Synthetizing hydrodynamic turbulence from noise: formalism and applications to plankton dynamics

We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian 2D turbulent flows by using linear stochastic partial differential equations, where the noise term acts as a random force of well-prescribed statistics. This methodology leads to a divergence-free, isotropic, stationary and homogeneous velocity field, whose characteristic parameters are well reproduced, in particular the kinematic viscosity and energy spectrum. This practical approach to tailor a turbulent flow is justified by its versatility when analizing different physical processes occurring in advectely mixed systems. Here, we focuss on an application to study the dynamics of Planktonic populations in the ocean

In vivo reconstitution of a homodimeric cytochrome b559 like structure: The role of the N-terminus a-subunit from Synechocystis sp. PCC 6803

The cytochrome b559 is a heme-bridged heterodimeric protein with two subunits, a and ß. Both subunits from Synechocystis sp. PCC 6803 have previously been cloned and overexpressed in Escherichia coli and in vivo reconstitution experiments have been carried out. The formation of homodimers in the bacterial membrane with endogenous heme was only observed in the case of the ß-subunit (ß/. ß) but not with the full length a-subunit. In the present work, reconstitution of a homodimer (a/. a) cytochrome b559 like structure was possible using a chimeric N-terminus a-subunit truncated before the amino acid isoleucine 17, eliminating completely a short amphipathic a-helix that lays on the surface of the membrane. Overexpression and in vivo reconstitution in the bacteria was clearly demonstrated by the brownish color of the culture pellet and the use of a commercial monoclonal antibody against the fusion protein carrier, the maltoside binding protein, and polyclonal antibodies against a synthetic peptide of the a-subunit from Thermosynechococcus elongatus. Moreover, a simple partial purification after membrane solubilization with Triton X-100 confirmed that the overexpressed protein complex corresponded with the maltoside binding protein-chimeric a-subunit cytochrome b559 like structure. The features of the new structure were determined by UV-Vis, electron paramagnetic resonance and redox potentiometric techniques. Ribbon representations of all possible structures are also shown to better understand the mechanism of the cytochrome b559 maturation in the bacterial cytoplasmic membrane

Noise-Induced Phase Separation: Mean-Field Results

We present a study of a phase-separation process induced by the presence of spatially-correlated multiplicative noise. We develop a mean-field approach suitable for conserved-order-parameter systems and use it to obtain the phase diagram of the model. Mean-field results are compared with numerical simulations of the complete model in two dimensions. Additionally, a comparison between the noise-driven dynamics of conserved and nonconserved systems is made at the level of the mean-field approximation.Comment: 12 pages (including 6 figures) LaTeX file. Submitted to Phys. Rev.

Phytotoxic potential of Lantana camara, Eucalyptus camaldulensis, Eriocephalus africanus, Cistus ladanifer and Artemisia gallica aqueous extracts to control weeds

[EN] Weed management is necessary in natural and agricultural ecosystems. The most used control method in developed countries has been the application of chemical herbicides, which has caused many problems in human health and the environment as well as the development of resistant weeds due to the repeated use of herbicides with the same mode of action. Natural products could be an alternative to synthetic herbicides for weed management. The society is demanding new solutions and research of bioherbicides has increased in the last years. Aqueous extracts from some plant species contain allelopathic compounds that can inhibit the germination and the development and growth of other plants or organisms. In this work the phytotoxic potential of aqueous extracts from Mediterranean plants are studied in order to find new solutions for integrated weed management.Verdeguer Sancho, MM.; Blazquez, M.; Boira Tortajada, H. (2018). Phytotoxic potential of Lantana camara, Eucalyptus camaldulensis, Eriocephalus africanus, Cistus ladanifer and Artemisia gallica aqueous extracts to control weeds. Journal of Allelochemical Interactions. 4(2):17-26. http://hdl.handle.net/10251/121086S17264

Comparative genomics, evolution, and drought-induced expression of dehydrin genes in model Brachypodium grasses

Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model Brachy-podium grass species. Due to limited knowledge on dehydrin expression under water deprivation stress in Brachypodium, we also performed a drought-induced gene expression analysis in 32 ecotypes of the genus’ flagship species B. distachyon showing different hydric requirements. Genomic sequence analysis detected 10 types of dehydrin genes (Bdhn) across the Brachypodium species. Domain and conserved motif contents of peptides encoded by Bdhn genes revealed eight protein architectures. Bdhn genes were spread across several chromosomes. Selection analysis indicated that all the Bdhn genes were constrained by purifying selection. Three upstream cis-regulatory motifs (BES1, MYB124, ZAT) were detected in several Bdhn genes. Gene expression analysis demonstrated that only four Bdhn1-Bdhn2, Bdhn3, and Bdhn7 genes, orthologs of wheat, barley, rice, sorghum, and maize genes, were expressed in mature leaves of B. distachyon and that all of them were more highly expressed in plants under drought conditions. Brachypodium dehydrin expression was significantly correlated with drought-response phenotypic traits (plant biomass, leaf carbon and proline contents and water use efficiency increases, and leaf water and nitrogen content decreases) being more pronounced in drought-tolerant ecotypes. Our results indicate that dehydrin type and regulation could be a key factor determining the acquisition of water-stress tolerance in grasses. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Entanglement of a Single Spin-1 Object: An Example of Ubiquitous Entanglement

Using a single spin-1 object as an example, we discuss a recent approach to quantum entanglement. The key idea of the approach consists in presetting of basic observables in the very definition of quantum system. Specification of basic observables defines the dynamic symmetry of the system. Entangled states of the system are then interpreted as states with maximal amount of uncertainty of all basic observables. The approach gives purely physical picture of entanglement. In particular, it separates principle physical properties of entanglement from inessential. Within the model example under consideration, we show relativity of entanglement with respect to dynamic symmetry and argue existence of single-particle entanglement. A number of physical examples are considered.Comment: 12 pages, 2 figure : title has been changed, paper is re-organized, new section "Violation of Bell-type condition by single spin-1" is adde

Application of Problem-Based Learning (PBL) in the Course "Industrial Chemical Technology" of the Master's Degree in Industrial Engineering

[EN] This paper describes the application of Problem-Based Learning (PBL) in the subject "Industrial Chemical Technology" of the Master's Degree in Industrial Engineering from the Universitat Politécnica de València (UPV). This course includes contents related to the Basic Operations of Chemical Engineering, not previously studied by most students. This fact, together with the difficulties associated with the management of 300 students have conditioned the type of methodologies that can be applied and, therefore, the level of depth at which the contents can be developed. Therefore, the main methodology applied so far has been the participative masterclass, with problem solving in the classroom. Although the results in terms of percentage of students who pass the course are very satisfactory, the approach to learning is superficial in some aspects and teachers believe that it should be adapted to master's level. To achieve deeper learning of students in the contents of the course, it has been decided to partially modify the methodology, integrating Problem-Based Learning (ABP). This new methodology will consist of grouped resolution of problems integrated into the same real industrial process, which will allow students to also acquire a more global view of the contents covered in the course. The level of the problems will be increased compared to those solved in the classroom and students will be required to search, select and justify additional data and information to solve the problems that will also be multidisciplinary. All this innovation is part of an Innovation and Educational Improvement Project granted and funded by the ¿Vicerrectorado de Estudios, Calidad y Acreditación (VECA)¿ of the UPV. This work describes how the PBL has been defined for implementation in the course and analyses the results achieved to date, identifying the aspects to be improved for the continuation of the methodology in the following academic years.This work has been funded by the Vicerrectorado de Estudios, Calidad y Acreditación (VECA of the Universitat Politécnica València (A + D Call for Innovation and Educational Improvement Projects)Sancho, M.; García-Fayos, B.; Garcia-Castello, EM.; Martí Calatayud, MC.; Rodríguez López, AD.; Bes-Piá, M.; Mendoza Roca, JA.... (2021). Application of Problem-Based Learning (PBL) in the Course "Industrial Chemical Technology" of the Master's Degree in Industrial Engineering. IATED. 3740-3747. https://doi.org/10.21125/inted.2021.0775S3740374

Mean first passage times of processes driven by white shot noise

The systems driven by white shot noise are analyzed based on mean first passage times. The shot noise has exponentially distributed jump heights. The the linkage between the results and the steady state probability density function of the process are presented

A first-principles approach to electrical transport in atomic-scale nanostructures

We present a first-principles numerical implementation of Landauer formalism for electrical transport in nanostructures characterized down to the atomic level. The novelty and interest of our method lies essentially on two facts. First of all, it makes use of the versatile Gaussian98 code, which is widely used within the quantum chemistry community. Secondly, it incorporates the semi-infinite electrodes in a very generic and efficient way by means of Bethe lattices. We name this method the Gaussian Embedded Cluster Method (GECM). In order to make contact with other proposed implementations, we illustrate our technique by calculating the conductance in some well-studied systems such as metallic (Al and Au) nanocontacts and C-atom chains connected to metallic (Al and Au) electrodes. In the case of Al nanocontacts the conductance turns out to be quite dependent on the detailed atomic arrangement. On the contrary, the conductance in Au nanocontacts presents quite universal features. In the case of C chains, where the self-consistency guarantees the local charge transfer and the correct alignment of the molecular and electrode levels, we find that the conductance oscillates with the number of atoms in the chain regardless of the type of electrode. However, for short chains and Al electrodes the even-odd periodicity is reversed at equilibrium bond distances.Comment: 14 pages, two-column format, submitted to PR