bayesian sensitivity analysis for unmeasured confounding in observational studies we consider bayesian sensitivity analysis for unmeasured confounding in observational studies where the association between a binary exposure binary response measured confounders and a single binary unmeasured confounder can be formulated using logistic regression models a model for unmeasured confounding is presented along with a family of prior distributions that model beliefs about a possible unknown unmeasured confounder simulation from the posterior distribution is accomplished using markov chain monte carlo because the model for unmeasured confounding is not identifiable standard large sample theory for bayesian analysis is not applicable consequently the impact of different choices of prior distributions on the coverage probability of credible intervals is unknown using simulations we investigate the coverage probability when averaged with respect to various distributions over the parameter space the results indicate that credible intervals will have approximately nominal coverage probability on average when the prior distribution used for sensitivity analysis approximates the sampling distribution of model parameters in a hypothetical sequence of observational studies we motivate the method in a study of the effectiveness of beta blocker therapy for treatment of heart failure

finite time stabilization of a class of cascade nonlinear switched systems under state dependent switching this paper investigates finite time stabilization fts problem for a class of cascade nonlinear switched systems unlike the existing approach based on time dependent switching strategy in which the switching instants must be given in advance largest region function strategy i e state dependent switching strategy is adopted to design the switching signal based on multiple lyapunov like functions method sufficient conditions for fts of cascade nonlinear switched systems are derived and the corresponding sliding motion problems are also considered finally an example is given to illustrate the applicability and the effectiveness of the proposed method

case control studies assessing the effect of a confounding factor summary upper and lower bounds for the strength of the effect of a dichotomous confounding factor on the exposure disease relationship are developed for case control studies of a a problem in the design and analysis of a case control study is the identification of confounding factors controversies frequently arise about whether an exposure disease relationship is spurious i e caused by extraneous or confounding factors that were not measured or controlled as part of the study the effect of confounding factors has been discussed quantitatively by bross 1966 and schlesselman 1978 in this paper we develop upper and lower bounds for the stratum specific odds ratios which are applicable for assessing the effect of a confounding factor we restrict our attention to the simple case involving a dichotomous disease variable denoted by d if present and d if absent a dichotomous exposure variable denoted by e if present and e if absent and a single dichotomous extraneous factor f with f1 and fo denoting its two levels 2 bounds we parameterize the joint distributions of e and f in d and d as follows

the zero divisor graph of a commutative ring for each commutative ring r we associate a simple graph r we investigate the interplay between the ring theoretic properties of r and the graph theoretic properties of r

sensitivity analysis for certain permutation inferences in matched observational studies summary in observational studies treatments are not randomly assigned to experimental units so that randomization tests and their associated interval estimates are not generally applicable in an effort to compensate for the lack of randomization treated and control units are often matched on the basis of observed covariates however the possibility remains of bias due to residual imbalances in unobserved covariates a general though simple method is proposed for displaying the sensitivity of permutation inferences to a range of assumptions about unobserved covariates in matched observational studies the sensitivity analysis is applicable to wilcoxon s signed rank test to the mcnemar cox test for paired binary responses and to some matching problems with a variable number of controls

planar zero divisor graphs abstract this paper answers the question of anderson frazier lauve and livingston for which finite commutative rings r is the zero divisor graph r planar we build upon and extend work of akbari maimani and yassemi who proved that if r is any local ring with more than 32 elements and r is not a field then r is not planar they left open the question is it true that for any local ring r of cardinality 32 which is not a field r is not planar in this paper we answer this question in the affirmative we prove that if r is any local ring with more than 27 elements and r is not a field then r is not planar moreover we determine all finite commutative local rings whose zero divisor graph is planar

beck s coloring of a commutative ring a commutative ring r can be considered as a simple graph whose vertices are the elements of r and two different elements x and y of r are adjacent if and only if xy 0 beck conjectured that r cl r we give a counterexample where r is a finite local ring with cl r 5 but r 6 we show that if a is a regular noetherian ring with maximal ideals n1 ns such that each a ni is finite then for r a nn11 nnss r cl r finally we give a complete listing of all finite rings r with r 4

sensitivity analysis for m estimates tests and confidence intervals in matched observational studies huber s m estimates use an estimating equation in which observations are permitted a controlled level of influence the family of m estimates includes least squares and maximum likelihood but typical applications give extreme observations limited weight maritz proposed methods of exact and approximate permutation inference for m tests confidence intervals and estimators which can be derived from random assignment of paired subjects to treatment or control in contrast in observational studies where treatments are not randomly assigned subjects matched for observed covariates may differ in terms of unobserved covariates so differing outcomes may not be treatment effects in observational studies a method of sensitivity analysis is developed for m tests m intervals and m estimates it shows the extent to which inferences would be altered by biases of various magnitudes due to nonrandom treatment assignment the method is developed for both matched pairs with one treated subject matched to one control and for matched sets with one treated subject matched to one or more controls the method is illustrated using two studies i a paired study of damage to dna from exposure to chromium and nickel and ii a study with one or two matched controls comparing side effects of two drug regimes to treat tuberculosis the approach yields sensitivity analyses for i m tests with huber s weight function and other robust weight functions ii the permutational t test which uses the observations directly and iii various other procedures such as the sign test noether s test and the permutation distribution of the efficient score test for a location family of distributions permutation inference with covariance adjustment is briefly discussed

coloring of commutative rings the purpose of this article is to present the idea of coloring of a commutative ring this idea establishes a connection between graph theory and commutative ring theory which hopefully will turn out to be mutually beneficial for these two branches of mathemathics in this introductory paper we shall mainly be interested in characterizing and discussing the rings which are finitely colorable leaving aside for the moment possible applications to graph theory let r be a commutative ring we consider r as a simple graph whose vertices are the elements of r such that two different elements x and y are adjacent iff xy 0 we let x r denote the chromatic number of the graph i e the minimal number of colors which can be assigned to the elements of r in such a way that every two adjacent elements have different colors a subset c xi x is called a clique provided xixj 0 for all i j if r contains a clique with n elements and every clique has at most y1 elements we say that the clique number of r is n and write clique r n if the sizes of the cliques in r are not bounded we define clique r co we shall show that clique r co actually entails the existence of an infinite clique obviously x r 3 clique r and for general graph g we certainly may have x g clique g however in the case of commutative rings we have not found any example where x r clique r the lack of such counterexamples together with the fact that we have been able to establish the equality x r clique r for certain rather wide classes of rings like reduced and principal ideal rings motivates the following conjecture

assessing the sensitivity of regression results to unmeasured confounders in observational studies this paper presents a general approach for assessing the sensitivity of the point and interval estimates of the primary exposure effect in an observational study to the residual confounding effects of unmeasured variable after adjusting for measured covariates the proposed method assumes that the true exposure effect can be represented in a regression model that includes the exposure indicator as well as the measured and unmeasured confounders one can use the corresponding reduced model that omits the unmeasured confounder to make statistical inferences about the true exposure effect by specifying the distributions of the unmeasured confounder in the exposed and unexposed groups along with the effects of the unmeasured confounder on the outcome variable under certain conditions there exists a simple algebraic relationship between the true exposure effect in the full model and the apparent exposure effect in the reduced model one can then estimate the true exposure effect by making a simple adjustment to the point and interval estimates of the apparent exposure effect obtained from standard software or published reports the proposed method handles both binary response and censored survival time data accommodates any study design and allows the unmeasured confounder to be discrete or normally distributed we describe applications on two major medical studies

output feedback control of markovian jump repeated scalar nonlinear systems this paper is concerned with the induced l2 dynamic output feedback controller dofc design problem for discrete time markovian jump repeated scalar nonlinear systems by employing both the switching sequence dependent lyapunov function approach and the positive definite diagonally dominant lyapunov function technique a sufficient condition is first established which guarantees the underlying system to be stochastically stable with an induced l2 disturbance attenuation performance then the desired full or reduced order dofcs are designed by using projection approach cone complementarity linearization procedure is employed to cast the nonconvex feasibility problem into a sequential minimization problem finally a numerical example is presented to show the effectiveness of the proposed methods

using mixed integer programming for matching in an observational study of kidney failure after surgery this article presents a new method for optimal matching in observational studies based on mixed integer programming unlike widely used matching methods based on network algorithms which attempt to achieve covariate balance by minimizing the total sum of distances between treated units and matched controls this new method achieves covariate balance directly either by minimizing both the total sum of distances and a weighted sum of specific measures of covariate imbalance or by minimizing the total sum of distances while constraining the measures of imbalance to be less than or equal to certain tolerances the inclusion of these extra terms in the objective function or the use of these additional constraints explicitly optimizes or constrains the criteria that will be used to evaluate the quality of the match for example the method minimizes or constrains differences in univariate moments such as means variances and skewness differences in multivariate moments such as correlations between covari

almost sure stability of markov jump linear systems with deterministic switching the technical note studies a class of linear systems whose piecewise constant dynamic matrix is subject to both stochastic jumps governed by a markov chain and deterministic switches these systems will be dubbed switching dynamics markov jump linear systems sd mjls sufficient conditions for exponential almost sure stability eas stability are established under either hard or average constraints on the dwell time between switching instants the proof relies on easy to check norm contractivity conditions and the ergodic law of large numbers

some properties of comaximal right ideal graph of a ring abstract for a ring r not necessarily commutative with identity the comaximal right ideal graph of r denoted by g r is a graph whose vertices are the nonzero proper right ideals of r and two distinct vertices i and j are adjacent if and only if i j r in this paper we consider a subgraph g r of g r induced by v g r j r where j r is the set of all proper right ideals contained in the jacobson radical of r we prove that if r contains a nontrivial central idempotent then g r is a star graph if and only if r is isomorphic to the direct product of two local rings and one of these two rings has unique maximal right ideal 0 in addition we also show that r has at least two maximal right ideals if and only if g r is connected and its diameter is at most 3 then completely characterize the diameter of this graph

comaximal graph of commutative rings abstract let r be a commutative ring with identity let r be a graph with vertices as elements of r where two distinct vertices a and b are adjacent if and only if r a r b r in this paper we consider a subgraph 2 r of r which consists of non unit elements we look at the connectedness and the diameter of this graph we completely characterize the diameter of the graph 2 r j r in addition it is shown that for two finite semi local rings r and s if r is reduced then r s if and only if r s

strong control of the familywise error rate in observational studies that discover effect modification by exploratory methods an effect modifier is a pretreatment covariate that affects the magnitude of the treatment effect or its stability when there is effect modification an overall test that ignores an effect modifier may be more sensitive to unmeasured bias than a test that combines results from subgroups defined by the effect modifier if there is effect modification one would like to identify specific subgroups for which there is evidence of effect that is insensitive to small or moderate biases in this paper we propose an exploratory method for discovering effect modification and combine it with a confirmatory method of simultaneous inference that strongly controls the familywise error rate in a sensitivity analysis despite the fact that the groups being compared are defined empirically a new form of matching strength k matching permits a search through more than k covariates for effect modifiers in such a way that no pairs are lost provided that at most k covariates are selected to group the pairs in a strength k match each set of k covariates is exactly balanced although a set of more than k covariates may exhibit imbalance we apply the proposed method to study the effects of the earthquake that struck chile in 2010

necessary and sufficient conditions for analysis and synthesis of markov jump linear systems with incomplete transition descriptions this technical note is concerned with exploring a new approach for the analysis and synthesis for markov jump linear systems with incomplete transition descriptions in the study not all the elements of the transition rate matrices trms in continuous time domain or transition probability matrices tpms in discrete time domain are assumed to be known by fully considering the properties of the trms and tpms and the convexity of the uncertain domains necessary and sufficient criteria of stability and stabilization are obtained in both continuous and discrete time numerical examples are used to illustrate the results

zero divisor graphs of non commutative rings abstract in a manner analogous to the commutative case the zero divisor graph of a non commutative ring r can be defined as the directed graph r that its vertices are all non zero zero divisors of r in which for any two distinct vertices x and y x y is an edge if and only if x y 0 we investigate the interplay between the ring theoretic properties of r and the graph theoretic properties of r in this paper it is shown that with finitely many exceptions if r is a ring and s is a finite semisimple ring which is not a field and r s then r s for any finite field f and each integer n 2 we prove that if r is a ring and r m n f then r m n f redmond defined the simple undirected graph r obtaining by deleting all directions on the edges in r we classify all ring r whose r is a complete graph a bipartite graph or a tree

generalized cayley graphs associated to commutative rings abstract let r be a commutative ring with identity element for a natural number n we associate a simple graph denoted by r n with r n 0 as the vertex set and two distinct vertices x and y in r n being adjacent if and only if there exists an n n lower triangular matrix a over r whose entries on the main diagonal are non zero and such that ax t y t or ay t x t where for a matrix b b t is the matrix transpose of b when we consider the ring r as a semigroup with respect to multiplication then r 1 is the usual undirected cayley graph over a semigroup hence r n is a generalization of cayley graph in this paper we study some basic properties of r n we also determine all isomorphic classes of finite commutative rings whose generalized cayley graph has genus at most three

finite time stability and stabilization for ito type stochastic markovian jump systems with generally uncertain transition rates abstract this paper investigates the problems of finite time stability and stabilization for stochastic markovian jump systems with generally uncertain transition rates smjswgutrs firstly a less conservative stability criterion is presented by a mode dependent approach then the state feedback controller and observer based controller are designed by a cone complementary linearization method and two specific algorithms are presented finally an example is used to illustrate our results

technical communique finite time control of linear systems subject to parametric uncertainties and disturbances in this paper we consider finite time control problems for linear systems subject to time varying parametric uncertainties and to exogenous constant disturbances the main result provided is a sufficient condition for robust finite time stabilization via state feedback it can be applied to problems with both non zero initial conditions and unknown constant disturbances this condition is then reduced to a feasibility problem involving linear matrix inequalities lmis a detailed example is presented to illustrate the proposed methodology

state estimation and sliding mode control of markovian jump singular systems this paper is concerned with the state estimation and sliding mode control problems for continuous time markovian jump singular systems with unmeasured states firstly a new necessary and sufficient condition is proposed in terms of strict linear matrix inequality lmi which guarantees the stochastic admissibility of the unforced markovian jump singular system then the sliding mode control problem is considered by designing an integral sliding surface function an observer is designed to estimate the system states and a sliding mode control scheme is synthesized for the reaching motion based on the state estimates it is shown that the sliding mode in the estimation space can be attained in a finite time some conditions for the stochastic admissibility of the overall closed loop system are derived finally a numerical example is provided to illustrate the effectiveness of the proposed theory

stability for delayed switched systems with markov jump parameters and generally incomplete transition rates abstract exponential mean square stability for delayed switched systems with markov jump parameters and generally incomplete transition rates is discussed the switching dynamics among the operation modes are considered to be governed by a high level with average dwell time switching adts and a low level with stochastic markov switching many practical systems such as general economic model subject to unpredictable structural changes can be described by switching markov jump systems smjss with generally incomplete transition rates by resorting to average dwell time switching approach sufficient conditions are proposed to ensure the underlying system exponentially mean square stable finally the theoretical results are applied to a general economic model to demonstrate the effectiveness applicability and superiority of the main results

impact of multiple matched controls on design sensitivity in observational studies summary in an observational study one treated subject may be matched for observed covariates to either one or several untreated controls the common motivation for using several controls rather than one is to increase the power of a test of no effect under the doubtful assumption that matching for observed covariates suffices to remove bias from nonrandom treatment assignment does the choice between one or several matched controls affect the sensitivity of conclusions to violations of this doubtful assumption with continuous responses it is known that reducing the heterogeneity of matched pair differences reduces sensitivity to unmeasured biases but increasing the sample size has a highly circumscribed effect on sensitivity to bias is the use of several controls rather than one analogous to a reduction in heterogeneity or to an increase in sample size the issue is examined for huber s m statistics including the t test the examination having three components an example asymptotic calculations using design sensitivity and a simulation use of multiple controls with continuous responses yields a nontrivial reduction in sensitivity to unmeasured biases an example looks at lead and cadmium in the blood of smokers from the 2008 national health and nutrition examination survey a by product of the discussion is a new result giving the design sensitivity for the permutation distribution of m statistics

rings of order p5 part i nonlocal rings abstract in this paper and its sequel the structure and classification up to isomorphism of all finite rings of order p 5 are determined the theory of semiperfect rings is here applied to deal with the nonlocal rings of this order in part ii we shall treat the local rings

finite time stability and stabilization of ito stochastic systems with markovian switching mode dependent parameter approach this technical note is concerned about the finite time stability and stabilization for ito stochastic systems with markovian switching a mode dependent parameter approach is proposed to give a sufficient condition for finite time stability and its superiority to common parameter approach is analyzed moreover the finite time stabilization is studied and two new sufficient conditions for the existence of state and output feedback controllers are presented in terms of coupled matrix inequalities a n mode algorithm is given for solving the obtained matrix inequalities arising from finite time stability stabilization finally an example is employed to illustrate the effectiveness of our obtained results

linear network coding over rings part i scalar codes and commutative alphabets linear network coding over finite fields is a well studied problem we consider the more general setting of linear coding for directed acyclic networks with finite commutative ring alphabets our results imply that for scalar linear network coding over commutative rings fields can always be used when the alphabet size is flexible but other rings may be needed when the alphabet size is fixed we prove that if a network has a scalar linear solution over some finite commutative ring then the unique smallest such commutative ring is a field we also show that fixed size commutative rings are quasi ordered such that all the scalar linearly solvable networks over any given ring are also scalar linearly solvable over any higher ordered ring we study commutative rings that are maximal with respect to this quasi order as they may be considered the best commutative rings of a given size we prove that a commutative ring is maximal if and only if some network is scalar linearly solvable over the ring but not over any other commutative ring of the same size furthermore we show that maximal commutative rings are direct products of certain fields specified by the integer partitions of the prime factor multiplicities of the ring s size finally we prove that there is a unique maximal commutative ring of size m if and only if each prime factor of m has multiplicity in 1 2 3 4 6 as consequences 1 every finite field is such a maximal ring and 2 for each prime p some network is scalar linearly solvable over a commutative ring of size p k but not over the field of the same size if and only if k not in 1 2 3 4 6

when a zero divisor graph is planar or a complete r partite graph abstract let r be the zero divisor graph of a commutative ring r an interesting question was proposed by anderson frazier lauve and livingston for which finite commutative rings r is r planar we give an answer to this question more precisely we prove that if r is a local ring with at least 33 elements and r then r is not planar we use the set of the associated primes to find the minimal length of a cycle in r also we determine the rings whose zero divisor graphs are complete r partite graphs and show that for any ring r and prime number p p 3 if r is a finite complete p partite graph then z r p 2 r p 3 and r is isomorphic to exactly one of the rings z p 3 z p x y xy y 2 x z p 2 y py y 2 ps where 1 s p

finite time stabilization for a class of switched time delay systems under asynchronous switching switched control systems can be used to describe many practical processes with switching phenomena such as power electronics mechanical systems etc in this paper the problem of finite time stabilization under asynchronous switching is dealt with for a class of switched time delay systems with nonlinear disturbances firstly the nonlinear uncertainties are transformed into the linear time varying forms via the differential mean value theorem under some assumptions secondly by applying the average dwell time method and convexity principle a finite time stability condition for the unforced switched time delay system is established finally an asynchronous switching state feedback controller is designed which renders the considered system finite time stable a numerical example is provided to show the effectiveness of the developed results

stabilization of singular markovian jump systems with generally uncertain transition rates this note is devoted to investigating the stability and stabilization problems for continuous time singular markovian jump systems smjss with generally uncertain transition rates gutrs in this gutr singular model each transition rate can be completely unknown or only its estimate value is known in terms of a set of coupled linear matrix inequalities lmis a sufficient condition is established to ensure the systems to be regular impulse free and stochastically stable moreover the corresponding sufficient condition on the existence of a mode dependent state feedback controller is derived to guarantee the closed loop systems stochastically admissible by applying the lmi technique finally a numerical example is presented to illustrate the effectiveness and efficiency of the proposed method

co maximal graph of non commutative rings let r be a ring not necessarily commutative with 1 following sharma and bhatwadekar p k sharma s m bhatwadekar a note on graphical representation of rings j algebra 176 1995 124 127 we define a graph on r r with vertices as elements of non units of r where two distinct vertices a and b are adjacent if and only if ra rb r in this paper we investigate the behavior of r we are able to prove that if r is left artinian then r j r is connected and if r j r is a forest then r j r is a star graph where j r is the jacobson radical of r for any finite field fq we obtain the minimal degree the maximal degree the connectivity the clique number and the chromatic number of mn fq finally for any finite field and any integer n 2 we prove that if r is a ring with identity and r mn f then r mn f we also prove that if r and s are two finite commutative rings with identity and n m 2 such that mn r mm s then n m and r s provided that r is reduced

linear network coding over rings part ii vector codes and non commutative alphabets in part i we studied linear network coding over finite commutative rings and made comparisons to the well studied case of linear network coding over finite fields here we consider the more general setting of linear network coding over finite possibly non commutative rings and modules we prove the following results regarding the linear solvability of directed acyclic networks over various finite alphabets for any network the following are equivalent i vector linear solvability over some field ii scalar linear solvability over some ring and iii linear solvability over some module analogously the following are equivalent a scalar linear solvability over some field b scalar linear solvability over some commutative ring and c linear solvability over some module whose ring is commutative whenever any network is linearly solvable over a module a smallest such module arises in a vector linear solution for that network over a field if a network is scalar linearly solvable over some non commutative ring but not over any commutative ring then such a non commutative ring must have size at least 16 and for some networks this bound is achieved an infinite family of networks is demonstrated each of which is scalar linearly solvable over some non commutative ring but not over any commutative ring whenever p is prime and 1 le k le 6 if a network is scalar linearly solvable over some ring of size p k then it is also k dimensional vector linearly solvable over the field mathrm gf p but the converse does not necessarily hold this result is extended to all k ge 1 when the ring is commutative

a note on graphical representation of rings let r be a commutative ring with identity let g be a graph with vertices as elements of r where two distinct vertices x and y are adjacent if and only if rx ry r in this paper we show that a commutative ring r is a finite ring if and only if the graph g associated with r as above is finitely colourable moreover we show that in this case the chromatic number of the graph g is the sum of the number of maximal ideals and the number of units of r

finite time boundary control for delay reaction diffusion systems abstract this paper considers finite time stabilization and h performance for delay reaction diffusion systems by boundary control first a full domain controller is designed and sufficient conditions are obtained to achieve finite time stability using finite time stability lemma and wirtinger s inequality method then a boundary controller furnished with sufficient conditions to achieve finite time stability is presented when taking into consideration external noise on a delay reaction diffusion system finite horizon h boundary control with a criterion that guarantees the h performance of delay reaction diffusion systems is proposed how to handle neumann boundary conditions and mixed boundary conditions are discussed numerical simulations are carried out to verify the effectiveness of our theoretical results

rings of order p5 part ii local rings abstract the structure and classification up to isomorphism of all local rings of order p5 are given here this completes the determination of all rings of this order which was begun in the companion to this paper

backward stochastic optimal control with mixed deterministic controller and random controller and its applications in linear quadratic control abstract this paper investigates an optimal control problem driven by backward stochastic differential equation bsde with two controllers one is called deterministic controller and the other one is called random controller necessary and sufficient conditions for the mixed optimal control problem are derived a linear quadratic lq case of the mixed optimal control problem is also studied the mixed optimal controllers are explicitly expressed by the solution of a fully coupled mean field forward backward stochastic differential equation sde one of novel features is that a kind of mean field bsde naturally arises from the research on the mixed optimal control problem finally a product management problem is used to illustrate the theoretical results

zero divisor graphs of genus one abstract in this paper we find all rings of the forms z p 1 1 z p n n and z n x x m that have genus at most one

graphs associated to co maximal ideals of commutative rings abstract let r be a commutative ring r with 1 in p k sharma s m bhatwadekar a note on graphical representation of rings j algebra 176 1995 124 127 sharma and bhatwadekar defined a graph on r r with vertices as elements of r where two distinct vertices a and b are adjacent if and only if a r b r r let 2 r be the subgraph of r induced by non unit elements in this paper we derive several properties of 2 r we are able to characterize those rings r for which 2 r j r is a forest and those rings r for which 2 r j r is eulerian where j r is the jacobson radical of r we are also able to show that 2 r max r where g is the clique number of a graph g and max r is the set of maximal ideals of r moreover we find all finite rings r such that the genus of 2 r resp r is at most one

causal conclusions are most sensitive to unobserved binary covariates there is a rich literature that considers whether an observed relation between treatment and response is due to an unobserved covariate in order to quantify this unmeasured bias an assumption is made about the distribution of this unobserved covariate typically that it is either binary or at least confined to the unit interval in this paper this assumption is relaxed in the context of matched pairs with binary treatment and response one might think that a long tailed unobserved covariate could do more damage remarkably that is not the case the most harm is done by a binary covariate so the case commonly considered in the literature is most conservative this has two practical consequences i it is always safe to assume that an unobserved covariate is binary if one is content to make a conservative statement ii when another assumption seems more appropriate say normal covariate there will be less sensitivity than with a binary covariate this assumption implies that it is possible that a relation between treatment and response that is sensitive to unmeasured bias if the unobserved covariate is dichotomous ceases to be sensitive if the unobserved covariate is normally distributed these ideas are illustrated by three examples it is important to note that the claim in this paper applies to our specific setting of matched pairs with binary treatment and response whether the same conclusion holds in other settings is an open question

robust finite time h control for discrete time singular markovian jump systems with time varying delay and actuator saturation in this paper the problem of robust finite time h control for discrete time singular markovian jump systems with time varying delay and actuator saturation is studied first sufficient conditions that guarantee the systems singular stochastic finite time boundedness are derived via constructing a delay dependent lyapunov krasonskii functional and linear matrix inequalities lmi approaches then the results are extended to singular stochastic finite time h boundedness furthermore with these conditions and convex optimization arithmetic the design method of h controller and conditions that ensure the h disturbance attenuation level are obtained finally some numerical examples are presented to illustrate the validity and efficiency of the proposed methods

sensitivity analysis for instrumental variables regression with overidentifying restrictions instrumental variables regression iv regression is a method for making causal inferences about the effect of a treatment based on an observational study in which there are unmeasured confounding variables the method requires one or more valid instrumental variables ivs a valid iv is a variable that is associated with the treatment is independent of unmeasured confounding variables and has no direct effect on the outcome often there is uncertainty about the validity of the proposed ivs when a researcher proposes more than one iv the validity of these ivs can be tested through the overidentifying restrictions test although the overidentifying restrictions test does provide some information the test has no power versus certain alternatives and can have low power versus many alternatives due to its omnibus nature to fully address uncertainty about the validity of the proposed ivs we argue that a sensitivity analysis is needed a sensitivity analysis examines the impact of plausible amounts of

an adaptive and powerful randomization test reference stap article 1992 005view record in web of science record created on 2006 04 04 modified on 2017 05 12

amplification of sensitivity analysis in matched observational studies a sensitivity analysis displays the increase in uncertainty that attends an inference when a key assumption is relaxed in matched observational studies of treatment effects a key assumption in some analyses is that subjects matched for observed covariates are comparable and this assumption is relaxed by positing a relevant covariate that was not observed and not controlled by matching what properties would such an unobserved covariate need to have to materially alter the inference about treatment effects for ease of calculation and reporting it is convenient that the sensitivity analysis be of low dimension perhaps indexed by a scalar sensitivity parameter but for interpretation in specific contexts a higher dimensional analysis may be of greater relevance an amplification of a sensitivity analysis is defined as a map from each point in a low dimensional sensitivity analysis to a set of points perhaps a curve in a higher dimensional sensitivity analysis such that the possible inferences are

finite time stability of a class of non autonomous neural networks with heterogeneous proportional delays in this paper the problem of finite time stability analysis for a class of non autonomous neural networks with heterogeneous proportional delays is considered by introducing a novel constructive approach we derive new explicit conditions in terms of matrix inequalities ensuring that the state trajectories of the system do not exceed a certain threshold over a pre specified finite time interval as a result we also obtain conditions for the power rate global stability of the system numerical examples are given to demonstrate the effectiveness and less restrictiveness of the results obtained in this paper

screening for partial conjunction hypotheses summary we consider the problem of testing for partial conjunction of hypothesis which argues that at least u out of n tested hypotheses are false it offers an in between approach to the testing of the conjunction of null hypotheses against the alternative that at least one is not and the testing of the disjunction of null hypotheses against the alternative that all hypotheses are not null we suggest powerful test statistics for testing such a partial conjunction hypothesis that are valid under dependence between the test statistics as well as under independence we then address the problem of testing many partial conjunction hypotheses simultaneously using the false discovery rate fdr approach we prove that if the fdr controlling procedure in benjamini and hochberg 1995 journal of the royal statistical society series b 57 289 300 is used for this purpose the fdr is controlled under various dependency structures moreover we can screen at all levels simultaneously in order to display the findings on a superimposed map and still control an appropriate fdr measure we apply the method to examples from microarray analysis and functional magnetic resonance imaging fmri two application areas where the need for partial conjunction analysis has been identified

incremental h control for switched nonlinear systems abstract in this paper we investigate the incremental h control for switched nonlinear systems by using a state dependent switching law and an average dwell time approach incorporated with multiple lyapunov functions even if all subsystems are unstable a sufficient condition for the incremental h control problem to be solvable is derived based on the design state dependent switching law furthermore when all subsystems are incrementally globally asymptotically stable igas the switched nonlinear system under the average dwell time scheme is igas and possesses a weighted incremental l2 gain then we extend this result to the case where both igas subsystems and unstable subsystems coexist if the activation time ratio between igas subsystems and unstable ones is not less than a specified constant sufficient conditions for the weighted incremental h performance of the switched system are guaranteed two numerical examples are given to illustrate the validity of the proposed approach

effect modification and design sensitivity in observational studies in an observational study of treatment effects subjects are not randomly assigned to treatment or control so differing outcomes in treated and control groups may reflect a bias from nonrandom assignment rather than a treatment effect after adjusting for measured pretreatment covariates perhaps by matching a sensitivity analysis determines the magnitude of bias from an unmeasured covariate that would need to be present to alter the conclusions of the naive analysis that presumes adjustments eliminated all bias other things being equal larger effects tend to be less sensitive to bias than smaller effects effect modification is an interaction between a treatment and a pretreatment covariate controlled by matching so that the treatment effect is larger at some values of the covariate than at others in the presence of effect modification it is possible that results are less sensitive to bias in subgroups experiencing larger effects two cases are considered i an a priori grouping into a few categ

brief paper robust exponential stabilization for markovian jump systems with mode dependent input delay this paper is concerned with the problem of exponential stabilization for uncertain linear systems with markovian jump parameters and mode dependent input delays sufficient stabilization conditions are developed in terms of matrix inequalities which can be solved by a proposed iterative algorithm based on the cone complementarity linearization ccl method memory controllers are also designed such that the closed loop system is exponentially mean square stable for all admissible uncertainties numerical examples are given to show that the developed method is efficient and less conservative

exponential synchronization of delayed markovian jump complex networks with generally uncertain transition rates this paper investigates the exponential synchronization problem for a class of markovian jump complex networks mjcns with generally uncertain transition rates gutrs in this gutr neural network model each transition rate can be completely unknown or only its estimate value is known this new uncertain model could be applied to many practical cases based on the lyapunov functional method and kronecker product technique a sufficient condition on the exponentially synchronization in mean square is derived in terms of linear matrix inequalities lmis which can be easily solved by using the matlab lmi toolbox finally one numerical example is well studied to illustrate the effectiveness of the developed method