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Numerical Methods for Fluid-Structure Interaction—A Review

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Communications in Computational Physics 2012年第7期12卷 337-377页

作者： Gene Hou Jin Wang anita layton Department of Mechanical and Aerospace Engineering Old Dominion UniversityNorfolkVA 23529USA Department of Mathematics and Statistics Old Dominion UniversityNorfolkVA 23529USA Department of Mathematics Duke UniversityDurhamNC 27708USA

The interactions between incompressible fluid flows and immersed structures are nonlinearmulti-physics phenomena that have applications to a wide range of scientific and engineering *** this article,we review representative numericalmethods based on conforming and non-conformingmeshes that are currently available for computing fluid-structure interaction problems,with an emphasis on some of the recent developments in the field.A goal is to categorize the selected methods and assess their accuracy and *** discuss challenges faced by researchers in this field,and we emphasize the importance of interdisciplinary effort for advancing the study in fluid-structure interactions.

关键词： Fluid-structure interaction conforming and non-conforming meshes immersed methods

Computing Viscous Flow in an Elastic Tube

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Numerical Mathematics(Theory,Methods and Applications) 2014年第4期7卷 555-574页

作者： Yi Li Ioannis Sgouralis anita T.layton Department of Mathematics Duke UniversityDurhamNCUSA

We have developed a numerical method for simulating viscous flow through a compliant closed tube,driven by a pair of fluid source and *** is natural for tubular flow simulations,the problem is formulated in axisymmetric cylindrical coordinates,with fluid flow described by the Navier-Stokes *** the tubular walls are assumed to be elastic,when stretched or compressed they exert forces on the *** these forces are singularly supported along the boundaries,the fluid velocity and pressure fields become *** accurately compute the solution,we use the velocity decomposition approach,according to which pressure and velocity are decomposed into a singular part and a remainder *** singular part satisfies the Stokes equations with singular boundary *** the Stokes solution is unsmooth,it is computed to second-order accuracy using the immersed interface method,which incorporates known jump discontinuities in the solution and derivatives into the finite difference *** remainder part,which satisfies the Navier-Stokes equations with a continuous body force,is *** equations describing the remainder part are discretized in time using the semi-Lagrangian approach,and then solved using a pressure-free projection *** results indicate that the computed overall solution is secondorder accurate in space,and the velocity is second-order accurate in time.

关键词： Navier-Stokes flow axisymmetry immersed boundary fluid-structure interaction

A Hybrid Immersed Interface Method for Driven Stokes Flow in an Elastic Tube

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Numerical Mathematics(Theory,Methods and Applications) 2013年第4期6卷 600-616页

作者： Yi Li Sarah A.Williams anita T.layton Department of Mathematics Duke UniversityDurhamNC 27708-0320USA

We present a hybrid numerical method for simulating fluid flow through a compliant,closed tube,driven by an internal source and *** is assumed to be highly viscous with its motion described by Stokes *** geometry is assumed to be axisymmetric,and the governing equations are implemented in axisymmetric cylindrical coordinates,which capture 3D flow dynamics with only 2D *** solve the model equations using a hybrid approach:we decompose the pressure and velocity fields into parts due to the surface forcings and due to the source and sink,with each part handled separately by means of an appropriate *** the singularly-supported surface forcings yield an unsmooth solution,that part of the solution is computed using the immersed interface *** conditions are derived for the axisymmetric cylindrical *** velocity due to the source and sink is calculated along the tubular surface using boundary *** results are presented that indicate second-order accuracy of the method.

关键词： Stokes flow interface tracking immersed interface methods axisymmetric cylindrical coordinates boundary integrals

Theoretical assessment of the Ca^2＋ oscillations in the afferent arteriole smooth muscle cell of the rat kidney

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International Journal of Biomathematics 2018年第3期11卷 267-287页

作者： Ning Wei anita T. layton Department of Mathematics Duke University Durham NC USA

The afferent arteriole （AA） of rat kidney exhibits the myogenic response, in which the vessel constricts in response to an elevation in blood pressure and dilates in response to a pressure reduction. Additionally, the AA exhibits spontaneous oscillations in vascular tone at physiological luminal pressures. These time-periodic oscillations stem from the dynamic exchange of Ca^2＋ between the cytosol and the sarcoplasmie reticulum, cou- pled to the stimulation of Ca^2＋-activated potassium and chloride channels, and to the modulation of voltage-gated L-type Ca^2＋ channels. The effects of physiological factors, including blood pressure and vasoactive substances, on AA vasomotion remain to be well characterized. In this paper, we analyze a mathematical model of Ca^2＋ signaling in an AA smooth muscle cell. The model represents detailed transmembrane ionic trans- port, intracellular Ca^2＋ dynamics as well as kinetics of nitric oxide （NO） and superoxide （O2^-） formation, diffusion and reaction. NO is an important factor in the maintenance of blood pressure and O2^- has been shown to contribute significantly to the functional alternations of blood vessels in hypertension. We perform a bifurcation analysis of the model equations to assess the effect of luminal pressure, NO and O2^- on the behaviors of limit cycle oscillations.

关键词： Afferent arteriole limit cycle oscillation bifurcation analysis nitric oxide superoxide.

Use of MLC901 in cerebral venous sinus thrombosis:Three case reports

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World Journal of Clinical Cases 2024年第2期12卷 346-353页

作者： anita Ante Arsovska Narayanaswamy Venketasubramanian Department of Urgent Neurology University Clinic of NeurologyUniversity Ss.Cyril and Methodius-Faculty of MedicineSkopje 1000North Macedonia Department of Neurology Raffles HospitalSingapore 188770Singapore

BACKGROUND Cerebral venous sinus thrombosis(CVT)is rare cause of cerebrovascular *** incidence is 0.5%of all *** majority of affected patients are young adults(mean age:35-40 years)with mild to moderate *** outcome with severe disability is seen in 13%of *** diagnosis and treatment are important for good outcomes and preventing *** options are limited and mostly based on *** II™(MLC901;Moleac Pte,Ltd,Singapore)has a potential beneficial role in post-stroke recovery,by aiding the natural brain recovery *** SUMMARY MLC901 consists of nine natural herbal *** have shown its safety profile and aid in post stroke *** aim of this case series was to demonstrate the potential role of MLC901 in stroke recovery of patients with cerebral venous sinus thrombosis(CVST)who received MLC901 in addition to standard of *** prescribed dose of MLC901 is 400 mg/cap two capsules,three times a *** from these patients were prospectively collected at baseline and at monthly visits,for a duration of 3 *** measures included adherence to therapy,side effects,National Institutes of Health Stroke Scale,Glasgow Coma Scale,modified Rankin Scale,and the Short Orientation-Memory-Concentration ***901 was well tolerated and no side effects were *** patients were stable with improved *** This case series highlights the potential therapeutic effects of MLC901 on CVST and provides support for further studies.

关键词： MLC901 Cerebral venous sinus thrombosis Anticoagulation therapy Safety Case report

Portal hypertension in patients with nonalcoholic fatty liver disease:Current knowledge and challenges

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World Journal of Gastroenterology 2024年第4期30卷 290-307页

作者： anita Madir Ivica Grgurevic Emmanuel A Tsochatzis Massimo Pinzani Department of Gastroenterology Hepatology and Clinical NutritionUniversity Hospital DubravaZagreb 10000Croatia School of Medicine University of ZagrebZagreb 10000Croatia Faculty of Pharmacy and Biochemistry University of ZagrebZagreb 10000Croatia UCL Institute for Liver and Digestive Health Royal Free Hospital and University College LondonLondon NW32PFUnited Kingdom

Portal hypertension(PH)has traditionally been observed as a consequence of significant fibrosis and cirrhosis in advanced non-alcoholic fatty liver disease(NAFLD).However,recent studies have provided evidence that PH may develop in earlier stages of NAFLD,suggesting that there are additional pathogenetic mechanisms at work in addition to liver *** early development of PH in NAFLD is associated with hepatocellular lipid accumulation and ballooning,leading to the compression of liver *** compression and intraluminal obstacles cause mechanical forces such as strain,shear stress and elevated hydrostatic pressure that in turn activate mechanotransduction pathways,resulting in endothelial dysfunction and the development of *** spatial distribution of histological and functional changes in the periportal and perisinusoidal areas of the liver lobule are considered responsible for the pre-sinusoidal component of PH in patients with ***,current diagnostic methods such as hepatic venous pressure gradient(HVPG)measurement tend to underestimate portal pressure(PP)in NAFLD patients,who might decompensate below the HVPG threshold of 10 mmHg,which is traditionally considered the most relevant indicator of clinically significant portal hypertension(CSPH).This creates further challenges in finding a reliable diagnostic method to stratify the prognostic risk in this population of *** theory,the measurement of the portal pressure gradient guided by endoscopic ultrasound might overcome the limitations of HVPG measurement by avoiding the influence of the pre-sinusoidal component,but more investigations are needed to test its clinical utility for this *** and spleen stiffness measurement in combination with platelet count is currently the best-validated non-invasive approach for diagnosing CSPH and varices needing *** change remains the cornerstone of the treatment of PH in NAFLD,together with correcting the comp

关键词： Non-alcoholic fatty liver disease Portal hypertension Mechanotransduction Endothelial dysfunction Hepatic venous pressure gradient

A passive,reusable,and resonating wearable sensing system for ondemand,non-invasive,and wireless molecular stress biomarker detection

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Nano Research 2024年第8期17卷 7542-7556页

作者： Shingirirai Chakoma Xiaochang Pei Huiting Qin anita Ghandehari Sahar NajafiKhoshnoo Jerome Rajendran Rahim Esfandyarpour Department of Electrical Engineering and Computer Science University of CaliforniaIrvineCA 92697USA Laboratory for Integrated Nano BioElectronics Innovation The Henry Samueli School of EngineeringUniversity of CaliforniaIrvineCA 92697USA Henry Samueli School of Engineering University of CaliforniaIrvineCA 92697USA

The significant impact of stress on health necessitates accurate assessment methods,where traditional questionnaires lack reliability and *** advancements like wearables with electrocardiogram(ECG)and galvanic skin response(GSR)sensors face accuracy and artifact *** biosensors detecting cortisol,a critical stress hormone,present a promising ***,existing cortisol assays,requiring saliva,urine,or blood,are complex,expensive,and unsuitable for continuous *** study introduces a passive,molecularly imprinted polymer-radio-frequency(MIP-RF)wearable sensing system for real-time,non-invasive sweat cortisol *** system is wireless,flexible,battery-free,reusable,environmentally stable,and designed for long-term monitoring,using an inductance-capacitance *** transducer translates cortisol concentrations into resonant frequency shifts with high sensitivity(~160 kHz/(log(μM)))across a physiological range of 0.025–1μ*** with near-field communication(NFC)for wireless and battery-free operation,and threedimensional(3D)-printed microfluidic channel for in-situ sweat collection,it enables daily activity cortisol level *** of cortisol circadian rhythm through morning and evening measurements demonstrates its effectiveness in tracking and monitoring sweat cortisol levels.A 28-day stability test and the use of cost-effective 3D nanomaterials printing enhance its economic viability and *** innovation paves the way for a new era in realistic,on-demand health monitoring outside the laboratory,leveraging wearable technology for molecular stress biomarker detection.

关键词： cortisol wearable flexible sensors three-dimensional(3D)nanomaterials printing reusable environmentally stable

A multi-sensor appiproach to calving detection

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Information Processing in Agriculture 2024年第1期11卷 45-64页

作者： anita Z.Chang David L.Swain Mark G.Trotter Institute for Future Farming Systems School of HealthMedicaland Applied SciencesCentral Queensland UniversityRockhamptonQueensland 4700Australia

The advent of remote livestock monitoring systems provides numerous possibilities for improving on-farm productivity,efficiency,and *** potential application for these systems is for the detection of calving *** study describes the integration of data from multiple sensor sources,including accelerometers,global navigation satellite systems(GNsS),an accelerometer-derived rumination algorithm,a walk-over-weigh unit,and a weather station for parturition detection using a support vector machine *** best performing model utilised data from GNsS,the ruminating algorithm,and weather stations to achieve 98.6%accuracy,with 88.5%sensitivity and 100%*** topranking features of this model were primarily GNSS *** study provides an overview as to how various sensor systems could be integrated on-farm to maximise calving detection for improved production and welfare outcomes.

关键词： Accelerometer GNSS GPS Rumination Sensor WOW

Influence of edaphic factors on distribution and condition of Himalayan silver birch(Betula utilis ***)communities in the northwestern Indian Himalayas

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Journal of Mountain Science 2024年第2期21卷 590-606页

作者： Khashti DASILA Renu RAWAL Tanay BARMAN Sher Singh SAMANT anita PANDEY Veena PANDE G.B.Pant National Institute of Himalayan Environment Almora 263643India Centre of Excellence on Sustainable Land Management Indian Council of Forestry Research and EducationDehradun 248006India Uttarakhand State Council for Science&Technology Dehradun 248015India Department of Biotechnology Graphic Era(Deemed to be University)Dehradun 248002India Department of Biotechnology Kumaun UniversityNainital 263136India

The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services,functions,disturbance,and resilience that lead to the development of integrated areas such as ecological niche modeling and contribute to identifying the valuable bio-indicators which can be used in framing conservation and management *** is one of the most dominant tree species of treeline ecotone in the Himalayan *** species is also considered as indicator species for monitoring the past and recent climate change *** current study was carried out in the natural populations of *** from the sub-alpine zone of North-western Indian *** birch dominated forest harbors a total of 305 plant species comprising Angiosperms(51 families,160 genera and 277 species),Gymnosperms(03 families,05 genera and 07 species)and Pteridophytes(07 families,11 genera and 21 species)with Asteraceae,Ranunculaceae and Rosaceae as dominant *** forests are found dominant in shady moist habitat and North West *** characteristics,anthropogenic and developmental activities affect the population structure of *** and associated ***,the species has fair regeneration status in the study *** acidic nature of soil pH and spatial variation in edaphic characteristics may be due to geographical differences,rooting patterns and litter accumulation of below and above-ground *** estimation of a representative population of *** from each site showed that TAGBD,TCD and TBD were found maximum in ST3(Hamta Pass II site).The CCA analysis determined that environmental variables such as altitude,organic matter,available phosphorous,organic carbon,available nitrogen,and electrical conductivity played a significant role in determining tree species composition and distribution in *** dominated forests.

关键词： Species composition Indicator species Biomass North-western Indian Himalaya Regeneration Environmental variables