840 research outputs found
On Myosin II dynamics in the presence of external loads
We address the controversial hot question concerning the validity of the
loose coupling versus the lever-arm theories in the actomyosin dynamics by
re-interpreting and extending the phenomenological washboard potential model
proposed by some of us in a previous paper. In this new model a Brownian motion
harnessing thermal energy is assumed to co-exist with the deterministic swing
of the lever-arm, to yield an excellent fit of the set of data obtained by some
of us on the sliding of Myosin II heads on immobilized actin filaments under
various load conditions. Our theoretical arguments are complemented by accurate
numerical simulations, and the robustness of the model is tested via different
choices of parameters and potential profiles.Comment: 6 figures, 8 tables, to appear on Biosystem
Towards the Modeling of Neuronal Firing by Gaussian Processes
This paper focuses on the outline of some computational methods for the
approximate solution of the integral equations for the neuronal firing
probability density and an algorithm for the generation of sample-paths in
order to construct histograms estimating the firing densities. Our results
originate from the study of non-Markov stationary Gaussian neuronal models with
the aim to determine the neuron's firing probability density function. A
parallel algorithm has been implemented in order to simulate large numbers of
sample paths of Gaussian processes characterized by damped oscillatory
covariances in the presence of time dependent boundaries. The analysis based on
the simulation procedure provides an alternative research tool when closed-form
results or analytic evaluation of the neuronal firing densities are not
available.Comment: 10 pages, 3 figures, to be published in Scientiae Mathematicae
Japonica
Effect of organic matter release from natural cork used on bisphenol a removal from aqueous solution
The paper presents an experimental study aimed at investigating the mechanism responsible for Bisphenol A adsorption on natural cork, and the role played on process kinetics by the organic matter released from the cork. Obtained data show that natural cork has a good affinity toward Bisphenol A, with removal efficiency being as high as 75% in less than 24 h. The adsorption process is characterized by a fast-initial rate which tends to reduce progressively, and follows a pseudo second order model equation. Statistical physics analysis allows for obtaining a molecular description of the adsorption, which is shown to take place through a single anchorage point, perpendicularly to the adsorbent surface. Nuclear magnetic resonance spectroscopy and fluorescence analysis reveal that the colloidal organic matter released from the cork interacts with Bisphenol A; it also plays a relevant role in the slowing down of the adsorption rate, as it competes with cork adsorption sites for Bisphenol A. Organic matter is found to be highly heterogenous, presenting at the same time carbohydrates, aromatic and aliphatic domains. Such moieties interact stably with the contaminant in the solution probably due the establishment of dispersive forces (e.g. π-stacking) which sequestrate Bisphenol A into the inner hydrophobic core of the organic matter three-dimensional structure
Continuum and discrete approach in modeling biofilm development and structure: a review
The scientific community has recognized that almost 99% of the microbial life on earth is represented by biofilms. Considering the impacts of their sessile lifestyle on both natural and human activities, extensive experimental activity has been carried out to understand how biofilms grow and interact with the environment. Many mathematical models have also been developed to simulate and elucidate the main processes characterizing the biofilm growth. Two main mathematical approaches for biomass representation can be distinguished: continuum and discrete. This review is aimed at exploring the main characteristics of each approach. Continuum models can simulate the biofilm processes in a quantitative and deterministic way. However, they require a multidimensional formulation to take into account the biofilm spatial heterogeneity, which makes the models quite complicated, requiring significant computational effort. Discrete models are more recent and can represent the typical multidimensional structural heterogeneity of biofilm reflecting the experimental expectations, but they generate computational results including elements of randomness and introduce stochastic effects into the solutions
Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors
The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200 days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3) L H2/kgVSadded and 334.7 (±18.6) L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0–5.3) for the hydrogen producing bacteria
Mass loss controlled thermal pretreatment system to assess the effects of pretreatment temperature on organic matter solubilization and methane yield from food waste.
HIGHLIGHTS Direct correlation between substrate composition and TP effect was identified. The new experimental TP set-up minimized organic compound loss during TP of FW. The solubilization of carbohydrate and protein determined the optimal temperature of FW TP. Low temperature (80°C) TP attained the highest carbohydrate solubilization and methane yield. The effects of thermal pretreatment (TP) on the main characteristics of food waste (FW) and its biochemical methane potential (BMP) and distribution of volatile fatty acids (VFAs) under mesophilic condition (35°C) were investigated. The TP experiments were carried out at 80, 100, 120°C for 2 h and 140°C for 1 h. The designed TP set-up was able to minimize the organic matter loss during the course of the pretreatment. Soluble organic fractions evaluated in terms of chemical oxygen demand (COD) and soluble protein increased linearly with pretreatment temperature. In contrast, the carbohydrate solubilization was more enhanced (30% higher solubilization) by the TP at lower temperature (80°C). A slight increment of soluble phenols was found, particularly for temperatures exceeding 100°C. Thermally pretreated FW under all conditions exhibited an improved methane yield compared to the untreated FW, due to the increased organic matter solubilization. The highest cumulative methane yield of 442 (±8.6) mL/gVSadded, corresponding to a 28.1% enhancement compared to the untreated FW, was obtained with a TP at 80°C. No significant variation in the VFAs trends were observed during the BMP tests under all investigated conditions
Patient{'}s adherence on pharmacological therapy for benign prostatic hyperplasia (BPH)-associated lower urinary tract symptoms (LUTS) is different: Is combination therapy better than monotherapy
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An IoT-Aware Smart System Exploiting the Electromagnetic Behavior of UHF-RFID Tags to Improve Worker Safety in Outdoor Environments
Recently, different solutions leveraging Internet of Things (IoT) technologies have been adopted to avoid accidents in agricultural working environments. As an example, heavy vehicles, e.g., tractors or excavators, have been upgraded with remote controls. Nonetheless, the community continues to encourage discussions on safety issues. In this framework, a localization system installed on remote-controlled farm machines (RCFM) can help in preventing fatal accidents and reduce collision risks. This paper presents an innovative system that exploits passive UHF-RFID technology supported by commercial BLE Beacons for monitoring and preventing accidents that may occur when ground-workers in RCFM collaborate in outdoor agricultural working areas. To this aim, a modular architecture is proposed to locate workers, obstacles and machines and guarantees the security of RCFM movements by using specific notifications for ground-workers prompt interventions. Its main characteristics are presented with its main positioning features based on passive UHF-RFID technology. An experimental campaign discusses its performance and determines the best configuration of the UHF-RFID tags installed on workers and obstacles. Finally, system validation demonstrates the reliability of the main components and the usefulness of the proposed architecture for worker safety
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