bluuebunny/crossref_metadata_2025 huggingface dataset:
Star chromatic numbers and products of graphs
Authors: Zhu Xuding
Published: June 2007

The star‐chromatic number of a graph, a concept introduced by Vince, is natural generalization of the chromatic number of a graph. We point out an alternate definition of the star‐chromatic number, which sheds new light on the relation of the star‐chromatic number and the ordinary chromatic number. This new point of view allows us to answer several problems posed by Vince. We then study the starchromatic number from the perspective of graph homomorphisms and of graph products.
Edge‐disjoint paths and cycles in n‐edge‐connected graphs
Authors: Huck Andreas
Published: June 2007

We consider finite undirected loopless graphs G in which multiple edges are possible. For integers k,l ≥ 0 let g(k, l) be the minimal n ≥ 0 with the following property: If G is an n‐edge‐connected graph, s1, ⃛,sk, t1, ⃛,tk are vertices of G, and f1, ⃛,fl, g1, ⃛,gl, are pairwise distinct edges of G, then for each i = 1, ⃛, k there exists a path Pi in G, connecting si and ti and for each i = 1, ⃛,l there exists a cycle Ci in G containing fi and gi such that P1, ⃛,Pk, C1, ⃛, Cl are pairwise edge‐disjoint. We give upper and lower bounds for g(k, l).
The connectivity of large digraphs and graphs
Authors: Fiol M. A.
Published: June 2007

This paper studies the relation between the connectivity and other parameters of a digraph (or graph), namely its order n, minimum degree δ, maximum degree Δ, diameter D, and a new parameter lpi;, 0 ≤ π ≤ δ − 2, related with the number of short paths (in the case of graphs l0 = ⌊(g − 1)/2⌋ where g stands for the girth). For instance, let G = (V,A) be a digraph on n vertices with maximum degree Δ and diameter D, so that n ≤ n(Δ, D) = 1 + Δ + Δ 2 + … + ΔD (Moore bound). As the main results it is shown that, if κ and λ denote respectively the connectivity and arc‐connectivity of G,
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Analogous results hold for graphs. © 1993 John Wiley & Sons, Inc.
Perfect k‐line graphs and k‐total graphs
Authors: Lê Van Bang
Published: June 2007

The concept of the line graph can be generalized as follows. The k‐line graph Lk(G) of a graph G is defined as a graph whose vertices are the complete subgraphs on k vertices in G. Two distinct such complete subgraphs are adjacent in Lk(G) if and only if they have in G k − 1 vertices in common. The concept of the total graph can be generalized similarly. Then the Perfect Graph Conjecture will be proved for 3‐line graphs and 3‐total graphs. Moreover, perfect 3‐line graphs are not contained in any of the known classes of perfect graphs. © 1993 John Wiley & Sons, Inc.
On sparse subgraphs preserving connectivity properties
Authors: Frank András , Ibaraki Toshihide , Nagamochi Hiroshi
Published: June 2007

From a theorem of W. Mader [“Über minimal n‐fach zusammenhängende unendliche Graphen und ein Extremal problem,” Arch. Mat., Vol. 23 (1972), pp. 553–560] it follows that a k‐connected (k‐edge‐connected) graph G = (V,E) always contains a k‐connected (k‐edge‐connected) subgraph G′ = (V,E′) with O(k|V|) edges. T. Nishizeki and S. Poljak “K‐Connectivity and Decomposition of Graphs into Forests,” Discrete Applied Mathematics, submitted) showed how G′ can be constructed as the union of k forests. H. Nagamochi and T. Ibaraki [A Linear Time Algorithm for Finding a Sparse k‐Connected Spanning Subgraph of a k‐Connected Graph, Algorithmica, Vol. 7 (1992), pp. 583–596] constructed such a subgraph Gk in linear time and showed for any pair x,y of nodes that Gk contains k openly disjoint (edge‐disjoint) paths connecting x and y if G contains k openly disjoint (edge‐disjoint) paths connecting x and y (even if G is not k‐connected (k‐edge‐connected)). In this article we provide a much shorter proof of a common generalization of the edge‐ and node‐connectivity versions showing that the subgraph Gk has a certain mixed connectivity property. © 1993 John Wiley & Sons, Inc.
Maximal independent sets in bipartite graphs
Authors: Liu Jiuqiang
Published: June 2007

A maximal independent set of a graph G is an independent set that is not contained properly in any other independent set of G. In this paper, we determine the maximum number of maximal independent sets among all bipartite graphs of order n and the extremal graphs as well as the corresponding results for connected bipartite graphs. © 1993 John Wiley & Sons, Inc.
Independence and graph homomorphisms graph homomorphisms
Authors: Albertson Michael O. , Chan Lily , Haas Ruth
Published: June 2007

A graph with n vertices that contains no triangle and no 5‐cycle and minimum degree exceeding n/4 contains an independent set with at least (3n)/7 vertices. This is best possible. The proof proceeds by producing a homomorphism to the 7‐cycle and invoking the No Homomorphism Lemma. For k ≥ 4, a graph with n vertices, odd girth 2k+1, and minimum degree exceeding n/(k+1) contains an independent set with at least kn/(2k+1) vertices; however, we suspect this is not best possible. © 1993 John Wiley & Sons, Inc.
There is no universal countable pentagon‐free graph
Authors: Cherlin G. , Komjáth P.
Published: June 2007

No countable Cn‐free graph contains every countable Cn‐free graph as a subgraph, for n ≧ 4. For n = 4, this was proved earlier by J. Pach.
Contractions to k8
Authors: Jørgensen Leif K.
Published: June 2007

It is proved that the maximal number of edges in a graph with n ≧ 8 vertices that is not contractible to K8 is 6n − 21, unless 5 divides n, and the only graphs with n = 5m vertices and more than 6n − 21 edges that are not contractible to K8 are the K5(2)‐cockades that have exactly 6n − 20 edges.
Almost claw‐free graphs
Authors: Ryjáček Zdeněk
Published: June 2007

We say that G is almost claw‐free if the vertices that are centers of induced claws (K1,3) in G are independent and their neighborhoods are 2‐dominated. Clearly, every claw‐free graph is almost claw‐free. It is shown that (i) every even connected almost claw‐free graph has a perfect matching and (ii) every nontrivial locally connected K1,4‐free almost claw‐free graph is fully cycle extendable.
Which generalized petersen graphs are cayley graphs?
Authors: Nedela Roman , Škoviera Martin
Published: June 2007

The generalized Petersen graph GP (n, k), n ≤ 3, 1 ≥ k < n/2 is a cubic graph with vertex‐set {uj; i ϵ Zn} ∪ {vj; i ϵ Zn}, and edge‐set {uiui, uivi, vivi+k, iϵZn}. In the paper we prove that

(i) GP(n, k) is a Cayley graph if and only if k2  1 (mod n); and

(ii) GP(n, k) is a vertex‐transitive graph that is not a Cayley graph if and only if k2  ‐1 (mod n) or (n, k) = (10, 2), the exceptional graph being isomorphic to the 1‐skeleton of the dodecahedon.

The proof of (i) is based on the classification of orientable regular embeddings of the n‐dipole, the graph consisting of two vertices and n parallel edges, while (ii) follows immediately from (i) and a result of R. Frucht, J.E. Graver, and M.E. Watkins [“The Groups of the Generalized Petersen Graphs,” Proceedings of the Cambridge Philosophical Society, Vol. 70 (1971), pp. 211‐218]. © 1995 John Wiley & Sons, Inc.
On the maximum number of edges in a c4‐free subgraph of qn
Authors: Brass Peter , Harborth Heiko , Nienborg Hauke
Published: June 2007

For the maximum number f(n) of edges in a C4‐free subgraph of the n‐dimensional cube‐graph Qn we prove f(n) ≥ 1/2(n +√n)2n−1 for n = 4r, and f(n) ≥ 1/2(n +0.9√n)2n−1 for all n ≥ 9. This disproves one version of a conjecture of P. Erdos. © 1995 John Wiley & Sons, Inc.
Retract‐collapsible graphs and invariant subgraph properties
Authors: Polat Norbert
Published: June 2007

A (finite or infinite) graph G is retract‐collapsible if it can be dismantled by deleting systematically at each step every vertex that is strictly dominated, in such a way that the remaining subgraph is a retract of G, and so as to get a simplex at the end. A graph is subretract‐collapsible if some graph obtained by planting some rayless tree at each of its vertices is retract‐collapsible. It is shown that the subretract‐colapsible graphs are cop‐win; and that a ball‐Helly graph is subretract‐collapsible if and only if it has no isometric infinite paths (thus in particular if it has no infinite paths, or if it is bounded). Several fixed subgraph properties are proved. In particular, if G is a subretract‐collapsible graph, and f a contraction from G into G, then (i) if G has no infinite simplices, then f(S) = S for some simplex S of G; and (ii) if the dismantling of G can be achieved in a finite number of steps and if some family of simplices of G has a compacity property, then there is a simplex S of G such that f(S) ⊆ S. This last result generalizes a property of bounded ball‐Helly graphs. © 1995 John Wiley & Sons, Inc.
Factorization of regular multigraphs into regular graphs
Authors: El‐Zanati S. I. , Plantholt M. J. , Tipnis S. K.
Published: June 2007

A regular multigraph with maximum multiplicity r and degree rs cannot always be factored into r s‐regular simple graphs. It is shown, however, that under general conditions a similar factorization can be achieved if we first allow the addition or deletion of a relatively small number of hamilton cycles. Based on this result, we give extensions of some known factorization results on simple graphs to new results on multigraphs. © 1995 John Wiley & Sons, Inc.
Generalized steinhaus graphs
Authors: Brand Neal , Morton Margaret
Published: June 2007

A generalized Steinhaus graph of order n and type s is a graph with n vertices whose adjacency matrix (ai,j) satisfies the relation magnified image where 2 ≦i≦n−1, i + s(i − 1 ≦ j ≦ n, cr,i,j ϵ {0,1} for all 0 ≦ r ≦ s(i) −1 and cs(i)−1,i,j = 1. The values of s(i) and cr,i,j are fixed but arbitrary. Generalized Steinhaus graphs in which each edge has probability ½ are considered. In an article by A. Blass and F. Harary [“Properties of Almost All Graphs and Complexes,” Journal of Graph Theory, Vol. 3 (1976), pp. 225–240], a collection of first‐order axioms are given from which any first‐order property in graph theory or its negation can be deduced. We show that almost all generalized Steinhaus graphs satisfy these axioms. Thus the first‐order theory of random generalized Steinhaus graphs is identical with the theory of random graphs. Quasi‐random properties of graphs are described by F. R. K. Chung, R. L. Graham, and R. M. Wilson, [“Quasi‐Random Graphs,” Combinatorica, Vol. 9 (1989), pp. 345–362]. We conclude by demonstrating that almost all generalized Steinhaus graphs obey Property 2 and hence all equivalent quasi‐random properties. © 1996 John Wiley & Sons, Inc.
Asymptotic enumeration of full graphs
Authors: Kleitman D. J. , Lasaga F. R. , Cowen L. J.
Published: June 2007

A full graph on n vertices, as defined by Fulkerson, is a representation of the intersection and containment relations among a system of n sets. It has an undirected edge between vertices representing intersecting sets, and a directed edge from a to b if the corresponding set A contaisn B. We give a unified argument to show that asymptotically, almost all full graphs can be obtained by taking an arbitrary undirected graph in the n vertices, distinguishing a clique in this graph that need not be maximal, and then adding directed edges going out from each vertex in the clique to all vertices to which there is not already an existing undirected edge. © 1996 John Wiley & Sons, Inc.
A circular‐arc characterization of certain rectilinear drawings
Authors: Stueckle S. K. , Piazza B. L. , Ringeisen R. D.
Published: June 2007

In this paper we give a construction that produces exactly those graphs having maximum rectilinear crossing number equal to the subthrackle bound. We then prove a theorem characterizing these graphs in terms of proper circular‐arc graphs. © 1996 John Wiley & Sons, Inc.
From steiner centers to steiner medians
Authors: Oellermann Ortrud R.
Published: June 2007

The Steiner distance of set S of vertices in a connected graph G is the minimum number of edges in a connected subgraph of G containing S. For n ≥ 2, the Steiner n‐eccentricity en(v) of a vertex v of a graph G is the maximum Steiner distance among all sets S of n vertices of G that contain v. The Steiner n‐center of G is the subgraph induced by those vertices of G having minimum n‐eccentricity. The Steiner n‐distance of a vertex v of G is defined as magnified image. The Steiner n‐median of G is the subgraph of G induced by the vertices of G of minimum Steiner n‐distance. Known algorithms for finding the Steiner n‐centers and Steiner n‐medians of trees are used to show that the distance between the Steiner n‐centre and Steiner n‐median of a tree can be arbitrarily large. Centrality measures that allow every vertex on a shortest path from the Steiner n‐center to the Steiner n‐median of a tree to belong to the “center” with respect to one of these measures are introduced and several proeprties of these centrality measures are established. © 1995 John Wiley & Sons, Inc.
Degree‐bounded coloring of graphs: Variations on a theme by brooks
Authors: Hakimi S. L. , Mitchem J. , Schmeichel E. F.
Published: June 2007

A graph G is degree‐bounded‐colorable (briefly, db‐colorable) if it can be properly vertex‐colored with colors 1,2, …, k ≤ Δ(G) such that each vertex v is assigned a color c(v) ≤ v. We first prove that if a connected graph G has a block which is neither a complete graph nor an odd cycle, then G is db‐colorable. One may think of this as an improvement of Brooks' theorem in which the global bound Δ(G) on the number of colors is replaced by the local bound deg v on the color at vertex v. Extending the above result, we provide an algorithmic characterization of db‐colorable graphs, as well as a nonalgorithmic characterization of db‐colorable trees. We briefly examine the problem of determining the smallest integer k such that G is db‐colorable with colors 1, 2,…, k. Finally, we extend these results to set coloring. © 1995, John Wiley & Sons, Inc.
Note on irreducible triangulations of surfaces
Authors: Nakamoto Atsuhiro , Ota Katsuhiro
Published: June 2007

In this paper, we shall show that an irreducible triangulation of a closed surface F2 has at most cg vertices, where g stands for a genus of F2 and c a constant. © 1995, John Wiley & Sons, Inc.
Hamiltonicity of 5‐Connected Toroidal Triangulations
Authors: Brunet Richard , Richter R. Bruce
Published: June 2007

In this article, we prove that a 5‐connected toroidal triangulation has a contractible Hamilton cycle. © 1995 John Wiley & Sons, Inc.
Bipartite multigraphs with 1‐factors containing specified edges
Authors: Allen S. M.
Published: June 2007

We prove a necessary and sufficient condition for a regular bipartite multigraph to contain a 1‐factor including one specified set of independent edges and avoiding another specified set of edges. © 1995 John Wiley & Sons, Inc.
An induced subgraph characterization of domination perfect graphs
Authors: Zvervich Igor E. , Zverovich Vadim E.
Published: June 2007

Let γ(G) ι(G) be the domination number and independent domination number of a graph (G), respectively. A graph (G) is called domination perfect if γ(H) = ι(H), for every induced subgraph H of (G). There are many results giving a partial characterization of domination perfect graphs. In this paper, we present a finite induced subgraph characterization of the entire class of domination perfect graphs. The list of forbidden subgraphs in the charcterization consists of 17 minimal domination imperfect graphs. Moreover, the dominating set and independent dominating set problems are shown to be both NP‐complete on some classes of graphs. © 1995 John Wiley & Sons, Inc.
Hamiltonicity for K1, r‐free graphs
Authors: Chen Guantao , Schelp R. H.
Published: June 2007

In this paper, we investigate the Hamiltonicity of K1,r‐free graphs with some degree conditions. In particular, let G be a k‐connected grph of order n≧3 which is K1,4‐free. If magnified image for every independent set {v0, v1, …, vk} then G is hamiltonian. We use an upper bound for the independence number of K1,r‐free graphs to extent the above result to K1,r‐free graphs. Hamiltonian connected and, more generally, q‐edge hamiltonian properties are studied here as well. © 1995 John Wiley & Sons, Inc.
A note on coverings of plane graphs
Authors: Rivera‐Campo Eduardo
Published: June 2007

For any plane graph G the number of edges in a minimum edge covering of the faces of G is at most the vertex independence number of G and the numbre of vertices in a minimum vertex covering of the faces of G is at most the edge independence number of G. © 1995 John Wiley & Sons, Inc.
Hamiltonian cycles in 2‐connected claw‐free‐graphs
Authors: Li Hao
Published: June 2007

M. Matthews and D. Sumner have proved that of G is a 2‐connected claw‐free graph of order n such that δ ≧ (n − 2)/3, then G is hamiltonian. We prove that the bound for the minimum degree δ can be reduced to n/4 under the additional condition that G is not in F, where F is the set of all graphs defined as follows: any graph H in F can be decomposed into three vertex disjoint subgraphs H1, H2, H3 such that magnified image, where ui, vi ϵ V(Hi), uj vj ϵ V(Hj) 1 ϵ i ≦ j ≦ 3. Examples are given to show that the bound n/4 is sharp. © 1995 John Wiley & Sons, Inc.
Cycles through particular subgraphs of claw‐free graphs
Authors: Broersma H. J. , Lu M.
Published: June 2007

Let G be a 2‐connected claw‐free graph on n vertices, and let H be a subgraph of G. We prove that G has a cycle containing all vertices of H whenever α3(H) ≧ κ(G), where α3(H) denotes the maximum number of vertices of H that are pairwise at distance at least three in G, and κ(G) denotes the connectivity of G. This result is an analog of a result from the thesis of Fournier, and generalizes the result of Zhang that G is hamiltonian if the degree sum of any κ(G) + 1 pairwise nonadjacent vertices is at least n − κ(G). © 1995 John Wiley & Sons, Inc.
Perfect and locally perfect colorings
Authors: Rusu Irena
Published: June 2007

We present a new algorithm for coloring perfect graphs and use it to color the parity orderable graphs, a class which strictly contains parity graphs. Also, we modify this algorithm to obtain an O(m2 + n) locally perfect coloring algorithm for parity graphs. © 1995 John Wiley & Sons, Inc.
Are disc pressure, stress, and osmolarity affected by intra‐ and extrafibrillar fluid exchange?
Authors: Schroeder Yvonne , Sivan Sarit , Wilson Wouter , Merkher Yulia , Huyghe Jacques M. , Maroudas Alice , Baaijens Frank P.T.
Published: June 2007

Because extrafibrillar water content dictates extrafibrillar osmolarity, we aimed to determine the influence of intra‐ and extrafibrillar fluid exchange on intradiscal pressures and stresses. As experimental results showed that extrafibrillar osmolarity affects intervertebral disc cell gene expression and crack propagation, quantification of the effects of changes in intra‐ and extrafibrillar fluid exchange is physiologically relevant. Therefore, our 3D osmoviscoelastic finite element (FE) model of the intervertebral disc was extended to include the intra‐ and extrafibrillar water differentiation. Two simulations were performed, one without intrafibrillar fluid and one with intrafibrillar fluid fraction as a function of the extrafibrillar osmotic pressure. The intrafibrillar fluid fraction as a function of the extrafibrillar osmotic pressure was exponentially fitted to human data and implemented into the model. Because of the low collagen content in the nucleus, no noticeable differences in intradiscal pressure estimation were observed. However, values of extrafibrillar osmolarity, hydrostatic pressure, and the total tissue stress calculated for the annulus were clearly different. Stresses, hydrostatic pressure, and osmolarity were underestimated when the intrafibrillar water value was neglected. As the loading increased, the discrepancies increased. In conclusion, the distribution of pressure and osmolarity in the disc is affected by intra‐ and extrafibrillar water exchange. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1317–1324, 2007
Postoperative serum attenuates LPS‐induced release of TNF‐α in orthopaedic surgery
Authors: Reikerås Olav , Sun Jingbo , Wang Jacob E. , Aasen Ansgar O.
Published: June 2007

Studies with ex vivo stimulation of whole blood samples from injured patients have revealed a diminished production capacity for a broad range of secretory products, including inflammatory cytokines. Recent interest has focused on the release of mediators in serum that depress the cell‐mediated immune response following trauma. The involvement of the lipid mediator prostaglandin E2 (PGE2) has been assumed because it is a potent endogenous immunosuppressor. In the present study, we tested the hypothesis that inhibitory substances circulating in the patient's serum after a major musculoskeletal trauma might impair leukocyte function by evaluating the effect of such serum on cytokine release in a whole blood model. Six females and three males undergoing elective total hip replacement were included in the study. Ex vivo LPS‐induced TNF‐α and IL‐10 were measured in whole blood sampled preoperatively and added serum taken before, at the end of operation, and at postoperative days 1 and 6 with saline as negative control. LPS induced significant releases of TNF‐α and IL‐10 in whole blood. Addition of preoperative, postoperative, and day‐1 postoperative serum did not alter the LPS‐induced release of TNF‐α as compared to saline. In the presence of serum from postoperative day 6, however, the expression of TNF‐α was significantly reduced as compared to saline and preoperative serum (p = 0.021 and 0.008, respectively). Neither of the serum samples altered the release of IL‐10. PGE2 was significantly (p = 0.008) increased in serum at postoperative day 6 as compared to preoperative levels. In conclusion, these data show that at day 6 after major orthopaedic surgery, the patient serum contained activity that inhibited ex vivo LPS‐induced TNF‐α release. The potent TNF‐α inhibitory activity found at day 6 after injury correlated with increased levels of PGE2 and indicates cell‐mediated hyporesponsiveness to a second stimulus. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1395–1400, 2007
Nonpharmacological treatment, fludrocortisone, and domperidone for orthostatic hypotension in Parkinson's disease
Authors: Schoffer Kerrie L. , Henderson Robert D. , O'Maley Karen , O'Sullivan John D.
Published: June 2007

There is limited evidence for the treatment of orthostatic hypotension in idiopathic Parkinson's disease. The objective of this study was to determine the efficacy of three treatments (nonpharmacological therapy, fludrocortisone, and domperidone). Phase I assessed the compliance, safety, and efficacy of nonpharmacological measures. Phase II was a double‐blind randomized controlled crossover trial of the two medications. Primary outcome measures consisted of the orthostatic domain of the Composite Autonomic Symptom Scale (COMPASS‐OD), a clinical global impression of change (CGI), and postural blood pressure testing via bedside sphygmomanometry (Phase I) or tilt table testing (Phase II). For the 17 patients studied, nonpharmacological therapy did not significantly alter any outcome measure. Both medications improved the CGI and COMPASS‐OD scores. There was a trend towards reduced blood pressure drop on tilt table testing, with domperidone having a greater effect. © 2007 Movement Disorder Society
Clinical correlates of mitochondrial function in Huntington's disease muscle
Authors: Turner Christopher , Cooper J. Mark , Schapira Anthony H. V.
Published: June 2007

Huntington's disease (HD) is caused by an abnormally expanded CAG repeat in the IT‐15 gene, which encodes a widely expressed protein called huntingtin. Abnormalities of mitochondrial respiratory chain function, specifically complex II/III, have been identified in HD striatum and defects of energy metabolism have been demonstrated in vivo in skeletal muscle in both symptomatic and presymptomatic HD patients. We have investigated respiratory chain function using histochemical and biochemical methods in HD skeletal muscle from 12 patients and compared these with 12 age and sex‐matched controls. The data from the HD patients were related to clinical parameters of HD including the Unified Huntington's Disease Rating Scale (UHDRS). There were positive correlations between CAG repeat years (a product of CAG repeat length and age) and both motor (P < 0.002) and cognitive (P < 0.01) scores of the UHDRS. There was no significant difference in the activities of complexes I to IV compared to age‐matched controls. However, there were significant correlations for individual HD complex II/III activities with disease duration (P = 0.017), repeat years (P = 0.032), and cognitive scores (P = 0.019). There was also evidence from ultrastructural studies that inclusion formation may occur in HD muscle. These results provide additional evidence that mutant huntingtin influences mitochondrial complex II/III function in non‐neuronal tissue (skeletal muscle) and suggest that muscle may be a potential marker of disease progression in HD. © 2007 Movement Disorder Society
Motor cortex stimulation for levodopa‐resistant akinesia: Case report
Authors: Tani Naoki , Saitoh Youichi , Kishima Haruhiko , Oshino Satoru , Hatazawa Jun , Hashikawa Kazuo , Yoshimine Toshiki
Published: June 2007

We treated a patient with levodopa‐resistant akinesia with motor cortex stimulation (MCS), and she showed dramatic improvement more than 1 year. On admission, the patient presented severe akinesia and gait disturbance without tremor and rigidity, and did not respond to levodopa test. The patient was suspected pure akinesia and progressive supranuclear palsy. First, high‐frequency rTMS of primary motor cortex was examined, and showed the dramatic improvement. Next, chronic subdural electrodes were implanted over the motor cortex bilaterally. One year after surgery, the Unified Parkinson's Disease Rating Scale had improved remarkably, and she could walk four times faster than before. The H215O PET study showed a significant increase of rCBF in the left SMA and right dorsolateral prefrontal cortex after bilateral MCS. MCS may be an alternative treatment for patients with akinesia, including those with PD, and particularly for levodopa‐resistant patients, who respond well to rTMS. © 2007 Movement Disorder Society
Effects of chronic subthalamic stimulation on nonmotor fluctuations in Parkinson's disease
Authors: Witjas Tatiana , Kaphan Elsa , Régis Jean , Jouve Elisabeth , Chérif André Ali , Péragut Jean‐Claude , Azulay Jean Philippe
Published: June 2007

The aim of this study was to assess the outcome of nonmotor fluctuations (NMF) after chronic Subthalamic nucleus (STN) Deep Brain Stimulation (DBS) in Parkinson's disease(PD). Chronic stimulation of the STN has proved to be an effective treatment for advanced PD with motor complications. The outcome of NMF, which are also disabling, remains unknown. Forty‐patients underwent bilateral STN stimulation. Each patient was interviewed before and after 1 yr of STN DBS with a structured questionnaire about their NMF. After 1 yr of chronic stimulation, the improvement in the motor score (UPDRS III) and dyskinesia amounted respectively to 67.4 and 76.3%. The decrease in motor fluctuations (MF) was 59% and 13 patients reported that their MF had disappeared. Comparatively, a reduction of the total number of NMF was also observed (mean number preoperatively: 15.6 per patient, postoperatively: 6.6). Most of the nonmotor fluctuating symptoms occurred in the “off” state preoperatively and no longer depended on the patient's motor state after surgery. The improvement in NMF was not identical for the different categories: pain/sensory fluctuations showed the best response to STN DBS (84.2%). Dysautonomic and cognitive fluctuations were also markedly improved (>60%) while psychic fluctuations remained the most frequent postoperative NMF observed. Some incapacitating manifestations such as drenching sweats and akathisia showed a remarkably good response to STN stimulation. In conclusion STN DBS alleviates NMF. It has strikingly successful effects on sensory, dysautonomic and cognitive fluctuations. However, psychic fluctuations respond less consistently to this treatment. © 2007 Movement Disorder Society
Dopaminergic modulation of timing control and variability in the gait of Parkinson's disease
Authors: Almeida Quincy J. , Frank James S. , Roy Eric A. , Patla Aftab E. , Jog Mandar S.
Published: June 2007

The basal ganglia have been implicated in timing control, yet the nature of timing disturbances in Parkinson's disease (PD) is poorly understood. We evaluated the influence of timing cues on spatiotemporal aspects of gait control and its variability, and the impact of dopaminergic treatment on timing. Three separate groups: 19 PD (OFF state); 24 PD (ON state); and 30 control participants were tested. Participants walked on a computerized carpet at four randomized and metronome‐controlled rates: self‐paced, 60, 80, or 100 steps/min. To our knowledge, this is the first study to demonstrate that medicated PD patients had poorer timing control than patients withdrawn from medication and healthy participants when modulating timing to an external stimulus. Increased step‐to‐step timing variability and deficits in mean temporal gait characteristics revealed that the medicated PD group (in contrast to nonmedicated PD group) performed least like healthy participants. This was observable in externally‐cued conditions, but not during self‐paced gait. Similar to previous research, step length contributed to overall slowness in PD, while temporal characteristics of gait did not. Interestingly, healthy participants increased stride length with each increase in cue rate, whereas both PD groups locked their step length regardless of temporal demand. Step‐to‐step variability differences between PD and healthy (e.g. step and double‐support time measurements) may be indicative of specific basal ganglia involvement in temporal control of gait. © 2007 Movement Disorder Society
Free latissimus dorsi perforator flap for reconstruction of hemifacial atrophy: Case report
Authors: Suominen Erkki A. , Niemi Tarja S. , Koskivuo Ilkka O. , Brück Nina M. , Saaristo Anne M.
Published: June 2007

Progressive hemifacial atrophy (PHA) is characterized by slow and progressive atrophy usually of one side of the face. PHA affects primarily the subcutaneous fat and muscle tissues, but may involve the bone. The cause is unknown. The treatment is symptomatic and directed at augmentation of the deficient soft‐tissue volume. The reconstructive procedures may combine fat grafts, dermis fat grafts, pedicle flaps, bone grafts, microvascular free flaps, and alloplastic implants. We report a patient with of PHA whose condition was treated with a free latissimus dorsi (LD) perforator flap. The LD perforator flap was suitable for the large defect of the patient. It could easily be tailored and thinned to follow the facial contour. Minor revisions were needed for esthetic reasons. There was neither significant downward gravitation nor wasting of the flap. 23 months later, the natural appearance of the face was maintained. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
Microsurgical nonmicrovascular flaps in forearm and hand reconstruction
Authors: Georgescu Alexandru V. , Matei Ileana , Ardelean Filip , Capota Irina
Published: June 2007

Relatively new method in flap's surgery, perforator flaps tends to monopolize nowadays the surgeon's interest. The question is: could these flaps be used not only as free flaps, as were mainly used until now, but also as local or regional flaps? On the basis of our experience with 115 operated cases, we will try to demonstrate that a lot of simple or composite defects in the forearm and hand could be covered, in selected cases, by using local or regional perforator flaps. This may have as result, in the future, a dramatic decrease in the indication for free flap transfers. Because these flaps need a microsurgical dissection, but do not need microvascular sutures, they could be defined as “microsurgical nonmicrovascular flaps.” The main advantages of these flaps could be summarized as: no microsurgical sutures, no main vascular pedicles sacrifice, same surgical field, shorter hospitalization time. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
Heuristic analysis of the complete symmetry group and nonlocal symmetries for some nonlinear evolution equations
Authors: Myeni S. M. , Leach P. G. L.
Published: June 2007

The complete symmetry group of a 1 + 1 evolution equation has been demonstrated to be represented by the six‐dimensional Lie algebra of point symmetries sl(2, R) ⊕sW, where W is the three‐dimensional Heisenberg–Weyl algebra. We construct a complete symmetry group of a nonlinear heat equation ut= F(ux)uxx for some smooth functions F, using the point symmetries admitted by each equation. The nonlinear heat equation is not specifiable by point symmetries alone even when the number of symmetries is 6. We report Ansätze which provide a route to the determination of the required nonlocal symmetry necessary to supplement the point symmetries for the complete specification of these nonlinear 1 + 1 evolution equations. The nonlocal symmetry immediately realized is said to be generic to a class of equations as it gives a specific structure to an equation. Copyright © 2007 John Wiley & Sons, Ltd.
Ecdysteroids from the medicinal fern Microsorum scolopendria (Burm. f.)
Authors: Snogan Eva , Vahirua‐Lechat Isabelle , Ho Raimana , Bertho Gildas , Girault Jean‐Pierre , Ortiga Sophie , Maria Annick , Lafont René
Published: June 2007

Fronds of the fern Microsorum scolopendria are widely used in traditional medicine in the Society Islands. They were investigated for the presence of ecdysteroids, which might be responsible for at least some of their medicinal properties. M. scolopendria represents an excellent source of ecdysone (0.16% of dry weight) and 20‐hydroxyecdysone (0.20%), and also contains significant amounts (0.01–0.02%) of makisterones A and C, inokosterone and amarasterone A, together with lower amounts of poststerone and of a compound tentatively identified as 24,28‐diepi‐cyasterone. During this study, three new minor phytoecdysteroids, namely 20‐deoxymakisterone A, a 25(?)‐epimer of amarasterone A and 25‐deoxyecdysone 22‐glucoside were also isolated by a combination of normal‐ and reversed‐phase HPLC and subsequently identified by NMR. Copyright © 2007 John Wiley & Sons, Ltd.
Why is late‐onset Huntington disease under‐diagnosed?
Authors: Teodorczuk Andrew
Published: June 2007

Huntington disease is still under‐diagnosed by neurologists and psychiatrists –particularly in the elderly population. Dr Teodorczuk explores the reasons for under‐diagnosis and misdiagnosis and provides an update on the features of Huntington disease with an emphasis on late‐onset disease. Copyright © 2007 Wiley Interface Ltd
Structure, flexibility, and mechanism of the Bacillus stearothermophilus RecU holliday junction resolvase
Authors: Kelly Stephen J. , Li Jie , Setlow Peter , Jedrzejas Mark J.
Published: June 2007

Here we report a high resolution structure of RecU‐Holliday junction resolvase from Bacillus stearothermophilus. The functional unit of RecU is a homodimer that contains a “mushroom” like structure with a rigid cap and two highly flexible loops extending outwards. These loops appear to be highly flexible/dynamic, and presumably are directly involved in DNA binding and holding it for catalysis. Structural modifications of both the protein and DNA upon their interaction are essential for catalysis. An Mg2+ ion is present in each of the two active sites in this homodimeric enzyme, and two water molecules are coordinated with each Mg2+ ion. Our data are consistent with one of these water molecules acting as a nucleophile and the other as a general acid. The identities of the general base and general acid involved in catalysis and the Lewis acid that stabilizes the pentacovalent transition state phosphate ion are proposed. A model for the RecU‐Holliday junction DNA complex is also proposed and discussed in thecontext of DNA binding and cleavage. Proteins 2007. © 2007 Wiley‐Liss, Inc.
A consensus algorithm to screen genomes for novel families of transmembrane β barrel proteins
Authors: Garrow Andrew G. , Westhead David R.
Published: June 2007

The ability to search sequence datasets for membrane spanning proteins is an important requirement for genome annotation. However, the development of algorithms to identify novel types of transmembrane β‐barrel (TMB) protein has proven substantially harder than for transmembrane helical proteins, owing to a shorter TM domain in which only alternate residues are hydrophobic. Although recent reports have described important improvements in the development of such algorithms, there is still concern over their ability to confidently screen genomes. Here we describe a new algorithm combining composition and hidden Markov model topology based classifiers (called TMB‐Hunt2), which achieves a crossvalidation accuracy of >95%, with 96.7% precision and 94.2% recall. An overview is given of the algorithm design, with a thorough assessment of performance and application to a number of genomes. Of particular note is that TMB/extracellular protein discrimination is significantly more difficult than TMB/cytoplasmic protein discrimination, with the predictor correctly rejecting just 74% of extracellular proteins, in comparison to 98% of cytoplasmic proteins. Focus is given to directions for further improvements in TMB/non‐TMB protein discrimination, with a call for the development of standardized tests and assessments of such algorithms. Tools and datasets are made available through a website called TMB‐Web (http://www.bioinformatics.leeds.ac.uk/TMB‐Web/TMB‐Hunt2). Proteins 2007. © 2007 Wiley‐Liss, Inc.
Classification and functional annotation of eukaryotic protein kinases
Authors: Miranda‐Saavedra Diego , Barton Geoffrey J.
Published: June 2007

Reversible protein phosphorylation by protein kinases and phosphatases is a ubiquitous signaling mechanism in all eukaryotic cells. A multilevel hidden Markov model library is presented which is able to classify protein kinases into one of 12 families, with a misclassification rate of zero on the characterized kinomes of H. sapiens, M. musculus, D. melanogaster, C. elegans, S. cerevisiae, D. discoideum, and P. falciparum. The Library is shown to outperform BLASTP and a general Pfam hidden Markov model of the kinase catalytic domain in the retrieval and family‐level classification of protein kinases. The application of the Library to the 38 unclassified kinases of yeast enriches the yeast kinome in protein kinases of the families AGC (5), CAMK (17), CMGC (4), and STE (1), thereby raising the family‐level classification of yeast conventional protein kinases from 66.96 to 90.43%. The application of the Library to 21 eukaryotic genomes shows seven families (AGC, CAMK, CK1, CMGC, STE, PIKK, and RIO) to be present in all genomes analyzed, and so is likely to be essential to eukaryotes. Putative tyrosine kinases (TKs) are found in the plants A. thaliana (2), O. sativa ssp. Indica (6), and O. sativa ssp. Japonica (7), and in the amoeba E. histolytica (7). To our knowledge, TKs have not been predicted in plants before. This also suggests that a primitive set of TKs might have predated the radiation of eukaryotes. Putative tyrosine kinase‐like kinases (TKLs) are found in the fungi C. neoformans (2), P. chrysosporium (4), in the Apicomplexans C. hominis (4), P. yoelii (4), and P. falciparum (6), the amoeba E. histolytica (109), and the alga T. pseudonana (6). TKLs are found to be abundant in plants (776 in A. thaliana, 1010 in O. sativa ssp. Indica, and 969 in O. sativa ssp. Japonica). TKLs might have predated the radiation of eukaryotes too and have been lost secondarily from some fungi. The application of the Library facilitates the annotation of kinomes and has provided novel insights on the early evolution and subsequent adaptations of the various protein kinase families in eukaryotes. Proteins 2007. © 2007 Wiley‐Liss, Inc.
NAD+‐dependent DNA ligase (Rv3014c) from Mycobacterium tuberculosis: Novel structure‐function relationship and identification of a specific inhibitor
Authors: Srivastava Sandeep Kumar , Dube Divya , Kukshal Vandana , Jha Ashok Kumar , Hajela Kanchan , Ramachandran Ravishankar
Published: June 2007

Mycobacterium tuberculosis codes for an essential NAD+‐dependent DNA ligase (MtuLigA) which is a novel, validated, and attractive drug target. We created mutants of the enzyme by systematically deleting domains from the C‐terminal end of the enzyme to probe for their functional roles in the DNA nick joining reaction. Deletion of just the BRCT domain from MtuLigA resulted in total loss of activity in in vitro assays. However, the mutant could form an AMP‐ligase intermediate that suggests that the defects caused by deletion of the BRCT domain occur primarily at steps after enzyme adenylation. Furthermore, genetic complementation experiments using a LigA deficient E. coli strain demonstrates that the BRCT domain of MtuLigA is necessary for bacterial survival in contrast to E. coli and T. filiformis LigA, respectively. We also report the identification, through virtual screening, of a novel N‐substituted tetracyclic indole that competes with NAD+ and inhibits the enzyme with IC50 in the low μM range. It exhibits ∼15‐fold better affinity for MtuLigA compared to human DNA ligase I. In vivo assays using LigA deficient S. typhimurium and E. coli strains suggest that the observed antibacterial activity of the inhibitor arises from specific inhibition of LigA over ATP ligases in the bacteria. In silico ligand‐docking studies suggest that the exquisite specificity of the inhibitor arises on account of its mimicking the interactions of NAD+ with MtuLigA. An analysis of conserved water in the binding site of the enzyme suggests strategies for synthesis of improved inhibitors with better specificity and potency. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Solid‐phase peptide synthesis using nanoparticulate amino acids in water
Authors: Hojo Keiko , Ichikawa Hideki , Maeda Mitsuko , Kida Shinya , Fukumori Yoshinobu , Kawasaki Koichi
Published: June 2007

Solid‐phase peptide synthesis has many advantages compared with solution peptide synthesis. However, this procedure requires a large amount of organic solvents. Since safe organic solvent waste disposal is an important environmental problem, a technology based on coupling reaction of suspended nanoparticle reactants in water was studied. Fmoc‐amino acids are used widely, but most of them show low solubility in water. We prepared well‐dispersible Fmoc‐amino acid nanoparticles in water by pulverization using a planetary ball mill in the presence of poly(ethylene glycol). Leu‐enkephalin amide was prepared successfully using the nanoparticulate Fmoc‐amino acid on a poly(ethylene glycol)‐grafted Rink amide resin in water. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Strong Vector Minimization and Duality
Authors: Craven B. D.
Published: June 2007

A constrained minimum of a vector valued function is defined, in terms of an ordering cone. The definition chosen leads to a vector analog of the Kuhn‐Tucker theorem, and to a duality theorem where the dual problem has a vector valued objective function, and weak duality is defined by appropriate cone orderings. Also proved are a vector valued converse duality theorem, and a vector quasiduality theorem which does not require convexity. The results are related to perturbations of the objective function in a minimization problem.
Rayleigh‐Taylor Instability of a Visco‐Elastic Fluid
Authors: Ariel P. D. , Aggarwala B. D.
Published: June 2007

The character of equilibrium of an incompressible visco‐elastic fluid of variable density stratified in the vertical direction has been investigated. It is demonstrated that the solution is characterized by a variational principle. Use has been made of this principle to obtain approximate solution for an Oldroyd fluid of exponentially varying density confined between two horizontal boundaries. It is shown that the rate at which the system departs from equilibrium increases with the stress relaxation time and decreases as the strain retardation time increases. For a configuration in which gravity effects are ignored, it is found that the waves can be excited for some disturbances for which no oscillatory motion is possible in a newtonian fluid. The effects of rotation are also considered. Finally the usefulness of variational principle is checked by comparing some exact results with approximate ones.
Variational Principles for Rate Boundary‐Value Problems in Non‐Associated Plasticity
Authors: Telega J. J.
Published: June 2007

This study concerns a systematic search for variational principles applicable in solving rate boundary‐value problems of nonassociated plasticity. An investigated solid is assumed to be elastic‐plastic, work hardening and/or softening, obeying non‐associated flow rule. Coupling between elastic and plastic deformation has also been included. It is shown by means of the method of adding the adjoint operator that the counterparts of the variational principles of H u ‐ Washizu and Hellinger‐Reissner can be derived. Variational principles corresponding to the principles of a stationary value of potential energy and stationary value of complementary energy are studied. Convenient in applications counterparts of the principles of virtual velocities, virtual changes of rate of stresses and virtual work are derived. Two reciprocal theorems are formulated.
Solution of Einstein's Gravitational Field Equations by the Finite Element Method
Authors: Gass N.
Published: June 2007

Einstein's field equations of gravitation in presence of matter are presented in the form of a discrete functional from which, after performing an extremization process, a system of nonlinear algebraic equations arises. On this basis, a 4‐dimensional finite element is developed and in the case of spherical symmetry and time‐independence, a numerical example is carried out.
Unsteady Boundary Layer on a Two Dimensional or Axisymmetric Body with Higher Order Effects
Authors: Arunachalam M. , Rajappa N. R.
Published: June 2007

An analysis of the higher order effects upon the boundary layer growth on two dimensional and axisymmetric bodies which move impulsively with a linear velocity as an exponential function of time, is presented. Using the method of matched asymptotic expansions the full Navier‐Stokes equations are solved analytically for the universal velocity profiles. The theory is applied to study the motion of cylinder in two dimensions and sphere in three dimensions.
On the MHD‐Instability of Slowly Spreading Jets
Authors: Plaschko P.
Published: June 2007

The problem of inviscid instability of electrically conducting, slowly diverging circular jets in the presence of homogeneous axial magnetic fields is analyzed. Using the method of multiple scales, the study investigates the spatial growth of axisymmetric disturbances in the limit of very low values of the magnetic Reynolds number. It is shown that the effect of the combined action of jet divergence and magnetic field is to pick out disturbances suffering the greatest axial gain. The corresponding Strouhal numbers are reduced by the impact of the field as well as the gains and the regime where the growth can take place.
Some New RKT‐Formulas for First‐Order Differential Equations Requiring a Minimum Number of Differentiations
Authors: Fehlberg E.
Published: June 2007

For first‐order differential equations, new RKT (Runge‐Kutta‐Transformation)‐formulas with stepsize control are derived. Formulas of the 9th, 11th, and 13 th order are presented requiring a minimum number of differentiations of the differential equations. Their coefficients are tabulated in fraction form. The application of the formulas to quadrature problems is discussed in an appendix.