Material transport in the left ventricle with aortic valve regurgitation

This experimental in vitro work investigates material transport properties in a model left ventricle in the case of aortic regurgitation, a valvular disease characterized by a leaking aortic valve and consequently double-jet filling within the elastic left ventricular geometry. This study suggests that material transport phenomena are strongly determined by the motion of the counterrotating vortices driven by the regurgitant aortic and mitral jets. The overall particle residence time appears to be significantly longer with moderate aortic regurgitation, attributed to the dynamics resulting from the timing between the onset of the two jets. Increasing regurgitation severity is shown to be associated with higher frequencies in the time-frequency spectra of the velocity signals at various points in the flow, suggesting nonlaminar mixing past moderate regurgitation. Additionally, a large part of the regurgitant inflow is retained for at least one cardiac cycle. Such an increase in particle residence time accompanied by the occurrence and persistence of a number of attracting Lagrangian coherent structures presents favorable conditions and locations for activated platelets to agglomerate within the left ventricle, potentially posing an additional risk factor for patients with aortic regurgitation

Sedimentological, Mineralogical and Geochemical Studies of Holocene Coastal Sediments, South-Western Scotland

Holocene raised coastal sediments of the Dalbeattie, Kirkcudbright and New Abbey areas in Galloway, and the area of the former Lochar Gulf in Dumfriesshire, together with present-day intertidal surface sediments from the first three of these areas, were studied. In Part I, the nature of the research project and previous related work is considered. A summary of the geological setting of the field areas is also given. The first half of Part II is concerned with the methods used in data-recording and sample collection in the field and with stratigraphical correlation of the Holocene raised coastal sediments within the Dalbeattie, Kirkcudbright and New Abbey areas on the basis of exposed vertical sections and auger-drilled boreholes. Correlation of the sedimentary sequences recorded in these sections and boreholes suggests that several sedimentary facies can be distinguished in the three areas studied in this way. Four sedimentary facies are also recognised within the present-day intertidal deposits of the same areas. Following a discussion of the concept of sedimentary facies, previous recognition of such facies in SW Scotland and the criteria on which sedimentary facies were distinguished in the course of the research project, descriptions of the present-day and Holocene facies are given. The four sedimentary facies recognised within the present-day intertidal deposits are: tidal-flat; tidal-creek; salt marsh; sand-barrier. The seven sedimentary facies recognised within the Holocene sediments are: A, complex of fine-grained sediments; B, inter-laminated fine sand and silt; C, coarse sand with pebbles; D, fine sand, rich in microfaunal remains; E, clays, rich in plant debris; F, coastal gravel and sand; G, peat. In Part III, data on the shapes, sphericity, roundness and lithological compositions of Pleistocene glaciofluvial and Holocene storm-beach gravel deposits in the Dalbeattie area are presented and compared. Pleistocene clasts are mainly discs, Holocene clasts mainly blades; sphericity ranges between 0.5 and 0.9 in both cases, but the degree of roundness is greater in the Holocene clasts than in the Pleistocene. Greywacke is the commonest rock type in both. The Pleistocene gravels probably were derived mainly from the NW and west, the Holocene gravels partly from the Criffell-Dalbeattie granodioritic pluton and partly from Pleistocene glaciofluvial deposits. The results of orientation studies of (mainly) Holocene gravel clasts in the Dalbeattie and New Abbey areas are also given. They suggest deposition by SE-NW water flow. Detailed grain-size analysis indicates that most of the Holocene sediments in the Dalbeattie area and in the upper part of the successions in the Kirkcudbright and New Abbey areas (sediments of facies A) are of silt grade and bimodal or polymodal in grain-size distribution, whereas sand-grade and unimodal grain-size distribution predominate in the Holocene sediments (of facies D) in the area of the former Lochar Gulf and in the lower part of the succession in the Kirkcudbright and New Abbey areas. The present-day intertidal sediments of the Dalbeattie, Kirkcudbright and New Abbey areas are mainly of fine-sand grade and unimodal in grain-size distribution. In descending order of abundance, illite (mainly with the composition of biotite and muscovite), chlorite (mainly Fe-chlorite), kaolinite and vermiculite are the main clay minerals present in both the present-day intertidal and Holocene raised coastal sediments in the areas studied. Both detrital and authigenic illite, chlorite and kaolinite are present; detrital material greatly predominates over authigenic material in the cases of chlorite and kaolinite. Vermiculite is more abundant in the uppermost facies, A, than in the various underlying facies. Mixed-layer clays and montmorillonite are present in minor amounts in the Holocene sediments. Geochemical analysis of bulk samples and samples of the clay fraction of both the Holocene and present-day sediments indicates that the SiO2 content, which is inversely related to the content of Al2O3, total iron, TiO2, MgO and K2O, is higher in the Holocene sediments of the Lochar Gulf area than in the sediments of the same age in the three other areas studied. The CaO content in Holocene sedimentary facies D, which is approximately equal to that in the present-day sediments and higher than in the other Holocene sediments, may have been derived from fossil shell and other organic carbonate fragments in facies D. The trace elements Y, Sr, Rb, Th, Pb, Zn, Ni, Co, Ce, Cr, Ba and La are associated with the clay minerals present in the sediments. Environments of deposition and possible provenances of the Holocene sediments are discussed in Part IV

Note on transport equation and fractional Sumudu transform.

In this paper, the Chebyshev polynomials to solve analytically the fractional neutron transport equation in one-dimensional plane geometry are used. The procedure is based on the expansion of the angular flux in terms of the Chebyshev polynomials. The obtained system of fractional linear differential equation is solved analytically by using fractional Sumudu transform

A Comparative Study of Shehu Variational Iteration Method and Shehu Decomposition Method for Solving Nonlinear Caputo Time-Fractional Wave-like Equations with Variable Coefficients

In this paper, a comparative study between two different methods for solving nonlinear Caputo time-fractional wave-like equations with variable coefficients is conducted. These two methods are called the Shehu variational iteration method (SVIM) and the Shehu decomposition method (SDM). To illustrate the efficiency and accuracy of the proposed methods, three different numerical examples are presented. The results obtained show that the two methods are powerful and efficient methods which both give approximations of higher accuracy and closed form solutions if existing. However, the SVIM has an advantage over SDM that it solves the nonlinear problems without using the Adomian polynomials. Furthermore, the SVIM enables us to overcome the difficulties arising in identifying the general Lagrange multiplier and it may be considered as an added advantage of this technique over the SDM

Organic solar cells: study of combined effects of active layer nanostructure and electron and hole transport layers

An organic solar cell based on Poly (3-hexathiophine-2,5-diyl) and [6,6]-Phenyl C61 butyric acid methyl ester has been subjected to all layers treatment and was investigated for combined effects of the these layers on device performance. These treatment included optimization of active layer morphology and thickness and improving the structure of the hole and electron transport layers, as well as subjecting the full device to optimum post deposition thermal treatment. Such a device has shown an increase in the optical absorption intensity in the near infrared region compared to the reference device, which is thought to be advantageous for producing high current density. The increase in the current density has also been correlated with light trapping within the active layer and the possibility of the occurrence of total internal reflection, which was explained using total internal reflection spectroscopic ellipsometry measurements. The current density-voltage characteristics have been measured in dark and under illumination. Power conversion efficiency as high as 7% has been achieved correlated with a fill factor of 71%

Pearls and Perils of Pupillometry Using a Webcam

Current methods to measure infants’ cognitive repertoire (i.e., collection of cognitive abilities) are limited. Previous testing paradigms required acquisition of non-age contextualized responses, and relied on measures that involved acquisition of other functions (e.g., language, motor). In addition to response limitations, cognitive functions may be difficult to observe in infants due to the difficulty in infant recruitment. Online testing has increased infant recruitment efforts and physiological responses have bypassed the motor, behavioural and linguistic limitations of infants. Recently, it has been shown that heart rate measures can be acquired through a webcam. Another feasible and reliable physiological measure is pupillometery, the measure of pupil diameter, whereby an increase in pupil diameter corresponds to an increase in cognitive load in response to meaningful stimuli in our environment. Through successive pilot studies over an online interface (i.e., Mturk), we optimized the participants imaging environment. We show that acquisition of pupil diameter is possible over Mturk using our in-house methods. Moreover, we validated our measurement methods as a reliable tool for measuring cognitive load in adults, and as a future means of characterizing cognitive activation in infants. To our knowledge, we are the first to acquire pupil diameter measures through an online interface. The methodologies developed herein can be used as a valid means for acquiring physiological responses in future studies investigating cognition, attention, and memory thereby overcoming current limitations in both acquisition of responses and participant recruitment of infants

The Effect of Fullerene Derivatives Ratio on P3HT-based Organic Solar Cells

The effect of fullerene ratio PCBM and ICBA on the P3HT-based solar cells were investigated under ambient conditions; the ratio was varied in the range of 1-3. The optical, morphological, structural, and electrical characteristics were investigated both in dark and under illumination. The absorption spectra have revealed a decrease in the intensities by increasing the fullerene ratio and the peaks were blue shifted. Moreover, florescence spectra demonstrated charge transfer from P3HT to fullerene molecules due to uniform distribution of fullerene domains within the P3HT matrix. XRD patterns have shown a strong reduction in the crystallinity by increasing the ratio of fullerene within the blend. Furthermore, AFM images showed smother surface corresponding to pinholes with higher ratio while rougher surface with lower fullerene ratio was observed. The best performance was recorded for P3HT:PCBM (3:1) with VOC = 0.58 volt, JSC = 9.9 mA.cm-2 and PCE 1.82%. The fill factor (FF) was found to be small for all studied samples which could be associated with the preparation conditions where all samples were prepared under normal ambient. Devices which demonstrated best performance were attributed to improved crystallinity and enhanced light absorption of the active layer

A New Method to Solve Fractional Differential Equations: Inverse Fractional Shehu Transform Method

In this paper, we propose a new method called the inverse fractional Shehu transform method to solve homogenous and non-homogenous linear fractional differential equations. Fractional derivatives are described in the sense of Riemann-Liouville and Caputo. Illustrative examples are given to demonstrate the validity, efficiency and applicability of the presented method. The solutions obtained by the proposed method are in complete agreement with the solutions available in the literature

Metal salt modified PEDOT : PSS as anode buffer layer and its effect on power conversion efficiency of organic solar cells

The effects of metal chlorides such as LiCl, NaCl, CdCl2 and CuCl2 on optical transmittance, electrical conductivity as well as morphology of PEDOT:PSS films have been investigated. Transmittance spectra of spun PEDOT:PSS layers were improved by more than 6 to a maximum of 94 in LiCl doped PEDOT:PSS film. The surface of the PEDOT:PSS films has exhibited higher roughness associated with an increase in the electrical conductivity after doping with metal salts. The improvement in the physical properties of PEDOT:PSS as the hole transport layer proved to be key factors towards enhancing the P3HT:PCBM bulk heterojunction (BHJ) solar cells. These improvements include significantly improved power conversion efficiency with values as high as 6.82 associated with high fill factor (61) and larger short circuit current density (�18 mA cm-2). Keywords: Chlorine compounds; Conversion efficiency; Electric conductivity; Electrodes; Heterojunctions; Metals; Semiconductor doping; Solar cells, Electrode modification; Metal salt; Organic solar cell; P3HT:PCBM; PEDOT:PSS, Conducting polymer