Reference     

John Schmittroth Jr.  Martin Connors  Roberto Valdez  Elena Pernia  W.H. Wallace  M. Gordon 《Communication Booknotes Quarterly》2013,44(9):93-95

TELECOMMUNICATIONS SYSTEMS AND SERVICES DIRECTORY —ISSUE TWO, edited by John Schmittroth Jr. and Martin Connors (Detroit, Mich.: Gale Research, 1984--$170.00 for the first edition, being issued in three parts, paper)

THE BOOK PUBLISHING ANNUAL: HIGHLIGHTS, ANALYSES & TRENDS (New York: R.R. Bowker, 1984---$49.95)

THE COMPUTER AND BUSINESS EQUIPMENT INDUSTRY MARKETING DATA BOOK (Computer and Business Equipment Manufacturers Association, 311 First Street, N.W., Washington, D.C. 20001--price not given, paper)

THE SOCIAL AND ECONOMIC IMPACT OF VIDEOTEX, TELETEXT AND COMPUTERS: AN ANNOTATED BIBLIOGRAPHY, by Roberto Valdez, et al., and THE SOCIAL AND ECONOMIC IMPACT OF TELEPHONES by Elena Pernia, et al. (Honolulu, Hi.: East-West Center, 1984--price not given, but cost covers reproduction and postage, paper)

WHAT'S IN PRINT: THE SUBJECT GUIDE TO MICROCOMPUTER MAGAZINES, by W.H. Wallace (Blue Ridge Summit, Pennsylvania: TAB Books, 1984--price not given, paper)

DICTIONARY OF NEW INFORMATION TECHNOLOGY ACRONYMS, by M. Gordon, et al. (London: Kogan Page/Detroit: Gale Research, 1984--$56.00)

THE VIDEOTEX MARKETPLACE (Bethesda, Md.: Phillips Publishing, 1984--$97.00, paper)

A VIDEOTEX/TELETEXT BIBLIOGRAPHY (Videotex Industry Association, 1901 Ft. Myer Drive, Suite 200, Rosslyn, VA 22209--$25.00, paper)

AUDIO VIDEO MARKET PLACE: A MULTIMEDIA GUIDE 1984 (New York: R.R. Bowker, 1984--$45.00 paper)

THE INTERACTIVE CABLE TV HANDBOOK (Bethesda, Md.: Phillips Publishing, 1984--$97.00, paper)

COMPUTERIZED LITERATURE SEARCHING: RESEARCH STRATEGIES AND DATABASES, by Charles L. Gilreath (Boulder, Colo.: Westview, 1984--$25.00)  相似文献   

Landing techniques in volleyball     

Roberto Lobietti  Simon Coleman  Eduardo Pizzichillo  Franco Merni 《Journal of sports sciences》2013,31(13):1469-1476

Abstract

Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P < 0.05) were found between the sexes for block, set, and spike but not for the jump serve. The frequency of landings on one foot was related to court position and the trajectory of the sets: when spiking faster sets, the players were more likely to use a one-footed landing. The present results should help coaches and physiotherapists to devise appropriate training and prevention programmes, and reveal the need for further detailed biomechanical investigations of the relationships between landings and knee injuries.  相似文献   

Estimation of teacher practices based on text transcripts of teacher speech using a support vector machine algorithm     

Roberto Araya  Francisco Plana  Pablo Dartnell  Jorge Soto‐Andrade  Gina Luci  Elena Salinas  Marylen Araya 《British journal of educational technology : journal of the Council for Educational Technology》2012,43(6):837-846

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On the Wrong Side of the Tracks: Understanding the Effects of School Structure and Social Capital in the Educational Pursuits of Undocumented Immigrant Students     

Roberto G. Gonzales 《Peabody Journal of Education》2013,88(4):469-485

Over the last few years, increasing scholarly and media attention has been paid to the plight of undocumented immigrant college students. However, only a small fraction of undocumented youth actually moves on from high school to postsecondary opportunities. Indeed, the exclusion from financial aid eligibility and low family socioeconomic status severely limit undocumented students’ ability to matriculate to institutions of higher learning. But little is known about the ways in which school experiences shape postsecondary outcomes. This article focuses on the high school experiences of a sample of undocumented young adults and examines the ways in which school structures shape access to resources needed for postsecondary matriculation. In doing so, I argue that school-based networks are critical for success. However, these networks are fundamentally shaped by the school structure. This article draws from 78 in-depth life histories of undocumented Latino young adults in the Los Angeles metropolitan area. I incorporate a sample, stratified by educational experiences. The lived experiences of these young adults shed important light on the broader world in which they live and the ways in which immigration policies interact with school practices to shape success and failure.  相似文献   

The Short-Term Effects of a Computer-Based Pregnancy,STD, and HIV Prevention Program     

Anthony J. Roberto  Kellie E. Carlyle  Rick S. Zimmerman  Erin L. Abner  Pamela K. Cupp  Gary L. Hansen 《Communication quarterly》2013,61(1):29-48

A computer- and Internet-based intervention was designed to influence several variables related to the prevention of pregnancy, STDs, and HIV in rural adolescents. Three-hundred and thirty-eight tenth-graders enrolled in two rural public high schools participated in this field experiment. Results indicate that students in the experimental school had greater knowledge, greater condom negotiation efficacy, greater situational efficacy, and more favorable attitudes toward waiting to have sex than students in the control school. In tandem, the results suggest that computer-based programs may be a cost-effective and easily replicable means of providing teens with basic information and skills necessary to prevent pregnancy, STDs, and HIV.  相似文献   

Prevalence and Predictors of Cyberbullying Perpetration by High School Seniors     

Anthony J. Roberto  Jen Eden  Matthew W. Savage  Leslie Ramos-Salazar  Douglas M. Deiss 《Communication quarterly》2013,61(1):97-114

Cyberbullying is the deliberate and repeated misuse of communication technology by an individual or group to threaten or harm others. Guided largely by the communication skills deficiency model and previous research on cyberbullying, this study examins the effects of several predictor variables (i.e., verbal aggression, sex, risky behaviors, parental monitoring, parental limits, technology use, and scope of Internet activities) on cyberbullying perpetration. A total of 1,606 incoming freshmen at a large southwestern university completed an online survey measuring all predictor and dependent variables under investigation. Overall, 35% of these individuals reported that they had cyberbullied at least one person during their senior year of high school. Results indicated that verbal aggression, risky behaviors, and cyberbullying victimization emerged as significant predictors of cyberbullying perpetration. These results have important theoretical and practical implications for those interested in developing cyberbullying prevention interventions.  相似文献   

A dynamical systems approach for the submaximal prediction of maximum heart rate and maximal oxygen uptake     

Michael J. Mazzoleni  Claudio L. Battaglini  Kerry J. Martin  Erin M. Coffman  Jordan A. Ekaidat  William A. Wood  Brian P. Mann 《Sports Engineering》2018,21(1):31-41

This study examines the viability of utilizing a dynamical system model and heuristic parameter estimation algorithm to make predictions for maximum heart rate (\(\mathrm {HR_{max}}\)) and maximal oxygen uptake (\(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\)) using data collected from a submaximal testing protocol. \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) is widely considered to be the best single measurement of overall fitness in humans. When a \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) assessment is not available, \(\mathrm {HR_{max}}\) is often used to prescribe exercise intensities for training and rehabilitation. In the absence of maximal cardiopulmonary exercise testing (CPET), \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) are typically estimated using traditional submaximal prediction methods with well-known limitations and inaccuracies. For this study, 12 regularly exercising healthy young adult males performed a bout of maximal CPET on a cycle ergometer to determine their true \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\). Participants also performed a submaximal bout of exercise at varied intensities. A dynamical system model and heuristic parameter estimation algorithm were applied to the submaximal data to estimate the participants’ \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\). The submaximal predictions were evaluated by computing the coefficient of determination \({R^2}\) and the standard error of the estimate (SEE) through comparisons with the true maximal values for \(\mathrm {HR_{max}}\) (\({R^2 = 0.96}\), SEE = 2.4 bpm) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) (\({R^2 = 0.93}\), SEE = 2.1 mL kg\(^{-1}\) min\(^{-1}\)). The results from this study suggest that a dynamical system model and heuristic parameter estimation algorithm can provide accurate predictions for \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) using data collected from a submaximal testing protocol.  相似文献   

Physiological and anthropometric characteristics of top-level youth cross-country cyclists     

Alessandro Fornasiero  Aldo Savoldelli  Roberto Modena  Gennaro Boccia  Barbara Pellegrini  Federico Schena 《Journal of sports sciences》2018,36(8):901-906

In the literature there is a lack of data about the development of top level athletes in cross-country mountain biking (XCO). The purpose of this study was to analyze anthropometric and physiological characteristics of some of the best XCO bikers aged between 13 and 16. The study involved 45 bikers (26 males and 19 females) belonging to a youth national team. The evaluations, consisting of anthropometric measures, incremental cycling tests (VO_2max, PPO, P@RCP), and 30 s Wingate Tests (PMax, PMean), were conducted over a lapse of 4 years. Our findings showed in bikers, already at young age, a specific athletic profile advantageous for XCO performance. At the age of 16, just before entering the junior category and competing at international level, male and female bikers showed physiological values normalized to the body mass comparable to those reported in literature for high level athletes (VO_2max>70 and >60 ml/kg/min, PPO >6.5 and >5.5 W/kg, respectively in males and females). The production of high power-to-weight ratios and high peaks of anaerobic power attests the presence of highly developed aerobic and anaerobic systems in young XCO cyclists reflecting the high physiological demand of this sport.  相似文献   

Growth,functional capacities and motivation for achievement and competitiveness in youth basketball: an interdisciplinary approach     

Humberto Moreira Carvalho  Carlos E Gonçalves  Dave Collins  Roberto R Paes 《Journal of sports sciences》2018,36(7):742-748

The interaction of multiple influences on the path to sport success is not yet fully understood by sport scientists. In this study, we examined variation in body size, functional capacities and motivation for achievement, competitiveness and deliberate practice of youth basketball players associated with differences in biological maturity status, chronological age and years of training experience. Reflecting the importance of interactive effects, we examined the relationships between the psychological variables and functional capacities. Fifty-eight male basketball players aged 9.5 to 15.5 years were considered. Variables included chronological age, estimated age at peak height velocity, stature, body mass and sitting height by anthropometry; the Work and Family Orientation and Deliberate Practice Motivation Questionnaires were also used. Finally, the Line Drill test and Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) tests were used as functional capacities indicators for basketball. Variance components models derived from series of multilevel linear regression models revealed a substantial variation by maturity status for body size, functional capacities indicators, mastery and will to excel. The influence of estimated maturity status on mastery and will to excel was independent of age and years of experience. In contrast, no relationships were observed between psychological variables and functional capacities indicators. We conclude that growth-related changes are relevant to understanding players´ motivations for achievement, competitiveness and deliberate practice. This should be of interest to those involved in the selection and development of youth basketball players.  相似文献   

Validity and reliability of a novel optoelectronic device to measure movement velocity,force and power during the back squat exercise     

Roberto Laza-Cagigas  Mark Goss-Sampson  Eneko Larumbe-Zabala  Leke Termkolli 《Journal of sports sciences》2019,37(7):795-802

This study analysed the validity and reliability of a new optoelectronic device (Velowin) for the measurement of vertical displacement and velocity as well as to estimate force and mechanical power. Eleven trained males with Mean (SD) age = 27.4 (4.8) years, completed an incremental squat exercise test with 5 different loads (<30–90% of their 1?repetition maximum) while displacement and vertical velocity of the barbell were simultaneously measured using an integrated 3D system (3D motion capture system + force platform) and Velowin. Substantial to almost perfect correlation (concordance correlation coefficient = 0.75–0.96), root mean square error as coefficient of variation ±90% confidence interval ≤10% and good to excellent intraclass correlation coefficient = 0.84–0.99 were determined for all the variables. Passing and Bablock regression methods revealed no differences for average velocity. However, significant but consistent bias were determined for average or peak force and power while systematic and not proportional bias was found for displacement. In conclusion, Velowin, in holds of some potential advantages over traditionally used accelerometer or linear transducers, represents a valid and reliable alternative to monitor vertical displacement and velocity as well as to estimate average force and mechanical power during the squat exercise.  相似文献