The Effect of Ballistic Training on Punch Kinetics and Endurance in Trained Boxers

Strength and conditioning coaches are becoming increasingly aware of the importance of sport-specific movements when designing and implementing training programs for power development. The use of ballistic training (BT) for combat athletes, such as boxers, is growing in popularity, however there is a paucity of research on the effect of this method on punching kinetics and endurance. This study examined changes in punch kinetics and endurance following a six-week BT intervention. Forty-five participants (male n = 28, female n = 17; mean age = 28 ± 6.0 years, height = 1.8 ± .1 m, mass = 83.4 ± 15.2 kg) with a mean boxing experience of 11.3 ± 7.9 months were recruited for the study. Participants were sorted by self-reported boxing experience and then randomly assigned to either a control (CONTR) or experimental (BT) group. Participants in the BT group completed supervised training involving loaded ballistic exercises twice per week for six weeks. CONTR group participants completed supervised training twice per week for six weeks, with unloaded exercises performed at a slow and controlled tempo. Participants’ punch kinetics and endurance were examined before and after the 6-week training period using force plates. Results’ showed a 30% increase in maximum punch force (PFmax; p \u3c 0.001) and a 44% increase in rate of force development (RFD; p \u3c 0.001) in the BT group, throughout the 6-week training period. In contrast, CONTR group participants showed no change in PFmax and RFD over the course of the study. Increases in PFmax occurred despite no significant change in lead and rear foot forces. Although PFmax, the average of the PFmax across all punches within the first and third minutes, was shown to significantly increase in the BT group, a similar decrement in force output was observed between both groups post-intervention. Thus, BT exhibited little effect on punching endurance. The ability to produce high power outputs has been identified as a key variable in boxing performance. Consequently, power development should be a priority for strength coaches working with combat athletes. These coaches should consider how punch kinematics relates to force transmission. A distinct advantage of BT is its versatility as a training stimulus, whereby exercises aim to enhance force characteristics while replicating the movement patterns of the sporting task. The present data supports this notion and the inclusion of BT within a speed-strength phase prior to competition should be considered by coaches working with combat athletes

The four seam trawl nets operated off Cochin: an analysis of the design aspects: the integration of the various parts of trawl

A study has been made of 22 different designs of four seam trawls operated at Cochin for shrimp trawling. Formulae for the relations between the different parts of the nets have been derived

Quantifying Sexually Explicit Language

Detecting the degree and character of sexually explicit textual content is a feasible and potentially useful enterprise. Such a facility may assist in preventing child exploitation, for example, by automating the detection of the highly sexualised content of on-line grooming, and may be beneficial in SMS for detecting offensive sexting. In addition, an ability to determine the nature and ‘strength’ of sexually explicit content would prove helpful in contexts where students, trainees or other professionals need to be exposed to sexually explicit language in documents. In such settings, we might deploy such detection and quantification toward managing the content, for instance, by means of progressive ‘neutralisation’. In the following, we elaborate upon the relevance of such quantification and describe a variety of steps toward neutralisation

Determination of Li-6 -- He-4 interaction from multi-energy scattering data

We present the first successful potential model description of Li-6 -- He-4 scattering. The differential cross-sections for three energies and the vector analyzing powers for two energies were fitted by a single potential with energy dependent imaginary components. An essential ingredient is a set of Majorana terms in each component. The potential was determined using a recently developed direct data-to-potential inversion method which is a generalisation of the IP S-matrix-to-potential inversion algorithm. We discuss the problems related to this phenomenological approach, and discuss the relationship of our results to existing and future theories.Comment: 9 pages plain LaTeX, 6 postscript figue

A conceptual model to predict social engineering victims

Social engineering (SE) attacks are a serious threat to online users and might subject people to different kinds of harm. Despite increased concern with this risk, there has been little research activity focused upon social engineering in the potentially rich hunting ground of social networks. The number of victims of social engineering attacks will be decreased if the users' detection ability has improved. Yet, this improvement of the user's detection behaviour can't be occurred without investigating the users' weakness points. The present study develops a conceptual model to test the factors that influence social networks users' judgment of social engineering-based attacks in order to identify the weakest points of users' detection behaviour which also help to predict vulnerable individuals

Diversity of human lip prints: a collaborative study of ethnically distinct world populations

Background: Cheiloscopy is a comparatively recent counterpart to the long established dactyloscopic studies. Ethnic variability of these lip groove patterns has not yet been explored. Aim: This study was a collaborative effort aimed at establishing cheiloscopic variations amongst modern human populations from four geographically and culturally far removed nations: India, Saudi Arabia, Spain and Nigeria. Subjects and methods: Lip prints from a total of 754 subjects were collected and each was divided into four equal quadrants. The patterns were classified into six regular types (A?F), while some patterns which could not be fitted into the regular ones were segregated into G groups (G-0, G-1, G-2). Furthermore, co-dominance of more than one pattern type in a single quadrant forced us to identify the combination (COM, G-COM) patterns. Results and conclusion: The remarkable feature noted after compilation of the data included pattern C (a bifurcate/branched prototype extending the entire height of the lip) being a frequent feature of the lips of all the populations studied, save for the Nigerian population in which it was completely absent and which showed a tendency for pattern A (a vertical linear groove) and a significantly higher susceptibility for combination (COM) patterns. Chi-square test and correspondence analysis applied to the frequency of patterns appearing in the defined topographical areas indicated a significant variation for the populations studied

The 1:1 resonance in Extrasolar Systems: Migration from planetary to satellite orbits

We present families of symmetric and asymmetric periodic orbits at the 1/1 resonance, for a planetary system consisting of a star and two small bodies, in comparison to the star, moving in the same plane under their mutual gravitational attraction. The stable 1/1 resonant periodic orbits belong to a family which has a planetary branch, with the two planets moving in nearly Keplerian orbits with non zero eccentricities and a satellite branch, where the gravitational interaction between the two planets dominates the attraction from the star and the two planets form a close binary which revolves around the star. The stability regions around periodic orbits along the family are studied. Next, we study the dynamical evolution in time of a planetary system with two planets which is initially trapped in a stable 1/1 resonant periodic motion, when a drag force is included in the system. We prove that if we start with a 1/1 resonant planetary system with large eccentricities, the system migrates, due to the drag force, {\it along the family of periodic orbits} and is finally trapped in a satellite orbit. This, in principle, provides a mechanism for the generation of a satellite system: we start with a planetary system and the final stage is a system where the two small bodies form a close binary whose center of mass revolves around the star.Comment: to appear in Cel.Mech.Dyn.Ast

On the dynamics of Extrasolar Planetary Systems under dissipation. Migration of planets

We study the dynamics of planetary systems with two planets moving in the same plane, when frictional forces act on the two planets, in addition to the gravitational forces. The model of the general three-body problem is used. Different laws of friction are considered. The topology of the phase space is essential in understanding the evolution of the system. The topology is determined by the families of stable and unstable periodic orbits, both symmetric and non symmetric. It is along the stable families, or close to them, that the planets migrate when dissipative forces act. At the critical points where the stability along the family changes, there is a bifurcation of a new family of stable periodic orbits and the migration process changes route and follows the new stable family up to large eccentricities or to a chaotic region. We consider both resonant and non resonant planetary systems. The 2/1, 3/1 and 3/2 resonances are studied. The migration to larger or smaller eccentricities depends on the particular law of friction. Also, in some cases the semimajor axes increase and in other cases they are stabilized. For particular laws of friction and for special values of the parameters of the frictional forces, it is possible to have partially stationary solutions, where the eccentricities and the semimajor axes are fixed.Comment: Accepted in Celestial Mechanics and Dynamical Astronom

Evidence of Final-State Suppression of High-p_T Hadrons in Au + Au Collisions Using d + Au Measurements at RHIC

Transverse momentum spectra of charged hadrons with ${p_{T} <}$ 6 GeV/c have been measured near mid-rapidity (0.2 $< \eta <$ 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at ${\sqrt{s_{_{NN}}} = \rm {200 GeV}}$. The spectra for different collision centralities are compared to ${p + \bar{p}}$ collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-$p_{T}$ region (${>2}$ GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-$p_{T}$ yields. These measurements suggest a large energy loss of the high-$p_{T}$ particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions.Comment: 3 pages, 4 figures, International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, German

Non-Random mtDNA Segregation Patterns Indicate a Metastable Heteroplasmic Segregation Unit in m.3243A>G Cybrid Cells

Many pathogenic mitochondrial DNA mutations are heteroplasmic, with a mixture of mutated and wild-type mtDNA present within individual cells. The severity and extent of the clinical phenotype is largely due to the distribution of mutated molecules between cells in different tissues, but mechanisms underpinning segregation are not fully understood. To facilitate mtDNA segregation studies we developed assays that measure m.3243A>G point mutation loads directly in hundreds of individual cells to determine the mechanisms of segregation over time. In the first study of this size, we observed a number of discrete shifts in cellular heteroplasmy between periods of stable heteroplasmy. The observed patterns could not be parsimoniously explained by random mitotic drift of individual mtDNAs. Instead, a genetically metastable, heteroplasmic mtDNA segregation unit provides the likely explanation, where stable heteroplasmy is maintained through the faithful replication of segregating units with a fixed wild-type/m.3243A>G mutant ratio, and shifts occur through the temporary disruption and re-organization of the segregation units. While the nature of the physical equivalent of the segregation unit remains uncertain, the factors regulating its organization are of major importance for the pathogenesis of mtDNA diseases