The results of the laboratory research concerning a dependence of flicker vision on voltage fluctuations are presented in the paper. The research was realized on a designed measuring stand, which included an examined light source, a voltage generator with amplitude modulation supplying the light source and a positioning system of the observer with respect to the observed surface. In this research, the following light sources were used: one incandescent lamp and four LED luminaires by different producers. The research results formulate a conclusion concerning the description of the influence of voltage fluctuations on flicker viewing for selected light sources. The research results indicate that LED luminaires are less susceptible to voltage fluctuations than incandescent bulbs and that flicker vision strongly depends on the type of LED source.

Esej audiowizualny-w stronę historii W ostatnich latach w piśmiennictwie filmoznawczym, nie tylko zresztą akademickim, ale także na obszarze popularnej krytyki filmowej, niezwykle często pojawiają się teksty poświęcone zagadnieniu eseju filmowego 1. Pojęcie to zostało oczywiście zaanektowane na obszar kina z literatury. Pozwoliło to przenieść część rozważań poświęconych esejowi literackiemu wprost na grunt badań nad filmem. W ten sposób badacze tej formy uzyskali szereg narzędzi ułatwiających opis tego oryginalnego zjawiska. Jednocześnie esej filmowy odziedziczył jednak po swoim literackim odpowiedniku problem związany z jego definiowalnością. Rozpiętość form literackich określanych mianem esejów, od Prób Montaigne'a, przez powieści Tomasza Manna czy choćby teksty Rolanda Barthes'a, sprawiła, że utrudnione-jeśli nie niemożliwe-stało się wskazanie inwariantnych wyznaczników gatunkowych tej formy. Pojęciem eseju filmowego posłużył się prawdopodobnie jako pierwszy Hans Richter (w roku 1940)-definiując go jako nową formę dokumentalizmu, zdolną do przedstawiania abstrakcyjnych pojęć i idei. Jako przykład wskazywał filmy klasyków zaangażowanego społecznie dokumentalizmu przełomu lat dwudziestych i trzydziestych. Richter akcentował odchodzenie w tych filmach od chronologii w prezentowaniu wydarzeń i poświęcenie wierności nieupozorowanej rzeczywistości wczesnych aktualności filmowych, na rzecz wszelkich technik filmowych, które mogą dopomóc w zilustrowaniu dyskursu autorskiego-a więc także fikcji-rekonstrukcji, inscenizacji, fabularyzacji 2. Trzeba 1 Wśród ważniejszych prac warto wymienić monografię Laury Rascaroli,

The aim of this study was to assess whether cycling training may influence quality of functional movement patterns and dynamic postural control. We also sought to determine if the Functional Movement Screen and Lower Quarter Y-balance tests could be predictive of injury risk among adolescent road cyclists. Twenty-three male road cyclists, aged 15–18 years, were involved in the study. Quality of functional movement patterns was assessed using the Functional Movement Screen test (FMS). Dynamic postural control was evaluated using the Lower Quarter Y-balance test (YBT-LQ). Information on injury occurrence was collected through a retrospective survey. The results showed the highest percentage of scores equalling 0 and 1 (>30% in total) in two FMS component tests: the hurdle step and trunk stability push-up. The results also demonstrated a low injury predictive value of the Functional Movement Screen (cut-off <14/21 composite score) and the Lower Quarter Y-balance test (cut-off <94% composite score and >4 cm reach distance asymmetry) in adolescent road cyclists. The most important information obtained from this study is that youth road cyclists may have functional deficits within the lumbo-pelvic-hip complex and the trunk, while neither the FMS nor the YBT-LQ test are not recommended for injury risk screening in cyclists.

No abstract

Background: Maximal sprinting speed (MSS) is an essential component of success in many sports. Currently, many systems are used to accurately evaluate athletes’ MSS, including laser or radar guns, single- or dual-beam photocells, high-speed cameras, and high-frequency global positioning systems. However, the cost of these devices may be an obstacle to their implementation into practice. The least expensive but most likely less accurate alternative method of MSS evaluation is the hand-held time measurement of a 30m flying-start sprint. Therefore, the aim of the study was to assess the concurrent validity and inter-rater reliability o the hand-held method of MSS measurement. Materials and Methods: The study involved 3 experienced raters and 18 amateur runners. Runners performed 2-3 trials of the 30m maximal flying-start sprint. In total, 40 observations were collected. Each sprint time was measured simultaneously by raters using a hand-held stopwatch and an electronic timing system. Criterion validity (hand-held vs. electronic timing) was assessed using linear regression analysis. Inter-rater reliability between hand-held timers was evaluated using interclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimal detectable change (MDC). Results: Results showed that single and average hand-held methods are affected by -0.17 to -0.07m·s-1 (-2.5 to -1.6%) and -0.12m·s- 1 (-1.7%) errors, respectively. Linear regression analysis parameters (free parameter not statistically significant, directional coefficient 0.994-1.057, standard error of estimation 0.073-0.125, R2 0.981-0.994) indicated statistically excellent absolute agreement between a hand-held (single and average) and electronic timing. ICCs of 0.980-0.994, SEM of 0.12m·s-1 (1.87%), and MDC of 0.34m·s-1 (5.18%) indicated statistically excellent absolute agreement and consistency for single and average measurements between hand-held timers. Conclusion: The proposed manual method of MSS measurement underestimates athletes’ speed performance. Moreover, the hand-held 30m flying-start sprint time measurement is affected by a 2% error, and a minimum 5% time change in an individual athlete demonstrates that the change is not simply attributable to measurement error.