Propagation of capillary waves in two-layer oil-water turbulent flow

We study the dynamics of capillary waves at the interface of a two-layer stratified turbulent channel flow. We use a combined pseudo-spectral/phase field method to solve for the turbulent flow in the two liquid layers and to track the dynamics of the liquid-liquid interface. The two liquid layers have same thickness and same density, but different viscosity. We vary the viscosity of the upper layer (two different values) to mimic a stratified oil-water flow. This allows us to study the interplay between inertial, viscous and surface tension forces in the absence of gravity. In the present set-up, waves are naturally forced by turbulence over a broad range of scales, from the larger scales, whose size is of order of the system scale, down to the smaller dissipative scales. After an initial transient, we observe the emergence of a stationary capillary wave regime, which we study by means of temporal and spatial spectra. The computed frequency and wavenumber power spectra of wave elevation are in line with previous experimental findings and can be explained in the frame of the weak wave turbulence theory. Finally, we show that the dispersion relation, which gives the frequency as a function of the wavenumber , is in good agreement with the well-established theoretical prediction,

Clinical validation results of an innovative non-invasive device for colorectal cancer preventive screening through fecal exhalation analysis

Screening is recommended to reduce both incidence and mortality of colorectal cancer. Currently, many countries employ fecal occult blood test (FOBT). In Emilia-Romagna (Italy), since 2005, FOBT immunochemical version (FIT) is performed every two years on people aged between 50 and 69 years. A colonoscopy is then carried out on those who are FIT positive. However, FIT shows approximately 65% false positives (non-tumoral bleedings), leading to many negative colonoscopies. The use of an economic and easy-to-use method to check FOBT-positives will improve screening effectiveness, reducing costs to the national health service. This work illustrates the results of a three-year clinical validation protocol (started in 2016) of a patented device composed of a core of nanostructured gas sensors. This device was designed to identify CRC presence by fecal volatile compounds, with a non-invasive, in vitro and low-cost analysis. Feces are, in fact, affected by tumor-volatile biomarkers, produced by cellular peroxidation and metabolic alterations. The protocol consisted in the analysis of fecal samples of FIT-positive subjects, using colonoscopy as a gold standard. A total of 398 samples were analyzed with machine learning techniques, leading to a sensitivity and specificity of 84.1% and 82.4%, respectively, and a positive predictive value of 72% (25–35% for FIT)

Devices for Screening and Monitoring of Tumors Based on Chemoresistive Sensors

Abstract In this work two devices are presented, named SCENT A1 (A1) and SCENT B1 (B1), composed of chemoresistive sensors. Such devices are capable of discriminating the different compositions of gas mixtures emitted by stools, for colorectal cancer screening (A1), and by blood, for tumors monitoring (B1), according to defined sampling protocols. Results have been acquired by a LabView® software and statistically treated (e.g. quadratic discriminant analysis, QDA) and show to be encouraging with an error of 5% for SCENT A1. Preliminary results of SCENT B1 proved to be promising. Further studies will be carried out for clinically validating the two devices

On the size of knots in ring polymers

We give two different, statistically consistent definitions of the length l of a prime knot tied into a polymer ring. In the good solvent regime the polymer is modelled by a self avoiding polygon of N steps on cubic lattice and l is the number of steps over which the knot ``spreads'' in a given configuration. An analysis of extensive Monte Carlo data in equilibrium shows that the probability distribution of l as a function of N obeys a scaling of the form p(l,N) ~ l^(-c) f(l/N^D), with c ~ 1.25 and D ~ 1. Both D and c could be independent of knot type. As a consequence, the knot is weakly localized, i.e. ~ N^t, with t=2-c ~ 0.75. For a ring with fixed knot type, weak localization implies the existence of a peculiar characteristic length l^(nu) ~ N^(t nu). In the scaling ~ N^(nu) (nu ~0.58) of the radius of gyration of the whole ring, this length determines a leading power law correction which is much stronger than that found in the case of unrestricted topology. The existence of such correction is confirmed by an analysis of extensive Monte Carlo data for the radius of gyration. The collapsed regime is studied by introducing in the model sufficiently strong attractive interactions for nearest neighbor sites visited by the self-avoiding polygon. In this regime knot length determinations can be based on the entropic competition between two knotted loops separated by a slip link. These measurements enable us to conclude that each knot is delocalized (t ~ 1).Comment: 29 pages, 14 figure

Introduction : translingual work.

This issue both reflects and builds on the efforts prompted by the 2011 College English essay “Language Difference in Writing: Toward a Translingual Approach,” by Bruce Horner, Min-Zhan Lu, Jacqueline Jones Royster, and John Trimbur. Contributions to this symposium contextualize the emergence of a translingual approach, explore the tension and interconnections between a translingual approach and a variety of fields, and explore the viability of a translingual approach in light of existing academic structures

Chemoresistive Gas Sensor based on SiC Thick Film: Possible Distinctive Sensing Properties Between H2S and SO2☆

Commercially available nanosized powder of silicon carbide (named SiC), was thermally, morphologically and structurally characterized. After that, it was screen-printed onto alumina substrates in order to obtain thick films to be tested as functional material for conductometric gas sensors. Samples were exposed to SO2 and H2S, gases with high importance in many application fields, with the aim of verifying its capability of distinguishing between them. The characterization highlighted that this semiconductor type is selective for sulphur dioxide (SO2), in concentrations within the ppm range. This interesting result was found at high temperatures (600-800°C), useful for harsh environmental, and the measurements proved to be completely free from humidity interference. Applications of such a sensor could span many fields, since SO2 plays an important role in air pollution, industrial processes and wine making monitoring

Alterações morfológicas e qualidade fisiológica de sementes de mamão.

A análise de raios X é uma técnica importante na identificação de problemas associados à morfologia interna de sementes e ao seu potencial fisiológico. O objetivo do estudo foi avaliar os padrões morfológicos e a qualidade fisiológica de sementes de mamão obtidas de diferentes estádios de maturação e locais dentro do fruto com o auxílio das análises de raios X. Foram utilizadas sementes de mamão Formosa colhidos no estádio 1 de maturação. As sementes foram extraídas dos frutos nos estádios 1, 3, 5 e final. Os frutos foram armazenados em condições de laboratório (25 °C) e ao atingirem cada estádio de maturação, foram seccionados transversalmente em três partes de tamanhos iguais, sendo as sementes das duas extremidades (proximal e distal) extraídas separadamente daquelas localizadas na região central. Depois de lavadas e secas, as sementes foram utilizadas nas seguintes avaliações: 1) teste de germinação em papel germitest umedecido com água destilada em temperatura alternada 20-30°C. Avaliou-se a velocidade de germinação, plântulas normais na primeira contagem e as porcentagens de germinação, sementes dormentes e sementes inviáveis aos 30 dias; e, 2) teste de raios X, determinando-se as porcentagens de sementes cujo embrião era facilmente visível, com radícula visível e sementes aparentemente vazias. O experimento foi conduzido em delineamento inteiramente casualizado, em fatorial (duas regiões do fruto e quatro estádios de maturação) em quatro repetições. As médias comparadas pelo teste de Tukey a 5% de probabilidade. Constatou-se que sementes localizadas na parte central dos frutos apresentaram desempenho superior às sementes das extremidades. O estádio 1 de maturação apresentou número de sementes vazias e dormentes superior aos demais estádios. O teste de raios X favoreceu a diferenciação entre sementes de mamão vazias e com embrião completamente desenvolvido.Resum