Search results for "Explosive"
showing 10 items of 123 documents
Hypovitaminosis D in Young Basketball Players: Association with Jumping and Hopping Performance Considering Gender
2021
This study aimed to verify whether a group of young well-trained basketball players presented deficiencies in vitamin D concentration, and to analyze whether there was an association between vitamin D concentration and jumping and hopping performance. Gender differences were considered. Twenty-seven players from an international high-level basketball club (14 female, 16.00 ± 0.55 years
Reliability of measurements during countermovement jump assessments: Analysis of performance across subphases
2020
The aim of this study was to examine the reliability of performance measures in the different phases and sub-phases of the countermovement jump (CMJ). Seventeen male athletes competing at a regional level completed 204 valid trails consisting of the execution of maximal hands-on-waist CMJs performed on a force platform. The vertical ground reaction force (VGRF) data obtained at a sampling frequency of 1000 Hz were used to calculate performance-derived variables and determine key points and jump sub-phases. The relative reliability of 92 variables was assessed using the intraclass correlation coefficient (ICC) from a two-way mixed effects model analyzing the time, force, power, velocity, and…
Acute neuromuscular and endocrine responses and recovery to single session combined endurance and strength loadings: ‘Order effect’ in untrained youn…
2013
The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using two loading orders. Forty-two men were demographically matched to perform a single session of combined endurance+strength (E+S) or strength+endurance (S+E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength and hypertrophic loads with an overall duration of 30 minutes. The endurance loading was conducted on a bike ergometer and performed by continuous cycling over 30min at 65% of subject’s individual maximal Watts. Both loading conditions led to significant acute reducti…
The effects of a 10-week combined maximal and explosive strength and high-intesity endurance training period on neuromuscular performance and 3K time…
2015
Combined strength and endurance training has been noted to produce significant improvements in strength and endurance performances in both men and women. However, there seems to be moderate inhibitory effect regarding strength adaptations, especially considering power production. This study was conducted to investigate the effects of a 10-week combined maximal and explosive strength and high-intensity endurance training period on neuromuscular performance and 3K time-trial in males and females. A total of 19 healthy recreationally trained subjects (Males: M= 10, Females: F= 9) completed a 10-week combined strength and endurance training period. All subjects trained twice a week strength and…
External sustainability in Spanish economy: bubbles and crises, 1970–2020
2023
We address the issue of the sustainability Spain’s exter-nal debt, using data for the period 1970–2020. To detect episodes of potentially explosive behavior of the Spanish net foreign assets over GDP ratio and the current account balance over GDP ratio, as well as episodes of external adjustments over this long period, we employ a recursive unit root test approach. Our empirical analysis leads us to conclude that there is some evidence of bubbles in the ratio between Spanish net foreign assets and the GDP. In contrast, the evidence that the ratio between the Spanish current account balance and the GDP had explosive subperiods is very weak. The episode of explosive behavior identified in the…
Petrology and geochemistry of peri-Mediterranean carbonatite magmatism: case studies from Fuerteventura (Canary Islands) and Mt. Vulture volcano (sou…
2023
Carbonatites are rare magmatic rocks of great scientific and economic importance, and carbonatite magmatism is mainly associated with intraplate continental tectonic settings, with some rare occurrences in oceanic contexts. Despite their importance, many aspects of carbonatite petrogenesis and evolution processes remain still poorly constrained. In order to further constrain the mantle source and the storage system of carbonatite magmas, Fuerteventura (Canary Islands) was taken as a representative case study of oceanic carbonatites, while Mt. Vulture (southern Italy) was taken as a representative case study of intra-continental carbonatites, with a two-fold aim: to understand (i) the role o…
Geochemistry and volatile content of magmas feeding explosive eruptions at Telica volcano (Nicaragua)
2017
Telica volcano, in north-west Nicaragua, is a young stratovolcano of intermediate magma composition producing frequent Vulcanian to phreatic explosive eruptions. The Telica stratigraphic record also includes examples of (pre)historic sub-Plinian activity. To refine our knowledge of this very active volcano, weanalyzedmajor element composition and volatile content of melt inclusions fromsomestratigraphically significant Telica tephra deposits. These include: (1) the Scoria Telica Superior (STS) deposit (2000 to 200 years Before Present; Volcanic Explosive Index, VEI, of 2–3) and (2) pyroclasts from the post-1970s eruptive cycle (1982; 2011). Based on measurements with nanoscale secondary ion…
Modern Multispectral Sensors Help Track Explosive Eruptions
2013
Due to its massive air traffic impact, the 2010 eruption of Eyjafjallajokull was felt by millions of people and cost airlines more than U.S. $1.7 billion. The event has, thus, become widely cited in renewed efforts to improve real-time tracking of volcanic plumes, as witnessed by special sections published last year in Journal of Geophysical Research, (117, issues D20 and B9).
Phase petrology reveals shallow magma storage prior to large explosive silicic eruptions at Hekla volcano, Iceland
2017
Abstract Understanding the conditions that culminate in explosive eruptions of silicic magma is of great importance for volcanic hazard assessment and crisis mitigation. However, geological records of active volcanoes typically show a wide range of eruptive behavior and magnitude, which can vary dramatically for individual eruptive centers. In order to evaluate possible future scenarios of eruption precursors, magmatic system variables for different eruption types need to be constrained. Here we use petrological experiments and microanalysis of crystals to clarify the P – T – x state under which rhyodacitic melts accumulated prior to the H3 eruption; the largest Holocene Plinian eruption of…
H2O-content and temperature limit the explosive potential of rhyolite magma during Plinian eruptions
2019
Abstract Recent rhyolite eruptions on Earth have demonstrated their capacity to produce a multitude of hazards, including ash formation lasting months and impacting the large reaches of the southern hemisphere. Nevertheless, the underlying mechanisms driving these eruptions are not yet fully understood. Magmatic volatiles, especially H2O, dictate whether volcanic eruptions proceed explosively or effusively. Experimental evidence for the role played by H2O in driving explosive fragmentation is rare, in particular in the eruption of rhyolitic magma. Here we show that when hydrous rhyolitic obsidians from Chaiten Volcano (Chile) are experimentally heated above their glass transition temperatur…