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An Efficient,Energy Stable Scheme for the Cahn-Hilliard-Brinkman System

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Communications in Computational Physics 2013年第4期13卷 929-957页

作者： Craig Collins Jie Shen steven m.Wise Department of mathematics University of TennesseeKnoxvilleTN 37912USA Department of mathematics Purdue UniversityWest LafayetteIN 47907USA

We present an unconditionally energy stable and uniquely solvable finite difference scheme for the Cahn-Hilliard-Brinkman(CHB)system,which is comprised of a Cahn-Hilliard-type diffusion equation and a generalized Brinkman equation modeling fluid *** CHB system is a generalization of the Cahn-Hilliard-Stokes model and describes two phase very viscous flows in porous *** scheme is based on a convex splitting of the discrete CH energy and is *** equations at the implicit time level are nonlinear,but we prove that they represent the gradient of a strictly convex functional and are therefore uniquely solvable,regardless of time step *** to energy stability,we show that the scheme is stable in the time and space discrete ℓ^(∞)(0,T;H_(h)^(1))and ℓ^(2)(0,T;H_(h)^(2))*** also present an efficient,practical nonlinear multigrid method–comprised of a standard FAS method for the Cahn-Hilliard part,and a method based on the Vanka smoothing strategy for the Brinkman part-for solving these *** particular,we provide evidence that the solver has nearly optimal complexity in typical *** solver is applied to simulate spinodal decomposition of a viscous fluid in a porous medium,as well as to the more general problems of buoyancy-and boundary-driven flows.

关键词： Cahn-Hilliard equation Stokes equations Brinkman equation finite difference methods nonlinear multigrid convex splitting energy stability

A Third Order Accurate in Time,BDF-Type Energy Stable Scheme for the Cahn-Hilliard Equation

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Numerical mathematics(Theory,methods and Applications) 2022年第2期15卷 279-303页

作者： Kelong Cheng Cheng Wang steven m.Wise Yanmei Wu School of Science Southwest University of Science and TechnologyMianyangSichuan 621010P.R.China Department of mathematics The University of MassachusettsNorth DartmouthMA 02747USA Department of mathematics The University of TennesseeKnoxvilleTN 37996USA

In this paper we propose and analyze a backward differentiation formula(BDF)type numerical scheme for the Cahn-Hilliard equation with third order temporal *** Fourier pseudo-spectral method is used to discretize *** surface diffusion and the nonlinear chemical potential terms are treated implicitly,while the expansive term is approximated by a third order explicit extrapolation formula for the sake of *** addition,a third order accurate Douglas-Dupont regularization term,in the form of−A_(0)△t^(2)△_( N)(φ^(n+1)−φ^(n)),is added in the numerical *** particular,the energy stability is carefully derived in a modified version,so that a uniform bound for the original energy functional is available,and a theoretical justification of the coefficient A becomes *** a result of this energy stability analysis,a uniform-in-time L_(N)^(6)bound of the numerical solution is *** also,the optimal rate convergence analysis and error estimate are provided,in the L_(△t)^(∞)(0,T;L_(N)^(2))∩L^(2)_(△ t)(0,T;H_(h)^(2))norm,with the help of the L_(N)^(6)bound for the numerical solution.A few numerical simulation results are presented to demonstrate the efficiency of the numerical scheme and the third order convergence.

关键词： Cahn-Hilliard equation third order backward differentiation formula unique solvability energy stability discrete L6 N estimate optimal rate convergence analysis

minimally invasive and open gallbladder cancer resections: 30-vs 90-day mortality

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Hepatobiliary & Pancreatic Diseases International 2017年第4期16卷 405-411页

作者： Naeem Goussous motahar Hosseini Anne m Sill steven C Cunningham Department of Surgery Saint Agnes HospitalBaltimoreMDUSA

BACKGROUND:minimally invasive surgery is increasingly used for gallbladder cancer *** mortality at 30 days is low,but 90-day mortality is ***:Using National Cancer Database(1998-2012),all resection patients were ***-and 90-day mortality rates were ***:A total of 36 067 patients were identified,19 139(53%) of whom underwent *** age was 71 years and 70.7% were ***-day mortality following surgical resection was 2.3-fold higher than 30-mortality(17.1% vs 7.4%).There was a statistically significant increase in 30-and 90-day mortality with poorly differentiated tumors,presence of lymphovascular invasion,tumor stage,incomplete surgical resection and low-volume centers(Pminimally invasive resection between 2010 and 2012,the 90-day mortality was 2.8-fold higher than the 30-day mortality(12.0% vs 4.3%).CONCLUSIONS:Ninety-day mortality following gallbladder cancer resection is significantly higher than 30-day *** mortality is associated with tumor grade,lymphovascular invasion,tumor stage,type and completeness of surgical resection as well as type and volume of facility.

关键词： gallbladder cancer laparoscopic minimally invasive survival radical cholecystectomy complications

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metabolic pathways as possible therapeutic targets for progressive multiple sclerosis

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Neural Regeneration Research 2017年第8期12卷 1262-1267页

作者： Rebecca m.Heidker mitchell R.Emerson steven m.Le Vine Department of molecular and Integrative Physiology University of Kansas Medical Center Department of Pharmaceutical Sciences College of Pharmacy-Glendale Midwestern University

Unlike relapsing remitting multiple sclerosis, there are very few therapeutic options for patients with progressive forms of multiple sclerosis. While immune mechanisms are key participants in the pathogenesis of relapsing remitting multiple sclerosis, the mechanisms underlying the development of progressive multiple sclerosis are less well understood. Putative mechanisms behind progressive multiple sclerosis have been put forth： insufficient energy production via mitochondrial dysfunction, activated microglia, iron accumulation, oxidative stress, activated astrocytes, Wallerian degeneration, apoptosis, etc. Furthermore, repair processes such as remyelination are incomplete. Experimental therapies that strive to improve metabolism within neurons and glia, e.g., oligodendrocytes, could act to counter inadequate energy supplies and/or support remyelination. most experimental approaches have been examined as standalone interventions; however, it is apparent that the biochemical steps being targeted are part of larger pathways, which are further intertwined with other metabolic pathways. Thus, the potential benefits of a tested intervention, or of an established therapy, e.g., ocrelizumab, could be undermined by constraints on upstream and/or downstream steps. If correct, then this argues for a more comprehensive, multifaceted approach to therapy. Here we review experimental approaches to support neuronal and glial metabolism, and/or promote remyelination, which may have potential to lessen or delay progressive multiple sclerosis.

关键词： acetyl-coenzyme A carboxylase biotin estrogen iron Kynurenine pathway mitochondria thyroidhormone remyelination stem cells vitamin D

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Phenotypic plasticity in prostate cancer： role of ntrinsically disordered proteins

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Asian Journal of Andrology 2016年第5期18卷 704-710页

作者： steven m mooney mohit Kumar Jolly Herbert Levine Prakash Kulkarni Department of Biology University of Waterloo Waterloo ON N2L 3G1 Canada Center for Theoretical Biological Physics Rice University Houston TX 77005 USA Department of Bioengineering Rice University Houston TX 77005 USA Department of Physics and Astronomy Rice University Houston TX 77005 USA institute for Bioscience and Biotechnology Research University of Maryland Rockville Maryland 20850 USA

A striking characteristic of cancer ceLls is their remarkable phenotypic plasticity, which is the ability to switch states or phenotypes in response to environmental fluctuations. Phenotypic changes such as a partial or complete epithelial to mesenchymal transition （EmT） that play important roles in their survival and proliferation, and development of resistance to therapeutic treatments, are widely believed to arise due to somatic mutations in the genome. However, there is a growing concern that such a deterministic view is not entirely consistent with multiple lines of evidence, which indicate that stochasticity may also play an important role in driving phenotypic plasticity. Here, we discuss how stochasticity in protein interaction networks （PINs） may play a key role in determining phenotypic plasticity in prostate cancer （PCa）. Specifically, we point out that the key players driving transitions among different phenotypes （epithelial, mesenchymal, and hybrid epithelial/mesenchymal）, including ZEB1, SNAIl, OVOL1, and OVOL2, are intrinsically disordered proteins （IDPs） and discuss how plasticity at the molecular level may contribute to stochasticity in phenotypic switching by rewiring PINs. We conclude by suggesting that targeting iDPs implicated in EmT in PCa may be a new strategy to gain additional insights and develop novel treatments for this disease, which is the most common form of cancer in adult men.

关键词： epithelial to mesenchymal transition intrinsically disordered proteins prostate cancer state-switching

Evolution of Strigolactone Perception by Seeds of Parasitic Plants： Reinventing the Wheel

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molecular Plant 2016年第4期9卷 493-495页

作者： Xiong, Guosheng Li, Jiayang Smith, steven m. Chinese Acad Agr Sci Agr Genom Inst Shenzhen Shenzhen 518124 Peoples R China Chinese Acad Sci State Key Lab Plant Genom Inst Genet & Dev Biol Beijing 100101 Peoples R China Chinese Acad Sci Natl Ctr Plant Gene Res Beijing Inst Genet & Dev Biol Beijing 100101 Peoples R China Univ Tasmania Sch Biol Sci Hobart Tas 7001 Australia

A BEWITCHING PROCESS The root-parasitic plants of the witchweed family （Orobanchan- ceae） produce seeds that are adapted to germinate in response to strigolactones （SLs） exuded from the roots of their host plants. The resulting colonization of crops such as maize and sorghum by these parasites can cause massive losses in production and to the livelihoods of farmers （Westwood et al., 2010）.

关键词： root-parasitic plants witchweed

Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism

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Insect Science 2016年第5期23卷 695-703页

作者： Kathleen m Kneeland steven R. Skoda John E. Foster Department of Entomology 103 Entomology Haft University of Nebraska-Lincoln Lincoln NE 68583 USDA-ARS-KBUSLIRL Screwworm Research Unit 2700 Fredericksburg Road Kern/ille TX 78028 USA

The stable fly, Stomoxys calcitrans （L.）（Diptera： muscidae）, is a blood-feeding, economically important pest of animals and humans worldwide. Improved management strategies are essential and their development would benefit from studies on genetic di- versity of stable flies. Especially if done on a global scale, such research could generate information necessary for the development and application of more efficient control meth- ods. Herein we report on a genetic study of stable flies using amplified fragment length polymorphism, with samples of 10-40 individuals acquired from a total of 25 locations in the Nearctic, Neotropic, Palearctic, Afrotropic and Australasian biogeographical regions. We hypothesized that genetic differentiation would exist across geographical barriers. Although Fsx （0.33） was moderately high, the Gsx （0.05; representing genetic diversity between individuals） was very low; Nm values （representing gene flow） were high （9.36）. The mismatch distribution and tests of neutrality suggested population expansion, with no genetic differentiation between locations. The analysis of molecular variance （AmOVA） results showed the majority of genetic diversity was within groups. The mantel test showed no correlation between geographic and genetic distance; this strongly supports the AmOVA results. These results suggest that stable flies did not show genetic differentiation but are panmictic, with no evidence of isolation by distance or across geographical barriers.

关键词： AFLP biting flies external parasites genetic diversity livestock pests Stomoxys calcitrans

Distributed sparse bundle adjustment algorithm based on three-dimensional point partition and asynchronous communication

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Frontiers of Information Technology & Electronic Engineering 2018年第7期19卷 889-904页

作者： Xiao-long SHEN Yong DOU steven mILLS David m EYERS Huan FENG Zhiyi HUANG College of Computer National University of Defense Technology Science and Technology on Parallel and Distributed Laboratory National University of Defense Technology Department of Computer Science University of Otago Department of Computer Science Tsinghua University

Sparse bundle adjustment(SBA) is a key but time-and memory-consuming step in three-dimensional(3 D) reconstruction. In this paper, we propose a 3 D point-based distributed SBA algorithm(DSBA) to improve the speed and scalability of SBA. The algorithm uses an asynchronously distributed sparse bundle adjustment(A-DSBA)to overlap data communication with equation computation. Compared with the synchronous DSBA mechanism(SDSBA), A-DSBA reduces the running time by 46%. The experimental results on several 3 D reconstruction datasets reveal that our distributed algorithm running on eight nodes is up to five times faster than that of the stand-alone parallel SBA. Furthermore, the speedup of the proposed algorithm(running on eight nodes with 48 cores) is up to41 times that of the serial SBA(running on a single node).

关键词： Sparse bundle adjustment Parallel Distributed sparse bundle adjustment Three-dimensional reconstruction Asynchronous

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mate choice decisions by searchers

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Current Zoology 2013年第2期59卷 184-199页

作者： Daniel D. WIEGmANN Lisa m. ANGELONI steven m. SEUBERT J. GordonWADE Department of Biological Sciences and J. P. Scott Center for Neuroscience Mind and Behavior Bowling Green State University Bowling Green OH 43403 USA Department of Biology Colorado State University Fort Collins CO 80523 USA Department of mathematics and Statistics Bowling Green State University Bowling Green OH 43403 USA

For more than two decades rudimentary versions of the fixed sample and sequential search strategies have provided the primary theoretical foundation for the study of mate choice decisions by searchers. The theory that surrounds these models has expanded markedly over this time period. In this paper, we review and extend results derived from these models, with a focus on the empirical analysis of searcher behavior. The basic models are impractical for empirical purposes because they rely on the as- sumption that searchers--and, for applied purposes, researchers--assess prospective mates based on their quality, the fitness consequences of mate choice decisions. Here we expound versions of the models that are more empirically useful, reformulated to reflect decisions based on male phenotypic characters. For some organisms, it may be possible to use preference functions to de- rive predictions from the reformulated models and thereby avoid difficulties associated with the measurement of male quality per se. But predictions derived from the two models are difficult to differentiate empirically, regardless of how the models are formu- lated. Here we develop ideas that illustrate how this goal might be accomplished. In addition, we clarify how the variability of male quality should be evaluated and we extend what is known about how this variability influences searcher behavior under each model. more general difficulties associated with the empirical study of mate choice decisions by searchers are also discussed [Current Zoology 59 （2）： 184-199, 2013].

关键词： Dispersive order Fixed sample strategy mate choice Preference functions Sequential search Stochastic dominance