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Lower limbs strength variations between injured and non-injured professional soccer players
Publication . Martins, Francisco; França, Cíntia; Hugo Sarmento; Ricardo Henriques; Krzysztof Przednowek; Marcelo de Maio Nascimento; Adilson Marques; Andreas Ihle; Gouveia, Élvio Rúbio; Sarmento, Hugo; Marques, Adilson; Ihle, Andreas; Gouveia, Élvio Rúbio
Due to its physical demands, professional soccer is becoming a real challenge regarding players’ exposure to high injury risk. Given its tight correlation with high-intensity actions, muscular strength is a crucial physical characteristic for soccer players. Therefore, the aims of this study are (a) to compare the vertical jumping performance during the season according to the injury profile, and (b) to investigate differences in isokinetic strength performance at the beginning and the end of the season. Twenty-one male professional soccer players (age: 26.0 ± 4.1 years, height: 181.0 ± 6.9 cm, body mass: 73.7 ± 6.9 kg) were assessed in isokinetic strength (Biodex System 4 Pro Dynamometer), and Optojump Next (Microgate, Bolzano, Italy). Isokinetic strength analyses considered the peak torque scores of knee flexors and knee extensors, according to the player's preferred and non-preferred limb. The countermovement and squat jump maximum height were assessed as lower body explosive strength indicators. No significant differences were found when comparing injured and non-injured players in vertical jump and isokinetic strength assessments. However, significant results were found when comparing both groups’ initial and final evaluation in isokinetic strength assessment, with both groups significantly improving their performance. Our findings indicate that the overall lower body strength performance was not a discriminant factor between injured and non-injury players. Thus, muscular strength assessment performance increased throughout the season independently of the injury profile. Future research needs to integrate other variables related to sports injuries since they seem to result from multifactorial causes.
Numerical and experimental investigation of thermal regimes of thermionic cathodes of arc plasma torches
Publication . Cunha, M. D.; Sargsyan, M. A.; Gadzhiev, M. Kh; Tereshonok, D. V .; Benilov, M. S .; Benilov, Mikhail; Cunha, Mário
The modelling method based on decoupling the simulation of the cathodic part of the arc (the
cathode and the near-cathode non-equilibrium plasma layer) from the simulation of the arc on
the whole has been extended to cathodes of arc plasma torches, consisting of an insert with a
conical tip, made of pure or doped tungsten, and a surrounding water-cooled copper holder. The
method was validated by comparison with the experiment, performed on a 200 A DC arc in
atmospheric-pressure argon. Standard work function of polycrystalline tungsten of 4.54 eV was
used for modelling of pure-tungsten insert and a good agreement with the experiment was found
with respect to both the insert tip shape and the temperature distribution in the tip, recorded in
the stable operation mode. There are no unambiguous data on the work function for arc
cathodes made of doped tungsten, although in situ measurements of the effective work function
of cathodes of high-pressure arc discharges provide useful hints. On the other hand, the
experiments reported in this work show that the tip temperatures of inserts made of tungsten
doped with 1.5% of thorium, or lanthanum, or yttrium, recorded during the stable-mode
operation at the arc current of 200 A, vary in a rather narrow range 3100–3200 K. This suggests
that the work functions of doped tungsten inserts, operated in the stable mode, are close to each
other as well. Indeed, the results of modelling with the same value of the work function of 3 eV
give a reasonably good agreement with the experiment in all three cases.
Compound Poisson processes: potentials, Green measures and random times
Publication . Yuri Kondratiev; José L. da Silva; Luís da Silva, José
In this paper we study the existence of Green measures for Markov processes with a
nonlocal jump generator. The non-singular jump kernel has no second moment and
satisfies a suitable condition on its Fourier transform. We also study the same problem
for certain classes of random time changes Markov processes with jump generator.
Microplastic ingestion and plastic additive detection in pelagic squid and fish: implications for bioindicators and plastic tracers in open oceanic food webs
Publication . Sambolino, Annalisa; Iniguez, Eva; Herrera, Inma; Kaufmann, Manfred ; Dinis, Ana; Cordeiro, Nereida ; Sambolino, Annalisa; Iñiguez Santamaría, Eva; Kaufmann, Manfred; cordeiro, nereida
The ubiquitous presence of microplastics (MPs) in the ocean represents a potential threat to marine organisms, with
poorly understood long-term adverse effects, including exposure to plastic additives. The present study investigated
the ingestion of MPs in two epipelagic fish species (Trachurus picturatus and Scomber colias) and three pelagic squid spe cies (Loligo vulgaris, Ommastrephes caroli and Sthenoteuthis pteropus) from an open oceanic region of the Northeast Atlan tic. Seven phthalate esters (PAEs) were also analysed in the organisms' tissue, and the potential correlation between
PAEs concentrations and ingested MPs was investigated. Seventy-two fish and 20 squid specimens were collected
and analysed. MPs were found in the digestive tract of all species and in the squid species' gills and ink sacs. The highest
occurrence of MPs was in the stomach of S. colias (85 %) and the lowest in the stomach and ink sac of O. caroli and
L. vulgaris (12 %). Most of the particles identified (>90 %) were fibres. Among all the ecological and biological factors
considered (dietary preferences, season, body size, total weight, liver weight, hepatosomatic index and gastrosomatic
index), only gastrosomatic index (GSI) and season were significant predictors of MPs ingestion in fish species, with a
greater likelihood of ingestion in the cold season and in specimens with higher GSI values (i.e. higher feeding inten sity). Four PAEs (DEP, DIBP, BBP, DEHP) were detected in all the species analysed, with average ∑PAEs concentrations ranging between 10.31 and 30.86 ng/g (wet weight). DIBP was positively correlated with ingested MPs, suggesting
this compound might represent a “plastic tracer”. This study looks into the problem of MPs ingestion for pelagic species
in an open oceanic region, highlighting the most suitable bioindicators and providing essential insights into the factors
that may influence ingestion rates. Additionally, the detection of PAEs in all species indicates the need for further re search on the contamination sources, the effects of these chemicals on marine organisms, and the potential risks to
human health through seafood consumption.
Relevance, recovery and recuperation: a prelude to ring withdrawal
Publication . Fermé, Eduardo; Garapa, Marco; Abhaya Nayak; Reis, Maurício D. L.; Reis, Maurício
In this paper, we introduce recuperative withdrawals, belief change operators that satisfy
recuperation, a postulate weaker than recovery, all the AGM postulates for contraction except
recovery and another postulate which is a slightly stronger condition than conjunctive inclusion.
Furthermore, we present a constructive definition for a class of operators —named ring
withdrawals— which are such that the outcome of a ring withdrawal of a belief set 𝐊 by a
sentence 𝛼 is obtained by adding to the set of most plausible models ‖𝐊‖ all the worlds which are
as close to ‖𝐊‖ as its closest ¬𝛼-worlds. Ring withdrawals satisfy the Lindström and Rabinowicz’s
interpolation thesis. We show that the classes of recuperative withdrawals and of ring withdrawals
are identical. Additionally we show that the class of ring withdrawals is not contained in and does
not contain the class of AGM contractions or the class of severe withdrawals. Finally we present
methods for defining an operator of ring withdrawal by means of a severe withdrawal operator
and by means of an AGM contraction operator, and vice-versa.