bluuebunny/crossref_metadata_2025 huggingface dataset:
FUNCTIONAL PRINCIPAL COMPONENT ANALYSIS FOR RECOGNITION OF ARM GESTURES AND HUMANOID IMITATION
Authors: ALEOTTI JACOPO , CASELLI STEFANO
Published: February 2014

This paper investigates the use of functional principal component analysis (FPCA) for automatic recognition of dynamic human arm gestures and robot imitation. FPCA is a statistical technique of functional data analysis that generalizes standard multivariate principal component analysis. Functional data analysis signals (e.g., gestures) are functions that are considered as observations of a random variable on a functional space. In particular, FPCA reduces the dimensionality of the input data by projecting them onto a finite-dimensional space spanned by a few prominent eigenfunctions. The main contribution of this work is the proposal of a novel technique for unsupervised clustering of training data and dynamic gesture recognition based on FPCA. FPCA has not been considered in previous studies on humanoid learning. The proposed approach has been evaluated in two experimental settings for motion capture. In the first setup single arm gestures are recognized from inertial sensors attached to the arm of the user. In the second setup the method is extended to two-arm gestures acquired from a range sensor. Recognized gestures are reproduced by a small humanoid robot. The FPCA method has also been compared to a high performance algorithm for gesture classification based on dynamic time warping (DTW). The FPCA algorithm achieves comparable results in both recognition rate and robustness to missing data, while it outperforms DTW in terms of efficiency in execution time.
The Structure Theorem for Complete Intersections of Grade 4
Authors: Kang Oh-Jin , Ko Hyoung J.
Published: February 2014

Serre showed that a Gorenstein ideal of grade 2 is a complete intersection, and Buchsbaum and Eisenbud proved a structure theorem for Gorenstein ideals of grade 3. It is found that a certain complete matrix defines a perfect ideal [Formula: see text]. As an application, we present a structure theorem for complete intersections of grade 4.
Extensions of Generalized Reduced Rings
Authors: Hong Chan Yong , Kim Nam Kyun , Kwak Tai Keun
Published: February 2014

Anderson and Camillo studied the class of rings satisfying ZCn for n ≥ 2, which is a generalization of reduced rings. In this paper, we continue the study of such rings. We observe several extensions of rings satisfying ZCn. Rings satisfying the zero insertion property for n (simply, ZIn), which is a generalization of ZCn, are also introduced. In particular, we prove that every ring satisfying ZIn for some n ≥ 2 is a 2-primal ring. Furthermore, if R is an Armendariz ring satisfying ZIn for n ≥ 2, then the polynomial ring R[x] over R also satisfies ZIn.
Augmentation Quotients of Free Group Rings
Authors: Karan Ram , Kumar Deepak
Published: February 2014

Let F be a free group and R be a subgroup of F. It is proved that [Formula: see text] are free-abelian. Explicit bases of first two and complete descriptions of all these groups are also given.
On Conjugate-Permutable Subgroups of a Finite Group
Authors: Xu Mingyao , Zhang Qinhai
Published: February 2014

Let G be a finite group. A subgroup H of G is called conjugate-permutable in G if HHg = HgH for any g ∈ G. A group G is called an ECP-group if every subgroup of G is conjugate-permutable in G. In this paper, we study the influence of conjugate-permutable subgroups on the structure of a finite group, especially on the nilpotency or supersolvability of the group, and give some sufficient or necessary conditions for a finite group to be an ECP-group.
Elements with Square Roots in Finite Groups
Authors: Lucido M. S. , Pournaki M. R.
Published: February 2014

In this paper, we study the probability that a randomly chosen element in a finite group has a square root, in particular the simple groups of Lie type of rank 1, the sporadic finite simple groups and the alternating groups.
A Classification of Some Quadratic Algebras
Authors: McGilvray Heather C.
Published: February 2014

We investigate a group of quadratic algebras and the associated resolutions of the field. When the quadratic algebra is Koszul, we provide the associated linear resolution; when not Koszul, we describe the maps of the resolution up to the point of non-linearity. In all cases, the resolutions are shown to be surprisingly regular and quickly stabilizing.
On Strongly Groupoid Graded Rings and the Corresponding Clifford Theorem
Authors: Liu Gongxiang , Li Fang
Published: February 2014

In this paper, we introduce the definition of groupoid graded rings. Group graded rings, (skew) groupoid rings, artinian semisimple rings, matrix rings and others can be regarded as special kinds of groupoid graded rings. Our main task is to classify strongly groupoid graded rings by cohomology of groupoids. Some classical results about group graded rings are generalized to groupoid graded rings. In particular, the Clifford Theorem for a strongly groupoid graded ring is given.
A Note on Maps Characterized by Actions on Zero Products
Authors: Wang Yu
Published: February 2014

Let A and B be prime rings and θ: A→ B a bijective additive map such that θ(x) θ(y)=0 for all x, y∈ A with xy=0. Suppose that the maximal right quotient ring Q(A) of A contains a nontrivial idempotent e such that eA ∪ Ae ⊆ A. Then there exists λ ∈ C(B), the extended centroid of B, such that θ(xy) = λ θ(x) θ(y) for all x, y ∈ A. This removes the assumption deg (B)≥ 3 in the recent theorem due to Chebotar, Ke and Lee.
On Nonsingular Power LCM Matrices
Authors: Hong Shaofang , Shum K. P. , Sun Qi
Published: February 2014

Let e ≥ 1 be an integer and S={x1,…,xn} a set of n distinct positive integers. The matrix ([xi, xj]e) having the power [xi, xj]e of the least common multiple of xi and xj as its (i, j)-entry is called the power least common multiple (LCM) matrix defined on S. The set S is called gcd-closed if (xi,xj) ∈ S for 1≤ i, j≤ n. Hong in 2004 showed that if the set S is gcd-closed such that every element of S has at most two distinct prime factors, then the power LCM matrix on S is nonsingular. In this paper, we use Hong's method developed in his previous papers to consider the next case. We prove that if every element of an arbitrary gcd-closed set S is of the form pqr, or p2qr, or p3qr, where p, q and r are distinct primes, then except for the case e=1 and 270, 520 ∈ S, the power LCM matrix on S is nonsingular. We also show that if S is a gcd-closed set satisfying xi< 180 for all 1≤ i≤ n, then the power LCM matrix on S is nonsingular. This proves that 180 is the least primitive singular number. For the lcm-closed case, we establish similar results.
The Existence of p-Blocks of a Finite Group
Authors: Qian Fangsheng
Published: February 2014

Suppose G is a finite group and D is a normal p-subgroup of G with |D|=pd. Let GP denote the set of p-elements of G and Φ(g)={(a,b) ∈ GP× GP | ab=g}. We show that G has a p-block with D as a defect group if and only if there exists a p-regular element g of G with D as a Sylow p-subgroup of CG(g) such that |Φ(g)| ≠ 0 (mod pd+1).
R-Unipotent Congruences on Eventually Regular Semigroups
Authors: Luo Yanfeng , Li Xiaoling
Published: February 2014

A semigroup S is called an eventually regular semigroup if for every a ∈ S, there exists a positive integer n such that anis regular. In this paper, the R-unipotent, inverse semigroup and group congruences on an eventually regular semigroup S are described by means of certain congruence pairs (ξ, K), where ξ is a normal congruence on the subsemigroup 〈E(S)〉 generated by E(S), and K is a normal subsemigroup of S.
Sufficient Condition over the Number of Parity Checks for Burst Error Detection/Correction in Linear Lee Weight Codes
Authors: Jain Sapna , Shum K. P.
Published: February 2014

Lee weight is more appropriate for some practical situations than Hamming weight as it takes into account the magnitude of each digit of the word. In this paper, we obtain a sufficient bound over the number of parity check digits for codes detecting burst errors and also for codes correcting burst errors with Lee weight.
On Exchange QB∞-Rings
Authors: Chen Huanyin
Published: February 2014

In this paper, we introduce a new class of rings, the QB∞-rings. We investigate necessary and sufficient conditions under which an exchange ring is a QB∞-ring. The modules over an exchange QB∞-ring are studied. Also, we prove that every regular square matrix over an exchange QB∞-ring admits a diagonal reduction by pseudo-invertible matrices.
Direct Summands of ⊕-Supplemented Modules
Authors: Orhan Nil , Tütüncü Derya Keskin , Tribak Rachid
Published: February 2014

A module M is called ⊕-supplemented if every submodule of M has a supplement that is a direct summand of M. It is shown that if M is a ⊕-supplemented module and r(M) is a coclosed submodule of M for a left preradical r, then r(M) is a direct summand of M, and both r(M) and M/r(M) are ⊕-supplemented.
A q-Analogue of the Weyl–Kac Denominator Formulas of Types $\widetilde{F}_{41}$ and $\widetilde{G}_{21}$
Authors: Obul Abdukadir
Published: February 2014

By using Frobenius maps and F-stable representations, we give a q-analogue of the Weyl–Kac denominator formulas of types [Formula: see text] and [Formula: see text].
Quadratic and 2-Crossed Modules of Algebras
Authors: Arvasi Z. , Ulualan E.
Published: February 2014

In this work, we define the quadratic modules for commutative algebras and give relations among 2-crossed modules, crossed squares, quadratic modules and simplicial commutative algebras with Moore complex of length 2.
Local Homology, Cohen–Macaulayness and Cohen–Macaulayfications
Authors: Hellus Michael
Published: February 2014

Let (R,𝔪) be a local ring, X an artinian R-module of noetherian dimension d; let x1,…,xd ∈ 𝔪 be such that 0:X (x1,…,xd)R has finite length. We show by an example that [Formula: see text] is not finite as an R-module in general; it is finite if we assume R is complete. This answers a question posed by Tang. As a first application of the latter finiteness result, we give a necessary condition for a finite module to be Cohen–Macaulay; secondly we propose a notion of Cohen–Macaulayfication and prove its uniqueness; finally we show that this new notion of Cohen–Macaulayfication is a direct generalization of a notion of Cohen–Macaulayfication introduced by Goto.
A Generalization of Witt's Theorem and Sylvester's Law of Nullity
Authors: Wan Zhe-Xian
Published: February 2014

A generalization of Witt's theorem is given. The equivalence of the generalization of Witt's theorem over ℝ and Sylvester's law of nullity is proved.
Principal Ideal Multiplication Modules
Authors: Azizi A.
Published: February 2014

Let M be an R-module. If for every submodule N of M, there exists an element r ∈ R such that N=rM, then we say that M is a principal ideal multiplication module. In this paper, the relations between principal ideal multiplication modules, multiplication modules, cyclic modules, and modules over principal ideal rings are studied. It is proved that every principal ideal multiplication module over any quotient of a Dedekind domain is cyclic. Also, every principal ideal multiplication module with prime annihilator ideal is cyclic.
States and Boolean Algebra
Authors: Mikhaeel Nabila N. , Labib Basim Samir
Published: February 2014

We investigate subadditive measures on orthomodular lattices. We show as the main result that the Boolean algebra, the special metric orthomodular lattice and the orthomodular lattice which is unital with respect to subadditive states are equivalent. This result may find an application in the foundation of quantum theories and mathematical logic.
A Structure Theorem of Regular ${\cal H}^\sharp$-Cryptographs
Authors: Kong Xiangzhi , Yuan Zhiling , Shum K. P.
Published: February 2014

A new set of generalized Green relations is given in studying the [Formula: see text]-abundant semigroups. By using the generalized strong semilattice of semigroups recently developed by the authors, we show that an [Formula: see text]-abundant semigroup is a regular [Formula: see text]-cryptograph if and only if it is an [Formula: see text]-strong semilattice of completely [Formula: see text]-simple semigroups. This result not only extends the well known result of Petrich and Reilly from the class of completely regular semigroups to the class of semiabundant semigroups, but also generalizes a well known result of Fountain on superabundant semigroups from the class of abundant semigroups to the class of semiabundant semigroups.
Notes on More Fibonacci Groups
Authors: Jeong Kwang-Woo , Wang Moon-Ok
Published: February 2014

The Fibonacci manifolds Mn introduced by Helling, Kim and Mennicke are generalized in an obvious way suggested by a tessellation of triangles on the boundary of 3-balls. We construct an infinite family of hyperbolic 3-manifolds by a tessellation of (2ℓ +1)-gons on the boundary of a combinatorial polyhedron P(2ℓ +1, n). We prove that these manifolds are the n-fold cyclic branched coverings of S3 over the 2-bridge knot b(4ℓ2+1, 2ℓ), and investigate some topological and geometrical properties of the manifolds together with their first homology groups and split extensions.
Clusters in Non-simply-laced Finite Type via Frobenius Morphisms
Authors: Yang Dong
Published: February 2014

By showing the compatibility of folding almost positive roots and folding cluster categories, we prove that there is a one-to-one correspondence between seeds and tilting seeds in non-simply-laced finite type.
Simple Graphs and Zero-divisor Semigroups
Authors: Wu Tongsuo , Chen Li
Published: February 2014

In this paper, we provide examples of graphs which uniquely determine a zero-divisor semigroup. We show two classes of graphs that have no corresponding semigroups. Especially, we prove that no complete r-partite graph together with two or more end vertices (each linked to distinct vertices) has corresponding semigroups.
Second Cohomology of the Modular Lie Superalgebra of Cartan Type K
Authors: Xie Wenjuan , Zhang Yongzheng
Published: February 2014

Let 𝔽 be an algebraically closed field and char 𝔽 = p > 3. In this paper, we determine the second cohomology group of the finite-dimensional Contact superalgebra K(m,n,t).
Quantization of Lie Algebras of Generalized Weyl Type
Authors: Yue Xiaoqing , Jiang Qifen , Xin Bin
Published: February 2014

Recently, in [25], Lie bialgebra structures on Lie algebras of generalized Weyl type were considered, which are shown to be triangular coboundary. In this paper, we quantize these algebras with their Lie bialgebra structures.
Locally Finite Products of Totally Permutable Nilpotent Groups
Authors: De Falco Maria , de Giovanni Francesco , Musella Carmela
Published: February 2014

A group G=AB is said to be totally factorized by its subgroups A and B if XY=YX for all subgroups X of A and Y of B. It is known that any finite group totally factorized by supersoluble subgroups is supersoluble, and that a finite group totally factorized by nilpotent subgroups is abelian-by-nilpotent. This latter result is extended here to certain classes of infinite groups.
Structure of the Extended Schrödinger–Virasoro Lie Algebra $\widetilde{\mathfrak{sv}}$
Authors: Gao Shoulan , Jiang Cuipo , Pei Yufeng
Published: February 2014

We study the derivations, the central extensions and the automorphism group of the extended Schrödinger–Virasoro Lie algebra [Formula: see text], introduced by Unterberger in the context of two-dimensional conformal field theory and statistical physics. Moreover, we show that [Formula: see text] is an infinite-dimensional complete Lie algebra, and the universal central extension of [Formula: see text] in the category of Leibniz algebras is the same as that in the category of Lie algebras.
The Ideal Structure of Semigroups of Linear Transformations with Lower Bounds on Their Nullity or Defect
Authors: Mendes-Gonçalves Suzana , Sullivan R. P.
Published: February 2014

Suppose V is an infinite-dimensional vector space and let T(V) denote the semigroup (under composition) of all linear transformations of V. In this paper, we study the semigroup OM(p,q) consisting of all α ∈ T(V) for which dim ker α ≥ q and the semigroup OE(p,q) of all α ∈ T(V) for which codim ran α ≥ q, where dim V = p ≥ q ≥ ℵ0. It is not difficult to see that OM(p,q) and OE(p,q) are a right ideal and a left ideal of T(V), respectively, and using these facts, we show that they belong to the class of all semigroups whose sets of bi-ideals and quasi-ideals coincide. Also, we describe Green's relations and the two-sided ideals of each semigroup, and determine its maximal regular subsemigroup. Finally, we determine some maximal right cancellative subsemigroups of OE(p,q).
A Classification of 2-Finite Diagrams
Authors: Geng Shengfei , Peng Liangang
Published: February 2014

In this article, we give a classification of 2-finite diagrams by explicitly describing all diagrams of types A, B and D, and by listing all 2-finite diagrams of other types.
Finite p-Groups of Class 3 All of Whose Proper Sections Have Class at Most 2
Authors: Song Qiangwei , Qu Haipeng , Guo Xiuyun
Published: February 2014

In this paper, we give a characterization and a complete classification of minimal-class-3 p-groups, that is, the p-groups of class 3 all of whose proper sections have class at most 2.
Groups with Finitely Many Normalizers of Non-polycyclic Subgroups
Authors: De Falco Maria , de Giovanni Francesco , Musella Carmela
Published: February 2014

The structure of locally graded groups with finitely many normalizers of non-polycyclic subgroups is investigated. In particular, it is proved that such groups either are polycyclic or have Černikov commutator subgroups.
Classification of Z-Graded Modules of the Intermediate Series over the q-Analog Virasoro-like Algebra
Authors: Wu Yina , Lin Weiqiang
Published: February 2014

In this paper, we complete the classification of Z-graded modules of the intermediate series over a q-analog Virasoro-like algebra L. We first construct four classes of irreducible Z-graded L-modules of the intermediate series. Then we prove that any Z-graded L-module of the intermediate series must be one of the modules constructed by us, or a direct sum of some trivial L-modules.
Extreme Ranks of Real Matrices in Solution of the Quaternion Matrix Equation AXB = C with Applications
Authors: Wang Qingwen , Yu Shaowen , Xie Wei
Published: February 2014

In this paper, for a consistent quaternion matrix equation AXB = C, the formulas are established for maximal and minimal ranks of real matrices X1, X2, X3, X4 in solution X = X1 + X2i + X3j + X4k. A necessary and sufficient condition is given for the existence of a real solution of the quaternion matrix equation. The expression is also presented for the general solution to this equation when the solvability conditions are satisfied. Moreover, necessary and sufficient conditions are given for this matrix equation to have a complex solution or a pure imaginary solution. As applications, the maximal and minimal ranks of real matrices E, F, G, H in a generalized inverse (A +Bi + Cj + Dk)- = E + Fi + Gj + Hk of a quaternion matrix A + Bi + Cj + Dk are also considered. In addition, a necessary and sufficient condition is derived for the quaternion matrix equations A1XB1 = C1 and A2XB2 = C2 to have a common real solution.
Principal Blocks and the Steinberg Character
Authors: Hiss Gerhard
Published: February 2014

We determine the finite simple groups of Lie type of characteristic p, for which the Steinberg character lies in the principal ℓ-block for every prime ℓ ≠ p dividing the order of the group.
The Cyclic Subgroup Separability of Certain Generalized Free Products of Two Groups
Authors: Bobrovskii P. A. , Sokolov E. V.
Published: February 2014

Free products of two residually finite groups with amalgamated retracts are considered. It is proved that a cyclic subgroup of such a group is not finitely separable if, and only if, it is conjugated with a subgroup of a free factor which is not finitely separable in this factor. A similar result is obtained for the case of separability in the class of finite p-groups.
Algebraic Structure of TCI-Groupoids: Classes, Clones, Constructions
Authors: Gałuszka Jan
Published: February 2014

Some aspects of the algebraic structure of TCI-groupoids (totally commutative idempotent groupoids) are presented. Among other things, a full description of the corresponding binary clones is given. To investigate the algebraic structure of TCI-groupoids and their clones the families of two-generated subgroupoids are used. Next the algebraic structure of these families is studied in detail. We present a special construction which allows us to build each finite TCI-groupoid using the two-element semilattice as a kind of elementary "brick". Furthermore it is proved that the class of all regular TCI-groupoids satisfying binary nonbalanced identities is a nonaxiomatizable proper subclass of the class of all regular TCI-groupoids.
Conjugacy Classes of the 3-Braid Group
Authors: Ali Usman
Published: February 2014

In this article, we describe the summit sets in the 3-braid group, the smallest element in a summit set, and we compute the Hilbert series corresponding to conjugacy classes. The results are related to the Birman–Menasco classification of knots with braid index three or less than three.
The Structure of Almost Idempotent Semirings
Authors: Sen M. K. , Bhuniya A. K.
Published: February 2014

In this paper we introduce the notion of almost idempotent semirings as the semirings with semilattice additive reduct satisfying the identity x + x2= x2, and characterize eight subclasses of the variety [Formula: see text] of all almost idempotent semirings corresponding to the eight subvarieties of the variety [Formula: see text] of all normal bands. Every almost idempotent semiring S is a distributive lattice of rectangular almost idempotent semirings. Given a semigroup F, the semiring Pf(F) of all finite non-empty subsets of F is almost idempotent precisely when F is a band, and in this case, Pf(F) is freely generated by the band F in the variety [Formula: see text]. This semiring Pf(F) is free in a subclass of [Formula: see text] if and only if F is in the corresponding subvariety of [Formula: see text].
On Generalized (α,β)-Derivations in Prime Rings
Authors: Marubayashi Hidetoshi , Ashraf Mohammad , Rehman Nadeem-ur , Ali Shakir
Published: February 2014

Let R be a ring and α,β be endomorphisms of R. An additive mapping F: R → R is called a generalized (α,β)-derivation on R if there exists an (α,β)-derivation d: R → R such that F(xy)=F(x) α(y) + β(x)d(y) holds for all x, y ∈ R. In the present paper, we discuss the commutativity of a prime ring R admitting a generalized (α,β)-derivation F satisfying any one of the properties: (i) [F(x),x]α,β=0, (ii) F([x,y])=0, (iii) F(x ◦ y)=0, (iv) F([x,y])=[x,y]α,β, (v) F(x ◦ y)=(x ◦ y)α,β, (vi) F(xy)- α(xy) ∈ Z(R), (vii) F(x)F(y)- α(xy) ∈ Z(R) for all x, y in an appropriate subset of R.
Vertex Weighted Complexities of Graph Coverings
Authors: Wu Hongfeng , Feng Rongquan , Sato Iwao
Published: February 2014

In this paper the vertex weighted complexity of a graph is considered. A generalization of Northshield's Theorem for the vertex weighted complexity of a graph is presented. Furthermore, an explicit formula for the vertex weighted complexity of a covering graph of G in terms of that of G is given.
Canonical Forms of Indecomposable Modules over K[x,y]/(xp,yq,xy)
Authors: Liu Genqiang , Zhang Yingbo
Published: February 2014

Let Λ=K[x,y]/(xp,yq,xy) be a Gelfand–Ponomarev algebra, where p,q ∈ ℕ, and [Formula: see text] the matrix problem of Λ. In the present paper, we determine the canonical forms of indecomposable modules of Λ, and give a one-to-one correspondence between the iso-classes of the modules over Λ and the canonical forms over [Formula: see text]. Finally, we discuss some properties of the module variety of Λ using the canonical forms.
Homomorphisms of Matrix Semigroups over Division Rings from Dimension Two to Three
Authors: Dolinar Gregor , Marovt Janko
Published: February 2014

Let 𝔻 be an arbitrary division ring and Mn(𝔻) the multiplicative semigroup of all n × n matrices over 𝔻. We describe the general form of non-degenerate homomorphisms from M2(𝔻) to M3(𝔻).
Proper LeftGC-lppSemigroups and a Generalized Version of McAlister's P-Theorem
Authors: Guo Xiaojiang , Shum K. P.
Published: February 2014

In this paper, we describe the structure of proper left GC-lpp semigroups. Our main result not only generalizes a result of Takizawa on E-unitary [Formula: see text]-unipotent semigroups but also those of Fountain and Gomes on proper left ample semigroups. Ultimately, we extend McAlister's P-theorem, a fundamental structure theorem of inverse semigroups.
Evaluation of Gauss Sums for 2-Power Order in Index 4
Authors: Yang Jing , Feng Keqin
Published: February 2014

Let χ be a character of order N=2t(t ⩾ 4) over a finite field 𝔽q = 𝔽pf with p ≡ 7, 9 (mod 16). In this paper, we evaluate explicitly the Gauss sums G(χr) related to the group generated by the character χ.
The Upper Radical Property and Lower Radical Property of Groups
Authors: Zhang Zhirang , Li Xuemei
Published: February 2014

We take in this paper an arbitrary class [Formula: see text] of groups as a base, and define a radical property 𝒫 for which every group in [Formula: see text] is 𝒫-semisimple. This is called the upper radical property determined by the class [Formula: see text]. At the same time, we define a radical property 𝒫 for which every group in [Formula: see text] is a 𝒫-radical group. This is called the first lower radical property determined by the class [Formula: see text]. Also, we give another construction leading to the second lower radical property which is proved to be identical with the first one.
New Simple Algebras Containing the Matrix Ring
Authors: Lee Jongwoo , Nam Ki-Bong
Published: February 2014

We define the combinatorial simple algebras N(eAS,n,t)k, N(eAS,n,t)k+and N(eAS,n,t)[k]which contain both the matrix ring and the non-associative algebras discussed in [11]. We also define a new cyclic finite dimensional algebra which contains the matrix ring Mn(𝔽) and show that the algebra is simple (see [3] and [7]). Even more, we find the automorphism group of the algebra N(0,n,t)[1]and show that the general matrix group GLn+t(𝔽) is not a subgroup of the automorphism group Aut (N(0,n,t)[1]).
Projective Envelopes of Finitely Generated Modules
Authors: Parra Rafael , Rada Juan
Published: February 2014

A well known problem in the theory of envelopes is to characterize those rings having the property that every (finitely generated, finitely presented, simple) module has a projective (pre)envelope. In this paper, we introduce the [Formula: see text]-projective modules for an arbitrary class [Formula: see text] of finitely generated modules, and characterize in this general setting those rings for which every module in [Formula: see text] has a projective preenvelope.
On Free and Weak Free (Semi)Hypergroups
Authors: Mousavi S. Sh. , Jafarpour M.
Published: February 2014

In this paper, first we show that the categories of semihypergroups and hypergroups have not free objects. Next we give the notion of weak free semihypergroups for the classes of semihypergroups and extension complete semihypergroups (ECS). Also, we give a necessary and sufficient condition for a semihypergroup for being weak free semihypergroups in the category ECS. Finally, the existence of proper weak free objects in ECS is proved.
Almost Commutative Semigroups
Authors: Ahmadidelir K. , Campbell C. M. , Doostie H.
Published: February 2014

The commutativity degree of groups and rings has been studied by certain authors since 1973, and the main result obtained is [Formula: see text], where Pr (A) is the commutativity degree of a non-abelian group (or ring) A. Verifying this inequality for an arbitrary semigroup A is a natural question, and in this paper, by presenting an infinite class of finite non-commutative semigroups, we prove that the commutativity degree may be arbitrarily close to 1. We name this class of semigroups the almost commutative or approximately abelian semigroups.
A Note on Martindale Lemma
Authors: Xu Xiaowei , Ma Jing , Niu Fengwen
Published: February 2014

In 1969, Martindale proved a famous theorem well known as the Martindale lemma. In this paper, we give a generalization of the Martindale lemma by considering the nonlinear case.
Octo-bialgebras
Authors: Ni Xiang , Bai Chengming
Published: February 2014

The notion of octo-algebra was introduced by Leroux as a Loday algebra with 8 operations. In this paper, we introduce a notion of octo-bialgebra as a bialgebra theory of octo-algebras, which is equivalent to a double construction of a quadri-algebra with a nondegenerate 2-cocycle or a double construction of an octo-algebra with a nondegenerate invariant bilinear form. Some properties of octo-bialgebras are given, including the study of the coboundary cases which leads to a construction from an analogue of the classical Yang-Baxter equation in an octo-algebra.
A ℤ-Basis for the Cluster Algebra of Type $\widetilde{D}_4$
Authors: Ding Ming , Xu Fan
Published: February 2014

We deduce a ℤ-basis for the cluster algebra of type [Formula: see text]. It extends the results obtained by Caldero and Keller, as well as Sherman and Zelevinsky. Moreover, we prove that coefficients of Laurent expansions in the generalized cluster variables for [Formula: see text] are positive integers.
Subalgebras of the Lie Algebra of the Derivations on a Torus and Their Representations
Authors: Tang Xiaomin
Published: February 2014

We study a class of subalgebras of the Lie algebra of the derivations on a torus. We construct a functor Fα from linear Lie algebra modules to these subalgebra modules. We then characterize the structure of the image modules of corresponding linear Lie algebra modules under this functor.
Nilpotent Elements and Skew Polynomial Rings
Authors: Alhevaz A. , Moussavi A. , Hashemi E.
Published: February 2014

We study the structure of the set of nilpotent elements in extended semicommutative rings and introduce nil α-semicommutative rings as a generalization. We resolve the structure of nil α-semicommutative rings and obtain various necessary or sufficient conditions for a ring to be nil α-semicommutative, unifying and generalizing a number of known commutative-like conditions in special cases. We also classify which of the standard nilpotence properties on polynomial rings pass to skew polynomial ring. Constructing various examples, we classify how the nil α-semicommutative rings behaves under various ring extensions. Also, we consider the nil-Armendariz condition on a skew polynomial ring.
Complete Intersection Flat Dimension and the Intersection Theorem
Authors: Sahandi Parviz , Sharif Tirdad , Yassemi Siamak
Published: February 2014

Any finitely generated module M over a local ring R is endowed with a complete intersection dimension CI-dim RM and a Gorenstein dimension G-dim RM. The Gorenstein dimension can be extended to all modules over the ring R. This paper presents a similar extension for the complete intersection dimension, and mentions the relation between this dimension and the Gorenstein flat dimension. In addition, we show that in the intersection theorem, the flat dimension can be replaced by the complete intersection flat dimension.
Some Constructions of Bi-Koszul Algebras
Authors: Si Junru , Lü Jiafeng
Published: February 2014

Bi-Koszul algebras, including two classes of non-Koszul Artin-Schelter regular algebras of global dimension 4, were a class of graded algebras with non-pure resolutions, introduced in [8]. There is a natural question: can we construct bi-Koszul algebras from algebras with pure resolutions? In this paper, we study this question in terms of normal extensions and Ore extensions. More precisely, we attempt to obtain bi-Koszul algebras from algebras with pure resolutions by these two kinds of extensions. Furthermore, some homological properties of bi-Koszul algebras obtained in such ways are discussed.
On Hyperbolic Clifford Algebras with Involution
Authors: Mahmoudi M. G.
Published: February 2014

The aim of this article is to provide a characterization of quadratic forms of low dimension such that the canonical involutions of their Clifford algebras are hyperbolic.
Group Gradings on Finite Dimensional Lie Algebras
Authors: Pagon Dušan , Repovš Dušan , Zaicev Mikhail
Published: February 2014

We study gradings by non-commutative groups on finite dimensional Lie algebras over an algebraically closed field of characteristic zero. It is shown that if L is graded by a non-abelian finite group G, then the solvable radical R of L is G-graded and there exists a Levi subalgebra B=H1⊕ ⋯ ⊕ Hm homogeneous in G-grading with graded simple summands H1,…,Hm. All Supp Hi (i=1,…,m) are commutative subsets of G.
On the Attached Primes and Shifted Localization Principle for Local Cohomology Modules
Authors: An Tran Nguyen
Published: February 2014

Let (R,𝔪) be a Noetherian local ring and M a finitely generated R-module. For an integer i ≥ 0, the Artinian i-th local cohomology module [Formula: see text] is said to satisfy the shifted localization principle if [Formula: see text] for all 𝔭 ∈ Spec (R). In this paper we study the attached primes of [Formula: see text] and give some conditions for [Formula: see text] to satisfy the shifted localization principle.
On K2 of 𝔽p[Cp2× Cp2]
Authors: Chen Hong , Gao Yubin , Tang Guoping
Published: February 2014

In this paper, through the calculation of K2(𝔽pCp2[t]/(tp2),(t)) using Dennis-Stein symbols, we determine the explicit structure of K2(𝔽p[Cp2 × Cp2]) and give its basis in Steinberg symbols.
Portable XRF and wet materials: application to dredged contaminated sediments from waterways
Authors: Lemiere Bruno , Laperche Valerie , Haouche Laurence , Auger Pascal
Published: February 2014

The sustainable management of dredged waterway sediments requires on-site determination of the main pollutants to facilitate their safe reuse or treatment. Portable X-ray fluorescence (pXRF) is commonly used for similar applications with contaminated soil, but the high water content of dredged sediments precludes any application of standard methods. Measurements for Pb, Zn, Cu and As were performed on-site on raw wet sediments with 50 to 70 % water contents during dredging or mapping operations. These results, although two or three times lower than laboratory analyses on the same samples, were found to be related to absolute concentrations closely enough to rank samples. In order to investigate further the feasibility of field analyses on wet sediments, partial dehydration methods were tested. The most efficient technique is based on a hand press. It is simple and quick enough to be used on dredging boats during operations and produces sample pellets with 30 to 50 % water contents. The relationship between pXRF measurements on these pellets and laboratory analyses was found to be sufficiently linear to calculate estimated concentrations. Potential differences were found to be less than 20 % for Pb and Zn. Higher differences for Cu were due to very low concentrations, within twice the limit of detection (LOD). Some limitations were observed. The water content in pellets is variable depending on the sediment type or matrix. The correction factors vary between the measured elements and they may also vary with matrix chemistry. However, Pb-Zn-Cu-As concentrations were ranked and evaluated accurately and the geochemical signatures of the samples were preserved.

We demonstrated that, with a simple partial dehydration procedure, pXRF measurements can be reliably related closely enough to absolute concentrations to make field decisions for sediment management. Since the approximately linear relationships between measurements on semi-wet samples and laboratory analyses are matrix- and site-dependent, they must be recognised before using pXRF on wet samples for decision-making.
Cotransfection with IL-10 and TGF-β1 into immature dendritic cells enhances immune tolerance in a rat liver transplantation model
Authors: Chen Lihong , Zheng Lin , He Wubing , Qiu Minglian , Gao Lingyun , Liu Jingfeng , Huang Aimin
Published: February 2014

Dendritic cells transfected with interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) enhance T cell immunity and tolerance. However, no quantitative studies have investigated the suppressive functions of immature dendritic cells (imDC) cotransfected with IL-10 and TGF-β1. The effects of imDC cotransfected with IL-10 and TGF-β1 (IL-10-TGF-β1-imDC) on immune tolerance induction in a rat transplantation model were investigated. In addition, effects of IL-10-TGF-β1-imDC relative to IL-10-transfected imDC (IL-10-imDC) and TGF-β1-transfected imDC (TGF-β1-imDC) were compared. The infusion of IL-10-TGF-β1-imDC into recipients prolonged liver graft survival, which was sustained for >90 days. IL-12 serum levels decreased, whereas alanine transaminase and total bilirubin slightly increased in rats infused with IL-10-TGF-β1-imDC compared with the IL-10-imDC and TGF-β1-imDC groups. Furthermore, a higher percentage of terminal transferase-mediated UTP nick end-labeling-positive cells was observed, and histological analysis of the allografts indicated a rejection activity index of mild acute rejection. Our results suggest infusion of IL-10 and TGF-β1 cotransfected imDC induces alloantigen-specific T cell hyporesponsiveness, inhibits antigen-specific immunological responses to liver allografts, prolongs liver allograft survival, and enhances the immune tolerance. This approach may provide a promising alternative for enhancing donor-specific tolerance during liver transplantation.
Regulation of renalase expression by D5 dopamine receptors in rat renal proximal tubule cells
Authors: Wang Shaoxiong , Lu Xi , Yang Jian , Wang Hongyong , Chen CaiYu , Han Yu , Ren Hongmei , Zheng Shuo , He Duofen , Zhou Lin , Asico Laureano D. , Wang Wei Eric , Jose Pedro A. , Zeng Chunyu
Published: February 2014

The dopaminergic and sympathetic systems interact to regulate blood pressure. Our previous studies showed regulation of α1-adrenergic receptor function by D1-like dopamine receptors in vascular smooth muscle cells. Because renalase could regulate circulating epinephrine levels and dopamine production in renal proximal tubules (RPTs), we tested the hypothesis that D1-like receptors regulate renalase expression in kidney. The effect of D1-like receptor stimulation on renalase expression and function was measured in immortalized RPT cells from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs). We found that the D1-like receptor agonist fenoldopam (10−7–10−5 mol/l) increased renalase protein expression and function in WKY RPT cells but decreased them in SHR cells. Fenoldopam also increased renalase mRNA levels in WKY but not in SHR cells. In contrast, fenoldopam increased the degradation of renalase protein in SHR cells but not in WKY cells. The regulation of renalase by the D1-like receptor was mainly via the D5 receptor because silencing of the D5 but not D1 receptor by antisense oligonucleotides blocked the stimulatory effect of the D1-like receptor on renalase expression in WKY cells. Moreover, inhibition of PKC, by the PKC inhibitor 19–31, blocked the stimulatory effect of fenoldopam on renalase expression while stimulation of PKC, by a PKC agonist (PMA), increased renalase expression, indicating that PKC is involved in the process. Our studies suggest that the D5 receptor positively regulates renalase expression in WKY but not SHR RPT cells; aberrant regulation of renalase by the D5 receptor may be involved in the pathogenesis of hypertension.
Electrophysiological and morphological properties of rat supratrigeminal premotor neurons targeting the trigeminal motor nucleus
Authors: Nakamura Shiro , Nakayama Kiyomi , Mochizuki Ayako , Sato Fumihiko , Haque Tahsinul , Yoshida Atsushi , Inoue Tomio
Published: February 2014

The electrophysiological and morphological characteristics of premotor neurons in the supratrigeminal region (SupV) targeting the trigeminal motor nucleus (MoV) were examined in neonatal rat brain stem slice preparations with Ca2+ imaging, whole cell recordings, and intracellular biocytin labeling. First, we screened SupV neurons that showed a rapid rise in intracellular free Ca2+ concentration ([Ca2+]i) after single-pulse electrical stimulation of the ipsilateral MoV. Subsequent whole cell recordings were generated from the screened SupV neurons, and their antidromic responses to MoV stimulation were confirmed. We divided the antidromically activated premotor neurons into two groups according to their discharge patterns during the steady state in response to 1-s depolarizing current pulses: those firing at a frequency higher (HF neurons, n = 19) or lower (LF neurons, n = 17) than 33 Hz. In addition, HF neurons had a narrower action potential and a larger afterhyperpolarization than LF neurons. Intracellular labeling revealed that the axons of all HF neurons (6/6) and half of the LF neurons (4/9) entered the MoV from its dorsomedial aspect, whereas the axons of the remaining LF neurons (5/9) entered the MoV from its dorsolateral aspect. Furthermore, the dendrites of three HF neurons penetrated into the principal sensory trigeminal nucleus (Vp), whereas the dendrites of all LF neurons were confined within the SupV. These results suggest that the types of SupV premotor neurons targeting the MoV with different firing properties have different dendritic and axonal morphologies, and these SupV neuron classes may play unique roles in diverse oral motor behaviors, such as suckling and mastication.
Sensory reweighting dynamics in human postural control
Authors: Assländer Lorenz , Peterka Robert J.
Published: February 2014

Healthy humans control balance during stance by using an active feedback mechanism that generates corrective torque based on a combination of movement and orientation cues from visual, vestibular, and proprioceptive systems. Previous studies found that the contribution of each of these sensory systems changes depending on perturbations applied during stance and on environmental conditions. The process of adjusting the sensory contributions to balance control is referred to as sensory reweighting. To investigate the dynamics of reweighting for the sensory modalities of vision and proprioception, 14 healthy young subjects were exposed to six different combinations of continuous visual scene and platform tilt stimuli while sway responses were recorded. Stimuli consisted of two components: 1) a pseudorandom component whose amplitude periodically switched between low and high amplitudes and 2) a low-amplitude sinusoidal component whose amplitude remained constant throughout a trial. These two stimuli were mathematically independent of one another and, thus, permitted separate analyses of sway responses to the two components. For all six stimulus combinations, the sway responses to the constant-amplitude sine were influenced by the changing amplitude of the pseudorandom component in a manner consistent with sensory reweighting. Results show clear evidence of intra- and intermodality reweighting. Reweighting dynamics were asymmetric, with slower reweighting dynamics following a high-to-low transition in the pseudorandom stimulus amplitude compared with low-to-high amplitude shifts, and were also slower for inter- compared with intramodality reweighting.
Anatomy and Histochemistry of Roots and Shoots in Wild Rice (Zizania latifolia Griseb.)
Authors: Yang Chaodong , Zhang Xia , Li Junkai , Bao Manzhu , Ni Dejiang , Seago James L.
Published: February 2014

Wild rice (Zizania latifolia Griseb.) is a famous, perennial, emergent vegetable in China. The current work explores the anatomy and histochemistry of roots, stems, and leaves and the permeability of apoplastic barriers of wild rice. The adventitious roots in wild rice have suberized and lignified endodermis and adjacent, thick-walled cortical layers and suberized and lignified hypodermis, composed of a uniseriate sclerenchyma layer (SC) underlying uniseriate exodermis; they also have lysigenous aerenchyma. Stems have a thickened epidermal cuticle, a narrow peripheral mechanical ring (PMR), an outer ring of vascular bundles, and an inner ring of vascular bundles embedded in a multiseriate sclerenchyma ring (SCR). There is evidence of suberin in stem SCR and PMR sclerenchyma cells. Sheathing leaves are characterized by thick cuticles and fibrous bundle sheath extensions. Air spaces in stems and leaves consist of mostly lysigenous aerenchyma and pith cavities in stems. Apoplastic barriers are found in roots and stems.
Synthesis of Nickel and Nickel Hydroxide Nanopowders by Simplified Chemical Reduction
Authors: Tientong Jeerapan , Garcia Stephanie , Thurber Casey R. , Golden Teresa D.
Published: February 2014

Nickel nanopowders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at pH ~12.5. Sonication of the solutions created a temperature of 54–65°C to activate the reduction reaction of nickel nanoparticles. The solution pH affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (pH~10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.
Quality of Life in Patients with Focal Hyperhidrosis before and after Treatment with Botulinum Toxin A
Authors: Kouris Anargyros , Armyra Kalliopi , Christodoulou Christos , Karimali Polixeni , Karypidis Dimitrios , Kontochristopoulos George
Published: February 2014

The aim of this study is to assess the effectiveness of treatment with BTX-A in quality of life of patients suffering from primary focal hyperhidrosis. Materials and Methods. A total of 119 patients (62 females and 57 males) between 18 and 65 years suffering from moderate to severe focal hyperhidrosis were treated with BTX-A. Thirty-nine patients suffered from axillary hyperhidrosis, 47 patients from palmar hyperhidrosis, 12 patients from plantar hyperhidrosis, and 21 patients from palmar and plantar hyperhidrosis. A baseline and posttreated examination of patients 6 months after BTX-A is included. The Hyperhidrosis Disease Severity Scale (HDSS) was chosen to assess the disease severity and the modified Dermatology Life Quality Index was used (DLQI) to assess the quality of life. Results. Quality of life showed a significant improvement after treatment with BTX-A. The total DLQI score resulted significantly lower than the basal value (P<0.0001). The seriousness of hyperhidrosis significantly decreased after the treatment (P<0.0001). In addition, there was notable difference between the posttreatment DLQI scores and pretreatment severity of hyperhidrosis by sex. Conclusions. Treatment with BTX-A led to the reduction of disease severity and improvement of quality of life, while it is a safe, easy to use method with minimal side effects.