Crystal growth and solute precipitation is a Stefan problem.It is a free boundary problem for a parabolic partial differential equation with a time-dependent phase interface.The velocity of the moving interface betwee...Crystal growth and solute precipitation is a Stefan problem.It is a free boundary problem for a parabolic partial differential equation with a time-dependent phase interface.The velocity of the moving interface between solute and crystal is a local function. The dendritic structure of the crystal interface,which develops dynamically,requires high resolution of the interface geometry.These facts make the Lagrangian front tracking method well suited for the problem.In this paper,we introduce an upgraded version of the front tracking code and its associated algorithms for the numerical study of crystal formation.We compare our results with the smoothed particle hydrodynamics method(SPH)in terms of the crystal fractal dimension with its dependence on the Damkohler number and density ratio.展开更多
In our recent work (Wang, Burgei, and Zhou, 2018) we studied the hearing loss injury among subjects in a crowd with a wide spectrum of heterogeneous individual injury susceptibility due to biovariability. The injury r...In our recent work (Wang, Burgei, and Zhou, 2018) we studied the hearing loss injury among subjects in a crowd with a wide spectrum of heterogeneous individual injury susceptibility due to biovariability. The injury risk of a crowd is defined as the average fraction of injured. We examined mathematically the injury risk of a crowd vs the number of acoustic impulses the crowd is exposed to, under the assumption that all impulses act independently in causing injury regardless of whether one is preceded by another. We concluded that the observed dose-response relation can be explained solely on the basis of biovariability in the form of heterogeneous susceptibility. We derived an analytical solution for the distribution density of injury susceptibility, as a power series expansion in terms of scaled log individual non-injury probability. While theoretically the power series converges for all argument values, in practical computations with IEEE double precision, at large argument values, the numerical accuracy of the power series summation is completely wiped out by the accumulation of round-off errors. In this study, we derive a general asymptotic approximation at large argument values, for the distribution density. The combination of the power series and the asymptotics provides a practical numerical tool for computing the distribution density. We then use this tool to verify numerically that the distribution obtained in our previous theoretical study is indeed a proper density. In addition, we will also develop a very efficient and accurate Pade approximation for the distribution density.展开更多
The present work concerns the momentum and heat transmission of the electro-magnetohydrodynamic (E-MHD) boundary layer Darcy-Forchheimer flow of a Sutterby fluid over a linear stretching sheet with slip. The nonlinear...The present work concerns the momentum and heat transmission of the electro-magnetohydrodynamic (E-MHD) boundary layer Darcy-Forchheimer flow of a Sutterby fluid over a linear stretching sheet with slip. The nonlinear equations for the proposed model are analyzed numerically. Suitable techniques are used to transform the coupled nonlinear partial differential equations (PDEs) conforming to the forced balance law, energy, and concentration equations into a nonlinear coupled system of ordinary differential equations (ODEs). Numerical solutions of the transformed nonlinear system are obtained using a shooting method, improved by the Cash and Carp coefficients. The influence of important physical variables on the velocity, the temperature, the heat flux coefficient, and the skin-friction coefficient is verified and analyzed through graphs and tables. From the comprehensive analysis of the present work, it is concluded that by intensifying the magnitude of the Hartmann number, the momentum distribution decays, whereas the thermal profile of fluid increases. Furthermore, it is also shown that by aug- menting the values of the momentum slip parameter, the velocity profile diminishes. It is found that the Sutterby fluid model shows shear thickening and shear thinning behaviors. The momentum profile shows that the magnitude of velocity for the shear thickening case is dominant as compared with the shear thinning case. It is also demonstrated that the Sutterby fluid model reduces to a Newtonian model by fixing the fluid parameter to zero. In view of the limiting case, it is established that the surface drag in the case of the Sutterby model shows a trifling pattern as compared with the classical case.展开更多
In this article,the rheology of Ferro-fluid over an axisymmetric heated disc with a variable magnetic field by considering the dispersion of hybrid nanoparticles is considered.The flow is assumed to be produced by the...In this article,the rheology of Ferro-fluid over an axisymmetric heated disc with a variable magnetic field by considering the dispersion of hybrid nanoparticles is considered.The flow is assumed to be produced by the stretching of a rotating heated disc.The contribution of variable thermophysical properties is taken to explore themomentum,mass and thermal transportation.The concept of boundary layermechanismis engaged to reduce the complex problem into a simpler one in the form of coupled partial differential equations system.The complex coupled PDEs are converted into highly nonlinear coupled ordinary differential equations system(ODEs)and the resulting nonlinear flow problem is handled numerically.The solution is obtained via finite element procedure(FEP)and convergence is established by conducting the grid-independent survey.The solution of converted dimensionless problem containing fluid velocity,temperature and concentration field is plotted against numerous involved emerging parameters and their impact is noted.From the obtained solution,it is monitored that higher values of magnetic parameter retard the fluid flow and escalating values of Eckert number results in to enhance temperature profile.Ferro-fluid flow and heat energy for the case of the Yamada Ota hybrid model are higher than for the case of the Hamilton Crosser hybrid model.Developing a model is applicable to the printing process,electronic devices,temperature measurements,engineering process and food-making process.The amount of mass species is reduced vs.incline impacts of chemical reaction and Schmidt parameter.展开更多
BACKGROUND Integrative multi-omic approaches have been increasingly applied to discovery and functional studies of complex human diseases.Short-term preoperative antibiotics have been adopted to reduce site infections...BACKGROUND Integrative multi-omic approaches have been increasingly applied to discovery and functional studies of complex human diseases.Short-term preoperative antibiotics have been adopted to reduce site infections in colorectal cancer(CRC)resections.We hypothesize that the antibiotics will impact analysis of multi-omic datasets generated from resection samples to investigate biological CRC risk factors.AIM To assess the impact of preoperative antibiotics and other variables on integrated microbiome and human transcriptomic data generated from archived CRC resection samples.METHODS Genomic DNA(gDNA)and RNA were extracted from prospectively collected 51 pairs of frozen sporadic CRC tumor and adjacent non-tumor mucosal samples from 50 CRC patients archived at a single medical center from 2010-2020.The 16S rRNA gene sequencing(V3V4 region,paired end,300 bp)and confirmatory quantitative polymerase chain reaction(qPCR)assays were conducted on gDNA.RNA sequencing(IPE,125 bp)was performed on parallel tumor and non-tumor RNA samples with RNA Integrity Numbers scores≥6.RESULTS PERMANOVA detected significant effects of tumor vs nontumor histology(P=0.002)and antibiotics(P=0.001)on microbialβ-diversity,but CRC tumor location(left vs right),diabetes mellitus vs not diabetic and Black/African Ancestry(AA)vs not Black/AA,did not reach significance.Linear mixed models detected significant tumor vs nontumor histology*antibiotics interaction terms for 14 genus level taxa.QPCR confirmed increased Fusobacterium abundance in tumor vs nontumor groups,and detected significantly reduced bacterial load in the(+)antibiotics group.Principal coordinate analysis of the transcriptomic data showed a clear separation between tumor and nontumor samples.Differentially expressed genes obtained from separate analyses of tumor and nontumor samples,are presented for the antibiotics,CRC location,diabetes and Black/AA race groups.CONCLUSION Recent adoption of additional preoperative antibiotics as standard of care,has a measurable impact on-omics analysis of resected specimens.This study still confirmed increased Fusobacterium nucleatum in tumor.展开更多
Background:As type 2 diabetes mellitus(T2DM)biomarkers,branched-chain amino acids(BCAAs:valine,leucine and isoleucine)and aromatic amino acids(AAAs:phenylalanine,tryptophan and tyrosine)may be correlated with the occu...Background:As type 2 diabetes mellitus(T2DM)biomarkers,branched-chain amino acids(BCAAs:valine,leucine and isoleucine)and aromatic amino acids(AAAs:phenylalanine,tryptophan and tyrosine)may be correlated with the occurrence and development of T2DM.However,there is still no consensus on the disperse and isolated biomarkers of T2DM.Purpose:To explore the correlation between amino acids and T2DM based on integrated biomarker approach revealed.Methods:PubMed,Web of Science and CNKI were selected to search the literature published until August 31,2019.The included studies described the association between BCAAs,AAAs and T2DM.Random effect model and fixed effect model were adopted in pooled analysis to determine mean difference and 95 percent confidence interval of metabolites.Integrated biomarker was constructed in form of concentration change ratios or risk ratio(RR),relative risk(HR)and odds ratio(OR)of BCAAs and AAAs to reflect the integrated change information of amino acids.Results:The selected 20 studies contained 14942 healthy individuals and 3615 T2DM patients.The levels of BCAAs,phenylalanine and tyrosine both in plasma and serum samples were increased among all T2DM patients compared with those of the healthy control subjects(P<0.00001).However,the mean difference of tryptophan concentration was not statistically significant(P=0.60).The concentration change ratios or HR/RR/OR of BCAAs and AAAs were connected to form integrated biomarker.Conclusion:The integrated biomarker including BCAAs and AAAs could reflect the basic characteristics of T2DM,which has the potential clinical value on comprehensive diagnosis of T2DM.展开更多
In today’s digital world,the most inevitable challenge is the protection of digital information.Due to the weak confidentiality preserving techniques,the existing world is facing several digital information breaches.T...In today’s digital world,the most inevitable challenge is the protection of digital information.Due to the weak confidentiality preserving techniques,the existing world is facing several digital information breaches.To make our digital data indecipherable to the unauthorized person,a technique forfinding a crypto-graphically strong Substitution box(S-box)have presented.An S-box with sound cryptographic assets such as nonlinearity(NL),strict avalanche criterion(SAC),bit independence criteria(BIC),bit independence criteria of nonlinearity(BIC-NL),Bit independence criteria of Strict avalanche criteria(BIC-SAC),and Input/output XOR is considered as the robust S-box.The Decision-Making Trial and Evaluation Laboratory(DEMATEL)approach of multi-criteria decision making(MCDM)is proposed forfinding the interrelation among cryptographic properties.A combination of two MCDM methods namely Entropy and multi-objective optimization based on ratio analysis(MOORA)is applied for the best S-box selection.A robust substitution box is selected for secure communications in cryptography by using the combination of DEMETAL selection criteria,entro-py weight assigning,and MOORA ranking scheme.The combination of these three methods provides a fast selection procedure for the secure confusion com-ponent.The offered selection method can also be utilized for the choice of the best cryptosystem with highly secure properties and resistive against all possible linear and differential attacks in the cryptanalysis.展开更多
Humans are able to overcome sensory perturbations imposed on their movements through motor learning. One of the key mechanisms to accomplish this is sensorimotor adaptation, an implicit, error-driven learning mechanis...Humans are able to overcome sensory perturbations imposed on their movements through motor learning. One of the key mechanisms to accomplish this is sensorimotor adaptation, an implicit, error-driven learning mechanism. Past work on sensorimotor adaptation focused mainly on adaptation to rotated visual feedback—A paradigm known as visuomotor rotation. Recent studies have shown that sensorimotor adaptation can also occur under mirror-reversed visual feedback. In visuomotor rotation, sensorimotor adaptation can be driven by both endpoint and online feedback [1] [2]. However, it’s not been clear whether both kinds of feedback can similarly drive adaptation under a mirror reversed perturbation. We performed a study to establish what kinds of feedback can drive adaptation under mirror reversal. In the first two conditions, the participants were asked to ignore visual feedback. In the first condition, we provided mirror reversed online feedback and endpoint feedback. We reproduced previous findings showing that online feedback elicited adaptation under mirror reversal. In a second condition, we provided mirror reversed endpoint feedback. However, in the second condition, we found that endpoint feedback alone failed to elicit adaptation. In a third condition, we provided both types of feedback at the same time, but in a conflicting way: endpoint feedback was non-reversed while online feedback was mirror reversed. The participants were asked to ignore online visual feedback and try to hit the target with help from veridical endpoint feedback. In the third condition, in which veridical endpoint feedback and mirror reversed online feedback were provided, adaptation still occurred. Our results showed that endpoint feedback did not elicit adaptation under mirror reversal but online feedback did. This dissociation between effects of endpoint feedback and online feedback on adaptation under mirror reversal suggests that adaptation under these different kinds of feedback might in fact operate via distinct mechanisms.展开更多
Hearing loss is a common military health problem and it is closely related to exposures to impulse noises from blast explosions and weapon firings. In a study based on test data of chinchillas and scaled to humans (Mi...Hearing loss is a common military health problem and it is closely related to exposures to impulse noises from blast explosions and weapon firings. In a study based on test data of chinchillas and scaled to humans (Military Medicine, 181: 59-69), an empirical injury model was constructed for exposure to multiple sound impulses of equal intensity. Building upon the empirical injury model, we conduct a mathematical study of the hearing loss injury caused by multiple impulses of non-uniform intensities. We adopt the theoretical framework of viewing individual sound exposures as separate injury causing events, and in that framework, we examine synergy for causing injury (fatigue) or negative synergy (immunity) or independence among a sequence of doses. Starting with the empirical logistic dose-response relation and the empirical dose combination rule, we show that for causing injury, a sequence of sound exposure events are not independent of each other. The phenomenological effect of a preceding event on the subsequent event is always immunity. We extend the empirical dose combination rule, which is applicable only in the case of homogeneous impulses of equal intensity, to accommodate the general case of multiple heterogeneous sound exposures with non-uniform intensities. In addition to studying and extending the empirical dose combination rule, we also explore the dose combination rule for the hypothetical case of independent events, and compare it with the empirical one. We measure the effect of immunity quantitatively using the immunity factor defined as the percentage of decrease in injury probability attributed to the sound exposure in the preceding event. Our main findings on the immunity factor are: 1) the immunity factor is primarily a function of the difference in SELA (A- weighted sound exposure level) between the two sound exposure events;it is virtually independent of the magnitude of the two SELA values as long as the difference is fixed;2) the immunity factor increases monotonically from 0 to 100% as the first dose is varied from being significantly below the second dose, to being moderately above the second dose. The extended dose-response formulation developed in this study provides a theoretical framework for assessing the injury risk in realistic situations.展开更多
We consider the hearing loss injury among subjects in a crowd with a wide spectrum of individual intrinsic injury probabilities due to biovariability. For multiple acoustic impulses, the observed injury risk of a crow...We consider the hearing loss injury among subjects in a crowd with a wide spectrum of individual intrinsic injury probabilities due to biovariability. For multiple acoustic impulses, the observed injury risk of a crowd vs the effective combined dose follows the logistic dose-response relation. The injury risk of a crowd is the average fraction of injured. The injury risk was measured in experiments as follows: each subject is individually exposed to a sequence of acoustic impulses of a given intensity and the injury is recorded;results of multiple individual subjects were assembled into data sets to mimic the response of a crowd. The effective combined dose was adjusted by varying the number of impulses in the sequence. The most prominent feature observed in experiments is that the injury risk of the crowd caused by multiple impulses is significantly less than the value predicted based on assumption that all impulses act independently in causing injury and all subjects in the crowd are statistically identical. Previously, in the case where all subjects are statistically identical (i.e., no biovariability), we interpreted the observed injury risk caused by multiple impulses in terms of the immunity effects of preceding impulses on subsequent impulses. In this study, we focus on the case where all sound exposure events act independently in causing injury regardless of whether one is preceded by another (i.e., no immunity effect). Instead, we explore the possibility of interpreting the observed logistic dose-response relation in the framework of biovariability of the crowd. Here biovariability means that subjects in the crowd have their own individual injury probabilities. That is, some subjects are biologically less or more susceptible to hearing loss injury than others. We derive analytically the distribution of individual injury probability that produces the observed logistic dose-response relation. For several parameter values, we prove that the derived distribution is mathematically a proper density function. We further study the asymptotic approximations for the density function and discuss their significance in practical numerical computation with finite precision arithmetic. Our mathematical analysis implies that the observed logistic dose-response relation can be theoretically explained in the framework of biovariability in the absence of immunity effect.展开更多
The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella(1998,J. Comput.Phys.147,60)has been extended for elliptic and pa...The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella(1998,J. Comput.Phys.147,60)has been extended for elliptic and parabolic problems with interior boundaries or interfaces of discontinuities of material properties or solutions.Second order accuracy is achieved in space and time for both stationary and moving interface problems. The method is conservative for elliptic and parabolic problems with fixed interfaces.Based on this method,a front tracking algorithm for the Stefan problem has been developed. The accuracy of the method is measured through comparison with exact solution to a two-dimensional Stefan problem.The algorithm has been used for the study of melting and solidification problems.展开更多
This paper investigates the effect of launching multiple weapons against an area target of normally distributed elements. We provide an analytical form of the average damage fraction and then apply it to obtain optima...This paper investigates the effect of launching multiple weapons against an area target of normally distributed elements. We provide an analytical form of the average damage fraction and then apply it to obtain optimal aimpoints. To facilitate the computational efforts in practice, we also consider optimizations over given constrained patterns of aimpoints. Finally, we derive scaling laws for optimal aimpoints and optimal damage fraction with respect to the radius of the area target.展开更多
Background and Aims: The incidence and mortality of colorectal cancer is persistently highest in Black/African-Americans in the United States. While access to care, barriers to screening, and poverty might explain the...Background and Aims: The incidence and mortality of colorectal cancer is persistently highest in Black/African-Americans in the United States. While access to care, barriers to screening, and poverty might explain these findings, there in increased interest in examining biological factors that impact the colonic environment. Our group is examining biologic factors that contribute to disparities in development of adenomas prospectively. In preparation for this and to characterize a potential patient population, we conducted a retrospective review of initial screening colonoscopies in a cohort of patients. Methods: A retrospective review was performed on initial average risk screening colonoscopies on patients (age 45 - 75 years) during 2012 at three institutions. Descriptive statistics and multivariable logistic regression models were used to examine the relationship between potential risk factors and the detection of adenomas. Results: Of the 2225 initial screening colonoscopies 1495 (67.2%) were performed on Black/African-Americans and 566 (25.4%) on Caucasians. Multivariable logistic regression revealed that older age, male sex, current smoking and teaching gastroenterologists were associated with higher detection of adenomas and these were less prevalent among Black/African-Americas except for age. Neither race, ethnicity, BMI, diabetes mellitus, HIV nor insurance was associated with adenoma detection. Conclusion: In this sample, there was no association between race and adenoma detection. While this may be due to a lower prevalence of risk factors for adenomas in this sample, our findings were confounded by a lower detection rate by consultant gastroenterologists at one institution. The study allowed us to rectify the problem and characterize patients for future trials.展开更多
Abstract We study the damage probability when M weapons are used against a unitary target. We use the Carleton damage function to model the distribution of damage probability caused by each weapon. The deviation of th...Abstract We study the damage probability when M weapons are used against a unitary target. We use the Carleton damage function to model the distribution of damage probability caused by each weapon. The deviation of the impact point from the aimpoint is attributed to both the dependent error and independent errors. The dependent error is one random variable affecting M weapons the same way while independent errors are associated with individual weapons and are independent of each other. We consider the case where the dependent error is significant, non-negligible relative to independent errors. We first derive an explicit exact solution for the damage probability caused by M weapons for any M. Based on the exact solution, we find the optimal aimpoint distribution of M weapons to maximize the damage probability in several cases where the aimpoint distribution is constrained geometrically with a few free parameters, including uniform distributions around a circle or around an ellipse. Then, we perform unconstrained optimization to obtain the overall optimal aimpoint distribution and the overall maximum damage probability, which is carried out for different values of M, up to 20 weapons. Finally, we derive a phenomenological approximate expression for the damage probability vs. M, the number of weapons, for the parameters studied here.展开更多
We investigated the motions associated with prices for futures contracts within financial markets.We aimed to derive the market prices from the physics approach.We used the projectile motion models defined under two d...We investigated the motions associated with prices for futures contracts within financial markets.We aimed to derive the market prices from the physics approach.We used the projectile motion models defined under two distinct conditions(perfect/horizontal and imperfect/drag implication)based on Newton’s and Galileo’s laws of motion.In addition,we applied the simple harmonic oscillatory model to present the movements of prices from the market equilibrium position.Despite that it was more theoretical,we managed to derive the futures price functions and the results showed that futures prices depend largely on market forces of demand and supply and underlying assets price behaviour.Also,we managed to find the terminal prices for the securities given the initial prices,which are a worrying matter to the trading parties.The equilibrium price analysis was done and the simple harmonic model proved to be efficient in such modelling.We managed to identify the price motions to and from the equilibrium point with markets.Results suggested that it is the market frictions(market forces of demand and supply)that propel prices to move.Also,we noted that these forces are responsible for bringing back the prices at equilibrium if the market is left to operate as free.Nevertheless,from the performance comparison of the two models used,results suggested that futures price function from a drag variable is more powerful in modelling the price behaviour for options than the one sorely controlled by market demand and supply forces.And the simple harmonic oscillator model is good at modelling the equilibrium movements of asset prices.Above all,we used the mean absolute deviation(MAD)to validate our futures derivative pricing model.Fortunately,the obtained MAD results supported the efficiency of our model.However,it should not be carelessly taken that the projectile models used are much good at price motions/movements within the market from time to time with a stunted ability to capture in other facts of interest,such as volatility coefficients which pave a research way for other scholars.展开更多
Black box functions, such as computer experiments, often have multiple optima over the input space of the objective function. While traditional optimization routines focus on finding a single best optimum, we sometime...Black box functions, such as computer experiments, often have multiple optima over the input space of the objective function. While traditional optimization routines focus on finding a single best optimum, we sometimes want to consider the relative merits of multiple optima. First we need a search algorithm that can identify multiple local optima. Then we consider that blindly choosing the global optimum may not always be best. In some cases, the global optimum may not be robust to small deviations in the inputs, which could lead to output values far from the optimum. In those cases, it would be better to choose a slightly less extreme optimum that allows for input deviation with small change in the output;such an optimum would be considered more robust. We use a Bayesian decision theoretic approach to develop a utility function for selecting among multiple optima.展开更多
BACKGROUND The Black/African Ancestry(AA)population has a higher prevalence of type 2 diabetes mellitus(T2DM)and a higher incidence and mortality rate for colorectal cancer(CRC)than all other races in the United State...BACKGROUND The Black/African Ancestry(AA)population has a higher prevalence of type 2 diabetes mellitus(T2DM)and a higher incidence and mortality rate for colorectal cancer(CRC)than all other races in the United States.T2DM has been shown to increase adenoma risk in predominantly white/European ancestry(EA)populations,but the effect of T2DM on adenoma risk in Black/AA individuals is less clear.We hypothesize that T2DM has a significant effect on adenoma risk in a predominantly Black/AA population.AIM To investigate the effect of T2DM and race on the adenoma detection rate(ADR)in screening colonoscopies in two disparate populations.METHODS A retrospective cohort study was conducted on ADR during index screening colonoscopies(age 45-75)performed at an urban public hospital serving a predominantly Black/AA population(92%)(2017-2018,n=1606).Clinical metadata collected included basic demographics,insurance,body mass index(BMI),family history of CRC,smoking,diabetes diagnosis,and aspirin use.This dataset was combined with a recently reported parallel retrospective cohort data set collected at a suburban university hospital serving a predominantly White/EA population(87%)(2012-2015,n=2882).RESULTS The ADR was higher in T2DM patients than in patients without T2DM or prediabetes(35.2%vs 27.9%,P=0.0166,n=981)at the urban public hospital.Multivariable analysis of the combined datasets showed that T2DM[odds ratio(OR)=1.29,95%confidence interval(CI):1.08-1.55,P=0.0049],smoking(current vs never OR=1.47,95%CI:1.18-1.82,current vs past OR=1.32,95%CI:1.02-1.70,P=0.0026),older age(OR=1.05 per year,95%CI:1.04-1.06,P<0.0001),higher BMI(OR=1.02 per unit,95%CI:1.01-1.03,P=0.0003),and male sex(OR=1.87,95%CI:1.62-2.15,P<0.0001)were associated with increased ADR in the combined datasets,but race,aspirin use and insurance were not.CONCLUSION T2DM,but not race,is significantly associated with increased ADR on index screening colonoscopy while controlling for other factors.展开更多
On July 3-4,2018,an international workshop was organised at the University of Cambridge,by Dr.Nikoforakis,to mark the 80th anniversary of a young scientist,Philip Roe.Phil's scientific achievements are numerous,an...On July 3-4,2018,an international workshop was organised at the University of Cambridge,by Dr.Nikoforakis,to mark the 80th anniversary of a young scientist,Philip Roe.Phil's scientific achievements are numerous,and it is quite difficult to adequately address his accomplishments in a short preface.Phil began his journey at Cambridge,first for his Bachelor's degree and then obtaining his Master's degree in 1962.He left for the Royal Aircraft Establishment(RAE)between 1962 to 1984 to work as an engineer.It was a period of adventure,and the design of mature CFD codes for solving the Euler equations was far from being achieved.Though the Lax-Wendroff theorem was known(published in 1960),as for many novelties,it had taken some time before it became a gold standard.At the RAE,Phil was assigned by his manager to work in a direction that eventually led to Roe's Riemann solver and flux.This method is now standard in every specialised textbook,but the jump from generalizing the Murman scheme for Euler equations to what is now commonly known as the Roe flux is far from obvious.Phil Roe relates this adventure,and others,in his"scientific autobiography",one of the papers of this focused issue.展开更多
基金supported in part by the ITAPS Award from US Department of Energy DEFC0206ER25770the ARO Award W911NF0910306+1 种基金supported in part by the DOE subaward through RPI with the Prime Award DEFG0707ID14889supported in part by NSF Award DMS0809285
文摘Crystal growth and solute precipitation is a Stefan problem.It is a free boundary problem for a parabolic partial differential equation with a time-dependent phase interface.The velocity of the moving interface between solute and crystal is a local function. The dendritic structure of the crystal interface,which develops dynamically,requires high resolution of the interface geometry.These facts make the Lagrangian front tracking method well suited for the problem.In this paper,we introduce an upgraded version of the front tracking code and its associated algorithms for the numerical study of crystal formation.We compare our results with the smoothed particle hydrodynamics method(SPH)in terms of the crystal fractal dimension with its dependence on the Damkohler number and density ratio.
文摘In our recent work (Wang, Burgei, and Zhou, 2018) we studied the hearing loss injury among subjects in a crowd with a wide spectrum of heterogeneous individual injury susceptibility due to biovariability. The injury risk of a crowd is defined as the average fraction of injured. We examined mathematically the injury risk of a crowd vs the number of acoustic impulses the crowd is exposed to, under the assumption that all impulses act independently in causing injury regardless of whether one is preceded by another. We concluded that the observed dose-response relation can be explained solely on the basis of biovariability in the form of heterogeneous susceptibility. We derived an analytical solution for the distribution density of injury susceptibility, as a power series expansion in terms of scaled log individual non-injury probability. While theoretically the power series converges for all argument values, in practical computations with IEEE double precision, at large argument values, the numerical accuracy of the power series summation is completely wiped out by the accumulation of round-off errors. In this study, we derive a general asymptotic approximation at large argument values, for the distribution density. The combination of the power series and the asymptotics provides a practical numerical tool for computing the distribution density. We then use this tool to verify numerically that the distribution obtained in our previous theoretical study is indeed a proper density. In addition, we will also develop a very efficient and accurate Pade approximation for the distribution density.
文摘The present work concerns the momentum and heat transmission of the electro-magnetohydrodynamic (E-MHD) boundary layer Darcy-Forchheimer flow of a Sutterby fluid over a linear stretching sheet with slip. The nonlinear equations for the proposed model are analyzed numerically. Suitable techniques are used to transform the coupled nonlinear partial differential equations (PDEs) conforming to the forced balance law, energy, and concentration equations into a nonlinear coupled system of ordinary differential equations (ODEs). Numerical solutions of the transformed nonlinear system are obtained using a shooting method, improved by the Cash and Carp coefficients. The influence of important physical variables on the velocity, the temperature, the heat flux coefficient, and the skin-friction coefficient is verified and analyzed through graphs and tables. From the comprehensive analysis of the present work, it is concluded that by intensifying the magnitude of the Hartmann number, the momentum distribution decays, whereas the thermal profile of fluid increases. Furthermore, it is also shown that by aug- menting the values of the momentum slip parameter, the velocity profile diminishes. It is found that the Sutterby fluid model shows shear thickening and shear thinning behaviors. The momentum profile shows that the magnitude of velocity for the shear thickening case is dominant as compared with the shear thinning case. It is also demonstrated that the Sutterby fluid model reduces to a Newtonian model by fixing the fluid parameter to zero. In view of the limiting case, it is established that the surface drag in the case of the Sutterby model shows a trifling pattern as compared with the classical case.
文摘In this article,the rheology of Ferro-fluid over an axisymmetric heated disc with a variable magnetic field by considering the dispersion of hybrid nanoparticles is considered.The flow is assumed to be produced by the stretching of a rotating heated disc.The contribution of variable thermophysical properties is taken to explore themomentum,mass and thermal transportation.The concept of boundary layermechanismis engaged to reduce the complex problem into a simpler one in the form of coupled partial differential equations system.The complex coupled PDEs are converted into highly nonlinear coupled ordinary differential equations system(ODEs)and the resulting nonlinear flow problem is handled numerically.The solution is obtained via finite element procedure(FEP)and convergence is established by conducting the grid-independent survey.The solution of converted dimensionless problem containing fluid velocity,temperature and concentration field is plotted against numerous involved emerging parameters and their impact is noted.From the obtained solution,it is monitored that higher values of magnetic parameter retard the fluid flow and escalating values of Eckert number results in to enhance temperature profile.Ferro-fluid flow and heat energy for the case of the Yamada Ota hybrid model are higher than for the case of the Hamilton Crosser hybrid model.Developing a model is applicable to the printing process,electronic devices,temperature measurements,engineering process and food-making process.The amount of mass species is reduced vs.incline impacts of chemical reaction and Schmidt parameter.
基金National Cancer Institute,No.P20 CA192994National Cancer Institute,No.P20 CA192996Simons Foundation,No.415604。
文摘BACKGROUND Integrative multi-omic approaches have been increasingly applied to discovery and functional studies of complex human diseases.Short-term preoperative antibiotics have been adopted to reduce site infections in colorectal cancer(CRC)resections.We hypothesize that the antibiotics will impact analysis of multi-omic datasets generated from resection samples to investigate biological CRC risk factors.AIM To assess the impact of preoperative antibiotics and other variables on integrated microbiome and human transcriptomic data generated from archived CRC resection samples.METHODS Genomic DNA(gDNA)and RNA were extracted from prospectively collected 51 pairs of frozen sporadic CRC tumor and adjacent non-tumor mucosal samples from 50 CRC patients archived at a single medical center from 2010-2020.The 16S rRNA gene sequencing(V3V4 region,paired end,300 bp)and confirmatory quantitative polymerase chain reaction(qPCR)assays were conducted on gDNA.RNA sequencing(IPE,125 bp)was performed on parallel tumor and non-tumor RNA samples with RNA Integrity Numbers scores≥6.RESULTS PERMANOVA detected significant effects of tumor vs nontumor histology(P=0.002)and antibiotics(P=0.001)on microbialβ-diversity,but CRC tumor location(left vs right),diabetes mellitus vs not diabetic and Black/African Ancestry(AA)vs not Black/AA,did not reach significance.Linear mixed models detected significant tumor vs nontumor histology*antibiotics interaction terms for 14 genus level taxa.QPCR confirmed increased Fusobacterium abundance in tumor vs nontumor groups,and detected significantly reduced bacterial load in the(+)antibiotics group.Principal coordinate analysis of the transcriptomic data showed a clear separation between tumor and nontumor samples.Differentially expressed genes obtained from separate analyses of tumor and nontumor samples,are presented for the antibiotics,CRC location,diabetes and Black/AA race groups.CONCLUSION Recent adoption of additional preoperative antibiotics as standard of care,has a measurable impact on-omics analysis of resected specimens.This study still confirmed increased Fusobacterium nucleatum in tumor.
基金supported by the National Natural Science Foundation of China(grant number 81773891)the National Great New Drugs Development Project of China(grant number 2017ZX09301-040)the Beijing Municipal Science and Technology Commission(grant number XMLX201704,2018-2-2242,7194280).
文摘Background:As type 2 diabetes mellitus(T2DM)biomarkers,branched-chain amino acids(BCAAs:valine,leucine and isoleucine)and aromatic amino acids(AAAs:phenylalanine,tryptophan and tyrosine)may be correlated with the occurrence and development of T2DM.However,there is still no consensus on the disperse and isolated biomarkers of T2DM.Purpose:To explore the correlation between amino acids and T2DM based on integrated biomarker approach revealed.Methods:PubMed,Web of Science and CNKI were selected to search the literature published until August 31,2019.The included studies described the association between BCAAs,AAAs and T2DM.Random effect model and fixed effect model were adopted in pooled analysis to determine mean difference and 95 percent confidence interval of metabolites.Integrated biomarker was constructed in form of concentration change ratios or risk ratio(RR),relative risk(HR)and odds ratio(OR)of BCAAs and AAAs to reflect the integrated change information of amino acids.Results:The selected 20 studies contained 14942 healthy individuals and 3615 T2DM patients.The levels of BCAAs,phenylalanine and tyrosine both in plasma and serum samples were increased among all T2DM patients compared with those of the healthy control subjects(P<0.00001).However,the mean difference of tryptophan concentration was not statistically significant(P=0.60).The concentration change ratios or HR/RR/OR of BCAAs and AAAs were connected to form integrated biomarker.Conclusion:The integrated biomarker including BCAAs and AAAs could reflect the basic characteristics of T2DM,which has the potential clinical value on comprehensive diagnosis of T2DM.
基金funded by Princess Nourah bint Abdulrahman University Researchers Supporting Project Number(PNURSP2022R87),Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia.
文摘In today’s digital world,the most inevitable challenge is the protection of digital information.Due to the weak confidentiality preserving techniques,the existing world is facing several digital information breaches.To make our digital data indecipherable to the unauthorized person,a technique forfinding a crypto-graphically strong Substitution box(S-box)have presented.An S-box with sound cryptographic assets such as nonlinearity(NL),strict avalanche criterion(SAC),bit independence criteria(BIC),bit independence criteria of nonlinearity(BIC-NL),Bit independence criteria of Strict avalanche criteria(BIC-SAC),and Input/output XOR is considered as the robust S-box.The Decision-Making Trial and Evaluation Laboratory(DEMATEL)approach of multi-criteria decision making(MCDM)is proposed forfinding the interrelation among cryptographic properties.A combination of two MCDM methods namely Entropy and multi-objective optimization based on ratio analysis(MOORA)is applied for the best S-box selection.A robust substitution box is selected for secure communications in cryptography by using the combination of DEMETAL selection criteria,entro-py weight assigning,and MOORA ranking scheme.The combination of these three methods provides a fast selection procedure for the secure confusion com-ponent.The offered selection method can also be utilized for the choice of the best cryptosystem with highly secure properties and resistive against all possible linear and differential attacks in the cryptanalysis.
文摘Humans are able to overcome sensory perturbations imposed on their movements through motor learning. One of the key mechanisms to accomplish this is sensorimotor adaptation, an implicit, error-driven learning mechanism. Past work on sensorimotor adaptation focused mainly on adaptation to rotated visual feedback—A paradigm known as visuomotor rotation. Recent studies have shown that sensorimotor adaptation can also occur under mirror-reversed visual feedback. In visuomotor rotation, sensorimotor adaptation can be driven by both endpoint and online feedback [1] [2]. However, it’s not been clear whether both kinds of feedback can similarly drive adaptation under a mirror reversed perturbation. We performed a study to establish what kinds of feedback can drive adaptation under mirror reversal. In the first two conditions, the participants were asked to ignore visual feedback. In the first condition, we provided mirror reversed online feedback and endpoint feedback. We reproduced previous findings showing that online feedback elicited adaptation under mirror reversal. In a second condition, we provided mirror reversed endpoint feedback. However, in the second condition, we found that endpoint feedback alone failed to elicit adaptation. In a third condition, we provided both types of feedback at the same time, but in a conflicting way: endpoint feedback was non-reversed while online feedback was mirror reversed. The participants were asked to ignore online visual feedback and try to hit the target with help from veridical endpoint feedback. In the third condition, in which veridical endpoint feedback and mirror reversed online feedback were provided, adaptation still occurred. Our results showed that endpoint feedback did not elicit adaptation under mirror reversal but online feedback did. This dissociation between effects of endpoint feedback and online feedback on adaptation under mirror reversal suggests that adaptation under these different kinds of feedback might in fact operate via distinct mechanisms.
基金The project supported by the National Natural Science Foundation of China (10272067, 10426024)the Doctoral Program Foundation of the Education Ministry of China (20030422046)the Natural Science Foundation of Shandong University at Weihai.
文摘Hearing loss is a common military health problem and it is closely related to exposures to impulse noises from blast explosions and weapon firings. In a study based on test data of chinchillas and scaled to humans (Military Medicine, 181: 59-69), an empirical injury model was constructed for exposure to multiple sound impulses of equal intensity. Building upon the empirical injury model, we conduct a mathematical study of the hearing loss injury caused by multiple impulses of non-uniform intensities. We adopt the theoretical framework of viewing individual sound exposures as separate injury causing events, and in that framework, we examine synergy for causing injury (fatigue) or negative synergy (immunity) or independence among a sequence of doses. Starting with the empirical logistic dose-response relation and the empirical dose combination rule, we show that for causing injury, a sequence of sound exposure events are not independent of each other. The phenomenological effect of a preceding event on the subsequent event is always immunity. We extend the empirical dose combination rule, which is applicable only in the case of homogeneous impulses of equal intensity, to accommodate the general case of multiple heterogeneous sound exposures with non-uniform intensities. In addition to studying and extending the empirical dose combination rule, we also explore the dose combination rule for the hypothetical case of independent events, and compare it with the empirical one. We measure the effect of immunity quantitatively using the immunity factor defined as the percentage of decrease in injury probability attributed to the sound exposure in the preceding event. Our main findings on the immunity factor are: 1) the immunity factor is primarily a function of the difference in SELA (A- weighted sound exposure level) between the two sound exposure events;it is virtually independent of the magnitude of the two SELA values as long as the difference is fixed;2) the immunity factor increases monotonically from 0 to 100% as the first dose is varied from being significantly below the second dose, to being moderately above the second dose. The extended dose-response formulation developed in this study provides a theoretical framework for assessing the injury risk in realistic situations.
文摘We consider the hearing loss injury among subjects in a crowd with a wide spectrum of individual intrinsic injury probabilities due to biovariability. For multiple acoustic impulses, the observed injury risk of a crowd vs the effective combined dose follows the logistic dose-response relation. The injury risk of a crowd is the average fraction of injured. The injury risk was measured in experiments as follows: each subject is individually exposed to a sequence of acoustic impulses of a given intensity and the injury is recorded;results of multiple individual subjects were assembled into data sets to mimic the response of a crowd. The effective combined dose was adjusted by varying the number of impulses in the sequence. The most prominent feature observed in experiments is that the injury risk of the crowd caused by multiple impulses is significantly less than the value predicted based on assumption that all impulses act independently in causing injury and all subjects in the crowd are statistically identical. Previously, in the case where all subjects are statistically identical (i.e., no biovariability), we interpreted the observed injury risk caused by multiple impulses in terms of the immunity effects of preceding impulses on subsequent impulses. In this study, we focus on the case where all sound exposure events act independently in causing injury regardless of whether one is preceded by another (i.e., no immunity effect). Instead, we explore the possibility of interpreting the observed logistic dose-response relation in the framework of biovariability of the crowd. Here biovariability means that subjects in the crowd have their own individual injury probabilities. That is, some subjects are biologically less or more susceptible to hearing loss injury than others. We derive analytically the distribution of individual injury probability that produces the observed logistic dose-response relation. For several parameter values, we prove that the derived distribution is mathematically a proper density function. We further study the asymptotic approximations for the density function and discuss their significance in practical numerical computation with finite precision arithmetic. Our mathematical analysis implies that the observed logistic dose-response relation can be theoretically explained in the framework of biovariability in the absence of immunity effect.
基金supported by the U.S.Department of Energy under Contract No.DE-AC02-98CH10886 and by the State of New York
文摘The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella(1998,J. Comput.Phys.147,60)has been extended for elliptic and parabolic problems with interior boundaries or interfaces of discontinuities of material properties or solutions.Second order accuracy is achieved in space and time for both stationary and moving interface problems. The method is conservative for elliptic and parabolic problems with fixed interfaces.Based on this method,a front tracking algorithm for the Stefan problem has been developed. The accuracy of the method is measured through comparison with exact solution to a two-dimensional Stefan problem.The algorithm has been used for the study of melting and solidification problems.
文摘This paper investigates the effect of launching multiple weapons against an area target of normally distributed elements. We provide an analytical form of the average damage fraction and then apply it to obtain optimal aimpoints. To facilitate the computational efforts in practice, we also consider optimizations over given constrained patterns of aimpoints. Finally, we derive scaling laws for optimal aimpoints and optimal damage fraction with respect to the radius of the area target.
文摘Background and Aims: The incidence and mortality of colorectal cancer is persistently highest in Black/African-Americans in the United States. While access to care, barriers to screening, and poverty might explain these findings, there in increased interest in examining biological factors that impact the colonic environment. Our group is examining biologic factors that contribute to disparities in development of adenomas prospectively. In preparation for this and to characterize a potential patient population, we conducted a retrospective review of initial screening colonoscopies in a cohort of patients. Methods: A retrospective review was performed on initial average risk screening colonoscopies on patients (age 45 - 75 years) during 2012 at three institutions. Descriptive statistics and multivariable logistic regression models were used to examine the relationship between potential risk factors and the detection of adenomas. Results: Of the 2225 initial screening colonoscopies 1495 (67.2%) were performed on Black/African-Americans and 566 (25.4%) on Caucasians. Multivariable logistic regression revealed that older age, male sex, current smoking and teaching gastroenterologists were associated with higher detection of adenomas and these were less prevalent among Black/African-Americas except for age. Neither race, ethnicity, BMI, diabetes mellitus, HIV nor insurance was associated with adenoma detection. Conclusion: In this sample, there was no association between race and adenoma detection. While this may be due to a lower prevalence of risk factors for adenomas in this sample, our findings were confounded by a lower detection rate by consultant gastroenterologists at one institution. The study allowed us to rectify the problem and characterize patients for future trials.
文摘Abstract We study the damage probability when M weapons are used against a unitary target. We use the Carleton damage function to model the distribution of damage probability caused by each weapon. The deviation of the impact point from the aimpoint is attributed to both the dependent error and independent errors. The dependent error is one random variable affecting M weapons the same way while independent errors are associated with individual weapons and are independent of each other. We consider the case where the dependent error is significant, non-negligible relative to independent errors. We first derive an explicit exact solution for the damage probability caused by M weapons for any M. Based on the exact solution, we find the optimal aimpoint distribution of M weapons to maximize the damage probability in several cases where the aimpoint distribution is constrained geometrically with a few free parameters, including uniform distributions around a circle or around an ellipse. Then, we perform unconstrained optimization to obtain the overall optimal aimpoint distribution and the overall maximum damage probability, which is carried out for different values of M, up to 20 weapons. Finally, we derive a phenomenological approximate expression for the damage probability vs. M, the number of weapons, for the parameters studied here.
文摘We investigated the motions associated with prices for futures contracts within financial markets.We aimed to derive the market prices from the physics approach.We used the projectile motion models defined under two distinct conditions(perfect/horizontal and imperfect/drag implication)based on Newton’s and Galileo’s laws of motion.In addition,we applied the simple harmonic oscillatory model to present the movements of prices from the market equilibrium position.Despite that it was more theoretical,we managed to derive the futures price functions and the results showed that futures prices depend largely on market forces of demand and supply and underlying assets price behaviour.Also,we managed to find the terminal prices for the securities given the initial prices,which are a worrying matter to the trading parties.The equilibrium price analysis was done and the simple harmonic model proved to be efficient in such modelling.We managed to identify the price motions to and from the equilibrium point with markets.Results suggested that it is the market frictions(market forces of demand and supply)that propel prices to move.Also,we noted that these forces are responsible for bringing back the prices at equilibrium if the market is left to operate as free.Nevertheless,from the performance comparison of the two models used,results suggested that futures price function from a drag variable is more powerful in modelling the price behaviour for options than the one sorely controlled by market demand and supply forces.And the simple harmonic oscillator model is good at modelling the equilibrium movements of asset prices.Above all,we used the mean absolute deviation(MAD)to validate our futures derivative pricing model.Fortunately,the obtained MAD results supported the efficiency of our model.However,it should not be carelessly taken that the projectile models used are much good at price motions/movements within the market from time to time with a stunted ability to capture in other facts of interest,such as volatility coefficients which pave a research way for other scholars.
文摘Black box functions, such as computer experiments, often have multiple optima over the input space of the objective function. While traditional optimization routines focus on finding a single best optimum, we sometimes want to consider the relative merits of multiple optima. First we need a search algorithm that can identify multiple local optima. Then we consider that blindly choosing the global optimum may not always be best. In some cases, the global optimum may not be robust to small deviations in the inputs, which could lead to output values far from the optimum. In those cases, it would be better to choose a slightly less extreme optimum that allows for input deviation with small change in the output;such an optimum would be considered more robust. We use a Bayesian decision theoretic approach to develop a utility function for selecting among multiple optima.
基金Stony Brook University Targeted Research Opportunity Seed Fusion Grant,No.1135373-3-37298National Cancer Institute,No.P20 CA192994Simons Foundation,No.415604.
文摘BACKGROUND The Black/African Ancestry(AA)population has a higher prevalence of type 2 diabetes mellitus(T2DM)and a higher incidence and mortality rate for colorectal cancer(CRC)than all other races in the United States.T2DM has been shown to increase adenoma risk in predominantly white/European ancestry(EA)populations,but the effect of T2DM on adenoma risk in Black/AA individuals is less clear.We hypothesize that T2DM has a significant effect on adenoma risk in a predominantly Black/AA population.AIM To investigate the effect of T2DM and race on the adenoma detection rate(ADR)in screening colonoscopies in two disparate populations.METHODS A retrospective cohort study was conducted on ADR during index screening colonoscopies(age 45-75)performed at an urban public hospital serving a predominantly Black/AA population(92%)(2017-2018,n=1606).Clinical metadata collected included basic demographics,insurance,body mass index(BMI),family history of CRC,smoking,diabetes diagnosis,and aspirin use.This dataset was combined with a recently reported parallel retrospective cohort data set collected at a suburban university hospital serving a predominantly White/EA population(87%)(2012-2015,n=2882).RESULTS The ADR was higher in T2DM patients than in patients without T2DM or prediabetes(35.2%vs 27.9%,P=0.0166,n=981)at the urban public hospital.Multivariable analysis of the combined datasets showed that T2DM[odds ratio(OR)=1.29,95%confidence interval(CI):1.08-1.55,P=0.0049],smoking(current vs never OR=1.47,95%CI:1.18-1.82,current vs past OR=1.32,95%CI:1.02-1.70,P=0.0026),older age(OR=1.05 per year,95%CI:1.04-1.06,P<0.0001),higher BMI(OR=1.02 per unit,95%CI:1.01-1.03,P=0.0003),and male sex(OR=1.87,95%CI:1.62-2.15,P<0.0001)were associated with increased ADR in the combined datasets,but race,aspirin use and insurance were not.CONCLUSION T2DM,but not race,is significantly associated with increased ADR on index screening colonoscopy while controlling for other factors.
文摘On July 3-4,2018,an international workshop was organised at the University of Cambridge,by Dr.Nikoforakis,to mark the 80th anniversary of a young scientist,Philip Roe.Phil's scientific achievements are numerous,and it is quite difficult to adequately address his accomplishments in a short preface.Phil began his journey at Cambridge,first for his Bachelor's degree and then obtaining his Master's degree in 1962.He left for the Royal Aircraft Establishment(RAE)between 1962 to 1984 to work as an engineer.It was a period of adventure,and the design of mature CFD codes for solving the Euler equations was far from being achieved.Though the Lax-Wendroff theorem was known(published in 1960),as for many novelties,it had taken some time before it became a gold standard.At the RAE,Phil was assigned by his manager to work in a direction that eventually led to Roe's Riemann solver and flux.This method is now standard in every specialised textbook,but the jump from generalizing the Murman scheme for Euler equations to what is now commonly known as the Roe flux is far from obvious.Phil Roe relates this adventure,and others,in his"scientific autobiography",one of the papers of this focused issue.
