229 research outputs found

    Complete integrability of information processing by biochemical reactions

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    Statistical mechanics provides an effective framework to investigate information processing in biochemical reactions. Within such framework far-reaching analogies are established among (anti-) cooperative collective behaviors in chemical kinetics, (anti-)ferromagnetic spin models in statistical mechanics and operational amplifiers/flip-flops in cybernetics. The underlying modeling -- based on spin systems -- has been proved to be accurate for a wide class of systems matching classical (e.g. Michaelis--Menten, Hill, Adair) scenarios in the infinite-size approximation. However, the current research in biochemical information processing has been focusing on systems involving a relatively small number of units, where this approximation is no longer valid. Here we show that the whole statistical mechanical description of reaction kinetics can be re-formulated via a mechanical analogy -- based on completely integrable hydrodynamic-type systems of PDEs -- which provides explicit finite-size solutions, matching recently investigated phenomena (e.g. noise-induced cooperativity, stochastic bi-stability, quorum sensing). The resulting picture, successfully tested against a broad spectrum of data, constitutes a neat rationale for a numerically effective and theoretically consistent description of collective behaviors in biochemical reactions.Comment: 24 pages, 10 figures; accepted for publication in Scientific Report

    The rupestrian churches in the monastery of Geghard, Armenia

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    The monastery of Geghard is of particular importance, as it is the only consecrated monument in Armenia to be half built and half carved into the rock. Probably founded in the first centuries its maximum expansion had in the thirteenth century, and from that moment it is as if it had almost crystallized in its ancient appearance. In the year 2000 UNESCO included it in the World Heritage sites. This multidisciplinary research group saw its great potential and took it as a case study, starting from digital surveying, in parallel with the historical-artistic investigation. In this paper we want to expose the first elaborations and the first observations arising from the recent survey campaign, the first cognitive stage prior to the subsequent ‘in-depth’ processing of the data

    Recovery of degraded areas revegeted with Acacia mangium and Eucalyptus with special reference to organic matter humification

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    Humidified fractions of organic matter and soil microorganism populations are used as environmental quality indicators. This work aimed to study the changes in chemical and microbiological soil attributes, as well as in the humidified fractions, of the organic matter in a substrate from a clay extraction area cropped with Brachiaria mutica, Acacia mangium and Eucalyptus. In the Eucalyptus area, the P contents increased linearly with planting time. However, only at the twelfth year, differences between Eucalyptus and B. mutica areas have occurred. In the A. mangium area, such differences in the P content occurred at the third year with increment of 43%, at the 0-10 cm layer, in relation to B. mutica. Also, at the 0-10 cm layer, the total carbon contents were 98%, 78%, 70% and 40% higher than those found in Eucalyptus with three, five, twelve years of age and in the B. mutica area, respectively. Such increments also occurred in the humidified fractions, especially in the fulvic acids (C FA). The population of microorganisms was higher in the A. mangium area, mainly in the summer, where it was observed a positively correlation with total carbon (total bacteria, r = 0.96**, total fungi, r = 0.91*, and phosphate solubilizer microorganisms, r = 0.98**) and with the C FA fraction (total bacteria r = 0.96**, total fungi, r = 0.90*, and phosphate solubilizer microorganisms, r = 0.98**). The use of A. mangium led to improvements in the chemical and microbiological soil attributes in the substrateFrações da matéria orgânica humificada e a população de microrganismos do solo são utilizadas como indicadores da qualidade ambiental. Objetivou-se verificar mudanças nos atributos químicos, microbiológicos e nas frações humificadas da matéria orgânica em substrato de cava de extração de argila com cobertura de Brachiaria mutica, Acacia mangium e Eucalyptus. Nas áreas de Eucalyptus os teores de P aumentaram linearmente em função do tempo de plantio, porém somente no décimo segundo ano diferiu da B. mutica. Na área com A. mangium tais diferenças ocorreram no terceiro ano, com incremento de 43% na camada de 0-10 cm em relação à B. mutica. Ainda, na camada de 0-10 cm os teores de carbono total foram maiores 98%, 78%, 70% e 40% em relação ao Eucalyptus com três, cinco, doze anos, e B. mutica, respectivamente. Tais incrementos também ocorreram nas frações humificadas, principalmente nos ácidos fúlvicos (C AF). A população de microrganismos foi maior na cobertura com A. mangium, acentuadamente no verão; correlacionando-se com o carbono total (bactérias totais, r = 0,96**; fungos totais, r = 0,91*; e solubilizadores de fosfato, r = 0,98**) e com a fração C AF (bactérias totais, r = 0,96**; fungos totais, r = 0,90*; e solubilizadores de fosfato, r = 0,98**). O uso da A. mangium proporcionou melhoria nos atributos químicos e microbiológicos do substrato da cava de extração de argila

    Un romanico tra virgolette. Il Santuario di Santa Lucia a Sassinoro

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    Santa Lucia a Sassinoro Storia del santuario La chiesa della Grotta Il progetto La realizzazione e i materiali La grotta Il campanile A proposito del romani Bibliografi

    Event-based MPC for propofol administration in anesthesia

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    Background and Objective : The automatic control of anesthesia is a demanding task mostly due to the presence of nonlinearities, intra- and inter-patient variability and specific clinical requirements to be meet. The traditional approach to achieve the desired depth of hypnosis level is based on knowledge and experience of the anesthesiologist. In contrast to a typical automatic control system, their actions are based on events that are related to the effect of the administrated drug. Thus, it is interesting to build a control system that will be able to mimic the behavior of the human way of actuation, simultaneously keeping the advantages of an automatic system.Methods : In this work, an event-based model predictive control system is proposed and analyzed. The nonlinear patient model is used to form the predictor structure and its linear part is exploited to design the predictive controller, resulting in an individualized approach. In such a scenario, the BIS is the controlled variable and the propofol infusion rate is the control variable. The event generator governs the computation of control action applying a dead-band sampling technique. The proposed control architecture has been tested in simulation considering process noise and unmeasurable disturbances. The evaluation has been made for a set of patients using nonlinear pharmacokinetic/pharmacodynamic models allowing realistic tests scenarios, including inter- and intra-patient variability.Results For the considered patients dataset the number of control signal changes has been reduced of about 55% when compared to the classical control system approach and the drug usage has been reduced of about 2%. At the same time the control performance expressed by the integrated absolute error has been degraded of about 11%.Conclusions : The event-based MPC control system meets all the clinical requirements. The robustness analysis also demonstrates that the event-based architecture is able to satisfy the specifications in the presence of significant process noise and modelling errors related to inter- and intra-patient variability, providing a balanced solution between complexity and performance. (c) 2022 Elsevier B.V. All rights reserved

    Production of Acacia plants colonized with mycorrhizas and rhizobium in different recipients

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    Realizou-se um experimento em casa de vegetação, com o objetivo de avaliar diferentes métodos na produção de mudas de Acacia mangium Willd, colonizadas com fungos micorrízicos arbusculares (FMAs) e rizóbio. O delineamento experimental foi o inteiramente casualizado num esquema fatorial 4x2 (controle, FMAs, rizóbio e FMAs + rizóbio x blocos prensados e tubetes de plástico), com seis repetições. Os blocos prensados foram confeccionados com substratos orgânicos (bagaço de cana + torta de filtro de usina açucareira) e vermiculita, colocados em fôrma metálica de 60x40x20 cm e prensados a 10 kgf cm-2, a fim de proporcionar agregação do material. A inoculação do rizóbio foi realizada com estirpe selecionada para a espécie (Br 3609, Br 6009). A inoculação de FMAs foi feita no momento da confecção dos blocos. Mudas de Acacia mangium que receberam inóculo de FMAs + rizóbio e produzidas em blocos prensados apresentaram maior produção de matéria seca e conteúdo de N na parte aérea. O conteúdo de P na parte aérea é significativamente maior somente nas mudas infectadas com os FMAs, independentemente do tipo de recipiente.A greenhouse experiment was carried out in order to evaluate different methods to produce Acacia mangium Willd plant seedlings, inoculated with arbuscular mycorrhizal fungi (AMF) and rhizobium. A completely randomized design in a factorial scheme 4x2 (control, AMF, rhizobium and AMF + rhizobium x pressed blocks and plastic tubes), with six repetitions was used. The pressed blocks used to produce Acacia mangium plants were made with organic residue from sugarcane (sugarcane bagasse + filter cake) and vermiculite. The inoculation with rhizobium was done with selected strain (Br 3609, Br 6009). The inoculation with AMF was done at the time when pressed blocks were made. Acacia mangium plants inoculated with both AMF + rhizobium led to a significant increase in dry matter yield and N content of shoot plants, only in pressed blocks. Phosphorus content of shoot plants is significantly higher in seedlings inoculated only with AMF, and it is independent of the plant production system

    MPC for Propofol Anesthesia: the Noise Issue

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    The design of automatic control systems for general anesthesia is a challenging task due to the severe safety requirements and process constraints. This is even more complex when model-based control techniques are used due to the significant variability of the process model. Additionally, issues like noisy measurements and interference also influence the control system overall performance. In this context, adequate filtering and control system sampling period selection should be analyzed to test their influence on the controller. In this paper, an MPC system for the depth of hypnosis, where the BIS signal is used as a controlled variable, is analyzed. The main purpose is to test and evaluate how the process noise affects the performance of the control system. The analysis is performed in a simulation study using a dataset of virtual patients representative of a wide population. Results show that a satisfactory performance is obtained when the noise is explicitly taken into account in the controller tuning procedure for a specific sampling period

    Long-Term Results at 10 Years of Pouch Resizing for Roux-en-Y Gastric Bypass Failure

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    Background: Roux-en-Y gastric bypass (RYGB) is currently one of the most performed bariatric procedures and it is associated with rapid weight loss. However, weight loss failure and weight regain after RYGB occurs in approximately 30% and 3-5% of patients, respectively, and represent a serious issue. RYGB pouch resizing is a surgical option that may be offered to selected patients with RYGB failure. The aim of this study is to assess long-term results of pouch resizing for RYGB failure. Materials and Methods: From February 2009 to November 2011, 20 consecutive patients underwent gastric pouch resizing for RYGB failure in our tertiary bariatric center. The primary outcome was the rate of failure (%EWL < 50% with at least one metabolic comorbidity) after at least 10 years from pouch resizing. Gastroesophageal Reflux Disease (GERD) was also assessed. Results: Twenty patients (18 women (90%)) were included and seventeen (85%) joined the study. The failure rate of pouch resizing was 47%. Mean %EWL and mean BMI were 47%, and 35.1 kg/m(2), respectively. Some of the persistent co-morbidities further improved or resolved after pouch resizing. Seven patients (41%) presented GERD requiring daily PPI with a significantly lower GERD-HQRL questionnaire score after pouch resizing (p < 0.001). Conclusion: Pouch resizing after RYGB results in a failure rate of 47% at the 10-year follow-up while the resolution of comorbidities is maintained over time despite a significant weight regain

    Isotopic variations of carbon and nitrogen and their implications on the conversion of Cerrado vegetation into pasture

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    As conversões de vegetação natural em pastagem podem, em um curto intervalo de tempo, alterar o estoque de carbono e a abundância natural de Î´13C no solo. O objetivo deste trabalho foi avaliar alterações nos estoques de carbono (C) e nitrogênio (N) e na abundância natural de δ13C e δ15N no Argissolo Vermelho distrófico (Acrisolo) em uma área de vegetação natural e pastagem plantada no Cerrado em Aquidauana (MS). Para isso, foram avaliadas uma Ã¡rea de pastagem (PA), cultivada durante 25 anos com Urochloa brizantha, e uma área de vegetação natural (VN). Foram coletadas amostras de solo em intervalos de profundidade de 0,05 m até 0,60 m, e a partir delas foram determinados os atributos físicos, os estoques de C e N (EstC e EstN) e as variações isotópicas de δ13C e δ15N do solo. Na camada de 0–0,05 m, os maiores estoques de C e N ocorreram na VN; 21,99 e 1,9 Mg ha-1, respectivamente. Na conversão para PA, 14,62 Mg ha-1 do EstC e 1,36 Mg ha-1 do EstN foram perdidos na camada de 0–0,05 m. A área com PA apresentou maior enriquecimento isotópico do δ13C nas camadas de 0–0,05 e 0,05–0,10 m, cujos valores foram de -18,3 e -17,4‰, respectivamente, enquanto, nas demais camadas, os valores isotópicos diminuíram com a mistura entre C de plantas C3 e C4. A VN apresentou enriquecimento nos sinais isotópicos nas camadas 0,25–0,30 até 0,40–0,45 m, com valores entre -21,74 e -21,54‰, respectivamente, o que é característico de vegetação mista de plantas C3 e C4. Os valores de Î´15N apresentaram enriquecimento isotópico de acordo com o aumento da profundidade, indicando maior mineralização da matéria orgânica do solo em ambas as áreas. A conversão do Cerrado em pastagem e, consequentemente, sua fragmentação, provoca impactos negativos na capacidade de sequestro e armazenamento do C e N, tanto na pastagem quanto na vegetação natural.Conversions of natural vegetation into pasture can, in a short time, change the carbon stock and the natural abundance of δ13C in the soil. The objective of this study was to evaluate changes in carbon (C) and nitrogen (N) stocks, as well as in the natural abundance of δ13C and δ15N of Argissolo Vermelho distrófico (Acrisol), in an area of natural vegetation and planted pasture in the Cerrado region of Aquidauana (MS), Brazil. In order to do this, an area of pasture (PA), cultivated for 25 years with Urochloa brizantha, and an area of natural vegetation (NV) were evaluated. Soil samples were collected at intervals of 0.05 m up to 0.60 m depth, and physical attributes, C and N stocks (CSt and NSt) and isotopic variations of δ13C and δ15N of soil were determined. In the 0–0.05 m layer, the highest C and N stocks occurred in NV, 21.99 and 1.9 Mg ha-1, respectively. In the conversion to PA, 14.62 Mg ha-1 of CSt and 1.36 Mg ha-1 of NSt were lost in the 0–0.05 m layer. The area with PA had greater isotopic enrichment of δ13C in the layers of 0–0.05 and 0.05–0.10 m, with values of -18.3 and -17.4‰, respectively, while in the other layers the isotopic values decreased with the mixture between C of C3 and C4 plants. NV showed enrichment in the isotopic signals, in the layers from 0.25–0.30 m up to 0.40–0.45 m, with values between -21.74 and -21.54‰, respectively, which is characteristic of mixed vegetation of C3 and C4 plants. The values of δ15 N showed isotopic enrichment as depth increased, indicating greater mineralization of soil organic matter in both areas. The conversion of Cerrado into pasture and its consequent fragmentation causes negative impacts on the C and N sequestration and storage capacity, both in pasture and in natural vegetation
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