Browsing by Author "Martins, Francisco"
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- Bisimulations in SSCCPublication . Filipe, Luís Cruz; Lanese, Ivan; Martins, Francisco; Ravara, António; Vasconcelos, Vasco T.This report studies different definitions of bisimulation within the Stream-Based Service-Centered Calculus (SSCC) and shows that both strong and weak ground bisimulation are non-input congruences
- Body composition variations between injured and non-injured professional soccer playersPublication . Martins, Francisco; França, Cíntia; Henriques, Ricardo; Ihle, Andreas; Przednowek, Krzysztof; Marques, Adilson; Lopes, Hélder; Sarmento, Hugo; Gouveia, ElvioProfessional soccer is characterized by its physical demands, making players' exposure to high injury risks a growing problem. It is crucial to study the factors associated with injuries in professional soccer. This study aimed to investigate the relationship between age, body composition, and others variables related with the injury profile of professional soccer players of a specific Portuguese team. Also, it analyzed the impact of the injury profile on soccer's variations in body fat (BF%), skeletal muscle mass (SMM) and total body water (TBW) throughout the season. The sample comprised 31 male professional soccer players competing in the First Portuguese Soccer League. Older players had a higher prevalence of muscular injuries. Midfielders and forwards showed the highest number of muscular injuries during the season being quadriceps the most affected zone. Considering players' BF% [Wilks' Lambda = 0.42, F (7, 23) = 4.61, p = 0.002, r = 0.58], SMM [Wilks' Lambda = 0.59, F (6, 23) = 2.70, p = 0.039, r = 0.41] and TBW [Wilks' Lambda = 0.54, F (7, 23) = 2.80, p = 0.029, r = 0.46] there was a substantial main effect for the assessments performed throughout the season and the injury status. Age assumes relevance in explaining the injury profile. The impact of the injury profile on soccer's variations in BF%, SMM and TBW throughout the season must be analyzed considering the clinical relevance.
- Changes in estimated body composition and physical fitness of adolescent boys after one year of soccer trainingPublication . França, Cíntia; Martinho, Diogo V.; Gouveia, Elvio; Martins, Francisco; Marques, Adilson; Ribeiro, Tiago D.; Nascimento, Marcelo de Maio; Lopes, Helder; Rodrigues, Ana; Ihle, AndreasSports participation is one of the most popular forms of physical activity among youngsters. This study aimed to examine the changes in the estimated body composition, strength, and flexibility of adolescent boys after 12 months of soccer training compared with those of age-matched controls with non-sports participation. We assessed 137 boys (62 soccer players and 75 controls) at baseline (TM1) and 12 months later (TM2). The differences in estimated body composition, strength, and flexibility were investigated using a repeated measure analysis of variance. The analysis revealed a significant main effect of soccer training on fat mass (F = 73.503, p ≤ 0.01, η2 = 0.59) and fat-free mass (F = 39.123, p ≤ 0.01, η2 = 0.48). Over time, the soccer group decreased their fat mass and increased their fat-free mass, while the opposite results were observed for the controls. Among physical fitness tests, a substantial effect of soccer training was evidenced for the sit-up performance (F = 16.224, p ≤ 0.01, η2 = 0.32). Regarding the time factor, significant effects were noted for height and handgrip strength. No significant differences were detected for flexibility. Overall, the benefits of soccer training were exhibited by the larger improvements in fat mass, fat-free mass, sit-ups, and handgrip strength performance, underlining the important role of soccer participation during adolescence.
- Compiling the $\pi$-calculus into a Multithreaded Typed Assembly LanguagePublication . Cogumbreiro, Tiago; Martins, Francisco; Vasconcelos, Vasco T.Current trends in hardware made available multi-core CPU systems to ordinary users, challenging researchers to devise new techniques to bring software into the multi-core world. However, shaping software for multi-cores is more envolving than simply balancing workload among cores. In a near future (in less than a decade) Intel prepares to manufacture and ship 80-core processors; programmers must perform a paradigm shift from sequential to concurrent programming and produce software adapted for multi-core platforms. In the last decade, proposals have been made to compile formal concurrent and functional languages, notably the $\pi$-calculus, typed concurrent objects, and the $\lambda$-calculus, into assembly languages. The last work goes a step further and presents a series of type-preserving compilation steps leading from System F to a typed assembly language. Nevertheless, all theses works are targeted at sequential architectures. This paper proposes a type-preserving translation from the $\pi$-calculus into MIL, a multithreaded typed assembly language for multi-core/multi-processor architectures. We start from a simple asynchronous typed version of the $\pi$-calculus and translate it into MIL code that is then linked to a run-time library (written in MIL) that provides support for implementation of the $\pi$-calculus primitives (e.g., queuing messages and processes). In short, we implement a message-passing paradigm in a shared memory architecture
- Controlling Security Policies in a Distributed EnvironmentPublication . Martins, Francisco; Vasconcelos, Vasco Manuel Thudichum de SerpaThis thesis proposes a typing discipline to control the migration of code in a distributed, mobile environment. Our approach is to express security policies as types, to characterise security faults as typing errors, and to use a type system to statically enforce a given security policy. We prove a type safety result that ensures that well-typed programs do not violate the prescribed security policy. We start by analysing a simple, yet non-trivial, approach to control the access to resources in a concurrent language (the $\pi-$calculus). In the concurrent framework we study the control of actions at program level and, in a finer-grained scenario, at resource level. Moving into a distributed, concurrent platform (using the D$\pi$-calculus as the underlying language), we analyse the impact of code mobility in the verification of security. In a first stage, we control mobility by specifying security policies at site level, and by considering only the source site, the target site, and the action to be executed, as the relevant information to decide if an action should be performed. This approach revealed some vulnerabilities, namely that a site cannot control by itself its own security: it always need to trust in third-parties. Aiming at overcoming this undesired lacuna, as well as simplifying the writing and maintenance of security policies, we introduce the concepts of groups, a cluster of sites that share the same security polices, and of path to account for the sequence of sites visited by migrating code. We define security at group level, avoiding the replication of polices by the sites that are members of the same group. Granting privileges to migrating paths allows for a site to precisely select the action that it grants permission to be executed (without needing to depend on third-parties). Our major result is that, recalling Milners motto, well-typed programs do not go wrong, in the sense that, if a network has no typing error, then it does not incur in a security fault.
- Controlling Security Policies in a Distributed EnvironmentPublication . Martins, Francisco; Vasconcelos, Vasco T.This paper presents a type system to control the migration of code between nodes in a concurrent distributed framework, using Dpi. We express resource policies with types and enforce them via a type system. Sites are organised hierarchically in subnetworks that share the same security policies, statically specified by a network administrator. The type system guarantees that, at runtime, there are no security policies violations
- Differential patterns in motivations for practicing sport and their effects on physical activity engagement across the lifespanPublication . de Maio Nascimento, Marcelo; Gouveia, Elvio; Gouveia, Bruna; Marques, Adilson; França, Cíntia; Campos, Pedro; Martins, Francisco; García-Mayor, Jesús; Ihle, AndreasThis study aims to report what motivates individuals to be physically active, to determine whether motivating factors influence physical activity (PA) levels, and whether this differs across the lifespan. This is a cross-sectional study with 498 individuals: 117 adolescents, 306 adults, and 75 older adults. PA was assessed using Baecke's questionnaire, and motivating factors for practicing sports were investigated using a scale with twelve questions. The factor analysis identified three motivating factors for sports practice: psychosocial, bodily, and well-being. The scale's overall reliability and internal consistency indicated a Cronbach's alpha of 0.885. The analysis of covariance (ANCOVA) adjusted for sex indicated the three factors as having a significant effect on PA (p < 0.050); however, only the well-being factor showed a significant interaction with age groups (p = 0.023, ηp2 = 0.030). Subsequently, the effect of the well-being factor on PA scores in each age group was explored through regression analyses. Only older adults showed a significant association in the unadjusted [OR = 0.378, p = 0.001, R2 = 0.243] and the sex-adjusted analysis [OR = 0.377, p = 0.001, R2 = 0.288]. These results help us to better understand the underlying motivational reasons in different age groups for engaging in sports.
- Disciplining Orchestration and Conversation in Service-Oriented ComputingPublication . Lanese, Ivan; Vasconcelos, Vasco T.; Martins, Francisco; Ravara, AntónioWe give a formal account of a calculus for modeling service-based systems, suitable to describe both service composition (orchestration) and the protocol that services run when invoked (conversation). The calculus includes primitives for defining and for invoking services, for isolating conversations between requesters and providers of services, and primitives for orchestrating services, that is, to make use of existent services as building blocks to accomplish complex tasks. The calculus is equipped with a reduction and a labeled transition semantics; an equivalence result relates the two. To give an hint on how the structuring mechanisms of the language can be exploited for static analysis we present a simple type system guaranteeing the compatibility between the protocols for service definition and for service invocation, and ensuring the sequentiality of each protocol
- Four-year associations of wish-to-die trajectories with changes in the frailty of European citizens aged 50 and overPublication . de Maio Nascimento, Marcelo; Marques, Adilson; Ferrari, Gerson; Martins, Francisco; França, Cíntia; Gouveia, Elvio; Ihle, AndreasBackground: A death wish is a passive ideation about thoughts that suggest dying is better than continuing to live. We investigated the associations of different wish-to-die (WTD) trajectories with changes in frailty over a four-year period in European citizens aged 50 and over. Methods: A longitudinal analysis was conducted with 27,350 participants (13,921 women) from 17 European countries, all aged ≥50 years, who responded to waves 6 and 8 of the Survey of Health, Ageing, and Retirement in Europe (SHARE) project. WTD was assessed by asking, 'In the last month, have you felt that you would rather be dead?'. Frailty was measured using the SHARE-Frailty (SHARE-FI) questionnaire. Results: A significant effect of time on frailty was observed, with a medium effect size (p < 0.001, ηp2 = 0.08), as well as a significant time × group interaction with a medium effect size (p < 0.001, ηp2 = 0.12). Post hoc analysis revealed a 54.5 % increase in frailty for the continued non-WTD trajectory group over four years. The non-WTD to WTD trajectory group showed a 186.0 % increase in frailty, while the continued WTD group showed a 27.9 % increase in frailty. On the other hand, the group with a trajectory from WTD to non-WTD indicated a reduction in the index of 28.8 %. Conclusions: Emerging WTD may be associated with increased frailty in older age. Conversely, frailty may be reduced among those who exchanged the passive idealization of dying for living.
- Lower body strength and body composition in female footballPublication . França, Cíntia; Saldanha, Carolina; Martins, Francisco; de Maio Nascimento, Marcelo; Marques, Adilson; Ihle, Andreas; Sarmento, Hugo; Campos, Pedro; Gouveia, ElvioLower-body strength plays a crucial role in football performance and injury prevention, and thus, monitoring of strength variables has become crucial in the training process. This study aims to (1) assess knee muscle strength performance through intra- and inter-limb asymmetries and (2) examine the relationships between knee muscle strength, body composition, and vertical jump performance (squat jump and countermovement jump). Twenty-seven semiprofessional female football players (21.5 ± 4.9 years) were evaluated for body composition, isokinetic knee muscle strength (60º/s and 180º/s), and vertical jump tasks. Peak torque (PT), peak torque/body weight (PT/BW), bilateral strength deficit, and the hamstring-to-quadriceps strength ratio (H/Q) for knee extensors (KE) and flexors (KF) in both the preferred and non-preferred legs. The H/Q ratio and the bilateral strength deficit revealed no significant intra- or inter-limb asymmetries in knee muscle strength. Strong correlations were found between vertical jump performance and KE strength at both 60º/s (p ≤ 0.01) and 180º/s (p ≤ 0.01). Additionally, a significant negative correlation was observed between vertical jump performance and body fat percentage (p ≤ 0.01). These findings highlight the critical role of knee muscle strength in explosive tasks and underline the negative impact of higher body fat on lower-body strength performance.