Influência de culturas antecessoras na disponibilidade de nitrogênio do solo para a cultura do algodão.

Um dos fatores importantes a ser considerado no manejo da adubação nitrogenada é a cultura antecessora. O objetivo desse trabalho, conduzido em Santa Helena de Goiás, foi medir a influência de culturas antecessoras na disponibilidade de nitrogênio (N) inorgânico no solo e na resposta do algodoeiro à adubação nitrogenada. O experimento foi instalado em parcelas subdivididas com quatro repetições. Nas parcelas foram cultivadas as culturas antecessoras milho, soja, algodão e Brachiaria decumbens; e nas subparcelas foram aplicadas cinco doses de nitrogênio (0, 40, 80, 120 e 160 kg ha-1 de N) no algodoeiro cultivado em sucessão. O algodoeiro em sucessão à soja e ao algodão necessita de menor quantidade de fertilizante nitrogenado, em comparação com a sucessão à braquiária e ao milho. Durante o ciclo do algodoeiro a presença de resíduos de soja favorece a mineralização líquida do nitrogênio do solo, tornando-o disponível nos primeiros estádios de desenvolvimento da planta. Os resíduos de B. decumbens favorecem a imobilização do N na biomassa microbiana do solo

Adubação NPK do algodoeiro em cultivo adensado de safrinha no Cerrado de Goiás - safra 2010/11.

O objetivo desse trabalho foi definir doses de NPK para adubação de manutenção do algodão de safrinha adensado, nas condições do Cerrado de Goiás, em função da fertilidade do solo, da expectativa de produtividade e das quantidades exportadas desses nutrientes pela cultura

Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals

A Unifying Theory of Biological Function

A new theory that naturalizes biological function is explained and compared with earlier etiological and causal role theories. Etiological theories explain functions from how they are caused over their evolutionary history. Causal role theories analyze how functional mechanisms serve the current capacities of their containing system. The new proposal unifies the key notions of both kinds of theories, but goes beyond them by explaining how functions in an organism can exist as factors with autonomous causal efficacy. The goal-directedness and normativity of functions exist in this strict sense as well. The theory depends on an internal physiological or neural process that mimics an organism’s fitness, and modulates the organism’s variability accordingly. The structure of the internal process can be subdivided into subprocesses that monitor specific functions in an organism. The theory matches well with each intuition on a previously published list of intuited ideas about biological functions, including intuitions that have posed difficulties for other theories

Cognitive appraisal of environmental stimuli induces emotion-like states in fish

The occurrence of emotions in non-human animals has been the focus of debate over the years. Recently, an interest in expanding this debate to non-tetrapod vertebrates and to invertebrates has emerged. Within vertebrates, the study of emotion in teleosts is particularly interesting since they represent a divergent evolutionary radiation from that of tetrapods, and thus they provide an insight into the evolution of the biological mechanisms of emotion. We report that Sea Bream exposed to stimuli that vary according to valence (positive, negative) and salience (predictable, unpredictable) exhibit different behavioural, physiological and neuromolecular states. Since according to the dimensional theory of emotion valence and salience define a two-dimensional affective space, our data can be interpreted as evidence for the occurrence of distinctive affective states in fish corresponding to each the four quadrants of the core affective space. Moreover, the fact that the same stimuli presented in a predictable vs. unpredictable way elicited different behavioural, physiological and neuromolecular states, suggests that stimulus appraisal by the individual, rather than an intrinsic characteristic of the stimulus, has triggered the observed responses. Therefore, our data supports the occurrence of emotion-like states in fish that are regulated by the individual's perception of environmental stimuli.European Commission [265957 Copewell]; Fundacao para a Ciencia e Tecnologia [SFRH/BD/80029/2011, SFRH/BPD/72952/2010]info:eu-repo/semantics/publishedVersio

TRANSIENT MODELING OF A SMALL HYDROKINETIC TURBINE

In recent years, great attention has been given to the study of hydrokinetic turbines for power generation. Such importance is due to the use of clean energy technology by using renewable sources. Therefore, this work aims to present a relevant methodology for the efficient design of horizontal-axis hydrokinetic turbines with variable rotational speed. This methodology includes the Blade Element Method (BEM) for determining the turbine power coefficient, since BEM is widely used in the hydrokinetic turbine design due to its good agreement with experimental data. In addition, the dynamic equation of the driveline is used, taking into account the BEM to provide the rotor hydrodynamic torque coupled with the drive train model, including the multiplier and the electric generator. In this case, the modeling of the whole system comprises the hydrodynamic information of the rotor, the mass-moment of inertia, frictional losses and electromagnetic torque imposed by the generator. The theoretical results were obtained for the transient rotational speed and compared with field data measured from small hydrokinetic turbine installed at the Arapiranga-Açu creek, which is located in the city of Acará, Pará, Brazil

Cortisol coregulation in fish

Cortisol coregulation, which is the up- or down-regulation of partners’ physiological stress responses, has been described for individuals with strong attachment bonds, e.g. parents and their children, and romantic relationship partners. Research into moderating effects on cortisol coregulation suggests stronger covariation among distressed partners. Whether cortisol coregulation is unique to humans or can also be found in other species that share universal features of the vertebrate stress response remains unexplored. Using a repeated measures approach and non-invasive waterborne hormone analysis, we test the hypothesis that dyads of three-spined stickleback fish (Gasterosteus aculeatus) coregulate their cortisol levels in shared environments. Dyadic cortisol levels were unrelated when cohabiting (home tank), but significantly covaried when sharing a more stressful (as indicated by higher cortisol levels) environment (open field). Time-lag analysis further revealed that open field cortisol levels were predicted by partner’s cortisol levels prior to the shared experience. To our knowledge, this study provides the first evidence for coregulatory processes on cortisol responses in a non-human animal that lacks strong bonds and social attachment relationships, suggesting a shared evolutionary origin of cortisol coregulation in vertebrates. From an adaptive perspective, cortisol coregulation may serve to reduce risk in challenging, potentially threatening situations

Monotonicity of Fitness Landscapes and Mutation Rate Control

A common view in evolutionary biology is that mutation rates are minimised. However, studies in combinatorial optimisation and search have shown a clear advantage of using variable mutation rates as a control parameter to optimise the performance of evolutionary algorithms. Much biological theory in this area is based on Ronald Fisher's work, who used Euclidean geometry to study the relation between mutation size and expected fitness of the offspring in infinite phenotypic spaces. Here we reconsider this theory based on the alternative geometry of discrete and finite spaces of DNA sequences. First, we consider the geometric case of fitness being isomorphic to distance from an optimum, and show how problems of optimal mutation rate control can be solved exactly or approximately depending on additional constraints of the problem. Then we consider the general case of fitness communicating only partial information about the distance. We define weak monotonicity of fitness landscapes and prove that this property holds in all landscapes that are continuous and open at the optimum. This theoretical result motivates our hypothesis that optimal mutation rate functions in such landscapes will increase when fitness decreases in some neighbourhood of an optimum, resembling the control functions derived in the geometric case. We test this hypothesis experimentally by analysing approximately optimal mutation rate control functions in 115 complete landscapes of binding scores between DNA sequences and transcription factors. Our findings support the hypothesis and find that the increase of mutation rate is more rapid in landscapes that are less monotonic (more rugged). We discuss the relevance of these findings to living organisms

Interplay between pleiotropy and secondary selection determines rise and fall of mutators in stress response

Dramatic rise of mutators has been found to accompany adaptation of bacteria in response to many kinds of stress. Two views on the evolutionary origin of this phenomenon emerged: the pleiotropic hypothesis positing that it is a byproduct of environmental stress or other specific stress response mechanisms and the second order selection which states that mutators hitchhike to fixation with unrelated beneficial alleles. Conventional population genetics models could not fully resolve this controversy because they are based on certain assumptions about fitness landscape. Here we address this problem using a microscopic multiscale model, which couples physically realistic molecular descriptions of proteins and their interactions with population genetics of carrier organisms without assuming any a priori fitness landscape. We found that both pleiotropy and second order selection play a crucial role at different stages of adaptation: the supply of mutators is provided through destabilization of error correction complexes or fluctuations of production levels of prototypic mismatch repair proteins (pleiotropic effects), while rise and fixation of mutators occur when there is a sufficient supply of beneficial mutations in replication-controlling genes. This general mechanism assures a robust and reliable adaptation of organisms to unforeseen challenges. This study highlights physical principles underlying physical biological mechanisms of stress response and adaptation

Qualidade fisiológica de lotes comerciais de sementes de maracujazeiro-doce armazenadas por longo período.

O teste padrão de germinação fornece o potencial máximo para a formação de plântulas normais, já que, é conduzido nas condições ideais. Para a disponibilidade de sementes durante todo o ano, se faz necessário o armazenamento das mesmas. Ao longo do período de armazenamento das sementes, a qualidade fisiológica sofre redução, podendo ser maior ou menor dependendo da espécie, do genótipo e das condições do armazenamento. A Embrapa e parceiros têm desenvolvido um programa de melhoramento genético de diferentes espécies do gênero Passiflora com o lançamento de algumas cultivares. Entre as cultivares lançada pela Embrapa e parceiros está a BRS Mel do Cerrado - BRS MC (Passiflora alata), (EMBRAPA, 2020). Com a oferta de mais cultivares de maracujazeiro, aumenta-se também a demanda por sementes com qualidade genética, fisiológica e fitossanitária. E com isso, também, é importante uma logística adequada para a comercialização dessas sementes, além de informações sobre a germinação, vigor e armazenamento. Trabalhos vem sendo realizados com diferentes espécies do gênero Passiflora têm mostrado o efeito do genótipo sobre a viabilidade ou germinação de sementes (VIANA, et al., 2016; OLIVEIRA, et al., 2016; 2020). Desse modo, não é possível generalizar as informações para a espécie, mas é importante considerar o genótipo que está sendo analisado, bem como as condições e tempo de armazenamento. Neste contexto, objetivou-se avaliar a qualidade fisiológica de lotes de sementes e plântulas da cultivar BRS Mel do Cerrado após longos períodos de armazenament