bluuebunny/crossref_metadata_2025_split huggingface dataset:
Model order reduction for left ventricular mechanics via congruency training
Authors: Di Achille Paolo , Parikh Jaimit , Khamzin Svyatoslav , Solovyova Olga , Kozloski James , Gurev Viatcheslav 
Published: July 2019

AbstractComputational models of the cardiovascular system and heart function are currently being investigated as analytic tools to assist medical practice and clinical trials. Recent technological advances allow for finite element models of heart ventricles and atria to be customized to medical images and to assimilate electrical and hemodynamic measurements. Optimizing model parameters to physiological data is, however, challenging due to the computational complexity of finite element models. Metaheuristic algorithms and other optimization strategies typically require sampling hundreds of points in the model parameter space before converging to optimal solutions. Similarly, resolving uncertainty of model outputs to input assumptions is difficult for finite element models due to their computational cost. In this paper, we present a novel, multifidelity strategy for model order reduction of 3-D finite element models of ventricular mechanics. Our approach is centered around well established findings on the similarity between contraction of an isolated muscle and the whole ventricle. Specifically, we demonstrate that simple linear transformations between sarcomere strain (tension) and ventricular volume (pressure) are sufficient to reproduce global pressure-volume outputs of 3-D finite element models even by a reduced model with just a single myocyte unit. We further develop a procedure for congruency training of a surrogate low-order model from multi-scale finite elements, and we construct an example of parameter optimization based on medical images. We discuss how the presented approach might be employed to process large datasets of medical images as well as databases of echocardiographic reports, paving the way towards application of heart mechanics models in the clinical practice.
Tail Vein Injections of Recombinant Human Thioredoxin Prevents High Fat-induced Endothelial Dysfunction in Mice
Authors: Hilgers Rob H.P. 
Published: July 2019

AbstractBackgroundObesity is a serious risk factor for cardiovascular diseases. A high fat diet results in cellular oxidative stress and endothelial dysfunction in resistance-sized arteries, characterized by reduced nitric oxide (NO) and endothelium-dependent hyperpolarizing (EDH) responses. Thioredoxin-1, a sulfo-oxidoreductase protein that cleaves disulfide bridges between two adjacent cysteine residues in oxidized proteins, has been shown to lower blood pressure and improve endothelium-dependent relaxing responses in aged C57Bl6/J mice.Methods and ResultsYoung (∼ 3 month-old) male C57Bl6/J mice were fed a high fat diet (42% kcal from fat; obese) or a normal chow (lean) for 3 months. Mice were administered recombinant human thioredoxin-1 (rhTrx; 25 mg/kg) or saline (0.9% NaCl) via tail vein injection at the start, after one month, and after two months. Body weight (BW) was comparable between lean/rhTrx1 and lean/saline at the time of euthanasia (32 ±1 g versus 32 ± 1 g). The high fat regimen resulted in a comparable BW between obese/saline and obese/rhTrx mice (47 ± 1 g versus 45 ± 2 g, respectively). Small (second-order branches) mesenteric arteries (MA2), coronary and femoral arteries were isolated and mounted on the wire-myograph. MA2 and femoral arteries from obese/saline had blunted acetylcholine (10−9 – 10−5 M)-mediated relaxations compared to lean/saline mice, but not to the NO donor sodium nitroprusside. NO and EDH-mediated relaxing responses were blunted in MA2 from obese/lean mice compared to the three other groups.ConclusionTail vein injections with rhTrx prevented endothelial dysfunction in obese mice by improving NO and EDH relaxing responses in MA2.
Numerical study of boundary layer transition using intermittency model
Authors: Tatar Massoud , Tahani Mojtaba , Masdari Mehran 
Published: July 2019

Purpose
In this paper, the applicability of shear stress transport k-ω model along with the intermittency concept has been investigated over pitching airfoils to capture the laminar separation bubble (LSB) position and the boundary layer transition movement. The effect of reduced frequency of oscillations on boundary layer response is also examined.

Design/methodology/approach
A two-dimensional computational fluid dynamic code was developed to compute the effects of unsteadiness on LSB formation, transition point movement, pressure distribution and lift force over an oscillating airfoil using transport equation of intermittency accompanied by the k-ω model.

Findings
The results indicate that increasing the angle of attack over the stationary airfoil causes the LSB size to shorten, leading to a rise in wall shear stress and pressure suction peak. In unsteady cases, both three- and four-equation models are capable of capturing the experimentally measured transition point well. The transition is delayed for an unsteady boundary layer in comparison with that for a static airfoil at the same angle of attack. Increasing the unsteadiness of flow, i.e. reduced frequency, moves the transition point toward the trailing edge of the airfoil. This increment also results in lower static pressure suction peak and hence lower lift produced by the airfoil. It was also found that the fully turbulent k-ω shear–stress transport (SST) model cannot capture the so-called figure-of-eight region in lift coefficient and the employment of intermittency transport equation is essential.

Practical implications
Boundary layer transition and unsteady flow characteristics owing to airfoil motion are both important for many engineering applications including micro air vehicles as well as helicopter blade, wind turbine and aircraft maneuvers. In this paper, the accuracy of transition modeling based on intermittency transport concept and the response of boundary layer to unsteadiness are investigated.

Originality/value
As a conclusion, the contribution of this paper is to assess the ability of intermittency transport models to predict LSB and transition point movements, static pressure distribution and aerodynamic lift variations and boundary layer flow pattern over dynamic pitching airfoils with regard to oscillation frequency effects for engineering problems.
Information-based quality management in reverse logistics supply chain
Authors: Jayasinghe Ruchini Senarath , Chileshe Nicholas , Rameezdeen Raufdeen 
Published: July 2019

Purpose
The purpose of this paper is to explore the synergies among reverse logistics supply chain (RLSC), quality management (QM) and information management (IM) concepts to enhance the effectiveness of demolition waste management (DWM) practices.

Design/methodology/approach
A systematic literature review was conducted using 70 articles published between the years of 2006 and 2017, which were subjected to descriptive and thematic analysis.

Findings
The descriptive analysis established that the RLSC concept was dealt within the majority of the publications (61 per cent), followed by concepts related to quality in RLSC (24 per cent). Only 14 per cent of the articles were based on IM concepts related to RLSC. Quality and information are interrelated in the effective implementation of RLSC. The thematic analysis demonstrated that there is a need for using quality parameters in a regulatory environment in an information-based environment. Based on the findings, future research directions were developed.

Research limitations/implications
The study encourages researchers to identify novel directions by combining these three concepts. The study developed a future research agenda regarding use of building information modelling (BIM) for existing buildings under novel technologies; analysis of secondary market demand and supply; and assessment of cost and safety management with quality in a BIM-enabled environment.

Practical implications
The practical implications include the application of sustainable management principles based on stakeholders and the regulatory environment.

Originality/value
Integration of the three concepts is an emerging area. This integration developed a robust approach to achieve QM in RLSC operations under a sound information flow enabling the optimisation of DWM.
Evaluation of the usability of the Canay’s equivalent circuit diagrams for the calculation of subsynchronous resonances
Authors: Gołębiowski Marek , Göbel Carsten 
Published: July 2019

Purpose
In the shaft and end windings of large turbogenerators, unacceptably high mechanical stresses can occur as a result of subsynchronous resonances (SSRs) in the system network-generator-shaft. These stresses can cause severe damages. Subsynchronous resonances are characterized by the occurrence of currents and electromagnetic torques in the air gap of the generator with frequencies that are significantly below the synchronous frequency. When simulating the balancing processes in multi-machine networks, the generators are represented by Canay’s equivalent circuit diagrams. The parameters used here are determined from geometric dimensions of the generator, taking into account material properties, and verified by means of surge short-circuit tests in which the 50 and 100 Hz components are dominant. This paper aims to examine whether the parameters of the equivalent circuit diagram determined in this way reproduce correctly the dynamic behavior of a synchronous machine, even if the SSR occur.

Design/methodology/approach
The simulation program NETOMAC is used to simulate the SSRs for different parameters. The results of these simulations are then compared with those obtained by the finite difference (FD) method calculations.

Findings
The comparison of the waveforms calculated with NETOMAC and FELMEC for an SSR shows that the original equivalent circuit diagram parameters provide satisfactory results. An extension of Canay’s equivalent circuit diagram is not necessary. Optimization of the discussed parameters leads to a significant improvement in comparison to the calculation with the parameters from the generator data sheet.

Originality/value
The unresolved doubt has been proven, that the Parka generator model with the manufacturer’s parameters can also be used for subsynchronous studies of electromechanical resonances of systems. However, it was advisable to improve the simulation results by optimizing the generator parameters used in the calculations. By optimizing the parameters for the SSRs, the calculation of the occurring torques has been significantly improved.
Modelling and co-simulation of a permanent magnet synchronous generator
Authors: Quintal-Palomo Roberto Eduardo , Gwozdziewicz Maciej , Dybkowski Mateusz 
Published: July 2019

Purpose
The purpose of this paper is to obtain an accurate methodology for modelling and analysis of the permanent magnet synchronous generator connected to power electronic components.

Design/methodology/approach
This paper presents the methodology of the co-simulation of a permanent magnet synchronous generator. It combines Simulink, Maxwell and Simplorer software to demonstrate the electrical machine behaviour connected with the power electronics’ circuit. The finite element analysis performed on the designed machine exhibit a more accurate behaviour over simplified Simulink models. Results between both simulation and co-simulation are compared to measurements.

Findings
The co-simulation approach offers a more accurate depiction of the machine behaviour and its interaction with the non-linear circuits.

Research limitations/implications
This paper focuses on the interior permanent magnet type of PMSG and its interaction with a passive rectifier (nonlinear circuit).

Practical implications
The advanced capabilities of the co-simulation method allow to analyse more variations (geometry, materials, etc.), and its interaction with non-linear circuits, than previous simulation techniques.

Originality/value
The co-simulation as a tool for analysis and design of systems interconnected with unconventional and conventional electrical machines and prototypes, and the comparison of the obtained results with classical analysis and design methods, against measurements obtained from the prototype.
Simultaneous effects of multiple cues in restaurant reviews
Authors: Kim Esther L. , Tanford Sarah 
Published: July 2019

PurposeThe purpose of this paper is to evaluate how consumers simultaneously process multiple cues for different dining occasions when making a restaurant decision.Design/methodology/approachThis paper investigates the influence of priming (review prototype), effort (distance) and involvement (occasion) on restaurant evaluations, willingness to drive and willingness to pay for a restaurant meal. A 2 (prototype: negative, positive) × 2 (distance: close, far) × 2 (occasion: casual, special) between-subjects factorial design was used.FindingsThe paper finds that each variable influences a different outcome, whereby people rely on a review prototype for restaurant evaluation and choice, a distance cue for willingness to drive and a dining occasion for willingness to pay.Practical implicationsThis paper suggests that restaurant marketers can highlight exemplary service through online reviews, increase profitability by promoting special occasions and geographically expand their market by attracting people to drive for a special dinner.Originality/valueThis paper evaluates the simultaneous interactive effects of multiple cues in service settings. It demonstrates that situational cues moderate the effect of primary cues in online reviews.
Frost maintains forests and grasslands as alternate states in a montane tropical forest–grassland mosaic; but alien tree invasion and warming can disrupt this balance
Authors: Joshi Atul A. , Ratnam Jayashree , Sankaran Mahesh 
Published: July 2019

Abstract

Forest–grassland mosaics, with abrupt boundaries between the two vegetation types, occur across the globe. Fire and herbivory are widely considered primary drivers that maintain these mosaics by limiting tree establishment in grasslands, while edaphic factors and frosts are generally considered to be secondary factors that reinforce these effects. However, the relative importance of these drivers likely varies across systems. In particular, although frost is known to occur in many montane tropical mosaics, experimental evidence for its role as a driving factor is limited.

We used replicated in situ transplant and warming experiments to examine the role of microclimate (frost and freezing temperatures) and soil in influencing germination and seedling survival of both native forest trees and alien invasive Acacia trees in grasslands of a tropical montane forest–grassland mosaic in the Western Ghats of southern India.

Seed germination of both native and alien tree species was higher in grasslands regardless of soil type, indicating that germination was not the limiting stage to tree establishment. However, irrespective of soil type, native seedlings in grasslands incurred high mortality following winter frosts and freezing temperatures relative to native seedlings in adjoining forests where freezing temperatures did not occur. Seedling survival through the tropical winter was thus a primary limitation to native tree establishment in grasslands. In contrast, alien Acacia seedlings in grasslands incurred much lower levels of winter mortality. Experimental night‐time warming in grasslands significantly enhanced over‐winter survival of all tree seedlings, but increases were much greater for alien Acacia than for native tree seedlings.

Synthesis. Our results provide evidence for a primary role for frost and freezing temperatures in limiting tree establishment in grasslands of this tropical montane forest–grassland mosaic. Future increases in temperature are likely to release trees from this limitation and favour tree expansion into grasslands, with rates of expansion of non‐native Acacia likely to be much greater than that of native trees. We suggest that studies of frost limitation to plant establishment are needed across a range of tropical ecosystems to re‐evaluate the general importance of frost as a driver of vegetation transitions in the tropics.
The role of glycine betaine in range expansions; protecting mangroves against extreme freeze events
Authors: Hayes Matthew A. , Shor Audrey C. , Jesse Amber , Miller Christopher , Kennedy John P. , Feller Ilka 
Published: July 2019

Abstract

Due to a warming climate, mangrove populations within the Gulf of Mexico and along the Florida Atlantic coastline are expanding their range poleward. As mangroves expand their range limit, leading edge individuals are more likely to experience an increased incidence of freeze events. However, we still lack a clear understanding of the mechanisms used by mangroves to survive freezing conditions.

Here, we conducted common garden experiments at different locations experiencing variable winter freeze conditions to show glycine betaine, an organic osmolyte, increases significantly with freeze exposure, playing an important role in the freeze tolerance of Avicennia germinans, a widespread Neotropical mangrove.

We found glycine betaine accumulation was similar across all source populations and freeze exposure locations, suggesting glycine betaine is not a range limit adaptation and is instead used for freeze tolerance by A. germinans irrespective of source population. Plants sourced from populations that experience freezing conditions exhibited greater rates of survival, indicating range edge populations of A. germinans have other heritable adaptations in addition to glycine betaine for freeze tolerance.

Synthesis. Continued mangrove expansion poleward will result in a greater incidence of freeze events for individuals at the leading edge. Our findings suggest freeze tolerance in this species may be genetically based and that leading edge A. germinans have the potential to survive extreme freeze events and recover post‐freeze, allowing for their continued expansion poleward. This process of selective survival may act to promote adaptation of freeze tolerance in range edge populations.
Calycosin induces apoptosis in adenocarcinoma HT29 cells by inducing cytotoxic autophagy mediated by SIRT1/AMPK‐induced inhibition of Akt/mTOR
Authors: El‐kott Attalla Farag , Al‐kahtani Mohammed Ali , Shati Ali A. 
Published: July 2019

AbstractAutophagy promotes cell survival or induces apoptosis in cancer cells. While SIRT1 and AMPK induce autophagy in both normal and cancer cells, Akt and mTOR can inhibit it. Calycosin, a methoxyisoflavone, protects against several types of solid tumours including colorectal cancer. However, the mechanisms behind the antitumour effect of Calycosin remain largely unknown. This study investigates if autophagy mediates the anti‐tumourigenesis effect afforded by Calycosin and examines if this effect involves activation of SIRT1 and/or AMPK. Human colorectal (HT29) carcinoma cells were cultured under normal conditions with Calycosin (50 μmol/L) in the presence or absence of chloroquine (10 μmol/L), EX‐527 (100 nmol/L, SIRT1 inhibitor), or IGF‐1 (100 ng/mL, Akt/mTOR activator) for 48 hours. Calycosin inhibited cell growth, proliferation and invasion and increased protein levels of Beclin‐1 and LC3II, markers of autophagy. It significantly increased protein levels of cleaved caspase‐3, Bax, and SIRT1, and activity of AMPK and reduced those of Bcl‐2. These effects were parallel with concomitant reduction in protein levels p‐src, integrin‐β1 and Cyclin‐D1 and activities of Akt and mTOR. Inhibition of autophagy by CQ reversed all these effects except cell invasion. Interestingly, co‐incubating the cells with either EX‐527 or IGF‐1 completely prevented Calycosin‐induced autophagy and all other associated effects and increased cell invasion. Also, blockade of SIRT‐1 prevented the activation of AMPK, Akt, and mTOR, suggesting it to be an upstream regulator of these markers. In conclusion, Calycosin stimulates CRC cell apoptosis and inhibits their invasion by acting as SIRT1 activator which induces activation of AMPK‐induced inhibition of Akt/mTOR axis.
How do stroke survivors with communication difficulties manage life after stroke in the first year? A qualitative study
Authors: Wray Faye , Clarke David , Forster Anne 
Published: July 2019

AbstractBackgroundInterest in how stroke survivors might be better supported to manage life after stroke has grown rapidly in recent years, with a particular emphasis on enabling ‘self‐management’. Post‐stroke communication difficulties may pose a unique barrier to longer term adaptation and adjustment. It is important to understand how stroke survivors with communication difficulties manage life after stroke and what support may be needed to facilitate this process.AimsTo explore how stroke survivors with communication difficulties manage life after stroke in the first year.Methods & ProceduresA cross‐sectional qualitative study involving in‐depth semi‐structured interviews with stroke survivors with communication difficulties (aphasia, dysarthria or apraxia of speech) and/or their family members at single time points during the first year post‐stroke. A total of 21 participants (14 stroke survivors and seven family members) took part in interviews for the study. Interview data were analysed using thematic analysis.Outcome & ResultsA total of six themes were identified: (1) strategies to manage changes to communication; (2) testing communication outside of the home; (3) balancing support and independence; (4) hope for recovery; (5) obtaining support from healthcare professionals; and (6) adapting activities and keeping busy. Stroke survivors with communication difficulties and their family members undertook significant work (practical, relational, emotional) to manage their condition. Adaptation and adjustment was often facilitated by ‘doing’; testing out which activities could be managed independently and which required additional support. Some stroke survivors and their family members demonstrated considerable resourcefulness and creativity in developing strategies to manage their communication difficulties. Despite the work undertaken, many expressed a lack of confidence in their ability and feelings of powerlessness and abandonment at the point of discharge from community services.Conclusions & ImplicationsStroke survivors and their family members develop personally meaningful and context‐specific strategies to adjust to and manage life after stroke. Future interventions should recognize, support and build upon the active work already undertaken by stroke survivors with communication difficulties and their families. Further support before and around the point of discharge from community services may be needed to help build confidence and skills to manage in the longer term. The benefit of a supported self‐management approach for stroke survivors with communication difficulties should be further investigated.