Persistence Homology Of Entangled Rings

Topological constraints (TCs) between polymers determine the behaviour of complex fluids such as creams, oils and plastics. Most of the polymer solutions used every day life employ linear chains; their behaviour is accurately captured by the reptation and tube theories which connect microscopic TCs to macroscopic viscoelasticity. On the other hand, polymers with non-trivial topology, such as rings, hold great promise for new technology but pose a challenging problem as they do not obey standard theories; additionally, topological invariance -- i.e. the fact that rings must remain unknotted and unlinked if prepared so -- precludes any serious analytical treatment. Here we propose an unambiguous, parameter-free algorithm to characterise TCs in polymeric solutions and show its power in characterising TCs of entnagled rings. We analyse large-scale molecular dynamics (MD) simulations via persistent homology, a key mathematical tool to extract robust topological information from large datasets. This method allows us to identify ring-specific TCs which we call "homological threadings" (H-threadings) and to connect them to the polymers' behaviour. It also allows us to identify, in a physically appealing and unambiguous way, scale-dependent loops which have eluded precise quantification so far. We discover that while threaded neighbours slowly grow with the rings' length, the ensuing TCs are extensive also in the asymptotic limit. Our proposed method is not restricted to ring polymers and can find broader applications for the study of TCs in generic polymeric materials.Comment: Accepted for publication in Physical Review Research. 10 pages, 4 figures in main text + 2 figures in appendi

Intra-Session Reliability of Sprint Performance on a Non-Motorised Treadmill for Healthy Active Males and Females

This study examined the intra-session reliability of sprint performance on a non-motorized treadmill amongst healthy, active male and female adults. One hundred and twenty participants (males n = 77; females n = 45) completed two familiarization sessions, followed by a third session that consisted of three trials (T1, T2, T3) of maximal sprints (4-s), interspersed by three minutes of recovery. Combining males and females exhibited moderate-to-excellent test-retest reliability (intra-class correlation coefficient, ICC), minimal measurement error (coefficient of variation, CV) and trivial differences between trials (effect size, ES) for speed, power, total work and acceleration (ICC = 0.82–0.98, CV = 1.31–8.45%, ES = 0.01–0.22). The measurement error was improved between comparisons of T1 vs. T2 (CV = 1.62–8.45%, ES = 0.12–0.22) to T2 vs. T3 (CV = 1.31–6.56%, ES = 0.01–0.07) and better for females (CV = 1.26–7.94%, ES = 0.001–0.26) than males (CV = 1.33–8.53%, ES = 0.06–0.31). The current study demonstrated moderate-to-excellent reliability and good-moderate measurement error during a 4-s sprint on a non-motorized treadmill. However, sex had a substantial impact with females exhibiting better values. Practitioners should employ at least two separate trials within a session, in addition to multiple familiarization sessions, to achieve reliable non-motorized treadmill sprint performances

Possível envolvimento de atividade do proteassoma na germinação induzida por etileno em embriões dormentes de girassol

Freshly harvested sunflower seeds (Helianthus annuus L., Asteraceae) present physiological dormancy localized at the embrionary axis which prevents germination at low temperatures. However, dormant embryos reach about 100 % germination when incubated with the phytohormone ethylene during imbibition. To examine whether proteinase activities are implicated in the breaking of dormancy by ethylene, dormant embryos were treated with the proteinase inhibitors leupeptin, E64 and the proteasome specific inhibitor clasto-lactacystin ß-lactone (lactacystin). A few embryos (< 10 %) germinated at 10 oC in absence of ethylene but ethylene-treated embryos reached high germinability (~90 %) in the presence of leupeptin, E64, water and DMSO. On the other hand, incubation in lactacystin strongly reduced (< 20 %) the ethylene-induced germination in a dose-dependent manner. Lactacystin did not affect the germinability at 25 oC (temperature in which the embryos are no longer dormant) but increased the average germination time. The results suggest that proteasome activity may be involved in the removal of dormancy by ethylene and in the progression of the germination of sunflower embryos. _________________________________________________________________________________ ABSTRACTSementes recém-colhidas de girassol (Helianthus annuus L., Asteraceae) apresentam dormência fisiológica localizada no eixo embrionário, bloqueando a germinação em baixas temperaturas. Contudo, os embriões dormentes apresentam germinabilidade próxima a 100 % quando incubados na presença de etileno durante a embebição. Para verificar se determinadas proteinases estão envolvidas na quebra da dormência pelo etileno, embriões dormentes de girassol foram tratados com os inibidores de proteinases leupeptina e E64 e o inibidor específico do proteasoma lactacistina (clasto-lactacystin ß-lactone). Observou-se que embriões incubados a 10 oC na ausência de etileno apresentaram germinabilidade menor que 10 % em todos os inibidores testados. Embriões incubados a 10 oC na presença de etileno apresentaram alta germinabilidade (~90 %) nos tratamentos com leupeptina, E64, água e DMSO, contudo, no tratamento com lactacistina a germinabilidade foi reduzida significativamente (< 20 %) numa relação concentraçãodependente. Incubação dos embriões a 25 oC, temperatura na qual a germinação ocorre sem necessidade de etileno, a lactacistina não afetou a germinabilidade (> 90 %), mas aumentou significativamente o tempo médio de germinação. Os resultados sugerem que a atividade do proteasoma pode estar envolvida tanto na quebra da dormência por etileno como na progressão da germinação de embriões de girassol

Differences in physical performance according to the competitive level in futsal players

The purpose of the present study was to describe performance in acceleration capacity, change of direction ability, vertical jump, horizontal jump, repeated sprint ability, and endurance (Yo-Yo Intermittent Recovery Test Level 1) in futsal players, and analyze the differences according to competitive categories or levels. The total sample (n = 40) was divided into three groups depending on the category in which the participants competed: Second Division B (n = 15), Third Division (n = 12) and juniors (n = 13). All the tests were performed with participants' regular competition shoes and on the usual playing surface, in an indoor pavilion with a floating wood floor. The results of the study did not show significant differences in acceleration capacity (5 and 15 m) or change of direction ability among the different categories. In contrast, significant differences were found among the categories with regard to horizontal jump and vertical jump capacity (p 0.05). The distance covered in the YoYo Intermittent Recovery Test Level 1 by the Second Division B and the Third Division groups was greater than that covered by the junior group. In the light of these results repeated sprint ability and aerobic endurance could be two discriminating qualities of the competitive level among different futsal categories

Influence of warm-up duration on perceived exertion and subsequent physical performance of soccer players

© 2019 Institute of Sport. All rights reserved. The aim of this study was to analyse the effects of three warm-up protocols with different durations in semi-professional soccer players. Fifteen semi-professional soccer players performed three warmup protocols (Wup₂₅ₘᵢₙ: 25 min, Wup₁₅ₘᵢₙ: 15 min and Wup₈ₘᵢₙ: 8 min duration) on three different days. Before (pre-test) and after (post-test) each warm-up protocol, the players’ physical performance (sprint, vertical jump and change of direction) was evaluated and all the players were asked to respond to the subjective scale of readiness to play a match. Also, after completing each warm-up protocol, all players responded to the rating of perceived exertion (RPE) scale. Although all protocols significantly improved the feeling of players being prepared to play the game (p<0.05 or p<0.01), after performing the Wup₂₅ₘᵢₙ protocol the players performed worse in the 10 m sprint (p<0.01) and in the 20 m sprint (p<0.05). However, the Wup₈ₘᵢₙ protocol significantly improved performance in both the 10 m sprint (p<0.05) and the 20 m sprint (p<0.05). In addition, with the Wup₂₅ₘᵢₙ protocol players stated a higher perceived exertion (RPE) (p < 0.05) than in the Wup₁₅ₘᵢₙ and Wup₈ₘᵢₙ protocols. The Wup₈ₘᵢₙ protocol was the only one that improved the acceleration ability of the soccer players in this study

Charge Oscillations in Superconducting Nanodevices Coupled to External Environments

Charge oscillations in certain nanodevices, more specifically the so-called Superconducting Cooper Pair Boxes (SCB), are usually interpreted as an effect of macroscopic quantum coherence; an alternative explanation is however possible in terms of the Gross-Pitaewski equation for the classical order parameter. These two explanations are based on different quantum states assigned to the SCB, occupation number states in the first case, coherent-like states in the second one. We show that, when the SCB is weakly coupled to an external source of noise and dissipation, occupation number states are much more unstable than coherent ones.Comment: 8 pages, LaTe

ANALYSIS OF THE SPRINTS FEATURES DURING FUTSAL MATCHES

The purpose of this study was to analyse the repeated-sprint sequences (RSS) and to characterise the sprints performed during futsal matches. Automatic tracking system was used to obtain the player’s trajectories (n=97) during five official matches. The sprints were analysed during the both halves and RSS were categorised according to the number of sprints and the time between them. The results showed a decrease in the number of sprints per minute in the second half. However, the duration of the sprints was greater in the second half. For the RSS analysis, the results showed that the most frequent RSS consisted of two sprints interspersed with a maximum of 15 s of recovery. The study characterised the features of sprinting of futsal players, which can help coaches to plan physical training and assessments according to the sport requirements

Comparison of Heart Rate Variability Before and After a Table Tennis Match

The aim of this study was to compare heart rate variability indices before and after a table tennis match. Sixteen males (21.86 +/- 8.34 yr, 1.73 +/- 0.08 m, 64.09 +/- 13.39 kg and 21.46 +/- 4.38 kg.m(-2)) were evaluated in 21 matches, before and after the match. We observed that in time domain analysis, Mean RR, SDNN, LnRMSSD and pNN50 after match values were significantly lower than before match values (p 0.05) in STD HR. Meanwhile, frequency domain analysis showed LF Power (log), HF Power (log) and HF Power (in normalized units) after match values significantly lower than before match values (p 0.05) in LF Power (ms(2)), LF Power (in normalized units) and HF Power (ms(2)) values. Non-linear analysis showed SD1 and SD2 POST values significantly lower than PRE values (p < 0.05), while no significant differences were observed in SD2/SD1 value between POST and PRE analysis. As conclusion, due to the physiological strain of the table tennis match, changes were observed in heart rate variability values, suggesting an increase of sympathetic influence and a reduction of the parasympathetic influenceThe authors would like to thank table tennis players from the Gasteiz, Leka Enea and Gailak Table Tennis Clubs and the collaboration of their Presidents. The authors gratefully acknowledge the support of a Spanish government subproject Mixed method approach on performance analysis (in training and competition) in elite and academy sport [PGC2018-098742-B-C33] (2019-2021) [of the Ministry of Science, Innovation and Universities (MCIU), the State Research Agency (AEI) and the European Regional Development Fund (EDRF)], that is part of the coordinated project New approach of research in physical activity and sport from mixed methods perspective (NARPAS_MM) [SPGC201800X098742CV0

Can off-training physical behaviors influence recovery in athletes? A sccoping review

Recently, the attention on recovery in sport increased enormously although there is lack of scientific evidence on the role of lifestyle in terms of movement [i.e., physical behaviors (PBs)], apart from sleep. Few studies assessed physical activity (PA) and sedentary behavior (SB) in athletes. The aims of this scoping review were to answer to the following scientific questions: (1) How active/inactive are competitive athletes out of training? (2) Do off-training PBs affect recovery, performance, and health? (3) What strategies can be implemented to improve recovery using off-training PBs, apart from sleep? From 1,116 potentially relevant articles, nine were eligible for inclusion in this review. The main issues identified were related to the heterogeneity concerning the types of sports, age category, gender, competitive level, sample size, and instruments/devices adopted, the paucity of studies investigating the effects of PBs while awake on recovery, and the lack of experimental designs manipulating PBs while awake to accelerate recovery. Furthermore, PA and SB domains were rarely investigated, while no research articles focused on the combined effect of 24-h PBs. Eight out of nine studies measured PA, seven SB, and two included sleep. Three studies included training practice into PA measurement by the means of accelerometry. Overall, almost the totality of the athletes achieved recommended PA levels although they sustained prolonged SB. In conclusion, more descriptive researches are needed in different athletic populations and settings. Furthermore, experimental designs aimed at investigating the effects of PBs manipulation on recovery and the putative mechanisms are encouraged

Aerobic Fitness Evaluation during Walking Tests Identifies the Maximal Lactate Steady State

Objective. The aim of this study was to verify the possibility of lactate minimum (LM) determination during a walking test and the validity of such LM protocol on predicting the maximal lactate steady-state (MLSS) intensity. Design. Eleven healthy subjects (24.2 ± 4.5 yr; 74.3 ± 7.7 kg; 176.9 ± 4.1 cm) performed LM tests on a treadmill, consisting of walking at 5.5 km · h−1 and with 20–22% of inclination until voluntary exhaustion to induce metabolic acidosis. After 7 minutes of recovery the participants performed an incremental test starting at 7% incline with increments of 2% at each 3 minutes until exhaustion. A polynomial modeling approach (LMp) and a visual inspection (LMv) were used to identify the LM as the exercise intensity associated to the lowest [bLac] during the test. Participants also underwent to 2–4 constant intensity tests of 30 minutes to determine the MLSS intensity. Results. There were no differences among LMv (12.6 ± 1.7%), LMp (13.1 ± 1.5%), and MLSS (13.6 ± 2.1%) and the Bland and Altman plots evidenced acceptable agreement between them. Conclusion. It was possible to identify the LM during walking tests with intensity imposed by treadmill inclination, and it seemed to be valid on identifying the exercise intensity associated to the MLSS