Three-dimensional assessment of squats and drop jumps using the Microsoft Xbox One Kinect: Reliability and validity

The Microsoft Xbox One Kinect? (Kinect V2) contains a depth camera that can be used to manually identify anatomical landmark positions in three-dimensions independent of the standard skeletal tracking, and therefore has potential for low-cost, time-efficient three-dimensional movement analysis (3DMA). This study examined inter-session reliability and concurrent validity of the Kinect V2 for the assessment of coronal and sagittal plane kinematics for the trunk, hip and knee during single leg squats (SLS) and drop vertical jumps (DVJ). Thirty young, healthy participants (age = 23 ± 5yrs, male/female = 15/15) performed a SLS and DVJ protocol that was recorded concurrently by the Kinect V2 and 3DMA during two sessions, one week apart. The Kinect V2 demonstrated good to excellent reliability for all SLS and DVJ variables (ICC ≥ 0.73). Concurrent validity ranged from poor to excellent (ICC = 0.02 to 0.98) during the SLS task, although trunk, hip and knee flexion and two-dimensional measures of knee abduction and frontal plane projection angle all demonstrated good to excellent validity (ICC ≥ 0.80). Concurrent validity for the DVJ task was typically worse, with only two variables exceeding ICC = 0.75 (trunk and hip flexion). These findings indicate that the Kinect V2 may have potential for large-scale screening for ACL injury risk, however future prospective research is required.     

Broadcasting and Telecommunications

G.W.A. Dummer's Electronic Inventions: 1745-1976 (Oxford, England: Pergamon Press, 1976—£5.50 or $10.00)

Carl Dreher's Sarnoff: An American Success (New York: Quadrangle/ New York Times Book Co., 1977—$12.50)

George W. Bartlett, ed. NAB Engineering Handbook (Washington: National Association of Broadcasters, 1975—$45.00; $30.00 to NAB and BEA members)

Richard Veith's Talk-Back TV: Two-Way Cable Television (Blue Ridge Summit. Pa.: TAB Books, 1976—$9.95/5.95)

Dan Rather with Mickey Herskowitz' The Camera Never Blinks: Adventures of a TV Journalist (New York: Morros, 1977—$10.00)

F. Gifford's Tape: A Radio News Handbook (New York: Hastings House, 1977—$12.95/6.95)

F. Earle Barcus' Children's Television: An Analysis of Programming and Advertising (New York: Praeger Special Studies, 1977—price not given, but likely around $18.00)

Douglas Davis and Allison Simmons' The New Television: A Public/Private Art (Cambridge, Mass.: MIT Press, 1977—$14.95)

The Videophile's Newsletter (Jim Lowe, 2014 South Magnolia Drive, Tallahassee, Fla. 32301—$7.50 for five issues)

Separations Procedures in the Telephone Industry: The Historical Origins of a Public Policy, by James W. Sichter (January 1977, Publication P-77-2, 146 pp. $23.40, paper)

The Communications Act Policy Toward Competition: The Sound of One Hand Clapping by Hamilton Loeb (March 1977, Working Paper W-77-1, 68 pp., $ 10.90)

Broadcasting: The Next Ten Years (New York: National Broadcasting Co., Department of Corporate Planning, 1977—apparently free on request, paper)

NFLCP Newsletter (P.O. Box 119, Cambridge, Mass. 02142—$7.50 annually, bimonthly; $15.00 to organizations)

Gary Gerani and Paul H. Schulman's Fantastic Television (New York: Harmony Books/Crown Publishers, 1977—$12.95/5.95)     

Knowledge bases in medicine: a review

Efforts to represent knowledge effectively have been central to progress in various aspects of medical informatics. These efforts range from relatively simple "electronic textbooks" to fairly sophisticated knowledge-based systems, which function as well as, or even better than, human experts faced with similar problems. Knowledge bases have been developed in many fields, but the relatively limited domains and structured language of medicine, as well as the importance of information in the provision of good medical care, have made research in medical knowledge representation an area of intense activity. This paper reviews representative knowledge bases and knowledge-based systems in medicine: electronic textbooks such as PDQ and the Hepatitis Knowledge Base (HKB), rule-based systems such as MYCIN, causal models (e.g., CASNET), and hypothesis- or frame-based systems, exemplified by PIP and INTERNIST-1. The paper describes the relationships among divergent approaches and provides a sense of current and future trends. It examines problems in knowledge-based systems, particularly in knowledge representation and acquisition, and the responses to these challenges. The latter include the use of domain-independent software shells for constructing knowledge bases, the adaptation and use of previously existing knowledge bases, and multiple uses of the same knowledge base for different purposes.     

Inter-participant variability in daily physical activity and sedentary time among male youth sport footballers: independent associations with indicators of adiposity and cardiorespiratory fitness

Participation in youth sport is assumed to promote and contribute towards more physically active lifestyles among children and adolescents. The aim of this study was to examine inter-participant variability in objectively measured habitual physical activity (PA) behaviours and sedentary time among youth sport participants and their implications for health. One-hundred-and-eighteen male youth sport footballers (Mean ± s = 11.72 ± 1.60) wore a GT3X accelerometer for 7 days. Average daily PA [min · day^?1, in light (LPA), moderate (MPA), vigorous (VPA) and combined moderate-to-vigorous (MVPA)] and sedentary time were calculated. Participants’ body mass index adjusted for age and sex (BMI–standard deviation score), per cent body fat (BF%), waist circumference and cardiorespiratory fitness were assessed. Results revealed that variability in daily PA behaviours and sedentary time (min · day^?1) was associated with BMI–standard deviation score [VPA (?), MVPA (?)], BF% [sedentary time (+), VPA (?), MVPA (?)], waist circumference [sedentary time (+), LPA (?)] and cardiorespiratory fitness [sedentary time (?), MPA (+), VPA (+), MVPA (+)]. Whilst sedentary time and MVPA were not related to health outcomes independent of one another, associations with markers of adiposity and cardiorespiratory fitness were stronger for sedentary time. Sedentary time was also significantly positively related to waist circumference independent of VPA. Results demonstrate inter-participant variability in habitual PA and sedentary time among youth sport participants which holds implications for their health. Thus, promoting PA and, in particular, reducing sedentary time may contribute towards the prevention of adverse health consequences associated with a physically inactive lifestyle for children and adolescents active in the youth sport context.     

On the Complexity of the Reduction of Multidimensional Data Models

In this paper, decomposition methods for multidimensional data hypercubes of OLAP systems are investigated. Criteria for reducing the computational complexity of the decomposition methods are presented and comparisons are made with the traditional solutions of multidimensional data analysis problems. Examples illustrating the application of these criteria to investigating the dynamics of computational complexity changes for specific types of reduction problems are considered.     

The nature of the modern information society

In this paper, a survey and critique are presented of the existing concepts of an information society. The concept of a “modern information society” is introduced. The main components of the information society concept are analyzed, i.e., information, information technologies and the IT workforce (specialists). Changes are considered in the main spheres of human activities. A broad definition of the modern information society is formulated.