Doubly-periodic array of bubbles in a Hele-Shaw cell

Exact solutions are presented for a doubly-periodic array of steadily moving bubbles in a Hele-Shaw cell when surface tension is neglected. It is assumed that the bubbles either are symmetrical with respect to the channel centreline or have fore-and-aft symmetry, or both, so that the relevant flow domain can be reduced to a simply connected region. By using conformal mapping techniques, a general solution with any number of bubbles per unit cell is obtained in integral form. Several examples are given, including solutions for multi-file arrays of bubbles in the channel geometry and doubly-periodic solutions in an unbounded cell.Comment: 15 pages, 12 figure

Pengukuran Tingkat Kesadaran Merek (Brand Awareness) pada Motor Honda (Studi Kasus pada Mahasiswa Fakultas Ilmu Sosia dan Ilmu Politik Universitas Riau)

This study was conducted to test the Brand Awareness Level Measurement (Brand Awareness) At Honda Motor (Case study of social, Faculty of Science and Political Science, University of Riau). Brand awareness measurement can be done by characterizing the four elements, namely, top of mind, brand recall, brand recognition, unaware of the brand. The sampling method used is convenience sampling that samples can be found easily, as many as 100 respondents.Analysis technique used is descriptive analysis, which can be interpreted as the troubleshooting procedures that are surrounded by depict or describe the circumstances, the subject or object of research at the present time based on the facts that appear or as it is. Data are presented in tabular form with the numbers percentage delengkapi with descriptions.From the calculation of the analysis we found that the motorcycle brand Honda took first place by 58% of respondents, brand recall brand motorcycle Honda finished second at 25%, the brand recognition of 80% indicating so familiar brands of motorcycles honda among consumers, the analysis unaware of brand honda motorcycle brands are not categorized within unaware of the brand for the majority of respondents know the brands of motorbikes honda

Structural basis for membrane insertion by the human ER membrane protein complex

A defining step in the biogenesis of a membrane protein is the insertion of its hydrophobic transmembrane helices into the lipid bilayer. The nine-subunit endoplasmic reticulum (ER) membrane protein complex (EMC) is a conserved co- and posttranslational insertase at the ER. We determined the structure of the human EMC in a lipid nanodisc to an overall resolution of 3.4 angstroms by cryo–electron microscopy, permitting building of a nearly complete atomic model. We used structure-guided mutagenesis to demonstrate that substrate insertion requires a methionine-rich cytosolic loop and occurs via an enclosed hydrophilic vestibule within the membrane formed by the subunits EMC3 and EMC6. We propose that the EMC uses local membrane thinning and a positively charged patch to decrease the energetic barrier for insertion into the bilayer

Four-vortex motion around a circular cylinder

The motion of two pairs of counter-rotating point vortices placed in a uniform flow past a circular cylinder is studied analytically and numerically. When the dynamics is restricted to the symmetric subspace---a case that can be realized experimentally by placing a splitter plate in the center plane---, it is found that there is a family of linearly stable equilibria for same-signed vortex pairs. The nonlinear dynamics in the symmetric subspace is investigated and several types of orbits are presented. The analysis reported here provides new insights and reveals novel features of this four-vortex system, such as the fact that there is no equilibrium for two pairs of vortices of opposite signs on the opposite sides of the cylinder. (It is argued that such equilibria might exist for vortex flows past a cylinder confined in a channel.) In addition, a new family of opposite-signed equilibria on the normal line is reported. The stability analysis for antisymmetric perturbations is also carried out and it shows that all equilibria are unstable in this case.Comment: 27 pages, 13 figures, to be published in Physics of Fluid

First report of Rice stripe necrosis virus infecting rice in Sierra Leone

While Rice stripe necrosis virus (RSNV, Benyvirus, Benyviridae) has been reported on rice plants on two continents, little is known about the diversity of this multipartite virus which is transmitted by the plasmodiophorid protist Polymyxa graminis. First identified in 1983 in the Côte d´Ivoire (Fauquet & Thouvenel, 1983), the disease had previously been observed in Sierra Leone without formal identification of the causal agent (Buddenhagen, pers. comm.). Later, the virus was reported in South and Central America (Colombia, Ecuador, Panama and Brazil) causing up to 40% yield losses (Morales et al., 1999). Recently, RSNV was identified for the first time in several African countries including Burkina Faso (Sérémé et al., 2014), Benin (Oludare et al., 2015) and Mali (Decroës et al., 2017) suggesting a re-emergence of the virus in Africa.In 2019, symptoms of leaf-crinkling and stripe necrosis were observed on a rice plant from the Bo District in Sierra Leone (Fig. 1). Leaf samples were analysed by serological and molecular methods to confirm the presence of RSNV in Sierra Leone. RSNV was detected by plate-trapped antibody (PTA)- ELISA using a polyclonal antiserum against RSNV (Fauquet & Thouvenel, 1983).The presence of the virus was confirmed after total RNA extraction using 0.05 g of leaves and the RNeasy Plant Mini Kit (Qiagen) and RT-PCR amplification (10 U/μl M-MLV-reverse transcriptase, Promega; 10 U/μl Dynazyme, Finnzyme) as described previously (Sérémé et al., 2014, Oludare et al., 2015) with primers RSNV1-2901F 5′-TGAATTTGGTGCTCTCTTG-3′ / RSNV1-3827R 5′-TGTGGCGTTTCCAGACCTAAA-3´ and RSNV2-5´ 5´-TATCACTACTGACGAATTCCACCTAC-3´ / RSNV2-1223R 5´-AATCTGCGGCCTGTTTTGTA-3´. Specific amplicons, 926 and 1241 nt in length, were generated corresponding to sequences in the helicase domain and the coat protein (CP) genes on RSNV RNA 1 and RNA 2, respectively. The amplicons were sequenced directly and the sequences deposited in GenBank (Accession Nos. MN750254 and MN750255, respectively).The helicase sequence obtained from the Sierra Leone RSNV isolate showed 1.8-7.3% genetic distance with those from South America (EU099844.3, MG792544, MG792545, MG792546) and only 1.4-2.2% with those from Africa (KP099623, MF115599, MF115600, MF115601, MF115602, MF115603, MK170452, MK170453). The phylogenetic analysis based on the helicase domain included the sequence obtained from the Sierra Leone within a cluster represented by RSNV from South America and West Africa (Fig. 2a). In contrast, the CP sequence from the Sierra Leone RSNV isolate revealed an unexpected genetic differentiation as compared to all the other sequences from South America (5.6%; NC_038774) or Africa (5.2-6.5%; LK023710, MF115604, MF115605, MF115606, MF115607, MF115608, MK170454, MK170455). Interestingly, the CP sequence from Sierra Leone is located at a basal position in the phylogeny (Fig. 2b).To our knowledge, this is the first confirmed report of RSNV in Sierra Leone. Further studies are needed to assess the molecular and biological diversity of RSNV, the spatial distribution and the incidence of this re-emerging rice disease in Africa.Fil: Tucker, M. J.. Sierra Leone Agricultural Research Institute; Sierra LeonaFil: Giovani Celli, Marcos Giovani. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; ArgentinaFil: Conteh, A. B.. Sierra Leone Agricultural Research Institute; Sierra LeonaFil: Taylor, D. R.. Sierra Leone Agricultural Research Institute; Sierra LeonaFil: Hebrard, Andrés. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; FranciaFil: Poulicard, N.. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Franci

Awareness of children about rational use of water: an approach basing on serious game

The water shortage expectation in a near future proves that the worldpopulation must be mobilized, as soon as possible, to face the problem of the water waste in daily activities. This paper presents the development of a web serious game to teach children about that problem which already affecting lives of many people around the world. We believe that education could be the better tool to change cultural habits and, in this way, the bigger awareness and a better use of hydric resources

Low-Cost Potentiometric Sensor for Chloride Measurement in Continuous Industrial Process Control

Recently, the new updates in legislation about drinking water control and human health have increased the demand for novel electrochemical low-cost sensors, such as potentiometric ones. Nowadays, the determination of chloride ion in aqueous solutions has attracted great attention in several fields, from industrial processes to drinking water control. Indeed, chloride plays a crucial role in corrosion, also influencing the final taste of beverages, especially coffee. The main goal is to obtain devices suitable for continuous and real-time analysis. For these reasons, we investigated the possibility to develop an easy, low-cost potentiometric chloride sensor, able to perform analysis in aqueous mediums for long immersion time and reducing the need of periodic calibration. We realized a chloride ion selective electrode made of Ag/AgCl sintered pellet and we tested its response in model solutions compatible with drinking water. The sensor was able to produce a stable, reproducible, and accurate quantification of chloride in 900 s, without the need for a preliminary calibration test. This opens the route to potential applications of this sensor in continuous, in situ, and real time measurement of chloride ions in industrial processes, with a reduced need for periodic maintenance