RESPONSE CHARACTERISTICS OF A SQUAT - AND COUNTERMOVEMENT JUMP

NI

THE VARIABILITY OF VERTICAL GROUND REACTION FORCES DURING UNLOADED AND LOADED DROP JUMPING

The increase of the resistance of the movement - on the basis of the dynamic fundamental law F.t = m.v (Force Impulse = Change of the Kinematic Impulse) - can be achieved either by increasing the drop velocity v (initial height of the drop jump) or by increasing the body mass m of the athlete (adding a weighted vest). The purpose of this study was to investigate the behavior of the forcetime parameters of the force impulse by varying the kinematic impulse, using unloaded and loaded drop jumping. METHOD Ten top track & field and diving athletes (6 male and 4 female) participated in this study, 17-24 years old. The subjects were instructed to perform three unloaded drop jumps from heights (drop velocities) of 0.30 m (2.43 d s ) , 0.45m (2.97 d s ) , 0.55m (3.28 d s ) and two loaded drop jumps from a standard height of 0.30m (2.434s) where the additional load was defined based on the Kinematic impulses that arise from the unloaded drop jumps the height of 0.45m and 0.55111 respectively. A Kistler fore platform was used to record the force-time curves of the jumps. RESULTS AND DISCUSSION The calculated values of the average vertical jumped distances for the unloaded conditions (drop height 0.45m,0.55m), as it was expected, were found to be 20% and 31% higher in comparison to the loaded drop jumps respectively. The results of the analysis of the variability in the force-time parameters have shown no significant differences (p>.05, student's t-test at .05 level) for the total average force (acceleration force and loaded force) between unloaded and loaded jumps while for the acceleration force significant differences (

The Hellenic type of nondeletional hereditary persistence of fetal hemoglobin results from a novel mutation (g.-109G>T) in the HBG2 gene promoter

Nondeletional hereditary persistence of fetal hemoglobin (nd-HPFH), a rare hereditary condition resulting in elevated levels of fetal hemoglobin (Hb F) in adults, is associated with promoter mutations in the human fetal globin (HBG1 and HBG2) genes. In this paper, we report a novel type of nd-HPFH due to a HBG2 gene promoter mutation (HBG2:g.-109G>T). This mutation, located at the 3′ end of the HBG2 distal CCAAT box, was initially identified in an adult female subject of Central Greek origin and results in elevated Hb F levels (4.1%) and significantly increased Gγ-globin chain production (79.2%). Family studies and DNA analysis revealed that the HBG2:g.-109G>T mutation is also found in the family members in compound heterozygosity with the HBG2:g.-158C>T single nucleotide polymorphism or the silent HBB:g.-101C>T β-thalassemia mutation, resulting in the latter case in significantly elevated Hb F levels (14.3%). Electrophoretic mobility shift analysis revealed that the HBG2:g.-109G>T mutation abolishes a transcription factor binding site, consistent with previous observations using DNA footprinting analysis, suggesting that guanine at position HBG2/1:g.-109 is critical for NF-E3 binding. These data suggest that the HBG2:g-109G>T mutation has a functional role in increasing HBG2 transcription and is responsible for the HPFH phenotype observed in our index cases

Scaling Properties of Meteorological Time Series Using Detrended Fluctuation Analysis

Meteorological parameters depend on a diversity of natural processes and show random fluctuations on different temporal and spatial scales as a result of the relevant complex natural processes. A powerful tool for examining these fluctuations is the Detrended Fluctuation Analysis (DFA), which detects long-term correlations in nonstationary time series. In this study, we apply the DFA method to daily meteorological time series (i.e. temperature, pressure, relative humidity and wind speed) for the Thessaloniki surface weather station from January 1973 to December 2014. By examining long-range correlations, we detect if the time series exhibit long and/or short range “memory”. Moreover, we compare the behavior of these time series from the aspect of DFA, focusing on the observed similarities or differences of the relevant findings

Distribution of air temperature multifractal characteristics over Greece

In this study, Multifractal Detrended Fluctuation Analysis (MF-DFA) is applied to daily temperature time series (mean, maximum and minimum values) from 22 Greek meteorological stations with the purpose of examining firstly their scaling behavior and then checking if there are any differences in their multifractal characteristics. The results showed that the behavior is the same at almost all stations, i.e., time series are positive long-term correlated and their multifractal structure is insensitive to local fluctuations with large magnitude. Moreover, this study deals with the spatial distribution of the main characteristics of multifractal (singularity) spectrum: the dominant Hurst exponent, the width of the spectrum, the asymmetry and the truncation type of the spectrum. The spatial distributions are discussed in terms of possible effects from various climatic features. In general, local atmospheric circulation and weather conditions are found to affect the shape of the spectrum and the corresponding spatial distributions. Furthermore, the intercorrelation of the main multifractal spectrum parameters resulted in a well-defined group of stations sharing similar multifractal characteristics. The results indicate the usefulness of the non-linear analysis in climate research due to the complex interactions among the natural processes. © 2018 by the authors

Multifractal scaling properties of daily air temperature time series

The aim of the current research study is to examine the scaling properties of the mean daily, maximum and minimum air temperature time series of a single coastal site, located at the island of Crete in Greece. The Multifractal Detrended Fluctuation Analysis (MF-DFA) is used to examine the time series long-term correlation and the singularity spectrum to estimate the multifractality degree. The analysis reveals that the daily temperature time series exhibit a multifractal behavior, are positive long-term correlated and that their multifractal structure is insensitive to local fluctuations with large magnitudes. © 2017 Elsevier Lt

Multifractal Detrended Fluctuation Analysis of temperature reanalysis data over Greece

The Multifractal Detrended Fluctuation Analysis (MF-DFA) is used to examine the scaling behavior and the multifractal characteristics of the mean daily temperature time series of the ERA-Interim reanalysis data for a domain centered over Greece. The results showed that the time series from all grid points exhibit the same behavior: they have a positive long-term correlation and their multifractal structure is insensitive to local fluctuations with a large magnitude. Special emphasis was given to the spatial distribution of the main characteristics of the multifractal spectrum: the value of the Hölder exponent, the spectral width, the asymmetry, and the truncation type of the spectra. The most interesting finding is that the spatial distribution of almost all spectral parameters is decisively determined by the land-sea distribution. The results could be useful in climate research for examining the reproducibility of the nonlinear dynamics of reanalysis datasets and model outputs. © 2019 by the authors

Turbulence Models Studying the Airflow around a Greenhouse Based in a Wind Tunnel and Under Different Conditions

Turbulence phenomena created around a greenhouse due to different wind loads are key factors in its structural design and significantly affect the ventilation rates through its side and roof openings. Using the turbulence models of ANSYS FLUENT software to investigate the airflow around an arched-roof-greenhouse-shaped obstacle placed inside a wind tunnel was the aim of this study. Velocity and pressure areas around the obstacle were examined by selecting three different turbulence models (Standard, RNG and Realizable k–ε models) under three different airflow entry velocities (0.34, 1.00 and 10.00 m s−1) in the wind tunnel. All k–ε models showed that when the air velocity was intensified, the airflow was identified as turbulent. The horizontal velocity profile predicted more accurately the presence of vortices in contrast with the vector sum of the perpendicular velocity components. Vortices were formed upstream, above the roof and downstream of the obstacle, and the applied models showed that when airflow velocity increases, the size of the upstream vortex decreases. Finally, there was a strong indication from the modeling results that the vortex on the roof of the obstacle was an extension of the vortex that was created downstream