bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct dynamics study on the reaction of acetaldehyde with ozone
Authors: Yang Jing , Li Qian Shu , Zhang Shaowen 
Published: June 2007

AbstractThe hydrogen abstraction reaction of ozone with acetaldehyde has been studied theoretically over the temperature range 250–2500 K. Two different reactive sites of acetaldehyde molecule, CH3 and CHO groups have been investigated, and results confirm that the CHO group is a highly reactive site. In this study, the geometries and harmonic vibrational frequencies of all stationary points are calculated at the MPW1K, BHandHLYP, and MPWB1K levels of theory. The minimum energy paths (MEPs) were obtained at the MPW1K/6‐31+G(d,p) level of theory. To refine the energies along the MEPs of each channel, single‐point energy calculations were performed by a higher‐level energy calculation method (denoted as HL). The rate constants were evaluated based on the MEPs from the HL method in the temperature range 250–2500 K by using the conventional transition state theory (TST), the canonical variational transition state theory (CVT), the microcanonical variational transition state theory (μVT), the CVT coupled with small‐curvature tunneling (SCT) correction (CVT/SCT), and the μVT coupled with Eckart tunneling correction (μVT/Eckart). The fitted three‐parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CHO group are kCVT/SCT(T) = 4.92 × 10−27·T3.77·e(−7867.0/T) and kμVT/Eckart(T) = 2.10 × 10−27·T3.90·e(−7706.2/T), respectively. The fitted three‐parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CH3 group are kCVT/SCT(T) = 1.27 × 10−27·T3.94·e(−14554.1/T) and kμVT/Eckart(T) = 1.62 × 10−26·T3.66·e(−15459.8/T), respectively. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Ang II and EGF synergistically induce COX‐2 expression via CREB in intestinal epithelial cells
Authors: Pham Hung , Chong Benny , Vincenti Romina , Slice Lee W. 
Published: June 2007

AbstractCyclooxygenase (COX)‐2 derived prostaglandins (PGs) play a major role in intestinal inflammation and colorectal carcinogenesis. Because COX‐2 is the rate‐limiting step in the production of PGs, mechanisms that regulate COX‐2 expression control PG production in the cell. Using the non‐tumorigenic, rat intestinal epithelial cell, IEC‐18, we demonstrate that co‐activation of endogenously expressed AT1 receptor and EGFR resulted in synergistic expression of COX‐2 mRNA and protein involving transcriptional and post‐transcriptional mechanisms. Ang II and EGF induced transient phosphorylation of ERK, p38MAPK and CREB. Co‐stimulation with Ang II and EGF prolonged phosphorylation of ERK, p38MAPK, and CREB. The p38MAPK selective inhibitor, SB202190, but not the MEK selective inhibitor, PD98059, or the EGFR kinase inhibitor, AG1478, inhibited Ang II‐dependent COX‐2 expression and CREB phosphorylation. EGF‐dependent COX‐2 expression and CREB phosphorylation were inhibited by SB202190, PD98059, and AG1478. Inhibition of CREB expression using two separate RNAi methods blocked COX‐2 expression by Ang II and EGF. Expression of a dominant negative CREB mutant inhibited Ang II‐ and EGF‐dependent induction of the COX‐2 promoter. Ang II induced luciferase expression in cells transfected with the CRE‐luc reporter vector and cells co‐transfected with Gal4‐luc reporter vector and a Gal4‐CREB expression vector. Chromatin immunoprecipitation assays demonstrated CREB binding to the proximal rat COX‐2 promoter region containing a CRE cis‐acting element. These results indicate that co‐stimulation with Ang II and EGF synergistically induced COX‐2 expression in these intestinal epithelial cells through p38MAPK mediated signaling cascades that converge onto CREB. J. Cell. Physiol. 214:96–109, 2008. © 2007 Wiley‐Liss, Inc.
Claudin‐16 is directly phosphorylated by protein kinase a independently of a vasodilator‐stimulated phosphoprotein‐mediated pathway
Authors: Ikari Akira , Ito Midori , Okude Chiaki , Sawada Hayato , Harada Hitoshi , Degawa Masakuni , Sakai Hideki , Takahashi Tadanobu , Sugatani Junko , Miwa Masao 
Published: June 2007

AbstractClaudin‐16 (CLDN‐16) is involved in the paracellular reabsorption of Mg2+ in the thick ascending limb of Henle. The tight junctional localization and Mg2+ transport of CLDN‐16 are regulated by cAMP/PKA‐dependent phosphorylation. Here, we examined whether PKA phosphorylates CLDN‐16 in a direct or indirect manner. CLDN‐16 was stably expressed in Madin‐Darby canine kidney (MDCK) cells using a Tet‐OFF system. The phosphorylation of CLDN‐16 is upregulated by fetal calf serum (FCS). This phosphorylation was completely inhibited by a PKA inhibitor, N‐[2‐(p‐bromocinnamylamino)ethyl]‐5‐isoquinolinesulfonamide dihydrochloride. Without FCS, dibutyryl cAMP (DBcAMP) increased the phosphoserine level of CLDN‐16 in a concentration‐dependent manner. The phosphorylated CLDN‐16 elicited increases of transepithelial electrical resistance (TER) and transepithelial transport of Mg2+. Vasodilator‐stimulated phosphoprotein (VASP) was also phosphorylated in the presence of FCS or DBcAMP. In the glutathione‐S‐transferase (GST) pull down assay, a cytosolic carboxyl domain of CLDN‐16 was associated with PKA, but not with VASP. Furthermore, PKA was immunoprecipitated with CLDN‐16 in MDCK cells, but VASP was not. In cells expressing a dephosphorylated mutant (Ser160Ala) of VASP, CLDN‐16 was phosphorylated by DBcAMP and was associated with ZO‐1, a tight junctional‐scaffolding protein, without integral cell–cell junctions. We suggest that PKA directly phosphorylates CLDN‐16, resulting in the localization to tight junctions (TJs) and the maintenance of Mg2+ reabsorption. J. Cell. Physiol. 214:221–229, 2008. © 2007 Wiley‐Liss, Inc.
Representations of graphs and orthogonal latin square graphs
Authors: Erdös Paul , Evans Anthony B. 
Published: June 2007

AbstractWe define graph representations modulo integers and prove that any finite graph has a representation modulo some integer. We use this to obtain a new, simpler proof of Lindner, E. Mendelsohn, N. Mendelsohn, and Wolk's result that any finite graph can be represented as an orthogonal latin square graph.
Binding number and minimum degree for k‐factors
Authors: Tokushige Norihide 
Published: June 2007

AbstractIn this paper, we study mixed conditions on the binding number and the minimum degree of a graph G that guarantee the existence of a k‐factor in G. Among others, we prove that a graph G of order n with δ(G) ⩾ cn and bind(G) > (2 − 3c)/(1 − c), where c is any fixed number, has a 2‐factor.
Bounds for the vertex linear arboricity
Authors: Matsumoto Makoto 
Published: June 2007

AbstractThe vertex linear arboricity vla(G) of a nonempty graph G is the minimum number of subsets into which the vertex set V(G) can be partitioned so that each subset induces a subgraph whose connected components are paths. This paper provides an upper bound for vla(G) of a connected nonempty graph G, namely vla(G) ≦ 1 + ⌊δ(G)/2⌋ where δ(G) denotes the maximum degree of G. Moreover, if δ(G) is even, then vla(G) = 1 + ⌊δ(G)/2⌋ if and only if G is either a cycle or a complete graph.
Hamiltonian circuits in N2‐locally connected K1,3‐free graphs
Authors: Ryjáček ZdeněK 
Published: June 2007

AbstractThere are many results concerned with the hamiltonicity of K1,3‐free graphs. In the paper we show that one of the sufficient conditions for the K1,3‐free graph to be Hamiltonian can be improved using the concept of second‐type vertex neighborhood. The paper is concluded with a conjecture.
A note on Ki‐perfect graphs
Authors: Brown Jason I. , Corneil Derek G. , Mahjoub A. Ridha 
Published: June 2007

AbstractKi‐perfect graphs are a special instance of F ‐ G perfect graphs, where F and G are fixed graphs with F a partial subgraph of G. Given S, a collection of G‐subgraphs of graph K, an F ‐ G cover of S is a set of T of F‐subgraphs of K such that each subgraph in S contains as a subgraph a member of T. An F ‐ G packing of S is a subcollection S′⊆ S such that no two subgraphs in S′ have an F‐subgraph in common. K is F ‐ G perfect if for all such S, the minimum cardinality of an F ‐ G cover of S equals the maximum cardinality of an F ‐ G packing of S. Thus Ki‐perfect graphs are precisely Ki‐1 ‐ Ki perfect graphs. We develop a hypergraph characterization of F ‐ G perfect graphs that leads to an alternate proof of previous results on Ki‐perfect graphs as well as to a characterization of F ‐ G perfect graphs for other instances of F and G.
Path‐isomorphic networks
Authors: Hartvigsen David 
Published: June 2007

AbstractTwo source‐sink (directed) networks are called path‐isomorphic if there exists a bijection π between their arc sets that preserves (simple) source‐sink directed paths. Although path‐isomorphic networks need not be isomorphic (they need not even have the same number of nodes), we show that several properties are preserved. For example, suppose N and N′ are path‐isomorphic. Then, N is acyclic if and only if N′ is acyclic. B is the arc set of block of N if and only if π(B) is the arc set of a block of N′. Also, D is the arc set of a dicomponent of N if and only if π(D) is the arc set of a dicomponent of N′. In addition, we prove a dipath version of Whitney's well‐known 2‐isomorphism theorem for a special class of networks, which includes the acyclic networks.
On the decomposition of Kn into complete m‐partite graphs
Authors: Huang Qingxue 
Published: June 2007

AbstractGraham and Pollak [3] proved that n −1 is the minimum number of edge‐disjoint complete bipartite subgraphs into which the edges of Kn can be decomposed. Using a linear algebraic technique, Tverberg [2] gives a different proof of that result. We apply his technique to show that for “almost all n,” ⌊ (n + m −3)/(m −1) ⌋ is the minimum number of edge‐disjoint complete m‐partite subgraphs in a decomposition of Kn.
An upper bound on the ramsey number R(K3, G) depending only on the size of the graph G
Authors: Sidorenko A. F. 
Published: June 2007

AbstractHarary stated the conjecture that for any graph G with n edges and without isolated vertices r(K3,G) ⩽ 2n + 1. Erdös, Faudree, Rousseau, and Schelp proved that r(K3,G) ⩽ ⌈8/3n⌉. Here we prove that r(K3,G) ⩽ ⌊5/2n⌋ −1 for n > 3.
Long dominating cycles and paths in graphs with large neighborhood unions
Authors: Broersma H. J. , Veldman H. J. 
Published: June 2007

AbstractLet G be a graph of order n and define NC(G) = min{|N(u) ∪ N(v)| |uv ∉ E(G)}. A cycle C of G is called a dominating cycle or D‐cycle if V(G) ‐ V(C) is an independent set. A D‐path is defined analogously. The following result is proved: if G is 2‐connected and contains a D‐cycle, then G contains a D‐cycle of length at least min{n, 2NC(G)} unless G is the Petersen graph. By combining this result with a known sufficient condition for the existence of a D‐cycle, a common generalization of Ore's Theorem and several recent “neighborhood union results” is obtained. An analogous result on long D‐paths is also established.
On a conjecture of wang and williams
Authors: Mahadev N. V. R. , Peled Uri N. 
Published: June 2007

AbstractWang and Williams defined a threshold assignment for a graph G as an assignment of a non‐negative weight to each vertex and edge of G, and a threshold t, such that a set S of vertices is stable if and only if the total weight of the subgraph induced by S does not exceed t ‐ 1. This is always possible with zero vertex‐weights, unit edge‐weights, and t = 1. By definition, a threshold graph is a graph having a threshold assignment with zero edge‐weights. The threshold weight of G is the minimum total edgeweight of a threshold assignment of G. A graph G = (V,E) is called heavy if its threshold weight is |E|. A clique C of G is called big if |E(C)| > |E(G ‐ C)|. Wang and Williams showed that graphs with a big clique are not heavy, and conjectured the converse. They verified the conjecture for triangle‐free graphs. We disprove the conjecture in general, but prove it for perfect graphs.
How to deal with unlabeled random graphs
Authors: Łuczak Tomasz 
Published: June 2007

AbstractLet U(n,M) be a graph chosen at random from the family of all unlabeled graphs with n vertices and M edges. In the paper we study the asymptotic behavior of U(n,M) when n → ∞. In particular, we show how properties of U(n,M) could be derived from analogous properties of a labeled random graph.
Smallest regular graphs with prescribed odd girth
Authors: Zhang Guo‐Hui 
Published: June 2007

AbstractThe odd girth of a graph G gives the length of a shortest odd cycle in G. Let f(k,g) denote the smallest n such that there exists a k‐regular graph of order n and odd girth g. The exact values of f(k,g) are determined if one of the following holds:
k > 2g −5 and k is a prime number,
k > (2⌊(g + 1)/4⌋ −1)2, and
k is a perfect square.
Almost resolvable Pk‐decompositions of complete graphs
Authors: Yu Min‐Li 
Published: June 2007

AbstractAn almost Pk‐factor of G is a Pk‐factor of G ‐ {v} for some vertex v. An almost resolvable Pk‐decomposition of λKn is a partition of the edges of λKn into almost Pk‐factors. We prove that necessary and sufficient conditions for the existence of an almost resolvable Pk‐decomposition of λKn are n ≡ 1 (mod k) and λnk/2 ≡ 0 (mod k −1).
Vertex‐transitive graphs and vertex‐transitive maps
Authors: Babai László 
Published: June 2007

AbstractWe consider vertex‐transitive graphs embeddable on a fixed surface. We prove that all but a finite number of them admit embeddings as vertex‐transitive maps on surfaces of nonnegative Euler characteristic (sphere, projective plane, torus, or Klein bottle). It follows that with the exception of the cycles and a finite number of additional graphs, they are factor graphs of semiregular plane tilings. The results generalize previous work on the genus of minimal Cayley graphs by V. Proulx and T. W. Tucker and were obtained independently by C. Thomassen, with significant differences in the methods used. Our method is based on an excursion into the infinite. The local structure of our finite graphs is studied via a pointwise limit construction, and the infinite vertex‐transitive graphs obtained as such limits are classified by their connectivity and the number of ends. In two appendices, we derive a combinatorial version of Hurwitz's Theorem, and classify the vertex‐transitive maps on the Klein bottle.
Cycles intersecting a prescribed vertex set
Authors: Kaneko Atsushi , Saito Akira 
Published: June 2007

AbstractA graph is said to have property P(k,l)(k ⩾ l) if for any X ∈ (Gk) there exists a cycle such that |X ∩ V(C)| = l. Obviously an n‐connected graph (n ⩾ 2) satisfies P(n,n). In this paper, we study parameters k and l such that every n‐connected graph satisfies P(k,l). We show that for r = 1 or 2 every n‐connected graph satisfies P(n + r,n). For r = 3, there are infinitely many 3‐connected graphs that do not satisfy P(6,3). However, if n ⩾ max{3,(2r −1)(r + 1)}, then every n‐connected graph satisfies P(n + r,n).
The maximum valency of regular graphs with given order and odd girth
Authors: Zhang Guo‐Hui 
Published: June 2007

AbstractThe odd girth of a graph G is the length of a shortest odd cycle in G. Let d(n, g) denote the largest k such that there exists a k‐regular graph of order n and odd girth g. It is shown that dn, g ≥ 2|n/g≥ if n ≥ 2g. As a consequence, we prove a conjecture of Pullman and Wormald, which says that there exists a 2j‐regular graph of order n and odd girth g if and only if n ≥ gj, where g ≥ 5 is odd and j ≥ 2. A different variation of the problem is also discussed.
The connectivity of the basis graph of a branching greedoid
Authors: Broersma H. J. , Xueliang Li 
Published: June 2007

AbstractA result of Korte and Lovász states that the basis graph of every 2‐ connected greedoid is connected. We prove that the basis graph of every 3‐connected branching greedoid is (δ ‐‐ 1)‐connected, where δ is the minimum in‐degree (disregarding the root) of the underlying rooted directed (multi) graph. We also give examples showing that this results is (in some sense) best possible.
2‐neighborhoods and hamiltonian conditions
Authors: Ronghua Shi 
Published: June 2007

AbstractIn terms of local properties of 2‐neighborhoods (sets of vertices at distance 2 from a vertex or a subgraph), new sufficient conditions for a graph to be hamiltonian are obtained. In particular, results of Fan and Chavátal and Erdös are generalized. The new results also apply to graphs with larger diameter.
Subgraphs of a hypercube containing no small even cycles
Authors: Chung Fan R. K. 
Published: June 2007

AbstractWe investigate several Ramsey‐Turán type problems for subgraphs of a hypercube. We obtain upper and lower bounds for the maximum number of edges in a subgraph of a hypercube containing no four‐cycles or more generally, no 2k‐cycles C2k. These extermal results imply, for example, the following Ramsey theorems for hypercubes: A hypercube can always be edge‐partitioned into four subgraphs, each of which contains no six‐cycle. However, for any integer t, if the n‐cube is edge‐partitioned into t sub‐graphs, then one of the subgraphs must contain an edight‐cycle, provided only than n is sufficiently large (depending only on t).
s‐strongly perfect cartesian product of graphs
Authors: Olaru Elefterie , Mǎndrescu Eugen 
Published: June 2007

AbstractThe study of perfectness, via the strong perfect graph conjecture, has given rise to numerous investigations concerning the structure of many particular classes of perfect graphs. In “Perfect Product Graphs” (Discrete Mathematics, Vol. 20, 1977, pp. 177‐‐186), G. Ravindra and K. R. Parthasarathy tried, but unfortunately without success, to characterize the perfectness of the cartesian product of graphs (see also MR No. 58‐‐10567, 1979). In this paper we completely characterize the graphs that are both nontrivial cartesian products and s‐strongly perfect.
Centroids and medians of finite metric spaces
Authors: Bandelt Hans‐ JÜRgen 
Published: June 2007

AbstractThe median of a weighted finite metric space consists of the points minimizing the total weighted distance to the points of the space. The centroid is formed by the points p satisfying the following minimax condition: the maximal weight of a geodesically convex set not containing a point X attains its minimum at p. It is well known that in a tree network the centroid and the median coincide for every distribution of weights. The metric spaces for which the latter property is characteristic are determined in this paper. These spaces are obtained from three classess of graphs: median graphs, joins of complete graphs with edgeless graphs, and joins of two‐vertex edgeless graphs.
On the irregularity strength of the m × n grid
Authors: Dinitz Jeffrey H. , Garnick David K. , Gyárfás Andras 
Published: June 2007

AbstractGiven a graph G with weighting w: E(G) ← Z+, the Strength of G(w) is the maximum weight on any edge. The sum of a vertex in G(w) is the sum of the weights of all its incident edges. The network G(w) is irregular if the vertex sums are distinct. The irregularity strength of G is the minimum strength of the graph under all irregular weightings. In this paper we determine the irregularity strength of the m × n grid for certain m and n. In particular, for every positive integer d we find the irregularity strength for all but a finite number of m × n grids where n ‐ m = d. In addition, we present a general lower bound for the irregularity strength of graphs. © 1992 John Wiley & Sons, Inc.
Induced matchings in cubic graphs
Authors: Horák Peter , Qing He , Trotter William T. 
Published: June 2007

AbstractIn this paper, we show that the edge set of a cubic graph can always be partitioned into 10 subsets, each of which induces a matching in the graph. This result is a special case of a general conjecture made by Erdös and Nešetřil: For each d ≥ 3, the edge set of a graph of maximum degree d can always be partitioned into [5d2/4] subsets each of which induces a matching. © 1993 John Wiley & Sons, Inc.
First cosmogenic 10Be age constraint on the timing of Younger Dryas glaciation and ice cap thickness, western Scottish Highlands
Authors: Golledge Nicholas R. , Fabel Derek , Everest Jeremy D. , Freeman Stewart , Binnie Steven 
Published: June 2007

AbstractWe use cosmogenic 10Be surface exposure age techniques at a locality close to Rannoch Moor, western Scottish Highlands, in order to establish the age and chronology of its most recent glaciation. Glacial erratics and an in situ bedrock quartz vein sampled from this site—the summit of Beinn Inverveigh—have yielded zero‐erosion exposure ages of 12.9 ± 1.5 ka to 11.6 ± 1.0 ka, implying complete ice cover of the mountain during the Younger Dryas, or Loch Lomond Stadial. These results fit closely with published 14C dates that bracket the maximum (lateral) extent of ice cap outlet glaciers, and are the first internally consistent ages to specifically address this period of glaciation in Scotland. Furthermore, the dates imply that previous palaeoglaciological reconstructions for this area may have underestimated both the thickness of the former ice cap and, by implication, its volume. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.
Determination of apparent amylose content, pasting properties and gel texture of rice starch by near‐infrared spectroscopy
Authors: Bao Jinsong , Wang Yuefei , Shen Yun 
Published: June 2007

AbstractFor breeding rice with improved quality, apparent amylose content (AAC), rapid visco analyser (RVA) pasting viscosities and gel texture properties may be routinely measured. As a direct measurement is time‐consuming and expensive, rapid predictive method based on near‐infrared spectroscopy (NIRS) is useful for measurement of these quality parameters. In this study, calibration models were developed using modified partial least‐squares regression with different mathematical treatments based on the grain and flour spectra of non‐waxy rice alone or in combination with waxy rice. The results showed that calibration models built with flour spectra are more robust than those with grain spectra, and with total rice including waxy rice are superior to those with only non‐waxy rice. Some starch quality parameters, such as AAC, setback viscosity (SB), pasting temperature (PT), hardness (HD) and cohesiveness (COH) could be predicted with sufficient accuracy by NIRS based on flour spectra, whereas only AAC and PT could be predicted with sufficient accuracy based on grain spectra. All the models reported here are usable for rough sample screening (cold paste viscosity and breakdown viscosity), sample screening (SB, PT and COH) and for most applications (AAC and HD) for routine screening of a large number of samples in the early generation selection in breeding programs. However, for accurate assay of the pasting viscosity and gel textural parameters, direct instrumental measurement should be employed in later generations. Copyright © 2007 Society of Chemical Industry
The fate of the five‐cent fare VII. Toronto sticks to 3.9 cents
Authors: Maitland George H. 
Published: June 2007

AbstractIn Toronto, Canada, the replacing of a five‐cent fare by something higher has never been discussed, for the very good reason that there is no five‐cent fare to replace. The average fare on the lines of the Toronto Railway Company is less than four cents, and under an agreement dating back to 1891 this fare cannot be increased.
The fate of the five‐cent fare. X. Minneapolis keeps home rule and the five‐cent rate
Authors: Anderson William 
Published: June 2007

AbstractThe necessary basis for fair dealing between the street railroads and the people is scientific valuation, but as no one knows what that is and the United States Bureau of Standards still refrains from the task of setting up standards in this field, Minneapolis, for instence, gets figures that are $10,000,000 apart!