Stability and Time-Step Constraints of Implicit-Explicit Runge-Kutta Methods for the Linearized Korteweg-de Vries Equation

This paper provides a study on the stability and time-step constraints of solving the linearized Korteweg-de Vries(KdV)equation,using implicit-explicit(IMEX)Runge-Kutta(RK)time integration methods combined with either finite difference(FD)or local discontinuous Galerkin(DG)spatial discretization.We analyze the stability of the fully discrete scheme,on a uniform mesh with periodic boundary conditions,using the Fourier method.For the linearized KdV equation,the IMEX schemes are stable under the standard Courant-Friedrichs-Lewy(CFL)conditionτ≤λh.Here,λis the CFL number,τis the time-step size,and h is the spatial mesh size.We study several IMEX schemes and characterize their CFL number as a function ofθ=d/h^(2)with d being the dispersion coefficient,which leads to several interesting observations.We also investigate the asymptotic behaviors of the CFL number for sufficiently refined meshes and derive the necessary conditions for the asymptotic stability of the IMEX-RK methods.Some numerical experiments are provided in the paper to illustrate the performance of IMEX methods under different time-step constraints.

Mathematical Modeling of Cell Polarity Establishment of Budding Yeast

The budding yeast Saccharomyces cerevisiae is a powerful model system for studying the cell polarity establishment.The cell polarization process is regulated by signaling molecules,which are initially distributed in the cytoplasm and then recruited to a proper location on the cell membrane in response to spatial cues or spontaneously.Polarization of these signaling molecules involves complex regulation,so the mathematical models become a useful tool to investigate the mechanism behind the process.In this review,we discuss how mathematical modeling has shed light on different regulations in the cell polarization.We also propose future applications for the mathematical modeling of cell polarization and morphogenesis.

Nonuniform Dependence on the Initial Data for Solutions of Conservation Laws

In this paper,we study systems of conservation laws in one space dimension.We prove that for classical solutions in Sobolev spaces H^(s),with s>3/2,the data-to-solution map is not uniformly continuous.Our results apply to all nonlinear scalar conservation laws and to nonlinear hyperbolic systems of two equations.

Imprinting at the KBTBD6 locus involves species-specific m ternal methylation and monoallelic expression in livestock animals

Background The primary differentially methylated regions(DMRs) which are maternally hypermethylated serve as imprinting control regions(ICRs) that drive monoallelic gene expression, and these ICRs have been investigated due to their implications in mammalian development. Although a subset of genes has been identified as imprinted, in-depth comparative approach needs to be developed for identification of species-specific imprinted genes. Here, we examined DNA methylation status and allelic expression at the KBTBD6 locus across species and tissues and explored potential mechanisms of imprinting.Results Using whole-genome bisulfite sequencing and RNA-sequencing on parthenogenetic and normal porcine embryos, we identified a maternally hypermethylated DMR between the embryos at the KBTBD6 promoter Cp G island and paternal monoallelic expression of KBTBD6. Also, in analyzed domesticated mammals but not in humans, non-human primates and mice, the KBTBD6 promoter Cp G islands were methylated in oocytes and/or allelically methyl-ated in tissues, and monoallelic KBTBD6 expression was observed, indicating livestock-specific imprinting. Further analysis revealed that these Cp G islands were embedded within transcripts in porcine and bovine oocytes which coexisted with an active transcription mark and DNA methylation, implying the presence of transcription-dependent imprinting.Conclusions In this study, our comparative approach revealed an imprinted expression of the KBTBD6 gene in domesticated mammals, but not in humans, non-human primates, and mice which implicates species-specific evolution of genomic imprinting.

Ocular syphilis:a case series of four patients and a review of the literature

Background:The incidence of syphilis has been increasing in the United States over the last two decades,with a more recent increase among women.Ocular syphilis is an uncommon but important complication of syphilis,most often presenting as posterior or panuveitis in late or latent syphilis of unknown duration.Untreated ocular syphilis may lead to permanent vision loss,underscoring the importance of appropriate evaluation and treatment of ocular syphilis.Case Description:In a retrospective,non-contiguous case series,we highlight four patients diagnosed and treated with ocular syphilis at a single institution.Four presentations of ocular syphilis are illustrated:anterior and intermediate uveitis,optic neuritis,posterior uveitis,and panuveitis.All patients initially presented with a decreased visual acuity(VA).One patient had a previous diagnosis of human immunodeficiency virus(HIV).Three patients were treated with intravenous(IV)penicillin and one patient with IV ceftriaxone.All had a return to their baseline VA after their course of treatment.Conclusions:Syphilis may go undetected without a high index of clinical suspicion due to its nonspecific presentations.All patients with ocular inflammation should have syphilis testing as a part of their infectious workup with both treponemal and non-treponemal testing.Patients diagnosed with syphilis and are not known to be HIV-negative should undergo testing for HIV due to the high rate of co-infection.Early diagnosis and prompt treatment after onset of symptoms may contribute to a more favorable prognosis for ocular syphilis.

Using Crop Management Scenario Simulations to Evaluate the Sensitivity of the Ohio Phosphorus Risk Index

Phosphorus (P) risk indices are commonly used in the USA to estimate the field-scale risk of agricultural P runoff. Because the Ohio P Risk Index is increasingly being used to judge farmer performance, it is important to evaluate weighting/scoring of all P Index parameters to ensure Ohio farmers are credited for practices that reduce P runoff risk and not unduly penalized for things not demonstrably related to runoff risk. A sensitivity analysis provides information as to how sensitive the P Index score is to changes in inputs. The objectives were to determine 1) which inputs are most highly associated with P Index scores and 2) the relative impact of each input variable on resultant P Index scores. The current approach uses simulations across 6134 Ohio point locations and five crop management scenarios (CMSs), representing increasing soil disturbance. The CMSs range from all no-till, which is being promoted in Ohio, rotational tillage, which is a common practice in Ohio to full tillage to represent an extreme practice. Results showed that P Index scores were best explained by soil test P (31.9%) followed by connectivity to water (29.7%), soil erosion (13.4%), fertilizer application amount (11.3%), runoff class (9.5%), fertilizer application method (2.2%), and finally filter strip (2.0%). Ohio P Index simulations across CMSs one through five showed that >40% scored <15 points (low) while <1.5% scored >45 points (very high). Given Ohio water quality problems, the Ohio P Index needs to be stricter. The current approach is useful for Ohio P Index evaluations and revision decisions by spatially illustrating the impact of potential changes regionally and state-wide.

Bimodal grain structure formation and strengthening mechanisms in Mg-Mn-Al-Ca extrusion alloys

The effects of small additions of calcium (0.1%and 0.5%~1) on the dynamic recrystallization behavior and mechanical properties of asextruded Mg-1Mn-0.5Al alloys were investigated.Calcium microalloying led to the formation of Al_(2)Ca in as-cast Mg-1Mn-0.5Al-0.1Ca alloy and both Mg_(2)Ca and Al_(2)Ca phases in Mg-1Mn-0.5Al-0.5Ca alloy.The formed Al_(2)Ca particles were fractured during extrusion process and distributed at grain boundary along extrusion direction (ED).The Mg_(2)Ca phase was dynamically precipitated during extrusion process,hindering dislocation movement and reducing dislocation accumulation in low angle grain boundaries (LAGBs) and hindering the transformation of high density of LAGBs into high angle grain boundaries (HAGBs).Therefore,a bimodal structure composed of fine dynamically recrystallized (DRXed) grains and coarse un DRXed regions was formed in Ca-microalloyed Mg-1Mn-0.5Al alloys.The bimodal structure resulted in effective hetero-deformation-induced (HDI) strengthening.Additionally,the fine grains in DRXed regions and the coarse grains in un DRXed regions and the dynamically precipitated Mg_(2)Ca phase significantly enhanced the tensile yield strength from 224 MPa in Mg-1Mn-0.5Al to335 MPa and 352 MPa in Mg-1Mn-0.5Al-0.1Ca and Mg-1Mn-0.5Al-0.5Ca,respectively.Finally,a yield point phenomenon was observed in as-extruded Mg-1Mn-0.5Al-x Ca alloys,more profound with 0.5%Ca addition,which was due to the formation of (■) extension twins in un DRXed regions.

New unexpected role for Wolfram Syndrome protein WFS1:a novel therapeutic target for Alzheimer’s disease?

Selective vulnerability of excitatory neurons in Alzheimer’s disease(AD):AD is the most common form of dementia;however,the pathogenesis of AD is largely unknown.One of the characteristic features of AD is the formation of intracellular neurofibrillary tangles(NFTs).NFTs are abnormal accumulates of misfolded tau protein,which may eventually cause neuronal death and neurodegeneration(Jack et al.,2018).In the early stages of AD progression,not all neurons are equally vulnerable to tau aggregates.Previous studies have shown that large pyramidal neurons in the entorhinal cortex(EC)are specifically vulnerable to pathological tau accumulation(Fu et al.,2017).This selective vulnerability of excitatory neurons to tau pathology is one of the fundamental questions needed to be answered in AD research.

Multi-targeted anti-inflammatory drugs for the treatment of neurological disorders

Inflammation and kinase pathophysiology in neurological disorders:Inflammation is one of the common features of various acute and degenerative neurological disorders,such as stroke,traumatic brain injury(TBI),Alzheimer’s disease(AD),Parkinson’s disease(PD),and others.The inflammatory responses are manifested as the synthesis of inflammation mediators,recruitment of leukocytes,and other secondary injuries.Compelling evidence shows that a large number of inflammation mediators(e.g.,thrombin,reactive oxygen species,cytokines,chemokines,and other molecules)are implicated in the pathophysiological processes in neurological disorders(Liu and Ander,2012)(Figure 1).These increased inflammation mediators stimulate their downstream transmembrane receptors(e.g.,protease-activated receptors,cytokine receptors,and others),and further activate the intracellular downstream effector kinases,such as Src family kinase,Rho-associated protein kinase,Jun N-terminal kinase,extracellular signal-regulated kinase,cyclin-dependent kinase(CDK),and others(Liu and Ander,2012)(Figure 1).Aside from overlapping in different neurological disorders,numerous inflammatory molecules and multiple kinase-involved signaling pathways can be linked to a single neurological disorder such as AD(Heneka et al.,2015).Because of their pivot roles in the process of inflammation,kinases have been regarded as anti-inflammatory targets to improve outcomes of neurological disorders.

Non-exercise estimated cardiorespiratory fitness and cancer incidence:The NIH-AARP diet and health study

Background Non-exercise estimated cardiorespiratory fitness(NEE-CRF)has been shown to be associated with mortality,although its association with cancer incidence is unknown.The study aimed to assess the prospective association between NEE-CRF and cancer incidence in a large cohort of men and women.Methods The National Institutes of Health-American Association of Retired Persons diet and health study is a prospective cohort that included 402,548 participants aged 50–71 years who were free from cancer at baseline(1995–1996)(men(n=238,835)and women(n=163,713))and were followed until December 31,2015.The exposure variable was NEE-CRF expressed in metabolic equivalents.NEE-CRF was estimated using a validated equation of self-reported predictors on demographics and lifestyle behaviors derived from baseline questionnaires.Primary outcomes were total cancer incidence and incidence of prostate,breast,lung,and colorectal cancers.Cox proportional hazards models were analyzed for the association between NEE-CRF and cancer incidence outcomes adjusted for established cancer risk factors.Results During 13.7±3.2 years of follow-up(mean±SD),64,344 men and 31,315 women developed a new cancer.For every 1-metabolic equivalent higher NEE-CRF,the hazard ratios and 95%confidence intervals(95%CIs)were 0.96(95%CI:0.94–0.97)and 0.88(95%CI:0.84–0.92)of total and colorectal cancer incidence among men,and 0.95(95%CI:0.93–0.97)and 0.94(95%CI:0.91–0.97)of total and breast cancer incidence among women,respectively(all p<0.001).NEE-CRF was not associated with incidence of prostate and lung cancers in men or colorectal and lung cancers in women.Conclusion These results suggest that higher CRF levels,as assessed by the applied non-exercise estimated method,may provide preventive benefits against the development of cancer,while low CRF could potentially serve as a modifiable cancer risk factor.Integrating NEE-CRF into screening paradigms and referring low-fit individuals to improve CRF could complement the public health prevention strategy against cancer.

Enhancing corrosion resistance of ZK60 magnesium alloys via Ca microalloying: The impact of nanoscale precipitates

Enhancing corrosion resistance of Mg-Zn alloys with high strength and low cost was critical for broadening their large-scale practical applications. Here we prepared solutionized, peak-and over-aged ZK60 alloys with and without microalloying Ca(0.26 wt.%) to explore the effects of nanoscale precipitates on their corrosion behavior in detail via experimental analyses and theoretical calculations. The results suggested the peak-aged ZK60 alloy with Ca addition showed improved corrosion resistance in comparison with the alloys without Ca,owing to the contribution of Ca on the refinement of precipitates and increase in their number density. Although the precipitates and Mg matrix formed micro-galvanic couples leading to dissolution, the fine and dense precipitates could generate “in-situ pinning” effect on the corrosion products, forming a spider-web-like structure and improving the corrosion inhibition ability accordingly. The pinning effect was closely related to the size and number density of precipitates. This study provided important insight into the design and development of advanced corrosion resistant Mg alloys.

Rural implementation of the perioperative surgical home:A case-control study

BACKGROUND Perioperative surgical home(PSH)is a novel patient-centric surgical system developed by American Society of Anesthesiologist to improve outcomes and patient satisfaction.PSH has proven success in large urban health centers by reducing surgery cancellation,operating room time,length of stay(LOS),and readmission rates.Yet,only limited studies have assessed the impact of PSH on surgical outcomes in rural areas.AIM To evaluate the newly implemented PSH system at a community hospital by comparing the surgical outcomes using a longitudinal case-control study.METHODS The research study was conducted at an 83-bed,licensed level-III trauma rural community hospital.A total of 3096 TJR procedures were collected retrospectively between January 2016 and December 2021 and were categorized as PSH and non-PSH cohorts(n=2305).To evaluate the importance of PSH in the rural surgical system,a case-control study was performed to compare TJR surgical outcomes(LOS,discharge disposition,and 90-d readmission)of the PSH cohort against two control cohorts[Control-1 PSH(C1-PSH)(n=1413)and Control-2 PSH(C2-PSH)(n=892)].Statistical tests including Chi-square test or Fischer’s exact test were performed for categorical variables and Mann-Whitney test or Student’s t-test were performed for continuous variables.The general linear models(Poisson regression and binomial logistic regression)were performed to fit adjusted models.RESULTS The LOS was significantly shorter in PSH cohort compared to two control cohorts(median PSH=34 h,C1-PSH=53 h,C2-PSH=35 h)(P value<0.05).Similarly,the PSH cohort had lower percentages of discharges to other facilities(PSH=3.5%,C1-PSH=15.5%,C2-PSH=6.7%)(P value<0.05).There was no statistical difference observed in 90-d readmission between control and PSH cohorts.However,the PSH implementation reduced the 90-d readmission percentage(PSH=4.7%,C1-PSH=6.1%,C2-PSH=3.6%)lower than the national average 30-d readmission percentage which is 5.5%.The PSH system was effectively established at the rural community hospital with the help of team-based coordinated multi-disciplinary clinicians or physician comanagement.The elements of PSH including preoperative assessment,patient education and optimization,and longitudinal digital engagement were vital for improving the TJR surgical outcomes at the community hospital.CONCLUSION Implementation of the PSH system in a rural community hospital reduced LOS,increased directto-home discharge,and reduced 90-d readmission percentages.

The 17th Workshop on Antarctic Meteorology and Climate and 7th Year of Polar Prediction in the Southern Hemisphere Meeting

1.Overview August 2022 marked the 17th Workshop on Antarctic Meteorology and Climate(WAMC)which was held in a hybrid format at the Pyle Center at the University of Wisconsin-Madison(UW-Madison)in Madison,WI,USA.The workshop is the first partial in-person gathering since the 14th WAMC(Lazzara et al.,2018)as the 15th WAMC was canceled due to the COVID-19 pandemic,and the 16th WAMC(Bromwich et al.,2022)was purely online.Global members of the Antarctic meteorological community gathered at this meeting to present and discuss weather-related topics encompassing scientific research and support operations within Antarctic meteorology and climate.These conversations aimed to share and discuss results,future developments,and build collaborative plans.

通过添加微量Mn元素激活非基面滑移提高镁合金塑性

分析微量锰添加对镁合金显微组织和力学性能的影响。采用电子背散射技术、迹线分析、透射电镜和粘塑性自洽模拟等方法研究变形过程中的塑性变形机理。结果表明:Mn的加入使Mg−Mn合金的平均晶粒尺寸由28.30μm减小到5.10μm;同时,随着Mn含量的增加,样品的断裂伸长率由14.33%提高到20.33%,屈服强度则由84 MPa提高到180 MPa。这种同时提高塑性和强度的原因是基面滑移和非基面滑移之间的临界剪切应力差从173 MPa减小到115 MPa,导致非基面滑移活动明显增加。通过微合金元素调整滑移系统差异为开发具有高强度和延展性的镁合金提供了一种途径。

Extreme Weather Disruptions and Emergency Preparedness Among Older Adults in Ohio: An Eight-County Assessment

The disproportionate risks and impacts of climate change and extreme weather on older adults are increasingly evident. While especially true in disaster-prone areas, human-caused climate change introduces an element of uncertainty even in previously identified “safe” regions such as the Midwestern United States. Using a cumulative disadvantage and vulnerability-informed framework and descriptive statistics from multiple data sources, this article provides an overview of climate impacts, vulnerabilities, and county-level characteristics, focusing on older adults living in Central Ohio. A comparative multiple-case study methodology was used to triangulate regionally representative primary and secondary data sources to examine state and county-level measures of vulnerability, emergency preparedness, and disruptions caused by extreme weather among older adults across eight counties in Central Ohio. Seventy-eight percent of older adults in the sample reported being prepared for emergencies per Federal Emergency Management Agency guidelines. Older adults in Union County reported the highest rates of preparedness, while those in Fayette County reported the lowest. County-level rates of disruption of life activities by extreme weather ranged widely. Among the most rural in the region, Fayette County emerged as uniquely disadvantaged, with the lowest median income, the most vulnerable across multiple social vulnerability dimensions, and the most reported disruptions to life activities from extreme weather. County profiles offer a snapshot of existing vulnerabilities, socioeconomic conditions, special needs, preparedness, and current disruptions among older adults in the region and can inform resource mobilization across community and policy contexts.

Data-Driven Modeling of Partially Observed Biological Systems

We present a numerical approach for modeling unknown dynamical systems using partially observed data,with a focus on biological systems with(relatively)complex dynamical behavior.As an extension of the recently developed deep neural network(DNN)learning methods,our approach is particularly suitable for practical situations when(i)measurement data are available for only a subset of the state variables,and(ii)the system parameters cannot be observed or measured at all.We demonstrate that,with a properly designed DNN structure with memory terms,effective DNN models can be learned from such partially observed data containing hidden parameters.The learned DNN model serves as an accurate predictive tool for system analysis.Through a few representative biological problems,we demonstrate that such DNN models can capture qualitative dynamical behavior changes in the system,such as bifurcations,even when the parameters controlling such behavior changes are completely unknown throughout not only the model learning process but also the system prediction process.The learned DNN model effectively creates a“closed”model involving only the observables when such a closed-form model does not exist mathematically.

A Vertex Network Model of Arabidopsis Leaf Growth

Biology provides many examples of complex systems whose properties allow organisms to develop in a highly reproducible,or robust,manner.One such system is the growth and development of flat leaves in Arabidopsis thaliana.This mechanistically challenging process results from multiple inputs including gene interactions,cellular geometry,growth rates,and coordinated cell divisions.To better understand how this complex genetic and cellular information controls leaf growth,we developed a mathematical model of flat leaf production.This two-dimensional model describes the gene interactions in a vertex network of cells which grow and divide according to physical forces and genetic information.Interestingly,the model predicts the presence of an unknown additional factor required for the formation of biologically realistic gene expression domains and iterative cell division.This two-dimensional model will form the basis for future studies into robustness of adaxial-abaxial patterning.

Dynamics of Advantageous Mutant Spread in Spatial Death-Birth and Birth-Death Moran Models

The spread of an advantageous mutation through a population is of fundamental interest in population genetics. While the classical Moran model is formulated for a well-mixed population, it has long been recognized that in real-world applications, the population usually has an explicit spatial structure which can significantly influence the dynamics. In the context of cancer initiation in epithelial tissue, several recent works have analyzed the dynamics of advantageous mutant spread on integer lattices, using the biased voter model from particle systems theory. In this spatial version of the Moran model, individuals first reproduce according to their fitness and then replace a neighboring individual. From a biological standpoint, the opposite dynamics, where individuals first die and are then replaced by a neighboring individual according to its fitness, are equally relevant. Here, we investigate this death-birth analogue of the biased voter model. We construct the process mathematically, derive the associated dual process, establish bounds on the survival probability of a single mutant, and prove that the process has an asymptotic shape. We also briefly discuss alternative birth-death and death-birth dynamics, depending on how the mutant fitness advantage affects the dynamics. We show that birth-death and death-birth formulations of the biased voter model are equivalent when fitness affects the former event of each update of the model, whereas the birth-death model is fundamentally different from the death-birth model when fitness affects the latter event.

Population Dynamics in an Advective Environment

We consider a one-dimensional reaction-diffusion equation describing single-and two-species population dynamics in an advective environment,based on the modeling frameworks proposed by Lutscher et al.in 2006.We analyze the effect of rate of loss of individuals at both the upstream and downstream boundaries.In the single-species case,we prove the existence of the critical domain size and provide explicit formulas in terms of model parameters.We further derive qualitative properties of the critical domain size and show that,in some cases,the critical domain size is either strictly decreasing over all diffusion rates,or monotonically increasing after first decreasing to a minimum.We also consider competition between species differing only in their diffusion rates.For two species having large diffusion rates,we give a sufficient condition to determine whether the faster or slower diffuser wins the competition.We also briefly discuss applications of these results to competition in species whose spatial niche is affected by shifting isotherms caused by climate change.