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Mullen S.P.,University of Illinois at Urbana - Champaign | Silva M.N.,University of Lisbon | Silva M.N.,Lusophone University of Humanities and Technologies | Sardinha L.B.,University of Lisbon | Teixeira P.J.,University of Lisbon
Research Quarterly for Exercise and Sport | Year: 2016

Purpose: This prospective study was designed to evaluate psychometric properties of the Activity Choice Index (ACI), a measure for assessing one's choice to engage in more effortful, physically active behaviors in the course of daily routines over less-demanding, sedentary behaviors, in a sample of overweight women. Method: The sample included 192 overweight women (Mage = 37.6 ± 7 years; Mbody mass index = 31.6 ± 4.1 kg/m2) who were assessed at baseline and 12 months after beginning a weight management intervention. Results: The unidimensional factor structure was confirmed for the 6-item version of the ACI. Group invariance and temporal invariance were also established. Moreover, ACI scores were positively correlated with self-reported physical activity (as measured by the 7-Day Physical Activity Recall), daily pedometer steps, and 3-day average accelerometer counts. Conclusions: This preliminary investigation provides evidence that a relatively brief self-report instrument for assessing lifestyle physical activity choices has strong psychometric characteristics although convergent evidence is limited. The ACI has potential utility for researchers and practitioners aiming to quantify, or track change in, physical activity in everyday, free-living conditions. This early investigation sets the stage for future research to further delineate and strengthen the measurement of the ACI construct. © 2016 SHAPE America.

Berbakov L.,University of Belgrade | Beko M.,Lusophone University of Humanities and Technologies
2014 22nd Telecommunications Forum, TELFOR 2014 - Proceedings of Papers | Year: 2014

Collaborative beamforming is a promising technique for improving energy efficiency of uplink communications in wireless sensor networks. It is based on the fact that, if carrier phases of individual sensor nodes are synchronized precisely enough, sensor nodes can jointly form a beampattern with stable mainlobe. In this paper, we analyze the bit error rate performance of such collaborative transmission. In particular, we consider a decentralized antenna array where sensors are allowed to perform distributed carrier synchronization and collaborative data transmission simultaneously. We evaluate the system performance by using numerical simulations and provide a semianalytical solution for the overall bit error rate as a function of the algorithm's iteration index. © 2014 IEEE.

Berbakov L.,University of Belgrade | Beko M.,Lusophone University of Humanities and Technologies
2015 23rd Telecommunications Forum, TELFOR 2015 | Year: 2015

Collaborative beamforming is a technique that provides transmission ranges beyond those achievable with single transmitter by combining signals from multiple transmitters. In this paper, we propose an algorithm that distributively selects sensor nodes whose signals combine in a quasi-coherent manner at the base station and computes the corresponding power allocation. In particular, we consider a decentralized antenna array where sensors are not allowed to change their carrier phase and instead only change the transmit power. We evaluate the system performance by using numerical simulations and look more into the impact of the number of sensors on the algorithm's performance. © 2015 IEEE.

Gamito P.,Lusophone University of Humanities and Technologies | Oliveira J.,Lusophone University of Humanities and Technologies | Lopes P.,Lusophone University of Humanities and Technologies | Brito R.,Lusophone University of Humanities and Technologies | And 6 more authors.
Journal of Medical Internet Research | Year: 2014

The consequences of alcohol dependence are severe and may range from physical disease to neuropsychological deficits in several cognitive domains. Alcohol abuse has also been related to brain dysfunction specifically in the prefrontal cortex. Conventional neuropsychological interventions (paper-and-pencil cognitive stimulation training) have a positive effect but are time-consuming, costly, and not motivating for patients. Objective: Our goal was to test the cognitive effects of a novel approach to neuropsychological intervention, using mobile technology and serious games, on patients with alcohol dependence. Methods: The trial design consisted of a two-arm study assessing the cognitive outcomes of neuropsychological intervention with mobile serious games (mHealth) versus control (treatment-as-usual with no neuropsychological intervention) in patients undergoing treatment for alcohol dependence syndrome. Sixty-eight patients were recruited from an alcohol-rehab clinic and randomly assigned to the mHealth (n=33) or control condition (n=35). The intervention on the experimental group consisted of a therapist-assisted cognitive stimulation therapy for 4 weeks on a 2-3 days/week basis. Results: Fourteen patients dropped out of the study. The results of the neuropsychological assessments with the remaining 54 patients showed an overall increase (P<.05) of general cognitive abilities, mental flexibility, psychomotor processing speed, and attentional ability in both experimental (n=26) and control groups (n=28). However, there was a more pronounced improvement (P=.01) specifically in frontal lobe functions from baseline (mean 13.89, SE 0.58) to follow-up (mean 15.50, SE 0.46) in the experimental group but not in the control group. Conclusions: The overall increase in general cognitive function for both experimental and control groups supports the beneficial role of existing alcohol treatment protocols aimed at minimizing withdrawal symptoms, but the differential improvements observed in frontal lobe functioning supports the use of mobile serious games for neuropsychological stimulation to overcome executive dysfunction in patients with alcohol dependence. This trial was negative on two neuropsychological/cognitive tests, and positive on one. © Pedro Gamito, Jorge Oliveira, Paulo Lopes, Rodrigo Brito, Diogo Morais, Diana Silva, Ana Silva, Sara Rebelo, Marta Bastos, Alberto Deus.

Reis C.P.,Lusophone University of Humanities and Technologies | Damge C.,University of Lorraine
Methods in Enzymology | Year: 2012

Since its discovery, insulin has been used as highly specific and effective therapeutic protein to treat type 1 diabetes and later was associated to oral antidiabetic agents in the treatment of type 2 diabetes. Generally, insulin is administered parenterally. Although this route is successful, it still has several limitations, such as discomfort, pain, lipodystrophy at the injection sites and peripheral hyperinsulinemia, which may be the cause of side effects and some complications. Thus, alternative routes of administration have been developed, namely, those based on nanotechnologies. Nanoparticles, made of synthetic or natural materials, have been shown to successfully overcome the inherent barriers for insulin stability, degradation, and uptake across the gastrointestinal tract and other mucosal membranes. This review describes some of the many attempts made to develop alternative and more convenient routes for insulin delivery. © 2012 Elsevier Inc. All rights reserved.

Bastos N.R.O.,Polytechnic Institute of Viseu | Ferreira R.A.C.,Lusophone University of Humanities and Technologies | Torres D.F.M.,University of Aveiro
Signal Processing | Year: 2011

We introduce a discrete-time fractional calculus of variations on the time scale (hℤ)a,a∈ℝ,h>0. First and second order necessary optimality conditions are established. Examples illustrating the use of the new Euler-Lagrange and Legendre type conditions are given. They show that solutions to the considered fractional problems become the classical discrete-time solutions when the fractional order of the discrete-derivatives are integer values, and that they converge to the fractional continuous-time solutions when h tends to zero. Our Legendre type condition is useful to eliminate false candidates identified via the Euler-Lagrange fractional equation. © 2010 Elsevier B.V. All rights reserved.

Ferreira R.A.C.,Lusophone University of Humanities and Technologies
Computers and Mathematics with Applications | Year: 2011

In this paper, we investigate the existence of positive solutions to the nonlinear q-fractional boundary value problem (Dqαy)(x)=-f(x,y(x)), 0

Sardinha L.B.,The Interdisciplinary Center | Marques A.,The Interdisciplinary Center | Martins S.,Lusophone University of Humanities and Technologies | Palmeira A.,The Interdisciplinary Center | And 2 more authors.
BMC Pediatrics | Year: 2014

Background: In addition to the benefits on physical and mental health, cardiorespiratory fitness has shown to have positive effects on cognition. This study aimed to investigate the relationship between cardiorespiratory fitness and body weight status on academic performance among seventh-grade students.Methods: Participants included 1531 grade 7 students (787 male, 744 female), ranging in age from 12 to 14 years (Mage = 12.3 ± 0.60), from 3 different cohorts. Academic performance was measured using the marks students had, at the end of their academic year, in mathematics, language (Portuguese), foreign language (English), and sciences. To assess cardiorespiratory fitness the Progressive Aerobic Cardiovascular Endurance Run, from Fitnessgram, was used as the test battery. The relationship between academic achievement and the independent and combined association of cardiorespiratory fitness/weight status was analysed, using multinomial logistic regression.Results: Cardiorespiratory fitness and weight status were independently related with academic achievement. Fit students, compared with unfit students had significantly higher odds for having high academic achievement (OR = 2.29, 95% CI: 1.48-3.55, p < 0.001). Likewise, having a normal weight status was also related with high academic achievement (OR = 3.65, 95% CI: 1.82-7.34, p < 0.001).Conclusions: Cardiorespiratory fitness and weight status were independently and combined related to academic achievement in seventh-grade students independent of the different cohorts, providing further support that aerobically fit and normal weight students are more likely to have better performance at school regardless of the year that they were born. © 2014 Sardinha et al.

Ferreira R.A.C.,Lusophone University of Humanities and Technologies
Wireless Personal Communications | Year: 2013

In this paper we raise and discuss a problem from the analysis done in Moen et al. (ACM SIGMOBILE Comput Commun Rev 8(2):76-83, 2004) about some weaknesses in the key scheduling in Wi-Fi protected access (WPA). © 2012 Springer Science+Business Media, LLC.

Almeida R.,University of Aveiro | Ferreira R.A.C.,University of Aveiro | Ferreira R.A.C.,Lusophone University of Humanities and Technologies | Torres D.F.M.,University of Aveiro
Acta Mathematica Scientia | Year: 2012

In this article, we study isoperimetric problems of the calculus of variations with left and right Riemann-Liouville fractional derivatives. Both situations when the lower bound of the variational integrals coincide and do not coincide with the lower bound of the fractional derivatives are considered. © 2012 Wuhan Institute of Physics and Mathematics.

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