Recent Techniques in Echocardiography: Two-Dimensional Echocardiography

Conventional M-mode echocardiography is a widely used noninvasive diagnostic technique. It allows bedside assessment of cardiac chamber dimensions, valve motion and left ventricular function. The limitations of this technique are that it (1) provides only a one-dimensional (icepick) view of the heart, (2) displays cardiac structures in an unfamiliar form that bears no resemblance to cardiac anatomy, and (3) does not provide information regarding spatial orientation of cardiac structures. These limitations led to the development of two-dimensional (2-D) real-time echocardiography in the last decade. The 2-D echo allows simultaneous visualization of cardiac structures in real time through multiple planes

Synthesis and Properties of a Series of 1,1,n,n-Tetramethyl[n](2,11)teropyrenophanes

The work described in this thesis revolves around the 1,1,n,ntetramethyl[n](2,11)teropyrenophanes, which are a series of [n]cyclophanes with a severely bent, board-shaped polynuclear aromatic hydrocarbons (PAH). The thesis is divided into seven Chapters. The first Chapter conatins an overview of the seminal work on [n]cyclophanes of the first two members of the “capped rylene” series of PAHs: benzene and pyrene. Three different general strategies for the synthesis of [n]cyclophanes are discussed and this leads in to a discussion of some slected syntheses of [n]paracyclopahnes and [n](2,7)pyrenophanes. The chemical, structural, spectroscopic and photophysical properties of these benzene and pyrene-derived cyclophanes are discussed with emphasis on the changes that occur with changes in the structure of the aromatic system. Chapter 1 concludes with a brief introduction to [n]cyclophanes of the fourth member of the capped rylene series of PAHs: teropyrene. The focus of the work described in Chapter 2 is the synthesis of of 1,1,n,ntetramethyl[n](2,11)teropyrenophane (n = 6 and 7) using a double-McMurry strategy. While the synthesis 1,1,7,7-tetramethyl[7](2,11)teropyrenophane was successful, the synthesis of the lower homologue 1,1,6,6-tetramethyl[6](2,11)teropyrenophane was not. The conformational behaviour of [n.2]pyrenophanes was also studied by 1H NMR spectroscopy and this provided a conformation-based rationale for the failure of the synthesis of 1,1,6,6-tetramethyl[6](2,11)teropyrenophane. Chapter 3 contains details of the synthesis of 1,1,n,n-tetramethyl[n](2,11)teropyrenophanes (n = 7-9) using a Wurtz / McMurry strategy, which proved to be more general than the double McMurry strategy. The three teropyrenophanes were obtained in ca. 10 milligram quantities. Trends in the spectroscopic properties that accompany changes in the structure of the teropyrene system are discussed. A violation of Kasha’s rule was observed when the teropyrenophanes were irradiated at 260 nm. The work described in the fourth Chapter concentrates on the development of gram-scale syntheses of 1,1,n,n-tetramethyl[n](2,11)teropyrenophanes (n = 7–10) using the Wurtz / McMurry strategy. Several major modifications to the orginal synthetic pathway had to be made to enable the first several steps to be performed comfortably on tens of grams of material. Solubility problems severely limited the amount of material that could be produced at a late stage of the synthetic pathways leading to the evennumbered members of the series (n = 8, 10). Ultimately, only 1,1,9,9- tetramethyl[9](2,11)teropyrenophane was synthesized on a multi-gram scale. In the final step in the synthesis, a valence isomerization / dehydrogenation (VID) reaction, the teropyrenophane was observed to become unstable under the conditions of its formation at n = 8. The synthesis of 1,1,10,10-tetramethyl[10](2,11)teropyrenophane was achieved for the first time, but only on a few hundred milligram scale. In Chapter 5, the results of an investigation of the electrophilic aromatic bromination of the 1,1,n,n-tetramethyl[n](2,11)teropyrenophanes (n = 7–10) are presented. Being the most abundant cyclophane, most of the work was performed on 1,1,9,9-tetramethyl[9](2,11)teropyrenophane. Reaction of this compound with varying amounts of of bromine revealed that bromination occurs most rapidly at the symmetryrelated 4, 9, 13 and 18 positions (teropyrene numbering) and that the 4,9,13,18- tetrabromide could be formed exclusively. Subsequent bromination occurs selectively on the symmetry-related 6, 7, 15 and 16 positions (teropyrene numbering), but considerably more slowly. Only mixtures of penta-, hexa-, hepta and octabromides could be formed. Bromination reactions of the higher and lower homologues (n = 7, 8 and 10) revealed that the reactivity of the teropyrene system increased with the degree of bend. Crystal structures of some tetra-, hexa-, hepta- and octa-brominated products were obtained. The goal of the work described in Chapter 6 is to use 1,1,9,9- tetramethyl[9](2,11)teropyrenophane as a starting material for the synthesis of warped nanographenophanes. A bromination, Suzuki-Miyaura, cyclodehydrogenation sequence was unsuccessful, as was a C–H arylation / cyclodehydrogenation approach. Itami’s recently-developed K-region-selective annulative -extension (APEX) reaction proved to be successful, affording a giant [n]cyclophane with a C84 PAH. Attempted bay-region Diels-Alder reactions and some cursory host-guest chemistry of teropyrenophanes are also discussed. In Chapter 7 a synthetic approach toward a planar model compound, 2,11-di-tbutylteropyrene, is described. The synthesis could not be completed owing to solubility problems at the end of the synthetic pathway

Experimental Investigations on The Effect of Tungsten Content on the Machining Behaviour of Tungsten Heavy Alloys

The present work attempts to assess the machinability of tungsten heavy alloys (WHAs) with varying tungsten content in terms of different machining characteristics such as chip thickness, material removal rate, cutting force and surface roughness under varied cutting conditions. The feed rate is found to have major influence on the machining characteristics; whereas the effect of rake angle appears to be marginal. With increase in W content both cutting force and material removal rate increase whereas surface roughness decreases. Since WHAs are difficult to machine, an additional objective of the study is to optimize machining parameters. An optimal balance of the experimental cutting parameters using Grey relational analysis has been achieved, which can be effectively employed for the machining of the alloys with close dimensional tolerances and desirable surface finish

Closed-loop digital meditation for neurocognitive and behavioral development in adolescents with childhood neglect.

Adverse childhood experiences are linked to poor attentive behaviors during adolescence, as well as increased risk for mental health disorders in adults. However, no study has yet tested targeted interventions to optimize neurocognitive processes in this population. Here, we investigated closed-loop digital interventions in a double-blind randomized controlled study in adolescents with childhood neglect, and evaluated the outcomes using multimodal assessments of neuroimaging, cognitive, behavioral, and academic evaluations. In the primary neuroimaging results, we demonstrate that a closed-loop digital meditation intervention can strengthen functional connectivity of the dorsal anterior cingulate cortex (dACC) in the cingulo-opercular network, which is critically developing during the adolescent period. Second, this intervention enhanced sustained attention and interference-resolution abilities, and also reduced behavioral hyperactivity at a 1-year follow-up. Superior academic performance was additionally observed in adolescents who underwent the digital meditation intervention. Finally, changes in dACC functional connectivity significantly correlated with improvements in sustained attention, hyperactivity, and academic performance. This first study demonstrates that closed-loop digital meditation practice can facilitate development of important aspects of neurocognition and real-life behaviors in adolescents with early childhood neglect

Hextuple-inverter configuration for multilevel nine-phase symmetrical open-winding converter

Abstract: Hextuple-inverter configuration for multilevel nine-phase symmetrical open-winding DC converter is articulated in this work. Power modular unit consists of six classical three-phase voltage source inverters (VSI). Each VSI includes one bi-directional device (MOSFET/IGBT) per each phase and link to two capacitors for neutral connection. A modified single carrier five-level modulation (MSCFM) algorithm is developed and modulates each 2-level VSI as 5- level multilevel inverter (MLI). A set of test results is presented, which are observed from the model based developments in numerical simulation software’s (Matlab/PLECS). The results always showed good conformity with the developed theoretical background under working conditions. The proposed converter found suited for (low-voltage/high current) electric vehicles, DC tractions and ‘More-Electric Aircraft’ applications

Fully coupled numerical model of actin treadmilling in the lamellipodium of the cell

This is the peer reviewed version of the following article: Kollepara, K. S., Mulye, P. D., Saez, P. Fully coupled numerical model of actin treadmilling in the lamellipodium of the cell. "International journal for numerical methods in biomedical engineering - Online", Desembre 2018, vol. 34, núm. 12, p. 1-21, which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/cnm.3143. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Cells rely on an interplay of subcellular elements for motility and migration. Certain regions of motile cells, such as the lamellipodium, are made of a complex mixture of actin monomers and filaments, which polymerize at the front of the cell, close to the cell membrane, and depolymerize at the rear. The dynamic actin turnover induces the so-called intracellular retrograde flow, and it is a fundamental process for cell motility. Apart from some comprehensive mathematical models, the computational modelling of actin treadmilling has been based on simpler biophysical models. Here, we adopt a highly detailed theoretical model of the actin treadmilling process and develop a coupled unsteady finite element formulation. We clearly describe the structure and implementation of the coupled problem within the finite element method. Our numerical results show an excellent correlation with experimental results from literature and with previous models. We include time dependent effects and convective transport terms, which expose puzzling dynamics in the retrograde flow. We propose several biological scenarios to analyze the behavior of the actin treadmilling along space and time. We observed response times of the main density variables in the order of seconds. Compared with previous analytical solutions, which make assumptions related to convective transport, transient dynamics, and actin fluxes, the generic solution can have significant influence on the retrograde flow. All together, our results unveil a promising applicability of classical finite element methods to derive an in silico testing platform for the actin treadmilling processes in motile cells, which could allow for an extension to other biophysical effects.Peer ReviewedPostprint (author's final draft

Characterising User Content on a Multi-lingual Social Network

Social media has been on the vanguard of political information diffusion in the 21st century. Most studies that look into disinformation, political influence and fake-news focus on mainstream social media platforms. This has inevitably made English an important factor in our current understanding of political activity on social media. As a result, there has only been a limited number of studies into a large portion of the world, including the largest, multilingual and multi-cultural democracy: India. In this paper we present our characterisation of a multilingual social network in India called ShareChat. We collect an exhaustive dataset across 72 weeks before and during the Indian general elections of 2019, across 14 languages. We investigate the cross lingual dynamics by clustering visually similar images together, and exploring how they move across language barriers. We find that Telugu, Malayalam, Tamil and Kannada languages tend to be dominant in soliciting political images (often referred to as memes), and posts from Hindi have the largest cross-lingual diffusion across ShareChat (as well as images containing text in English). In the case of images containing text that cross language barriers, we see that language translation is used to widen the accessibility. That said, we find cases where the same image is associated with very different text (and therefore meanings). This initial characterisation paves the way for more advanced pipelines to understand the dynamics of fake and political content in a multi-lingual and non-textual setting.Comment: Accepted at ICWSM 2020, please cite the ICWSM versio

Dobutamine-Atropine Stress Echocardiography for Reversible Dysfunction During the First Week After Acute Myocardial Infarction: Limitations and Determinants of Accuracy

AbstractObjectives. We sought to compare the accuracy of biphasic and ischemic responses and sustained improvement for reversible dysfunction and to identify causes of false negative and false positive findings.Background. Previous studies have shown that low dose dobutamine echocardiography was accurate for detecting reversible dysfunction after acute myocardial infarction (MI) but did not determine whether accuracy was improved by peak dose findings or influenced by the test interval or clinical or angiographic factors.Methods. Dobutamine-atropine stress echocardiography (DASE) (baseline, low dose [5 and 10 μg/kg body weight per min] and peak dose) and coronary angiography were performed in 115 patients 2 to 7 days after MI (test interval). Segmental wall thickening was analyzed according to the 16-segment model. Sustained improvement and biphasic and ischemic responses included improved wall thickening at low and peak doses, improved wall thickening at the low dose with worsening at peak dose and no change in wall thickening at the low dose with worsening at peak dose, respectively. Follow-up echocardiography was performed at 4 to 8 weeks, and reversible dysfunction was defined as improved wall thickening.Results. Wall thickening improved at follow-up in 305 (44%) of 688 dysfunctional segments. The test interval was 2 days in 16 patients, 3 days in 24, 4 days in 24, 5 days in 12, 6 days in 16 and 7 days in 23. No change at low and peak doses accurately predicted fixed dysfunction (318 [88%] of 360 segments), especially in akinetic and dyskinetic segments (276 [91%] of 303), irrespective of the test interval or clinical and angiographic factors. Ischemic segmental responses also predicted fixed dysfunction (63% [12 of 19 patients]), especially in medically treated compared with revascularized patients (100% [8 of 8] vs. 36% [4 of 11], p = 0.013). Both biphasic responses and sustained improvement (77% [179 of 231 segments] vs. 87% [84 of 97], p = 0.082) were highly predictive of reversible dysfunction, especially in akinetic segments, irrespective of the test interval or clinical and angiographic factors. The only limitation was reduced accuracy (77% [177 of 222 segments], p < 0.001) due to false positive results (16%) in hypokinetic segments.Conclusions. No change and ischemic responses during DASE were specific for fixed dysfunction. Improved wall thickening at the low dose, irrespective of changes at peak dose, was highly predictive of reversible dysfunction. Accuracy was only limited by false positive results in hypokinetic segments and not by the test interval or clinical or angiographic factors

An original transformer and switched-capacitor (T &amp; SC)-based extension for DC-DC boost converter for high-voltage/low-current renewable energy applications:Hardware implementation of a new T &amp; SC boost converter

In this article a new Transformer and Switched Capacitor-based Boost Converter (T &amp; SC-BC) is proposed for high-voltage/low-current renewable energy applications. The proposed T &amp; SC-BC is an original extension for DC-DC boost converter which is designed by utilizing a transformer and switched capacitor (T &amp; SC). Photovoltaic (PV) energy is a fast emergent segment among the renewable energy systems. The proposed T &amp; SC-BC combines the features of the conventional boost converter and T &amp; SC to achieve a high voltage conversion ratio. A Maximum Power Point Tracking (MPPT) controller is compulsory and necessary in a PV system to extract maximum power. Thus, a photovoltaic MPPT control mechanism also articulated for the proposed T &amp; SC-BC. The voltage conversion ratio (Vo/Vin) of proposed converter is (1 + k)/(1 − D) where, k is the turns ratio of the transformer and D is the duty cycle (thus, the converter provides 9.26, 13.88, 50/3 voltage conversion ratios at 78.4 duty cycle with k = 1, 2, 2.6, respectively). The conspicuous features of proposed T &amp; SC-BC are: (i) a high voltage conversion ratio (Vo/Vin); (ii) continuous input current (Iin); (iii) single switch topology; (iv) single input source; (v) low drain to source voltage (VDS) rating of control switch; (vi) a single inductor and a single untapped transformer are used. Moreover, the proposed T &amp; SC-BC topology was compared with recently addressed DC-DC converters in terms of number of components, cost, voltage conversion ratio, ripples, efficiency and power range. Simulation and experimental results are provided which validate the functionality, design and concept of the proposed approach

Effects of potassium levels on growth and productivity of potato varieties in inner terai of Nepal

Potassium is an essential nutrient for potato due to its direct effects on the growth, yield and quality of potato tubers. This study was carried out at Lamahi, Dang Nepal during winter season of 2018. Two potato variety (Local and Cardinal) and five levels of potassium (30, 40, 60, 80 and 100 kg K2O/ha) were evaluated in two factorial randomized block design with three replications. The application of potassium at 100 kg/ha produced significantly highest plant canopy, stem diameter and leaf length for the both varieties. The highest tuber number per plant (10.3 for Local and 17.6 for cardinal) and tuber weight (19.7 g for Local and 49 g for Cardinal) were obtained with the application of 100 kg K2O/ha. The highest gross margin was found with this level of potassium. Therefore, farmers should apply 100 kg K2O to potato to achieve maximum production and benefit.&nbsp