BIOECONOMIC MANAGEMENT OF RED SWAMP CRAYFISH (PROCAMBARUS CLARKII) IN THE PRESENCE OF ENVIRONMENTAL EXTERNALITIES

Red swamp crayfish (Procambarus clarkii) is a valuable renewable resource which creates significant negative externalities to its environment. Crayfish can cause severe crop damage by burrowing in fields and using irrigation systems to spread. These crayfish are resistant to normal dosages of pesticides which are harmful to fish and birds, can endure months of dryness, and live in a low oxygen environment. This paper presents a simple bioeconomic model for optimal use of the red swamp crayfish accounting for its value in consumption, adapting Plourde's (1970) model to include the negative externalities.Resource /Energy Economics and Policy,

Psycholinguistic Correlates of Symbol Grounding in Dictionaries

A dictionary can be represented as a directed graph with links from defining to defined words. The minimal feedback vertex sets (MinSets, Ms) of a dictionary graph are the smallest sets of words from which all the rest can be defined. We computed Ms for four English dictionaries. The words in the dictionary components revealed by our graph-theoretic analysis differ in their psycholinguistic correlates. Every MinSet has a C-part that is younger and more frequent and an S-part, that is more concrete. To understand the functional role of these components will require a close study of the words themselves, and how they are combined into definitions. We can already conclude that the closer a word is to the MinSets that can define all other words, the more concrete and frequent the word is likely to be, and the earlier it is likely to have been learned. This is what one would expect if the words in the MinSets were the ones that had been acquired through direct sensorimotor grounding

The Latent Structure of Dictionaries

How many words (and which ones) are sufficient to define all other words? When dictionaries are analyzed as directed graphs with links from defining words to defined words, they reveal a latent structure. Recursively removing all words that are reachable by definition but that do not define any further words reduces the dictionary to a Kernel of about 10%. This is still not the smallest number of words that can define all the rest. About 75% of the Kernel turns out to be its Core, a Strongly Connected Subset of words with a definitional path to and from any pair of its words and no word’s definition depending on a word outside the set. But the Core cannot define all the rest of the dictionary. The 25% of the Kernel surrounding the Core consists of small strongly connected subsets of words: the Satellites. The size of the smallest set of words that can define all the rest (the graph’s Minimum Feedback Vertex Set or MinSet) is about 1% of the dictionary, 15% of the Kernel, and half-Core, half-Satellite. But every dictionary has a huge number of MinSets. The Core words are learned earlier, more frequent, and less concrete than the Satellites, which in turn are learned earlier and more frequent but more concrete than the rest of the Dictionary. In principle, only one MinSet’s words would need to be grounded through the sensorimotor capacity to recognize and categorize their referents. In a dual-code sensorimotor-symbolic model of the mental lexicon, the symbolic code could do all the rest via re-combinatory definition

Changes in Cardiac Tone Regulation with Fatigue after Supra-Maximal Running Exercise

To investigate the effects of fatigue and metabolite accumulation on the postexercicse parasympathetic reactivation, 11 long-sprint runners performed on an outdoor track an exhaustive 400 m long sprint event and a 300 m with the same 400 m pacing strategy. Time constant of heart rate recovery (HRRτ), time (RMSSD), and frequency (HF, and LF) varying vagal-related heart rate variability indexes were assessed during the 7 min period immediately following exercise. Biochemical parameters (blood lactate, pH, PO2, PCO2, SaO2, and HCO3−) were measured at 1, 4 and 7 min after exercise. Time to perform 300 m was not significantly different between both running trials. HHRτ measured after the 400 m running exercise was longer compared to 300 m running bouts (183.7 ± 11.6 versus 132.1 ± 9.8 s, P < 0.01). Absolute power density in the LF and HF bands was also lower after 400 m compared to the 300 m trial (P < 0.05). No correlation was found between biochemical and cardiac recovery responses except for the PO2 values which were significantly correlated with HF levels measured 4 min after both bouts. Thus, it appears that fatigue rather than metabolic stresses occurring during a supramaximal exercise could explain the delayed postexercise parasympathetic reactivation in longer sprint runs

Orientações terapêuticas para o tratamento da Doença de Crohn

Dissertação de mestrado, Ciências Farmacêuticas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014A Doença de Crohn é uma doença inflamatória crónica do intestino, de causa desconhecida, mas associada a fatores genéticos, ambientais e imunológicos, que envolve qualquer parte do revestimento do trato gastrointestinal (principalmente, o íleo terminal ou o cólon proximal) e atinge, normalmente, toda a espessura desta parede, o que pode provocar úlceras no seu revestimento interior. Curiosamente, a incidência e a prevalência desta doença são das mais altas no Reino Unido, no norte da Europa e na América do Norte e, por outro lado, ambos os sexos são igualmente afetados. Dado não haver cura para a Doença de Crohn, o principal objetivo da terapia é induzir e manter a remissão. Quanto aos objetivos secundários, estes incluem a melhoria e minimização dos sintomas, a resolução da inflamação aguda do trato gastrointestinal, a prevenção de recaídas, o tratamento e prevenção de manifestações extraintestinais e, finalmente, a melhoria da qualidade de vida. Deste modo, as opções de tratamento farmacológico atuais para a Doença de Crohn incluem corticosteroides (como a prednisolona ou o budesonida), aminossalicilatos e seus derivados (a sulfassalazina e a messalazina), os imunossupressores (como a azatioprina, a 6-mercaptopurina ou o metotrexato), os antibióticos (a ciprofloxacina e o metronidazol, entre outros) e os agentes biológicos (principalmente, o adalimumab, o infliximab e, recentemente aprovado na Europa, o vedolizumab). As funções dos diferentes tipos de fármacos utilizados são variadas, tais como: a indução da remissão e a sua manutenção, o tratamento de infeções e/ou fístulas relacionadas com a Doença de Crohn, entre outros. Deste modo, as orientações terapêuticas para o tratamento desta doença inflamatória intestinal, baseadas na eficácia e no perfil dos efeitos secundários dos fármacos, incluindo a terapêutica não farmacológica concomitante, são cruciais para uma melhoria na saúde nos doentes com Doença de Crohn

Identification of mechanical systems with local nonlinearities through discrete-time Volterra series and Kautz functions

peer reviewedMathematical modeling of mechanical structures is an important research area in structural dynamics. One of the goals of this area is to obtain a model that accurately predicts the dynamics of the system. However, the nonlinear eff ects caused by large displacements and boundary conditions like gap, backlash or joint are not as well understood as the linear counterpart. This paper identifies a non-parametric discrete-time Volterra model of a benchmark nonlinear structure consisting of a cantilever beam connected to a thin beam at its free end. Time-domain data experimentally measured are used to identify the Volterra kernels, which are expanded with orthogonal Kautz functions to facilitate the identification process. The nonlinear parameters are then estimated through a model updating process involving optimization of the residue between the numerical and experimental kernels. The advantages and drawbacks of the Volterra series for modeling the behavior of nonlinear structures are finally indicated with suggestions to overcome the disadvantages found during the tests