Vilanov R.,Autonomous University of Barcelona |
Alfaro V.M.,University of San Jose
RIAI - Revista Iberoamericana de Automatica e Informatica Industrial | Year: 2011
This paper presents a general overview of the existing approaches used to obtain a robust proportional integral derivative (PID) controller. The rigid and particular structure imposed by the PID controller, have been the main reason for its vast use in industrial applications but at the same time impose several constrains to include robustness considerations into its design. Nowadays, the spectrum of possibilities for the robust design of a PID controller is very wide and may be faced with practically any approach, specifically with any robust control approach. At this respect, it is important to distinguish between tuning methods and tuning rules been of interest, in the PID controller case, the development of simple tuning rules that at the same time guarantee its robustness. Previously to this classification, it is important to state how the robustness is measured and represented. Accordingly, how the design specifications are finally formulated. The paper also reviews other newer issues proposed in the PID literature and related with the control system robustness, as are its achievement and the controller's fragility. © 2011 CEA.
Avalos G.,University of San Jose |
Mulkey S.S.,Unity College
American journal of botany | Year: 2014
PREMISE OF THE STUDY: Few studies have analyzed the physiological performance of different life stages and the expression of ontogenetic niche shifts in lianas. Here, we analyzed the photosynthetic and morphological acclimation of seedlings of Stigmaphyllon lindenianum, Combretum fruticosum, and Bonamia trichantha to distinctive light conditions in a tropical dry forest and compared their response with the acclimation response of adult canopy lianas of the same species. We expected acclimation to occur faster through changes in leaf photochemistry relative to adaptation in morphology, consistent with the life history strategies of these lianas.•METHODS: Seedlings were assigned to the following light treatments: high light (HH), low light (LL), sun to shade (HL), and shade to sun (LH) in a common garden. After 40 d, HL and LH seedlings were exposed to opposite light treatments. Light response curves, the maximum photosynthetic rate in the field (Amax), and biomass allocation were monitored for another 40 d on leaves expanded before transfer.•KEY RESULTS: Photosynthetic responses, Amax, and biomass of Stigmaphyllon and Combretum varied with light availability. Physiological characters were affected by current light environment. The previous light environment (carryover effects) only influenced Amax. Morphological characters showed significant carryover effects. Stigmaphyllon showed high morphological and physiological plasticity. Sun-exposed seedlings of this liana increased stem biomass and switched from self-supporting to climbing forms.•CONCLUSIONS: Acclimation in seedlings of these lianas is consistent with the response of adult lianas in the canopy in direction, but not in magnitude. There was no evidence for ontogenetic niche shifts in the acclimation response. © 2014 Botanical Society of America, Inc.
Tsuruike M.,University of San Jose |
Ellenbecker T.S.,Physiotherapy Scottsdale Sports ClinicAZ
Journal of Athletic Training | Year: 2015
Context: Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective: To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design: Cross-sectional study. Setting: Health Science Laboratory. Patients or Other Participants: A total of 16 uninjured, healthy, active, male college students (age 1/4 19.5 6 1.2 years, height 1/4 173.1 6 6.5 cm, weight 1/4 68.8 6 6.6 kg). Main Outcome Measure(s): Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results: Significant interactions in electromyographic activity were observed between intensities and exercises (P , .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery freemotion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions: Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited.
Zaglul J.A.,University of San Jose
Frontiers in Life Science | Year: 2016
Institutions of higher education have an important role in preparing the professionals that society needs to confront the challenges of the twenty-first century. A transformation of traditional higher education models must occur to ensure the relevance and impact of university education for the individual and society. This can be achieved by taking a student-centered approach that encourages questions and criticisms and provides students with opportunities to discover knowledge through experience. Additionally, the doors of the university must remain open to students of diverse backgrounds to ensure that the benefits of advanced education permeate society. For the past 25 years, EARTH University – a private, not for profit, international university located in Costa Rica – has implemented an innovative educational model to accomplish its unique mission ‘to form leaders with ethical values to contribute to sustainable development and to construct a prosperous and just society’. The EARTH model focuses on four formative areas: scientific and technical knowledge, social and environmental awareness, ethics and values, and entrepreneurship. More than 2000 professionals from over 30 countries in the Americas, the Caribbean, Africa, Asia, and Europe are graduates of the EARTH model with proven results. This article presents the EARTH case as a model for study. © 2016 Informa UK Limited, trading as Taylor & Francis Group
Wallace D.E.,University of Costa Rica |
Wallace D.E.,University of San Jose
Microbiology (Reading, England) | Year: 2014
Leaf-cutting ants (genera Atta and Acromyrmex) cultivate a specialized fungus for food in underground chambers employing cut plant material as substrate. Parasitism occurs in this agricultural system and plays an important role in colony fitness. The microfungi Escovopsis, a specialized mycoparasite of the fungal cultivar, is highly prevalent among colonies. In this study, we tested the antagonistic activity of several Escovopsis strains from different geographical areas in Costa Rica. We employed a combination of laboratory tests to evaluate virulence, including pure culture challenges, toxicity to fungus garden pieces and subcolony bioassays. We also performed a phylogenetic analysis of these strains in order to correlate their virulence with the genetic structure of this population. The bioassays yielded results consistent between each other and showed significant differences in antagonistic activity among the parasites evaluated. However, no significant differences were found when comparing the results of the bioassays according to the source of the ants' fungal cultivar. The phylogenetic analyses were consistent with these results: whilst the fungal cultivar phylogeny showed a single clade with limited molecular variation, the Escovopsis phylogeny yielded several clades with the most virulent isolates grouping in the same well-supported clade. These results indicate that there are Escovopsis strains better suited to establish their antagonistic effect, whilst the genetic homogeneity of the fungal cultivars limits their ability to modulate Escovopsis antagonism. These findings should be taken into consideration when evaluating the potential of Escovopsis isolates as biocontrol agents for this important agricultural pest in the Neotropics. © 2014 The Authors.