bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of optimal number of projections and parametric sensitivity analysis of operators for parallel‐ray transmission tomography using hybrid continuous genetic algorithm
Authors: Qureshi Shahzad Ahmad , Mirza Sikander M. , Arif M.
Published: June 2007

In this work, a hybrid continuous genetic algorithm (HCGA) based methodology has been developed for optimization of number of projections for parallel‐ray transmission tomography. The HCGA calculations with filtered back‐projection (FBP) utilize 8 bits for both head and lung phantoms. The effect of selection operator through proportionate, truncation, and tournament schemes has been analyzed along with the introduction of a mixed‐selection scheme. Image quality has been measured using root‐mean‐squared error, Euclidean error and peak signal‐to‐noise ratios. The sensitivity of reconstructed image quality on various mutation operators, namely standard, gradient‐, and offset‐based schemes, has been analyzed along with the effect of number of projections. The number of projections has resulted in maximization of image quality while minimizing the radiation hazard involved. The results of HCGA have been compared with FBP as a deterministic technique and simulated annealing (SA) as a stochastic technique for IRT approximation. For the 8 × 8 head and lung phantoms, HCGA, SA, FBP, have resulted PSNR values correspondingly as 40.47, 33.92, 8.28 and 26.38, 20.36, 12.98 dB. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 10–21, 2007
In vivo bone response to 3D periodic hydroxyapatite scaffolds assembled by direct ink writing
Authors: Simon Joshua L. , Michna Sarah , Lewis Jennifer A. , Rekow E. Dianne , Thompson Van P. , Smay James E. , Yampolsky Andrew , Parsons J. Russell , Ricci John L.
Published: June 2007

The in vivo bone response of 3D periodic hydroxyapatite (HA) scaffolds is investigated. Two groups of HA scaffolds (11 mm diameter × 3.5 mm thick) are fabricated by direct‐write assembly of a concentrated HA ink. The scaffolds consist of cylindrical rods periodically arranged into four quadrants with varying separation distances between rods. In the first group, HA rods (250 μm in diameter) are patterned to create pore channels, whose areal dimensions are 250 × 250 μm2 in quadrant 1, 250 × 500 μm2 in quadrants 2 and 4, and 500 × 500 μm2 in quadrant 3. In the second group, HA rods (400 μm in diameter) are patterned to create pore channels, whose areal dimensions of 500 × 500 μm2 in quadrant 1, 500 × 750 μm2 in quadrants 2 and 4, and 750 × 750 μm2 in quadrant 3. Each group of scaffolds is partially densified by sintering at 1200°C prior to being implanted bilaterally in trephine defects of skeletally mature New Zealand White rabbits. Their tissue response is evaluated at 8 and 16 weeks using micro‐computed tomography, histology, and scanning electron microscopy. New trabecular bone is conducted rapidly and efficiently across substantial distances within these patterned 3D HA scaffolds. Our observations suggest that HA rods are first coated with a layer of new bone followed by subsequent scaffold infilling via outward and inward radial growth of the coated regions. Direct‐write assembly of 3D periodic scaffolds composed of micro‐porous HA rods arrayed to produce macro‐pores that are size‐matched to trabecular bone may represent an optimal strategy for bone repair and replacement structures. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA
Authors: San Juan Aurélie , Ducrocq Grégory , Hlawaty Hanna , Bataille Isabelle , Guénin Erwann , Letourneur Didier , Feldman Laurent J.
Published: June 2007

In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid‐base titration, size exclusion chromatography, Fourier‐transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
The response of osteoblast‐like cells towards collagen type I coating immobilized by p‐nitrophenylchloroformate to titanium
Authors: van den Dolder Juliette , Jansen John A.
Published: June 2007

The scaffold surface composition can be altered by the use of surface coatings. The use of thin coatings will give special surface properties, while the bulk properties of the scaffold are preserved. Collagen type I is known to play an important role during cell adhesion as well as osteoblast differentiation. A common way to coat surfaces is the adsorption method. An alternative way is the use of a protein immobilization method like p‐nitrophenyl chloroformate. In this study, we investigated the effect of a collagen type I coating and p‐nitrophenyl chloroformate as a protein immobilization method on osteoblast adhesion, proliferation, and differentiation. Titanium fiber meshes were treated with sodium hydroxide (NaOH), followed by p‐nitrophenyl chloroformate, and coated with collagen type I. Osteoblast‐like cells were seeded into the meshes and cultured for 24 days. The cell attachment, proliferation, and differentiation were measured by using Live and Dead assay, cell counting, DNA analysis, alkaline phosphatase activity assay, calcium content measurement, Real Time PCR (QPCR), and scanning electron microscopy (SEM). Results demonstrated that initially less cells were attached to the covalently bounded collagen meshes (NPC‐Col) compared with titanium as control (Ti) and adsorbed collagen meshes (ABS‐Col). Further, a decreased growth curve of cells cultured on the NPC‐Col meshes was observed in comparison with Ti and ABS‐Col meshes. The calcium measurements and SEM pictures revealed that all three surfaces showed differentiation of osteoblast‐like cells after 8–24 days. On the basis of our results, we conclude that initially less cells were attached to the NPC‐Col meshes and that they had a decreased proliferation rate. Further, we conclude that an adsorbed collagen type I coating stimulated the osteoblastic differentiation of rat bone marrow cells. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Antimicrobial polyethylene with controlled copper release
Authors: Zhang Wei , Zhang Yihe , Ji Junhui , Yan Qing , Huang Anping , Chu Paul K.
Published: June 2007

Good antiinfection properties of medical polymers, especially those used in artificial organs, are crucial to the minimization of microbial attack in nosocomial treatments. However, medical polymers fabricated by conventional methods usually have unstable and short‐lived antimicrobial effects because of unsteady out‐diffusion of the antibacterial species from the organic matrix. Here, we introduce a dual plasma implantation process to enhance the properties. An inorganic antibacterial element, copper, is introduced into a medical polymer, polyethylene (PE), by means of copper plasma immersion ion implantation (PIII) and a subsequent nitrogen PIII process is used to regulate the release of the implanted Cu. X‐ray photoelectron spectroscopy and transmission electron microscopy reveal that a relatively large amount of copper of about 11% is implanted into PE to a depth of several hundred nanometers. Chemical analyses confirm that the implanted Cu does not bond with the polymer matrix. However, the N2 plasma treatment produces various functional bonds such as CN, and CN which exert appreciable influence on regulating the out‐diffusion rate of copper. The large amount of embedded Cu, coupled with controlled release of the element to the surface, gives rise to excellent and long‐lasting surface antibacterial properties of the plasma‐treated polymer. The capability of controlling the release and storing the antibacterial reagent in a buried layer leads to better antimicrobial polymeric materials for medicine. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Sensate scaffolds coupled to telemetry can monitor in vivo loading from within a joint over extended periods of time
Authors: Geffre Chris P. , Bliss Cody L. , Szivek John A. , DeYoung Donald W. , Ruth John T. , Margolis David S.
Published: June 2007

Polymer scaffolds have been used as a tool to provide growth and integration of engineered tissue substrates to repair damaged tissues in many organ systems including articular cartilage. Previous work has shown that “sensate” scaffolds, with integrated strain gauges have the potential for use as both a delivery vehicle for engineered cartilage as well as a device that can measure real time, in vivo joint loading. The purpose of this study was to use an implanted subminiature telemetry system to collect in vivo joint loading measurements over an extended period following placement of a “sensate” scaffold. Measurements were collected from seven of nine sensors that were implanted into the stifles of three canines. The limb loading rates and load distribution through gait were dependent on stride time but did not vary with time post op. The peak loads were not dependent on stride time but significantly increased with time post op. This demonstrated that peak loading measured with “sensate” scaffolds can be used to monitor healing. The portability of the “sensate” scaffolds coupled to telemetry systems highlights the potential use of this system in a clinical research setting to gather important information to improve tissue engineering and rehabilitation regimens. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Induction of Id2 expression by cardiac transcription factors GATA4 and Nkx2.5
Authors: Lim Joong‐Yeon , Kim Won Ho , Kim Joon , Park Sang Ick
Published: June 2007

Inhibitor of differentiation/DNA binding (Id) proteins function as a regulator of helix‐loop‐helix proteins participating in cell lineage commitment and differentiation. Here, we observed a marked induction of Id2 during cardiomyocyte differentiation from P19CL6 murine embryonic teratocarcinoma stem cells, prompting us to investigate the upstream regulatory mechanism of Id2 induction. Computer analysis of Id2 promoter and subsequent electrophoretic mobility shift assay revealed several binding sites for GATA4 and Nkx2.5 within the Id2 promoter. By further deletion and mutation analysis of the respective binding site, we identified that two motifs located at −497/−502 and −264/−270 were functionally important for Id2 promoter activation by GATA4 and Nkx2.5, respectively. Overexpression of GATA4 and/or Nkx2.5 induced not only Id2 promoter activity but also Id2 protein expression. Additionally, Id proteins significantly inhibit the GATA4 and Nkx2.5‐dependent transcription, suggesting Id proteins may play a regulatory role in cardiogenesis. Collectively, our results demonstrate that GATA4 and Nkx2.5 could be one of the upstream regulators of Id2. J. Cell. Biochem. 103: 182–194, 2008. © 2007 Wiley‐Liss, Inc.
Liver regeneration
Authors: Michalopoulos George K.
Published: June 2007

Liver regeneration after partial hepatectomy is a very complex and well‐orchestrated phenomenon. It is carried out by the participation of all mature liver cell types. The process is associated with signaling cascades involving growth factors, cytokines, matrix remodeling, and several feedbacks of stimulation and inhibition of growth related signals. Liver manages to restore any lost mass and adjust its size to that of the organism, while at the same time providing full support for body homeostasis during the entire regenerative process. In situations when hepatocytes or biliary cells are blocked from regeneration, these cell types can function as facultative stem cells for each other. J. Cell. Physiol. 213: 286–300, 2007. © 2007 Wiley‐Liss, Inc.
Circular‐arc digraphs: A characterization
Authors: Sen M. , Das S. , West Douglas B.
Published: June 2007

Given a family F of ordered pairs of sets {(Su,Tu): u ϵ V}, the intersection digraph of F is the digraph with vertices V defined by uv ϵ E(D) if Su ≠ Tv Ø. Interval digraphs are intersection digraphs of families in which every set is an interval, and were characterized in a previous paper by conditions on the adjacency matrix. In this paper, another such condition leads to an adjacency matrix characterization of circular‐arc digraphs, the intersection digraphs of families in which every set is an arc of a circle.
Domination in colored complete graphs
Authors: Erdös P. , Faudree R. , Gyárfás A. , Schelp R. H.
Published: June 2007

We prove the following conjecture of Erdös and Hajnal: For any fixed positive integer t and for any 2‐coloring of the edges of kn, there exists X ⊂ v(KN) such that |≦| and X monochromatically dominates all but at most n/2t vertices of Kn. In fact, X can be constructed by a fast greedy algorithm.
Regular graphs having the same path layer matrix
Authors: Dobrynin A. A.
Published: June 2007

The path layer matrix (or path degree sequence) of a graph G contains quantitative information about all paths in G. Elements (i,j) in this matrix is the number of simple paths in G having initial vertex v, and length j. For every r ≥ 3, pairs of nonisomorphic r‐regular graphs having the same path layer matrix are presented.
Certain graph invariants do not distinguish all graphs
Authors: Chalcraft D. A.
Published: June 2007

This paper considers a certain fairly large class of graph invariants and shows that for any invariant in this class, there is a pair of nonisomorphic graphs that have the same invariant. Some explicit examples of such invariants are discussed.
Hamilton cycles and closed trails in iterated line graphs
Authors: Catlin Paul A. , Janakiraman Iqbalunnisa T. N. , Srinivasan N.
Published: June 2007

Let G be an undirected connected graph that is not a path. We define h(G) (respectively, s(G)) to be the least integer m such that the iterated line graph Lm(G) has a Hamiltonian cycle (respectively, a spanning closed trail). To obtain upper bounds on h(G) and s(G), we characterize the least integer m such that Lm(G) has a connected subgraph H, in which each edge of H is in a 3‐cycle and V(H) contains all vertices of degree not 2 in Lm(G). We characterize the graphs G such that h(G) — 1 (respectively, s(G)) is greater than the radius of G.
Bounds for the crossing number of the N‐cube
Authors: Madej Tom
Published: June 2007

Let Qn denote the n‐dimensional hypercube. In this paper we derive upper and lower bounds for the crossing number v(Qn), i.e., the minimum number of edge‐crossings in any planar drawing of Qn. The upper bound is close to a result conjectured by Eggleton and Guy and the lower bound is a significant improvement over what was previously known. Let N = 2n be the number of vertices of Qn. We show that v(Qn) < 1/6N2. For the lower bound we prove that v(Qn) = Ω(N(lg N)c lg lg N), where c > 0 is a constant and lg is the logarithm base 2. The best lower bound using standard arguments is v(Qn) = Ω(N(lg N)2). The lower bound is obtained by constructing a large family of homeomorphs of a subcube with the property that no given pair of edges can appear in more than a constant number of the homeomorphs.
Improved lower bounds on k‐independence
Authors: Caro Yair , Tuza Zsolt
Published: June 2007

A vertex set Y in a (hyper)graph is called k‐independent if in the sub(hyper)‐graph induced by Y every vertex is incident to less than k edges. We prove a lower bound for the maximum cardinality of a k‐independent set—in terms of degree sequences—which strengthens and generalizes several previously known results, including Turán's theorem.
Local extrema in genus‐stratified graphs
Authors: Gross Jonathan L. , Rieper Robert G.
Published: June 2007

Beyond the obvious organization of all the orientable imbeddings of a graph according to the genus of the imbedding surface, there are several seemingly natural ways to ascribe proximity of imbeddings. One of these is to stipulate that two imbeddings are adjacent if one imbedding can be obtained from the other by moving one end of an edge in its rotation. If one associates “altitude” with genus, then one might hope to construct algorithms for minimum genus and maximum genus by descent and ascent, respectively. This investigation of the structure of the system of orientable graph imbeddings reveals that although there may occur arbitrarily deep traps among the local minima, there cannot exist any strict local maxima. These new discoveries seem consistent with a known contrast in the computational complexity of the maximum genus and minimum genus problems. That is, whereas Furst, Gross, and McGeoch have devised a polynomial‐time algorithm to find the maximum genus of an arbitrary graph, Thomassen has proved that the problem of finding the minimum genus is NP‐complete.
Bounding the number of embeddings of 5‐connected projective‐planar graphs
Authors: Kitakubo Shigeru
Published: June 2007

A graph is said to be projective‐planar if it is nonplanar and is embeddable in a projective plane. In this paper we show that the numbers of projectiveplanar embeddings (up to equivalence) of all 5‐connected graphs have an upper bound c(⩽120).
The structure and maximum number of maximum independent sets in trees
Authors: Zito Jennifer
Published: June 2007

A subset of vertices is a maximum independent set if no two of the vertices are joined by an edge and the subset has maximum cardinality. in this paper we answer a question posed by Herb Wilf. We show that the greatest number of maximum independent sets for a tree of n vertices is

magnified image

We give the families of trees on which these maxima are achieved.

Proving which trees are extremal depends upon the structure of maximum independent sets in trees. This structure is described in terms of adjacency rules between three types of vertices, those which are in all, no, or some maximum independent sets. We show that vertices that are in some but not all maximum independent sets of the tree are joined in pairs by the α‐critical edges (edges whose removal increases the size of a maximum independent set). The number of maximum independent sets is shown to depend on the structure within the tree of the α‐critical edges.
On the structure of unbreakable graphs
Authors: Olariu Stephan
Published: June 2007

A nonempty set C of vertices is a star‐cutset in a graph G if G – C is disconnected and some vertex in C is adjacent to all the remaining vertices in C. Vašek Chvátal proposed to call a graph G unbreakable if neither G nor its complement G has a star‐cutset. A path with four vertices and three edges will be termed a P4. An edge uv of a graph G is called a wing, if for some vertices x, y, {u,v,x,y} induces a P4 in G. We define recursively the coercion class Cuv of a wing uv as follows:

uv ∈ Cuv, and

if xy ∈ Cuv and xy, x'y' are wings of a same P4 in G, then x'y' ∈ Cuv.

The purpose of this work is to present new results concerning unbreakable graphs, using the notion of coercion class. These results include a theorem asserting that every unbreakable graph contains at most two distinct coercion classes and a structure theorem for those unbreakable graphs that contain precisely two coercion classes. These results generalize several previously known results about unbreakable graphs.
Do 3n − 5 edges force a subdivision of K5?
Authors: Kézdy André E. , McGuinness Patrick J.
Published: June 2007

A conjecture of Dirac states that every simple graph with n vertices and 3n − 5 edges must contain a subdivision of K5. We prove that a topologically minimal counterexample is 5‐connected, and that no minor‐minimal counterexample contains K4 – e. Consequently, Dirac's conjecture holds for all graphs that can be embedded in a surface with Euler characteristic at least − 2.
20‐relative neighborhood graphs are hamiltonian
Authors: Chang M. S. , Tang C. Y. , Lee R. C. T.
Published: June 2007

For any two points p and q in the Euclidean plane, define LUNpq = {v|v ∈ R2, dpv < dpq and dqv < dpq}, where duv is the Euclidean distance between two points u and v. Given a set of points V in the plane, let LUNpq(V) = V ∩ LUNpq. Toussaint defined the relative neighborhood graph of V, denoted by RNG(V) or simply RNG, to be the undirected graph with vertices V such that for each pair p,q ∈ V, (p,q) is an edge of RNG(V) if and only if LUNpq (V) = ϕ. The relative neighborhood graph has several applications in pattern recognition that have been studied by Toussaint. We shall generalize the idea of RNG to define the k‐relative neighborhood graph of V, denoted by kRNG(V) or simply kRNG, to be the undirected graph with vertices V such that for each pair p,q ∈ V, (p,q) is an edge of kRNG(V) if and only if | LUNpq(V) | < k, for some fixed positive number k. It can be shown that the number of edges of a kRNG is less than O(kn). Also, a kRNG can be constructed in O(kn2) time. Let Ec = {epq| p ∈ V and q ∈ V}. Then Gc = (V,Ec) is a complete graph. For any subset F of Ec, define the maximum distance of F as maxepq∈Fdpq. A Euclidean bottleneck Hamiltonian cycle is a Hamiltonian cycle in graph Gc whose maximum distance is the minimum among all Hamiltonian cycles in graph Gc. We shall prove that there exists a Euclidean bottleneck Hamiltonian cycle which is a subgraph of 20RNG(V). Hence, 20RNGs are Hamiltonian.
Vertex‐switching, isomorphism, and pseudosimilarity
Authors: Ellingham M. N.
Published: June 2007

A vertex‐switching Gs of a graph G is obtained by deleting from G all edges of G with exactly one end in the set of vertices S, and then adding to G all edges of the complement of G with exactly one end in S. We characterize the situations in which Gs is isomorphic to G, a result with application to the vertex‐switching reconstruction problem. We use these results to construct pairs of vertex‐switching pseudosimilar vertices, nonsimilar vertices u and v in a graph G with G{u} isomorphic to G{v}. We show that every such pair can be constructed by our methods.
Some extremal results in cochromatic and dichromatic theory
Authors: Erdös Paul , Gimbel John , Kratsch Dieter
Published: June 2007

For a graph G, the cochromatic number of G, denoted z(G), is the least m for which there is a partition of the vertex set of G having order m. where each part induces a complete or empty graph.

We show that if {Gn} is a family of graphs where Gn has o(n2 log2(n)) edges, then z(Gn) = o(n). We turn our attention to dichromatic numbers. Given a digraph D, the dichromatic number of D is the minimum number of parts the vertex set of D must be partitioned into so that each part induces an acyclic digraph. Given an (undirected) graph G, the dichromatic number of G, denoted d(G), is the maximum dichromatic number of all orientations of G. Let m be an integer; by d(m) we mean the minimum size of all graphs G where d(G) = m. We show that d(m) = θ(m2 ln2(m)).
Expected numbers at hitting times
Authors: McDiarmid Colin
Published: June 2007

We determine exactly the expected number of hamilton cycles in the random graph obtained by starting with n isolated vertices and adding edges at random until each vertex degree is at least two. This complements recent work of Cooper and Frieze. There are similar results concerning expected numbers, for example, of perfect matchings, spanning trees, hamilton paths, and directed hamilton cycles.
Cycle covers of graphs with a nowhere‐zero 4‐flow
Authors: Raspaud André
Published: June 2007

It is shown that the edges of a simple graph with a nowhere‐zero 4‐flow can be covered with cycles such that the sum of the lengths of the cycles is at most |E(G)| + |V(G)| −3. This solves a conjecture proposed by G. Fan.
Self‐complementary symmetric graphs
Authors: Zhang Hong
Published: June 2007

The class of self‐complementary symmetric graphs is characterized using the classification of finite simple group.
On ramsey‐tuŕan numbers for 3‐graphs
Authors: Sidorenko A. F.
Published: June 2007

For every r‐graph G let π(G) be the minimal real number ϵ such that for every ϵ < 0 and n ϵ n0(λ, G) every R‐graph H with n vertices and more than (π + ϵ)(nr) edges contains a copy of G. The real number λ(G) is defined in the same way, adding the constraint that all independent sets of vertices in H have size 0(n). Erdös and Sós asked whether there exist r‐graphs G with π(G) < λ(G) < 0. Frankl and Rödl proved that there exist infinitely many such r‐graphs for every r ≦ 3. However, no example of an r‐graph with above property was known. We construct an example of such a 3‐graph with 7 vertices and 9 edges.
A short proof of a theorem of dirac's about hadwiger's conjecture
Authors: Woodall D. R.
Published: June 2007

A Short proof is given of the theorem that every grph that does not have K4 as a subcontraction is properly vertex 3‐colorable.
On zero‐trees
Authors: Füredi Zoltán , Kleitman D. J.
Published: June 2007

Consider an integer‐valued function on the edge‐set of the complete graph Km+1. The weight of an edge‐subset is defined to be the sum of the associated weights. It is proved that there exists a spanning tree with weight 0 modulo m.
Projective‐planar graphs with even duals
Authors: Negami Seiya
Published: June 2007

Let G be a connected graph which is projective‐planar but is not planar. It will be shown that G can be embedded in the projective plane so that it has only even faces if and only if either G is bipartite or its canonical bipartite covering is planar and that such an embedding is unique if G is 3‐connected.
Characterizing vertex‐transitive pq‐graphs with an imprimitive automorphism subgroup
Authors: Marušič Dragan , Scapellato Raffaele
Published: June 2007

Vertex‐transitive graphs with pq vertices, where p and q are primes, having an imprimitive subgroup of automorphisms, are characterized. © 1992 John Wiley & Sons, Inc.
A characterization of Hamiltonian prisms
Authors: Paulraja P.
Published: June 2007

A characterization is established for a graph G to have a Hamilton cycle in G × K2, the prism over G. Moreover, it is shown that every 3‐connected graph has a 2‐connected spanning bipartite subgraph. Using this result, the existence of a Hamilton cycle in the prism over every 3‐connected cubic graph is established. Further, the existence of a Hamilton cycle in the prism over a cubic 2‐connected graph is also discussed. Earlier results in this direction are shown to be particular cases of the results obtained here. © 1993 John Wiley & Sons, Inc.
Constraints on the number of maximal independent sets in 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. Let i(G) denote the number of maximal independent sets of G. Here, we prove two conjectures, suggested by P. Erdös, that the maximum number of maximal independent sets among all graphs of order n in a family Φ is o(3n/3) if Φ is either a family of connected graphs such that the largest value of maximum degrees among all graphs of order n in Φ is o(n) or a family of graphs such that the approaches infinity as n → ∞.
Connectivity properties of locally semicomplete digraphs
Authors: Guo Yubao , Volkmann Lutz
Published: June 2007

It is shown that every k‐connected locally semicomplete digraph D with minimum outdegree at least 2k and minimum indegree at least 2k − 2 has at least m = max{2, k} vertices x1, x2, ⃛, xm such that D − xi is k‐connected for i = 1, 2, ⃛, m.
The w‐median of a connected strongly chordal graph
Authors: Lee Hai‐Yen , Chang Gerard J.
Published: June 2007

Suppose G = (V, E) is a graph in which every vertex x has a non‐negative real number w(x) as its weight. The w‐distance sum of a vertex y is DG, w(y) = σx≅v d(y, x)w(x). The w‐median of G is the set of all vertices y with minimum w‐distance sum DG,w(y). This paper shows that the w‐median of a connected strongly chordal graph G is a clique when w(x) is positive for all vertices x in G.
Covering vertices by cycles
Authors: Kouider Mekkia
Published: June 2007

“If G is a 2‐connected graph with n vertices and minimum degree d, then the vertices of G can be covered by less than n/d cycles. This settles a conjecture of Enomoto, Kaneko and Tuza for 2‐connected graphs.”
Intermittent parathyroid hormone (PTH) treatment and age‐dependent effects on rat cancellous bone and mineral metabolism
Authors: Friedl Gerald , Turner Russell T. , Evans Glenda L. , Dobnig Harald
Published: June 2007

In recent years, intermittent PTH treatment has been investigated extensively for its efficacy in preventing osteoporotic fractures and to improve fracture healing and implant fixation. Although these tasks concern patients of all ages, very little is known about whether aging impacts the bone anabolic response to PTH. Female Sprague‐Dawley rats of 1, 3, and 13 months of age were either treated by hPTH‐(1‐34) or by vehicle solution (CTR) for 1 week. As main outcome measures, we determined the effects on static and dynamic histomorphometry of cancellous bone. In addition, we measured gene expression in femur and serum parameters reflecting bone turnover and mineral metabolism. There was a profound decrease in bone formation rate (BFR) with aging in CTR rats, whereas PTH treatment resulted in a significant relative 1.5‐, 3‐, and 4.7‐fold increase in BFR, without altering indices of bone resorption. Aging decreased and PTH increased mRNA levels for bone matrix proteins and growth factors in a gene‐specific manner. In younger animals, PTH‐induced a marked stimulation in the mineral apposition rate with no effect on osteoblast number, whereas the latter was increased in older animals (1.0‐, 1.7‐, and 3.1‐fold). Treatment with PTH in young rats led to a significant increase in trabecular number (1.6–2.6/mm, p < 0.05), whereas older rats demonstrated increases in trabecular thickness only (52.8–77.8 µm, p < 0.001). Although PTH increased bone formation at all ages, we found significant age‐related differences in the cellular and molecular mechanisms involved in the bone anabolic response to the hormone. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1454–1464, 2007
Laboratory preparation and evaluation of Pollock variety avocado (Persea americana Mill) guacamole
Authors: Ramtahal Giselle A , Akingbala John O , Baccus‐Taylor Gail SH
Published: June 2007

Guacamole was produced from ripe avocado (Persea americana) by blending the pulp with local herbs, spices and salt. The guacamole was stored at 5 °C for 2 weeks, during which physical, chemical and microbial analyses were conducted. Organoleptic evaluations by a semi‐trained panel were also performed, until the guacamole was deemed unfit for human consumption. The results indicated that fresh avocado pulp contains 835, 13, 16, 92, 44, 16 and 0.078 g kg−1, moisture, ash, protein, fat, carbohydrate, fiber, and vitamin C respectively, and has a pH of 6.7; compared with 838, 13, 16, 92, 44, 16, and 0.042 g kg−1, respectively, of the same nutrients in freshly prepared guacamole, which has a pH of 6.0. During storage, the moisture content, consistency, total soluble solids and total titratable acidity (as citric acid) of the guacamole increased, but the vitamin C content decreased. The color of the avocado pulp, which darkened during conversion into guacamole, darkened further as storage increased as evidenced by a decrease in the L, a and b values. Sensory evaluation revealed that the mean storage period (5 °C) for the guacamole was 6 days. Although the fresh avocado pulp, the freshly prepared guacamole, and the stored guacamole contained bacteria, yeasts and molds, the pathogens Staphylococcus aureus and Salmonella were absent. Copyright © 2007 Society of Chemical Industry
The next problem in city zoning
Authors: Sloan Francis P.
Published: June 2007

New York City is “zoned” and in a residential zone, for instance, it is unlawful hereafter to build a store or facory. But stores or factories that were there before the law was passed, have not yet been dealt with and constitue a complex problem of advanced city planning.
THE FATE OF THE FIVE‐CENT‐FARE. II THE NEW TRAMWAYS CONTRACT IN MONTREAL
Authors: Wilcox Delos F.
Published: June 2007

The first article under this title appeared in the November issue and others will follow every month hereafter, covering the situation in various American cities. Montreal's solution, calling for service‐at‐cost plus a bonus for good service, is novel and ingenious though legally hampered.
How a tammany district attorney used his office for his own ends
Authors: Mellen Chase
Published: June 2007

The last trumped‐up case against City Club witnesses has now been dismissed and they are safely beyond the reach of the district attorney's vengeance, completing the case and making it possible now for the first time to tell the whole story.
Community service, INC.
Authors: Candler Martha
Published: June 2007

The peace‐time successor of the War Camp Community Service is the new Community Service, a central bureau for installing autonomous local organizations in towns that want more wholesome and universal neighborliness in recreation.
City planning in flesh and blood
Authors: Williams Whiting
Published: June 2007

Among our large cities Cleveland easily ranks first in the enterprise and forethought with which it has attacked its humanitarian problems and taken care of its people. This article sketches its history along these lines.
Zoning in practice
Authors: Cheney Charles H.
Published: June 2007

This was considered the most valuable paper delivered at the recent Buffalo Conference on City planning. It represents the new, California viewpoint in some respects and advances ideas that are not, as yet at least, universally accepted, although received with entire respect by city planners.
Winnipeg tries proportional representation
Authors: Harkness D. B.
Published: June 2007

Proportional Representation was first used in Winnipeg at the recent election of members of the provincial legislature. It returned representative members where the two party system had broken down.
A review of city planning in the United States, 1920‐1921
Authors: Kimball Theodora
Published: June 2007

The annual review by miss Kimball reflects increasing activity in city planning and zoning. For example, more than thirty states now have laws relating to some phase of city planning.
A computational strategy for poroelastic problems with a time interface between coupled physics
Authors: Néron D. , Dureisseix D.
Published: June 2007

This paper deals with a computational strategy suitable for the simulation of multiphysics problems and based on the LArge Time INcrement (LATIN) method. One of the main issues in the design of advanced tools for the simulation of such problems is to take into account the different time and space scales that usually arise with the different physics. Here, we focus on using different time discretizations for each physics by introducing an interface with its own discretization. The proposed application concerns the simulation of a 2‐physics problem: the fluid–structure interaction in porous media. Copyright © 2007 John Wiley & Sons, Ltd.
Digital cementum luminance analysis (DCLA): a tool for the analysis of climatic and seasonal signals in dental cementum
Authors: Wall‐Scheffler C. M. , Foley R. A.
Published: June 2007

Cementum banding patterns have been used by archaeozoologists and wildlife managers for a number of decades to assess the season and age at death of mammalian populations. However, the observation and measurement of the nature of cementum banding, especially that of the final band, has proved to be difficult except under conditions of excellent preservation and advanced microscopy. The research presented here details a method for extracting luminance data from the banding patterns of cementum in order to quantify the optical properties of cementum tissue. By doing so, analysis of the relationship between cementum deposition and environmental variables is achieved. We present the results of a digital cementum luminance analysis (DCLA) on a sample of first molars from two species,Ovis aries, Soay andCapra ibex. The results indicate that significant relationships occur between seasonal temperature changes and cementum histology. Furthermore, we show that luminance values can be used to assess the geographical range of genetically similar populations. Our results demonstrate that the study of luminance is a vital tool for the quantitative study of dental cementum for both archaeological and ecological studies. Copyright © 2007 John Wiley & Sons, Ltd.
What do consultants do, anyway?
Authors: Jackson Stephanie
Published: June 2007

This article describes some of the different roles or functions a consultant may fill, and discusses some of their implications for both clients and consultants. The focus is on the differences between consultants as generalists vs. specialist, and between consultants as advisors to others vs. direct providers of products or services.
Ethical issues in consulting
Authors: Schwartz Lois
Published: June 2007

Should NSPI establish on Ethics Committee? What is ethics, what are the ethical issues that confront consultants and how do they presently deal with them? This article is based on a year long research effort to identify common ethical dilemmas that arise in consultant‐client relationships and the difficulties both parties have in resolving them.
Time‐course of change in [11C]carfentanil and [11C]raclopride binding potential after a nonpharmacological challenge
Authors: Scott David J. , Stohler Christian S. , Koeppe Robert A. , Zubieta Jon‐Kar
Published: June 2007

Positron Emission Tomography (PET) with appropriate radiotracers and quantification methods allows the detection of changes in endogenous neurotransmission by determine the reduction in the binding potential (BP) of receptors before and after experimental challenges. These have typically employed psychostimulants and PET with dopamine (DA) receptor radiotracers. However, reductions in BP persist far beyond the increases in the release of the endogenous neurotransmitter, an effect ascribed to receptor internalization and recycling, a possible confound in repeated studies. Here we examined the time‐course of changes in BP during a nonpharmacological challenge, moderate levels of sustained pain, shown to induce robust reductions in μ‐opioid and DA D2 BP, as measured with [11C]carfentanil and [11C]raclopride. It was hypothesized that, contrary to pharmacological probes, the use of a more “physiological” stimulus would not be associated with persistent changes in the BP measures. The pain challenge was associated with reductions in μ‐opioid receptor BP in several cortical and subcortical regions. These did not persist in a subsequent scan. Similar results were obtained for DA D2 receptor BP, where the pain challenge induced significant reductions in the caudate nucleus. These data demonstrate that changes in receptor BP induced by a nonpharmacological challenge did not persist into subsequent scans. They further suggest differences in the effect of pharmacological and nonpharmacological probes on PET BP measures. These may reflect varying levels of change in receptor affinity, receptor internalization, and recycling depending on the type of challenge employed. Synapse 61:707–714, 2007. © 2007 Wiley‐Liss, Inc.
A small dopamine permeability of storage vesicle membranes and end product inhibition of tyrosine hydroxylase are sufficient to explain changes occurring in dopamine synthesis and storage after inhibition of neuron firing
Authors: Wallace Lane J.
Published: June 2007

Computer simulations of dopamine (DA) regulation at a striatal varicosity were developed to determine basic principles that explain the pattern of changes in level of neurotransmitter and its rate of synthesis and metabolism when DA neuron firing is inhibited. The models suggest that DA synthesis is normally at a slower rate because of end‐product inhibition of tyrosine hydroxylase (TH) by cytosolic DA. The vast majority of DA in the cytosol arrives there via “recycling”—DA that was released during an exocytotic event is moved into the cytosol via the dopamine transporter (DAT). When neuronal firing is inhibited, the amount of cytosolic DA markedly decreases as there is no recycling. The rate of DA synthesis then increases because of the loss of end‐product inhibition of TH. The newly synthesized DA is stored in vesicles, thus increasing the total amount of DA in the vesicles. A small amount of DA is continually leaking out of vesicles, and the amount leaking out increases proportionally to the amount of DA in vesicles. When the amount of DA leaking out balances the amount being stored by the vesicular monoamine transporter, DA accumulates in the cytosol. The accumulating DA inhibits TH activity, and the system enters a steady state condition characterized by approximately double the normal amount of DA in vesicles and approximately normal rate of DA synthesis and metabolism. Synapse 61:715–723, 2007. © 2007 Wiley‐Liss, Inc.
Free Convection in a Trench with Radiative Wall Conditions
Authors: De Socio L. M. , Misici L.
Published: June 2007

Free convection is considered in a rectangular trench with an assigned temperature distribution at the bottom and radiative vertical walls. Following a domain perturbation technique, the problem reduces to the Stokes' equation. After proving the existence and uniqueness of the solution, from a functional point of view, the stream function is expressed in closed form via a bi‐harmonic series and the shape of the free surface is also given. An application follows in order to show the convergence characteristics of the solution and the flow structure.
Dynamic Behavior of Distensible Fluid Lines Carrying a Pulsating Incompressible Liquid
Authors: Bauer H. F. , Metten St. , Siekmann J.
Published: June 2007

An analysis of the propagation of pressure waves through a thin‐walled elastic tube, filled with a streaming incompressible fluid, is presented. The outer surface of the tube is assumed to be free. Axially symmetric solutions for the linearized equations governing the motion of the (viscous or nonviscous) fluid and the (elastic) solid are obtained. The motion of the tube wall is described by the Donnell shell equations. The solutions lead to a complicated transcendental dispersion equation relating wave number and frequency. This equation is studied by both analytical and numerical means in some detail.
Schwingungen unter gleichzeitiger zufälliger Zwangs‐ und Parametererregung
Authors: Schmidt G.
Published: June 2007

Schwingungen eines Systems mit einem Freiheitsgrad, kombinierter zufälliger Zwangs‐ und Parametererregung in Form eines Weißen Rauschens und Rückstell‐, Trägheits‐ und Dämpfungsnichtlinearitäten werden untersucht. Mit Hilfe der Theorie der Itǒgleichungen und einer iterativen Methode von Stratonovich, die die Methode der stochastischen Mittelung verallgemeinert, werden stationäre Lösungen der Fokker‐Planck‐Kolmogorov‐Gleichung für die Verteilungsdichte der Amplitude gefunden, die zu Ergebnissen über verschiedene Momente und die Wahrscheinlichkeit für das Überschreiten eines festen Amplitudenniveaus führen.
Ecoulement moléculaire libre autour d'un dièdre droit
Authors: Tiem Dang Hong
Published: June 2007

Die freie Molekularströmung an einem konkaven rechtwinkligen Keil wird systematisch untersucht. Die ungestörte Gasströmung wird maxwellisch und die Reflektion an der Grenzfläche wird als vollkommen diffus vorausgesetzt. Es werden analytische Ausdrücke für die makroskopischen Größen der Gasströmung erhalten und die nummerischen Ergebnisse werden in Form von Linien gleicher Dichte, gleicher Temperatur und von Stromlinien wiedergegeben.
Der Einfluß der Verformungen des Grundzustandes auf die Stabilität gerader Stäbe
Authors: Heinen A. , Eilering S.
Published: June 2007

In [7] wurde eine allgemein gültige Stabilitätstheorie für gerade, elastische Stäbe hergeleitet, mit der jeder beliebige (auch nichtlineare) Grundzustand auf seine Stabilität hin untersucht werden kann. In dieser Arbeit werden die in [7] angegebenen Stabilitätsgleichungen für ein Kipp‐ und ein Torsionsproblem exakt gelöst. Dabei wird in exemplarischer Weise der oft erhebliche Einfluß der Verformungen des Grundzustandes aufgezeigt.
On Numerical Solution Scheme for Thermoelastic Problems in Inhomogeneous Media by means of Boundary‐Volume Element
Authors: Tanaka Masataka , Tanaka Kikuaki
Published: June 2007

The paper is concerned with thermoelastic problems in which the material constants are prescribed as arbitrary, continuous and differentiable functions of spatial coordinates. The formulation is made in terms of Green's function which is available in the literature for homogeneous elastostatics. The governing equation is transformed into a set of integral equations in the inner domain and also on the boundary. The resulting integral equations are discretized by means of boundary elements as well as volume elements. The behavior of the problems is completely determined by solving simultaneously the system of linear equations thus obtained.
Untersuchung von Parameternichtlinearitäten bei Übersetzungsgetrieben
Authors: Hortel M. , Schmidt G.
Published: June 2007

An Hand eines elastisch gelagerten Zahnradübersetzungsgetriebes wird der Einfluß der nichtlinearen, mit der Zeit veränderlichen Steifigkeitsglieder, der sogenannten Parameternichtlinearität, untersucht. Die mit Hilfe der Integralgleichungsmethode durchgeführte Analyse des Hauptresonanzfalles zeigt insbesondere den beachtlichen qualitativen Einfluß der Parameternichtlinearität. Diese Eigenschaften können nicht nur beim Konstruktionsentwurf, sondern auch in manchen Fällen an fertigen Konstruktionen zu schwingungsverkleinernden Änderungen ausgenützt werden.
Angenäherte Fehlerermittlung Für Modalsynthese‐Ergebnisse innerhalb der Systemanalyse und Systemidentifikation
Authors: Natke H. G.
Published: June 2007

Die Modalsynthese ist ein Verfahren zur Untersuchung des dynamischen Verhaltens komplizierter schwingungsfähiger elastomechanischer Systeme mittels Subsystem‐Ergebnissen. In der vorliegenden Arbeit ist Für endlichdimensionale Systeme ein. Verfahren zur angenäherten Fehlerermittlung der Modalsyntheseergebnisse mitgeteilt, das auf der dynamischen Kondensation beruht und die Kenntnis der Modalgrößen der unterdrückten Freiheitsgrade nicht benötigt. Das Vorgehen ist bei jeder regulären Transformation in generalisierte Koordinaten anwendbar. Beispiele zeigen Für eine ungünstige Transformation die Güte der angenäherten Fehler.
The General Theory of the Motion of a Single Wheelset Moving through a Curve with Constant Radius and Cant
Authors: de Pater A. D.
Published: June 2007

Paper deals with the problem of the motion of a railway wheelset through a curve with constant radius and cant. The investigation includes both the stationary and the parasitic movement. General equations of motion are derived; both as Lagrange's equations and as the equations expressing the rate of change of the momentum and of the moment of momentum of the wheelset. For values of the curve radius which tend to infinity, the equations of motion can be considered as exact‐ones. The equations are very complicated and before solving them they should be reduced by taking into account that the wheelset and contact point displacements always remain small as compared with the track gauge, whereas the rotation angles (of the parasitic motion) of the wheelset remain small with respect to unity. The draft of such a first‐order theory will be the subject of a forthcoming publication.