mechanisms of coupling in river flow simulation systems integrated modelling approaches for whole river catchments require the coupling of different types of models as an example river flow and forecast models in one and two space dimensions are discussed usually these models are based on the hyperbolic shallow water equations and require special discretizations like eno or godunov type methods the basic coupling mechanisms like coupling via source terms via boundary conditions via state variables and simulator coupling are introduced by examples their properties with respect to performance and accuracy requirements and implementation issues are presented if coupling conditions are considered additional algebraic equations arise by the method of lines approach it is possible to translate the partial differential equations and the algebraic equations into a large system of differential algebraic equations daes the daes can efficiently be solved if the special structure of the jacobian of the coupled model components is taken into account

testing independence for bivariate current status data this article develops a nonparametric procedure for testing marginal independence based on bivariate current status data asymptotic properties of the proposed tests are derived and their finite sample performance is studied via simulations the method is applied to analyze data from a community based study of cardiovascular epidemiology in taiwan

a semi implicit relaxation scheme for modeling two phase flow in a pipeline this work is devoted to the numerical approximation of the solutions to the system of conservation laws which arises in the modeling of two phase flows in pipelines the pdes are closed by two highly nonlinear algebraic relations namely a pressure law and a hydrodynamic law we have previously proposed an explicit relaxation scheme which allows us to cope with these nonlinearities but the system considered has eigenvalues which are of very different orders of magnitude which prevents the explicit scheme from being effective since the time step has to be very small in order to solve this effectiveness problem we now proceed to construct a scheme which is explicit with respect to the small eigenvalues and linearly implicit with respect to the large eigenvalues numerical evidences are provided

optimal system invariant solutions and evolution of weak discontinuity for isentropic drift flux model abstract inequivalent classes of similarity solutions for isentropic drift flux two phase flow model are obtained by using one dimensional optimal classifications the optimality of this classification is shown in a constructive manner i e by constructing various invariant functions including conditional and numerical invariants further with the help of invariant solution we discuss the evolution of weak discontinuity which displays the nature of the general solution

extended symmetry analysis of an isothermal no slip drift flux model abstract we perform extended group analysis for a system of differential equations modeling an isothermal no slip drift flux the maximal lie invariance algebra of this system is proved to be infinite dimensional we also find the complete point symmetry group of this system including discrete symmetries using the megaideal based version of the algebraic method optimal lists of one and two dimensional subalgebras of the maximal lie invariance algebra in question are constructed and employed for obtaining reductions of the system under study since this system contains a subsystem of two equations that involves only two of three dependent variables we also perform group analysis of this subsystem the latter can be linearized by a composition of a fiber preserving point transformation with a two dimensional hodograph transformation to the klein gordon equation we also employ both the linearization and the generalized hodograph method for constructing the general solution of the entire system under study we find inter alia genuinely generalized symmetries for this system and present the connection between them and the lie symmetries of the subsystem we mentioned earlier hydrodynamic conservation laws and their generalizations are also constructed

nonparametric estimation of a markov illness death process from interval censored observations with application to diabetes survival data summary the nonparametric estimation of the cumulative transition intensity functions in a threestate time nonhomogeneous markov process with irreversible transitions an illness death model is considered when times of the intermediate transition e g onset of a disease are interval censored the times of death are assumed to be known exactly or to be rightcensored in addition the observed process may be left truncated data of this type arise when the process is sampled periodically for example when the patients are monitored through periodic examinations the observations on times of change in their disease status will be interval censored under the sampling scheme considered here the nelson aalen estimator aalen 1978 for a cumulative transition intensity is not applicable in the proposed method the maximum likelihood estimators of some of the transition intensities are derived from the estimators of the corresponding subdistribution functions the maximum likelihood estimators are shown to have a self consistency property the self consistency algorithm is developed for the computation of the estimators this approach generalises the results from turnbull 1976 and frydman 1992 the methods are illustrated with diabetes survival data

nonparametric methods for survival sacrifice experiments in many carcinogenicity studies the time to disease occurrence is not clinically observable a survival sacrifice experiment is considered for nonparametric inference about the rate of disease occurrence a multistate model for disease development and death is considered and an algorithm of the em type for maximum likelihood estimation is obtained questions of identifiability and estimability are addressed under the model interval hazards for disease occurrence are identifiable for intervals defined by the sacrifice times a score test is developed appropriate for the comparison of two groups with respect to disease development without need of any assumption concerning lethality of the disease concerned

global existence of weak solutions for a viscous two phase model abstract the purpose of this paper is to explore a viscous two phase liquid gas model relevant for well and pipe flow our approach relies on applying suitable modifications of techniques previously used for studying the single phase isothermal navier stokes equations a main issue is the introduction of a novel two phase variant of the potential energy function needed for obtaining fundamental a priori estimates we derive an existence result for weak solutions in a setting where transition to single phase flow is guaranteed not to occur when the initial state is a true mixture of both phases some numerical examples are also included in order to demonstrate characteristic behavior of solutions in particular we illustrate how two phase flow is genuinely different compared to single phase flow concerning the behavior of an initial mass discontinuity

smooth and discontinuous junctions in the p system abstract consider the p system describing the subsonic flow of a fluid in a pipe with section a a x we prove that the resulting cauchy problem generates a lipschitz semigroup provided the total variation of the initial datum and the oscillation of a are small an explicit estimate on the bound of the total variation of a is provided showing that at lower fluid speeds higher total variations of a are acceptable an example shows that the bound on tv a is mandatory for otherwise the total variation of the solution may grow arbitrarily

nonparametric estimation from current status data with competing risks summary a great deal of recent attention has focused on the estimation of survival distributions based on current status data an extreme form of interval censored data this particular data structure arises in a wide variety of applications where cross sectional observation either naturally occurs or is preferred to more traditional forms of follow up here we consider current status data in the context of competing risks we briefly consider simple parametric models as a backdrop to nonparametric procedures we make some brief comparisons and remarks regarding the nonparametric maximum likelihood estimator the ideas are illustrated on the data of krailo pike 1983 which considers estimation of the age distribution at both natural and operative menopause we also consider the case where there is exact observation of failure times due to one of the competing risks when failure occurs prior to the monitoring time basic techniques of survival analysis focus on estimation of the survival distribution based on various forms of censored data an extreme form of censoring arises where the only information on studied individuals is their survival status at a single monitoring time this particular data structure is known as current status data nonparametric estimation of the survival function and semiparametric techniques for related regression models based on current status data have been much studied of late here we consider estimation of sub survival functions based on current status observations in the presence of competing risks for simplicity we describe only two competing risks but the ideas are easily extended when there are more than two possible causes of failure let j denote the cause specific hazard function for cause j 1 2 kalbfleisch prentice 2002 p 252 if t and j are the random variables that measure time to failure and cause of failure respectively the two sub distribution functions of interest are

the generally covariant locality principle a new paradigm for local quantum field theory a new approach to the model independent description of quantum field theories will be introduced in the present work the main feature of this new approach is to incorporate in a local sense the principle of general covariance of general relativity thus giving rise to the concept of a locally covariant quantum field theory such locally covariant quantum field theories will be described mathematically in terms of covariant functors between the categories on one side of globally hyperbolic spacetimes with isometric embeddings as morphisms and on the other side of algebras with unital injective monomorphisms as morphisms moreover locally covariant quantum fields can be described in this framework as natural transformations between certain functors the usual haag kastler framework of nets of operator algebras over a fixed spacetime background manifold together with covariant automorphic actions of the isometry group of the background spacetime can be re gained from this new approach as a special case examples of this new approach are also outlined in case that a locally covariant quantum field theory obeys the time slice axiom one can naturally associate to it certain automorphic actions called relative cauchy evolutions which describe the dynamical reaction of the quantum field theory to a local change of spacetime background metrics the functional derivative of a relative cauchy evolution with respect to the spacetime metric is found to be a divergence free quantity which has as will be demonstrated in an example the significance of an energy momentum tensor up to addition of scalar functions for the locally covariant quantum field theory furthermore we discuss the functorial properties of state spaces of locally covariant quantum field theories that entail the validity of the principle of local definiteness

the riemann problem for the baer nunziato two phase flow model we consider the riemann problem for the two phase flow model proposed by baer and nunziato int j multiphase flows 12 1986 861 it describes the flame spread and the deflagration to detonation transition ddt in gaspermeable reactive granular materials the model is given by a non strictly hyperbolic non conservative system of partial differential equations we investigate the structure of the riemann problem and construct the exact solution for it we establish that the solution across one wave is not unique and propose to use the evolutionarity criterion to single out the admissible solution due to special structure of the riemann problem for the baer nunziato model we are able to introduce a notion of a weak solution for it finally we propose a number of test cases based on the exact solution to the riemann problem for the baer nunziato model

covariate adjustment of event histories estimated from markov chains the additive approach summary markov chain models are frequently used for studying event histories that include transitions between several states an empirical transition matrix for nonhomogeneous markov chains has previously been developed including a detailed statistical theory based on counting processes and martingales in this article we show how to estimate transition probabilities dependent on covariates this technique may e g be used for making estimates of individual prognosis in epidemiological or clinical studies the covariates are included through nonparametric additive models on the transition intensities of the markov chain the additive model allows for estimation of covariate dependent transition intensities and again a detailed theory exists based on counting processes the martingale setting now allows for a very natural combination of the empirical transition matrix and the additive model resulting in estimates that can be expressed as stochastic integrals and hence their properties are easily evaluated two medical examples will be given in the first example we study how the lung cancer mortality of uranium miners depends on smoking and radon exposure in the second example we study how the probability of being in response depends on patient group and prophylactic treatment for leukemia patients who have had a bone marrow transplantation a program in r and s plus that can carry out the analyses described here has been developed and is freely available on the internet

group classification for isothermal drift flux model of two phase flows in this paper a full symmetry group classification for isothermal multiphase drift flux model is presented all invariant functions are developed for the lie algebra which play a vital role in construction of optimal systems further with the help of one dimensional optimal classification group invariant solutions are obtained which describe the asymptotic behavior of general solution

the analysis of panel data under a markov assumption abstract methods for the analysis of panel data under a continuous time markov model are proposed we present procedures for obtaining maximum likelihood estimates and associated asymptotic covariance matrices for transition intensity parameters in time homogeneous models and for other process characteristics such as mean sojourn times and equilibrium distributions generalizations to handle covariance analysis and to the fitting of certain nonhomogeneous models are presented and an example based on a longitudinal study of the smoking habits of school children is discussed questions of embeddability and estimation are examined

coupling conditions for networked systems of euler equations we are interested in the dynamics of the euler equations on networks we study the situation of a single vertex where the dynamics on the connected arcs are given by the polytropic euler equations such problems arise for example in the context of gas transport in pipe networks for the euler equations in one spatial dimension coupling conditions for the vertex have been proposed recently we present further conditions and introduce a two dimensional representation of the vertex we conduct numerical simulations and compare the obtained results with the theoretical predictions

on linearized coupling conditions for a class of isentropic multiphase drift flux models at pipe to pipe intersections in this paper a general drift flux model describing a subsonic and isentropic multi phase fluid in connected pipes is considered each phase is assumed to be isentropic with its own sonic speed the components are gamma law gases with 1 for such a computational challenge at a junction is the computation of rarefaction waves which do not have a readily available analytical form firstly the well posedness of the riemann problem at the junction is discussed it is suggested that rarefaction waves should be linearized in order to obtain a more efficient numerical method for coupling such multi component flow some computational results on the dynamics of the multi phase gas in the pipes demonstrate the qualitative behavior of this approach

nonparametric maximum likelihood estimation for competing risks survival data subject to interval censoring and truncation we derive the nonparametric maximum likelihood estimate npmle of the cumulative incidence functions for competing risks survival data subject to interval censoring and truncation since the cumulative incidence function npmles give rise to an estimate of the survival distribution which can be undefined over a potentially larger set of regions than the npmle of the survival function obtained ignoring failure type we consider an alternative pseudolikelihood estimator the methods are then applied to data from a cohort of injecting drug users in thailand susceptible to infection from hiv 1 subtypes b and e

maximum likelihood for interval censored data consistency and computation summary standard convex optimization techniques are applied to the analysis of interval censored data these methods provide easily verifiable conditions for the self consistent estimator proposed by turnbull 1976 to be a maximum likelihood estimator and for checking whether the maximum likelihood estimate is unique a sufficient condition is given for the almost sure convergence of the maximum likelihood estimator to the true underlying distribution function

cauchy problem and green s functions for first order differential operators and algebraic quantization existence and uniqueness of advanced and retarded fundamental solutions green s functions and of global solutions to the cauchy problem is proved for a general class of first order linear differential operators on vector bundles over globally hyperbolic lorentzian manifolds this is a core ingredient to car ccr algebraic constructions of quantum field theories on curved spacetimes particularly for higher spin field equations

numerical resolution for a compressible two phase flow model based on the theory of thermodynamically compatible systems this paper is concerned with the numerical solution of the equations governing two phase gas solid mixture in the framework of thermodynamically compatible systems theory the equations constitute a non homogeneous system of nonlinear hyperbolic conservation laws a total variation diminishing tvd slope limiter centre slic numerical scheme based on the splitting approach is presented and applied for the solution of the initial boundary value problem for the equations the model equations and the numerical methods are systematically assessed through a series of numerical test cases strong numerical evidence shows that the model and the methods are accurate robust and conservative the model correctly describes the formations of shocks and rarefactions in two phase gas solid flow

a relaxation method for two phase flow models with hydrodynamic closure law this paper is devoted to the numerical approximation of the solutions of a system of conservation laws arising in the modeling of two phase flows in pipelines the pdes are closed by two highly nonlinear algebraic relations namely a pressure law and a hydrodynamic one the severe nonlinearities encoded in these laws make the classical approximate riemann solvers virtually intractable at a reasonable cost of evaluation we propose a strategy for relaxing solely these two nonlinearities the relaxation system we introduce is of course hyperbolic but all associated eigenfields are linearly degenerate such a property not only makes it trivial to solve the riemann problem but also enables us to enforce some further stability requirements in addition to those coming from a chapman enskog analysis the new method turns out to be fairly simple and robust while achieving desirable positivity properties on the density and the mass fractions extensive numerical evidences are provided

a robust and accurate riemann solver for a compressible two phase flow model in this paper we analyze the riemann problem for the widely used drift flux two phase flow model this analysis introduces the complete information that is attained in the representation of solutions to the riemann problem it turns out that the riemann waves have rarefactions a contact discontinuity and shocks within this respect an exact riemann solver is developed to accurately resolve and represent the complete wave structure of the gas liquid two phase flows to verify the solver a series of test problems selected from the literature are presented including validation against independent numerical simulations where the solution of the riemann problem is fully numerical in this framework the governing equations are discretized by finite volume techniques facilitating the application godunov methods of centred type it is shown that both analytical and numerical results demonstrate the broad applicability and robustness of the new exact riemann solver

global weak solutions for a compressible gas liquid model with well formation interaction abstract the objective of this work is to explore a compressible gas liquid model designed for modeling of well flow processes we build into the model well reservoir interaction by allowing flow of gas between well and formation surrounding reservoir inflow of gas and subsequent expansion of gas as it ascends towards the top of the well a so called gas kick represents a major concern for various well operations in the context of petroleum engineering we obtain a global existence result under suitable assumptions on the regularity of initial data and the rate function that controls the flow of gas between well and formation uniqueness is also obtained by imposing more regularity on the initial data the key estimates are to obtain appropriate lower and upper bounds on the gas and liquid masses for that purpose we introduce a transformed version of the original model that is highly convenient for analysis of the original model in particular in the analysis of the transformed model additional terms representing well formation interaction can be treated by natural extensions of arguments that previously have been employed for the single phase navier stokes model the analysis ensures that transition to single phase regions do not appear when the initial state is a true gas liquid mixture

dirac quantum fields on a manifold on globally hyperbolic lorentzian manifolds we construct field operators which satisfy the dirac equation and have a causal anticommutator ambiguities in the construction are removed by formulating the theory in terms of c algebras of local observables a generalized form of the haag kastler axioms is verified introduction a lorentzian manifold is a four dimensional manifold m together with a pseudo riemannian metric g of signature such manifolds are widely used as models for space time in particular in the absence of boundaries and gravitational fields one uses m r4 and g q minkowski metric which has components ab diag l 1 1 1 we are interested in formulating quantum field theories on general lorentzian manifolds this means giving up many ideas familiar from the usual minkowski space treatments thus there are no poincare transformations on m no vacuum no particle states and so forth all one is left with are the field equations these are to be solved taking as data a representation of the ccr or car over a space like hypersurface ccr canonical commutation relations car canonical anticommutation relations for linear equations this quantum problem can be reduced to a corresponding classical problem for which solutions can be constructed in favorable cases in the nonlinear case very singular formal solutions can be exhibited which one might hope to make rigorous the procedure sketched above is fraught with ambiguities what hypersurface should one take what representation of the ccr car and so forth in general there is no natural choice and one should show that all choices lead to the same theory to do this in a fundamental way it seems necessary to abandon the field operators themselves and instead consider the c algebras that they generate this algebraic approach was originally formulated for minkowski space and seems all the more appropriate here in the haag kastler approach 10 one focuses on the c algebras associated with local regions of space time the algebras of local observables the original formulation on minkowski space consisted of a list of structural properties or axioms which such algebras ought to obey in a recent paper 6 we have proposed a generalization of these axioms to lorentzian manifolds the scalar field was given as an example received by the editors july 23 1980 and in revised form december 11 1980 1980 mathematics subject classification primary 81a17 supported by national science foundation phy77 21740 1982 american mathematical society 0002 9947 82 0000 0 3 12 04 75

on assessing the association for bivariate current status data assuming that the two failure times of interest with bivariate current status data follow a bivariate copula model we propose a two stage estimation procedure to estimate the association parameter which is related to kendall s tau asymptotic properties of the proposed semiparametric estimator show that although the first stage marginal estimators have a convergence rate of only n 1 3 the resulting parameter estimator still converges to a normal random variable with the usual n 1 2 rate the variance of the proposed estimator can be consistently estimated simulation results are presented and a community based study of cardiovascular diseases in taiwan provides an illustrative example

a multiphase godunov method for compressible multifluid and multiphase flows we propose a new model and a solution method for two phase compressible flows the model involves six equations obtained from conservation principles applied to each phase completed by a seventh equation for the evolution of the volume fraction this equation is necessary to close the overall system the model is valid for fluid mixtures as well as for pure fluids the system of partial differential equations is hyperbolic hyperbolicity is obtained because each phase is considered to be compressible two difficulties arise for the solution one of the equations is written in non conservative form non conservative terms exist in the momentum and energy equations we propose robust and accurate discretisation of these terms the method solves the same system at each mesh point with the same algorithm it allows the simulation of interface problems between pure fluids as well as multiphase mixtures several test cases where fluids have compressible behavior are shown as well as some other test problems where one of the phases is incompressible the method provides reliable results is able to compute strong shock waves and deals with complex equations of state

the riemann problem and a high resolution godunov method for a model of compressible two phase flow this paper considers the riemann problem and an associated godunov method for a model of compressible two phase flow the model is a reduced form of the well known baer nunziato model that describes the behavior of granular explosives in the analysis presented here we omit source terms representing the exchange of mass momentum and energy between the phases due to compaction drag heat transfer and chemical reaction but retain the non conservative nozzling terms that appear naturally in the model for the riemann problem the effect of the nozzling terms is confined to the contact discontinuity of the solid phase treating the solid contact as a layer of vanishingly small thickness within which the solution is smooth yields jump conditions that connect the states across the contact as well as a prescription that allows the contribution of the nozzling terms to be computed unambiguously an iterative method of solution is described for the riemann problem that determines the wave structure and the intermediate states of the flow for given left and right states a godunov method based on the solution of the riemann problem is constructed it includes non conservative flux contributions derived from an integral of the nozzling terms over a grid cell the godunov method is extended to second order accuracy using a method of slope limiting and an adaptive riemann solver is described and used for computational efficiency numerical results are presented demonstrating the accuracy of the numerical method and in particular the accurate numerical description of the flow in the vicinity of a solid contact where phases couple and nozzling terms are important the numerical method is compared with other methods available in the literature and found to give more accurate results for the problems considered

a simple construction of recursion operators for multidimensional dispersionless integrable systems abstract we present a simple novel construction of recursion operators for integrable multidimensional dispersionless systems that admit a lax pair whose operators are linear in the spectral parameter and do not involve the derivatives with respect to the latter new examples of recursion operators obtained using our technique include inter alia those for the general heavenly equation which describes a class of anti self dual solutions of the vacuum einstein equations and a six dimensional equation resulting from a system of ferapontov and khusnutdinova

on the modelling and stabilization of flows in networks of open canals in this paper we present a model for the controlled flow of a fluid through a network of canals using a coupled system of st venant equations we then generalize in a variety of ways recent results of coron d andrea novel and bastin concerning the stabilizability around equilibrium of the flow through a single channel this work is based on the theory of quasilinear hyperbolic systems and in particular on a delicate result of li ta tsien concerning the existence and decay of global classical solutions

nonparametric estimation of stage occupation probabilities in a multistage model with current status data multistage models are used to describe individuals or experimental units moving through a succession of stages corresponding to distinct states e g healthy diseased diseased with complications dead the resulting data can be considered to be a form of multivariate survival data containing information about the transition times and the stages occupied traditional survival analysis is the simplest example of a multistage model where individuals begin in an initial stage say alive and move irreversibly to a second stage death in this article we consider general multistage models with a directed tree structure progressive models in which individuals traverse through stages in a possibly non markovian manner we construct nonparametric estimators of stage occupation probabilities and marginal cumulative transition hazards empirical calculations of these quantities are not possible due to the lack of complete data we consider current status information which represents a more severe form of censoring than the commonly used right censoring asymptotic validity of our estimators can be justified using consistency results for nonparametric regression estimators finite sample behavior of our estimators is studied by simulation in which we show that our estimators based on these limited data compare well with those based on complete data we also apply our method to a real life data set arising from a cardiovascular diseases study in taiwan

hadamard states for the linearized yang mills equation on curved spacetime we construct hadamard states for the yang mills equation linearized around a smooth space compact background solution we assume the spacetime is globally hyperbolic and its cauchy surface is compact or equal mathbb r d

monotone nonparametric regression in monotone regression procedures one utilizes only the monotonicity of the regression function in nonparametric regression one utilizes only the assumed smoothness the analytic and asymptotic properties of the estimator are superior in the latter case however monotonicity is not guaranteed we study a hybrid procedure that produces monotone estimators with properties similar to those of nonparametric regression estimators

on the wave interactions in the drift flux equations of two phase flows abstract in the present work we investigate the riemann problem and interaction of weak shocks for the widely used isentropic drift flux equations of two phase flows the complete structure of solution is analyzed and with the help of rankine hugoniot jump condition and lax entropy conditions we establish the existence and uniqueness condition for elementary waves the explicit form of the shock waves contact discontinuities and rarefaction waves are derived analytically within this respect we develop an exact riemann solver to present the complete solution structure a necessary and sufficient condition for the existence of solution to the riemann problem is derived and presented in terms of initial data furthermore we present a necessary and sufficient condition on initial data which provides the information about the existence of a rarefaction wave or a shock wave for one or three family of waves to validate the performance and the efficiency of the developed exact riemann solver a series of test problems selected from the open literature are presented and compared with independent numerical methods simulation results demonstrate that the present exact solver is capable of reproducing the complete wave propagation using the current drift flux equations as the numerical resolution the provided computations indicate that accurate results be accomplished efficiently and in a satisfactory agreement with the exact solution

toward a mathematical analysis for drift flux multiphase flow models in networks dynamics of multiphase flows through networks are considered the dynamics of flow through the connected arcs are governed by an isothermal no slip drift flux model such problems arise in the context of multicomponent flows or in gas transport in pipe networks in which a phase change takes place due to geometrical or physical forces coupling conditions for the vertices joints in a network have been proposed we present conditions at and introduce a mathematical representation of the vertex flow for the no slip drift flux case of multiphase flows mathematical analysis of coupling conditions at the vertices as well as numerical simulations and comparative studies with theoretical predictions are undertaken

estimation of integrated transition hazards and stage occupation probabilities for non markov systems under dependent censoring we propose nonparametric estimators of the stage occupation probabilities and transition hazards for a multistage system that is not necessarily markovian using data that are subject to dependent right censoring we assume that the hazard of being censored at a given instant depends on a possibly time dependent covariate process as opposed to assuming a fixed censoring hazard independent censoring the estimator of the integrated transition hazard matrix has a nelson aalen form where each of the counting processes counting the number of transitions between states and the risk sets for leaving each stage have an ipcw inverse probability of censoring weighted form we estimate these weights using aalen s linear hazard model finally the stage occupation probabilities are obtained from the estimated integrated transition hazard matrix via product integration consistency of these estimators under the general paradigm of non markov models is established and asymptotic variance formulas are provided simulation results show satisfactory performance of these estimators an analysis of data on graft versus host disease for bone marrow transplant patients is used as an illustration

semi nonparametric maximum likelihood estimation on developpe une approche basee sur une innovation due a phillips 1983 sur les approximations des fonctions de densite

estimating tumor incidence rates in animal carcinogenicity experiments tumor incidence is the primary measure of carcinogenesis this article focuses on estimating time dependent incidence rates in animal experiments with few sacrifices when the context of observation is known for none or all of the animals dying with the tumor of interest previous results are obtained under relaxed assumptions the link with existing semiparametric and nonparametric procedures based on latent failure times is exploited by using these methods to compute maximum likelihood estimates of the incidence rates without introducing latent random variables nonparametric estimators that are appropriate when all contexts of observation are known are generalized to the case in which the contexts of observation are unknown for a subset of the tumor bearing animals