Discussion of “Virtual age,is it real?”

In this note, some point of views on virtual ages are presented in terms of the discussion paper written by Finkelstein and Cha, which include generalized stochastic order‐based virtual ages, system‐level virtual ages, virtual ages in Weibull distribution and repair degrees with virtual ages. Finally, some possible future researches on virtual ages are described.     

Instability and violence in Imperial Rome: A “laboratory” for studying social contagion?

Imperial Rome with its >50% assassination rate of emperors, many of whom are depicted in history as ‘deranged’, initially appears a chaotic period of history beyond the purview of science. But time series analysis indicates this violence occurred non‐randomly: reign length was autocorrelated and demonstrated ‘memory persistence,’ and short reigns occurred in clusters. Additionally, deviations from average reign‐length occurred in patterns matching the Empire's rise and decline. A model is proposed for how army‐backed usurpation and post‐coup instability likely generated the observed cycles. The five‐century span of Imperial Rome likely makes it the longest‐lived regime with fair documentation, and potentially provides a ‘laboratory’ with ongoing relevance for studying transmission of violence and instability. © 2016 Wiley Periodicals, Inc. Complexity 21: 613–622, 2016     

“Do we teach subjects or students?” Analyzing science and mathematics teacher conversations about issues of equity in the classroom

Teachers involved in a Master's level course in diversity participated in virtual, synchronous, anonymized discussions around issues of ethnic and racial diversity, gender, and stereotypes that could impact their students’ participation in fields related to science, technology, engineering, and mathematics (STEM). Guided by theoretical frameworks from Social Cognitive Career Theory (SCCT) and Critical Race Theory (CRT), a convenience sample of 14 science and mathematics teachers participated in a series of virtual chats using open‐ended questioning and facilitated by two university instructors. Using conversation and critical discourse analyses, three primary themes emerged: understanding of issues related to stereotypes, encouragement of females and minorities to pursue careers in STEM, and the place for diversity discussions in science and mathematics classrooms. The teachers felt burdened by curricular and administrative constraints that inhibit their ability to participate in thought‐provoking critical conversations. The paper concludes with a discussion of ways teachers can assist in the STEM career identity development of their underrepresented females and students of color and calls for research that combines the key findings in SCCT and CRT to build confidence and capacity for teachers to effectively confront issues of racism, sexism, and stereotyping in science and mathematics classrooms.     

Where Are the Nodes of “Good” Interpolation Polynomials on the Real Line?

It is shown that the interval where the nodes of a “good” interpolation polynomial are situated is strongly connected with the Mhaskar–Rahmanov–Saff number.     

What Sense Do Children Make of Three‐Dimensional,Life‐Sized “Representations” of Animals?

One way of investigating what children learn about animals is to examine, the menial models they reveal through their talk when they come face to face with animal representations. In this study, representations were provided by (a) robotic models in a museum, (b) preserved animals in a museum, and (c) preserved animals borrowed from a museum and presented in a school setting. By recording pupil talk in these three settings and then analyzing the content of the talk for comments about the anatomy of animals, their behaviour, habitat features, and so on, both similarities and significant differences are revealed by this study, depending on the setting. Based on these findings, recommendations are made for science education in both classroom and museum settings.     

Exact simulation of the stationary distribution of the FIFO M/G/c queue: the general case for <Emphasis Type="Italic">ρ</Emphasis><<Emphasis Type="Italic">c</Emphasis>

We present an exact simulation algorithm for the stationary distribution of customer delay for FIFO M/G/c queues in which ρ=λ/μ<c. In Sigman (J. Appl. Probab. 48A:209–216, 2011) an exact simulation algorithm was presented but only under the strong condition that ρ<1 (super stable case). We only assume that the service-time distribution G(x)=P(S≤x), x≥0, with mean 0<E(S)=1/μ<∞, and its corresponding equilibrium distribution $G_{e}(x)=\mu\int_{0}^{x} P(S>y)\,dy$G_{e}(x)=\mu\int_{0}^{x} P(S>y)\,dy are such that samples of them can be simulated. Unlike the methods used in Sigman (J. Appl. Probab. 48A:209–216, 2011) involving coupling from the past, here we use different methods involving discrete-time processes and basic regenerative simulation, in which, as regeneration points, we use return visits to state 0 of a corresponding random assignment (RA) model which serves as a sample-path upper bound.     

On the local Artin conductor f<Subscript>Artin</Subscript> (Χ) of a character Χ of Gal(E/K) — II: Main results for the metabelian case

This paper which is a continuation of [2], is essentially expository in nature, although some new results are presented. LetK be a local field with finite residue class fieldK _k. We first define (cf. Definition 2.4) the conductorf(E/K) of an arbitrary finite Galois extensionE/K in the sense of non-abelian local class field theory as wheren _G is the break in the upper ramification filtration ofG = Gal(E/K) defined by . Next, we study the basic properties of the idealf(E/K) inO _k in caseE/K is a metabelian extension utilizing Koch-de Shalit metabelian local class field theory (cf. [8]). After reviewing the Artin charactera _G : G → ℂ ofG := Gal(E/K) and Artin representationsA _g G → G →GL(V) corresponding toa _G : G → ℂ, we prove that (Proposition 3.2 and Corollary 3.5) where Χ_gr : G → ℂ is the character associated to an irreducible representation ρ: G → GL(V) ofG (over ℂ). The first main result (Theorem 1.2) of the paper states that, if in particular,ρ : G → GL(V) is an irreducible representation ofG(over ℂ) with metabelian image, then where Gal(E^ker(ρ)/E^ker(ρ)•) is any maximal abelian normal subgroup of Gal(E^ker(ρ)/K) containing Gal(E^ker(ρ) /K)′, and the break n_G/ker(ρ) in the upper ramification filtration of G/ker(ρ) can be computed and located by metabelian local class field theory. The proof utilizes Basmaji’s theory on the structure of irreducible faithful representations of finite metabelian groups (cf. [1]) and on metabelian local class field theory (cf. [8]). We then discuss the application of Theorem 1.2 on a problem posed by Weil on the construction of a ‘natural’A _G ofG over ℂ (Problem 1.3). More precisely, we prove in Theorem 1.4 that ifE/K is a metabelian extension with Galois group G, then Kazim İlhan ikeda whereN runs over all normal subgroups of G, and for such anN, V _n denotes the collection of all ∼-equivalence classes [ω]∼, where ‘∼’ denotes the equivalence relation on the set of all representations ω : (G/N)^• → ℂ^Χ satisfying the conditions Inert(ω) = {δ ∈ G/N : ℂ_δ} = ω =(G/N) and where δ runs over R((G/N)^•/(G/N)), a fixed given complete system of representatives of (G/N)^•/(G/N), by declaring that ω₁ ∼ ω₂ if and only if ω₁ = ω _2,δ for some δ ∈ R((G/N)^•/(G/N)). Finally, we conclude our paper with certain remarks on Problem 1.1 and Problem 1.3.     

Dispersive estimates for Schrödinger operators in the presence of a resonance and/or an eigenvalue at zero energy in dimension three: II

We investigate boundedness of the evolutione ^itH in the sense ofL ²(ℝ³→L ²(ℝ³) as well asL ¹(ℝ³→L ^∞(ℝ³) for the non-selfadjoint operator where μ>0 andV ₁, V₂ are real-valued decaying potentials. Such operators arise when linearizing a focusing NLS equation around a standing wave, and the aforementioned bounds are needed in the study of nonlinear asymptotic stability of such standing waves. We derive our results under some natural spectral assumptions (corresponding to a ground state soliton of NLS), see A1)–A4) below, but without imposing any restrictions on the edges±μ of the essential spectrum. Our goal is to develop an “axiomatic approach,” which frees the linear theory from any nonlinear context in which it may have arisen. This work was initiated in June of 2004, while the first author visited Caltech, and he wishes to thank that institution for its hospitality and support. The first author was partially supported by the NSF grant DMS-0303413. The second author was partially supported by a Sloan fellowship and the NSF grant DMS-0300081. The authors thank Avy Soffer for his interest in this work.     

Is There Still a Place for Independent Research into Issues of Public Policy in England and Wales in the 1980's? A Case Study from the Field of Health Care: Modelling Hospital Costs

This paper is concerned with the viability of independent research into issues of public policy in a climate which is becoming increasingly hostile. The general argument is illustrated by one specific example relating to the development of models of hospital inpatient costs in the National Health Service. In a recent publication by staff of the Operational Research Service of the Department of Health and Social Security a model (denoted the C-G-N model) of hospital costs is put forward. However, no mention is made of an alternative model (denoted the A-B model) published some two years previously and we have therefore decided to compare the two models in terms of general structure, fit to the available observational data and applicability. It is shown that the C-G-N model was applied by its authors in a form which involves an heteroscedastic residual error term. When this model is fitted to a representative data set, with an appropriate weighting factor which produces homoscedastic errors, substantial differences are found in the corresponding parameter estimates. The C-G-N model in its original and modified versions is then compared with the A-B model, and it is shown that the latter is more parsimonious in terms of parameters, is applicable to a wider range of types of hospital and fits the available empirical data somewhat better than either version of the former. Furthermore, there are substantial differences in the conclusions which might be drawn on the basis of the various models in several important classes of application. An outline is given of a more complex model, denoted the component model, which incorporates features of both the C-G-N and A-B models, provides a better fit to the empirical data than either and has a structure which is more satisfactory for a wide range of applications.     

Positive Solutions of the Equation (t) = −c(t)x(t − τ) in the Critical Case

The equation (t) − c(t)x(t − τ) is considered in the critical case. For it, the asymptotic behavior of dominant and subdominant solutions is studied. A generalization is made and connections with known results are discussed.     

Homogenization of the boundary value problem for the Laplace operator in a domain perforated along (<Emphasis Type="Italic">n</Emphasis> – 1)-dimensional manifold with nonlinear Robin type boundary condition on the boundary of arbitrary shaped holes: Critical case

The asymptotic behavior of the solution to the boundary value problem for the Laplace operator in a domain perforated along an (n ? 1)-dimensional manifold is studied. A nonlinear Robin-type condition is assumed to hold on the boundary of the holes. The basic difference of this work from previous ones concerning this subject is that the domain is perforated not by balls, but rather by sets of arbitrary shape (more precisely, by sets diffeomorphic to the ball). A homogenized model is constructed, and the solutions of the original problem are proved to converge to the solution of the homogenized one.     

Optimality conditions for multiple objective fractional subset programming with ( , ρ,σ,θ )-V-type-I and related non-convex functions

In this paper, we introduce a new class of generalized convex n-set functions, called ( , ρ,σ,θ)-V-Type-I and related non-convex functions, and then establish a number of parametric and semi-parametric sufficient optimality conditions for the primal problem under the aforesaid assumptions. This work partially extends an earlier work of [G.J. Zalmai, Efficiency conditions and duality models for multiobjective fractional subset programming problems with generalized ( , α, ρ, θ)-V-convex functions, Comput. Math. Appl. 43 (2002) 1489–1520] to a wider class of functions.     

σ-core and -core of bounded sequences

In this paper we characterize matrices that map every bounded sequence into one whose σ-core is a subset of the -core of the original sequence.     

Approximation in Lp( ) from Spaces Spanned by the Perturbed Integer Translates of a Radial Function

The problem of approximating smooth L_p-functions from spaces spanned by the integer translates of a radially symmetric function φ is very well understood. In case the points of translation, Ξ, are scattered throughout ^d, the approximation problem is only well understood in the “stationary” setting. In this work, we provide lower bounds on the obtainable approximation orders in the “non-stationary” setting under the assumption that Ξ is a small perturbation of ^d. The functions which we can approximate belong to certain Besov spaces. Our results, which are similar in many respects to the known results for the case Ξ= ^d, apply specifically to the examples of the Gauss kernel and the generalized multiquadric.