 80% reported having restrictions for their teen driver regarding use of safety belts, drinking and driving, cell phones, and text messaging while driving. However, among the 188 parents of licensed teens, only 9% reported having a written parent-teen driving agreement, either currently or in the past. Worrying “a lot” was reported less frequently by parents of newly licensed teens (36%) compared with parents of learning teens (61%). Conclusions and Practical Applications Parents report having rules and restrictions for their teen drivers, but only a small percentage formalize the rules and restrictions in a written parent-teen driving agreement. Parents worry less about their teen driver’s safety during the newly licensed phase, when crash risk is high as compared to the learning phase. Further research is needed into how to effectively

How Much Sleep Do I Need? (For Teens)

Science.gov (United States)

... Videos for Educators Search English Español How Much Sleep Do I Need? KidsHealth / For Teens / How Much ... enough sleep. Why Don't Teens Get Enough Sleep? Until recently, teens often got a bad rap ...

Variation in free jumping technique within and among horses with little experience in show jumping

NARCIS (Netherlands)

Santamaria, S.; Bobbert, M.F.; Back, W.; Barneveld, A.; van Weeren, P.R.

2004-01-01

Objective - To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among

Validity of a Jump Mat for assessing Countermovement Jump Performance in Elite Rugby Players.

Science.gov (United States)

Dobbin, Nick; Hunwicks, Richard; Highton, Jamie; Twist, Craig

2017-02-01

This study determined the validity of the Just Jump System ® (JJS) for measuring flight time, jump height and peak power output (PPO) in elite rugby league players. 37 elite rugby league players performed 6 countermovement jumps (CMJ; 3 with and 3 without arms) on a jump mat and force platform. A sub-sample (n=28) was used to cross-validate the equations for flight time, jump height and PPO. The JJS systematically overestimated flight time and jump height compared to the force platform (Pjump height ( with R 2 =0.945; without R 2 =0.987). Our equations revealed no systematic difference between corrected and force platform scores and an improved the agreement for flight time (Ratio limits of agreement: with 1.00 vs. 1.36; without 1.00 vs. 1.16) and jump height ( with 1.01 vs. 1.34; without 1.01 vs. 1.15), meaning that our equations can be used to correct JJS scores for elite rugby players. While our equation improved the estimation of PPO ( with 1.02; without 1.01) compared to existing equations (Harman: 1.20; Sayers: 1.04), this only accounted for 64 and 69% of PPO. © Georg Thieme Verlag KG Stuttgart · New York.

Adult outcomes of teen mothers across birth cohorts

Directory of Open Access Journals (Sweden)

Anne Driscoll

2014-04-01

Full Text Available Background: Teen and young adult mothers have lower socioeconomic status than older mothers. Objective: This study analyzes the socioeconomic status (SES of teen, young adult, and older adult mothers across four five-year birth cohorts from 1956 to 1975 who were teens from 1971 to 1994. Methods: Data were pooled from the 1995, 2002, and 2006-2010 National Survey of Family Growth (NSFG. Mothers were categorized by age at first birth and by their birth cohorts. The SES (education, single motherhood, poverty, employment of teen, young adult, and older mothers was compared across cohorts and within cohorts. Results: Among teen mothers, the odds of fulltime employment improved across birth cohorts and the odds of educational attainment beyond high school did not vary. Their odds of single motherhood and living in poverty increased across cohorts. The odds of higher education and single motherhood increased across birth cohorts for young adult mothers as did the odds of living in poverty, even if working fulltime. Among older adult mothers, educational attainment and the odds of single motherhood rose for recent cohorts. Conclusions: Comparisons between teen mothers and both young adult and all adult mothers within cohorts suggest that gaps in single motherhood and poverty between teen and adult mothers have widened over time, to the detriment of teen mothers. Teen mothers have become more likely to be single and poor than in the past and compared to older mothers.

Adolescent bariatric surgery program characteristics: the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study experience.

Science.gov (United States)

Michalsky, Marc P; Inge, Thomas H; Teich, Steven; Eneli, Ihuoma; Miller, Rosemary; Brandt, Mary L; Helmrath, Michael; Harmon, Carroll M; Zeller, Meg H; Jenkins, Todd M; Courcoulas, Anita; Buncher, Ralph C

2014-02-01

The number of adolescents undergoing weight loss surgery (WLS) has increased in response to the increasing prevalence of severe childhood obesity. Adolescents undergoing WLS require unique support, which may differ from adult programs. The aim of this study was to describe institutional and programmatic characteristics of centers participating in Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS), a prospective study investigating safety and efficacy of adolescent WLS. Data were obtained from the Teen-LABS database, and site survey completed by Teen-LABS investigators. The survey queried (1) institutional characteristics, (2) multidisciplinary team composition, (3) clinical program characteristics, and (4) clinical research infrastructure. All centers had extensive multidisciplinary involvement in the assessment, pre-operative education, and post-operative management of adolescents undergoing WLS. Eligibility criteria and pre-operative clinical and diagnostic evaluations were similar between programs. All programs have well-developed clinical research infrastructure, use adolescent-specific educational resources, and maintain specialty equipment, including high weight capacity diagnostic imaging equipment. The composition of clinical team and institutional resources is consistent with current clinical practice guidelines. These characteristics, coupled with dedicated research staff, have facilitated enrollment of 242 participants into Teen-LABS. © 2013 Published by Elsevier Inc.

Vital signs: Repeat births among teens - United States, 2007-2010.

Science.gov (United States)

2013-04-05

Teen childbearing has potential negative health, economic, and social consequences for mother and child. Repeat teen childbearing further constrains the mother's education and employment possibilities. Rates of preterm and low birth weight are higher in teens with a repeat birth, compared with first births. To assess patterns of repeat childbearing and postpartum contraceptive use among teens, CDC analyzed natality data from the National Vital Statistics System (NVSS) and the Pregnancy Risk Assessment Monitoring System (PRAMS) from 2007-2010. Based on 2010 NVSS data from all 50 states and the District of Columbia, of more than 367,000 births to teens aged 15-19 years, 18.3% were repeat births. The percentage of teen births that represented repeat births decreased by 6.2% between 2007 and 2010. Disparities in repeat teen births exist by race/ethnicity, with the highest percentages found among American Indian/Alaska Natives (21.6%), Hispanics (20.9%), and non-Hispanic blacks (20.4%) and lowest among non-Hispanic whites (14.8%). Wide geographic disparities in the percentage of teen births that were repeat births also exist, ranging from 22% in Texas to 10% in New Hampshire. PRAMS data from 16 reporting areas (15 states and New York City) indicate that 91.2% of teen mothers used a contraceptive method 2-6 months after giving birth, but only 22.4% of teen mothers used the most effective methods. Teens with a previous live birth were significantly more likely to use the most effective methods postpartum compared with those with no prior live birth (29.6% versus 20.9%, respectively). Non-Hispanic white and Hispanic teens were significantly more likely to use the most effective methods than non-Hispanic black teens (24.6% and 27.9% versus 14.3%, respectively). The percentage of teens reporting postpartum use of the most effective methods varied greatly geographically across the PRAMS reporting areas, ranging from 50.3% in Colorado to 7.2% in New York State. Although the

SARS – virus jumps species

Indian Academy of Sciences (India)

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

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

Science.gov (United States)

Bedi, John F.; And Others

1987-01-01

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

Young Adult Outcomes of Children Born to Teen Mothers: Effects of Being Born during Their Teen or Later Years

Science.gov (United States)

Lipman, Ellen L.; Georgiades, Katholiki; Boyle, Michael H.

2011-01-01

Objective: Children of teen mothers exhibit adverse outcomes through adolescence. It is unclear whether these adverse outcomes extend to adulthood and apply to all of her children, or only those born when she was a teen. We examine the associations between young adult functioning and being born to a teen mother aged less than or equal to 20 years…

Preventing Teen Pregnancy PSA (:60)

Centers for Disease Control (CDC) Podcasts

This 60 second public service announcement is based on the April 2015 CDC Vital Signs report. Teen births in the U.S. have declined, but still, more than 273,000 infants were born to teens ages 15 to 19 in 2013. Learn about the most effective types of birth control.

What are quantum jumps?

International Nuclear Information System (INIS)

Cook, R.J.

1988-01-01

This paper answers the title question by giving an operational definition of quantum jumps based on measurement theory. This definition forms the basis of a theory of quantum jumps which leads to a number of testable predictions. Experiments are proposed to test the theory. The suggested experiments also test the quantum Zeno paradox, i.e., they test the proposition that frequent observation of a quantum system inhibits quantum jumps in that system. (orig.)

Parenting Skills: Tips for Raising Teens

Science.gov (United States)

... adult is no small task. Understand the parenting skills you need to help guide your teen. By ... teen and encourage responsible behavior. Use these parenting skills to deal with the challenges of raising a ...

PCOS: What Teens Need to Know

Science.gov (United States)

... Turner Syndrome Featured Resource Find an Endocrinologist Search PCOS for Teens September 2013 Download PDFs English Espanol ... PCOS Challenge womenshealth.gov Teens Health What is PCOS? PCOS, which stands for polycystic ovary syndrome, is ...

Leadership Skill Development of Teen Leaders.

Science.gov (United States)

Kleon, Scott; Rinehart, Susan

1998-01-01

Teen participants in the Ohio 4-H Teen Community Leadership College (n=64) perceived their leadership skills to be much higher after the program. They appeared to need improvement in initiative, assertiveness, and objectivity. (SK)

Trends in Alabama teen driving death and injury.

Science.gov (United States)

Monroe, Kathy; Irons, Elizabeth; Crew, Marie; Norris, Jesse; Nichols, Michele; King, William D

2014-09-01

Motor vehicle crashes (MVCs) are a leading cause of morbidity and mortality in teens. Alabama has been in the Top 5 states for MVC fatality rate among teens in the United States for several years. Twelve years of teen MVC deaths and injuries were evaluated. Our hypothesis is that the teen driving motor vehicle-related deaths and injuries have decreased related to legislative and community awareness activities. A retrospective analysis of Alabama teen MVC deaths and injury for the years 2000 to 2011 was conducted. MVC data were obtained from a Fatality Analysis Reporting System data set managed by the Center for Advanced Public Safety at the University of Alabama. A Lowess regression-scattergram analysis was used to identify period specific changes in deaths and injury over time. Statistical analysis was conducted using True Epistat 5.0 software. When the Lowess regression was applied, there was an obvious change in the trend line in 2007. To test that observation, we then compared medians in the pre-2007 and post-2007 periods, which validated our observation. Moreover, it provided a near-even number of observations for comparison. The Spearman rank correlation was used to test for correlation of deaths and injury over time. The Mann-Whitney U-test was used to evaluate median differences in deaths and injury comparing pre-2007 and post-2007 data. Alabama teen MVC deaths and injury demonstrated a significant negative correlation over the 12-year period (Rs for deaths and injury, -0.87 [p teen driver deaths and injury have decreased during the 12-year study period, most notably after 2006. Factors that may have contributed to this trend may include stricter laws for teen drivers (enacted in 2002 and updated in 2010), less teen driving because of a nationwide economic downturn, delayed licensing in teens, steady improvements in overall seat belt use, and heightened public awareness of risky behaviors in teen driving.

Teen Sleep: Why Is Your Teen So Tired?

Science.gov (United States)

... A consensus statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine. 2016;12:785. Teens, young adults and sleep. American Academy of Sleep Medicine. http://www.aasmnet.org/. Accessed June 29, 2017. ...

Preventing Repeat Teen Births PSA (:60)

Centers for Disease Control (CDC) Podcasts

This 60 second public service announcement is based on the April 2013 CDC Vital Signs report, which discusses repeat teen births and ways teens, parents and guardians, health care providers, and communities can help prevent them.

Get Your Teen Screened for Depression

Science.gov (United States)

... Topic En español Get Your Teen Screened for Depression Browse Sections The Basics Overview What Is Depression? ... 1 of 9 sections The Basics: What Is Depression? What is depression? Teen depression can be a ...

Kidney Stones in Children and Teens

Science.gov (United States)

... Issues Listen Español Text Size Email Print Share Kidney Stones in Children and Teens Page Content Article ... teen girls having the highest incidence. Types of Kidney Stones There are many different types of kidney ...

Falling teen pregnancy, birthrates: what's behind the declines?

Science.gov (United States)

Donovan, P

1998-10-01

About half of the almost 1 million US teenagers who become pregnant each year carry their pregnancies to term and give birth. However, after years of steady increases, teen birthrates in the US are lower and pregnancy rates have fallen to their lowest level in 20 years. Teenage sexual activity is also declining. Over the period 1991-96, the birthrate in the US among teens declined from the 20-year high of 62.1 births/1000 females aged 15-19 to 54.4/1000. This 12% decline comes after a 24% increase in the birthrate between 1986 and 1991. Declines in the teen birthrate were observed for the nation overall, as well as in each state, ranging from 6% in Alabama to 29% in Alaska. The teen birthrate among Blacks declined 21% to reach a record low of 91.4/1000 in 1996, while the rate for Hispanic teens barely changed during 1991-95, but eventually declined 5% during 1995-96 to 101.8/1000. The birthrate among non-Hispanic White teens declined 9% during the period to 48.1/1000, while the birthrate for teens aged 15-17 fell 13% during the period and 9% for 18-19 year olds. Pregnancy rates among women aged 15-19 years declined 14% between 1990 and 1995, to 101.1/1000, the lowest level since the mid-1970s. Although researchers are unsure why teen pregnancy and birthrates have fallen, recent survey data suggest that the declines have occurred because both fewer teens are having sex and more sexually active adolescents are using contraception.

Prenatal and postnatal cocaine exposure predict teen cocaine use

Science.gov (United States)

Delaney-Black, Virginia; Chiodo, Lisa M.; Hannigan, John H.; Greenwald, Mark K.; Janisse, James; Patterson, Grace; Huestis, Marilyn A.; Partridge, Robert T.; Ager, Joel; Sokol, Robert J.

2015-01-01

Preclinical studies have identified alterations in cocaine and alcohol self-administration and behavioral responses to pharmacological challenges in adolescent offspring following prenatal exposure. To date, no published human studies have evaluated the relation between prenatal cocaine exposure and postnatal adolescent cocaine use. Human studies of prenatal cocaine-exposed children have also noted an increase in behaviors previously associated with substance use/abuse in teens and young adults, specifically childhood and teen externalizing behaviors, impulsivity, and attention problems. Despite these findings, human research has not addressed prior prenatal exposure as a potential predictor of teen drug use behavior. The purpose of this study was to evaluate the relations between prenatal cocaine exposure and teen cocaine use in a prospective longitudinal cohort (n = 316) that permitted extensive control for child, parent and community risk factors. Logistic regression analyses and Structural Equation Modeling revealed that both prenatal exposure and postnatal parent/caregiver cocaine use were uniquely related to teen use of cocaine at age 14 years. Teen cocaine use was also directly predicted by teen community violence exposure and caregiver negativity, and was indirectly related to teen community drug exposure. These data provide further evidence of the importance of prenatal exposure, family and community factors in the intergenerational transmission of teen/young adult substance abuse/use. PMID:20609384

Jump probabilities in the non-Markovian quantum jump method

International Nuclear Information System (INIS)

Haerkoenen, Kari

2010-01-01

The dynamics of a non-Markovian open quantum system described by a general time-local master equation is studied. The propagation of the density operator is constructed in terms of two processes: (i) deterministic evolution and (ii) evolution of a probability density functional in the projective Hilbert space. The analysis provides a derivation for the jump probabilities used in the recently developed non-Markovian quantum jump (NMQJ) method (Piilo et al 2008 Phys. Rev. Lett. 100 180402).

Pediatrician attitudes, knowledge, and practice behavior regarding teen driving safety.

Science.gov (United States)

Campbell, Brendan T; Borrup, Kevin; Corsi, John M; Kelliher, Kristine M; Saleheen, Hassan; Banco, Leonard; Lapidus, Garry

2009-01-01

Each year about 4,000 teens ages 16-19 die on U.S. roads. Injury prevention counseling is recommended as a valuable and cost-effective part of routine health supervision. This study describes pediatrician knowledge and practice regarding teen driving safety. A 31-item self-administered survey was mailed to pediatricians. 160 of 392 pediatricians (41%) completed the survey. During a health supervision visit 93% of pediatricians reported discussing seat belt use, 89% impaired driving, 54% teen licensing laws, and 16% parent teen contract. Half reported having a teen in their practice killed in a crash. A majority surveyed report discussing and counseling teens on first wave teen driver safety issues (seat belts, alcohol use), but most do not discuss graduated driver licensing laws or related issues. Broadly adopted, this inexpensive counseling approach, could lead to reductions in teen motorvehicle crash injuries.

Realized Jump Risk and Equity Return in China

Directory of Open Access Journals (Sweden)

Guojin Chen

2014-01-01

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

Reducing the Teen Death Rate. KIDS COUNT Indicator Brief

Science.gov (United States)

Shore, Rima; Shore, Barbara

2009-01-01

Life continues to hold considerable risk for adolescents in the United States. In 2006, the teen death rate stood at 64 deaths per 100,000 teens (13,739 teens) (KIDS COUNT Data Center, 2009). Although it has declined by 4 percent since 2000, the rate of teen death in this country remains substantially higher than in many peer nations, based…

Theory of boiling-up jump

International Nuclear Information System (INIS)

Labuntsov, D.A.; Avdeev, A.A.

1981-01-01

Concept of boiling-up jump representing a zone of intense volume boiling-up separating overtaking flow of overheated metastable liquid from an area of equilibrium flow located below along the flow is introduced. It is shown that boiling-up jump is a shock wave of rarefaction. It is concluded that entropy increment occurs on the jump. Characteristics of adiabatic shock wave curve of boiling- up in ''pressure-specific volume'' coordinates have been found and its form has been investigated. Stability of boiling-up jump has been analyzed as well. On the basis of approach developed analysis is carried out on the shock adiobatic curve of condensation. Concept of boiling-up jump may be applied to the analysis of boiling-up processes when flowing liquid through packings during emergency pressure drop etc [ru

Parents, Teens, and Online Privacy

Science.gov (United States)

Madden, Mary; Cortesi, Sandra; Gasser, Urs; Lenhart, Amanda; Duggan, Maeve

2012-01-01

Most parents of teenagers are concerned about what their teenage children do online and how their behavior could be monitored by others. Some parents are taking steps to observe, discuss, and check up on their children's digital footprints. A new survey of 802 parents and their teens shows that: (1) 81% of parents of online teens say they are…

Prenatal and postnatal cocaine exposure predict teen cocaine use.

Science.gov (United States)

Delaney-Black, Virginia; Chiodo, Lisa M; Hannigan, John H; Greenwald, Mark K; Janisse, James; Patterson, Grace; Huestis, Marilyn A; Partridge, Robert T; Ager, Joel; Sokol, Robert J

2011-01-01

Preclinical studies have identified alterations in cocaine and alcohol self-administration and behavioral responses to pharmacological challenges in adolescent offspring following prenatal exposure. To date, no published human studies have evaluated the relation between prenatal cocaine exposure and postnatal adolescent cocaine use. Human studies of prenatal cocaine-exposed children have also noted an increase in behaviors previously associated with substance use/abuse in teens and young adults, specifically childhood and teen externalizing behaviors, impulsivity, and attention problems. Despite these findings, human research has not addressed prior prenatal exposure as a potential predictor of teen drug use behavior. The purpose of this study was to evaluate the relations between prenatal cocaine exposure and teen cocaine use in a prospective longitudinal cohort (n=316) that permitted extensive control for child, parent and community risk factors. Logistic regression analyses and Structural Equation Modeling revealed that both prenatal exposure and postnatal parent/caregiver cocaine use were uniquely related to teen use of cocaine at age 14 years. Teen cocaine use was also directly predicted by teen community violence exposure and caregiver negativity, and was indirectly related to teen community drug exposure. These data provide further evidence of the importance of prenatal exposure, family and community factors in the intergenerational transmission of teen/young adult substance abuse/use. Copyright © 2010 Elsevier Inc. All rights reserved.

[Effects of TeenSTAR, an abstinence only sexual education program, on adolescent sexual behavior].

Science.gov (United States)

Vigil, Pilar; Riquelme, Rosa; Rivadeneira, Rosario; Aranda, Waldo

2005-10-01

Urgent measures are required to stop the increase in the frequency of pregnancies and sexually transmitted diseases among teenagers. A means of facing this problem is promoting sexual abstinence among youngsters. There are studies that confirm the efficacy of this approach. To show the results of the application of a holistic sexuality program (TeenSTAR) among Chilean teenagers. Students attending basic or high school were divided into a control or study group. The control group (342 students) received the usual education on sexuality given by their schools and the study group (398 students) participated in twelve TeenSTAR sessions lasting 1.5 hours each, given by a trained professor. Assessment of achievements was made using an anonymous questionnaire answered at the start and end of the program. The rates of sexual initiation among control and study groups were 15 and 6.5%, respectively. Among sexually active students, 20% of those in the study group and 9% of those in the control group discontinued sexual activity. A higher proportion of students in the TeenSTAR program retarded their sexual initiation or discontinued sexual activity and found more reasons to maintain sexual abstinence than control students.

Teens Take Stand on Bullying, but Resources Are Needed

Science.gov (United States)

Education Digest: Essential Readings Condensed for Quick Review, 2011

2011-01-01

Nine percent of 13- to 15-year-old teens and 3% of teens 16 to 18 years old say they are "always" or "often" bullied to a point that makes them feel very sad, angry, sad, or upset. Over one-quarter of all teens say they are "sometimes" bullied to this point. This article presents some results of a "Harris Poll" of 776 teens surveyed online in…

Evaluation of an infant simulator intervention for teen pregnancy prevention.

Science.gov (United States)

Herrman, Judith W; Waterhouse, Julie K; Chiquoine, Julie

2011-01-01

To evaluate the effectiveness of simulation as a strategy to influence teens' perceptions of pregnancy and parenting. This pilot study was a preexperimental, one group pre/posttest design. The school-based wellness center of a high school was the setting for the weekly sessions and the pre/posttest administration. Sample members participated in 6 weekly Baby Think it Over (BTIO) classes and an infant simulator experience. The final sample included 79 teens age 14 to 18 years who attended one of eight BTIO sessions. We used the Thoughts on Teen Parenting Survey (TTPS) to assess the perceptions of teens with regard to the costs and rewards associated with teen parenting. The TTPS yields a composite score of the teen attitudes toward the teen parenting experience and eight subscale scores that assess different areas of teen life. No significant differences were found in the mean pre/posttest scores or in correlations of the demographic data and mean scores. Two significant differences in pre/posttest subscale scores were in the areas of friends and personal characteristics. The results of this study suggest that the effectiveness of using infant simulators to influence the perceptions of teens about the reality of teen parenting is minimal. © 2011 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

BPS Jumping Loci are Automorphic

Science.gov (United States)

Kachru, Shamit; Tripathy, Arnav

2018-06-01

We show that BPS jumping loci-loci in the moduli space of string compactifications where the number of BPS states jumps in an upper semi-continuous manner—naturally appear as Fourier coefficients of (vector space-valued) automorphic forms. For the case of T 2 compactification, the jumping loci are governed by a modular form studied by Hirzebruch and Zagier, while the jumping loci in K3 compactification appear in a story developed by Oda and Kudla-Millson in arithmetic geometry. We also comment on some curious related automorphy in the physics of black hole attractors and flux vacua.

Teens, Health and Technology: A National Survey

Directory of Open Access Journals (Sweden)

Ellen Wartella

2016-06-01

Full Text Available In the age of digital technology, as teens seem to be constantly connected online, via social media, and through mobile applications, it is no surprise that they increasingly turn to digital media to answer their health questions. This study is the first of its kind to survey a large, nationally-representative sample of teens to investigate how they use the newest digital technologies, including mobile apps, social networking sites, electronic gaming and wearable devices, to explore health topics. The survey covered the types of health topics teens most frequently search for, which technologies they are most likely to use and how they use them, and whether they report having changed their behaviors due to digital health information. In addition, this survey explores how the digital divide continues to impact adolescents. Results of this study indicate that teens are concerned about many health issues, ranging from fitness, sexual activity, drugs, hygiene as well as mental health and stress. As teens virtually always have a digital device at their fingertips, it is clear that public health interventions and informational campaigns must be tailored to reflect the ways that teens currently navigate digital health information and the health challenges that concern them most.

Grieving Teen

Science.gov (United States)

... time when they have been taught that showing emotion is something that girls do – but macho guys ... not caring about anything and a lack of motivation or interest. Help the teen understand that these ...

Getting Started with Processing

CERN Document Server

Reas, Casey

2010-01-01

Learn computer programming the easy way with Processing, a simple language that lets you use code to create drawings, animation, and interactive graphics. Programming courses usually start with theory, but this book lets you jump right into creative and fun projects. It's ideal for anyone who wants to learn basic programming, and serves as a simple introduction to graphics for people with some programming skills. Written by the founders of Processing, this book takes you through the learning process one step at a time to help you grasp core programming concepts. You'll learn how to sketch wi

Optimal Ski Jump

Science.gov (United States)

Rebilas, Krzysztof

2013-01-01

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

Teen Dating Violence Prevention: Cluster-Randomized Trial of Teen Choices, an Online, Stage-Based Program for Healthy, Nonviolent Relationships.

Science.gov (United States)

Levesque, Deborah A; Johnson, Janet L; Welch, Carol A; Prochaska, Janice M; Paiva, Andrea L

2016-07-01

Teen dating violence is a serious public health problem. A cluster-randomized trial was conducted to assess the efficacy of Teen Choices , a 3-session online program that delivers assessments and individualized guidance matched to dating history, dating violence experiences, and stage of readiness for using healthy relationship skills. For high risk victims of dating violence, the program addresses readiness to keep oneself safe in relationships. Twenty high schools were randomly assigned to the Teen Choices condition ( n =2,000) or a Comparison condition ( n =1,901). Emotional and physical dating violence victimization and perpetration were assessed at 6 and 12 months in the subset of participants (total n =2,605) who reported a past-year history of dating violence at baseline, and/or who dated during the study. The Teen Choices program was associated with significantly reduced odds of all four types of dating violence (adjusted ORs ranging from .45 to .63 at 12 months follow-up). For three of the four violence outcomes, participants with a past-year history of that type of violence benefited significantly more from the intervention than students without a past-year history. The Teen Choices program provides an effective and practicable strategy for intervention for teen dating violence prevention.

The Teen Depression Awareness Project: Building an Evidence Base for Improving Teen Depression Care. Research Highlights

Science.gov (United States)

Adamson, David M.

2010-01-01

Depression's effects on adolescent functioning and family burden are not well understood; there is also limited understanding of teens' and parents' attitudes and knowledge about depression, how these and other factors influence readiness for treatment, and the barriers to care that teens and their parents encounter. To address these knowledge…

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

Science.gov (United States)

Virmavirta, M; Komi, P V

2001-12-01

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

Teen birth rates in sexually abused and neglected females.

Science.gov (United States)

Noll, Jennie G; Shenk, Chad E

2013-04-01

Prospectively track teen childbirths in maltreated and nonmaltreated females and test the hypothesis that child maltreatment is an independent predictor of subsequent teen childbirth over and above demographic characteristics and other risk factors. Nulliparous adolescent females (N = 435) aged 14 to 17 years were assessed annually through age 19 years. Maltreated females were referred by Child Protective Services agencies for having experienced substantiated sexual abuse, physical abuse, or neglect within the preceding 12 months. Comparison females were matched on race, family income, age and family constellation. Teen childbirth was assessed via self-report during annual interviews. Births were confirmed using hospital delivery records. Seventy participants gave birth during the study, 54 in the maltreated group and 16 in the comparison group. Maltreated females were twice as likely to experience teen childbirth after controlling for demographic confounds and known risk factors (odds ratio = 2.17, P = 0.01). Birth rates were highest for sexually abused and neglected females. Sexual abuse and neglect were both independent predictors of teen childbirth after controlling for demographic confounds, other risk factors and alternative forms of maltreatment occurring earlier in development. Results provide evidence that sexual abuse and neglect are unique predictors of subsequent teen childbirth. Partnerships between protective service providers and teen childbirth prevention strategists hold the best promise for further reducing the US teen birth rate. Additional research illuminating the pathways to teen childbirth for differing forms of maltreatment is needed so that tailored interventions can be realized.

Changing Sociodemographic Factors and Teen Fertility: 1991–2009

Science.gov (United States)

Abma, Joyce C.

2018-01-01

This study analyzed the roles of trends in sociodemographic factors known to be related to the risk of a teen birth. The goal was to analyze the roles of these trends in maternal education, family structure and mother’s age at first birth in the likelihood of adolescents becoming teen mothers across multiple birth cohorts of women covering the years since 1991. Data are from the 1995, 2002, 2006–2010 and 2011–2013 National Surveys of Family Growth (NSFG). Consecutive birth cohorts of female respondents were constructed and retrospectively followed to estimate the risk of a teen birth for each cohort. Logistic regression models estimate the odds of a teen birth across cohorts and within strata of the predictors across cohorts. Maternal education rose across cohorts; the proportion who were non-Hispanic white declined. In general, the likelihood of an adolescent birth did not change within categories of the predictors that are considered at higher risk for a teen birth across birth cohorts. Specifically, there was no change in the odds of a teen birth among women whose mothers did not finish high school, those born to teen mothers and those not from two-parent families. The odds of a birth declined across cohorts for black women. The findings suggest that much of the decline in teen birth rates is due to declines in the proportion of teens in higher risk categories, rather than to declines within those categories. PMID:25680702

Individual flight styles in ski jumping: results obtained during Olympic Games competitions.

Science.gov (United States)

Schmölzer, B; Müller, W

2005-05-01

From the physics point of view, the jump length in ski jumping depends on: the in-run velocity v(0), the velocity perpendicular to the ramp v(p0) due to the athlete's jumping force, the lift and drag forces acting during take-off and during the flight, and the weight of the athlete and his equipment. The aerodynamic forces are a function of the flight position and of the equipment features. They are a predominant performance factor and can largely be influenced by the athlete. The field study conducted during the Olympic Games competitions 2002 at Park City (elevation: 2000 m) showed an impressive ability of the Olympic medallists to reproduce their flight style and remarkable differences between different athletes have been found. The aerodynamic forces are proportional to the air density. Elite athletes are able to adapt their flight style to thin air conditions in order to maximise jump length and to keep the flight stable. The effects of flight position variations on the performance have been analysed by means of a computer model which is based on the equations of motion and on wind tunnel data corresponding to the flight positions found in the field. Athletes have to solve extremely difficult optimisation problems within fractions of a second. The computer simulation can be used as a reliable starting point for the improvement of training methods and gives an insight into the "implicit" knowledge of physics that the ski jumping athlete must have available for a good performance.

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

Directory of Open Access Journals (Sweden)

Mandic Radivoj

2016-09-01

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

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

Science.gov (United States)

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

2016-09-01

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

Genetic Variability of Show Jumping Attributes in Young Horses Commencing Competing

Directory of Open Access Journals (Sweden)

Tomasz Próchniak

2015-08-01

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

Jump conditions in transonic equilibria

International Nuclear Information System (INIS)

Guazzotto, L.; Betti, R.; Jardin, S. C.

2013-01-01

In the present paper, the numerical calculation of transonic equilibria, first introduced with the FLOW code in Guazzotto et al.[Phys. Plasmas 11, 604 (2004)], is critically reviewed. In particular, the necessity and effect of imposing explicit jump conditions at the transonic discontinuity are investigated. It is found that “standard” (low-β, large aspect ratio) transonic equilibria satisfy the correct jump condition with very good approximation even if the jump condition is not explicitly imposed. On the other hand, it is also found that high-β, low aspect ratio equilibria require the correct jump condition to be explicitly imposed. Various numerical approaches are described to modify FLOW to include the jump condition. It is proved that the new methods converge to the correct solution even in extreme cases of very large β, while they agree with the results obtained with the old implementation of FLOW in lower-β equilibria.

Relationships between school start time, sleep duration, and adolescent behaviors.

Science.gov (United States)

Wahlstrom, Kyla L; Berger, Aaron T; Widome, Rachel

2017-06-01

The objectives were 2-fold: (1) to examine how high school start times relate to adolescent sleep duration, and (2) to test associations between sleep duration and mental health- and substance use-related issues and behaviors in teens. This study examines selected questions from survey data collected between 2010 and 2013 high school students. Respondents included more than 9000 students in grades 9 to 12 in 8 high schools in 5 school districts across the United States. The survey instrument is the 97-item Teen Sleep Habits Survey. Logistic regression models were used to calculate adjusted odds ratios and 95% confidence intervals. Because of clustering within schools and the use of repeated measures, generalized estimating equations were used to account for variance inflation. Greater sleep duration was associated with fewer reports of various mental health- and substance use-related issues and behaviors (all P values sleep reported, there was a 28% reduction in the adjusted odds of a participant reporting that he or she felt "unhappy, sad, or depressed." Later wake-up times were associated with a reduction in risk for some, but not all factors. Later start times were significantly associated with greater sleep duration. Given that later start times allow for greater sleep duration and that adequate sleep duration is associated with more favorable mental health- and substance use-related issues and behaviors, it is important that school districts prioritize exploring and implementing policies, such as delayed start times, that may increase the amount of sleep of adolescent students, which is needed for their optimal development. Copyright © 2017 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.

Measurement of L3 subshell absorption jump ratios and jump factors for high Z elements using EDXRF technique

International Nuclear Information System (INIS)

Kaçal, M.R.

2014-01-01

Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring L 3 -subshell absorption jump ratios, r L 3 and jump factors, J L 3 for high Z elements. Jump factors and jump ratios for these elements have been determined by measuring L 3 subshell fluorescence parameters such as L 3 subshell X-ray production cross section σ L 3 , L 3 subshell fluorescence yield, ω L 3 , total L 3 subshell and higher subshells photoionization cross section σ L T . Measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation experimental geometry. Measured values for jump factors and jump ratios have been compared with theoretically calculated and other experimental values. - Highlights: • This paper regards L 3 subshell absorption jump ratios and jump factors using the EDXRF method. • These parameters were measured using a new method. • This method is more useful than other methods which require much effort. • Results are in good agreement with theoretical and experimental values

Reframing the risks and losses of teen mothering.

Science.gov (United States)

SmithBattle, Lee

2009-01-01

Teen mothers often face a stigmatizing gaze based on the belief that early childbearing jeopardizes their life chances and the health and development of their children. Growing evidence suggests that the poor maternal-child outcomes associated with early childbearing have been overstated and may be explained by teen mothers' childhood disadvantage and adversities. After reviewing what is currently known about the relationships between early childbearing and maternal-child outcomes, as well as teen mothers' perspectives on mothering, clinical practices are suggested that address teen mothers' concerns, strengths, aspirations, and the long-term inequities that contribute to poor outcomes.

Health Concerns for Gay and Lesbian Teens

Science.gov (United States)

... Text Size Email Print Share Health Concerns for Gay and Lesbian Teens Page Content Article Body Sexual activity Most teens, whether they are gay, lesbian, bisexual , or straight, are not sexually active. ...

Optimal distance of an external focus of attention in standing long jump performance of athletes

Directory of Open Access Journals (Sweden)

Gh. Lotfi

2018-06-01

Full Text Available Background and Study Aim: Recently, studies have shown that an external focus of attention improves the performance of individuals. Some studies have also confirmed the superiority of distances away from body for external focus of attention. The aim of this study was to determine the optimal distance of an external focus of attention when performing athletes' standing long jump. Material and Method: 51 volunteer students (M age= 23.31 ± 5.26 years were selected as sample. At first all they performed a standing long jump in control status (without instruction for focus of attention. Then in an interpersonal counterbalanced design, a pair of jumps was performed with four different distances of an external focus of attention. These distances included 0.5, 2.5, 4 and 8 meters from the jump start line marked with colored tapes on the ground. Results: The results showed that having an external focus of attention compare to the control conditions has a significant advantage in the performance of the athlete's standing long jump. Also, the performance of athletes at different distances of an external focus of attention was compared. Results showed that the four-meter distance was significantly better performance than the half-meter distance of an external focus of attention. Conclusion: Four-meter distance can be introduced as the optimal distance of an external focus of attention in the performance of athletes’ standing long jump.

Are cellular phone blocking applications effective for novice teen drivers?

Science.gov (United States)

Creaser, Janet I; Edwards, Christopher J; Morris, Nichole L; Donath, Max

2015-09-01

Distracted driving is a significant concern for novice teen drivers. Although cellular phone bans are applied in many jurisdictions to restrict cellular phone use, teen drivers often report making calls and texts while driving. The Minnesota Teen Driver Study incorporated cellular phone blocking functions via a software application for 182 novice teen drivers in two treatment conditions. The first condition included 92 teens who ran a driver support application on a smartphone that also blocked phone usage. The second condition included 90 teens who ran the same application with phone blocking but which also reported back to parents about monitored risky behaviors (e.g., speeding). A third control group consisting of 92 novice teen drivers had the application and phone-based software installed on the phones to record cellular phone (but not block it) use while driving. The two treatment groups made significantly fewer calls and texts per mile driven compared to the control group. The control group data also demonstrated a higher propensity to text while driving rather than making calls. Software that blocks cellular phone use (except 911) while driving can be effective at mitigating calling and texting for novice teen drivers. However, subjective data indicates that some teens were motivated to find ways around the software, as well as to use another teen's phone while driving when they were unable to use theirs. Cellular phone bans for calling and texting are the first step to changing behaviors associated with texting and driving, particularly among novice teen drivers. Blocking software has the additional potential to reduce impulsive calling and texting while driving among novice teen drivers who might logically know the risks, but for whom it is difficult to ignore calling or texting while driving. Copyright © 2015 Elsevier Ltd and National Safety Council. All rights reserved.

Teens Will Be Teens: The Latest Brain Research Has a Lot to Say about Adolescent Behavior

Science.gov (United States)

Jones, Jami

2005-01-01

Most adults are challenged when it comes to understanding teens' motives. "What were they thinking of?" is an all-too-common response. Without a doubt, no developmental period in life is more confounding and baffling than adolescence. Until recently, erratic teen behavior was blamed on raging hormones, but scientific research in the last decade…

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

African Journals Online (AJOL)

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

Mother-daughter dyadic approach for starting preconception counseling at puberty in girls with diabetes.

Science.gov (United States)

Charron-Prochownik, Denise; Fischl, Andrea Rodgers; Choi, Jessica; Schmitt, Patricia L; White, Neil H; Becker, Dorothy; Downs, Julie; Hannan, Margaret; Thurheimer, Jennifer; Sereika, Susan M

2014-12-29

Preconception counseling (PC) significantly and inexpensively reduces risks of reproductive-health complications for women with diabetes. Our validated technology-based preconception counseling intervention, READY-Girls , is tailored for female teens with type 1 (T1D) and type 2 (T2D) diabetes and targets decision-making regarding effective family planning and seeking PC. Our teen-focused research was instrumental in changing the American Diabetes Association's Practice Recommendations to specify that preconception counseling should "Start at puberty…". This directive requires support from well-informed mothers of teens. Our goal is to provide both teen girls and their mothers with preconception counseling knowledge, and provide mothers with sex-communication training. Evaluation should focus on mother-daughter dyads. This feasibility study explored mother's and daughter's awareness and knowledge of diabetes and pregnancy, and preconception counseling; and compared mother-daughter responses using dyadic analyses. A mixed-method design was conducted with 10 mothers of daughters with T1D. Mothers were given READY-Girls intervention and completed knowledge and support questionnaires. Their responses were compared to those of their daughter's who were participating in a large randomized, control intervention trial with READY-Girls . The major theme from one-on-one interviews was, "I know nothing about diabetes/pregnancy risks and PC". Mother's and daughter's perceptions of having limited knowledge were confirmed by low knowledge scores. Mothers perceived giving higher levels of support compared to their daughter's perceptions of receiving support. Mothers can play a vital role in initiating discussions regarding reproductive-health with their daughters and reinforcing preconception counseling. Mother-daughter team approach for starting preconception counseling at puberty in girls with diabetes is feasible. Mother-daughter dyadic analyses can be important to explore

Mechanics of jumping on water

Science.gov (United States)

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

2017-10-01

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

A latent transition model of the effects of a teen dating violence prevention initiative.

Science.gov (United States)

Williams, Jason; Miller, Shari; Cutbush, Stacey; Gibbs, Deborah; Clinton-Sherrod, Monique; Jones, Sarah

2015-02-01

Patterns of physical and psychological teen dating violence (TDV) perpetration, victimization, and related behaviors were examined with data from the evaluation of the Start Strong: Building Healthy Teen Relationships initiative, a dating violence primary prevention program targeting middle school students. Latent class and latent transition models were used to estimate distinct patterns of TDV and related behaviors of bullying and sexual harassment in seventh grade students at baseline and to estimate transition probabilities from one pattern of behavior to another at the 1-year follow-up. Intervention effects were estimated by conditioning transitions on exposure to Start Strong. Latent class analyses suggested four classes best captured patterns of these interrelated behaviors. Classes were characterized by elevated perpetration and victimization on most behaviors (the multiproblem class), bullying perpetration/victimization and sexual harassment victimization (the bully-harassment victimization class), bullying perpetration/victimization and psychological TDV victimization (bully-psychological victimization), and experience of bully victimization (bully victimization). Latent transition models indicated greater stability of class membership in the comparison group. Intervention students were less likely to transition to the most problematic pattern and more likely to transition to the least problem class. Although Start Strong has not been found to significantly change TDV, alternative evaluation models may find important differences. Latent transition analysis models suggest positive intervention impact, especially for the transitions at the most and the least positive end of the spectrum. Copyright © 2015. Published by Elsevier Inc.

High Cholesterol in Children and Teens

Science.gov (United States)

... dairy products. The body needs some cholesterol to work properly. But if your child or teen has high cholesterol (too much cholesterol in the blood), he or she has a higher risk of coronary artery disease and other heart diseases. What causes high cholesterol in children and teens? Three main ...

Teen PACK: Population Awareness Campaign Kit.

Science.gov (United States)

Zero Population Growth, Inc., Washington, DC.

This packet of instructional materials is designed to teach teenagers about the effects of overpopulation on the world and on the individual. Information is presented in three related booklets. The first of the three parts of the "Teen Population Awareness Campaign Kit," illustrates overpopulation through profiles of teens living in…

A longitudinal examination of US teen childbearing and smoking risk

Science.gov (United States)

Mollborn, Stefanie; Woo, Juhee; Rogers, Richard G.

2018-01-01

BACKGROUND Teenage motherhood and smoking have important health implications for youth in the United States and globally, but the link between teen childbearing and subsequent smoking is inadequately understood. The selection of disadvantaged young women into early childbearing and smoking may explain higher smoking levels among teen mothers, but teen motherhood may also shape subsequent smoking through compromised maternal depression or socioeconomic status, and race/ethnicity may condition these processes. OBJECTIVE This study examines the relationship between US teen childbearing and subsequent daily smoking, accounting for prior smoking and selection processes related to social disadvantage. Analyses investigate whether socioeconomic status and depression in young adulthood explained any relationship between teen childbearing and daily smoking, as well as examining racial/ethnic heterogeneity in these processes. METHODS Multivariate binary logistic regression analyses employ the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 7,529). RESULTS The highest daily smoking prevalence occurred among non-Hispanic White teen mothers, with lower prevalence among Hispanic and non-Hispanic Black teen mothers. Compared to other women, teenage mothers are 2.5 times as likely to smoke daily in young adulthood. Their greater likelihood of daily smoking is due in part to selection and is also mediated by socioeconomic status in ways that differ by race/ethnicity. CONCLUSIONS The findings suggest that preventing teen pregnancy or ameliorating its socioeconomic consequences may decrease daily smoking in this vulnerable population. Reducing teen smoking, especially during pregnancy, could improve teen, maternal, and infant health and thereby increase US health and longevity. CONTRIBUTION This study provides new, nationally representative information about selection, mediation, and heterogeneity processes in the relationship between teen childbearing and

A longitudinal examination of US teen childbearing and smoking risk.

Science.gov (United States)

Mollborn, Stefanie; Woo, Juhee; Rogers, Richard G

2018-01-01

Teenage motherhood and smoking have important health implications for youth in the United States and globally, but the link between teen childbearing and subsequent smoking is inadequately understood. The selection of disadvantaged young women into early childbearing and smoking may explain higher smoking levels among teen mothers, but teen motherhood may also shape subsequent smoking through compromised maternal depression or socioeconomic status, and race/ethnicity may condition these processes. This study examines the relationship between US teen childbearing and subsequent daily smoking, accounting for prior smoking and selection processes related to social disadvantage. Analyses investigate whether socioeconomic status and depression in young adulthood explained any relationship between teen childbearing and daily smoking, as well as examining racial/ethnic heterogeneity in these processes. Multivariate binary logistic regression analyses employ the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 7,529). The highest daily smoking prevalence occurred among non-Hispanic White teen mothers, with lower prevalence among Hispanic and non-Hispanic Black teen mothers. Compared to other women, teenage mothers are 2.5 times as likely to smoke daily in young adulthood. Their greater likelihood of daily smoking is due in part to selection and is also mediated by socioeconomic status in ways that differ by race/ethnicity. The findings suggest that preventing teen pregnancy or ameliorating its socioeconomic consequences may decrease daily smoking in this vulnerable population. Reducing teen smoking, especially during pregnancy, could improve teen, maternal, and infant health and thereby increase US health and longevity. This study provides new, nationally representative information about selection, mediation, and heterogeneity processes in the relationship between teen childbearing and subsequent smoking.

Estimated Trans-Lamina Cribrosa Pressure Differences in Low-Teen and High-Teen Intraocular Pressure Normal Tension Glaucoma: The Korean National Health and Nutrition Examination Survey.

Directory of Open Access Journals (Sweden)

Si Hyung Lee

Full Text Available To investigate the association between estimated trans-lamina cribrosa pressure difference (TLCPD and prevalence of normal tension glaucoma (NTG with low-teen and high-teen intraocular pressure (IOP using a population-based study design.A total of 12,743 adults (≥ 40 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES from 2009 to 2012 were included. Using a previously developed formula, cerebrospinal fluid pressure (CSFP in mmHg was estimated as 0.55 × body mass index (kg/m2 + 0.16 × diastolic blood pressure (mmHg-0.18 × age (years-1.91. TLCPD was calculated as IOP-CSFP. The NTG subjects were divided into two groups according to IOP level: low-teen NTG (IOP ≤ 15 mmHg and high-teen NTG (15 mmHg < IOP ≤ 21 mmHg groups. The association between TLCPD and the prevalence of NTG was assessed in the low- and high-teen IOP groups.In the normal population (n = 12,069, the weighted mean estimated CSFP was 11.69 ± 0.04 mmHg and the weighted mean TLCPD 2.31 ± 0.06 mmHg. Significantly higher TLCPD (p < 0.001; 6.48 ± 0.27 mmHg was found in the high-teen NTG compared with the normal group. On the other hand, there was no significant difference in TLCPD between normal and low-teen NTG subjects (p = 0.395; 2.31 ± 0.06 vs. 2.11 ± 0.24 mmHg. Multivariate logistic regression analysis revealed that TLCPD was significantly associated with the prevalence of NTG in the high-teen IOP group (p = 0.006; OR: 1.09; 95% CI: 1.02, 1.15, but not the low-teen IOP group (p = 0.636. Instead, the presence of hypertension was significantly associated with the prevalence of NTG in the low-teen IOP group (p < 0.001; OR: 1.65; 95% CI: 1.26, 2.16.TLCPD was significantly associated with the prevalence of NTG in high-teen IOP subjects, but not low-teen IOP subjects, in whom hypertension may be more closely associated. This study suggests that the underlying mechanisms may differ between low-teen and high-teen NTG patients.

Vital Signs-Preventing Teen Pregnancy

Centers for Disease Control (CDC) Podcasts

2015-04-07

This podcast is based on the April 2015 CDC Vital Signs report. Teen births in the U.S. have declined, but still, more than 273,000 infants were born to teens ages 15 to 19 in 2013. Learn about the most effective types of birth control.  Created: 4/7/2015 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/7/2015.

The Educational Consequences of Teen Childbearing

Science.gov (United States)

Kane, Jennifer B.; Morgan, S. Philip; Harris, Kathleen Mullan; Guilkey, David K.

2013-01-01

A huge literature shows that teen mothers face a variety of detriments across the life course, including truncated educational attainment. To what extent is this association causal? The estimated effects of teen motherhood on schooling vary widely, ranging from no discernible difference to 2.6 fewer years among teen mothers. The magnitude of educational consequences is therefore uncertain, despite voluminous policy and prevention efforts that rest on the assumption of a negative and presumably causal effect. This study adjudicates between two potential sources of inconsistency in the literature—methodological differences or cohort differences—by using a single, high-quality data source: namely, The National Longitudinal Study of Adolescent Health. We replicate analyses across four different statistical strategies: ordinary least squares regression; propensity score matching; and parametric and semiparametric maximum likelihood estimation. Results demonstrate educational consequences of teen childbearing, with estimated effects between 0.7 and 1.9 fewer years of schooling among teen mothers. We select our preferred estimate (0.7), derived from semiparametric maximum likelihood estimation, on the basis of weighing the strengths and limitations of each approach. Based on the range of estimated effects observed in our study, we speculate that variable statistical methods are the likely source of inconsistency in the past. We conclude by discussing implications for future research and policy, and recommend that future studies employ a similar multimethod approach to evaluate findings. PMID:24078155

CDC Vital Signs: Preventing Repeat Teen Births

Science.gov (United States)

... control after they have given birth. Although teen birth rates have been falling for the last two decades, ... effective forms of birth control. SOURCE: National Vital Statistics System, teens, ages 15–19, 2010 Larger image ...

Force generation and temperature-jump and length-jump tension transients in muscle fibers.

Science.gov (United States)

Davis, J S; Rodgers, M E

1995-01-01

Muscle tension rises with increasing temperature. The kinetics that govern the tension rise of maximally Ca(2+)-activated, skinned rabbit psoas fibers over a temperature range of 0-30 degrees C was characterized in laser temperature-jump experiments. The kinetic response is simple and can be readily interpreted in terms of a basic three-step mechanism of contraction, which includes a temperature-sensitive rapid preequilibrium(a) linked to a temperature-insensitive rate-limiting step and followed by a temperature-sensitive tension-generating step. These data and mechanism are compared and contrasted with the more complex length-jump Huxley-Simmons phases in which all states that generate tension or bear tension are perturbed. The rate of the Huxley-Simmons phase 4 is temperature sensitive at low temperatures but plateaus at high temperatures, indicating a change in rate-limiting step from a temperature-sensitive (phase 4a) to a temperature-insensitive reaction (phase 4b); the latter appears to correlate with the slow, temperature-insensitive temperature-jump relaxation. Phase 3 is absent in the temperature-jump, which excludes it from tension generation. We confirm that de novo tension generation occurs as an order-disorder transition during phase 2slow and the equivalent, temperature-sensitive temperature-jump relaxation. PMID:7612845

Parenting teens with attention-deficit/hyperactivity disorder: challenges and opportunities.

Science.gov (United States)

Modesto-Lowe, Vania; Chaplin, Margaret; Godsay, Viraj; Soovajian, Victoria

2014-09-01

Attention-deficit/hyperactivity disorder (ADHD) presents in childhood with inattention, hyperactivity, and impulsivity and is associated with functional impairments. These children tend to display a variety of disruptive behaviors, which may worsen in adolescence. Teens with ADHD may show high levels of defiance, posing significant challenges for parents. Early efforts to understand parenting in the context of teen ADHD reveal high levels of parental stress and reactivity in response to the teen's ADHD symptoms. Subsequent research recognized that some of these parents have ADHD or other psychopathology that may contribute to maladaptive parenting. However, some parents adjust and demonstrate optimism and resilience in the face of their teens' ADHD. Recent research has identified parental factors (eg, emotional intelligence) and interventions (eg, mindfulness training) that may improve parenting/teen relationships and the developmental outcomes of teens. This article explores parenting teens with ADHD with a focus on these novel interventions. © The Author(s) 2014.

Especially for Teens: You and Your Sexuality

Science.gov (United States)

... QUESTIONS FAQ042 ESPECIALLY FOR TEENS You and Your Sexuality (Especially for Teens) • What happens during puberty? • What ... feelings expressed? There are many ways to express sexuality. Sexual intercourse is one way. Others include masturbation , ...

Evaluation of Teen Cuisine: An Extension-Based Cooking Program to Increase Self-efficacy in Teens

OpenAIRE

Petty, Heather Keyronica

2016-01-01

Heather K. Petty ABSTRACT Title: Evaluation of Teen Cuisine: An Extension-Based Cooking Program to Increase Self-efficacy in Teens Background: Childhood, adolescent, and adult obesity is a major health and economic concern affecting the United States and various countries across the globe. Obese children and adolescents are at a potential risk for developing certain chronic diseases as they transition into adulthood. There are community-based cooking intervention programs designed t...

Geographic and racial variation in teen pregnancy rates in Wisconsin.

Science.gov (United States)

Layde, Molly M; Remington, Patrick L

2013-08-01

Despite recent declines in teen birth rates, teenage pregnancy remains an important public health problem in Wisconsin with significant social, economic, and health-related effects. Compare and contrast teen birth rate trends by race, ethnicity, and county in Wisconsin. Teen (ages 15-19 years) birth rates (per 1000 teenage females) in Wisconsin from 2001-2010 were compared by racelethnicity and county of residence using data from the Wisconsin Interactive Statistics on Health. Teen birth rates in Wisconsin have declined by 20% over the past decade, from 35.5/1000 teens in 2001 to 28.3/1000 teens in 2010-a relative decline of 20.3%. However, trends vary by race, with declines among blacks (-33%) and whites (-26%) and increases among American Indians (+21%) and Hispanics (+30%). Minority teen birth rates continue to be 3 to 5 times greater than birth rates among whites. Rates varied even more by county, with an over 14-fold difference between Ozaukee County (7.8/1000) and Menominee County (114.2). Despite recent declines, teen pregnancy continues to be an important public health problem in Wisconsin. Pregnancy prevention programs should be targeted toward the populations and counties with the highest rates.

Biomechanics research in ski jumping, 1991-2006.

Science.gov (United States)

Schwameder, Hermann

2008-01-01

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

Performance analysis of jump-gliding locomotion for miniature robotics.

Science.gov (United States)

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

2015-03-26

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

Filtering and control of stochastic jump hybrid systems

CERN Document Server

Yao, Xiuming; Zheng, Wei Xing

2016-01-01

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

Evaluating opportunities for text message communication: a survey of parents and teens.

Science.gov (United States)

Ahlers-Schmidt, Carolyn R; Jones, Jordan T; Chesser, Amy; Weeks, Kerri

2013-09-01

Text messaging is a widespread, cost-effective method for communicating. It is widely used by both parents and teens. The study objective was to survey teens and their parents to assess the capability and willingness of teens to receive healthcare-related text messages from their physician. Parents and teens (12-17 years old) at an adolescent clinic were asked to complete surveys. Surveys were available in hard copy or electronically (via Survey Monkey) using computer kiosks in the waiting room. Approval was received from two local Institutional Review Boards. Of the 93 pairs who began the survey, 47 pairs (51%) qualified and completed both the teen and parent surveys. Over 85% of teens were willing to receive texts from their doctor. Teens were most interested in appointment reminders (81%), immunization reminders (53%), and general test results (for example, strep [53%]). Parents' willingness to allow teens to receive text messages directly varied by content. Many parents preferred to also receive a copy of any text message sent to their teen. Both parents and teens endorse using text messages for appointment reminders. Parents appear willing for their teens to receive some health information directly. Future research should evaluate the efficacy of using text messages for communication with teens to improve care and utilization of services for adolescents.

Development of a survey to assess adolescent perceptions of teen parenting.

Science.gov (United States)

Herrman, Judith W; Nandakumar, Ratna

2012-01-01

Initiatives designed to prevent teen pregnancy are often based on adult perceptions of the negative aspects of a teen birth. Qualitative research has revealed that teens may perceive positive rewards associated with teen parenting. These perceptions have not yet been examined through survey research. The theory of reasoned action proposes that individuals assess the costs and rewards prior to engaging in a behavior and provides a framework for the development of a survey instrument designed to measure adolescent thoughts about the costs and rewards of the teen parenting experience. This manuscript describes the development and testing of a quantitative survey instrument designed to measure adolescents' perceptions. Pretesting, piloting, exploratory factor analysis, and a variety of reliability and validity measures were used to determine the value of the measure. The thoughts on teen parenting survey (TTPS) demonstrates an alpha level of .90. The TTPS yields a cumulative score of teen perceptions about the impact of a teen birth during the adolescent years that may be used to assess youth beliefs, correlated with demographic data, used to identify teens at risk for pregnancy/parenting, or provide a pretest/posttest to assess the effectiveness of interventions designed to foster realistic attitudes toward teen parenting.

A longitudinal examination of US teen childbearing and smoking risk

Directory of Open Access Journals (Sweden)

Stefanie Mollborn

2018-02-01

Full Text Available Background: Teenage motherhood and smoking have important health implications for youth in the United States and globally, but the link between teen childbearing and subsequent smoking is inadequately understood. The selection of disadvantaged young women into early childbearing and smoking may explain higher smoking levels among teen mothers, but teen motherhood may also shape subsequent smoking through compromised maternal depression or socioeconomic status, and race/ethnicity may condition these processes. Objective: This study examines the relationship between US teen childbearing and subsequent daily smoking, accounting for prior smoking and selection processes related to social disadvantage. Analyses investigate whether socioeconomic status and depression in young adulthood explained any relationship between teen childbearing and daily smoking, as well as examining racial/ethnic heterogeneity in these processes. Methods: Multivariate binary logistic regression analyses employ the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 7,529. Results: The highest daily smoking prevalence occurred among non-Hispanic White teen mothers, with lower prevalence among Hispanic and non-Hispanic Black teen mothers. Compared to other women, teenage mothers are 2.5 times as likely to smoke daily in young adulthood. Their greater likelihood of daily smoking is due in part to selection and is also mediated by socioeconomic status in ways that differ by race/ethnicity. Conclusions: The findings suggest that preventing teen pregnancy or ameliorating its socioeconomic consequences may decrease daily smoking in this vulnerable population. Reducing teen smoking, especially during pregnancy, could improve teen, maternal, and infant health and thereby increase US health and longevity. Contribution: This study provides new, nationally representative information about selection, mediation, and heterogeneity processes in the relationship

Preventing Teen Pregnancy PSA (:60)

Centers for Disease Control (CDC) Podcasts

2015-04-07

This 60 second public service announcement is based on the April 2015 CDC Vital Signs report. Teen births in the U.S. have declined, but still, more than 273,000 infants were born to teens ages 15 to 19 in 2013. Learn about the most effective types of birth control.  Created: 4/7/2015 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/7/2015.

Mother-teen communication about weight management.

Science.gov (United States)

Dailey, René M; Thompson, Charee M; Romo, Lynsey Kluever

2014-01-01

Although research shows family members can influence each other's diet and exercise behaviors, the specific strategies that most effectively motivate individuals to enact healthy behaviors have not been revealed. Toward this goal, this study employed confirmation theory to assess how the quality of weight management (WM) communication between 107 mother-teen dyads was related to their diet and exercise behaviors as well as their subjective perceptions of the productivity of WM conversations. Confirmation theory proposes two components of confirmation: acceptance and challenge. Analyses revealed that accepting and challenging communication were both positively related to the perceived productivity of WM conversations. However, more complex associations emerged for diet and exercise. Acceptance was more helpful in motivating better eating habits for mothers with low health motivation and teens with high health motivation. For exercise, challenge was helpful in motivating teens with higher sensitivity about communicating about weight issues; however, counter to predictions, challenge was negatively related to exercise for teens with low health motivation and low sensitivity. These interactions, however, explained less variance than analyses for perceived effectiveness and satisfaction.

Teen driver crashes : a report to Congress

Science.gov (United States)

2008-07-01

This report summarizes what is known about the teen driver crash problem and reviews the research on the major contributing factors to the high teen crash rate. Dispositional factors, such as immaturity, inexperience, faulty judgment, and a higher pr...

A Study of Taiwanese Teens' Traditional and Cyberbullying Behaviors

Science.gov (United States)

Yang, Shu Ching; Lin, Chia-Ying; Chen, An-Sing

2014-01-01

This study examined several types of teen behaviors, specifically bullying, being bullied, and witnessing bullying, and analyzed teens' judgments of the seriousness of the bullying. A Bullying Behaviors Scale (BBS) was designed to investigate both traditional bullying (TB) and cyberbullying (CB) behaviors among teens in grades 5 through 11. The…

Jump spillover between oil prices and exchange rates

Science.gov (United States)

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

2017-11-01

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

Preventing Repeat Teen Births PSA (:60)

Centers for Disease Control (CDC) Podcasts

2013-04-02

This 60 second public service announcement is based on the April 2013 CDC Vital Signs report, which discusses repeat teen births and ways teens, parents and guardians, health care providers, and communities can help prevent them.  Created: 4/2/2013 by Centers for Disease Control and Prevention (CDC).   Date Released: 4/2/2013.

Teen Depression and Suicide: Effective Prevention and Intervention Strategies

Science.gov (United States)

King, Keith A.; Vidourek, Rebecca A.

2012-01-01

Teen depression and suicidal behaviors are intricately intertwined, with untreated depression being a leading cause of adolescent suicide. Most depressed or suicidal teens tend to show warning signs and possess specific risk factors. A key component to preventing teen depression is for adults to remain aware of such warning signs and risk factors…

Effects of a Teen Pregnancy Prevention Program on Teens' Attitudes toward Sexuality: A Latent Trait Modeling Approach

Science.gov (United States)

Thomas, Charles L.; Dimitrov, Dimiter M.

2007-01-01

The purpose of this study was to examine the effects of program interventions in a school-based teen pregnancy program on hypothesized constructs underlying teens' attitudes toward sexuality. An important task related to this purpose was the validation of the constructs and their stability from pre- to postintervention measures. Data from 1,136…

Emotionally troubled teens' help-seeking behaviors: an evaluation of surviving the Teens® suicide prevention and depression awareness program.

Science.gov (United States)

Strunk, Catherine M; Sorter, Michael T; Ossege, Julianne; King, Keith A

2014-10-01

Many school-based suicide prevention programs do not show a positive impact on help-seeking behaviors among emotionally troubled teens despite their being at high risk for suicide. This study is a secondary analysis of the Surviving the Teens(®) program evaluation to determine its effect on help-seeking behaviors among troubled youth. Results showed significant increases in mean scores of the Behavioral Intent to Communicate with Important Others Regarding Emotional Health Issues subscale (p Teens program has a positive effect on help-seeking behaviors in troubled youth. © The Author(s) 2013.

Characteristics of Air Entrainment in Hydraulic Jump

Science.gov (United States)

Albarkani, M. S. S.; Tan, L. W.; Al-Gheethi, A.

2018-04-01

The characteristics of hydraulic jump, especially the air entrainment within jump is still not properly understood. Therefore, the current work aimed to determine the size and number of air entrainment formed in hydraulic jump at three different Froude numbers and to obtain the relationship between Froude number with the size and number of air entrainment in hydraulic jump. Experiments of hydraulic jump were conducted in a 10 m long and 0.3 m wide Armfield S6MKII glass-sided tilting flume. Hydraulic jumps were produced by flow under sluice gate with varying Froude number. The air entrainment of the hydraulic jump was captured with a Canon Power Shot SX40 HS digital camera in video format at 24 frames per second. Three discharges have been considered, i.e. 0.010 m3/s, 0.011 m3/s, and 0.013 m3/s. For hydraulic jump formed in each discharge, 32 frames were selected for the purpose of analysing the size and number of air entrainment in hydraulic jump. The results revealed that that there is a tendency to have greater range in sizes of air bubbles as Fr1 increases. Experiments with Fr1 = 7.547. 7.707, and 7.924 shown that the number of air bubbles increases exponentially with Fr1 at a relationship of N = 1.3814 e 0.9795Fr1.

The validity and reliability of the my jump 2 app for measuring the reactive strength index and drop jump performance.

Science.gov (United States)

Haynes, Tom; Bishop, Chris; Antrobus, Mark; Brazier, Jon

2018-03-27

This is the first study to independently assess the concurrent validity and reliability of the My Jump 2 app for measuring drop jump performance. It is also the first to evaluate the app's ability to measure the reactive strength index (RSI). Fourteen male sport science students (age: 29.5 ± 9.9 years) performed three drop jumps from 20 cm and 40 cm (totalling 84 jumps), assessed via a force platform and the My Jump 2 app. Reported metrics included reactive strength index, jump height, ground contact time, and mean power. Measurements from both devices were compared using the intraclass correlation coefficient (ICC), Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation (CV) and BlandAltman plots. Near perfect agreement was seen between devices at 20 cm for RSI (ICC = 0.95) and contact time (ICC = 0.99) and at 40 cm for RSI (ICC = 0.98), jump height (ICC = 0.96) and contact time (ICC = 0.92); with very strong agreement seen at 20 cm for jump height (ICC = 0.80). In comparison with the force plate the app showed good validity for RSI (20 cm: r = 0.94; 40 cm; r = 0.97), jump height (20 cm: r = 0.80; 40 cm; r = 0.96) and contact time (20 cm = 0.96; 40 cm; r = 0.98). The results of the present study show that the My Jump 2 app is a valid and reliable tool for assessing drop jump performance.

Opportunity, community, and teen pregnancy in an Appalachian state.

Science.gov (United States)

Bickel, R; Weaver, S; Williams, T; Lange, L

1997-01-01

This study examines female adolescents' responses to opportunities, costs, and community in West Virginia. It is posited that adolescent women's responses to structurally determined contextual factors will be the most important determinant of the teen birth rate. It is posited that girls avoid becoming pregnant and work to stay in school as a wise investment in their future. The variation in males' participation in contributing to teen pregnancy is not considered due to data limitations. West Virginia is a state with low teen abortion rates and limited teen mobility out of state. Community is construed as having a positive sense of affiliation and value for adolescents. Community is measured by school size and a range of 7 measures of community social organization: percentage of urban population in the district, percentage Black, percentage neither Black nor White, level of educational attainment, percentage of college preparatory students, percentage of college students, and percentage of service employees. The 7 factors were reduced with principal component analysis to a measure of modernity. Findings indicate that the birth rate increased by 8% for every increase of 100 students in average school size. The modern variable, which indicates departures from traditional patterns of community organization, was positively, statistically significantly related to the teenage birth rate. The college degree variable was related to increased teen pregnancy as a departure from traditional norms and decreased teen pregnancy as a measure of opportunity. Findings contrast with traditional interpretations of teen pregnancy. Findings indicate that teen pregnancy reflects a lack of opportunity, a decline in traditional community patterns, and the replacement of traditional social relations by shifting labor market relations. Teen births are consequences of disadvantage and disruption as context-driven factors.

CDC Vital Signs: Teen Drinking and Driving

Science.gov (United States)

... short. Obey speed limits. Never use a cell phone or text while driving. Parents can Understand that most teens who drink ... number of teen passengers Never use a cell phone or text while driving Obey speed limits Get your copy of CDC's ...

Predicting vertical jump height from bar velocity.

Science.gov (United States)

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

2015-06-01

The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s(-2)). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r(2) = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r(2) = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key pointsVertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.The relationship between the point at which bar acceleration is less than -9.81 m·s(-2) and the real take-off is affected by the velocity of movement.Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.

Challenges to Breastfeeding Initiation and Duration for Teen Mothers.

Science.gov (United States)

Cota-Robles, Sonia; Pedersen, Laura; LeCroy, Craig Winston

The purpose of this study was to evaluate breastfeeding practices of teen mothers in a pre- and postnatal education and support program. We studied breastfeeding practices of primarily Hispanic and non-Hispanic White teen mothers who participated in the Teen Outreach Pregnancy Services (TOPS) program, which promoted breastfeeding through prenatal programming and postpartum support. Analyses identified the most common reasons participants had not breastfed and, for those who initiated breastfeeding, the most common reasons they stopped. Participants (g = 314) reported on whether and for how long they breastfed. Nearly all participants reported initiating breastfeeding but few breastfed to 6 months. For the most part, reasons they reported stopping breastfeeding paralleled those previously reported for adult mothers across the first several months of motherhood. We found that teen mothers can initiate breastfeeding at high rates. Results highlight areas in which teen mothers' knowledge and skills can be supported to promote breastfeeding duration, including pain management and better recognizing infant cues. Our findings expand limited previous research investigating reasons that teen mothers who initiate breastfeeding stop before 6 months.

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

International Nuclear Information System (INIS)

Kim, Seyoung

2017-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-04-15

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

Baby Think It Over: Using Role-Play To Prevent Teen Pregnancy.

Science.gov (United States)

Out, Jennifer W.; Lafreniere, Kathryn D.

2001-01-01

Examined the effectiveness of Baby Think It Over (BTIO), an infant simulation program that seeks to modify attitudes toward teen pregnancy and teen parenting. After experiencing BTIO, teens in the intervention group were more likely to accurately access their personal risk for an unplanned pregnancy than were teens in the comparison group. (Author)

Dynamic jump intensities and risk premiums

DEFF Research Database (Denmark)

Christoffersen, Peter; Ornthanalai, Chayawat; Jacobs, Kris

2012-01-01

We build a new class of discrete-time models that are relatively easy to estimate using returns and/or options. The distribution of returns is driven by two factors: dynamic volatility and dynamic jump intensity. Each factor has its own risk premium. The models significantly outperform standard...... models without jumps when estimated on S&P500 returns. We find very strong support for time-varying jump intensities. Compared to the risk premium on dynamic volatility, the risk premium on the dynamic jump intensity has a much larger impact on option prices. We confirm these findings using joint...

Racial Disparity, Depression, and Birth Outcomes Among Pregnant Teens.

Science.gov (United States)

Abdelaal, Hala; Mohamed, Mohamed A; Aly, Hany

2018-03-20

Objectives To examine the risk of premature delivery (PD) and small for gestational age (SGA) among pregnant teens with depressive disorders (DD), and the impact of race/ethnicity on these birth outcomes. Design/Methods We examined the hospital discharge records of pregnant mothers between the age of 13-18 year old who gave birth in the years 1994, 2000, 2006, and 2012 in the National Inpatient Sample database. We calculated the risk for PD and SGA among pregnant teens with and without DD in the overall population and within each race/ethnicity. Results Weighted sample included 1,023,586 pregnant teenage women. Prevalence of DD among teens was 0.93%, with a significantly increasing trend from 0.29% in 1994 to 2.01% in 2012 (p teens from 1994 to 2012. Prevalence of depression among teenage mothers was highest among Caucasians compared to other races. Prevalence of SGA among pregnant teens was 2.23% that significantly increased from 1.63% in 1994 to 3.44% in 2012 (p teens with DD had decreased risk for PD compared to AA without DD (OR 0.70; CI 0.57 - 0.387, p teens with DD had increased risk for SGA compared to Hispanics without DD (adjusted OR 1.53; CI 1.10-2.13, p teens. Less young teenage girls are giving birth in recent years. The impact of DD on PD and SGA differs according to race. More studies are warranted to examine underlining factors responsible for these findings.

Paediatrician knowledge, attitudes, and counselling patterns on teen driving.

Science.gov (United States)

Weiss, Jeffrey C; O'Neil, Joseph; Shope, Jean T; O'Connor, Karen G; Levin, Rebecca A

2012-02-01

Motor vehicle crashes (MVCs) are the leading cause of death among teenagers. Little is known about the content of US paediatrician counselling about teen driving. To examine US paediatrician knowledge, attitudes, and counselling patterns regarding teen driving. A random sample questionnaire was mailed to American Academy of Pediatrics members in 2009 (n=1606; response=875 (55%)). Analysis was limited to 596 paediatricians who provide adolescent checkups. Questions addressed counselling and attitudes towards roles in promoting safe driving. Logistic regression assessed the relationship between counselling topics and practice characteristics. Most (89%) respondents provide some counselling about driving. Two topics commonly discussed by paediatricians were seatbelts (87%) and alcohol use (82%). Less frequently discussed were: cell phones (47%), speeding (43%), and dangers of transporting teen passengers (41%). Topics rarely discussed were: night driving (21%), graduated driver licensing laws (13%), safe cars (9%), driver education (9%), fatigue (25%), and parental limit setting (23%). Only 10% ever recommend a parent-teen driver agreement. Paediatricians who had a patient injured or killed in an MVC were more likely to discuss night driving (OR=2.86). Physicians caring for a high proportion of adolescents (OR=1.83) or patients with private insurance (OR=1.85) counsel more about the risks of driving with teen passengers. Paediatricians in the USA support counselling on teen driving during routine office visits, but omit many important risk factors. Few recommend parent-teen driver agreements. Methods that help clinicians efficiently and effectively counsel families about teen driving should be developed.

Three Toxic Heavy Metals in Open-Angle Glaucoma with Low-Teen and High-Teen Intraocular Pressure: A Cross-Sectional Study from South Korea.

Directory of Open Access Journals (Sweden)

Si Hyung Lee

Full Text Available To investigate the association between heavy metal levels and open-angle glaucoma (OAG with low- and high-teen baseline intraocular pressure (IOP using a population-based study design.This cross-sectional study included 5,198 participants older than 19 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES from 2008 to 2012 and had blood heavy metal levels available. The OAG with normal baseline IOP (IOP ≤ 21 mmHg subjects were stratified into low-teen OAG (baseline IOP ≤ 15 mmHg and high-teen OAG (15 mmHg < baseline IOP ≤ 21 mmHg, and the association between blood lead, mercury, and cadmium levels and glaucoma prevalence was assessed for low- and high-teen OAG.The adjusted geometric mean of blood cadmium levels was significantly higher in subjects with low-teen OAG than that of the non-glaucomatous group (P = 0.028, whereas there were no significant differences in blood lead and mercury levels. After adjusting for potential confounders, the low-teen OAG was positively associated with log-transformed blood cadmium levels (OR, 1.41; 95% confidence interval (CI, 1.03-1.93; P = 0.026. For high-teen OAG, log-transformed blood levels of the three heavy metals were not associated with disease prevalence. The association between log-transformed blood cadmium levels and low-teen OAG was significant only in men (OR, 1.65; 95% CI, 1.10-2.48; P = 0.016, and not in women (OR, 1.10; 95% CI, 0.66-1.85; P = 0.709.The results of this study suggest that cadmium toxicity could play a role in glaucoma pathogenesis, particularly in men and in OAG with low-teen baseline IOP.

Determinant Factors of the Squat Jump in Sprinting and Jumping Athletes

Directory of Open Access Journals (Sweden)

González-Badillo Juan José

2017-08-01

Full Text Available The aim of this study was to assess the relationship between strength variables and maximum velocity (Vmax in the squat jump (SJ in sprinting and jumping athletes. Thirty-two sprinting and jumping athletes of national level (25.4 ± 4.5 years; 79.4 ± 6.9 kg and 180.4 ± 6.0 cm participated in the study. Vmax in the SJ showed significant relationships with peak force 1 (PF1 (r = 0.82, p ≤ 0.001, peak force 2 (PF2 (r = 0.68, p ≤ 0.001, PF2 by controlling for PF1 (r = 0.30, non-significant, the maximum rate of force development at peak force 1 (RFDmax1 (r = 0.62, p ≤ 0.001, mean RFD 1 (RFDmean1 (r = 0.48, p ≤ 0.01, mean RFD 2 (RFDmean2 (r = 0.70, p ≤ 0.001, force at RFDmax1 (r = 0.36, p ≤ 0.05, force at RFDmax2 (r = 0.83, p ≤ 0.001 and force at RFDmax2 by controlling for PF1 (r = 0.40, p ≤ 0.05. However, Vmax in the SJ was associated negatively with the ratio PF2/PF1 (r = -0.54, p ≤ 0.01, time at peak force 2 (Tp2 (r = -0.64, p ≤ 0.001 and maximum rate of force development at peak force 2 (RFDmax2 (r = -0.71, p ≤ 0.001. These findings indicate that the peak force achieved at the beginning of the movement (PF1 is the main predictor of performance in jumping, although the RFDmax values and the ratio PF2/PF1 are also variables to be taken into account when analyzing the determinant factors of vertical jumping.

Drop jumping. II. The influence of dropping height on the biomechanics of drop jumping

NARCIS (Netherlands)

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

In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce

A Jump Diffusion Model for Volatility and Duration

DEFF Research Database (Denmark)

Wei, Wei; Pelletier, Denis

by the market microstructure theory. Traditional measures of volatility do not utilize durations. I adopt a jump diffusion process to model the persistence of intraday volatility and conditional duration, and their interdependence. The jump component is disentangled from the continuous part of the price......, volatility and conditional duration process. I develop a MCMC algorithm for the inference of irregularly spaced multivariate process with jumps. The algorithm provides smoothed estimates of the latent variables such as spot volatility, jump times and jump sizes. I apply this model to IBM data and I find...... meaningful relationship between volatility and conditional duration. Also, jumps play an important role in the total variation, but the jump variation is smaller than traditional measures that use returns sampled at lower frequency....

A teen's guide to creating web pages and blogs

CERN Document Server

Selfridge, Peter; Osburn, Jennifer

2008-01-01

Whether using a social networking site like MySpace or Facebook or building a Web page from scratch, millions of teens are actively creating a vibrant part of the Internet. This is the definitive teen''s guide to publishing exciting web pages and blogs on the Web. This easy-to-follow guide shows teenagers how to: Create great MySpace and Facebook pages Build their own unique, personalized Web site Share the latest news with exciting blogging ideas Protect themselves online with cyber-safety tips Written by a teenager for other teens, this book leads readers step-by-step through the basics of web and blog design. In this book, teens learn to go beyond clicking through web sites to learning winning strategies for web design and great ideas for writing blogs that attract attention and readership.

Dehydration (For Teens)

Science.gov (United States)

... More on this topic for: Teens What's a Healthy Alternative to Water? Compulsive Exercise IV (Video) Sports Center Caffeine Energy Drinks and Food Bars: Power or Hype? Gastrointestinal Infections and Diarrhea A Guide ...

Undular Hydraulic Jump

Directory of Open Access Journals (Sweden)

Oscar Castro-Orgaz

2015-04-01

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

Linking Changes in Contraceptive Use to Declines in Teen Pregnancy Rates

Directory of Open Access Journals (Sweden)

Jennifer Manlove

2015-12-01

Full Text Available Using a unique microsimulation tool, Teen FamilyScape, the present study explores how changes in the mix of contraceptive methods used by teens contributed to the decline in the U.S. teen pregnancy rate between 2002 and 2010. Results indicate that changes in contraceptive use contributed to approximately half of the decline in the teen pregnancy rate during this time period (48% and that a little more than half of this “contraceptive effect” was due to an increase in teen condom use (58%. The remaining share of the contraceptive effect can be attributed to an increase in the use of more effective hormonal (pill, patch, ring and long-acting reversible contraceptive (LARC/injectable methods (Intrauterine Devices (IUD, implant and injectable. Results from an additional counterfactual analysis suggest that the contraceptive effect was driven by the fact that the percentage of teens using no birth control fell during the study time period, rather than by the fact that some teens switched from less effective methods (condoms to more effective hormonal and LARC/injectable methods. However, very high typical use failure rates for teen condom users suggest the need for a two-pronged approach for continuing reductions in teen pregnancy for sexually active teens: first, targeting the youth most at risk of not using contraception and helping them choose contraception, and second, increasing the effectiveness of method use among existing contraceptors.

College-Bound Teens' Decisions about the Transition to Sex: Negotiating Competing Norms.

Science.gov (United States)

Sennott, Christie; Mollborn, Stefanie

2011-06-01

The normative influence of parents, close friends, and other peers on teens' sexual behavior has been well documented. Yet, we still know little about the processes through which these oftentimes competing norms impact teens' own sexual norms and behaviors. Drawing on qualitative data from 47 interviews conducted with college-bound teens, we investigate the processes through which perceived parental, close friend, and other peer norms about sex influenced teens' decisions about whether and when to have sex. Although virtually all teens perceived that most of their peers were having sex and that parents were almost universally against teen sex, some teens had sex and others did not. Our findings demonstrate that teens who remained virgins and those who were sexually active during high school often negotiated different sets of competing norms. Differences in understandings of age norms, in close friends' sexual norms and behaviors, and in communication about sex with parents, close friends and other peers were related to different levels of sexual behavior for teens who otherwise shared many similarities in social location (e.g.. class, race, and educational status). While virgins reported an individualized process of deciding whether they were ready for sex, we find that their behavior fits within a traditional understanding of an age norm because of the emphasis on avoiding negative sanctions. Sexually experienced teens, on the other hand, explicitly reported abiding by a group age norm that prescribed sex as normal during high school. Finally, parents' normative objections to teen sex - either moral or practical - and the ways they communicated with their teen about sex had important influence on teens' own sexual norms and behaviors during high school.

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

Science.gov (United States)

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

2017-04-15

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

Tests for nonrandomness in quantum jumps

International Nuclear Information System (INIS)

Berkeland, D.J.; Raymondson, D.A.; Tassin, V.M.

2004-01-01

In a fundamental test of quantum mechanics, we have observed 228 000 quantum jumps of a single trapped and laser cooled 88 Sr + ion. This represents a statistical increase of two orders of magnitude over previous similar analyses of quantum jumps. Compared to other searches for nonrandomness in quantum-mechanical processes, using quantum jumps simplifies the interpretation of data by eliminated multiparticle effects and providing near-unit detection efficiency of transitions. We measure the fractional reduction in the entropy of information to be -4 when the value of any interval between quantum jumps is known. We also find that the number of runs of successively increasing or decreasing interval times agrees with the theoretically expected values. Furthermore, we analyze 238 000 quantum jumps from two simultaneously confined ions and find that the number of apparently coincidental transitions is as expected. Finally, we observe 8400 spontaneous decays of two simultaneously trapped ions and find that the number of apparently coincidental decays from the metastable state agrees with the expected value. We find no evidence for short- or long-term correlations in the intervals of the quantum jumps or in the decay of the quantum states, in agreement with quantum theory

Biomechanical Analysis of the Jump Shot in Basketball

Directory of Open Access Journals (Sweden)

Struzik Artur

2014-10-01

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

Jump-Down Performance Alterations after Space Flight

Science.gov (United States)

Reschke, M. F.; Kofman, I. S.; Cerisano, J. M.; Fisher, E. A.; Peters, B. T.; Miller, C. A.; Harm, D. L.; Bloomberg, J. J.

2011-01-01

INTRODUCTION: Successful jump performance requires functional coordination of visual, vestibular, and somatosensory systems, which are affected by prolonged exposure to microgravity. Astronauts returning from space flight exhibit impaired ability to coordinate effective landing strategies when jumping from a platform to the ground. This study compares jump strategies used by astronauts before and after flight, changes to those strategies within a test session, and recoveries in jump-down performance parameters across several postflight test sessions. These data were obtained as part of an ongoing interdisciplinary study (Functional Task Test, FTT) designed to evaluate both astronaut postflight functional performance and related physiological changes. METHODS: Seven astronauts from short-duration (Shuttle) and three from long-duration (International Space Station) flights performed 3 two-footed jumps from a platform 30 cm high onto a force plate that measured the ground reaction forces and center-of-pressure displacement from the landings. Neuromuscular activation data were collected from the medial gastrocnemius and anterior tibialis of both legs using surface electromyography electrodes. Two load cells in the platform measured the load exerted by each foot during the takeoff phase of the jump. Data were collected in 2 preflight sessions, on landing day (Shuttle only), and 1, 6, and 30 days after flight. RESULTS: Postural settling time was significantly increased on the first postflight test session and many of the astronauts tested were unable to maintain balance on their first jump landing but recovered by the third jump, showing a learning progression in which performance improvements could be attributed to adjustments in takeoff or landing strategy. Jump strategy changes were evident in reduced air time (time between takeoff and landing) and also in increased asymmetry in foot latencies on takeoff. CONCLUSIONS: The test results revealed significant decrements

Media and Sex: Perspectives from Hispanic Teens

Science.gov (United States)

Johnston Polacek, Georgia N. L.; Rojas, Viviana; Levitt, Steven; Mika, Virginia Seguin

2006-01-01

Little is known about Hispanic teens' sexual knowledge, attitudes and behaviors and their relationship to media influences. Information about this relationship could contribute to an understanding of the early onset of sexual behavior and early teen pregnancy. This paper reports preliminary findings from a pilot project conducted to determine…

Appendicitis in Teens

Science.gov (United States)

... Issues Listen Español Text Size Email Print Share Appendicitis in Teens Page Content Article Body Early adolescence ... it has no known function. Symptoms that Suggest Appendicitis may Include: Persistent abdominal pain that migrates from ...

Recent changes in the trends of teen birth rates, 1981-2006.

Science.gov (United States)

Wingo, Phyllis A; Smith, Ruben A; Tevendale, Heather D; Ferré, Cynthia

2011-03-01

To explore trends in teen birth rates by selected demographics. We used birth certificate data and joinpoint regression to examine trends in teen birth rates by age (10-14, 15-17, and 18-19 years) and race during 1981-2006 and by age and Hispanic origin during 1990-2006. Joinpoint analysis describes changing trends over successive segments of time and uses annual percentage change (APC) to express the amount of increase or decrease within each segment. For teens younger than 18 years, the decline in birth rates began in 1994 and ended in 2003 (APC: -8.03% per year for ages 10-14 years; APC: -5.63% per year for ages 15-17 years). The downward trend for 18- and 19-year-old teens began earlier (1991) and ended 1 year later (2004) (APC: -2.37% per year). For each study population, the trend was approximately level during the most recent time segment, except for continuing declines for 18- and 19-year-old white and Asian/Pacific Islander teens. The only increasing trend in the most recent time segment was for 18- and 19-year-old Hispanic teens. During these declines, the age distribution of teens who gave birth shifted to slightly older ages, and the percentage whose current birth was at least their second birth decreased. Teen birth rates were generally level during 2003/2004-2006 after the long-term declines. Rates increased among older Hispanic teens. These results indicate a need for renewed attention to effective teen pregnancy prevention programs in specific populations. Copyright © 2011. Published by Elsevier Inc.

[Effects of Reactive Jump Training in Handball Players Regarding Jump Height and Power Development in the Triceps Surae Muscle].

Science.gov (United States)

Rensing, N; Westermann, A; Möller, D; von Piekartz, H

2015-12-01

Studies have shown changes in the technical and physical demands in modern handball. The game has increased considerably in speed, power and dynamics. Jump training has, therefore, become ever more important in the training of the athletes. These developments contribute to the fact that handball is now one of the most injury-prone types of sport, with the lower extremities being most frequently affected. Reactive jump training is not only used in training by now, but also increasingly in injury prevention. The aim of this study was to investigate the effectiveness of reactive jump training with handball players. 21 regional league handball players were randomly divided into an intervention group (n = 12) and a control group (n = 9). The intervention group completed a six-week reactive jump training programme while the control group went through a non-specific training programme. Jump height (squat and counter movement jump), isokinetic and isometric maximum power as well as muscle activity served as measuring parameters. A comparison of the intervention and control groups revealed that the reactive jump training led to significant improvements in jump height. The isometric and isokinetic maximum power measurements and the electromyographic activities of the triceps surae muscle demonstrated an improvement in the values within the intervention group. However, this improvement was not significant compared with the control group. Likewise both jumps correlated with the muscle activity of the soleus muscle as shown by electromyography. A moderate correlation was noticed between the isokinetic maximum power measurement and the electromyographic activity of the soleus and gastrocnemius medialis muscles. Furthermore, the correlations of the isometric and isokinetic maximum power meas-urements resulted in a strong correlation coefficient. This study revealed a significant increase in jump height after reactive jump training. There was no significant difference in

Parent's Guide to Surviving the Teen Years

Science.gov (United States)

... have about bodies, such as the differences between boys and girls and where babies come from. But don't ... together, and we'll come out of it — together! Reviewed by: Steven Dowshen, MD Date reviewed: January ... Problems in Teens Helping Teens Learn to Drive Talking to Your Child About Puberty ...

Body Mass Index: Calculator for Child and Teen

Science.gov (United States)

... Healthy Weight Sample Link BMI Percentile Calculator for Child and Teen English Version Language: English Español (Spanish) ... and Weight Accurately At Home BMI Calculator for Child and Teen ( English | Metric ) 1. Birth Date : Month: ...

Driving characteristics of teens with attention deficit hyperactivity and autism spectrum disorder.

Science.gov (United States)

Classen, Sherrilene; Monahan, Miriam; Wang, Yanning

2013-01-01

Vehicle crashes are a leading cause of death among teens. Teens with attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), or both (ADHD-ASD) may have a greater crash risk. We examined the between-groups demographic, clinical, and predriving performance differences of 22 teens with ADHD-ASD (mean age = 15.05, standard deviation [SD] = 0.95) and 22 healthy control (HC) teens (mean age = 14.32, SD = 0.72). Compared with HC teens, the teens with ADHD-ASD performed more poorly on right-eye visual acuity, selective attention, visual-motor integration, cognition, and motor performance and made more errors on the driving simulator pertaining to visual scanning, speed regulation, lane maintenance, adjustment to stimuli, and total number of driving errors. Teens with ADHD-ASD, compared with HC teens, may have more predriving deficits and as such require the skills of a certified driving rehabilitation specialist to assess readiness to drive. Copyright © 2013 by the American Occupational Therapy Association, Inc.

Teen financial literacy evaluated to develop outreach materials

OpenAIRE

Varcoe, Karen; Peterson, Shirley; Go, Charles; Johns, Margaret; René-Fitch, Paula; Powell, Carol; Costello, Connie

2002-01-01

Teenagers have access to and spend a great deal of money each year, yet research indicates that their financial literacy is low. Many curricula for teaching money management exist, but we do not know if we are teaching teens what they want to know in a way that they want to learn. This study, conducted by the Money 2000+ for Teens Workgroup of the UC Division of Agriculture and Natural Resources, sought to find out what teens want to know about financial management. Questionnaires were admini...

Pressure Jumps during Drainage in Macroporous Soils

DEFF Research Database (Denmark)

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

2018-01-01

Tensiometer readings obtained at high resolution during drainage of structured soil columns revealed pressure jumps with long range correlations and burst sequences with a hierarchical structure. The statistical properties of jumps are similar to Haines jumps described in invasion percolation...... processes at pore scale, but they are much larger in amplitude and duration. Pressure jumps can result from transient redistribution of water potential in internal regions of soil and can be triggered during drainage by capillary displacements at the scale of structural pores....

Teen Drivers' Perceptions of Inattention and Cell Phone Use While Driving.

Science.gov (United States)

McDonald, Catherine C; Sommers, Marilyn S

2015-01-01

Inattention to the roadway, including cell phone use while driving (cell phone calls, sending and reading texts, mobile app use, and Internet use), is a critical problem for teen drivers and increases risk for crashes. Effective behavioral interventions for teens are needed in order to decrease teen driver inattention related to cell phone use while driving. However, teens' perceptions of mobile device use while driving is a necessary component for theoretically driven behavior change interventions. The purpose of this study was to describe teen drivers' perceptions of cell phone use while driving in order to inform future interventions to reduce risky driving. We conducted 7 focus groups with a total of 30 teen drivers, ages 16-18, licensed for ≤ 1 year in Pennsylvania. The focus group interview guide and analysis were based on the Theory of Planned Behavior, identifying the attitudes, perceived behavioral control, and norms about inattention to the roadway. Directed descriptive content analysis was used to analyze the focus group interviews. All focus groups were coded by 2 research team members and discrepancies were reconciled. Themes were developed based on the data. Teens had a mean age of 17.39 (SD = 0.52), mean length of licensure of 173.7 days (SD = 109.2; range 4-364), were 50% male and predominately white (90%) and non-Hispanic (97%). From the focus group data, 3 major themes emerged: (1) Recognizing the danger but still engaging; (2) Considering context; and (3) Formulating safer behaviors that might reduce risk. Despite recognizing that handheld cell phone use, texting, and social media app use are dangerous and distracting while driving, teens and their peers often engaged in these behaviors. Teens described how the context of the situation contributed to whether a teen would place or answer a call, write or respond to a text, or use a social media app. Teens identified ways in which they controlled their behaviors, although some still drew

Jump Squat is More Related to Sprinting and Jumping Abilities than Olympic Push Press.

Science.gov (United States)

Loturco, I; Kobal, R; Maldonado, T; Piazzi, A F; Bottino, A; Kitamura, K; Abad, C C C; Pereira, L A; Nakamura, F Y

2017-07-01

The aim of this study was to test the relationships between jump squat (JS) and Olympic push press (OPP) power outputs and performance in sprint, squat jump (SJ), countermovement jump (CMJ) and change of direction (COD) speed tests in elite soccer players. 27 athletes performed a maximum power load test to determine their bar mean propulsive power (MPP) and bar mean propulsive velocity (MPV) in the JS and OPP exercises. Magnitude-based inference was used to compare the exercises. The MPV was almost certainly higher in the OPP than in the JS. The MPP relative to body mass (MPP REL) was possibly higher in the OPP. Only the JS MPP REL presented very large correlations with linear speed ( r> 0.7, for speed in 5, 10, 20 and 30 m) and vertical jumping abilities ( r> 0.8, for SJ and CMJ), and moderate correlation with COD speed ( r= 0.45). Although significant (except for COD), the associations between OPP outcomes and field-based measurements (speed, SJ and CMJ) were all moderate, ranging from 0.40 to 0.48. In a group composed of elite soccer players, the JS exercise is more associated with jumping and sprinting abilities than the OPP. Longitudinal studies are needed to confirm if these strong relationships imply superior training effects in favor of the JS exercise. © Georg Thieme Verlag KG Stuttgart · New York.

Hemophilia (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Hemophilia KidsHealth / For Teens / Hemophilia What's in this article? ... bruises can be a big deal. What Is Hemophilia? Hemophilia is a disease that prevents blood from ...

Endometriosis (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Endometriosis KidsHealth / For Teens / Endometriosis What's in this article? ... doctor thought Anne might have endometriosis. What Is Endometriosis? When a woman has endometriosis, tissue that looks ...

Novice teen driving : education and training administrative standards.

Science.gov (United States)

2009-10-09

The Novice Teen Driver Education and Training Administrative Standards set forth in this document serve to guide all novice teen driver education and training programs in States striving to provide quality, consistent driver education and training. W...

Teen and Parent Perceptions of a Secondary School Family Course

Science.gov (United States)

Stonely, Heather M.; Klein, Shirley R.

2004-01-01

Adolescent and parent focus groups were conducted to do a needs assessment and discover possible topics for a secondary school family class. Results included identifying teen and parent family-related needs and societal concerns; discovering where teens currently learn about family life; and receiving teen and parent feedback about a proposed…

Hydraulic jumps in a channel

DEFF Research Database (Denmark)

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

2009-01-01

We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected......'s mixing-length theory with a mixing length that is proportional to the height of the fluid layer. Using averaged boundary-layer equations, taking into account the friction with the channel walls and the eddy viscosity, the flow both upstream and downstream of the jump can be understood. For the downstream...... subcritical flow, we assume that the critical height is attained close to the channel outlet. We use mass and momentum conservation to determine the position of the jump and obtain an estimate which is in rough agreement with our experiment. We show that the averaging method with a varying velocity profile...

Option Valuation with Observable Volatility and Jump Dynamics

DEFF Research Database (Denmark)

Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

Under very general conditions, the total quadratic variation of a jump-diffusion process can be decomposed into diffusive volatility and squared jump variation. We use this result to develop a new option valuation model in which the underlying asset price exhibits volatility and jump intensity...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...

Option Valuation with Observable Volatility and Jump Dynamics

DEFF Research Database (Denmark)

Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

2015-01-01

Under very general conditions, the total quadratic variation of a jump-diffusion process can be decomposed into diffusive volatility and squared jump variation. We use this result to develop a new option valuation model in which the underlying asset price exhibits volatility and jump intensity...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...

DESIGN OF A FAST CHROMATICITY JUMP IN RHIC

International Nuclear Information System (INIS)

MONTAG, C.; KEWISCH, J.; BRUNO, D.; GANETIS, G.; LOUIE, W.

2003-01-01

During transition crossing in the .Relativistic Heavy Ion Collider (RHIC), chromaticities have to change sign. This sign change is partially accomplished by the γ t quadrupole jump; however, the resulting chromaticity jump is only Δξ x = 2.1 in the horizontal and Δξ y = 2.4 in the vertical plane. To increase the jump height, a dedicated chromaticity jump scheme has been designed, consisting of fast power supplies connected to six sextupoles per ring, which is capable of providing a chromaticity jump of Δξ = 6

Stomachaches (For Teens)

Science.gov (United States)

... to help people figure out what's behind their stress — and then provide advice on how to fix problems or handle them better. What You Can Do The good news is belly pain isn't usually serious in teens. ...

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

Science.gov (United States)

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

2015-01-01

Selection among alternative theoretical models given an observed dataset is an important challenge in many areas of physics and astronomy. Reversible-jump Markov chain Monte Carlo (RJMCMC) is an extremely powerful technique for performing Bayesian model selection, but it suffers from a fundamental difficulty and it requires jumps between model parameter spaces, but cannot efficiently explore both parameter spaces at once. Thus, a naive jump between parameter spaces is unlikely to be accepted in the Markov chain Monte Carlo (MCMC) algorithm and convergence is correspondingly slow. Here, we demonstrate an interpolation technique that uses samples from single-model MCMCs to propose intermodel jumps from an approximation to the single-model posterior of the target parameter space. The interpolation technique, based on a kD-tree data structure, is adaptive and efficient in modest dimensionality. We show that our technique leads to improved convergence over naive jumps in an RJMCMC, and compare it to other proposals in the literature to improve the convergence of RJMCMCs. We also demonstrate the use of the same interpolation technique as a way to construct efficient ‘global’ proposal distributions for single-model MCMCs without prior knowledge of the structure of the posterior distribution, and discuss improvements that permit the method to be used in higher dimensional spaces efficiently. PMID:26543580

CDC Vital Signs: Preventing Pregnancies in Younger Teens

Science.gov (United States)

... Having a mutually respectful and honest relationship. Using birth control if they have sex and a condom every time. Know where their teens are and what they are doing, particularly after school. Be aware of their teen's use of social ...

Sexual Risk Behavior: HIV, STD, & Teen Pregnancy Prevention

Science.gov (United States)

... A-Glance Project Connect Sexual Health STD Teen Pregnancy Sexual Risk Behaviors: HIV, STD, & Teen Pregnancy Prevention Recommend on Facebook Tweet ... their risk for HIV , other STDs , and unintended pregnancy . The National HIV/AIDS Strategy calls for all Americans to be ...

Getting Started with Hibernate 3

CERN Document Server

Elliott, James

2008-01-01

Hibernate has clearly arrived. Are you ready to benefit from its simple way of working with relational databases as Java objects? This PDF updates the introductory material from the award-winning Hibernate: A Developer's Notebook to teach you how to jump right in and get productive with the current release of Hibernate. You'll be walked through the ins and outs of setting up Hibernate and some related tools that make it easier to use--and that may give you new ideas about how to store information in your Java programs. In short, this PDF gives you exactly the information you need to start u

Rural parents' communication with their teen-agers about sexual issues.

Science.gov (United States)

Jordan, T R; Price, J H; Fitzgerald, S

2000-10-01

This survey assessed rural parents' (n = 374) perceptions of the characteristics, content, and comfort level of discussions about sexual issues with their teens. Almost all parents (94%) reported they had talked with their teens about sex. Two-thirds (65%) reported being comfortable talking with their teens about sexual issues. From a list of 17 potential topical areas in sexual communication, parents were most likely to discuss with their teens the responsibilities of being a parent (46%), sexually transmitted diseases (40%), dating behavior (37%), and not having sex until marriage (36%). Most parents (80%) believed that the majority of sexuality education should be provided by the family and supplemented by outside organizations, preferably schools. Almost all parents (92%) believed sexuality education should include information on birth control methods including condoms. Almost two of three parents (64%) believed schools should begin teaching sexuality education before students reach seventh grade. Parents (52%) claimed they could best be helped in communicating with their teens by receiving a regular newsletter regarding teen sexual issues.

Volatility jumps and their economic determinants

DEFF Research Database (Denmark)

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

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

How quick is a quantum jump?

International Nuclear Information System (INIS)

Schulman, L.S.

1997-01-01

Although the only time scale one ordinarily associates with a quantum transition is its lifetime, observations of ''quantum jumps'' in recent years show that the actual transition time is much shorter. I define a ''jump time'' as the time scale such that perturbations occurring at intervals of this duration affect the decay. In terms of the ''Zeno time'' (related to the second moment of the Hamiltonian) the jump time is τ J is identical to τ 2 Z /τ L . Corroboration is given. I also show that observing the ''jumping'' will not seriously affect the system lifetime, but will affect the linewidth. This is consistent with Bohr's ideas on measurement as well as with a heuristic time-energy uncertainty principle. (author)

Depression (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Depression KidsHealth / For Teens / Depression What's in this article? ... Yourself Print en español Depresión Regular Sadness vs. Depression It's natural to feel sad, down, or discouraged ...

Knee Muscular Control During Jump Landing in Multidirections.

Science.gov (United States)

Sinsurin, Komsak; Vachalathiti, Roongtiwa; Jalayondeja, Wattana; Limroongreungrat, Weerawat

2016-06-01

Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direction jump landing. Eighteen male athletes performed the jump-landing test in four directions: forward (0°), 30° diagonal, 60° diagonal, and lateral (90°). Muscles tested were vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), and biceps femoris (BF). A Vicon(TM) 612 workstation collected the kinematic data. An electromyography was synchronized with the Vicon(TM) Motion system to quantify dynamic muscle function. Repeated measure ANOVA was used to analyze the data. Jump-landing direction significantly influenced (P jump landing. A higher risk of knee injury might occur during lateral jump landing than forward and diagonal directions. Athletes should have more practice in jump landing in lateral direction to avoid injury. Landing technique with high knee flexion in multi-directions should be taught to jumpers for knee injury prevention.

Emotionally Troubled Teens' Help-Seeking Behaviors: An Evaluation of Surviving the Teens® Suicide Prevention and Depression Awareness Program

Science.gov (United States)

Strunk, Catherine M.; Sorter, Michael T.; Ossege, Julianne; King, Keith A.

2014-01-01

Many school-based suicide prevention programs do not show a positive impact on help-seeking behaviors among emotionally troubled teens despite their being at high risk for suicide. This study is a secondary analysis of the Surviving the Teens® program evaluation to determine its effect on help-seeking behaviors among troubled youth. Results showed…

Diploma Attainment among Teen Mothers. Fact Sheet. Publication #2010-01

Science.gov (United States)

Perper, Kate; Peterson, Kristen; Manlove, Jennifer

2010-01-01

Recently released government data show that in 2006, the U.S. teen birth rate began to increase, marking the end of a 14-year period of decline. More specifically, these data show that between 2005 and 2007, the teen birth rate climbed five percent. This trend reversal is a cause for concern, given the negative consequences of teen childbearing…

A review on the basketball jump shot.

Science.gov (United States)

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

2015-06-01

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

Determination of K shell absorption jump factors and jump ratios of 3d transition metals by measuring K shell fluorescence parameters.

Science.gov (United States)

Kaçal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

2015-01-01

Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature. Copyright © 2014 Elsevier Ltd. All rights reserved.

A locust-inspired miniature jumping robot.

Science.gov (United States)

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

2015-11-25

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

Designing feedback to mitigate teen distracted driving: A social norms approach.

Science.gov (United States)

Merrikhpour, Maryam; Donmez, Birsen

2017-07-01

The purpose of this research is to investigate teens' perceived social norms and whether providing normative information can reduce distracted driving behaviors among them. Parents are among the most important social referents for teens; they have significant influences on teens' driving behaviors, including distracted driving which significantly contributes to teens' crash risks. Social norms interventions have been successfully applied in various domains including driving; however, this approach is yet to be explored for mitigating driver distraction among teens. Forty teens completed a driving simulator experiment while performing a self-paced visual-manual secondary task in four between-subject conditions: a) social norms feedback that provided a report at the end of each drive on teens' distracted driving behavior, comparing their distraction engagement to their parent's, b) post-drive feedback that provided just the report on teens' distracted driving behavior without information on their parents, c) real-time feedback in the form of auditory warnings based on eyes of road-time, and d) no feedback as control. Questionnaires were administered to collect data on these teens' and their parents' self-reported engagement in driver distractions and the associated social norms. Social norms and real-time feedback conditions resulted in significantly smaller average off-road glance duration, rate of long (>2s) off-road glances, and standard deviation of lane position compared to no feedback. Further, social norms feedback decreased brake response time and percentage of time not looking at the road compared to no feedback. No major effect was observed for post-drive feedback. Questionnaire results suggest that teens appeared to overestimate parental norms, but no effect of feedback was found on their perceptions. Feedback systems that leverage social norms can help mitigate driver distraction among teens. Overall, both social norms and real-time feedback induced

Cerebral Palsy Checklist: Teens & Young Adult (13 to 21)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Cerebral Palsy Checklist: Teens & Young Adults KidsHealth / For Parents / Cerebral Palsy Checklist: Teens & Young Adults What's in this article? ...

Determination of K shell absorption jump factors and jump ratios of 3d transition metals by measuring K shell fluorescence parameters

International Nuclear Information System (INIS)

Kaçal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

2015-01-01

Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature. - Highlights: • This work regard the K shell absorption jump ratios and jump factors of Ti, Cr, Fe, Co, Ni and Cu. • This paper presents the first measurement of these parameters using the experimental K shell fluorescence parameters. • A good agreement was found between experimental and theoretical values. • The EDXRF technique was suitable, precise and reliable for the measurement of these atomic parameters

Does trampoline or hard surface jumping influence lower extremity alignment?

Science.gov (United States)

Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby

2017-12-01

[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations.

The Rate of Cyber Dating Abuse among Teens and How It Relates to Other Forms of Teen Dating Violence

Science.gov (United States)

Zweig, Janine M.; Dank, Meredith; Yahner, Jennifer; Lachman, Pamela

2013-01-01

To date, little research has documented how teens might misuse technology to harass, control, and abuse their dating partners. This study examined the extent of cyber dating abuse--abuse via technology and new media--in youth relationships and how it relates to other forms of teen dating violence. A total of 5,647 youth from ten schools in three…

Teen Pregnancy Risk Factors Among Young Women of Diverse Sexual Orientations.

Science.gov (United States)

Charlton, Brittany M; Roberts, Andrea L; Rosario, Margaret; Katz-Wise, Sabra L; Calzo, Jerel P; Spiegelman, Donna; Austin, S Bryn

2018-04-01

Young women who are sexual minorities (eg, bisexual and lesbian) are approximately twice as likely as those who are heterosexual to have a teen pregnancy. Therefore, we hypothesized that risk factors for teen pregnancy would vary across sexual orientation groups and that other potential risk factors exist that are unique to sexual minorities. We used multivariable log-binomial models gathered from 7120 young women in the longitudinal cohort known as the Growing Up Today Study to examine the following potential teen pregnancy risk factors: childhood maltreatment, bullying victimization and perpetration, and gender nonconformity. Among sexual minorities, we also examined the following: sexual minority developmental milestones, sexual orientation-related stress, sexual minority outness, and lesbian, gay, and bisexual social activity involvement. Childhood maltreatment and bullying were significant teen pregnancy risk factors among all participants. After adjusting for childhood maltreatment and bullying, the sexual orientation-related teen pregnancy disparities were attenuated; these risk factors explained 45% of the disparity. Among sexual minorities, reaching sexual minority developmental milestones earlier was also associated with an increased teen pregnancy risk. The higher teen pregnancy prevalence among sexual minorities compared with heterosexuals in this cohort was partially explained by childhood maltreatment and bullying, which may, in part, stem from sexual orientation-related discrimination. Teen pregnancy prevention efforts that are focused on risk factors more common among young women who are sexual minorities (eg, childhood maltreatment, bullying) can help to reduce the existing sexual orientation-related teen pregnancy disparity. Copyright © 2018 by the American Academy of Pediatrics.

Isokinetic trunk muscle performance in pre-teens and teens with and without back pain.

Science.gov (United States)

Bernard, J-C; Boudokhane, S; Pujol, A; Chaléat-Valayer, E; Le Blay, G; Deceuninck, J

2014-02-01

To assess with an isokinetic dynamometer the force and endurance of the spinal flexor and extensor muscles in pre-teens or teens aged 11 to 13 and 14 to 16 years with and without low back pain (LBP). The control group and the LBP group were homogeneous in terms of age, weight, height and Body Mass Index (BMI). Assessment was carried out with the isokinetic dynamometer Cybex Norm®. The spinal flexors and extensors were explored concentrically at speeds of 60°, 90° and 120°/sec. The parameters chosen were: maximal moment of force (MMF), mean power (MP), total work (TW), F/E ratios (between the flexors and the extensors for the aforesaid parameters). In the LBP groups, clinical information (pain, extensibility of the spinal and sub-pelvic muscles, sports practice) and sagittal radiological data were all measured. While no significant difference in isokinetic performance was found between asymptomatic and LBP children in the 11-to-13-year-old group, the isokinetic performances of the LBP children were influenced positively by BMI value, number of hours of physical activity and radiologic value of the lumbar lordosis. As regards these pre-teens, assessment with an isokinetic dynamometer does not highlight muscle characteristics that might explain LBP occurrence. As regards the 14-to-16-year-old group, muscle strength has been found to be correlated with age. LBP teens were showed to have weaker extensors and stronger flexors than the healthy teens. It is with regard to this age group that assessment with an isokinetic dynamometer clearly yields interesting results. Since we have yet to standardize our evaluation criteria (working speed, number of trials…), it is difficult to compare our results with those reported in the literature. This is a preliminary study involving a relatively low number of patients. That said, given the fact that numerous parameters are connected with the age and height of the subjects, assessment with an isokinetic dynamometer can be

Analyzing and Identifying Teens' Stressful Periods and Stressor Events From a Microblog.

Science.gov (United States)

Li, Qi; Xue, Yuanyuan; Zhao, Liang; Jia, Jia; Feng, Ling

2017-09-01

Increased health problems among adolescents caused by psychological stress have aroused worldwide attention. Long-standing stress without targeted assistance and guidance negatively impacts the healthy growth of adolescents, threatening the future development of our society. So far, research focused on detecting adolescent psychological stress revealed from each individual post on microblogs. However, beyond stressful moments, identifying teens' stressful periods and stressor events that trigger each stressful period is more desirable to understand the stress from appearance to essence. In this paper, we define the problem of identifying teens' stressful periods and stressor events from the open social media microblog. Starting from a case study of adolescents' posting behaviors during stressful school events, we build a Poisson-based probability model for the correlation between stressor events and stressful posting behaviors through a series of posts on Tencent Weibo (referred to as the microblog throughout the paper). With the model, we discover teens' maximal stressful periods and further extract details of possible stressor events that cause the stressful periods. We generalize and present the extracted stressor events in a hierarchy based on common stress dimensions and event types. Taking 122 scheduled stressful study-related events in a high school as the ground truth, we test the approach on 124 students' posts from January 1, 2012 to February 1, 2015 and obtain some promising experimental results: (stressful periods: recall 0.761, precision 0.737, and F 1 -measure 0.734) and (top-3 stressor events: recall 0.763, precision 0.756, and F 1 -measure 0.759). The most prominent stressor events extracted are in the self-cognition domain, followed by the school life domain. This conforms to the adolescent psychological investigation result that problems in school life usually accompanied with teens' inner cognition problems. Compared with the state-of-the-art top

Teen Drinking and Driving: A Dangerous Mix. CDC Vitalsigns[TM

Science.gov (United States)

Centers for Disease Control and Prevention, 2012

2012-01-01

The percentage of teens in high school who drink and drive has decreased by more than half since 1991, but more can be done. Nearly one million high school teens drank alcohol and got behind the wheel in 2011. Teen drivers are 3 times more likely than more experienced drivers to be in a fatal crash. Drinking any alcohol greatly increases this risk…

Characteristics of Single Vehicle Crashes with a Teen Driver in South Carolina, 2005-2008.

Science.gov (United States)

Shults, Ruth A; Bergen, Gwen; Smith, Tracy J; Cook, Larry; Kindelberger, John; West, Bethany

2017-09-22

Teens' crash risk is highest in the first years of independent driving. Circumstances surrounding fatal crashes have been widely documented, but less is known about factors related to nonfatal teen driver crashes. This study describes single vehicle nonfatal crashes involving the youngest teen drivers (15-17 years), compares these crashes to single vehicle nonfatal crashes among adult drivers (35-44 years) and examines factors related to nonfatal injury producing crashes for teen drivers. Police crash data linked to hospital inpatient and emergency department data for 2005-2008 from the South Carolina Crash Outcomes Data Evaluation System (CODES) were analyzed. Nonfatal, single vehicle crashes involving passenger vehicles occurring on public roadways for teen (15-17 years) drivers were compared with those for adult (35-44 years) drivers on temporal patterns and crash risk factors per licensed driver and per vehicle miles traveled. Vehicle miles traveled by age group was estimated using data from the 2009 National Household Travel Survey. Multivariable log-linear regression analysis was conducted for teen driver crashes to determine which characteristics were related to crashes resulting in a minor/moderate injury or serious injury to at least one vehicle occupant. Compared with adult drivers, teen drivers in South Carolina had 2.5 times the single vehicle nonfatal crash rate per licensed driver and 11 times the rate per vehicle mile traveled. Teen drivers were nearly twice as likely to be speeding at the time of the crash compared with adult drivers. Teen driver crashes per licensed driver were highest during the afternoon hours of 3:00-5:59 pm and crashes per mile driven were highest during the nighttime hours of 9:00-11:59 pm. In 66% of the teen driver crashes, the driver was the only occupant. Crashes were twice as likely to result in serious injury when teen passengers were present than when the teen driver was alone. When teen drivers crashed while

Acute Improvement of Vertical Jump Performance After Isometric Squats Depends on Knee Angle and Vertical Jumping Ability.

Science.gov (United States)

Tsoukos, Athanasios; Bogdanis, Gregory C; Terzis, Gerasimos; Veligekas, Panagiotis

2016-08-01

Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016-This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p = 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p = 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p = 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p = 0.001) and 7.4 ± 1.2% (p = 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p = 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity.

Mobile Phones Bridging the Digital Divide for Teens in the US?

Directory of Open Access Journals (Sweden)

Katie Brown

2011-05-01

Full Text Available In 2009, just 27% of American teens with mobile phones reported using their devices to access the internet. However, teens from lower income families and minority teens were significantly more likely to use their phones to go online. Together, these surprising trends suggest a potential narrowing of the digital divide, offering internet access to those without other means of going online. This is an important move, as, in today’s society, internet access is central to active citizenship in general and teen citizenship in particular. Yet the cost of this move toward equal access is absorbed by those who can least afford it: Teenagers from low income households. Using survey and focus group data from a national study of “Teens and Mobile Phone Use” (released by Pew and the University of Michigan in 2010, this article helps identify and explain this and other emergent trends for teen use (as well as non-use of the internet through mobile phones.

State policy and teen childbearing: a review of research studies.

Science.gov (United States)

Beltz, Martha A; Sacks, Vanessa H; Moore, Kristin A; Terzian, Mary

2015-02-01

Teen childbearing is affected by many individual, family, and community factors; however, another potential influence is state policy. Rigorous studies of the relationship between state policy and teen birth rates are few in number but represent a body of knowledge that can inform policy and practice. This article reviews research assessing associations between state-level policies and teen birth rates, focusing on five policy areas: access to family planning, education, sex education, public assistance, and access to abortion services. Overall, several studies have found that measures related to access to and use of family planning services and contraceptives are related to lower state-level teen birth rates. These include adolescent enrollment in clinics, minors' access to contraception, conscience laws, family planning expenditures, and Medicaid waivers. Other studies, although largely cross-sectional analyses, have concluded that policies and practices to expand or improve public education are also associated with lower teen birth rates. These include expenditures on education, teacher-to-student ratios, and graduation requirements. However, the evidence regarding the role of public assistance, abortion access, and sex education policies in reducing teen birth rates is mixed and inconclusive. These conclusions must be viewed as tentative because of the limited number of rigorous studies that examine the relationship between state policy and teen birth rates over time. Many specific policies have only been analyzed by a single study, and few findings are based on recent data. As such, more research is needed to strengthen our understanding of the role of state policies in teen birth rates. Copyright © 2015 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Investigating recent trends in the U.S. teen birth rate.

Science.gov (United States)

Kearney, Melissa S; Levine, Phillip B

2015-05-01

We investigate trends in the U.S. rate of teen childbearing between 1981 and 2010, focusing specifically on the sizable decline since 1991. We focus on establishing the role of state-level demographic changes, economic conditions, and targeted policies in driving recent aggregate trends. We offer three main observations. First, the recent decline cannot be explained by the changing racial and ethnic composition of teens. Second, the only targeted policies that have had a statistically discernible impact on aggregate teen birth rates are declining welfare benefits and expanded access to family planning services through Medicaid, but these policies can account for only 12.6 percent of the observed decline since 1991. Third, higher unemployment rates lead to lower teen birth rates and can account for 16 percent of the decline in teen birth rates since the Great Recession began. Copyright © 2015 Elsevier B.V. All rights reserved.

Do breastfeeding intentions of pregnant inner-city teens and adult women differ?

Science.gov (United States)

Alexander, Ashley; O'Riordan, Mary Ann; Furman, Lydia

2010-12-01

This study compared the breastfeeding intentions and attitudes of pregnant low-income inner-city teens (age ≤19 years) and non-teens (age ≥20) to determine if age is a significant determinant of intent to breastfeed in this population. We used structured interviews to examine the feeding intentions and attitudes of consecutive healthy pregnant women receiving obstetrical care at the Women's Health Center, MacDonald Women's Hospital, Cleveland, OH (June 1-July 31, 2007). The primary outcome measure was rate of intent to breastfeed among teen versus non-teen participants. Attitudes and self-assessed knowledge regarding breastfeeding were compared between teens and non-teens, and multiple logistic regression analysis was used to examine the effect of age on breastfeeding intent. We interviewed 176 pregnant women (95% African-American, 94% single marital status, median age 22 years [range, 15-41 years], 46 [26%] teens) at a median of 27 weeks of pregnancy. There were no significant differences between teens and non-teens in race, marital status, or timing of first prenatal visit or interview. Rate of intent to breastfeed and planned duration and exclusivity of breastfeeding, as well as most measured attitudes about breastfeeding including "back to work" plans, were not significantly different between groups. Significant determinants of feeding intent included primiparity, good self-assessed knowledge about breastfeeding, and having support from the father of the baby. In a population at high risk for choosing not to breastfeed, we found no significant explanatory effect of age on breastfeeding intention, implying that an inclusive targeted breastfeeding intervention program may be effective for both teens and non-teens in a low-income inner-city population. We also found that the support of the father of the baby significantly influenced breastfeeding intent among our participants, suggesting that paternal involvement will be integral to the success of

Teen Science Cafés: A Vehicle for Scientists Seeking Broader Impacts

Science.gov (United States)

Hall, M.; Mayhew, M. A.

2015-12-01

Teen Science Cafés are a global phenomenon where scientists and teenagers engage in lively conversations about current, relevant, and intriguing science. In the past two years, Teen Café programs have been initiated in 41 sites in 18 U.S. states via the Teen Science Cafe Network, teensciencecafe.org. Other such programs are growing in the UK, eastern Africa, South Africa, and Singapore. The events are a free, informal, and low risk way for scientists to share their science with a receptive audience much focused on future careers. The success of a Café depends on the core principle that rich conversation occurs; a Café program is not a lecture series. Engaging teen participants brings out different perspectives and new dimensions to the topic; this has typically given scientists new ways of thinking about their own research! Presenting the event as a conversation and inviting the teens to bring in questions and points of view is key to fostering a dynamic Café. Scientists report that the training provided for these engagements has changed the way they talk about their science to peers, managers, and funding agencies. Teen Cafés have been shown to significantly change teens' view of the importance of science in their lives, positively influence teens' understanding of science in the news, and increase their ability and confidence to use facts to support scientific points of view. The Café events also positively influenced teens' interest in science and science careers, and revealed to them the true nature of scientific research and the interesting lives that scientists lead. Cafés are an excellent vehicle for scientists to have broader impact on the current generation of students, our future adult citizens. The Teen Science Café Network is an open community of practice committed to helping others implement Teen Cafés.

Food Safety and Nutrition Information for Kids and Teens

Science.gov (United States)

... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Resources for You Consumers Kids & Teens ... More sharing options Linkedin Pin it Email Print Food Safety & Nutrition Information for Kids and Teens Fun & ...

Teen Drivers’ Perceptions of Inattention and Cell Phone Use While Driving

Science.gov (United States)

Sommers, Marilyn S.

2015-01-01

Objective Inattention to the roadway, including cell phone use while driving (cell phone calls, sending and reading texts, mobile app use and internet use), is a critical problem for teen drivers and increases risk for crashes. Effective behavioral interventions for teens are needed in order to decrease teen driver inattention related to cell phone use while driving. However, teens’ perceptions of mobile device use while driving is a necessary component for theoretically driven behavior change interventions. The purpose of this study was to describe teen drivers’ perceptions of cell phone use while driving in order to inform future interventions to reduce risky driving. Methods We conducted seven focus groups with a total of 30 teen drivers, ages 16–18, licensed for ≤1 year in Pennsylvania. The focus group interview guide and analysis were based on the Theory of Planned Behavior, identifying the attitudes, perceived behavioral control, and norms about inattention to the roadway. Directed descriptive content analysis was used to analyze the focus group interviews. All focus groups were coded by two research team members and discrepancies were reconciled. Themes were developed based on the data. Results Teens had a mean age of 17.39 (sd 0.52), mean length of licensure of 173.7 days (sd 109.2; range 4–364), were 50% male and predominately white (90%) and non-Hispanic (97%). From the focus group data, three major themes emerged; (1) Recognizing the danger but still engaging; (2) Considering context; and (3) Formulating safer behaviors that might reduce risk. In spite of recognizing hand-held cell phone use, texting and social media app use are dangerous and distracting while driving, teens and their peers often engage in these behaviors. Teens described how the context of the situation contributed to whether a teen would place or answer a call, write or respond to a text, or use a social media app. Teens identified ways in which they controlled their

Predicting lower body power from vertical jump prediction equations for loaded jump squats at different intensities in men and women.

Science.gov (United States)

Wright, Glenn A; Pustina, Andrew A; Mikat, Richard P; Kernozek, Thomas W

2012-03-01

The purpose of this study was to determine the efficacy of estimating peak lower body power from a maximal jump squat using 3 different vertical jump prediction equations. Sixty physically active college students (30 men, 30 women) performed jump squats with a weighted bar's applied load of 20, 40, and 60% of body mass across the shoulders. Each jump squat was simultaneously monitored using a force plate and a contact mat. Peak power (PP) was calculated using vertical ground reaction force from the force plate data. Commonly used equations requiring body mass and vertical jump height to estimate PP were applied such that the system mass (mass of body + applied load) was substituted for body mass. Jump height was determined from flight time as measured with a contact mat during a maximal jump squat. Estimations of PP (PP(est)) for each load and for each prediction equation were compared with criterion PP values from a force plate (PP(FP)). The PP(est) values had high test-retest reliability and were strongly correlated to PP(FP) in both men and women at all relative loads. However, only the Harman equation accurately predicted PP(FP) at all relative loads. It can therefore be concluded that the Harman equation may be used to estimate PP of a loaded jump squat knowing the system mass and peak jump height when more precise (and expensive) measurement equipment is unavailable. Further, high reliability and correlation with criterion values suggest that serial assessment of power production across training periods could be used for relative assessment of change by either of the prediction equations used in this study.

Hydrodynamics of vertical jumping in Archer fish

Science.gov (United States)

Techet, Alexandra H.; Mendelson, Leah

2017-11-01

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

A data-driven wavelet-based approach for generating jumping loads

Science.gov (United States)

Chen, Jun; Li, Guo; Racic, Vitomir

2018-06-01

This paper suggests an approach to generate human jumping loads using wavelet transform and a database of individual jumping force records. A total of 970 individual jumping force records of various frequencies were first collected by three experiments from 147 test subjects. For each record, every jumping pulse was extracted and decomposed into seven levels by wavelet transform. All the decomposition coefficients were stored in an information database. Probability distributions of jumping cycle period, contact ratio and energy of the jumping pulse were statistically analyzed. Inspired by the theory of DNA recombination, an approach was developed by interchanging the wavelet coefficients between different jumping pulses. To generate a jumping force time history with N pulses, wavelet coefficients were first selected randomly from the database at each level. They were then used to reconstruct N pulses by the inverse wavelet transform. Jumping cycle periods and contract ratios were then generated randomly based on their probabilistic functions. These parameters were assigned to each of the N pulses which were in turn scaled by the amplitude factors βi to account for energy relationship between successive pulses. The final jumping force time history was obtained by linking all the N cycles end to end. This simulation approach can preserve the non-stationary features of the jumping load force in time-frequency domain. Application indicates that this approach can be used to generate jumping force time history due to single people jumping and also can be extended further to stochastic jumping loads due to groups and crowds.

Jump Shrug Height and Landing Forces Across Various Loads.

Science.gov (United States)

Suchomel, Timothy J; Taber, Christopher B; Wright, Glenn A

2016-01-01

The purpose of this study was to examine the effect that load has on the mechanics of the jump shrug. Fifteen track and field and club/intramural athletes (age 21.7 ± 1.3 y, height 180.9 ± 6.6 cm, body mass 84.7 ± 13.2 kg, 1-repetition-maximum (1RM) hang power clean 109.1 ± 17.2 kg) performed repetitions of the jump shrug at 30%, 45%, 65%, and 80% of their 1RM hang power clean. Jump height, peak landing force, and potential energy of the system at jump-shrug apex were compared between loads using a series of 1-way repeated-measures ANOVAs. Statistical differences in jump height (P .05). The greatest magnitudes of jump height, peak landing force, and potential energy of the system at the apex of the jump shrug occurred at 30% 1RM hang power clean and decreased as the external load increased from 45% to 80% 1RM hang power clean. Relationships between peak landing force and potential energy of the system at jump-shrug apex indicate that the landing forces produced during the jump shrug may be due to the landing strategy used by the athletes, especially at lighter loads. Practitioners may prescribe heavier loads during the jump-shrug exercise without viewing landing force as a potential limitation.

Intra-Personal and Inter-Personal Kinetic Synergies During Jumping

Directory of Open Access Journals (Sweden)

Slomka Kajetan

2015-12-01

Full Text Available We explored synergies between two legs and two subjects during preparation for a long jump into a target. Synergies were expected during one-person jumping. No such synergies were expected between two persons jumping in parallel without additional contact, while synergies were expected to emerge with haptic contact and become stronger with strong mechanical contact. Subjects performed jumps either alone (each foot standing on a separate force platform or in dyads (parallel to each other, each person standing on a separate force platform without any contact, with haptic contact, and with strong coupling. Strong negative correlations between pairs of force variables (strong synergies were seen in the vertical force in one-person jumps and weaker synergies in two-person jumps with the strong contact. For other force variables, only weak synergies were present in one-person jumps and no negative correlations between pairs of force variable for two-person jumps. Pairs of moment variables from the two force platforms at steady state showed positive correlations, which were strong in one-person jumps and weaker, but still significant, in two-person jumps with the haptic and strong contact. Anticipatory synergy adjustments prior to action initiation were observed in oneperson trials only. We interpret the different results for the force and moment variables at steady state as reflections of postural sway.

Teen Perceptions of the Promotion of Safer Sexual Practices: A Focus Group Study

Science.gov (United States)

Herrman, Judith W.; Kelley, Andrea; Haigh, Katherine M.

2017-01-01

Teens' own thoughts on fostering safe sexual practice are important perspectives in promoting adolescent sexual health yet are relatively absent in the literature. This focus group study explored teens' perceptions about the supports and challenges that exist as teens strive to engage in healthy sexual practices. Seventy-five teens participated in…

Denormalizing a Historical Problem: Teen Pregnancy, Policy, and Public Health Action

Science.gov (United States)

Kandakai, Tina L.; Smith, Leonie C. R.

2007-01-01

Objective: To explore the impact of teen-adult sexual relationships as a public health threat and the effectiveness of statutory rape laws in protecting adolescent children. Methods: A comprehensive review of current literature surrounding child abuse, teen pregnancy, and statutory rape was conducted. Results: Of one million teen girls who become…

Effects of Isometric Scaling on Vertical Jumping Performance

Science.gov (United States)

Bobbert, Maarten F.

2013-01-01

Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli’s law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations. PMID:23936494

Effects of isometric scaling on vertical jumping performance.

Directory of Open Access Journals (Sweden)

Maarten F Bobbert

Full Text Available Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli's law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations.

Vital signs: births to teens aged 15-17 years--United States, 1991-2012.

Science.gov (United States)

Cox, Shanna; Pazol, Karen; Warner, Lee; Romero, Lisa; Spitz, Alison; Gavin, Lorrie; Barfield, Wanda

2014-04-11

Teens who give birth at age 15-17 years are at increased risk for adverse medical and social outcomes of teen pregnancy. To examine trends in the rate and proportion of births to teens aged 15-19 years that were to teens aged 15-17 years, CDC analyzed 1991-2012 National Vital Statistics System data. National Survey of Family Growth (NSFG) data from 2006-2010 were used to examine sexual experience, contraceptive use, and receipt of prevention opportunities among female teens aged 15-17 years. During 1991-2012, the rate of births per 1,000 teens declined from 17.9 to 5.4 for teens aged 15 years, 36.9 to 12.9 for those aged 16 years, and 60.6 to 23.7 for those aged 17 years. In 2012, the birth rate per 1,000 teens aged 15-17 years was higher for Hispanics (25.5), non-Hispanic blacks (21.9), and American Indians/Alaska Natives (17.0) compared with non-Hispanic whites (8.4) and Asians/Pacific Islanders (4.1). The rate also varied by state, ranging from 6.2 per 1,000 teens aged 15-17 years in New Hampshire to 29.0 in the District of Columbia. In 2012, there were 86,423 births to teens aged 15-17 years, accounting for 28% of all births to teens aged 15-19 years. This percentage declined from 36% in 1991 to 28% in 2012 (pteens aged 15-17 years received formal sex education on birth control or how to say no to sex, 24% had not spoken with parents about either topic; among sexually experienced female teens, 83% reported no formal sex education before first sex. Among currently sexually active female teens (those who had sex within 3 months of the survey) aged 15-17 years, 58% used clinical birth control services in the past 12 months, and 92% used contraception at last sex; however, only 1% used the most effective reversible contraceptive methods. Births to teens aged 15-17 years have declined but still account for approximately one quarter of births to teens aged 15-19 years. These data highlight opportunities to increase younger teens exposure to interventions that delay

The AGS γt-jump system

International Nuclear Information System (INIS)

Syphers, M.J.; Ahrens, L.; van Asselt, W.; Brennan, J.M.

1994-01-01

In an attempt to generate a lossless crossing of an accelerator's transition energy, one procedure is to alter the transition energy of the accelerator quickly as the beam passes through this energy region by changing the optics of the lattice -- a so-called ''transition jump,'' or '' γt -jump'' scheme. Such a system was first implemented at CERN and later adopted at other accelerator laboratories. A scheme for the AGS was developed in 1986. A description of the AGS γt -jump system, and recent results from its commissioning are presented in this report

Nonstandard jump functions for radically symmetric shock waves

International Nuclear Information System (INIS)

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

2008-01-01

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

Health Care Factors Influencing Teen Mothers' Use Of Contraceptives in Malawi.

Science.gov (United States)

Machira, Kennedy; Palamuleni, Martin E

2017-06-01

The study seeks to examine factors associated with teen mothers' use of modern contraceptives after giving birth. The 2010 Malawi Demographic and Health Survey data was used to test the study objective. A sample of 12, 911 teen mothers aged between 10 and 18 years were extracted from 23, 020 women and were asked of contraceptive usage after first birth experiences, in which, a logistic regression model was employed to estimate correlates of contraceptive usage. The study found that 54.8% of the teen mothers are still at a risk of having a repeat teenage pregnancy due to their non-use of contraceptives. This implies that less than 50% of teen mothers use contraceptives after experiencing teen birth. It is noted that health care factors such as use of antenatal care, awareness of pregnancy complications, attainment of primary education and exposure to media predict teen mothers' use of modern contraceptives. Despite endeavours made by government to improve access to family planning, health care challenges still exist affecting women's use of contraceptives in Malawi. Ameliorating these health encounters call for wide-range approaches aimed at addressing teen birth comprehensively in order to prevent early motherhood and subsequently high fertility. None declared.

Implications of teen birth for overweight and obesity in adulthood.

Science.gov (United States)

Chang, Tammy; Choi, HwaJung; Richardson, Caroline R; Davis, Matthew M

2013-08-01

The objective of this study was to examine whether teen birth was independently associated with overweight and obesity in a US cohort. We examined whether teen birth is independently associated with overweight and obesity in a multiyear US cohort using the 2001-2010 National Health and Nutrition Examination Survey, a nationally representative cross-sectional survey of the US civilian, noninstitutionalized population. We performed multinomial logistic regression adjusting for survey cohort, age at survey, race, education, and parity. We included women 20-59 years old at the time of survey, with at least 1 live birth, not currently or recently pregnant (unweighted, n = 5220; weighted, n = 48.4 million). Our outcome measure was the effect of teen birth on subsequent overweight and obesity. In bivariate analyses, women with a teen birth were significantly more likely than women without a teen birth to be overweight (relative risk ratios [RRRs], 1.61; 95% confidence interval [CI], 1.37-1.90) or obese (RRR, 1.84; 95% CI, 1.56-2.16) at the time of the survey. In multivariate models, women with a teen birth remained significantly more likely to be overweight (adjusted RRR, 1.33; 95% CI, 1.10-1.62) or obese (adjusted RRR, 1.32; 95% CI, 1.09-1.61) than women without a teen birth. For women in the United States, giving birth as a teen is associated with subsequent overweight/obese status later in life. To inform clinical and policy interventions with the goal to improve the long-term health of teenage mothers, future studies must examine modifiable physiological and sociomedical reasons for early child-bearing and later risk of obesity. Copyright © 2013 Mosby, Inc. All rights reserved.

K-shell jump ratios and jump factors for molybdenum and silver by using 2D-geometrical configuration and a weak gamma source

International Nuclear Information System (INIS)

Francis Maria Anand, L.; Gudennavar, S.B.; Bubbly, S.G.; Joseph, Daisy

2013-01-01

The article presents a simple method of measuring K-shell absorption jump ratios and jump factors for elements in the field of X-ray spectroscopy. The K-shell jump ratios and jump factors for Molybdenum and Silver are measured by adopting 2ŏ-geometrical configuration and a weak gamma source. The characteristic K X-ray photons are excited in the targets using 32.8 keV barium X-ray photons from a weak 137 Cs radioactive source that is produced due to the internal conversion of cesium nucleus (IC). The fluorescent K X-ray photons are detected using low energy Si(Li) detector coupled to a 8k multichannel analyser. The K X-ray intensity ratios from X-ray fluorescent spectrum are measured experimentally, the total atomic attenuation cross section and the total atomic scattering cross sections are calculated using WinXcom software. The K-shell jump factor and jump ratio are computed using the measured K X-ray intensity ratios and the calculated K a , X-ray production cross section. The computed values of K-shell jump factor and jump ratio for molybdenum and silver are compared with the theoretical values and others' experimental data and are presented. The amount of uncertainty in the experimental measurement of K X-ray intensity ratios is less than 5%. Thus the 2ŏ-geometrical configuration method with weak gamma source can be an alternative simple method to measure the jump factors and the jump ratios of pure elements in the field of X-ray spectroscopy. (author)

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

Science.gov (United States)

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

2015-02-01

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

Vital Signs: Repeat Births Among Teens — United States, 2007–2010

OpenAIRE

Gavin, Lorrie; Warner, Lee; O’Neil, Mary Elizabeth; Duong, Linh M.; Marshall, Cassondra; Hastings, Philip A.; Harrison, Ayanna T.; Barfield, Wanda

2013-01-01

Background Teen childbearing has potential negative health, economic, and social consequences for mother and child. Repeat teen childbearing further constrains the mother’s education and employment possibilities. Rates of preterm and low birth weight are higher in teens with a repeat birth, compared with first births. Methods To assess patterns of repeat childbearing and postpartum contraceptive use among teens, CDC analyzed natality data from the National Vital Statistics System (NVSS) and t...

Combining Photovoice and focus groups: engaging Latina teens in community assessment.

Science.gov (United States)

Hannay, Jayme; Dudley, Robert; Milan, Stephanie; Leibovitz, Paula K

2013-03-01

Latino adolescents, especially girls, experience higher obesity rates and are more likely to be physically unfit than non-Latino white peers. Out-of-school programs to increase physical activity and fitness in older Latino teens are critical, but sustained engagement is challenging. This study combined a community-based participatory research methodology, Photovoice, with focus groups to engage Latina teens and their parents in identifying barriers to physical activity and initiating policy change actions to address them. The study investigates the effectiveness of applying Photovoice as both an evaluation tool and a leadership/advocacy intervention in a community-based obesity prevention program. Focus group data were collected between July 2009 and October 2010 and analyzed between November 2010 and July 2011. Five focus groups were held with adults (n = 41: 95% Latino) and four with teens (n = 36: 81% Latino, 10% non-Hispanic white, 9% African-American). All participants (19 teens, six adults) were Latino. Spanish-speaking staff of a community-based agency, program staff, high school guidance counselors, and a job development agency recruited participants. Teens aged 14-19 years enrolled in New Britain CT, high schools, and their parents were eligible. Data from Photovoice workshops (three with teens, two with parent-teen dyads) were collected and concurrently analyzed between July 2009 and August 2011. Teens criticized school-based physical exercise programs in favor of out-of-school exercise and career advice. Parental restrictions and work, transportation, and safety issues were cited as barriers to afterschool physical activity programs. Photovoice can empower teens and parents to address exercise barriers by promoting advocacy that leads to policy change (e.g., an out-of-school physical education option). Copyright © 2013 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

School start time effects on adolescent learning and academic performance, emotional health and behaviour.

Science.gov (United States)

Wahlstrom, Kyla L; Owens, Judith A

2017-11-01

The investigation of the relationship between the time of day that school begins and the effects it could have on students began in the mid-1990s. Since that time, many articles have been written either for the medical literature or the educational literature. This review is intended to bridge that gap by examining together the findings for both academic and health outcomes, exploring what we know and what is needed in further investigation. Teens who are sleep deficient (defined as obtaining less than 8 h per night) because of early starting time for their school are much more likely to engage in risky behaviours, such as drug, cigarette and alcohol use, have significant feelings of depression, get lower grades and are at greater risk for car crashes. Many studies of academic performance and later school start time indicate benefits, although further research is needed to understand the related mechanisms that contribute to improvements in achievement. Recent research in adolescent sleep and outcomes is being shaped by not only measuring sleep duration, but also examining the timing in which sleep occurs. Early school starting time for middle and high students has a clear, deleterious effect on their health and well being. Most recently, sleep deficit in teens is being viewed as a public health issue that needs a wider discussion about its impact and it necessitates improved public education about the sleep phase shift that occurs during adolescence.

Teens Reflect on Their Sources of Contraceptive Information

Science.gov (United States)

Jones, Rachel K.; Biddlecom, Ann E.; Hebert, Luciana; Mellor, Ruth

2011-01-01

Based on semistructured interviews with a racially and ethnically diverse sample of 58 U.S. high school students, this study examines teens' exposure to contraceptive information from a range of sources and the extent to which they trust this information. Teens report exposure to contraceptive information from many individuals and places, most…

Health Care Factors Influencing Teen Mothers' Use Of ...

African Journals Online (AJOL)

Objective: The study seeks to examine factors associated with teen mothers' use of modern contraceptives after giving birth. Methods: The 2010 Malawi Demographic and Health Survey data was used to test the study objective. A sample of 12, 911 teen mothers aged between 10 and 18 years were extracted from 23, 020 ...

Neuromuscular function during drop jumps in young and elderly males.

Science.gov (United States)

Piirainen, Jarmo M; Linnamo, Vesa; Sippola, Niina; Avela, Janne

2012-12-01

The Hoffman reflex (H-reflex), indicating alpha-motoneuron pool activity, has been shown to be task - and in resting conditions - age dependent. How aging affects H-reflex activity during explosive movements is not clear at present. The purpose of this study was to examine the effects of aging on H-reflexes during drop jumps, and its possible role in drop jump performance. Ten young (26.8 ± 2.7 years) and twenty elderly (64.2 ± 2.7 years) subjects participated in the study. Maximal drop jump performance and soleus H-reflex response (H/M jump) 20 ms after ground contact were measured in a sledge ergometer. Maximal H-reflex, maximal M-wave, Hmax/Mmax-ratio and H-reflex excitability curves were measured during standing rest. Although in young the H-reflex response (Hmax/Mmax) was 6.5% higher during relaxed standing and 19.7% higher during drop jumps (H jump/M jump) than in the elderly group, these differences were not statistically significant. In drop jumps, the elderly subjects had lower jumping height (30.4%, p push-off force (18.0%, p push-off time (31.0% p push-off force (r = 0.833, p push-off time (r = -0.857, p < 0.01) in young but not in the elderly. Correlations between H-reflex response and jumping parameters in young may indicate different jumping and activation strategies in drop jumps. However, it does not fully explain age related differences in jumping performance, since age related differences in H-reflex activity were non-significant. Copyright © 2012 Elsevier Ltd. All rights reserved.

Microscopic models of quantum-jump superoperators

International Nuclear Information System (INIS)

Dodonov, A.V.; Mizrahi, S.S.; Dodonov, V.V.

2005-01-01

We discuss the quantum-jump operation in an open system and show that jump superoperators related to a system under measurement can be derived from the interaction of that system with a quantum measurement apparatus. We give two examples for the interaction of a monochromatic electromagnetic field in a cavity (the system) with two-level atoms and with a harmonic oscillator (representing two different kinds of detectors). We show that the derived quantum-jump superoperators have a 'nonlinear' form Jρ=γ diag[F(n)aρa † F(n)], where the concrete form of the function F(n) depends on assumptions made about the interaction between the system and detector. Under certain conditions the asymptotical power-law dependence F(n)=(n+1) -β is obtained. A continuous transition to the standard Srinivas-Davies form of the quantum-jump superoperator (corresponding to β=0) is shown

Option Panels in Pure-Jump Settings

DEFF Research Database (Denmark)

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

We develop parametric inference procedures for large panels of noisy option data in the setting where the underlying process is of pure-jump type, i.e., evolve only through a sequence of jumps. The panel consists of options written on the underlying asset with a (different) set of strikes...... specification for the risk-neutral asset return dynamics, the option prices are nonlinear functions of a time-invariant parameter vector and a time-varying latent state vector (or factors). Furthermore, no-arbitrage restrictions impose a direct link between some of the quantities that may be identified from...... the return and option data. These include the so-called jump activity index as well as the time-varying jump intensity. We propose penalized least squares estimation in which we minimize L_2 distance between observed and model-implied options and further penalize for the deviation of model-implied quantities...

Teen smoking cessation help via the Internet: a survey of search engines.

Science.gov (United States)

Edwards, Christine C; Elliott, Sean P; Conway, Terry L; Woodruff, Susan I

2003-07-01

The objective of this study was to assess Web sites related to teen smoking cessation on the Internet. Seven Internet search engines were searched using the keywords teen quit smoking. The top 20 hits from each search engine were reviewed and categorized. The keywords teen quit smoking produced between 35 and 400,000 hits depending on the search engine. Of 140 potential hits, 62% were active, unique sites; 85% were listed by only one search engine; and 40% focused on cessation. Findings suggest that legitimate on-line smoking cessation help for teens is constrained by search engine choice and the amount of time teens spend looking through potential sites. Resource listings should be updated regularly. Smoking cessation Web sites need to be picked up on multiple search engine searches. Further evaluation of smoking cessation Web sites need to be conducted to identify the most effective help for teens.

Scaling the viscous circular hydraulic jump

Science.gov (United States)

Argentina, Mederic; Cerda, Enrique; Duchesne, Alexis; Limat, Laurent

2017-11-01

The formation mechanism of hydraulic jumps has been proposed by Belanger in 1828 and rationalised by Lord Rayleigh in 1914. As the Froude number becomes higher than one, the flow super criticality induces an instability which yields the emergence of a steep structure at the fluid surface. Strongly deformed liquid-air interface can be observed as a jet of viscous fluid impinges a flat boundary at high enough velocity. In this experimental setup, the location of the jump depends on the viscosity of the liquid, as shown by T. Bohr et al. in 1997. In 2014, A. Duchesne et al. have established the constancy of the Froude number at jump. Hence, it remains a contradiction, in which the radial hydraulic jump location might be explained through inviscid theory, but is also viscosity dependent. We present a model based on the 2011 Rojas et al. PRL, which solves this paradox. The agreement with experimental measurements is excellent not only for the prediction of the position of the hydraulic jump, but also for the determination of the fluid thickness profile. We predict theoretically the critical value of the Froude number, which matches perfectly to that measured by Duchesne et al. We acknowledge the support of the CNRS and the Universit Cte d'Azur, through the IDEX funding.

Marfan Syndrome (For Teens)

Science.gov (United States)

... genetic disorder called Marfan syndrome. What Is Marfan Syndrome? Marfan syndrome is named after Antoine Marfan, the French ... immediately. What's Life Like for Teens With Marfan Syndrome? Marfan syndrome affects people differently, so life is not ...

Bipolar Disorder (For Teens)

Science.gov (United States)

... hospital or residential treatment center, in the juvenile justice system, abusing drugs, or committing suicide. Because children ... site. Note: All information on TeensHealth® is for educational purposes only. For specific medical advice, diagnoses, and ...

Jump phenomena. [large amplitude responses of nonlinear systems

Science.gov (United States)

Reiss, E. L.

1980-01-01

The paper considers jump phenomena composed of large amplitude responses of nonlinear systems caused by small amplitude disturbances. Physical problems where large jumps in the solution amplitude are important features of the response are described, including snap buckling of elastic shells, chemical reactions leading to combustion and explosion, and long-term climatic changes of the earth's atmosphere. A new method of rational functions was then developed which consists of representing the solutions of the jump problems as rational functions of the small disturbance parameter; this method can solve jump problems explicitly.

Jump Testing and the Speed of Market Adjustment

DEFF Research Database (Denmark)

Rasmussen, Torben B.

Asymptotic properties of jump tests rely on the property that any jump occurs within a single time interval no matter what the observation frequency is. Market microstructure effects in relation to news-induced revaluation of the underlying variable is likely to make this an unrealistic assumption...... for high-frequency transaction data. To capture these microstructure effects, this paper suggests a model in which market prices adjust gradually to jumps in the underlying effcient price. A case study illustrates the empirical relevance of the model, and the performance of different jump tests...

Jumping together

DEFF Research Database (Denmark)

Lund, Ole; Ravn, Susanne; Christensen, Mette Krogh

2014-01-01

, in order to reach a deeper understanding of how practice facilitates learning. Results: We encircle the athletes’ interrelated learning processes by introducing the training environment of the national team and situations in which the athletes guide each other verbally or by jumping together. Discussion...

Teen Birth Rate. Facts at a Glance, 2002.

Science.gov (United States)

Papillo, Angela Romano, Comp.; Franzetta, Kerry, Comp.; Manlove, Jennifer, Comp.; Moore, Kristin Anderson, Comp.; Terry-Humen, Elizabeth, Comp.; Ryan, Suzanne, Comp.

This publication reports trends in teen childbearing in the nation, in each state, and in large cities using data from the 2001 National Center for Health Statistics (NCHS). Rates of teenage childbearing continue to steadily decline, and the 2001 rates are historic lows for each age group. NCHS data showed that almost 80% of teen births nationwide…

Urban Teens in the Library: Research and Practice

Science.gov (United States)

Agosto, Denise E., Ed.; Hughes-Hassell, Sandra, Ed.

2009-01-01

"Urban Teens in the Library" is the perfect solution for the concerns and uncertainty many librarians face when supporting this group of patrons and students. From a team of experts who have researched the information habits and preferences of urban teens to build better and more effective school and public library programs, this book will show…

Do Mothers' Opinions Matter in Teens' Sexual Activity?

Science.gov (United States)

Fingerson, Laura

2005-01-01

Using the Add Health data (N = 9,530 dyads), this study explores sexual socialization in the family using the theory of reasoned action by assessing how mothers' opinions are associated with their childrens' sexual behavior. Findings suggest that the more sexually liberal teens think their mothers are, the more likely the teens are to have higher…

Effect of drop jump technique on the reactive strength index.

Science.gov (United States)

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

2016-09-01

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

Meniscus Tears (For Teens)

Science.gov (United States)

... Safe Videos for Educators Search English Español Meniscus Tears KidsHealth / For Teens / Meniscus Tears What's in this ... surgery to fix it. What Is a Meniscus Tear? Your knee is made up of three bones: ...

Delayed Puberty (For Teens)

Science.gov (United States)

... Safe Videos for Educators Search English Español Delayed Puberty KidsHealth / For Teens / Delayed Puberty What's in this ... wonder if there's anything wrong. What Is Delayed Puberty? Puberty is the time when your body grows ...

Dynamics and stability of directional jumps in the desert locust.

Science.gov (United States)

Gvirsman, Omer; Kosa, Gabor; Ayali, Amir

2016-01-01

Locusts are known for their ability to jump large distances to avoid predation. The jump also serves to launch the adult locust into the air in order to initiate flight. Various aspects of this important behavior have been studied extensively, from muscle physiology and biomechanics, to the energy storage systems involved in powering the jump, and more. Less well understood are the mechanisms participating in control of the jump trajectory. Here we utilise video monitoring and careful analysis of experimental directional jumps by adult desert locusts, together with dynamic computer simulation, in order to understand how the locusts control the direction and elevation of the jump, the residual angular velocities resulting from the jump and the timing of flapping-flight initiation. Our study confirms and expands early findings regarding the instrumental role of the initial body position and orientation. Both real-jump video analysis and simulations based on our expanded dynamical model demonstrate that the initial body coordinates of position (relative to the hind-legs ground-contact points) are dominant in predicting the jumps' azimuth and elevation angles. We also report a strong linear correlation between the jumps' pitch-angular-velocity and flight initiation timing, such that head downwards rotations lead to earlier wing opening. In addition to offering important insights into the bio-mechanical principles of locust jumping and flight initiation, the findings from this study will be used in designing future prototypes of a bio-inspired miniature jumping robot that will be employed in animal behaviour studies and environmental monitoring applications.

76 FR 6307 - National Teen Dating Violence Awareness and Prevention Month, 2011

Science.gov (United States)

2011-02-03

... one in four teens report being the victim of verbal, physical, emotional, or sexual violence. Abusive... National Teen Dating Violence Awareness and Prevention Month, 2011 By the President of the United States of America A Proclamation National Teen Dating Violence Awareness and Prevention Month reflects our Nation's...

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

Science.gov (United States)

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

2012-06-01

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

Not Just Another Single Issue: Teen Pregnancy Prevention's Link to Other Critical Social Issues.

Science.gov (United States)

National Campaign To Prevent Teen Pregnancy, Washington, DC.

This report discusses critical social issues linked to teen pregnancy, explaining that teen pregnancy prevention should be viewed as working to improve these social issues. After providing general background on teen pregnancy, the report offers five fact sheets: (1) "Teen Pregnancy, Welfare Dependency, and Poverty" (continuing to reduce…

Teen Pregnancy - What You Need to Know PSA (:60)

Centers for Disease Control (CDC) Podcasts

This 60 second PSA is based on the April, 2011 CDC Vital Signs report. Having a child during the teen years comes at a high cost to the young mother, her child, and the community. Get tips to help break the cycle of teen pregnancy.

Endocrine System (For Teens)

Science.gov (United States)

... That Can Go Wrong Print en español El sistema endocrino Ever dozed through chemistry class and wondered ... of Use Notice of Nondiscrimination Visit the Nemours Web site. Note: All information on TeensHealth® is for ...

Coalescence-induced jumping of micro-droplets on heterogeneous superhydrophobic surfaces

Science.gov (United States)

Attarzadeh, Reza; Dolatabadi, Ali

2017-01-01

The phenomenon of droplets coalescence-induced self-propelled jumping on homogeneous and heterogeneous superhydrophobic surfaces was numerically modeled using the volume of fluid method coupled with a dynamic contact angle model. The heterogeneity of the surface was directly modeled as a series of micro-patterned pillars. To resolve the influence of air around a droplet and between the pillars, extensive simulations were performed for different droplet sizes on a textured surface. Parallel computations with the OpenMP algorithm were used to accelerate computation speed to meet the convergence criteria. The composition of the air-solid surface underneath the droplet facilitated capturing the transition from a no-slip/no-penetration to a partial-slip with penetration as the contact line at triple point started moving to the air pockets. The wettability effect from the nanoscopic roughness and the coating was included in the model by using the intrinsic contact angle obtained from a previously published study. As the coalescence started, the radial velocity of the coalescing liquid bridge was partially reverted to the upward direction due to the counter-action of the surface. However, we found that the velocity varied with the size of the droplets. A part of the droplet kinetic energy was dissipated as the merged droplet started penetrating into the cavities. This was due to a different area in contact between the liquid and solid and, consequently, a higher viscous dissipation rate in the system. We showed that the effect of surface roughness is strongly significant when the size of the micro-droplet is comparable with the size of the roughness features. In addition, the relevance of droplet size to surface roughness (critical relative roughness) was numerically quantified. We also found that regardless of the viscous cutoff radius, as the relative roughness approached the value of 44, the direct inclusion of surface topography was crucial in the modeling of the

Teen worker safety training: methods used, lessons taught, and time spent.

Science.gov (United States)

Zierold, Kristina M

2015-05-01

Safety training is strongly endorsed as one way to prevent teens from performing dangerous tasks at work. The objective of this mixed methods study was to characterize the safety training that teenagers receive on the job. From 2010 through 2012, focus groups and a cross-sectional survey were conducted with working teens. The top methods of safety training reported were safety videos (42 percent) and safety lectures (25 percent). The top lessons reported by teens were "how to do my job" and "ways to spot hazards." Males, who were more likely to do dangerous tasks, received less safety training than females. Although most teens are getting safety training, it is inadequate. Lessons addressing safety behaviors are missing, training methods used are minimal, and the time spent is insignificant. More research is needed to understand what training methods and lessons should be used, and the appropriate safety training length for effectively preventing injury in working teens. In addition, more research evaluating the impact of high-quality safety training compared to poor safety training is needed to determine the best training programs for teens. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Mobile Phones Bridging the Digital Divide for Teens in the US?

DEFF Research Database (Denmark)

Brown, Katie; Campbell, Scott; Ling, Richard

2011-01-01

In 2009, just 27% of American teens with mobile phones reported using their devices to access the internet. However, teens from lower income families and minority teens were significantly more likely to use their phones to go online. Together, these surprising trends suggest a potential narrowing...... of the digital divide, offering internet access to those without other means of going online. This is an important move, as, in today’s society, internet access is central to active citizenship in general and teen citizenship in particular. Yet the cost of this move toward equal access is absorbed by those who...... as non-use) of the internet through mobile phones....

Cerebral Palsy (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Cerebral Palsy KidsHealth / For Teens / Cerebral Palsy What's in this ... do just what everyone else does. What Is Cerebral Palsy? Cerebral palsy (CP) is a disorder of the ...

Lactose Intolerance (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Lactose Intolerance KidsHealth / For Teens / Lactose Intolerance What's in this ... t really consider it a disease. Who Gets Lactose Intolerance? A person may be or may become lactose ...

Blood Transfusions (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Blood Transfusions KidsHealth / For Teens / Blood Transfusions What's in this ... in his or her body. What Is a Blood Transfusion? A transfusion is a simple medical procedure that ...

Understanding Teen Dating Violence

Science.gov (United States)

Understanding Teen Dating Violence Fact Sheet 2014 Dating violence is a type of intimate partner violence. It occurs between two people in a close relationship. The nature of dating violence can be physical, emotional, or sexual. • Physical— This ...

Impact of wave phase jumps on stochastic heating

International Nuclear Information System (INIS)

Zasenko, V.I.; Zagorodny, A.G.; Cherniak, O.M.

2016-01-01

Interaction of charged particles with fields of random waves brings about known effects of stochastic acceleration and heating. Jumps of wave phases can increase the intensity of these processes substantially. Numerical simulation of particle heating and acceleration by waves with regular phases, waves with jumping phase and stochastic electric field impulses is performed. Comparison of the results shows that to some extent an impact of phase jumps is similar to the action of separate field impulses. Jumps of phase not only increase the intensity of resonant particle heating but involves in this process non-resonant particles from a wide range of initial velocities

Localization of the endpoints of deletions in the 5' region of the Duchenne gene using a sequence isolated by chromosome jumping

Energy Technology Data Exchange (ETDEWEB)

Kenwrick, S J; Smith, T J; England, S; Collins, F; Davies, K E

1988-02-25

The authors have used chromosome jumping technology to move from within a large intron sequence in the Duchenne muscular dystrophy (DMD) gene to a region adjacent to exons of the gene. The single copy jump clone, HH1, was used to characterize deletions in patients previously shown to be deleted for DNA markers in the 5' end of the gene. 12 out of 15 such patients have breakpoints which lie between HH1 and the genomic locus J-47. Thus the vast majority of the deletions in these patients have proximal breakpoints in a similar region distal to the 5'end of the gene. HH1 was mapped with respect to the X;1 translocation in a DMD female and was shown to lie at least 80 kb from the starting point of the chromosome jump, HIP25.

Option Valuation with Observable Volatility and Jump Dynamics

DEFF Research Database (Denmark)

Christoffersen, Peter; Feunou, Bruno; Jeon, Yoontae

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

Mesopause Jumps: Observations and Explanation

Science.gov (United States)

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

2017-12-01

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

The effect of spending cuts on teen pregnancy.

Science.gov (United States)

Paton, David; Wright, Liam

2017-07-01

In recent years, English local authorities have been forced to make significant cuts to devolved expenditure. In this paper, we examine the impact of reductions in local expenditure on one particular public health target: reducing rates of teen pregnancy. Contrary to predictions made at the time of the cuts, panel data estimates provide no evidence that areas which reduced expenditure the most have experienced relative increases in teenage pregnancy rates. Rather, expenditure cuts are associated with small reductions in teen pregnancy rates, a result which is robust to a number of alternative specifications and tests for causality. Underlying socio-economic factors such as education outcomes and alcohol consumption are found to be significant predictors of teen pregnancy. Copyright © 2017 Elsevier B.V. All rights reserved.

Teen Sexual Health

Science.gov (United States)

During your teens you go through puberty and become sexually mature. If you're a girl, you develop breasts and begin to get your period. If you're a boy, your penis and testicles become larger. If you have sex, you could get pregnant or get someone pregnant. Whether you choose to have sex ...

Teens, Health and Technology: A National Survey

OpenAIRE

Ellen Wartella; Vicky Rideout; Heather Montague; Leanne Beaudoin-Ryan; Alexis Lauricella

2016-01-01

In the age of digital technology, as teens seem to be constantly connected online, via social media, and through mobile applications, it is no surprise that they increasingly turn to digital media to answer their health questions. This study is the first of its kind to survey a large, nationally-representative sample of teens to investigate how they use the newest digital technologies, including mobile apps, social networking sites, electronic gaming and wearable devices, to explore health...

Teen Depression and Suicide, A SILENT CRISIS.

Science.gov (United States)

Kroning, Maureen; Kroning, Kayla

2016-01-01

Adolescent depression is a serious problem affecting 10.7% of all teens and 29.9% of high school students; 17% of high school students have contemplated suicide. Yet, depression in teens is often unrecognized. This article relays the tragic death of a 17-year-old, along with symptoms of depression and suicide in adolescents; DSM-5 criteria for depression; treatments including protective factors, psychotherapy, and medications; and imparts interventions for addressing this huge but silent crisis.

Quantum jumps on Anderson attractors

Science.gov (United States)

Yusipov, I. I.; Laptyeva, T. V.; Ivanchenko, M. V.

2018-01-01

In a closed single-particle quantum system, spatial disorder induces Anderson localization of eigenstates and halts wave propagation. The phenomenon is vulnerable to interaction with environment and decoherence that is believed to restore normal diffusion. We demonstrate that for a class of experimentally feasible non-Hermitian dissipators, which admit signatures of localization in asymptotic states, quantum particle opts between diffusive and ballistic regimes, depending on the phase parameter of dissipators, with sticking about localization centers. In a diffusive regime, statistics of quantum jumps is non-Poissonian and has a power-law interval, a footprint of intermittent locking in Anderson modes. Ballistic propagation reflects dispersion of an ordered lattice and introduces the second timescale for jumps, resulting in non-nonmonotonous probability distribution. Hermitian dephasing dissipation makes localization features vanish, and Poissonian jump statistics along with normal diffusion are recovered.

Anabolic Steroids (For Teens)

Science.gov (United States)

... the percentage of teens who misuse steroids. Swipe left or right to scroll. Monitoring the Future Study: Trends in ... Drugs of Abuse Discover what happens to the brain on drugs. ... vs. drug use. Read More » 92 Comments Dopers Downfall ...

Exposure to and Views of Information about Sexual Abstinence among Older Teens

Science.gov (United States)

Jones, Rachel K.; Biddlecom, Ann E.

2011-01-01

There is scant research of adolescents' understanding of abstinence. We conducted interviews with a sample of 58 teens to find out their exposure to abstinence information from a range of sources. Most teens had received abstinence information or messages from school, family members, and friends. For many teens, information about abstinence, or…

Propulsion efficiency and imposed flow fields of a copepod jump

DEFF Research Database (Denmark)

Jiang, H.; Kiørboe, Thomas

2011-01-01

Pelagic copepods jump to relocate, to attack prey and to escape predators. However, there is a price to be paid for these jumps in terms of their energy costs and the hydrodynamic signals they generate to rheotactic predators. Using observed kinematics of various types of jumps, we computed...... the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump...... the flow structure. The flow field associated with an escape jump sequence also includes two dominant vortex structures: one leading wake vortex generated as a result of the first jump and one around the body, but between these two vortex structures is an elongated, long-lasting flow trail with flow...

Kauffman Teen Survey. An Annual Report on Teen Health Behaviors: Use of Alcohol, Tobacco, and Other Drugs among 8th-, 10th-, and 12th-Grade Students in Greater Kansas City, 1991-92 to 2000-01.

Science.gov (United States)

Ewing Marion Kauffman Foundation, Kansas City, MO.

The Ewing Marion Kauffman Foundation began surveying Kansas City area teens during the 1984-85 school year. The Kauffman Teen Survey now addresses two sets of issues for teens. Teen Health Behaviors, addressed in this report, have been a focus of the survey since its inception. The report focuses on teen use of alcohol, tobacco, and other drugs in…

About Teen Suicide (For Parents)

Science.gov (United States)

... thoughts. Teens going through major life changes (parents' divorce, moving, a parent leaving home due to military service or parental separation, financial changes) and those who are victims of ...

Exploring African-American and Latino Teens' Perceptions of Contraception and Access to Reproductive Health Care Services

OpenAIRE

Galloway, Charlotte T.; Duffy, Jennifer L.; Dixon, Rena P.; Fuller, Taleria R.

2017-01-01

Purpose Reducing disparities in teen pregnancy and birth rates among African American and Latina teens is a central focus of a community-wide teen pregnancy prevention initiative implemented by the South Carolina Campaign to Prevent Teen Pregnancy. Disparities in teen pregnancy and birth rates are driven, in part, by differential access to contraception and reproductive health care services. The purpose of this qualitative study was to understand African American and Latino teens? 1) preferen...

Teen Births: Examining the Recent Increase. Research Brief. Publication #2009-08

Science.gov (United States)

Moore, Kristin Anderson

2009-01-01

After a 14-year decline, the teen birth rate increased in 2006, according to data from the National Center for Health Statistics. Between 2005 and 2006, the teen birth rate rose 3.5 percent, from 40.5 to 41.9 births per 1,000 females aged 15-19. The number of teen births rose by 20,843, from 414,593 to 435,436 births, the largest annual increase…

The Prevessin Control Room during LEP's start up in 1989.

CERN Multimedia

1989-01-01

The Prévessin Control Room saw its first momentous event when the 400 GeV beam for the SPS was commissioned in the presence of Project Leader John Adams. It was also here that the first proton-antiproton collisions were observed, in 1981. Eight years later, in 1989, operators and directors alike jumped for joy at the announcement of the first electron-positron collisions at the start up of LEP, the biggest accelerator in the world.

The hydraulic jump and ripples in liquid helium

International Nuclear Information System (INIS)

Rolley, E.; Guthmann, C.; Pettersen, M.S.

2007-01-01

We have studied the characteristics of the circular hydraulic jump using liquid helium. Surprisingly, the radius of the jump does not change at the superfluid transition. We think that the flow is still dissipative below the lambda point because the velocity exceeds the critical one. The jump radius R j is compared with various models. In our parameter range, we find that the jump can be treated as a shock, and that capillary effects are important. Below the superfluid transition, we observed a standing capillary wave between the impact of the jet and the jump. Assuming that the superfluid flow can be described with an effective viscosity, we calculate the wave vector and thus obtain the value of the liquid thickness, which is in reasonable agreement with predictions. However, the spatial variation of the wave amplitude depends much more strongly on temperature than we calculate

Numerical simulations of katabatic jumps in coats land, Antartica

Science.gov (United States)

Yu, Ye; Cai, Xiaoming; King, John C.; Renfrew, Ian A.

A non-hydrostatic numerical model, the Regional Atmospheric Modeling System (RAMS), has been used to investigate the development of katabatic jumps in Coats Land, Antarctica. In the control run with a 5 m s-1downslope directed initial wind, a katabatic jump develops near the foot of the idealized slope. The jump is manifested as a rapid deceleration of the downslope flow and a change from supercritical to subcritical flow, in a hydraulic sense, i.e., the Froude number (Fr) of the flow changes from Fr > 1 to Fr> 1. Results from sensitivity experiments show that an increase in the upstream flow rate strengthens the jump, while an increase in the downstream inversion-layer depth results in a retreat of the jump. Hydraulic theory and Bernoulli''s theorem have been used to explain the surface pressure change across the jump. It is found that hydraulic theory always underestimates the surface pressure change, while Bernoulli''s theorem provides a satisfactory estimation. An analysis of the downs balance for the katabatic jump indicates that the important forces are those related to the pressure gradient, advection and, to a lesser extent, the turbulent momentum divergence. The development of katabatic jumps can be divided into two phases. In phase I, the t gradient force is nearly balanced by advection, while in phase II, the pressure gradient force is counterbalanced by turbulent momentum divergence. The upslope pressure gradient force associated with a pool of cold air over the ice shelf facilitates the formation of the katabatic jump.

Computer Forensics JumpStart

CERN Document Server

Solomon, Michael G; Tittel, Ed; Broom, Neil; Barrett, Diane

2011-01-01

Essential reading for launching a career in computer forensicsInternet crime is on the rise, catapulting the need for computer forensics specialists. This new edition presents you with a completely updated overview of the basic skills that are required as a computer forensics professional. The author team of technology security veterans introduces the latest software and tools that exist and they review the available certifications in this growing segment of IT that can help take your career to a new level. A variety of real-world practices take you behind the scenes to look at the root causes

Development of a Minimally Actuated Jumping-Rolling Robot

Directory of Open Access Journals (Sweden)

Thanhtam Ho

2015-04-01

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

Turner Syndrome (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Turner Syndrome KidsHealth / For Teens / Turner Syndrome What's in this ... en español El síndrome de Turner What Is Turner Syndrome? Turner syndrome (TS) is a genetic condition found ...

Bell's Palsy (For Teens)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Bell's Palsy KidsHealth / For Teens / Bell's Palsy What's in this ... Print en español Parálisis de Bell What Is Bell's Palsy? Bell's palsy is a temporary weakness or paralysis ...

Just say "I don't": lack of concordance between teen report and biological measures of drug use.

Science.gov (United States)

Delaney-Black, Virginia; Chiodo, Lisa M; Hannigan, John H; Greenwald, Mark K; Janisse, James; Patterson, Grace; Huestis, Marilyn A; Ager, Joel; Sokol, Robert J

2010-11-01

Prevalence estimates of illicit drug use by teens are typically generated from confidential or anonymous self-report. While data comparing teen self-report with biological measures are limited, adult studies identify varying degrees of under-reporting. Hair analyses for cocaine, opiates and marijuana were compared to confidential teen self- and parent-reported teen drug use in a longitudinal cohort of >400 high-risk urban teens and parents. Both teens and parents substantially underreported recent teen cocaine and opiate use. However, compared with parents, teens were more likely to deny biomarker-verified cocaine use. Teen specimens (hair) were 52 times more likely to identify cocaine use compared with self-report. Parent hair analyses for cocaine and opiate use were 6.5 times and 5.5 times, respectively, more likely to indicate drug use than were parental self-report. The lack of concordance between self-report and bioassay occurred despite participant's knowledge that a "certificate of confidentiality" protected both teen and adult participants, and that the biological specimens would be tested for drugs. These findings confirm prior reports of adult under-reporting of their own drug use while extending our understanding of teen's self-admitted drug use. The lack of concordance between teen self- or parent-reported teen drug use and biomarkers confirm our concerns that both teen- and parent-reported teen drug use is limited, at least for youth in high-risk urban settings. Methods of ascertainment other than self- or parent-report must be considered when health care providers, researchers and public health agencies attempt to estimate teen drug-use prevalence.

Jumping to (fatal) conclusions? An analysis of video film on a social networking web site of recreational jumping from height into water.

Science.gov (United States)

Moran, Kevin

2014-01-01

In high-income countries, death as a consequence of recreational jumping into water from height has not been well investigated partly because it traditionally has been a covert activity within youth culture. An observational study of video recordings posted on the YouTube web site was used to gather data on the nature of jumping activity in New Zealand and Australia. An analytical framework was developed to identify site- participant- social characteristics (10 variables) and online feedback (4 variables). Of the 389 videos recorded in New Zealand (n = 210) and Australia (n = 179), 929 jumpers were observed, and rivers were the most frequently reported site of jumping activity (New Zealand 47%; Australia 35%). One fifth (20%) of the jumps in New Zealand and one third (33%) in Australia were from heights estimated to be more than 12 m. The YouTube website portraying jumps from height were visited almost half a million times (495,686 hits). Ways of reducing recreational jumping risk via targeted education interventions may be best directed at young male adults. Use of social network sites to foster safe behaviours may be an effective way to educate young people of the inherent risks of jumping from height into water.

A simple strategy for jumping straight up.

Science.gov (United States)

Hemami, Hooshang; Wyman, Bostwick F

2012-05-01

Jumping from a stationary standing position into the air is a transition from a constrained motion in contact with the ground to an unconstrained system not in contact with the ground. A simple case of the jump, as it applies to humans, robots and humanoids, is studied in this paper. The dynamics of the constrained rigid body are expanded to define a larger system that accommodates the jump. The formulation is applied to a four-link, three-dimensional system in order to articulate the ballistic motion involved. The activity of the muscular system and the role of the major sagittal muscle groups are demonstrated. The control strategy, involving state feedback and central feed forward signals, is formulated and computer simulations are presented to assess the feasibility of the formulations, the strategy and the jump. Copyright © 2012 Elsevier Inc. All rights reserved.

Sub-Poissonian statistics of quantum jumps in single molecule or atomic ion

International Nuclear Information System (INIS)

Osad'ko, I.S.; Gus'kov, D.N.

2007-01-01

A theory for statistics of quantum jumps in single molecule or ion driven by continues wave laser field is developed. These quantum jumps can relate to nonradiative singlet-triplet transitions in a molecule or to on → off jumps in a single ion with shelving processes. Distribution function w N (T) of quantum jumps in time interval T is found. Computer simulation of quantum jumps is realized. Statistical treatment of simulated jumps reveals sub-Poissonian statistics of quantum jumps. The theoretical distribution function w N (T) fits well the distribution of jumps found from simulated data. Experimental data on quantum jumps found in experiments with single Hg + ion are described by the function w N (T) well

La Marihuana: Informacion para los Adolescentes. Revisada (Marijuana: Facts for Teens. Revised).

Science.gov (United States)

National Inst. on Drug Abuse (DHHS/PHS), Rockville, MD.

Using a question and answer format, this booklet is designed to inform teens about the dangers of marijuana usage. Inset facts about marijuana and teen perspectives compliment the following topics: (1) What is marijuana? (2) How is marijuana used? (3) How long does marijuana stay in the user's body? (4) How many teens smoke marijuana? (5) Why do…

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

Science.gov (United States)

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

2007-09-01

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

Gaming Against Violence: A Grassroots Approach to Teen Dating Violence.

Science.gov (United States)

Crecente, Drew

2014-08-01

Teen dating violence is a pervasive problem that affects millions of adolescents worldwide. Although there have been various approaches to addressing this problem, using videogames had not been employed before 2008, when Jennifer Ann's Group, an Atlanta, GA-based nonprofit organization, created an annual competition. The Life.Love. Game Design Challenge rewards game developers for creating videogames about teen dating violence without using any violence in the games themselves. The resulting videogames have increased awareness about teen dating violence and provided educational information to assist adolescents, parents, and teachers in identifying abusive relationships.

Optimal Ski Jump

Science.gov (United States)

Rebilas, Krzysztof

2013-02-01

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

An Injury Prevention Strategy for Teen Restaurant Workers

Science.gov (United States)

Ward, Julie A.; de Castro, A. B.; Tsai, Jenny Hsin-Chun; Linker, Darren; Hildahl, Lyle; Miller, Mary E.

2011-01-01

High levels of youth employment, workplace hazards, and characteristics unique to adolescents contribute to a relatively high incidence of injuries among teens in the restaurant industry. This article discusses the ProSafety model of injury prevention among teen restaurant workers. Through integration with an existing career and technical education program, the ProSafety project seeks to prevent occupational injuries among the teen worker population through classroom safety education and internship skills reinforcement. ProSafety is the product of an innovative collaboration with occupational health nurses, business professionals, educators, and government. Its approach is derived from Social Cognitive Theory, is consistent with key values and strategies of occupational health nurses, and provides lessons for practitioners seeking to reduce occupational injuries in food service or among other populations of adolescent workers. PMID:20180503

Body Image (Children and Teens)

Science.gov (United States)

... Kids and Teens Pregnancy and Childbirth Women Men Seniors Your Health Resources Healthcare Management End-of-Life Issues Insurance & Bills Self Care Working With Your Doctor Drugs, Procedures & Devices Over-the- ...

Teen magazines as educational texts on dating violence: the $2.99 approach.

Science.gov (United States)

Kettrey, Heather Hensman; Emery, Beth C

2010-11-01

This study analyzed the portrayal of dating violence in teen magazines published in the United States. Such an investigation is important because previous research indicates that dating violence is a serious problem facing adolescents, teen magazines overemphasize the importance of romantic relationships, and teens who read this genre frequently or for education/advice are especially susceptible to its messages. Results indicated that although teen magazines do frame dating violence as a cultural problem, they are much more likely to utilize an individual frame that emphasizes the victim. Results were discussed as they apply to the responsibilities of professionals working with adolescents.

Vital Signs – Preventing Repeat Teen Births

Centers for Disease Control (CDC) Podcasts

2013-04-02

This podcast is based on the April 2013 CDC Vital Signs report, which discusses repeat teen births and ways teens, parents and guardians, health care providers, and communities can help prevent them.  Created: 4/2/2013 by Centers for Disease Control and Prevention (CDC).   Date Released: 4/2/2013.

Localization of the endpoints of deletions in the 5' region of the Duchenne gene using a sequence isolated by chromosome jumping

Energy Technology Data Exchange (ETDEWEB)

Kenwrick, S.J.; Smith, T.J.; England, S.; Collins, F.; Davies, K.E.

1988-02-25

The authors have used chromosome jumping technology to move from within a large intron sequence in the Duchenne muscular dystrophy (DMD) gene to a region adjacent to exons of the gene. The single copy jump clone, HH1, was used to characterize deletions in patients previously shown to be deleted for DNA markers in the 5' end of the gene. 12 out of 15 such patients have breakpoints which lie between HH1 and the genomic locus J-47. Thus the vast majority of the deletions in these patients have proximal breakpoints in a similar region distal to the 5'end of the gene. HH1 was mapped with respect to the X;1 translocation in a DMD female and was shown to lie at least 80 kb from the starting point of the chromosome jump, HIP25.

Anthropic prediction for a large multi-jump landscape

International Nuclear Information System (INIS)

Schwartz-Perlov, Delia

2008-01-01

The assumption of a flat prior distribution plays a critical role in the anthropic prediction of the cosmological constant. In a previous paper we analytically calculated the distribution for the cosmological constant, including the prior and anthropic selection effects, in a large toy 'single-jump' landscape model. We showed that it is possible for the fractal prior distribution that we found to behave as an effectively flat distribution in a wide class of landscapes, but only if the single-jump size is large enough. We extend this work here by investigating a large (N∼10 500 ) toy 'multi-jump' landscape model. The jump sizes range over three orders of magnitude and an overall free parameter c determines the absolute size of the jumps. We will show that for 'large' c the distribution of probabilities of vacua in the anthropic range is effectively flat, and thus the successful anthropic prediction is validated. However, we argue that for small c, the distribution may not be smooth

The research of tactics of the competitive activity of the qualified sportswomen in long jumps

OpenAIRE

Grebenyuk, Oleg

2016-01-01

Grebenyuk A. Purpose: to research features of competitive tactics of the qualified sportswomen in long jumps from the running start. Material & Methods: such methods were applied the in researches: analysis of scientific and methodical literature, pedagogical supervision, content analysis (analysis of protocols of competitions). Results of 152 jumpers in length, who executed 886 attempts, are analyzed for the solution of the stated purpose. Results: options of competitive tactics of the q...

Scaling and jumping: Gravity loses grip on small jumpers

NARCIS (Netherlands)

Scholz, M.N.; Bobbert, M.F.; van Soest, A.J.

2006-01-01

There are several ways to quantify jumping performance, a common definition being the height gained by the body's centre of mass (CM) in the airborne phase. Under this definition, jump height is determined by take-off velocity. According to the existing literature on jumping and scaling, take-off

Jumping hoops on water

Science.gov (United States)

Yang, Eunjin; Kim, Ho-Young

2015-11-01

Small aquatic arthropods, such as water striders and fishing spiders, are able to jump off water to a height several times their body length. Inspired by the unique biological motility on water, we study a simple model using a flexible hoop to provide fundamental understanding and a mimicking principle of small jumpers on water. Behavior of a hoop on water, which is coated with superhydrophobic particles and initially bent into an ellipse from an equilibrium circular shape, is visualized with a high speed camera upon launching it into air by releasing its initial elastic strain energy. We observe that jumping of our hoops is dominated by the dynamic pressure of water rather than surface tension, and thus it corresponds to the dynamic condition experienced by fishing spiders. We calculate the reaction forces provided by water adopting the unsteady Bernoulli equation as well as the momentum loss into liquid inertia and viscous friction. Our analysis allows us to predict the jumping efficiency of the hoop on water in comparison to that on ground, and to discuss the evolutionary pressure rendering fishing spiders select such dynamic behavior.

Is a driver's license age waiver worth a teen's life?

Science.gov (United States)

Porter, Dawn M; Miller, Beverly K; Mullins, Samantha H; Porter, Mary E; Aitken, Mary E

2018-04-10

Motor vehicle crashes are the leading cause of death for teens 14-19 years of age, with younger teen drivers at higher risk than older teens. Graduated driver licensing has been proven to reduce teen driver-related motor vehicle crashes and fatalities. Arkansas allows parents to request age waivers, which allow a teen to obtain a license for independent driving before the sixteenth birthday. The objectives of this study were to: (1) determine the prevalence of age waivers issued in Arkansas and (2) determine motor vehicle crash risks associated with 14 and 15 year old drivers. This is a brief report on an informative query exploring risk factors related to age waivers. Publicly available databases were utilized for across state comparisons. The Web-based Injury Statistics Query and Reporting Systems (WISQARS) was utilized to calculate motor vehicle crash crude death rates. National Highway Traffic Safety Administration data were utilized to identify seat belt use rates. The Fatal Analysis Reporting System (FARS) was utilized to identify crash fatality risks for 14 and 15 year old drivers in Arkansas (N = 24). Age waiver data were obtained from the Arkansas Driver Control Administration. De-identified data on fatal crashes and rates of age waiver issuance in Arkansas for 14 and 15 year olds from 2004 through 2016 were calculated. We reviewed crash data for 14 and 15 year old drivers in Arkansas between 2004 and 2014 to determine fatality risks. Thirty-one out of seventy-five counties in Arkansas were above the state age waiver issuance rate of 30.4 per 1000 14 to 15 year old teens. Among the four states that had similar age waivers for 14 to 15 year olds, Arkansas had the highest motor vehicle death rate of 10.2 per 100,000 young teens and the lowest seat belt use rate at 73%. Arkansas had the highest reported teen crash fatality rates among 4 states with age waivers. The volume of age waivers issued in Arkansas is concerning. Further research is needed

Teen Pregnancy — What You Need to Know

Centers for Disease Control (CDC) Podcasts

This podcast is based on the April, 2011 CDC Vital Signs report. Having a child during the teen years comes at a high cost to the young mother, her child, and the community. Get tips to help break the cycle of teen pregnancy.

Teen driver support system (TDSS) field operational test : final report.

Science.gov (United States)

2015-11-01

Although teen drivers make up a small percentage of the U.S. driving population, they are at an especially high risk : of being involved in a crash. Factors that contribute to teen drivers risk include their lack of experience and their : tendency...

Gender differences in residual effect of prior drop jumps on oxygen uptake during heavy cycling exercise

Directory of Open Access Journals (Sweden)

Neringa Baranauskienė

2017-12-01

Conclusions: Prior eccentric–concentric exercise of thigh muscles (100 drop jumps accelerates VO2 kinetics at the start and increases VO2 during steady state of heavy cycling only in the male group. So, prior exercise of such type has a higher negative impact on cycling economy in men than in women and this might be related to greater muscle damage and fatigue in physically active male persons after plyometric exercise.

Dynamics and stability of directional jumps in the desert locust

Directory of Open Access Journals (Sweden)

Omer Gvirsman

2016-09-01

Full Text Available Locusts are known for their ability to jump large distances to avoid predation. The jump also serves to launch the adult locust into the air in order to initiate flight. Various aspects of this important behavior have been studied extensively, from muscle physiology and biomechanics, to the energy storage systems involved in powering the jump, and more. Less well understood are the mechanisms participating in control of the jump trajectory. Here we utilise video monitoring and careful analysis of experimental directional jumps by adult desert locusts, together with dynamic computer simulation, in order to understand how the locusts control the direction and elevation of the jump, the residual angular velocities resulting from the jump and the timing of flapping-flight initiation. Our study confirms and expands early findings regarding the instrumental role of the initial body position and orientation. Both real-jump video analysis and simulations based on our expanded dynamical model demonstrate that the initial body coordinates of position (relative to the hind-legs ground-contact points are dominant in predicting the jumps’ azimuth and elevation angles. We also report a strong linear correlation between the jumps’ pitch-angular-velocity and flight initiation timing, such that head downwards rotations lead to earlier wing opening. In addition to offering important insights into the bio-mechanical principles of locust jumping and flight initiation, the findings from this study will be used in designing future prototypes of a bio-inspired miniature jumping robot that will be employed in animal behaviour studies and environmental monitoring applications.

Study of some significant parameters about the dynamic of the arms to evaluate the vertical jump in volleyball athletes, category 13-15 from the sport school Ormani Arenado Llonch

Directory of Open Access Journals (Sweden)

Enrique Henríquez Hernández

2016-04-01

Full Text Available To improve the yield in the vertical jump for many scientists, trainers and athletes has been and it continues being a polemic objective in the training for the volleyball players keeping in mind the participation that has this task motorboat in question, without doubts the Cuban School of Volleyball keeping in mind the characteristics of our players it has potentialized the saltabilidad of the jugadoras there is inclination of the years for it becomes it necessary to study and to evaluate the capacity miodinámica of the musculature of the inferior members to give continuity to this problem takes like sample in our study the athletes of the category 13-15 years of the EIDE of Pinegrove of the River to which you/they were carried out a traverse study in the stage of general physical preparation where you study the restored miodinámica of the inferior members in different laboratory test Squat Jump and I jump with against movements starting from a contact doormat built in Pinegrove of the River, field test like long jump without impulse, test of Power of Lewis, test of relative force for inferior members, being significant securities of correlation. Starting from the results individual suggestions were offered for the training of this athletes.

Teen dating violence: building a research program through collaborative insights.

Science.gov (United States)

Mulford, Carrie F; Blachman-Demner, Dara R

2013-06-01

The National Institute of Justice (NIJ) has an emerging portfolio of research in the area of teen dating violence (also known as adolescent relationship abuse). This article begins with a discussion of the developments that prompted NIJ to focus on teen dating violence. Next, the article highlights specific accomplishments and contributions that NIJ has made to helping develop knowledge and scientific understanding of adolescent relationship abuse, particularly around the prevention of teen dating violence perpetration and victimization. This is followed by a presentation of some of the key findings from NIJ-funded research. We then move to a discussion of some of the complex issues around definition, measurement and research methods and how NIJ has been involved in addressing those issues. The article concludes with some thoughts about the intersection of teen dating violence research, policy, and practice and highlights several research gaps that are in need of additional attention.

Variability of Plyometric and Ballistic Exercise Technique Maintains Jump Performance.

Science.gov (United States)

Chandler, Phillip T; Greig, Matthew; Comfort, Paul; McMahon, John J

2018-06-01

Chandler, PT, Greig, M, Comfort, P, and McMahon, JJ. Variability of plyometric and ballistic exercise technique maintains jump performance. J Strength Cond Res 32(6): 1571-1582, 2018-The aim of this study was to investigate changes in vertical jump technique over the course of a training session. Twelve plyometric and ballistic exercise-trained male athletes (age = 23.4 ± 4.6 years, body mass = 78.7 ± 18.8 kg, height = 177.1 ± 9.0 cm) performed 3 sets of 10 repetitions of drop jump (DJ), rebound jump (RJ) and squat jump (SJ). Each exercise was analyzed from touchdown to peak joint flexion and peak joint flexion to take-off. Squat jump was analyzed from peak joint flexion to take-off only. Jump height, flexion and extension time and range of motion, and instantaneous angles of the ankle, knee, and hip joints were measured. Separate 1-way repeated analyses of variance compared vertical jump technique across exercise sets and repetitions. Exercise set analysis found that SJ had lower results than DJ and RJ for the angle at peak joint flexion for the hip, knee, and ankle joints and take-off angle of the hip joint. Exercise repetition analysis found that the ankle joint had variable differences for the angle at take-off, flexion, and extension time for RJ. The knee joint had variable differences for flexion time for DJ and angle at take-off and touchdown for RJ. There was no difference in jump height. Variation in measured parameters across repetitions highlights variable technique across plyometric and ballistic exercises. This did not affect jump performance, but likely maintained jump performance by overcoming constraints (e.g., level of rate coding).

Influence of magnetic history on flux jump fields

International Nuclear Information System (INIS)

Sosnowski, J.

1986-01-01

A formalism describing the fields at which flux jumps occur in hard superconductors has been confirmed by the description of an experimentally observed shift of flux jump fields in the second hysteresis loop of a Nb 3 Al superconducting sample. By fitting the theoretical model to experimental data, values of the proportionality parameter between the stability limit and the flux jump field, the first stability limit, and the first penetration field have been estimated

Timeless Approach to Quantum Jumps

Directory of Open Access Journals (Sweden)

Ignazio Licata

2015-10-01

Full Text Available According to the usual quantum description, the time evolution of the quantum state is continuous and deterministic except when a discontinuous and indeterministic collapse of state vector occurs. The collapse has been a central topic since the origin of the theory, although there are remarkable theoretical proposals to understand its nature, such as the Ghirardi–Rimini–Weber. Another possibility could be the assimilation of collapse with the now experimentally well established phenomenon of quantum jump, postulated by Bohr already in 1913. The challenge of nonlocality offers an opportunity to reconsider the quantum jump as a fundamental element of the logic of the physical world, rather than a subsidiary accident. We propose here a simple preliminary model that considers quantum jumps as processes of entry to and exit from the usual temporal domain to a timeless vacuum, without contradicting the quantum relativistic formalism, and we present some potential connections with particle physics. Quanta 2015; 4: 10–26.

A COMPARISON OF PAIRS FIGURE SKATERS IN REPEATED JUMPS

Directory of Open Access Journals (Sweden)

William A. Sands

2012-03-01

Full Text Available Trends in pairs figure skating have shown that increasingly difficult jumps have become an essential aspect of high-level performance, especially in the latter part of a competitive program. We compared a repeated jump power index in a 60 s repeated jump test to determine the relationship of repeated jump test to competitive rank and to measure 2D hip, knee, and ankle angles and angular velocities at 0, 20, 40, and 60 s. Eighteen National Team Pairs Figure Skaters performed a 60 s repeated jump test on a large switch-mat with timing of flight and ground durations and digital video recording. Each 60-s period was divided into 6, 10-s intervals, with power indexes (W/kg calculated for each 10-s interval. Power index by 10-s interval repeated measures ANOVAs (RMANOVA showed that males exceeded females at all intervals, and the highest power index interval was during 10 to 20 s for both sexes. RMANOVAs of angles and angular velocities showed main effects for time only. Power index and jumping techniques among figure skaters showed rapid and steady declines over the test duration. Power index can predict approximately 50% of competitive rank variance, and sex differences in jumping technique were rare

Relief-oriented use of marijuana by teens

Directory of Open Access Journals (Sweden)

Johnson Joy L

2009-04-01

Full Text Available Abstract Background There are indications that marijuana is increasingly used to alleviate symptoms and for the treatment of a variety of medical conditions both physical and psychological. The purpose of this study was to describe the health concerns and problems that prompt some adolescents to use marijuana for therapeutic reasons, and their beliefs about the risks and benefits of the therapeutic use of marijuana. Methods As part of a larger ethnographic study of 63 adolescents who were regular marijuana users, we analyzed interviews conducted with 20 youth who self-identified as using marijuana to relieve or manage health problems. Results Thematic analysis revealed that these teens differentiated themselves from recreational users and positioned their use of marijuana for relief by emphasizing their inability to find other ways to deal with their health problems, the sophisticated ways in which they titrated their intake, and the benefits that they experienced. These teens used marijuana to gain relief from difficult feelings (including depression, anxiety and stress, sleep difficulties, problems with concentration and physical pain. Most were not overly concerned about the risks associated with using marijuana, maintaining that their use of marijuana was not 'in excess' and that their use fit into the realm of 'normal.' Conclusion Marijuana is perceived by some teens to be the only available alternative for teens experiencing difficult health problems when medical treatments have failed or when they lack access to appropriate health care.

Dissipative - free jumps for the magnetoacoustic branch of cold plasma motions

International Nuclear Information System (INIS)

Bakholdin, I.B.

2000-01-01

Dissipative-free jumps were studied in hydrodynamic model of cold plasma moving with the rate close to magnetoacoustic one. The jumps for the generalized Korteweg-de Vries equation with similar nonlinear and dispersion properties were studied. Among them there were jumps with emission and solution type jumps. Furthermore, the numerical investigation into the initial break decomposition in cold plasma confirmed the validity of assumption that in the given type of jumps as in case of the generalized Korteweg-de Vries equation. Paper describes the analytical method enabling to forecast the structure nature of such jumps in the general case [ru

Reducing the Teen Birth Rate. KIDS COUNT Indicator Brief

Science.gov (United States)

Shore, Rima; Shore, Barbara

2009-01-01

Teen childbearing affects young people at both ends of childhood. When teens have children, their own health may be jeopardized and their chances to build productive lives are often diminished. Compared to women who postpone childbearing until they are older, teenage mothers are more likely to drop out of school and to live in poverty. At the same…

Designing Public Library Websites for Teens: A Conceptual Model

Science.gov (United States)

Naughton, Robin Amanda

2012-01-01

The main goal of this research study was to develop a conceptual model for the design of public library websites for teens (TLWs) that would enable designers and librarians to create library websites that better suit teens' information needs and practices. It bridges a gap in the research literature between user interface design in human-computer…

Help-Seeking and Help-Giving for Teen Dating Violence

Science.gov (United States)

Weisz, Arlene N.; Black, Beverly M.

2009-01-01

This article is based on numerous research projects conducted by the authors on adolescent dating violence. It reviews the results of those projects as they relate to how teens seek help for dating violence and how teens provide help to their friends in violent dating relationships. It concludes with helpful strategies for adults who work with…

Confessions of Former Teen Program Participants: Two Decades Later

Science.gov (United States)

Flores, Fabrizio; Wyrick, Gabrielle; Zwicky, Calder

2014-01-01

As a companion to more data-driven articles and studies that consider the long-term impact of art museum teen programs on alumni, this article takes the form of a person to person interview with two founding teen members of important programs that emerged in the 1990s. Talking candidly about the impact of their program participation, Calder Zwicky…

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

DEFF Research Database (Denmark)

Bollerslev, Tim; Todorov, Viktor

We provide a new framework for estimating the systematic and idiosyncratic jump tail risks in financial asset prices. The theory underlying our estimates are based on in-fill asymptotic arguments for directly identifying the systematic and idiosyncratic jumps, together with conventional long...... market portfolio, we find that the distributions of the systematic and idiosyncratic jumps are both generally heavy-tailed and not necessarily symmetric. Our estimates also point to the existence of strong dependencies between the market-wide jumps and the corresponding systematic jump tails for all...... of the stocks in the sample. We also show how the jump tail dependencies deduced from the high-frequency data together with the day-to-day temporal variation in the volatility are able to explain the “extreme” dependencies vis-a-vis the market portfolio....

Numerical study of laminar, standing hydraulic jumps in a planar geometry.

Science.gov (United States)

Dasgupta, Ratul; Tomar, Gaurav; Govindarajan, Rama

2015-05-01

We solve the two-dimensional, planar Navier-Stokes equations to simulate a laminar, standing hydraulic jump using a Volume-of-Fluid method. The geometry downstream of the jump has been designed to be similar to experimental conditions by including a pit at the edge of the platform over which liquid film flows. We obtain jumps with and without separation. Increasing the inlet Froude number pushes the jump downstream and makes the slope of the jump weaker, consistent with experimental observations of circular jumps, and decreasing the Reynolds number brings the jump upstream while making it steeper. We study the effect of the length of the domain and that of a downstream obstacle on the structure and location of the jump. The transient flow which leads to a final steady jump is described for the first time to our knowledge. In the moderate Reynolds number regime, we obtain steady undular jumps with a separated bubble underneath the first few undulations. Interestingly, surface tension leads to shortening of wavelength of these undulations. We show that the undulations can be explained using the inviscid theory of Benjamin and Lighthill (Proc. R. Soc. London, Ser. A, 1954). We hope this new finding will motivate experimental verification.

Perceptions of injury prevention and familial adjustment among mothers of teen parents.

Science.gov (United States)

Barczyk, Amanda N; Duzinski, Sarah V; Brown, Juliette M; Lawson, Karla A

2015-02-01

Injury is a leading cause of death for infants and children. Teen mothering has been shown to put children at increased risk of injury. The mothers of teen parents often play a predominant role in the lives and caregiving of the children born to their children. This article presents the findings of three focus groups conducted with 21 mothers of teen parents. Grounded theory methodology was used to explore family dynamics and how they relate to injury prevention beliefs and practices regarding infants and children. Our findings revealed the difficulty mothers of teen parents and the teens themselves have in adjusting to the knowledge of the pregnancy. Unique barriers to injury prevention were also uncovered. Our findings provide evidence for the need of a multigenerational approach to programs aimed at improving the safety and well-being of children in this context. Copyright © 2014 Elsevier Ltd. All rights reserved.

Measurement of K-shell jump ratios and jump factors for some elements in 76≤Z≤92 using EDXRF spectrometer

International Nuclear Information System (INIS)

Kaya, N.; Apaydin, G.; Tirasoglu, E.

2011-01-01

This article presents experimental values of the K-shell jump factor and jump ratio (ratio of the K-shell photoionization cross section to the photoionization cross section of the rest of the atom at the K edge) for some elements in 76≤Z≤92 using an energy dispersive X-ray fluorescence (EDXRF) spectrometer and compares those values with the theoretical ones giving reasonable agreement. The experimental values have been determined using the fluorescence parameters: K α production cross sections, K β /K α X-rays intensity ratios, total atomic attenuation cross sections, etc. To the best of our knowledge, K-shell jump ratios and jump factors have been measured without having any data on K edge for the first time in these elements. The results have been plotted versus atomic number.

Teen responses when a younger school-age sibling has been bullied

Science.gov (United States)

Honig, Alice Sterling; Zdunowski-Sjoblom, Nicole

2015-01-01

The prevalence of bullying among children, and the sometimes tragic consequences as a result, has become a major concern in schools. The larger research for this study reported on in-depth interviews with 28 elementary and middle school-age boys and girls (7–12 years) who had experienced various forms of bullying and relational aggression by their peers, mostly on school grounds, and the responses of their parents and teachers. Responses of the children's teen siblings to the younger child's revelations of being bullied are the focus of this report. In-depth interviews with each teen sibling (n = 28) and with each bullied child revealed how the children viewed the teen siblings' supportive strategies. Almost all the children (89%) reported that their older siblings talked with them and offered advice. The teen siblings shared with the younger ones that they too (71%) had been bullied, or they knew someone who had been bullied (18%). Teens gave the advice to ‘bully back’ to 11% and advice to ‘tell someone’ to 32% of the younger children. The children felt quite positive about their older siblings' advice (89%), which did differ depending on the bullied child's gender. Teen siblings gave advice to ‘avoid bullies’ to 77% of female and to 27% of male younger children. PMID:25931644

Temperature jump boundary conditions in radiation diffusion

International Nuclear Information System (INIS)

Alonso, C.T.

1976-12-01

The radiation diffusion approximation greatly simplifies radiation transport problems. Yet the application of this method has often been unnecessarily restricted to optically thick regions, or has been extended through the use of such ad hoc devices as flux limiters. The purpose of this paper is to review and draw attention to the use of the more physically appropriate temperature jump boundary conditions for extending the range of validity of the diffusion approximation. Pioneering work has shown that temperature jump boundary conditions remove the singularity in flux that occurs in ordinary diffusion at small optical thicknesses. In this review paper Deissler's equations for frequency-dependent jump boundary conditions are presented and specific geometric examples are calculated analytically for steady state radiation transfer. When jump boundary conditions are applied to radiation diffusion, they yield exact solutions which are naturally flux- limited and geometry-corrected. We believe that the presence of temperature jumps on source boundaries is probably responsible in some cases for the past need for imposing ad hoc flux-limiting constraints on pure diffusion solutions. The solution for transfer between plane slabs, which is exact to all orders of optical thickness, also provides a useful tool for studying the accuracy of computer codes

Andragogy for Teen and Young Adult Learners with Intellectual Disabilities: Learning, Independence, and Best Practices

Science.gov (United States)

Bowman, Stephanie L.; Plourde, Lee A.

2012-01-01

Teens and young adults with Intellectual Disabilities (ID) meet the criteria of teen and adult learners chronologically, but may be deficient in many other areas of teen and adult learning. The spectrum of intellectual and adaptive capabilities among teens and adults with ID is vast, with each individual being unique. There are specific teaching…

Extending the Five-Foot Bookshelf: More Essential Books for Professionals Who Serve Teens.

Science.gov (United States)

Rosenzweig, Susan

2000-01-01

Provides annotated bibliographies for five books that are recommended professional reading for librarians serving teens. Topics include American Indian stereotypes in the media; a leadership guide for school library media specialists; views of teens; how teens who are different are often outcasts; and tips for public library young adult services.…

A feasibility study to assess the effectiveness of safe dates for teen mothers.

Science.gov (United States)

Herrman, Judith W; Waterhouse, Julie K

2014-01-01

To determine the effectiveness of the adapted Safe Dates curriculum as an intervention for pregnant and/or parenting teens to prevent teen dating violence (TDV). This pre-/posttest, single-sample study provided a means to assess the effectiveness of an adapted Safe Dates curriculum for teen mothers. The adapted Safe Dates curriculum was implemented in three schools designed for the unique needs of teens who are pregnant and/or parenting. The final sample of 41 teen participants, with a mean age of 16.27, completed 80% of the curriculum and two of the three assessments. Most of the teens were pregnant during participation in the curriculum, and six had infants between age 1 and 3 months. The teen mothers completed the pretest, participated in the 10-session adapted Safe Dates curriculum, and completed the posttest at the end of the program and 1 month after program completion. The pre/posttest was adapted from the Safe Dates curriculum-specific evaluation instrument. Senior, undergraduate nursing students were trained in and implemented the curriculum. Participation in the adapted Safe Dates program yielded significant differences in the areas of responses to anger, gender stereotyping, awareness of resources for perpetrators and victims, and psychological violence perpetration. This adapted program may be effective in changing selected outcomes. The implementation of a larger scale, experimental/control group study may demonstrate the program's efficacy at reducing the incidence of TDV among teen mothers. © 2014 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

Teen Drinking and Driving – What You Need to Know

Centers for Disease Control (CDC) Podcasts

This podcast is based on the October 2012 CDC Vital Signs report. It’s illegal and dangerous for teens to drink any alcohol and then drive. Still, one in ten high school teens drank and got behind the wheel in 2011. A parent-teen driving agreement is a good way for parents to help keep young drivers safe behind the wheel.

Optimizing the Distribution of Leg Muscles for Vertical Jumping.

Directory of Open Access Journals (Sweden)

Jeremy D Wong

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

Optimizing the Distribution of Leg Muscles for Vertical Jumping

Science.gov (United States)

Wong, Jeremy D.; Bobbert, Maarten F.; van Soest, Arthur J.; Gribble, Paul L.; Kistemaker, Dinant A.

2016-01-01

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