bluuebunny/crossref_metadata_2025 huggingface dataset:
On Limits of Sequences of Algebraic Elements over a Complete Field
Authors: Bhatia Saurabh , Khanduja Sudesh K.
Published: February 2014

Let K be a complete field with respect to a real non-trivial valuation v, and [Formula: see text] be the extension of v to an algebraic closure [Formula: see text] of K. A well-known result of Ostrowski asserts that the limit of a Cauchy sequence of elements of [Formula: see text] does not always belong to [Formula: see text] unless [Formula: see text] is a finite extension of K. In this paper, it is shown that when a Cauchy sequence { bn } of elements of [Formula: see text] is such that the sequence { [K(bn) : K] } of degrees of the extensions K(bn) / K does not tend to infinity as n approaches infinity, then { bn } has a limit in [Formula: see text]. We also give a characterization of those Cauchy sequences { bn } of elements of [Formula: see text] whose limit is not in [Formula: see text], which generalizes a result of Alexandru, Popescu and Zaharescu.
Semistar Invertibility on Integral Domains
Authors: Fontana Marco , Picozza Giampaolo
Published: February 2014

A natural development of the recent work about semistar operations leads to investigate the concept of “semistar invertibility”. Here, we show the existence of a “theoretical obstruction” for extending many results, proved for star-invertibility, to the semistar case. For this reason, we introduce two distinct notions of invertibility in the semistar setting (called ⋆-invertibility and quasi-⋆-invertibility), we discuss the motivations of these “two levels” of invertibility and we extend, accordingly, many classical results proved for the d-, v-, t- and w-invertibility.
Inductive Arguments for the Non-coprime k(GV)-Problem
Authors: Keller Thomas Michael
Published: February 2014

We present some arguments that can be used in an inductive approach to the non-coprime k(GV)-problem.
Classical Quotient Rings and Ordinary Extensions of 2-Primal Rings
Authors: Cho Yong Uk , Kim Nam Kyun , Kwon Mi Hyang , Lee Yang
Published: February 2014

We study classical right quotient rings and ordinary extensions of various kinds of 2-primal rings, constructing examples for situations that raise naturally in the process. We show: (1) Let R be a right Ore ring with P(R) left T-nilpotent. Then Q is a 2-primal local ring with P(Q)=J(Q) = {ab-1 ∈ Q | a ∈ P(R), b ∈ C(0)} if and only if C(0)=C(P(R))=R∖P(R), where Q is the classical right quotient ring of R. (2) Let R be a right Ore ring. Then R[x] is a domain whose classical right quotient ring is a division ring if and only if R is a right p.p. ring with C(P(R))=R∖P(R). As a consequence, if R is a right Noetherian ring, then R[[x]] is a domain whose classical right quotient ring is a division ring if and only if R[x] is a domain whose classical right quotient ring is a division ring if and only if R is a right p.p. ring with C(P(R))=R∖P(R).
On the Derived Series of 3- and 4-Generator Coxeter Groups
Authors: Jeong Kwang-Woo
Published: February 2014

Let G be a group and let φ (G) be the least integer k such that G(k)=G(k+1). If no such k exists, then φ (G)=∞ and we write G ∈ 𝓤. We are interested in the questions which Coxeter groups are in 𝓤 and how large a finite number φ (G) can be for Coxeter groups G. In this paper, we give full answers in the 3- and 4-generator cases.
On Jacobson Near-rings and Special Radicals
Authors: Godloza L. , Groenewald N. J. , Olivier W. A.
Published: February 2014

In this paper, we construct special radicals using class pairs of near-rings. We establish necessary conditions for a class pair to be a special radical class. We then define Jacobson-type near-rings and show that in most cases the class of all near-rings of this type is a special radical class. Subsequently, we investigate the relationship between each Jacobson-type near-ring and the corresponding matrix near-ring.
Fine Representations, Good Roots and R-Groups
Authors: Liang Ke , Zhu Fuhai
Published: February 2014

In this paper, we classify the fine representations and R-groups of quasi-split simple groups, and describe the set of good roots with the help of Yan's method. Part of the results are not new, but the method used here is new and efficient.
Weak Galois and Weak Cocleft Coextensions
Authors: Alonso Álvarez J. N. , Fernández Vilaboa J. M. , González Rodríguez R. , Rodríguez Raposo A. B.
Published: February 2014

For a weak entwining structure (A, C, ψ) living in a braided monoidal category with equalizers and coequalizers, we formulate the notion of weak A-Galois coextension with normal basis and we show that these Galois coextensions are equivalent to the weak A-cocleft coextensions introduced by the authors.
Regular Semigroups Which Are Amalgamation Bases for Finite Semigroups
Authors: Shoji Kunitaka
Published: February 2014

In this paper, we prove that a completely 0-simple (or completely simple) semigroup is an amalgamation base for finite semigroups if and only if it is an amalgamation base for semigroups. By adopting the same method as used in a previous paper, we prove that a finite regular semigroup is an amalgamation base for finite semigroups if its [Formula: see text]-classes are linearly ordered and all of its principal factor semigroups are amalgamation bases for finite semigroups. Finally, we give an example of a finite semigroup U which is an amalgamation base for semigroups, but not all of its principal factor semigroups are amalgamation bases either for semigroups or for finite semigroups.
Strong Semilattices of Implicative Semigroups
Authors: Lee Shuk Yee , Shum K. P. , Wu Congxin
Published: February 2014

It is well known that a strong semilattice of semigroups is still a semigroup. However, it is not known whether the analogous result carries or not for a strong semilattice of implicative semigroups. The main difficulty is that the implicative operation ∗ is hard to define on the semilattice, especially we need the operation ∗ of the implicative semigroup to be compatible with the negatively ordered relation and the semigroup multiplication on the semilattice of implicative semigroups. In this paper, we provide a practical method of constructing such a strong semilattice of mplicative semigroups. Our method is particularly useful in constructing implicative semigroups of large size. A constructed example is given.
Characterizations of Disconnected Matroids
Authors: Mao Hua
Published: February 2014

Three necessary and sufficient conditions for a matroid in the sense of Betten and Wenzel to be disconnected are given in this paper.
Strongly Simple-Injective Rings and Modules
Authors: Amin Ismail , Fathi Yasser , Yousif Mohamed
Published: February 2014

If M and N are right R-modules, M is called simple-N-injective if every R-homomorphism γ from a submodule K of N into M with γ(K) simple extends to N. In this paper, a right R-module M is called strongly simple-injective if M is simple-N-injective for every right R-module N. We investigate the notion of strong simple-injectivity and, as an application, we provide a negative answer to a couple of questions on the subject, and a partial positive answer to another.
The Tits Alternative for Spherical Generalized Tetrahedron Groups
Authors: Fine Benjamin , Hulpke Alexander , große Rebel Volkmar , Rosenberger Gerhard
Published: February 2014

A generalized tetrahedron group is defined to be a group admitting a presentation [Formula: see text] where l, m, n, p, q, r≥ 2, each Wi(a,b) is a cyclically reduced word involving both a and b. These groups appear in many contexts, not least as fundamental groups of certain hyperbolic orbifolds or as subgroups of generalized triangle groups. In this paper, we build on previous work to show that the Tits alternative holds for a generalized tetrahedron group G whenever (p,q,r)≠ (2,2,2), that is, G contains a non-abelian free subgroup or is solvable-by-finite. The term Tits alternative comes from the respective property for finitely generated linear groups over a field (see [16]).
On Divisors of Pseudovarieties Generated by Some Classes of Full Transformation Semigroups
Authors: Fernandes Vítor H.
Published: February 2014

In this paper we present a division theorem for the pseudovariety of semigroups 𝖮𝖣 (𝖮𝖱) generated by all semigroups of order-preserving or order-reversing (orientation-preserving or orientation-reversing) full transformations on a finite chain.
Normal Congruence Subgroups of Hecke Groups
Authors: Chen Bo , Yuan Pingzhi
Published: February 2014

Hecke groups are an important class of discrete subgroups of PSL(2, ℝ), which play an important role in the study of Dirichlet series. Subgroups with finite index of a Hecke group, which are called congruence subgroups, are often used. Let q be a positive integer with [Formula: see text]. For the Hecke group [Formula: see text], the structures of principal congruence subgroups and normal congruence subgroups of level m are investigated in many papers, where m is a prime or a power of an odd prime. In this paper, we deal with the case that the level m is a power of 2.
On Lie Superalgebras of Algebraic Supergroups
Authors: Shu Bin , Zheng Lisun
Published: February 2014

Let G be an algebraic supergroup over a field k, whose pure-even group scheme G ev is a reduced algebraic group scheme, i.e., [Formula: see text] is reduced. In this paper, we prove that Lie (G) can be identified with the Lie superalgebra of admissible left-invariant derivations of k[G].
On Constructing Ideals of the Hall Algebra of Type B
Authors: Liu Qunhua
Published: February 2014

Let Hv(An) and Hv(Bn) be the Hall algebras over ℚ(v) of the Dynkin quivers An and Bn (n ≥ 1), respectively, where v is an indeterminate and the quivers have linear orientation. By comparing the quantum Serre relations, we find a natural algebra epimorphism π : Hv(Bn) → Hv2(An). We determine the kernel of π by giving two sets of generators. Let φ be the natural algebra homomorphism from Hv(An) to the quantized Schur algebra Sv(n + 1, r)(r ≥ 1) and write [Formula: see text] for the induced map. We obtain several ideals of Hv(Bn) by lifting the kernel of φ to the kernel of the composition map [Formula: see text].
On Self-complementary Circulants of Square Free Order
Authors: Sun Shaohui , Xu Jing
Published: February 2014

In this paper, we study the self-complementary Cayley graphs and count the number of isomorphic classes of undirected self-complementary circulants of order n, where n is square free.
Filtrations in Modular Representations of Reductive Lie Algebras
Authors: Li Yiyang , Shu Bin
Published: February 2014

Let G be a connected reductive algebraic group over an algebraically closed field k of prime characteristic p, and 𝔤 = Lie (G). In this paper, we study representations of the reductive Lie algebra 𝔤 with p-character χ of standard Levi form associated with an index subset I of simple roots. With aid of the support variety theory, we prove that a Uχ(𝔤)-module is projective if and only if it is a strong "tilting" module, i.e., admitting both [Formula: see text]- and [Formula: see text]-filtrations. Then by an analogy of the arguments in [2] for G1T-modules, we construct so-called Andersen–Kaneda filtrations associated with each projective 𝔤-module of p-character χ, and finally obtain sum formulas from those filtrations.
Quasi Qn-Filiform Lie Algebras
Authors: Ren Bin , Zhu Linsheng
Published: February 2014

In this paper, we explicitly determine the derivation algebra, automorphism group of quasi Qn-filiform Lie algebras, and by applying some properties of the root space decomposition, we obtain their isomorphism theorem.
A Note on Gorenstein Flat Dimension
Authors: Bennis Driss
Published: February 2014

Unlike the Gorenstein projective and injective dimensions, the majority of results on the Gorenstein flat dimension have been established only over Noetherian (or coherent) rings. Naturally, one would like to generalize these results to any associative ring. In this direction, we show that the Gorenstein flat dimension is a refinement of the classical flat dimension over any ring; and we investigate the relations between the Gorenstein projective dimension and the Gorenstein flat dimension.
Extension Data and Their Lie Algebras
Authors: Khalili Valiollah
Published: February 2014

We state the notion of an extension datum of a root system. This concept generalizes the root system extended by an abelian group. We classify them, and show that there is a one-to-one correspondence between (reduced) root systems extended by an abelian group and (reduced) tame irreducible extension data. We also show that an extension datum, modulo some isotropic roots, is the union of a finite number of tame irreducible extension data.
Jordan Derivations on Strictly Triangular Matrix Rings
Authors: Kuzucuoglu Feride
Published: February 2014

For a lower nil-triangular matrix ring R=NT(n,K), we characterize its Jordan derivations.
On the Structure of the Tensor Square of the Natural Module of the Symmetric Group
Authors: Müller Jürgen , Orlob Johannes
Published: February 2014

We determine the submodule structure of the tensor square of the natural module of the symmetric group over a field of prime characteristic. We also determine the submodule structure of certain Young modules over a field of characteristic 2.
Local Cohomology and Sequentially Cohen-Macaulay Modules
Authors: Mafi Amir
Published: February 2014

Let (R, 𝔪) be a commutative Noetherian local ring and N a finitely generated R-module with dim M =d. It is shown that M is a sequentially Cohen-Macaulay module if and only if the modules [Formula: see text] are either 0 or co-Cohen-Macaulay of Noetherian dimension i for all 0 ≤ i ≤ d.
On n-Isoclinic Pairs of Groups
Authors: Heidarian Shahram , Gholami Ahmad
Published: February 2014

In this paper, we extend the notion of n-isoclinism to the class of all pairs of groups (G,M), where M is a normal subgroup of a group G. The details of that notion are studied and some equivalent conditions are given for two pairs of groups to be n-isoclinic. In addition, the concept of subgroup- and quotient-irreducibility for a pair of groups is defined and we derive how to see whether (G,M) has a pair of subgroups or a pair of factor groups n-isoclinic with (G,M).
Demazure Crystals and Extended Young Diagrams
Authors: Beier Julie C. , Misra Kailash C.
Published: February 2014

For a suitable sequence of Weyl group elements {w(l)}l≥0 we give explicit combinatorial descriptions of the crystals Bw(l)(kΛ0) for the Demazure modules Vw(l)(kΛ0) of the quantum affine Lie algebra [Formula: see text] in terms of extended Young diagrams.
On Almost Prüfer v-Multiplication Domains
Authors: Li Qing
Published: February 2014

Let R be an integral domain and R′ the integral closure of R. In this paper, we introduce the notion of an almost Prüfer v-multiplication domain (APVMD) and continue the investigation of almost GCD-domains (AGCD-domains). We show that R is an APVMD with torsion t-class group if and only if R is an AGCD-domain. Further, we prove that R is an AGCD-domain if and only if R is a UMT-domain with torsion t-class group and R ⊆ R′ is a root extension. Finally, we discuss the polynomial ring over an almost Prüfer v-multiplication domain.
On the π-Quasinormality of 2-Maximal Subgroups of Sylow Subgroups of a Finite Group
Authors: Chen Songliang , Fan Yun
Published: February 2014

Let G be a finite group. A subgroup H of G is called a 2-maximal subgroup of G if there exists a maximal subgroup M of G such that H is a maximal subgroup of M. In this paper, we discuss the influence of π-quasinormality of 2-maximal subgroups of Sylow subgroups on the structure of a finite group, and obtain some sufficient conditions under which the finite group is p-nilpotent, supersolvable, or possesses an ordered Sylow tower.
Lattices Induced by Modular Pull-back Exact Categories
Authors: Li Demei , Xin Lin
Published: February 2014

In this paper, we introduce the notion of a modular pull-back exact category, study modular lattices [Formula: see text] and [Formula: see text] on the skeletally small modular pull-back exact category (𝒞,ℰ) and show that there is an isomorphism between these two lattices. We also study short exact sequences of lattices induced by ℰ-exact sequences.
On Minimal τ-Closed ω-Local Non-ℌ-formations
Authors: Selkin Vadim M.
Published: February 2014

Let Θ be a collection of formations. A formation 𝔉 ∈ Θ is called an ℌΘ-critical formation or a minimal non-ℌ Θ-formation if 𝔉 ⊈ ℌ but the class ℌ of groups contains each proper Θ-subformation of 𝔉. In this paper we study ℌΘ-critical formations, where Θ is the class of all τ-closed ω-local formations.
Abelian Ideals with Given Dimension in Borel Subalgebras
Authors: Luo Li
Published: February 2014

A well-known Peterson's theorem says that the number of abelian ideals in a Borel subalgebra of a rank-r finite-dimensional simple Lie algebra is exactly 2r. In this paper, we determine the dimensional distribution of abelian ideals in a Borel subalgebra of finite-dimensional simple Lie algebras, which is a refinement of Peterson's theorem capturing more Lie algebra invariants.
Quasi-prime Submodules and Developed Zariski Topology
Authors: Abbasi A. , Hassanzadeh-lelekaami D.
Published: February 2014

Let R be a commutative ring with nonzero identity and M be an R-module. Quasi-prime submodules of M and the developed Zariski topology on q Spec (M) are introduced. We also investigate the relationship between algebraic properties of M and topological properties of q Spec (M). Modules whose developed Zariski topology is T0, irreducible or Noetherian are studied, and several characterizations of such modules are given.
On the Hilbert Coefficients and Betti Numbers of the Stanley-Reisner Ring of a Matroid Complex
Authors: Shirmohammadi N.
Published: February 2014

Let S=K[x1,…,xn] be a polynomial ring. Herzog and Zheng conjectured that the i-th Hilbert coefficient of a finitely generated graded Cohen-Macaulay S-module N generated in degree 0 is bounded by the functions of the minimal and maximal shifts in the minimal graded free resolution of N over S and the 0-th Betti number of N. Also, Römer asked whether under the Cohen-Macaulay assumption the i-th Betti number of S/I, where I ⊂ S is a graded ideal, can be bounded by the functions of the minimal and maximal shifts of S/I. In this paper, we provide elementary proofs to establish Herzog and Zheng's conjecture and the upper bound part of Römer's question for the Stanley-Reisner ring of a matroid complex.
Lie Super-bialgebra Structures on Generalized Ramond N=2 Super-Virasoro Algebras
Authors: Yang Hengyun , Yao Tingfu , Yu Yafeng
Published: February 2014

In this paper, Lie super-bialgebra structures on generalized Ramond N=2 super-Virasoro algebras [Formula: see text] are determined. It is proved that all Lie super-bialgebras are coboundary triangular Lie super-bialgebras.
Gröbner-Shirshov Bases for Braid Groups in Adyan-Thurston Generators
Authors: Chen Yuqun , Zhong Chanyan
Published: February 2014

We give a Gröbner-Shirshov basis of the braid group Bn+1 in Adyan-Thurston generators. We also deal with the braid group of type Bn. As results, a new algorithm for getting the Adyan-Thurston normal form is obtained, and a new proof that the braid semigroup [Formula: see text] is a subsemigroup in Bn+1 is given.
A New Characterization of Simple K3-Groups and Some L2(p)
Authors: Zhang Qingliang , Shi Wujie
Published: February 2014

A finite simple group G is called a simple K3-group if |G| has exactly three distinct prime divisors. In this paper, we characterize the finite simple K3-groups and some L2(p) only by using the group order and maximal element order, which generalize some known results.
Pure-injectivity of Tensor Products of Modules
Authors: Pournaki M. R. , Torrecillas B. , Tousi M. , Yassemi S.
Published: February 2014

A classical question of Yoneda asks when the tensor product of two injective modules is injective. A complete answer to this question was given by Enochs and Jenda in 1991. In this paper the analogue question for pure-injective modules is studied.
The Minimal Free Resolution of a Fat Star-Configuration in ℙn
Authors: Ahn Jeaman , Shin Yong Su
Published: February 2014

We find the minimal free resolution of a fat star-configuration 𝕏 in ℙn of type (r,s,t) defined by general forms of degrees d1, …, dr, and show that a fat linear star-configuration 𝕏 in ℙ2 never has generic Hilbert function if (s,t) ≠ (1,1) or (2,2). These two results generalize the interesting results of [2].
Exponential integrators for stiff elastodynamic problems
Authors: Michels Dominik L. , Sobottka Gerrit A. , Weber Andreas G.
Published: February 2014

We investigate the application of exponential integrators to stiff elastodynamic problems governed by second-order differential equations. Classical explicit numerical integration schemes have the shortcoming that the stepsizes are limited by the highest frequency that occurs within the solution spectrum of the governing equations, while implicit methods suffer from an inevitable and mostly uncontrollable artificial viscosity that often leads to a nonphysical behavior. In order to overcome these specific detriments, we devise an appropriate class of exponential integrators that solve the stiff part of the governing equations of motion by employing a closed-form solution. As a consequence, we are able to handle up to three orders of magnitude larger time-steps as with conventional implicit integrators and at the same time achieve a tremendous increase in the overall long-term stability due to a strict energy conservation. The advantageous behavior of our approach is demonstrated on a broad spectrum of complex deformable models like fibers, textiles, and solids, including collision response, friction, and damping.
Interactive generalized penetration depth computation for rigid and articulated models using object norm
Authors: Tang Min , Kim Young J.
Published: February 2014

We present a novel, real-time algorithm to accurately approximate the generalized penetration depth (
PD

g

) between two overlapping rigid or articulated models. Given the high complexity of computing
PD

g

, our algorithm approximates
PD

g

based on iterative, constrained optimization on the contact space, defined by the overlapping objects. The main ingredient of our algorithm is a novel and general formulation of distance metric, the
object norm
, in a configuration space for articulated models, and a compact closed-form solution for it. Then, we perform constrained optimization, by linearizing the contact constraint, and minimizing the object norm under such a constraint. In practice, our algorithm can compute locally optimal
PD

g

for rigid or articulated models consisting of tens of thousands of triangles in tens of milliseconds. We also suggest three applications using
PD

g

computation: retraction-based motion planning, physically-based animation, and data-driven grasping.
Diffusion pruning for rapidly and robustly selecting global correspondences using local isometry
Authors: Tam Gary K. L. , Martin Ralph R. , Rosin Paul L. , Lai Yu-Kun
Published: February 2014

Finding correspondences between two surfaces is a fundamental operation in various applications in computer graphics and related fields. Candidate correspondences can be found by matching local signatures, but as they only consider local geometry, many are globally inconsistent. We provide a novel algorithm to prune a set of candidate correspondences to those most likely to be globally consistent. Our approach can handle articulated surfaces, and ones related by a deformation which is globally nonisometric, provided that the deformation is locally approximately isometric. Our approach uses an efficient diffusion framework, and only requires geodesic distance calculations in small neighbourhoods, unlike many existing techniques which require computation of global geodesic distances. We demonstrate that, for typical examples, our approach provides significant improvements in accuracy, yet also reduces time and memory costs by a factor of several hundred compared to existing pruning techniques. Our method is furthermore insensitive to holes, unlike many other methods.
Oblivious bounds on the probability of boolean functions
Authors: Gatterbauer Wolfgang , Suciu Dan
Published: February 2014

This article develops upper and lower bounds for the probability of Boolean functions by treating multiple occurrences of variables as independent and assigning them new individual probabilities. We call this approach
dissociation
and give an exact characterization of
optimal oblivious bounds
, that is, when the new probabilities are chosen independently of the probabilities of all other variables. Our motivation comes from the
weighted model counting
problem (or, equivalently, the problem of computing the probability of a Boolean function), which is #P-hard in general. By performing several dissociations, one can transform a Boolean formula whose probability is difficult to compute into one whose probability is easy to compute, and which is guaranteed to provide an upper or lower bound on the probability of the original formula by choosing appropriate probabilities for the dissociated variables. Our new bounds shed light on the connection between previous relaxation-based and model-based approximations and unify them as concrete choices in a larger design space. We also show how our theory allows a standard relational database management system (DBMS) to both upper and lower bound hard probabilistic queries in guaranteed polynomial time.
Boosting monte carlo rendering by ray histogram fusion
Authors: Delbracio Mauricio , Musé Pablo , Buades Antoni , Chauvier Julien , Phelps Nicholas , Morel Jean-Michel
Published: February 2014

This article proposes a new multiscale filter accelerating Monte Carlo renderer. Each pixel in the image is characterized by the colors of the rays that reach its surface. The proposed filter uses a statistical distance to compare with each other the ray color distributions associated with different pixels, at each scale. Based on this distance, it decides whether two pixels can share their rays or not. This simple and easily reproducible algorithm provides apsnrgain of 10 to 15 decibels, or equivalently accelerates the rendering process by using 10 to 30 times fewer samples without observable bias. The algorithm is consistent, does not assume a particular noise model, and is immediately extendable to synthetic movies. Being based on the ray color values only, it can be combined with all rendering effects.
Fluid gesture interaction design
Authors: Zamborlin Bruno , Bevilacqua Frederic , Gillies Marco , D'inverno Mark
Published: February 2014

This article presents Gesture Interaction DEsigner (GIDE), an innovative application for gesture recognition. Instead of recognizing gestures only after they have been entirely completed, as happens in classic gesture recognition systems, GIDE exploits the full potential of gestural interaction by tracking gestures continuously and synchronously, allowing users to both control the target application moment to moment and also receive immediate and synchronous feedback about system recognition states. By this means, they quickly learn how to interact with the system in order to develop better performances. Furthermore, rather than learning the predefined gestures of others, GIDE allows users to design their own gestures, making interaction more natural and also allowing the applications to be tailored by users' specific needs. We describe our system that demonstrates these new qualities—that combine to provide fluid gesture interaction design—through evaluations with a range of performers and artists.
Efficient range searching for categorical and plain data
Authors: Nekrich Yakov
Published: February 2014

In the orthogonal range-searching problem, we store a set of input points
S
in a data structure; the answer to a query
Q
is a piece of information about points in
Q
∩
S
, for example, the list of all points in
Q
∩
S
or the number of points in
Q
. In the colored (or categorical) range-searching problem, the set of input points is partitioned into categories; the answer to a query is a piece of information about categories of points in a query range.

In this article, we describe several new results for one- and two-dimensional range-searching problems. We obtain an optimal adaptive data structure for counting the number of objects in a three-sided range and for counting categories of objects in a one-dimensional range. We also obtain new results on color range reporting in two dimensions, approximate color counting in one dimension, and some other related problems.
A Systematic Survey of Self-Protecting Software Systems
Authors: Yuan Eric , Esfahani Naeem , Malek Sam
Published: February 2014

Self-protecting software systems are a class of autonomic systems capable of detecting and mitigating security threats at runtime. They are growing in importance, as the stovepipe static methods of securing software systems have been shown to be inadequate for the challenges posed by modern software systems. Self-protection, like other self-* properties, allows the system to adapt to the changing environment through autonomic means without much human intervention, and can thereby be responsive, agile, and cost effective. While existing research has made significant progress towards autonomic and adaptive security, gaps and challenges remain. This article presents a significant extension of our preliminary study in this area. In particular, unlike our preliminary study, here we have followed a systematic literature review process, which has broadened the scope of our study and strengthened the validity of our conclusions. By proposing and applying a comprehensive taxonomy to classify and characterize the state-of-the-art research in this area, we have identified key patterns, trends and challenges in the existing approaches, which reveals a number of opportunities that will shape the focus of future research efforts.
Adaptive Epidemic Dynamics in Networks
Authors: Xu Shouhuai , Lu Wenlian , Xu Li , Zhan Zhenxin
Published: February 2014

Theoretical modeling of computer virus/worm epidemic dynamics is an important problem that has attracted many studies. However, most existing models are adapted from biological epidemic ones. Although biological epidemic models can certainly be adapted to capture some computer virus spreading scenarios (especially when the so-called homogeneity assumption holds), the problem of computer virus spreading is not well understood because it has many important perspectives that are not necessarily accommodated in the biological epidemic models. In this article, we initiate the study of such a perspective, namely that ofadaptivedefense against epidemic spreading in arbitrary networks. More specifically, we investigate a nonhomogeneous Susceptible-Infectious-Susceptible (SIS) model where the model parameters may vary with respect to time. In particular, we focus on two scenarios we callsemi-adaptivedefense andfully adaptivedefense, which accommodate implicit and explicit dependency relationships between the model parameters, respectively. In the semi-adaptive defense scenario, the model’s input parameters are given; the defense is semi-adaptive because the adjustment is implicitly dependent upon the outcome of virus spreading. For this scenario, we present a set of sufficient conditions (some are more general or succinct than others) under which the virus spreading will die out; such sufficient conditions are also known asepidemic thresholdsin the literature. In the fully adaptive defense scenario, some input parameters are not known (i.e., the aforementioned sufficient conditions are not applicable) but the defender can observe the outcome of virus spreading. For this scenario, we present adaptive control strategies under which the virus spreading will die out or will be contained to a desired level.
Constraint Satisfaction Problems Solvable by Local Consistency Methods
Authors: Barto Libor , Kozik Marcin
Published: February 2014

We prove that constraint satisfaction problems without the ability to count are solvable by the local consistency checking algorithm. This settles three (equivalent) conjectures: Feder--Vardi [SICOMP’98], Bulatov [LICS’04] and Larose--Zádori [AU’07].
Asymptotic series of generalized Lambert W function
Authors: Scott Tony C. , Fee Greg , Grotendorst Johannes
Published: February 2014

Herein, we present a sequel to earlier work on a generalization of the Lambert W function. In particular, we examine series expansions of the generalized version providing computational means for evaluating this function in various regimes and further confirming the notion that this generalization is a natural nextension of the standard Lambert W function.
Abstracts of recent doctoral dissertations in computer algebra
Authors: CCA editors
Published: February 2014

Each month we are pleased to present abstracts of recent doctoral dissertations in Computer Algebra and Symbolic Computation. We encourage all recent Ph.D. graduates (and their supervisors), who have defended in the past two years, to submit their abstracts for publication in CCA. Please send abstracts to the CCA editors editors_SIGSAM@acm.org for consideration.
Migration-based hybrid cache design for file systems over flash storage devices
Authors: Huang Po-Chun , Chang Yuan-Hao , Tsao Che-Wei , Yang Ming-Chang , Hsieh Cheng-Kang
Published: February 2014

This work is motivated by the urgent need to enhance the reliability of file systems in battery-powered mobile computing systems and consumer electronics that utilize flash storage devices for data storage. In this paper, we use non-volatile RAM (NVRAM) in the cache design because of its non-volatility and random byte addressability properties. Specifically, we propose a migration-based caching strategy that exploits NVRAM to enhance the reliability of file systems and to improve the access performance by utilizing the localities of accesses and the characteristics of flash storage devices. Our experimental results demonstrate that the proposed strategy can significantly improve the performance and reliability of file systems in flash storage devices.
Genealogical insights into the facts and fictions of clone removal
Authors: Zibran Minhaz F. , Saha Ripon K. , Roy Chanchal K. , Schneider Kevin A.
Published: February 2014

Clone management has drawn immense interest from the research community in recent years. It is recognized that a deep understanding of how code clones change and are refactored is necessary for devising effective clone management tools and techniques. This paper presents an empirical study based on the clone genealogies from a significant number of releases of nine software systems, to characterize the patterns of clone change and removal in evolving software systems. With a blend of qualitative analysis, quantitative analysis and statistical tests of significance, we address a number of research questions. Our findings reveal insights into the removal of individual clone fragments and provide empirical evidence in support of conventional clone evolution wisdom. The results can be used to devise informed clone management tools and techniques.
Obesity-metabolic derangement exacerbates cardiomyocyte loss distal to moderate coronary artery stenosis in pigs without affecting global cardiac function
Authors: Li Zi-Lun , Ebrahimi Behzad , Zhang Xin , Eirin Alfonso , Woollard John R. , Tang Hui , Lerman Amir , Wang Shen-Ming , Lerman Lilach O.
Published: February 2014

Obesity associated with metabolic derangements (ObM) worsens the prognosis of patients with coronary artery stenosis (CAS), but the underlying cardiac pathophysiologic mechanisms remain elusive. We tested the hypothesis that ObM exacerbates cardiomyocyte loss distal to moderate CAS. Obesity-prone pigs were randomized to four groups ( n = 6 each): lean-sham, ObM-sham, lean-CAS, and ObM-CAS. Lean and ObM pigs were maintained on a 12-wk standard or atherogenic diet, respectively, and left circumflex CAS was then induced by placing local-irritant coils. Cardiac structure, function, and myocardial oxygenation were assessed 4 wk later by computed-tomography and blood oxygenation level dependent (BOLD) MRI, the microcirculation with micro-computed-tomography, and injury mechanisms by immunoblotting and histology. ObM pigs showed obesity, dyslipidemia, and insulin resistance. The degree of CAS (range, 50–70%) was similar in lean and ObM pigs, and resting myocardial perfusion and global cardiac function remained unchanged. Increased angiogenesis distal to the moderate CAS observed in lean was attenuated in ObM pigs, which also showed microvascular dysfunction and increased inflammation (M1-macrophages, TNF-α expression), oxidative stress (gp91), hypoxia (BOLD-MRI), and fibrosis (Sirius-red and trichrome). Furthermore, lean-CAS showed increased myocardial autophagy, which was blunted in ObM pigs (downregulated expression of unc-51-like kinase-1 and autophagy-related gene-12; P < 0.05 vs. lean CAS) and associated with marked apoptosis. The interaction diet xstenosis synergistically inhibited angiogenic, autophagic, and fibrogenic activities. ObM exacerbates structural and functional myocardial injury distal to moderate CAS with preserved myocardial perfusion, possibly due to impaired cardiomyocyte turnover.
Activated alveolar epithelial cells initiate fibrosis through autocrine and paracrine secretion of connective tissue growth factor
Authors: Yang Jibing , Velikoff Miranda , Canalis Ernesto , Horowitz Jeffrey C. , Kim Kevin K.
Published: February 2014

Fibrogenesis involves a pathological accumulation of activated fibroblasts and extensive matrix remodeling. Profibrotic cytokines, such as TGF-β, stimulate fibroblasts to overexpress fibrotic matrix proteins and induce further expression of profibrotic cytokines, resulting in progressive fibrosis. Connective tissue growth factor (CTGF) is a profibrotic cytokine that is indicative of fibroblast activation. Epithelial cells are abundant in the normal lung, but their contribution to fibrogenesis remains poorly defined. Profibrotic cytokines may activate epithelial cells with protein expression and functions that overlap with the functions of active fibroblasts. We found that alveolar epithelial cells undergoing TGF-β-mediated mesenchymal transition in vitro were also capable of activating lung fibroblasts through production of CTGF. Alveolar epithelial cell expression of CTGF was dramatically reduced by inhibition of Rho signaling. CTGF reporter mice demonstrated increased CTGF promoter activity by lung epithelial cells acutely after bleomycin in vivo. Furthermore, mice with lung epithelial cell-specific deletion of CTGF had an attenuated fibrotic response to bleomycin. These studies provide direct evidence that epithelial cell activation initiates a cycle of fibrogenic effector cell activation during progressive fibrosis. Therapy targeted at epithelial cell production of CTGF offers a novel pathway for abrogating this progressive cycle and limiting tissue fibrosis.
High proliferative potential endothelial colony-forming cells contribute to hypoxia-induced pulmonary artery vasa vasorum neovascularization
Authors: Nijmeh Hala , Balasubramaniam Vivek , Burns Nana , Ahmad Aftab , Stenmark Kurt R. , Gerasimovskaya Evgenia V.
Published: February 2014

Angiogenic expansion of the vasa vasorum (VV) is an important contributor to pulmonary vascular remodeling in the pathogenesis of pulmonary hypertension (PH). High proliferative potential endothelial progenitor-like cells have been described in vascular remodeling and angiogenesis in both systemic and pulmonary circulations. However, their role in hypoxia-induced pulmonary artery (PA) VV expansion in PH is not known. We hypothesized that profound PA VV neovascularization observed in a neonatal calf model of hypoxia-induced PH is due to increased numbers of subsets of high proliferative cells within the PA adventitial VV endothelial cells (VVEC). Using a single cell clonogenic assay, we found that high proliferative potential colony-forming cells (HPP-CFC) comprise a markedly higher percentage in VVEC populations isolated from the PA of hypoxic (VVEC-Hx) compared with control (VVEC-Co) calves. VVEC-Hx populations that comprised higher numbers of HPP-CFC also demonstrated markedly higher expression levels of CD31, CD105, and c-kit than VVEC-Co. In addition, significantly higher expression of CD31, CD105, and c-kit was observed in HPP-CFC vs. the VVEC of the control but not of hypoxic animals. HPP-CFC exhibited migratory and tube formation capabilities, two important attributes of angiogenic phenotype. Furthermore, HPP-CFC-Co and some HPP-CFC-Hx exhibited elevated telomerase activity, consistent with their high replicative potential, whereas a number of HPP-CFC-Hx exhibited impaired telomerase activity, suggestive of their senescence state. In conclusion, our data suggest that hypoxia-induced VV expansion involves an emergence of HPP-CFC populations of a distinct phenotype with increased angiogenic capabilities. These cells may serve as a potential target for regulating VVEC neovascularization.
Systemic hydrogen sulfide administration partially restores normal alveolarization in an experimental animal model of bronchopulmonary dysplasia
Authors: Madurga Alicia , Mižíková Ivana , Ruiz-Camp Jordi , Vadász István , Herold Susanne , Mayer Konstantin , Fehrenbach Heinz , Seeger Werner , Morty Rory E.
Published: February 2014

Arrested alveolarization is the pathological hallmark of bronchopulmonary dysplasia (BPD), a complication of premature birth. Here, the impact of systemic application of hydrogen sulfide (H2S) on postnatal alveolarization was assessed in a mouse BPD model. Exposure of newborn mice to 85% O2 for 10 days reduced the total lung alveoli number by 56% and increased alveolar septal wall thickness by 29%, as assessed by state-of-the-art stereological analysis. Systemic application of H2S via the slow-release H2S donor GYY4137 for 10 days resulted in pronounced improvement in lung alveolarization in pups breathing 85% O2, compared with vehicle-treated littermates. Although without impact on lung oxidative status, systemic H2S blunted leukocyte infiltration into alveolar air spaces provoked by hyperoxia, and restored normal lung interleukin 10 levels that were otherwise depressed by 85% O2. Treatment of primary mouse alveolar type II (ATII) cells with the rapid-release H2S donor NaHS had no impact on cell viability; however, NaHS promoted ATII cell migration. Although exposure of ATII cells to 85% O2 caused dramatic changes in mRNA expression, exposure to either GYY4137 or NaHS had no impact on ATII cell mRNA expression, as assessed by microarray, suggesting that the effects observed were independent of changes in gene expression. The impact of NaHS on ATII cell migration was attenuated by glibenclamide, implicating ion channels, and was accompanied by activation of Akt, hinting at two possible mechanisms of H2S action. These data support further investigation of H2S as a candidate interventional strategy to limit the arrested alveolarization associated with BPD.
Detection and monitoring of localized matrix metalloproteinase upregulation in a murine model of asthma
Authors: Felsen Csilla N. , Savariar Elamprakash N. , Whitney Michael , Tsien Roger Y.
Published: February 2014

Extracellular proteases including matrix metalloproteinases (MMPs) are speculated to play a significant role in chronic lung diseases, such as asthma. Although increased protease expression has been correlated with lung pathogenesis, the relationship between localized enzyme activity and disease progression remains poorly understood. We report the application of MMP-2/9 activatable cell-penetrating peptides (ACPPs) and their ratiometric analogs (RACPPs) for in vivo measurement of protease activity and distribution in the lungs of mice that were challenged with the allergen ovalbumin. MMP-2/9 activity was increased greater than twofold in whole, dissected lungs from acutely challenged mice compared with control mice ( P = 1.8 × 10−4). This upregulation of MMP-2/9 activity was localized around inflamed airways with 1.6-fold higher protease-dependent ACPP uptake surrounding diseased airways compared with adjacent, pathologically normal lung parenchyma ( P = 0.03). MMP-2/9 activity detected by ACPP cleavage colocalized with gelatinase activity measured with in situ dye-quenched gelatin. For comparison, neutrophil elastase activity and thrombin activity, detected with elastase- and thrombin-cleavable RACPPs, respectively, were not significantly elevated in acutely allergen-challenged mouse lungs. The results demonstrate that ACPPs, like the MMP-2/9-activated and related ACPPs, allow for real-time detection of protease activity in a murine asthma model, which should improve our understanding of protease activation in asthma disease progression and help elucidate new therapy targets or act as a mechanism for therapeutic drug delivery.
An Active System for Visually-Guided Reaching in 3D across Binocular Fixations
Authors: Martinez-Martin Ester , del Pobil Angel P. , Chessa Manuela , Solari Fabio , Sabatini Silvio P.
Published: February 2014

Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity) generated from the egocentric representation of the visual information (image coordinates). In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching). The approach’s performance is evaluated through experiments on both simulated and real data.
Isolation of Intestinal Parasites of Public Health Importance from Cockroaches (Blattella germanica) in Jimma Town, Southwestern Ethiopia
Authors: Hamu Haji , Debalke Serkadis , Zemene Endalew , Birlie Belay , Mekonnen Zeleke , Yewhalaw Delenasaw
Published: February 2014

Cockroaches are claimed to be mechanical transmitters of disease causing microorganisms such as intestinal parasites, bacteria, fungi, and viruses. This study assessed the potential of the German cockroachBlattella germanicain the mechanical transmission of intestinal parasites of public health importance. A total of 2010 cockroaches were collected from 404 households in Jimma Town, southwestern Ethiopia. All the collected cockroaches were identified to species asB. germanica. The contents of their gut and external body parts were examined for the presence of intestinal parasites. Overall, 152 (75.6%) of the 210 batches were found to harbor at least one species of human intestinal parasite.Ascaris lumbricoides, Trichuris trichiura, Taenia spp, Strongyloides-like parasite,Entamoeba histolytica/dispar/moshkovski, Giardia duodenalisandBalantidium coliwere detected from gut contents. Moreover, parasites were also isolated from the external surface in 22 (10.95%) of the batches. There was significant difference in parasite carriage rate of the cockroaches among the study sites (P=0.013). In conclusion,B. germanicawas found to harbor intestinal parasites of public health importance. Hence, awareness on the potential role of cockroaches in the mechanical transmission of human intestinal parasites needs to be created. Moreover, further identification of the Strongyloides-like worm is required using molecular diagnostics.