Liquid recirculation in microfluidic channels by the interplay of capillary and centrifugal forces

We demonstrate a technique to recirculate liquids in a microfluidic device, maintaining a thin fluid layer such that typical diffusion times for analytes to reach the device surface are < 1 min. Fluids can be recirculated at least 1000 times across the same surface region, with no change other than slight evaporation, by alternating the predominance of centrifugal and capillary forces. Mounted on a rotational platform, the device consists of two hydrophilic layers separated by a thin pressure-sensitive adhesive (PSA) layer that defines the microfluidic structure. We demonstrate rapid, effective fluid mixing with this device

Thin film diffusion barrier formation in PDMS microcavities

We describe a method to form glass like thin film barrier in polydimethylsiloxane (PDMS) microcavities. The reactive fragments for the surface reaction were created from O2 and hexamethyldisiloxane (HMDS) in RF plasma environment. The reaction is based on migration of the reactive fragments into the microcavities by diffusion, to form a glass like thin film barrier to conceal the naked surface of PDMS. The barrier successfully blocked penetration of a fluorescent dye rhodamine B (RhB) into PDMS. The thickness of the barrier could be controlled by the time of reaction and the pressure inside the reaction chamber. There is a wide range of applications of such a technique in various fields, e.g. for coating the covered surfaces of microfluidic channels, tubes, capillaries, medical devices, catheters, as well as chip-integrated capillary electrophoresis and advanced electronic and opto-fluidic packaging

Model validation for a noninvasive arterial stenosis detection problem

Copyright @ 2013 American Institute of Mathematical SciencesA current thrust in medical research is the development of a non-invasive method for detection, localization, and characterization of an arterial stenosis (a blockage or partial blockage in an artery). A method has been proposed to detect shear waves in the chest cavity which have been generated by disturbances in the blood flow resulting from a stenosis. In order to develop this methodology further, we use both one-dimensional pressure and shear wave experimental data from novel acoustic phantoms to validate corresponding viscoelastic mathematical models, which were developed in a concept paper [8] and refined herein. We estimate model parameters which give a good fit (in a sense to be precisely defined) to the experimental data, and use asymptotic error theory to provide confidence intervals for parameter estimates. Finally, since a robust error model is necessary for accurate parameter estimates and confidence analysis, we include a comparison of absolute and relative models for measurement error.The National Institute of Allergy and Infectious Diseases, the Air Force Office of Scientific Research, the Deopartment of Education and the Engineering and Physical Sciences Research Council (EPSRC)

Kama muta: conceptualizing and measuring the experience of being moved across 19 nations and 15 languages

English-speakers sometimes say that they feel moved to tears, emotionally touched, stirred, or that something warmed their heart; other languages use similar passive contact metaphors to refer to an affective state. We propose and measure the concept of kama muta to understand experiences often given these and other labels. Do the same experiences evoke the same kama muta emotion across nations and languages? We conducted studies in 19 different countries, five continents, 15 languages, with a total of 3542 participants. We tested the construct while validating a comprehensive scale to measure the appraisals, valence, bodily sensations, motivation, and lexical labels posited to characterize kama muta. Our results are congruent with theory and previous findings showing that kama muta is a distinct positive social relational emotion that is evoked by experiencing or observing a sudden intensification of communal sharing. It is commonly accompanied by a warm feeling in the chest, moist eyes or tears, chills or piloerection, feeling choked up or having a lump in the throat, buoyancy and exhilaration. It motivates affective devotion and moral commitment to communal sharing. While we observed some variations across cultures, these five facets of kama muta are highly correlated in every sample, supporting the validity of the construct and the measure.info:eu-repo/semantics/acceptedVersio

National culture and tourist destination choice in the UK and Venezuela: an exploratory and preliminary study

National culture determines consumer attitudes and behaviour. While this holds true for tourism consumption, little research has sought to better understand the effect of culture on tourist destination choice. The geographical scope of analysis has also been restricted. This study employs the Hofstede’s cultural dimensions framework to conduct an exploratory, qualitative evaluation of the influence of the tourist cultural background on destination choice. It focuses on the UK and Venezuela, the two countries with significant cultural differences and forecast growth in outbound tourism. The study shows the distinct role of culture in tourist preferences for destination choice and structure of travel groups. The effect of culture is also recorded in how tourists research destinations prior to visit and perceive travel risks, thus ultimately influencing their motivation to travel. Recommendations are developed on how to integrate knowledge on the cultural background of tourists into tourism management and policy-making practices

Ancient DNA from Hunter-Gatherer and Farmer Groups from Northern Spain Supports a Random Dispersion Model for the Neolithic Expansion into Europe

Background/Principal Findings: The phenomenon of Neolithisation refers to the transition of prehistoric populations from a hunter-gatherer to an agro-pastoralist lifestyle. Traditionally, the spread of an agro-pastoralist economy into Europe has been framed within a dichotomy based either on an acculturation phenomenon or on a demic diffusion. However, the nature and speed of this transition is a matter of continuing scientific debate in archaeology, anthropology, and human population genetics. In the present study, we have analyzed the mitochondrial DNA diversity in hunter-gatherers and first farmers from Northern Spain, in relation to the debate surrounding the phenomenon of Neolithisation in Europe. Methodology/Significance: Analysis of mitochondrial DNA was carried out on 54 individuals from Upper Paleolithic and Early Neolithic, which were recovered from nine archaeological sites from Northern Spain (Basque Country, Navarre and Cantabria). In addition, to take all necessary precautions to avoid contamination, different authentication criteria were applied in this study, including: DNA quantification, cloning, duplication (51 % of the samples) and replication of the results (43 % of the samples) by two independent laboratories. Statistical and multivariate analyses of the mitochondrial variability suggest that the genetic influence of Neolithisation did not spread uniformly throughout Europe, producing heterogeneous genetic consequences in different geographical regions, rejecting the traditional models that explain the Neolithisation in Europe

Judicial disagreement need not be political: dissent on the Estonian Supreme Court

I investigate the non-unanimous decisions of judges on the Estonian Supreme Court. I argue that since judges on the court enjoy high de jure independence, dissent frequently, and are integrated in the normal judicial hierarchy, the Estonian Supreme Court is a crucial case for the presumption that judicial disagreement reveals policy preferences. I analyse dissenting opinions using an ideal point response model. Examining the characteristics of cases which discriminated with respect to the recovered dimension, I show that this dimension cannot be interpreted as a meaningful policy dimension, but instead reflects disagreement about the proper scope of constitutional redress

HDG-NEFEM with Degree Adaptivity for Stokes Flows

This paper presents the first degree adaptive procedure able to directly use the geometry given by a CAD model. The technique uses a hybridisable discontinuous Galerkin discretisation combined with a NURBS-enhanced rationale, completely removing the uncertainty induced by a polynomial approximation of curved boundaries that is common within an isoparametric approach. The technique is compared against two strategies to perform degree adaptivity currently in use. This paper demonstrates, for the first time, that the most extended technique for degree adaptivity can easily lead to a non-reliable error estimator if no communication with CAD software is introduced whereas if the communication with the CAD is done, it results in a substantial computing time. The proposed technique encapsulates the CAD model in the simulation and is able to produce reliable error estimators irrespectively of the initial mesh used to start the adaptive process. Several numerical examples confirm the findings and demonstrate the superiority of the proposed technique. The paper also proposes a novel idea to test the implementation of high-order solvers where different degrees of approximation are used in different elements